]> Pileus Git - ~andy/linux/blobdiff - drivers/block/drbd/drbd_main.c
Merge branch 'drbd-8.4_ed6' into for-3.8-drivers-drbd-8.4_ed6
[~andy/linux] / drivers / block / drbd / drbd_main.c
index 9b833e0fb4409d4dd03ad25bbb7495aae7a928d0..52de26daa1f6c4dceed2115dac702aa431d2d289 100644 (file)
 
 #include "drbd_vli.h"
 
-struct after_state_chg_work {
-       struct drbd_work w;
-       union drbd_state os;
-       union drbd_state ns;
-       enum chg_state_flags flags;
-       struct completion *done;
-};
-
 static DEFINE_MUTEX(drbd_main_mutex);
 int drbdd_init(struct drbd_thread *);
 int drbd_worker(struct drbd_thread *);
@@ -72,21 +64,17 @@ int drbd_asender(struct drbd_thread *);
 int drbd_init(void);
 static int drbd_open(struct block_device *bdev, fmode_t mode);
 static int drbd_release(struct gendisk *gd, fmode_t mode);
-static int w_after_state_ch(struct drbd_conf *mdev, struct drbd_work *w, int unused);
-static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
-                          union drbd_state ns, enum chg_state_flags flags);
-static int w_md_sync(struct drbd_conf *mdev, struct drbd_work *w, int unused);
+static int w_md_sync(struct drbd_work *w, int unused);
 static void md_sync_timer_fn(unsigned long data);
-static int w_bitmap_io(struct drbd_conf *mdev, struct drbd_work *w, int unused);
-static int w_go_diskless(struct drbd_conf *mdev, struct drbd_work *w, int unused);
-static void _tl_clear(struct drbd_conf *mdev);
+static int w_bitmap_io(struct drbd_work *w, int unused);
+static int w_go_diskless(struct drbd_work *w, int unused);
 
 MODULE_AUTHOR("Philipp Reisner <phil@linbit.com>, "
              "Lars Ellenberg <lars@linbit.com>");
 MODULE_DESCRIPTION("drbd - Distributed Replicated Block Device v" REL_VERSION);
 MODULE_VERSION(REL_VERSION);
 MODULE_LICENSE("GPL");
-MODULE_PARM_DESC(minor_count, "Maximum number of drbd devices ("
+MODULE_PARM_DESC(minor_count, "Approximate number of drbd devices ("
                 __stringify(DRBD_MINOR_COUNT_MIN) "-" __stringify(DRBD_MINOR_COUNT_MAX) ")");
 MODULE_ALIAS_BLOCKDEV_MAJOR(DRBD_MAJOR);
 
@@ -98,7 +86,6 @@ MODULE_PARM_DESC(allow_oos, "DONT USE!");
 module_param(minor_count, uint, 0444);
 module_param(disable_sendpage, bool, 0644);
 module_param(allow_oos, bool, 0);
-module_param(cn_idx, uint, 0444);
 module_param(proc_details, int, 0644);
 
 #ifdef CONFIG_DRBD_FAULT_INJECTION
@@ -120,7 +107,6 @@ module_param(fault_devs, int, 0644);
 unsigned int minor_count = DRBD_MINOR_COUNT_DEF;
 bool disable_sendpage;
 bool allow_oos;
-unsigned int cn_idx = CN_IDX_DRBD;
 int proc_details;       /* Detail level in proc drbd*/
 
 /* Module parameter for setting the user mode helper program
@@ -132,10 +118,11 @@ module_param_string(usermode_helper, usermode_helper, sizeof(usermode_helper), 0
 /* in 2.6.x, our device mapping and config info contains our virtual gendisks
  * as member "struct gendisk *vdisk;"
  */
-struct drbd_conf **minor_table;
+struct idr minors;
+struct list_head drbd_tconns;  /* list of struct drbd_tconn */
 
 struct kmem_cache *drbd_request_cache;
-struct kmem_cache *drbd_ee_cache;      /* epoch entries */
+struct kmem_cache *drbd_ee_cache;      /* peer requests */
 struct kmem_cache *drbd_bm_ext_cache;  /* bitmap extents */
 struct kmem_cache *drbd_al_ext_cache;  /* activity log extents */
 mempool_t *drbd_request_mempool;
@@ -160,1715 +147,293 @@ static const struct block_device_operations drbd_ops = {
        .owner =   THIS_MODULE,
        .open =    drbd_open,
        .release = drbd_release,
-};
-
-struct bio *bio_alloc_drbd(gfp_t gfp_mask)
-{
-       if (!drbd_md_io_bio_set)
-               return bio_alloc(gfp_mask, 1);
-
-       return bio_alloc_bioset(gfp_mask, 1, drbd_md_io_bio_set);
-}
-
-#ifdef __CHECKER__
-/* When checking with sparse, and this is an inline function, sparse will
-   give tons of false positives. When this is a real functions sparse works.
- */
-int _get_ldev_if_state(struct drbd_conf *mdev, enum drbd_disk_state mins)
-{
-       int io_allowed;
-
-       atomic_inc(&mdev->local_cnt);
-       io_allowed = (mdev->state.disk >= mins);
-       if (!io_allowed) {
-               if (atomic_dec_and_test(&mdev->local_cnt))
-                       wake_up(&mdev->misc_wait);
-       }
-       return io_allowed;
-}
-
-#endif
-
-/**
- * DOC: The transfer log
- *
- * The transfer log is a single linked list of &struct drbd_tl_epoch objects.
- * mdev->newest_tle points to the head, mdev->oldest_tle points to the tail
- * of the list. There is always at least one &struct drbd_tl_epoch object.
- *
- * Each &struct drbd_tl_epoch has a circular double linked list of requests
- * attached.
- */
-static int tl_init(struct drbd_conf *mdev)
-{
-       struct drbd_tl_epoch *b;
-
-       /* during device minor initialization, we may well use GFP_KERNEL */
-       b = kmalloc(sizeof(struct drbd_tl_epoch), GFP_KERNEL);
-       if (!b)
-               return 0;
-       INIT_LIST_HEAD(&b->requests);
-       INIT_LIST_HEAD(&b->w.list);
-       b->next = NULL;
-       b->br_number = 4711;
-       b->n_writes = 0;
-       b->w.cb = NULL; /* if this is != NULL, we need to dec_ap_pending in tl_clear */
-
-       mdev->oldest_tle = b;
-       mdev->newest_tle = b;
-       INIT_LIST_HEAD(&mdev->out_of_sequence_requests);
-       INIT_LIST_HEAD(&mdev->barrier_acked_requests);
-
-       mdev->tl_hash = NULL;
-       mdev->tl_hash_s = 0;
-
-       return 1;
-}
-
-static void tl_cleanup(struct drbd_conf *mdev)
-{
-       D_ASSERT(mdev->oldest_tle == mdev->newest_tle);
-       D_ASSERT(list_empty(&mdev->out_of_sequence_requests));
-       kfree(mdev->oldest_tle);
-       mdev->oldest_tle = NULL;
-       kfree(mdev->unused_spare_tle);
-       mdev->unused_spare_tle = NULL;
-       kfree(mdev->tl_hash);
-       mdev->tl_hash = NULL;
-       mdev->tl_hash_s = 0;
-}
-
-/**
- * _tl_add_barrier() - Adds a barrier to the transfer log
- * @mdev:      DRBD device.
- * @new:       Barrier to be added before the current head of the TL.
- *
- * The caller must hold the req_lock.
- */
-void _tl_add_barrier(struct drbd_conf *mdev, struct drbd_tl_epoch *new)
-{
-       struct drbd_tl_epoch *newest_before;
-
-       INIT_LIST_HEAD(&new->requests);
-       INIT_LIST_HEAD(&new->w.list);
-       new->w.cb = NULL; /* if this is != NULL, we need to dec_ap_pending in tl_clear */
-       new->next = NULL;
-       new->n_writes = 0;
-
-       newest_before = mdev->newest_tle;
-       new->br_number = newest_before->br_number+1;
-       if (mdev->newest_tle != new) {
-               mdev->newest_tle->next = new;
-               mdev->newest_tle = new;
-       }
-}
-
-/**
- * tl_release() - Free or recycle the oldest &struct drbd_tl_epoch object of the TL
- * @mdev:      DRBD device.
- * @barrier_nr:        Expected identifier of the DRBD write barrier packet.
- * @set_size:  Expected number of requests before that barrier.
- *
- * In case the passed barrier_nr or set_size does not match the oldest
- * &struct drbd_tl_epoch objects this function will cause a termination
- * of the connection.
- */
-void tl_release(struct drbd_conf *mdev, unsigned int barrier_nr,
-                      unsigned int set_size)
-{
-       struct drbd_tl_epoch *b, *nob; /* next old barrier */
-       struct list_head *le, *tle;
-       struct drbd_request *r;
-
-       spin_lock_irq(&mdev->req_lock);
-
-       b = mdev->oldest_tle;
-
-       /* first some paranoia code */
-       if (b == NULL) {
-               dev_err(DEV, "BAD! BarrierAck #%u received, but no epoch in tl!?\n",
-                       barrier_nr);
-               goto bail;
-       }
-       if (b->br_number != barrier_nr) {
-               dev_err(DEV, "BAD! BarrierAck #%u received, expected #%u!\n",
-                       barrier_nr, b->br_number);
-               goto bail;
-       }
-       if (b->n_writes != set_size) {
-               dev_err(DEV, "BAD! BarrierAck #%u received with n_writes=%u, expected n_writes=%u!\n",
-                       barrier_nr, set_size, b->n_writes);
-               goto bail;
-       }
-
-       /* Clean up list of requests processed during current epoch */
-       list_for_each_safe(le, tle, &b->requests) {
-               r = list_entry(le, struct drbd_request, tl_requests);
-               _req_mod(r, barrier_acked);
-       }
-       /* There could be requests on the list waiting for completion
-          of the write to the local disk. To avoid corruptions of
-          slab's data structures we have to remove the lists head.
-
-          Also there could have been a barrier ack out of sequence, overtaking
-          the write acks - which would be a bug and violating write ordering.
-          To not deadlock in case we lose connection while such requests are
-          still pending, we need some way to find them for the
-          _req_mode(connection_lost_while_pending).
-
-          These have been list_move'd to the out_of_sequence_requests list in
-          _req_mod(, barrier_acked) above.
-          */
-       list_splice_init(&b->requests, &mdev->barrier_acked_requests);
-
-       nob = b->next;
-       if (drbd_test_and_clear_flag(mdev, CREATE_BARRIER)) {
-               _tl_add_barrier(mdev, b);
-               if (nob)
-                       mdev->oldest_tle = nob;
-               /* if nob == NULL b was the only barrier, and becomes the new
-                  barrier. Therefore mdev->oldest_tle points already to b */
-       } else {
-               D_ASSERT(nob != NULL);
-               mdev->oldest_tle = nob;
-               kfree(b);
-       }
-
-       spin_unlock_irq(&mdev->req_lock);
-       dec_ap_pending(mdev);
-
-       return;
-
-bail:
-       spin_unlock_irq(&mdev->req_lock);
-       drbd_force_state(mdev, NS(conn, C_PROTOCOL_ERROR));
-}
-
-
-/**
- * _tl_restart() - Walks the transfer log, and applies an action to all requests
- * @mdev:      DRBD device.
- * @what:       The action/event to perform with all request objects
- *
- * @what might be one of connection_lost_while_pending, resend, fail_frozen_disk_io,
- * restart_frozen_disk_io.
- */
-static void _tl_restart(struct drbd_conf *mdev, enum drbd_req_event what)
-{
-       struct drbd_tl_epoch *b, *tmp, **pn;
-       struct list_head *le, *tle, carry_reads;
-       struct drbd_request *req;
-       int rv, n_writes, n_reads;
-
-       b = mdev->oldest_tle;
-       pn = &mdev->oldest_tle;
-       while (b) {
-               n_writes = 0;
-               n_reads = 0;
-               INIT_LIST_HEAD(&carry_reads);
-               list_for_each_safe(le, tle, &b->requests) {
-                       req = list_entry(le, struct drbd_request, tl_requests);
-                       rv = _req_mod(req, what);
-
-                       n_writes += (rv & MR_WRITE) >> MR_WRITE_SHIFT;
-                       n_reads  += (rv & MR_READ) >> MR_READ_SHIFT;
-               }
-               tmp = b->next;
-
-               if (n_writes) {
-                       if (what == resend) {
-                               b->n_writes = n_writes;
-                               if (b->w.cb == NULL) {
-                                       b->w.cb = w_send_barrier;
-                                       inc_ap_pending(mdev);
-                                       drbd_set_flag(mdev, CREATE_BARRIER);
-                               }
-
-                               drbd_queue_work(&mdev->data.work, &b->w);
-                       }
-                       pn = &b->next;
-               } else {
-                       if (n_reads)
-                               list_add(&carry_reads, &b->requests);
-                       /* there could still be requests on that ring list,
-                        * in case local io is still pending */
-                       list_del(&b->requests);
-
-                       /* dec_ap_pending corresponding to queue_barrier.
-                        * the newest barrier may not have been queued yet,
-                        * in which case w.cb is still NULL. */
-                       if (b->w.cb != NULL)
-                               dec_ap_pending(mdev);
-
-                       if (b == mdev->newest_tle) {
-                               /* recycle, but reinit! */
-                               D_ASSERT(tmp == NULL);
-                               INIT_LIST_HEAD(&b->requests);
-                               list_splice(&carry_reads, &b->requests);
-                               INIT_LIST_HEAD(&b->w.list);
-                               b->w.cb = NULL;
-                               b->br_number = net_random();
-                               b->n_writes = 0;
-
-                               *pn = b;
-                               break;
-                       }
-                       *pn = tmp;
-                       kfree(b);
-               }
-               b = tmp;
-               list_splice(&carry_reads, &b->requests);
-       }
-
-       /* Actions operating on the disk state, also want to work on
-          requests that got barrier acked. */
-
-       list_for_each_safe(le, tle, &mdev->barrier_acked_requests) {
-               req = list_entry(le, struct drbd_request, tl_requests);
-               _req_mod(req, what);
-       }
-}
-
-
-/**
- * tl_clear() - Clears all requests and &struct drbd_tl_epoch objects out of the TL
- * @mdev:      DRBD device.
- *
- * This is called after the connection to the peer was lost. The storage covered
- * by the requests on the transfer gets marked as our of sync. Called from the
- * receiver thread and the worker thread.
- */
-void tl_clear(struct drbd_conf *mdev)
-{
-       spin_lock_irq(&mdev->req_lock);
-       _tl_clear(mdev);
-       spin_unlock_irq(&mdev->req_lock);
-}
-
-static void _tl_clear(struct drbd_conf *mdev)
-{
-       struct list_head *le, *tle;
-       struct drbd_request *r;
-
-       _tl_restart(mdev, connection_lost_while_pending);
-
-       /* we expect this list to be empty. */
-       D_ASSERT(list_empty(&mdev->out_of_sequence_requests));
-
-       /* but just in case, clean it up anyways! */
-       list_for_each_safe(le, tle, &mdev->out_of_sequence_requests) {
-               r = list_entry(le, struct drbd_request, tl_requests);
-               /* It would be nice to complete outside of spinlock.
-                * But this is easier for now. */
-               _req_mod(r, connection_lost_while_pending);
-       }
-
-       /* ensure bit indicating barrier is required is clear */
-       drbd_clear_flag(mdev, CREATE_BARRIER);
-
-       memset(mdev->app_reads_hash, 0, APP_R_HSIZE*sizeof(void *));
-
-}
-
-void tl_restart(struct drbd_conf *mdev, enum drbd_req_event what)
-{
-       spin_lock_irq(&mdev->req_lock);
-       _tl_restart(mdev, what);
-       spin_unlock_irq(&mdev->req_lock);
-}
-
-/**
- * tl_abort_disk_io() - Abort disk I/O for all requests for a certain mdev in the TL
- * @mdev:      DRBD device.
- */
-void tl_abort_disk_io(struct drbd_conf *mdev)
-{
-       struct drbd_tl_epoch *b;
-       struct list_head *le, *tle;
-       struct drbd_request *req;
-
-       spin_lock_irq(&mdev->req_lock);
-       b = mdev->oldest_tle;
-       while (b) {
-               list_for_each_safe(le, tle, &b->requests) {
-                       req = list_entry(le, struct drbd_request, tl_requests);
-                       if (!(req->rq_state & RQ_LOCAL_PENDING))
-                               continue;
-                       _req_mod(req, abort_disk_io);
-               }
-               b = b->next;
-       }
-
-       list_for_each_safe(le, tle, &mdev->barrier_acked_requests) {
-               req = list_entry(le, struct drbd_request, tl_requests);
-               if (!(req->rq_state & RQ_LOCAL_PENDING))
-                       continue;
-               _req_mod(req, abort_disk_io);
-       }
-
-       spin_unlock_irq(&mdev->req_lock);
-}
-
-/**
- * cl_wide_st_chg() - true if the state change is a cluster wide one
- * @mdev:      DRBD device.
- * @os:                old (current) state.
- * @ns:                new (wanted) state.
- */
-static int cl_wide_st_chg(struct drbd_conf *mdev,
-                         union drbd_state os, union drbd_state ns)
-{
-       return (os.conn >= C_CONNECTED && ns.conn >= C_CONNECTED &&
-                ((os.role != R_PRIMARY && ns.role == R_PRIMARY) ||
-                 (os.conn != C_STARTING_SYNC_T && ns.conn == C_STARTING_SYNC_T) ||
-                 (os.conn != C_STARTING_SYNC_S && ns.conn == C_STARTING_SYNC_S) ||
-                 (os.disk != D_FAILED && ns.disk == D_FAILED))) ||
-               (os.conn >= C_CONNECTED && ns.conn == C_DISCONNECTING) ||
-               (os.conn == C_CONNECTED && ns.conn == C_VERIFY_S);
-}
-
-enum drbd_state_rv
-drbd_change_state(struct drbd_conf *mdev, enum chg_state_flags f,
-                 union drbd_state mask, union drbd_state val)
-{
-       unsigned long flags;
-       union drbd_state os, ns;
-       enum drbd_state_rv rv;
-
-       spin_lock_irqsave(&mdev->req_lock, flags);
-       os = mdev->state;
-       ns.i = (os.i & ~mask.i) | val.i;
-       rv = _drbd_set_state(mdev, ns, f, NULL);
-       ns = mdev->state;
-       spin_unlock_irqrestore(&mdev->req_lock, flags);
-
-       return rv;
-}
-
-/**
- * drbd_force_state() - Impose a change which happens outside our control on our state
- * @mdev:      DRBD device.
- * @mask:      mask of state bits to change.
- * @val:       value of new state bits.
- */
-void drbd_force_state(struct drbd_conf *mdev,
-       union drbd_state mask, union drbd_state val)
-{
-       drbd_change_state(mdev, CS_HARD, mask, val);
-}
-
-static enum drbd_state_rv is_valid_state(struct drbd_conf *, union drbd_state);
-static enum drbd_state_rv is_valid_state_transition(struct drbd_conf *,
-                                                   union drbd_state,
-                                                   union drbd_state);
-enum sanitize_state_warnings {
-       NO_WARNING,
-       ABORTED_ONLINE_VERIFY,
-       ABORTED_RESYNC,
-       CONNECTION_LOST_NEGOTIATING,
-       IMPLICITLY_UPGRADED_DISK,
-       IMPLICITLY_UPGRADED_PDSK,
-};
-static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state os,
-                                      union drbd_state ns, enum sanitize_state_warnings *warn);
-int drbd_send_state_req(struct drbd_conf *,
-                       union drbd_state, union drbd_state);
-
-static enum drbd_state_rv
-_req_st_cond(struct drbd_conf *mdev, union drbd_state mask,
-            union drbd_state val)
-{
-       union drbd_state os, ns;
-       unsigned long flags;
-       enum drbd_state_rv rv;
-
-       if (drbd_test_and_clear_flag(mdev, CL_ST_CHG_SUCCESS))
-               return SS_CW_SUCCESS;
-
-       if (drbd_test_and_clear_flag(mdev, CL_ST_CHG_FAIL))
-               return SS_CW_FAILED_BY_PEER;
-
-       rv = 0;
-       spin_lock_irqsave(&mdev->req_lock, flags);
-       os = mdev->state;
-       ns.i = (os.i & ~mask.i) | val.i;
-       ns = sanitize_state(mdev, os, ns, NULL);
-
-       if (!cl_wide_st_chg(mdev, os, ns))
-               rv = SS_CW_NO_NEED;
-       if (!rv) {
-               rv = is_valid_state(mdev, ns);
-               if (rv == SS_SUCCESS) {
-                       rv = is_valid_state_transition(mdev, ns, os);
-                       if (rv == SS_SUCCESS)
-                               rv = SS_UNKNOWN_ERROR; /* cont waiting, otherwise fail. */
-               }
-       }
-       spin_unlock_irqrestore(&mdev->req_lock, flags);
-
-       return rv;
-}
-
-/**
- * drbd_req_state() - Perform an eventually cluster wide state change
- * @mdev:      DRBD device.
- * @mask:      mask of state bits to change.
- * @val:       value of new state bits.
- * @f:         flags
- *
- * Should not be called directly, use drbd_request_state() or
- * _drbd_request_state().
- */
-static enum drbd_state_rv
-drbd_req_state(struct drbd_conf *mdev, union drbd_state mask,
-              union drbd_state val, enum chg_state_flags f)
-{
-       struct completion done;
-       unsigned long flags;
-       union drbd_state os, ns;
-       enum drbd_state_rv rv;
-
-       init_completion(&done);
-
-       if (f & CS_SERIALIZE)
-               mutex_lock(&mdev->state_mutex);
-
-       spin_lock_irqsave(&mdev->req_lock, flags);
-       os = mdev->state;
-       ns.i = (os.i & ~mask.i) | val.i;
-       ns = sanitize_state(mdev, os, ns, NULL);
-
-       if (cl_wide_st_chg(mdev, os, ns)) {
-               rv = is_valid_state(mdev, ns);
-               if (rv == SS_SUCCESS)
-                       rv = is_valid_state_transition(mdev, ns, os);
-               spin_unlock_irqrestore(&mdev->req_lock, flags);
-
-               if (rv < SS_SUCCESS) {
-                       if (f & CS_VERBOSE)
-                               print_st_err(mdev, os, ns, rv);
-                       goto abort;
-               }
-
-               drbd_state_lock(mdev);
-               if (!drbd_send_state_req(mdev, mask, val)) {
-                       drbd_state_unlock(mdev);
-                       rv = SS_CW_FAILED_BY_PEER;
-                       if (f & CS_VERBOSE)
-                               print_st_err(mdev, os, ns, rv);
-                       goto abort;
-               }
-
-               if (mask.conn == C_MASK && val.conn == C_DISCONNECTING)
-                       drbd_set_flag(mdev, DISCONNECT_SENT);
-
-               wait_event(mdev->state_wait,
-                       (rv = _req_st_cond(mdev, mask, val)));
-
-               if (rv < SS_SUCCESS) {
-                       drbd_state_unlock(mdev);
-                       if (f & CS_VERBOSE)
-                               print_st_err(mdev, os, ns, rv);
-                       goto abort;
-               }
-               spin_lock_irqsave(&mdev->req_lock, flags);
-               os = mdev->state;
-               ns.i = (os.i & ~mask.i) | val.i;
-               rv = _drbd_set_state(mdev, ns, f, &done);
-               drbd_state_unlock(mdev);
-       } else {
-               rv = _drbd_set_state(mdev, ns, f, &done);
-       }
-
-       spin_unlock_irqrestore(&mdev->req_lock, flags);
-
-       if (f & CS_WAIT_COMPLETE && rv == SS_SUCCESS) {
-               D_ASSERT(current != mdev->worker.task);
-               wait_for_completion(&done);
-       }
-
-abort:
-       if (f & CS_SERIALIZE)
-               mutex_unlock(&mdev->state_mutex);
-
-       return rv;
-}
-
-/**
- * _drbd_request_state() - Request a state change (with flags)
- * @mdev:      DRBD device.
- * @mask:      mask of state bits to change.
- * @val:       value of new state bits.
- * @f:         flags
- *
- * Cousin of drbd_request_state(), useful with the CS_WAIT_COMPLETE
- * flag, or when logging of failed state change requests is not desired.
- */
-enum drbd_state_rv
-_drbd_request_state(struct drbd_conf *mdev, union drbd_state mask,
-                   union drbd_state val, enum chg_state_flags f)
-{
-       enum drbd_state_rv rv;
-
-       wait_event(mdev->state_wait,
-                  (rv = drbd_req_state(mdev, mask, val, f)) != SS_IN_TRANSIENT_STATE);
-
-       return rv;
-}
-
-static void print_st(struct drbd_conf *mdev, char *name, union drbd_state ns)
-{
-       dev_err(DEV, " %s = { cs:%s ro:%s/%s ds:%s/%s %c%c%c%c }\n",
-           name,
-           drbd_conn_str(ns.conn),
-           drbd_role_str(ns.role),
-           drbd_role_str(ns.peer),
-           drbd_disk_str(ns.disk),
-           drbd_disk_str(ns.pdsk),
-           is_susp(ns) ? 's' : 'r',
-           ns.aftr_isp ? 'a' : '-',
-           ns.peer_isp ? 'p' : '-',
-           ns.user_isp ? 'u' : '-'
-           );
-}
-
-void print_st_err(struct drbd_conf *mdev, union drbd_state os,
-                 union drbd_state ns, enum drbd_state_rv err)
-{
-       if (err == SS_IN_TRANSIENT_STATE)
-               return;
-       dev_err(DEV, "State change failed: %s\n", drbd_set_st_err_str(err));
-       print_st(mdev, " state", os);
-       print_st(mdev, "wanted", ns);
-}
-
-
-/**
- * is_valid_state() - Returns an SS_ error code if ns is not valid
- * @mdev:      DRBD device.
- * @ns:                State to consider.
- */
-static enum drbd_state_rv
-is_valid_state(struct drbd_conf *mdev, union drbd_state ns)
-{
-       /* See drbd_state_sw_errors in drbd_strings.c */
-
-       enum drbd_fencing_p fp;
-       enum drbd_state_rv rv = SS_SUCCESS;
-
-       fp = FP_DONT_CARE;
-       if (get_ldev(mdev)) {
-               fp = mdev->ldev->dc.fencing;
-               put_ldev(mdev);
-       }
-
-       if (get_net_conf(mdev)) {
-               if (!mdev->net_conf->two_primaries &&
-                   ns.role == R_PRIMARY && ns.peer == R_PRIMARY)
-                       rv = SS_TWO_PRIMARIES;
-               put_net_conf(mdev);
-       }
-
-       if (rv <= 0)
-               /* already found a reason to abort */;
-       else if (ns.role == R_SECONDARY && mdev->open_cnt)
-               rv = SS_DEVICE_IN_USE;
-
-       else if (ns.role == R_PRIMARY && ns.conn < C_CONNECTED && ns.disk < D_UP_TO_DATE)
-               rv = SS_NO_UP_TO_DATE_DISK;
-
-       else if (fp >= FP_RESOURCE &&
-                ns.role == R_PRIMARY && ns.conn < C_CONNECTED && ns.pdsk >= D_UNKNOWN)
-               rv = SS_PRIMARY_NOP;
-
-       else if (ns.role == R_PRIMARY && ns.disk <= D_INCONSISTENT && ns.pdsk <= D_INCONSISTENT)
-               rv = SS_NO_UP_TO_DATE_DISK;
-
-       else if (ns.conn > C_CONNECTED && ns.disk < D_INCONSISTENT)
-               rv = SS_NO_LOCAL_DISK;
-
-       else if (ns.conn > C_CONNECTED && ns.pdsk < D_INCONSISTENT)
-               rv = SS_NO_REMOTE_DISK;
-
-       else if (ns.conn > C_CONNECTED && ns.disk < D_UP_TO_DATE && ns.pdsk < D_UP_TO_DATE)
-               rv = SS_NO_UP_TO_DATE_DISK;
-
-       else if ((ns.conn == C_CONNECTED ||
-                 ns.conn == C_WF_BITMAP_S ||
-                 ns.conn == C_SYNC_SOURCE ||
-                 ns.conn == C_PAUSED_SYNC_S) &&
-                 ns.disk == D_OUTDATED)
-               rv = SS_CONNECTED_OUTDATES;
-
-       else if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) &&
-                (mdev->sync_conf.verify_alg[0] == 0))
-               rv = SS_NO_VERIFY_ALG;
-
-       else if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) &&
-                 mdev->agreed_pro_version < 88)
-               rv = SS_NOT_SUPPORTED;
-
-       else if (ns.conn >= C_CONNECTED && ns.pdsk == D_UNKNOWN)
-               rv = SS_CONNECTED_OUTDATES;
-
-       return rv;
-}
-
-/**
- * is_valid_state_transition() - Returns an SS_ error code if the state transition is not possible
- * @mdev:      DRBD device.
- * @ns:                new state.
- * @os:                old state.
- */
-static enum drbd_state_rv
-is_valid_state_transition(struct drbd_conf *mdev, union drbd_state ns,
-                         union drbd_state os)
-{
-       enum drbd_state_rv rv = SS_SUCCESS;
-
-       if ((ns.conn == C_STARTING_SYNC_T || ns.conn == C_STARTING_SYNC_S) &&
-           os.conn > C_CONNECTED)
-               rv = SS_RESYNC_RUNNING;
-
-       if (ns.conn == C_DISCONNECTING && os.conn == C_STANDALONE)
-               rv = SS_ALREADY_STANDALONE;
-
-       if (ns.disk > D_ATTACHING && os.disk == D_DISKLESS)
-               rv = SS_IS_DISKLESS;
-
-       if (ns.conn == C_WF_CONNECTION && os.conn < C_UNCONNECTED)
-               rv = SS_NO_NET_CONFIG;
-
-       if (ns.disk == D_OUTDATED && os.disk < D_OUTDATED && os.disk != D_ATTACHING)
-               rv = SS_LOWER_THAN_OUTDATED;
-
-       if (ns.conn == C_DISCONNECTING && os.conn == C_UNCONNECTED)
-               rv = SS_IN_TRANSIENT_STATE;
-
-       if (ns.conn == os.conn && ns.conn == C_WF_REPORT_PARAMS)
-               rv = SS_IN_TRANSIENT_STATE;
-
-       /* While establishing a connection only allow cstate to change.
-          Delay/refuse role changes, detach attach etc... */
-       if (drbd_test_flag(mdev, STATE_SENT) &&
-           !(os.conn == C_WF_REPORT_PARAMS ||
-             (ns.conn == C_WF_REPORT_PARAMS && os.conn == C_WF_CONNECTION)))
-               rv = SS_IN_TRANSIENT_STATE;
-
-       if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) && os.conn < C_CONNECTED)
-               rv = SS_NEED_CONNECTION;
-
-       if ((ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T) &&
-           ns.conn != os.conn && os.conn > C_CONNECTED)
-               rv = SS_RESYNC_RUNNING;
-
-       if ((ns.conn == C_STARTING_SYNC_S || ns.conn == C_STARTING_SYNC_T) &&
-           os.conn < C_CONNECTED)
-               rv = SS_NEED_CONNECTION;
-
-       if ((ns.conn == C_SYNC_TARGET || ns.conn == C_SYNC_SOURCE)
-           && os.conn < C_WF_REPORT_PARAMS)
-               rv = SS_NEED_CONNECTION; /* No NetworkFailure -> SyncTarget etc... */
-
-       return rv;
-}
-
-static void print_sanitize_warnings(struct drbd_conf *mdev, enum sanitize_state_warnings warn)
-{
-       static const char *msg_table[] = {
-               [NO_WARNING] = "",
-               [ABORTED_ONLINE_VERIFY] = "Online-verify aborted.",
-               [ABORTED_RESYNC] = "Resync aborted.",
-               [CONNECTION_LOST_NEGOTIATING] = "Connection lost while negotiating, no data!",
-               [IMPLICITLY_UPGRADED_DISK] = "Implicitly upgraded disk",
-               [IMPLICITLY_UPGRADED_PDSK] = "Implicitly upgraded pdsk",
-       };
-
-       if (warn != NO_WARNING)
-               dev_warn(DEV, "%s\n", msg_table[warn]);
-}
-
-/**
- * sanitize_state() - Resolves implicitly necessary additional changes to a state transition
- * @mdev:      DRBD device.
- * @os:                old state.
- * @ns:                new state.
- * @warn_sync_abort:
- *
- * When we loose connection, we have to set the state of the peers disk (pdsk)
- * to D_UNKNOWN. This rule and many more along those lines are in this function.
- */
-static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state os,
-                                      union drbd_state ns, enum sanitize_state_warnings *warn)
-{
-       enum drbd_fencing_p fp;
-       enum drbd_disk_state disk_min, disk_max, pdsk_min, pdsk_max;
-
-       if (warn)
-               *warn = NO_WARNING;
-
-       fp = FP_DONT_CARE;
-       if (get_ldev(mdev)) {
-               fp = mdev->ldev->dc.fencing;
-               put_ldev(mdev);
-       }
-
-       /* Disallow Network errors to configure a device's network part */
-       if ((ns.conn >= C_TIMEOUT && ns.conn <= C_TEAR_DOWN) &&
-           os.conn <= C_DISCONNECTING)
-               ns.conn = os.conn;
-
-       /* After a network error (+C_TEAR_DOWN) only C_UNCONNECTED or C_DISCONNECTING can follow.
-        * If you try to go into some Sync* state, that shall fail (elsewhere). */
-       if (os.conn >= C_TIMEOUT && os.conn <= C_TEAR_DOWN &&
-           ns.conn != C_UNCONNECTED && ns.conn != C_DISCONNECTING && ns.conn <= C_CONNECTED)
-               ns.conn = os.conn;
-
-       /* we cannot fail (again) if we already detached */
-       if (ns.disk == D_FAILED && os.disk == D_DISKLESS)
-               ns.disk = D_DISKLESS;
-
-       /* After C_DISCONNECTING only C_STANDALONE may follow */
-       if (os.conn == C_DISCONNECTING && ns.conn != C_STANDALONE)
-               ns.conn = os.conn;
-
-       if (ns.conn < C_CONNECTED) {
-               ns.peer_isp = 0;
-               ns.peer = R_UNKNOWN;
-               if (ns.pdsk > D_UNKNOWN || ns.pdsk < D_INCONSISTENT)
-                       ns.pdsk = D_UNKNOWN;
-       }
-
-       /* Clear the aftr_isp when becoming unconfigured */
-       if (ns.conn == C_STANDALONE && ns.disk == D_DISKLESS && ns.role == R_SECONDARY)
-               ns.aftr_isp = 0;
-
-       /* Abort resync if a disk fails/detaches */
-       if (os.conn > C_CONNECTED && ns.conn > C_CONNECTED &&
-           (ns.disk <= D_FAILED || ns.pdsk <= D_FAILED)) {
-               if (warn)
-                       *warn = os.conn == C_VERIFY_S || os.conn == C_VERIFY_T ?
-                               ABORTED_ONLINE_VERIFY : ABORTED_RESYNC;
-               ns.conn = C_CONNECTED;
-       }
-
-       /* Connection breaks down before we finished "Negotiating" */
-       if (ns.conn < C_CONNECTED && ns.disk == D_NEGOTIATING &&
-           get_ldev_if_state(mdev, D_NEGOTIATING)) {
-               if (mdev->ed_uuid == mdev->ldev->md.uuid[UI_CURRENT]) {
-                       ns.disk = mdev->new_state_tmp.disk;
-                       ns.pdsk = mdev->new_state_tmp.pdsk;
-               } else {
-                       if (warn)
-                               *warn = CONNECTION_LOST_NEGOTIATING;
-                       ns.disk = D_DISKLESS;
-                       ns.pdsk = D_UNKNOWN;
-               }
-               put_ldev(mdev);
-       }
-
-       /* D_CONSISTENT and D_OUTDATED vanish when we get connected */
-       if (ns.conn >= C_CONNECTED && ns.conn < C_AHEAD) {
-               if (ns.disk == D_CONSISTENT || ns.disk == D_OUTDATED)
-                       ns.disk = D_UP_TO_DATE;
-               if (ns.pdsk == D_CONSISTENT || ns.pdsk == D_OUTDATED)
-                       ns.pdsk = D_UP_TO_DATE;
-       }
-
-       /* Implications of the connection stat on the disk states */
-       disk_min = D_DISKLESS;
-       disk_max = D_UP_TO_DATE;
-       pdsk_min = D_INCONSISTENT;
-       pdsk_max = D_UNKNOWN;
-       switch ((enum drbd_conns)ns.conn) {
-       case C_WF_BITMAP_T:
-       case C_PAUSED_SYNC_T:
-       case C_STARTING_SYNC_T:
-       case C_WF_SYNC_UUID:
-       case C_BEHIND:
-               disk_min = D_INCONSISTENT;
-               disk_max = D_OUTDATED;
-               pdsk_min = D_UP_TO_DATE;
-               pdsk_max = D_UP_TO_DATE;
-               break;
-       case C_VERIFY_S:
-       case C_VERIFY_T:
-               disk_min = D_UP_TO_DATE;
-               disk_max = D_UP_TO_DATE;
-               pdsk_min = D_UP_TO_DATE;
-               pdsk_max = D_UP_TO_DATE;
-               break;
-       case C_CONNECTED:
-               disk_min = D_DISKLESS;
-               disk_max = D_UP_TO_DATE;
-               pdsk_min = D_DISKLESS;
-               pdsk_max = D_UP_TO_DATE;
-               break;
-       case C_WF_BITMAP_S:
-       case C_PAUSED_SYNC_S:
-       case C_STARTING_SYNC_S:
-       case C_AHEAD:
-               disk_min = D_UP_TO_DATE;
-               disk_max = D_UP_TO_DATE;
-               pdsk_min = D_INCONSISTENT;
-               pdsk_max = D_CONSISTENT; /* D_OUTDATED would be nice. But explicit outdate necessary*/
-               break;
-       case C_SYNC_TARGET:
-               disk_min = D_INCONSISTENT;
-               disk_max = D_INCONSISTENT;
-               pdsk_min = D_UP_TO_DATE;
-               pdsk_max = D_UP_TO_DATE;
-               break;
-       case C_SYNC_SOURCE:
-               disk_min = D_UP_TO_DATE;
-               disk_max = D_UP_TO_DATE;
-               pdsk_min = D_INCONSISTENT;
-               pdsk_max = D_INCONSISTENT;
-               break;
-       case C_STANDALONE:
-       case C_DISCONNECTING:
-       case C_UNCONNECTED:
-       case C_TIMEOUT:
-       case C_BROKEN_PIPE:
-       case C_NETWORK_FAILURE:
-       case C_PROTOCOL_ERROR:
-       case C_TEAR_DOWN:
-       case C_WF_CONNECTION:
-       case C_WF_REPORT_PARAMS:
-       case C_MASK:
-               break;
-       }
-       if (ns.disk > disk_max)
-               ns.disk = disk_max;
-
-       if (ns.disk < disk_min) {
-               if (warn)
-                       *warn = IMPLICITLY_UPGRADED_DISK;
-               ns.disk = disk_min;
-       }
-       if (ns.pdsk > pdsk_max)
-               ns.pdsk = pdsk_max;
-
-       if (ns.pdsk < pdsk_min) {
-               if (warn)
-                       *warn = IMPLICITLY_UPGRADED_PDSK;
-               ns.pdsk = pdsk_min;
-       }
-
-       if (fp == FP_STONITH &&
-           (ns.role == R_PRIMARY && ns.conn < C_CONNECTED && ns.pdsk > D_OUTDATED) &&
-           !(os.role == R_PRIMARY && os.conn < C_CONNECTED && os.pdsk > D_OUTDATED))
-               ns.susp_fen = 1; /* Suspend IO while fence-peer handler runs (peer lost) */
-
-       if (mdev->sync_conf.on_no_data == OND_SUSPEND_IO &&
-           (ns.role == R_PRIMARY && ns.disk < D_UP_TO_DATE && ns.pdsk < D_UP_TO_DATE) &&
-           !(os.role == R_PRIMARY && os.disk < D_UP_TO_DATE && os.pdsk < D_UP_TO_DATE))
-               ns.susp_nod = 1; /* Suspend IO while no data available (no accessible data available) */
-
-       if (ns.aftr_isp || ns.peer_isp || ns.user_isp) {
-               if (ns.conn == C_SYNC_SOURCE)
-                       ns.conn = C_PAUSED_SYNC_S;
-               if (ns.conn == C_SYNC_TARGET)
-                       ns.conn = C_PAUSED_SYNC_T;
-       } else {
-               if (ns.conn == C_PAUSED_SYNC_S)
-                       ns.conn = C_SYNC_SOURCE;
-               if (ns.conn == C_PAUSED_SYNC_T)
-                       ns.conn = C_SYNC_TARGET;
-       }
-
-       return ns;
-}
-
-/* helper for __drbd_set_state */
-static void set_ov_position(struct drbd_conf *mdev, enum drbd_conns cs)
-{
-       if (mdev->agreed_pro_version < 90)
-               mdev->ov_start_sector = 0;
-       mdev->rs_total = drbd_bm_bits(mdev);
-       mdev->ov_position = 0;
-       if (cs == C_VERIFY_T) {
-               /* starting online verify from an arbitrary position
-                * does not fit well into the existing protocol.
-                * on C_VERIFY_T, we initialize ov_left and friends
-                * implicitly in receive_DataRequest once the
-                * first P_OV_REQUEST is received */
-               mdev->ov_start_sector = ~(sector_t)0;
-       } else {
-               unsigned long bit = BM_SECT_TO_BIT(mdev->ov_start_sector);
-               if (bit >= mdev->rs_total) {
-                       mdev->ov_start_sector =
-                               BM_BIT_TO_SECT(mdev->rs_total - 1);
-                       mdev->rs_total = 1;
-               } else
-                       mdev->rs_total -= bit;
-               mdev->ov_position = mdev->ov_start_sector;
-       }
-       mdev->ov_left = mdev->rs_total;
-}
-
-static void drbd_resume_al(struct drbd_conf *mdev)
-{
-       if (drbd_test_and_clear_flag(mdev, AL_SUSPENDED))
-               dev_info(DEV, "Resumed AL updates\n");
-}
-
-/**
- * __drbd_set_state() - Set a new DRBD state
- * @mdev:      DRBD device.
- * @ns:                new state.
- * @flags:     Flags
- * @done:      Optional completion, that will get completed after the after_state_ch() finished
- *
- * Caller needs to hold req_lock, and global_state_lock. Do not call directly.
- */
-enum drbd_state_rv
-__drbd_set_state(struct drbd_conf *mdev, union drbd_state ns,
-                enum chg_state_flags flags, struct completion *done)
-{
-       union drbd_state os;
-       enum drbd_state_rv rv = SS_SUCCESS;
-       enum sanitize_state_warnings ssw;
-       struct after_state_chg_work *ascw;
-
-       os = mdev->state;
-
-       ns = sanitize_state(mdev, os, ns, &ssw);
-
-       if (ns.i == os.i)
-               return SS_NOTHING_TO_DO;
-
-       if (!(flags & CS_HARD)) {
-               /*  pre-state-change checks ; only look at ns  */
-               /* See drbd_state_sw_errors in drbd_strings.c */
-
-               rv = is_valid_state(mdev, ns);
-               if (rv < SS_SUCCESS) {
-                       /* If the old state was illegal as well, then let
-                          this happen...*/
-
-                       if (is_valid_state(mdev, os) == rv)
-                               rv = is_valid_state_transition(mdev, ns, os);
-               } else
-                       rv = is_valid_state_transition(mdev, ns, os);
-       }
-
-       if (rv < SS_SUCCESS) {
-               if (flags & CS_VERBOSE)
-                       print_st_err(mdev, os, ns, rv);
-               return rv;
-       }
-
-       print_sanitize_warnings(mdev, ssw);
-
-       {
-       char *pbp, pb[300];
-       pbp = pb;
-       *pbp = 0;
-       if (ns.role != os.role)
-               pbp += sprintf(pbp, "role( %s -> %s ) ",
-                              drbd_role_str(os.role),
-                              drbd_role_str(ns.role));
-       if (ns.peer != os.peer)
-               pbp += sprintf(pbp, "peer( %s -> %s ) ",
-                              drbd_role_str(os.peer),
-                              drbd_role_str(ns.peer));
-       if (ns.conn != os.conn)
-               pbp += sprintf(pbp, "conn( %s -> %s ) ",
-                              drbd_conn_str(os.conn),
-                              drbd_conn_str(ns.conn));
-       if (ns.disk != os.disk)
-               pbp += sprintf(pbp, "disk( %s -> %s ) ",
-                              drbd_disk_str(os.disk),
-                              drbd_disk_str(ns.disk));
-       if (ns.pdsk != os.pdsk)
-               pbp += sprintf(pbp, "pdsk( %s -> %s ) ",
-                              drbd_disk_str(os.pdsk),
-                              drbd_disk_str(ns.pdsk));
-       if (is_susp(ns) != is_susp(os))
-               pbp += sprintf(pbp, "susp( %d -> %d ) ",
-                              is_susp(os),
-                              is_susp(ns));
-       if (ns.aftr_isp != os.aftr_isp)
-               pbp += sprintf(pbp, "aftr_isp( %d -> %d ) ",
-                              os.aftr_isp,
-                              ns.aftr_isp);
-       if (ns.peer_isp != os.peer_isp)
-               pbp += sprintf(pbp, "peer_isp( %d -> %d ) ",
-                              os.peer_isp,
-                              ns.peer_isp);
-       if (ns.user_isp != os.user_isp)
-               pbp += sprintf(pbp, "user_isp( %d -> %d ) ",
-                              os.user_isp,
-                              ns.user_isp);
-       dev_info(DEV, "%s\n", pb);
-       }
-
-       /* solve the race between becoming unconfigured,
-        * worker doing the cleanup, and
-        * admin reconfiguring us:
-        * on (re)configure, first set CONFIG_PENDING,
-        * then wait for a potentially exiting worker,
-        * start the worker, and schedule one no_op.
-        * then proceed with configuration.
-        */
-       if (ns.disk == D_DISKLESS &&
-           ns.conn == C_STANDALONE &&
-           ns.role == R_SECONDARY &&
-           !drbd_test_and_set_flag(mdev, CONFIG_PENDING))
-               drbd_set_flag(mdev, DEVICE_DYING);
-
-       /* if we are going -> D_FAILED or D_DISKLESS, grab one extra reference
-        * on the ldev here, to be sure the transition -> D_DISKLESS resp.
-        * drbd_ldev_destroy() won't happen before our corresponding
-        * after_state_ch works run, where we put_ldev again. */
-       if ((os.disk != D_FAILED && ns.disk == D_FAILED) ||
-           (os.disk != D_DISKLESS && ns.disk == D_DISKLESS))
-               atomic_inc(&mdev->local_cnt);
-
-       mdev->state = ns;
-
-       if (os.disk == D_ATTACHING && ns.disk >= D_NEGOTIATING)
-               drbd_print_uuids(mdev, "attached to UUIDs");
-
-       wake_up(&mdev->misc_wait);
-       wake_up(&mdev->state_wait);
-
-       /* Aborted verify run, or we reached the stop sector.
-        * Log the last position, unless end-of-device. */
-       if ((os.conn == C_VERIFY_S || os.conn == C_VERIFY_T) &&
-           ns.conn <= C_CONNECTED) {
-               mdev->ov_start_sector =
-                       BM_BIT_TO_SECT(drbd_bm_bits(mdev) - mdev->ov_left);
-               if (mdev->ov_left)
-                       dev_info(DEV, "Online Verify reached sector %llu\n",
-                               (unsigned long long)mdev->ov_start_sector);
-       }
-
-       if ((os.conn == C_PAUSED_SYNC_T || os.conn == C_PAUSED_SYNC_S) &&
-           (ns.conn == C_SYNC_TARGET  || ns.conn == C_SYNC_SOURCE)) {
-               dev_info(DEV, "Syncer continues.\n");
-               mdev->rs_paused += (long)jiffies
-                                 -(long)mdev->rs_mark_time[mdev->rs_last_mark];
-               if (ns.conn == C_SYNC_TARGET)
-                       mod_timer(&mdev->resync_timer, jiffies);
-       }
-
-       if ((os.conn == C_SYNC_TARGET  || os.conn == C_SYNC_SOURCE) &&
-           (ns.conn == C_PAUSED_SYNC_T || ns.conn == C_PAUSED_SYNC_S)) {
-               dev_info(DEV, "Resync suspended\n");
-               mdev->rs_mark_time[mdev->rs_last_mark] = jiffies;
-       }
-
-       if (os.conn == C_CONNECTED &&
-           (ns.conn == C_VERIFY_S || ns.conn == C_VERIFY_T)) {
-               unsigned long now = jiffies;
-               int i;
-
-               set_ov_position(mdev, ns.conn);
-               mdev->rs_start = now;
-               mdev->rs_last_events = 0;
-               mdev->rs_last_sect_ev = 0;
-               mdev->ov_last_oos_size = 0;
-               mdev->ov_last_oos_start = 0;
-
-               for (i = 0; i < DRBD_SYNC_MARKS; i++) {
-                       mdev->rs_mark_left[i] = mdev->ov_left;
-                       mdev->rs_mark_time[i] = now;
-               }
-
-               drbd_rs_controller_reset(mdev);
-
-               if (ns.conn == C_VERIFY_S) {
-                       dev_info(DEV, "Starting Online Verify from sector %llu\n",
-                                       (unsigned long long)mdev->ov_position);
-                       mod_timer(&mdev->resync_timer, jiffies);
-               }
-       }
-
-       if (get_ldev(mdev)) {
-               u32 mdf = mdev->ldev->md.flags & ~(MDF_CONSISTENT|MDF_PRIMARY_IND|
-                                                MDF_CONNECTED_IND|MDF_WAS_UP_TO_DATE|
-                                                MDF_PEER_OUT_DATED|MDF_CRASHED_PRIMARY);
-
-               if (drbd_test_flag(mdev, CRASHED_PRIMARY))
-                       mdf |= MDF_CRASHED_PRIMARY;
-               if (mdev->state.role == R_PRIMARY ||
-                   (mdev->state.pdsk < D_INCONSISTENT && mdev->state.peer == R_PRIMARY))
-                       mdf |= MDF_PRIMARY_IND;
-               if (mdev->state.conn > C_WF_REPORT_PARAMS)
-                       mdf |= MDF_CONNECTED_IND;
-               if (mdev->state.disk > D_INCONSISTENT)
-                       mdf |= MDF_CONSISTENT;
-               if (mdev->state.disk > D_OUTDATED)
-                       mdf |= MDF_WAS_UP_TO_DATE;
-               if (mdev->state.pdsk <= D_OUTDATED && mdev->state.pdsk >= D_INCONSISTENT)
-                       mdf |= MDF_PEER_OUT_DATED;
-               if (mdf != mdev->ldev->md.flags) {
-                       mdev->ldev->md.flags = mdf;
-                       drbd_md_mark_dirty(mdev);
-               }
-               if (os.disk < D_CONSISTENT && ns.disk >= D_CONSISTENT)
-                       drbd_set_ed_uuid(mdev, mdev->ldev->md.uuid[UI_CURRENT]);
-               put_ldev(mdev);
-       }
-
-       /* Peer was forced D_UP_TO_DATE & R_PRIMARY, consider to resync */
-       if (os.disk == D_INCONSISTENT && os.pdsk == D_INCONSISTENT &&
-           os.peer == R_SECONDARY && ns.peer == R_PRIMARY)
-               drbd_set_flag(mdev, CONSIDER_RESYNC);
-
-       /* Receiver should clean up itself */
-       if (os.conn != C_DISCONNECTING && ns.conn == C_DISCONNECTING)
-               drbd_thread_stop_nowait(&mdev->receiver);
-
-       /* Now the receiver finished cleaning up itself, it should die */
-       if (os.conn != C_STANDALONE && ns.conn == C_STANDALONE)
-               drbd_thread_stop_nowait(&mdev->receiver);
-
-       /* Upon network failure, we need to restart the receiver. */
-       if (os.conn > C_WF_CONNECTION &&
-           ns.conn <= C_TEAR_DOWN && ns.conn >= C_TIMEOUT)
-               drbd_thread_restart_nowait(&mdev->receiver);
-
-       /* Resume AL writing if we get a connection */
-       if (os.conn < C_CONNECTED && ns.conn >= C_CONNECTED)
-               drbd_resume_al(mdev);
-
-       /* remember last connect and attach times so request_timer_fn() won't
-        * kill newly established sessions while we are still trying to thaw
-        * previously frozen IO */
-       if (os.conn != C_WF_REPORT_PARAMS && ns.conn == C_WF_REPORT_PARAMS)
-               mdev->last_reconnect_jif = jiffies;
-       if ((os.disk == D_ATTACHING || os.disk == D_NEGOTIATING) &&
-           ns.disk > D_NEGOTIATING)
-               mdev->last_reattach_jif = jiffies;
-
-       ascw = kmalloc(sizeof(*ascw), GFP_ATOMIC);
-       if (ascw) {
-               ascw->os = os;
-               ascw->ns = ns;
-               ascw->flags = flags;
-               ascw->w.cb = w_after_state_ch;
-               ascw->done = done;
-               drbd_queue_work(&mdev->data.work, &ascw->w);
-       } else {
-               dev_warn(DEV, "Could not kmalloc an ascw\n");
-       }
-
-       return rv;
-}
-
-static int w_after_state_ch(struct drbd_conf *mdev, struct drbd_work *w, int unused)
-{
-       struct after_state_chg_work *ascw =
-               container_of(w, struct after_state_chg_work, w);
-       after_state_ch(mdev, ascw->os, ascw->ns, ascw->flags);
-       if (ascw->flags & CS_WAIT_COMPLETE) {
-               D_ASSERT(ascw->done != NULL);
-               complete(ascw->done);
-       }
-       kfree(ascw);
-
-       return 1;
-}
-
-static void abw_start_sync(struct drbd_conf *mdev, int rv)
-{
-       if (rv) {
-               dev_err(DEV, "Writing the bitmap failed not starting resync.\n");
-               _drbd_request_state(mdev, NS(conn, C_CONNECTED), CS_VERBOSE);
-               return;
-       }
-
-       switch (mdev->state.conn) {
-       case C_STARTING_SYNC_T:
-               _drbd_request_state(mdev, NS(conn, C_WF_SYNC_UUID), CS_VERBOSE);
-               break;
-       case C_STARTING_SYNC_S:
-               drbd_start_resync(mdev, C_SYNC_SOURCE);
-               break;
-       }
-}
-
-int drbd_bitmap_io_from_worker(struct drbd_conf *mdev,
-               int (*io_fn)(struct drbd_conf *),
-               char *why, enum bm_flag flags)
-{
-       int rv;
-
-       D_ASSERT(current == mdev->worker.task);
-
-       /* open coded non-blocking drbd_suspend_io(mdev); */
-       drbd_set_flag(mdev, SUSPEND_IO);
+};
 
-       drbd_bm_lock(mdev, why, flags);
-       rv = io_fn(mdev);
-       drbd_bm_unlock(mdev);
+struct bio *bio_alloc_drbd(gfp_t gfp_mask)
+{
+       struct bio *bio;
 
-       drbd_resume_io(mdev);
+       if (!drbd_md_io_bio_set)
+               return bio_alloc(gfp_mask, 1);
 
-       return rv;
+       bio = bio_alloc_bioset(gfp_mask, 1, drbd_md_io_bio_set);
+       if (!bio)
+               return NULL;
+       return bio;
 }
 
-/**
- * after_state_ch() - Perform after state change actions that may sleep
- * @mdev:      DRBD device.
- * @os:                old state.
- * @ns:                new state.
- * @flags:     Flags
+#ifdef __CHECKER__
+/* When checking with sparse, and this is an inline function, sparse will
+   give tons of false positives. When this is a real functions sparse works.
  */
-static void after_state_ch(struct drbd_conf *mdev, union drbd_state os,
-                          union drbd_state ns, enum chg_state_flags flags)
+int _get_ldev_if_state(struct drbd_conf *mdev, enum drbd_disk_state mins)
 {
-       enum drbd_fencing_p fp;
-       enum drbd_req_event what = nothing;
-       union drbd_state nsm = (union drbd_state){ .i = -1 };
-
-       if (os.conn != C_CONNECTED && ns.conn == C_CONNECTED) {
-               drbd_clear_flag(mdev, CRASHED_PRIMARY);
-               if (mdev->p_uuid)
-                       mdev->p_uuid[UI_FLAGS] &= ~((u64)2);
-       }
+       int io_allowed;
 
-       fp = FP_DONT_CARE;
-       if (get_ldev(mdev)) {
-               fp = mdev->ldev->dc.fencing;
-               put_ldev(mdev);
+       atomic_inc(&mdev->local_cnt);
+       io_allowed = (mdev->state.disk >= mins);
+       if (!io_allowed) {
+               if (atomic_dec_and_test(&mdev->local_cnt))
+                       wake_up(&mdev->misc_wait);
        }
+       return io_allowed;
+}
 
-       /* Inform userspace about the change... */
-       drbd_bcast_state(mdev, ns);
-
-       if (!(os.role == R_PRIMARY && os.disk < D_UP_TO_DATE && os.pdsk < D_UP_TO_DATE) &&
-           (ns.role == R_PRIMARY && ns.disk < D_UP_TO_DATE && ns.pdsk < D_UP_TO_DATE))
-               drbd_khelper(mdev, "pri-on-incon-degr");
-
-       /* Here we have the actions that are performed after a
-          state change. This function might sleep */
-
-       if (os.disk <= D_NEGOTIATING && ns.disk > D_NEGOTIATING)
-               mod_timer(&mdev->request_timer, jiffies + HZ);
-
-       nsm.i = -1;
-       if (ns.susp_nod) {
-               if (os.conn < C_CONNECTED && ns.conn >= C_CONNECTED)
-                       what = resend;
-
-               if ((os.disk == D_ATTACHING || os.disk == D_NEGOTIATING) &&
-                   ns.disk > D_NEGOTIATING)
-                       what = restart_frozen_disk_io;
-
-               if (what != nothing)
-                       nsm.susp_nod = 0;
-       }
+#endif
 
-       if (ns.susp_fen) {
-               /* case1: The outdate peer handler is successful: */
-               if (os.pdsk > D_OUTDATED  && ns.pdsk <= D_OUTDATED) {
-                       if (drbd_test_flag(mdev, NEW_CUR_UUID)) {
-                               drbd_uuid_new_current(mdev);
-                               drbd_clear_flag(mdev, NEW_CUR_UUID);
-                       }
-                       spin_lock_irq(&mdev->req_lock);
-                       _tl_clear(mdev);
-                       _drbd_set_state(_NS(mdev, susp_fen, 0), CS_VERBOSE, NULL);
-                       spin_unlock_irq(&mdev->req_lock);
-               }
-               /* case2: The connection was established again: */
-               if (os.conn < C_CONNECTED && ns.conn >= C_CONNECTED) {
-                       drbd_clear_flag(mdev, NEW_CUR_UUID);
-                       what = resend;
-                       nsm.susp_fen = 0;
+/**
+ * tl_release() - mark as BARRIER_ACKED all requests in the corresponding transfer log epoch
+ * @tconn:     DRBD connection.
+ * @barrier_nr:        Expected identifier of the DRBD write barrier packet.
+ * @set_size:  Expected number of requests before that barrier.
+ *
+ * In case the passed barrier_nr or set_size does not match the oldest
+ * epoch of not yet barrier-acked requests, this function will cause a
+ * termination of the connection.
+ */
+void tl_release(struct drbd_tconn *tconn, unsigned int barrier_nr,
+               unsigned int set_size)
+{
+       struct drbd_request *r;
+       struct drbd_request *req = NULL;
+       int expect_epoch = 0;
+       int expect_size = 0;
+
+       spin_lock_irq(&tconn->req_lock);
+
+       /* find oldest not yet barrier-acked write request,
+        * count writes in its epoch. */
+       list_for_each_entry(r, &tconn->transfer_log, tl_requests) {
+               const unsigned s = r->rq_state;
+               if (!req) {
+                       if (!(s & RQ_WRITE))
+                               continue;
+                       if (!(s & RQ_NET_MASK))
+                               continue;
+                       if (s & RQ_NET_DONE)
+                               continue;
+                       req = r;
+                       expect_epoch = req->epoch;
+                       expect_size ++;
+               } else {
+                       if (r->epoch != expect_epoch)
+                               break;
+                       if (!(s & RQ_WRITE))
+                               continue;
+                       /* if (s & RQ_DONE): not expected */
+                       /* if (!(s & RQ_NET_MASK)): not expected */
+                       expect_size++;
                }
        }
 
-       if (what != nothing) {
-               spin_lock_irq(&mdev->req_lock);
-               _tl_restart(mdev, what);
-               nsm.i &= mdev->state.i;
-               _drbd_set_state(mdev, nsm, CS_VERBOSE, NULL);
-               spin_unlock_irq(&mdev->req_lock);
+       /* first some paranoia code */
+       if (req == NULL) {
+               conn_err(tconn, "BAD! BarrierAck #%u received, but no epoch in tl!?\n",
+                        barrier_nr);
+               goto bail;
        }
-
-       /* Became sync source.  With protocol >= 96, we still need to send out
-        * the sync uuid now. Need to do that before any drbd_send_state, or
-        * the other side may go "paused sync" before receiving the sync uuids,
-        * which is unexpected. */
-       if ((os.conn != C_SYNC_SOURCE && os.conn != C_PAUSED_SYNC_S) &&
-           (ns.conn == C_SYNC_SOURCE || ns.conn == C_PAUSED_SYNC_S) &&
-           mdev->agreed_pro_version >= 96 && get_ldev(mdev)) {
-               drbd_gen_and_send_sync_uuid(mdev);
-               put_ldev(mdev);
+       if (expect_epoch != barrier_nr) {
+               conn_err(tconn, "BAD! BarrierAck #%u received, expected #%u!\n",
+                        barrier_nr, expect_epoch);
+               goto bail;
        }
 
-       /* Do not change the order of the if above and the two below... */
-       if (os.pdsk == D_DISKLESS && ns.pdsk > D_DISKLESS) {      /* attach on the peer */
-               /* we probably will start a resync soon.
-                * make sure those things are properly reset. */
-               mdev->rs_total = 0;
-               mdev->rs_failed = 0;
-               atomic_set(&mdev->rs_pending_cnt, 0);
-               drbd_rs_cancel_all(mdev);
-
-               drbd_send_uuids(mdev);
-               drbd_send_state(mdev, ns);
-       }
-       /* No point in queuing send_bitmap if we don't have a connection
-        * anymore, so check also the _current_ state, not only the new state
-        * at the time this work was queued. */
-       if (os.conn != C_WF_BITMAP_S && ns.conn == C_WF_BITMAP_S &&
-           mdev->state.conn == C_WF_BITMAP_S)
-               drbd_queue_bitmap_io(mdev, &drbd_send_bitmap, NULL,
-                               "send_bitmap (WFBitMapS)",
-                               BM_LOCKED_TEST_ALLOWED);
-
-       /* Lost contact to peer's copy of the data */
-       if ((os.pdsk >= D_INCONSISTENT &&
-            os.pdsk != D_UNKNOWN &&
-            os.pdsk != D_OUTDATED)
-       &&  (ns.pdsk < D_INCONSISTENT ||
-            ns.pdsk == D_UNKNOWN ||
-            ns.pdsk == D_OUTDATED)) {
-               if (get_ldev(mdev)) {
-                       if ((ns.role == R_PRIMARY || ns.peer == R_PRIMARY) &&
-                           mdev->ldev->md.uuid[UI_BITMAP] == 0 && ns.disk >= D_UP_TO_DATE) {
-                               if (is_susp(mdev->state)) {
-                                       drbd_set_flag(mdev, NEW_CUR_UUID);
-                               } else {
-                                       drbd_uuid_new_current(mdev);
-                                       drbd_send_uuids(mdev);
-                               }
-                       }
-                       put_ldev(mdev);
-               }
+       if (expect_size != set_size) {
+               conn_err(tconn, "BAD! BarrierAck #%u received with n_writes=%u, expected n_writes=%u!\n",
+                        barrier_nr, set_size, expect_size);
+               goto bail;
        }
 
-       if (ns.pdsk < D_INCONSISTENT && get_ldev(mdev)) {
-               if (os.peer == R_SECONDARY && ns.peer == R_PRIMARY &&
-                   mdev->ldev->md.uuid[UI_BITMAP] == 0 && ns.disk >= D_UP_TO_DATE) {
-                       drbd_uuid_new_current(mdev);
-                       drbd_send_uuids(mdev);
-               }
-               /* D_DISKLESS Peer becomes secondary */
-               if (os.peer == R_PRIMARY && ns.peer == R_SECONDARY)
-                       /* We may still be Primary ourselves.
-                        * No harm done if the bitmap still changes,
-                        * redirtied pages will follow later. */
-                       drbd_bitmap_io_from_worker(mdev, &drbd_bm_write,
-                               "demote diskless peer", BM_LOCKED_SET_ALLOWED);
-               put_ldev(mdev);
+       /* Clean up list of requests processed during current epoch. */
+       /* this extra list walk restart is paranoia,
+        * to catch requests being barrier-acked "unexpectedly".
+        * It usually should find the same req again, or some READ preceding it. */
+       list_for_each_entry(req, &tconn->transfer_log, tl_requests)
+               if (req->epoch == expect_epoch)
+                       break;
+       list_for_each_entry_safe_from(req, r, &tconn->transfer_log, tl_requests) {
+               if (req->epoch != expect_epoch)
+                       break;
+               _req_mod(req, BARRIER_ACKED);
        }
+       spin_unlock_irq(&tconn->req_lock);
 
-       /* Write out all changed bits on demote.
-        * Though, no need to da that just yet
-        * if there is a resync going on still */
-       if (os.role == R_PRIMARY && ns.role == R_SECONDARY &&
-               mdev->state.conn <= C_CONNECTED && get_ldev(mdev)) {
-               /* No changes to the bitmap expected this time, so assert that,
-                * even though no harm was done if it did change. */
-               drbd_bitmap_io_from_worker(mdev, &drbd_bm_write,
-                               "demote", BM_LOCKED_TEST_ALLOWED);
-               put_ldev(mdev);
-       }
+       return;
 
-       /* Last part of the attaching process ... */
-       if (ns.conn >= C_CONNECTED &&
-           os.disk == D_ATTACHING && ns.disk == D_NEGOTIATING) {
-               drbd_send_sizes(mdev, 0, 0);  /* to start sync... */
-               drbd_send_uuids(mdev);
-               drbd_send_state(mdev, ns);
-       }
+bail:
+       spin_unlock_irq(&tconn->req_lock);
+       conn_request_state(tconn, NS(conn, C_PROTOCOL_ERROR), CS_HARD);
+}
 
-       /* We want to pause/continue resync, tell peer. */
-       if (ns.conn >= C_CONNECTED &&
-            ((os.aftr_isp != ns.aftr_isp) ||
-             (os.user_isp != ns.user_isp)))
-               drbd_send_state(mdev, ns);
-
-       /* In case one of the isp bits got set, suspend other devices. */
-       if ((!os.aftr_isp && !os.peer_isp && !os.user_isp) &&
-           (ns.aftr_isp || ns.peer_isp || ns.user_isp))
-               suspend_other_sg(mdev);
-
-       /* Make sure the peer gets informed about eventual state
-          changes (ISP bits) while we were in WFReportParams. */
-       if (os.conn == C_WF_REPORT_PARAMS && ns.conn >= C_CONNECTED)
-               drbd_send_state(mdev, ns);
-
-       if (os.conn != C_AHEAD && ns.conn == C_AHEAD)
-               drbd_send_state(mdev, ns);
-
-       /* We are in the progress to start a full sync... */
-       if ((os.conn != C_STARTING_SYNC_T && ns.conn == C_STARTING_SYNC_T) ||
-           (os.conn != C_STARTING_SYNC_S && ns.conn == C_STARTING_SYNC_S))
-               /* no other bitmap changes expected during this phase */
-               drbd_queue_bitmap_io(mdev,
-                       &drbd_bmio_set_n_write, &abw_start_sync,
-                       "set_n_write from StartingSync", BM_LOCKED_TEST_ALLOWED);
-
-       /* We are invalidating our self... */
-       if (os.conn < C_CONNECTED && ns.conn < C_CONNECTED &&
-           os.disk > D_INCONSISTENT && ns.disk == D_INCONSISTENT)
-               /* other bitmap operation expected during this phase */
-               drbd_queue_bitmap_io(mdev, &drbd_bmio_set_n_write, NULL,
-                       "set_n_write from invalidate", BM_LOCKED_MASK);
-
-       /* first half of local IO error, failure to attach,
-        * or administrative detach */
-       if (os.disk != D_FAILED && ns.disk == D_FAILED) {
-               /* corresponding get_ldev was in __drbd_set_state, to serialize
-                * our cleanup here with the transition to D_DISKLESS.
-                * But it is still not safe to dreference ldev here, we may end
-                * up here from a failed attach, before ldev was even set.  */
-               if (mdev->ldev) {
-                       enum drbd_io_error_p eh = mdev->ldev->dc.on_io_error;
-
-                       /* In some setups, this handler triggers a suicide,
-                        * basically mapping IO error to node failure, to
-                        * reduce the number of different failure scenarios.
-                        *
-                        * This handler intentionally runs before we abort IO,
-                        * notify the peer, or try to update our meta data. */
-                       if (eh == EP_CALL_HELPER && drbd_test_flag(mdev, WAS_IO_ERROR))
-                               drbd_khelper(mdev, "local-io-error");
-
-                       /* Immediately allow completion of all application IO,
-                        * that waits for completion from the local disk,
-                        * if this was a force-detach due to disk_timeout
-                        * or administrator request (drbdsetup detach --force).
-                        * Do NOT abort otherwise.
-                        * Aborting local requests may cause serious problems,
-                        * if requests are completed to upper layers already,
-                        * and then later the already submitted local bio completes.
-                        * This can cause DMA into former bio pages that meanwhile
-                        * have been re-used for other things.
-                        * So aborting local requests may cause crashes,
-                        * or even worse, silent data corruption.
-                        */
-                       if (drbd_test_flag(mdev, FORCE_DETACH))
-                               tl_abort_disk_io(mdev);
-
-                       /* current state still has to be D_FAILED,
-                        * there is only one way out: to D_DISKLESS,
-                        * and that may only happen after our put_ldev below. */
-                       if (mdev->state.disk != D_FAILED)
-                               dev_err(DEV,
-                                       "ASSERT FAILED: disk is %s during detach\n",
-                                       drbd_disk_str(mdev->state.disk));
-
-                       if (ns.conn >= C_CONNECTED)
-                               drbd_send_state(mdev, ns);
-
-                       drbd_rs_cancel_all(mdev);
-
-                       /* In case we want to get something to stable storage still,
-                        * this may be the last chance.
-                        * Following put_ldev may transition to D_DISKLESS. */
-                       drbd_md_sync(mdev);
-               }
-               put_ldev(mdev);
-       }
 
-        /* second half of local IO error, failure to attach,
-         * or administrative detach,
-         * after local_cnt references have reached zero again */
-        if (os.disk != D_DISKLESS && ns.disk == D_DISKLESS) {
-                /* We must still be diskless,
-                 * re-attach has to be serialized with this! */
-                if (mdev->state.disk != D_DISKLESS)
-                        dev_err(DEV,
-                                "ASSERT FAILED: disk is %s while going diskless\n",
-                                drbd_disk_str(mdev->state.disk));
-
-               if (ns.conn >= C_CONNECTED)
-                       drbd_send_state(mdev, ns);
-
-               /* corresponding get_ldev in __drbd_set_state
-                * this may finally trigger drbd_ldev_destroy. */
-               put_ldev(mdev);
-       }
+/**
+ * _tl_restart() - Walks the transfer log, and applies an action to all requests
+ * @mdev:      DRBD device.
+ * @what:       The action/event to perform with all request objects
+ *
+ * @what might be one of CONNECTION_LOST_WHILE_PENDING, RESEND, FAIL_FROZEN_DISK_IO,
+ * RESTART_FROZEN_DISK_IO.
+ */
+/* must hold resource->req_lock */
+void _tl_restart(struct drbd_tconn *tconn, enum drbd_req_event what)
+{
+       struct drbd_request *req, *r;
 
-       /* Notify peer that I had a local IO error, and did not detached.. */
-       if (os.disk == D_UP_TO_DATE && ns.disk == D_INCONSISTENT && ns.conn >= C_CONNECTED)
-               drbd_send_state(mdev, ns);
+       list_for_each_entry_safe(req, r, &tconn->transfer_log, tl_requests)
+               _req_mod(req, what);
+}
 
-       /* Disks got bigger while they were detached */
-       if (ns.disk > D_NEGOTIATING && ns.pdsk > D_NEGOTIATING &&
-           drbd_test_and_clear_flag(mdev, RESYNC_AFTER_NEG)) {
-               if (ns.conn == C_CONNECTED)
-                       resync_after_online_grow(mdev);
-       }
+void tl_restart(struct drbd_tconn *tconn, enum drbd_req_event what)
+{
+       spin_lock_irq(&tconn->req_lock);
+       _tl_restart(tconn, what);
+       spin_unlock_irq(&tconn->req_lock);
+}
 
-       /* A resync finished or aborted, wake paused devices... */
-       if ((os.conn > C_CONNECTED && ns.conn <= C_CONNECTED) ||
-           (os.peer_isp && !ns.peer_isp) ||
-           (os.user_isp && !ns.user_isp))
-               resume_next_sg(mdev);
-
-       /* sync target done with resync.  Explicitly notify peer, even though
-        * it should (at least for non-empty resyncs) already know itself. */
-       if (os.disk < D_UP_TO_DATE && os.conn >= C_SYNC_SOURCE && ns.conn == C_CONNECTED)
-               drbd_send_state(mdev, ns);
-
-       /* Verify finished, or reached stop sector.  Peer did not know about
-        * the stop sector, and we may even have changed the stop sector during
-        * verify to interrupt/stop early.  Send the new state. */
-       if (os.conn == C_VERIFY_S && ns.conn == C_CONNECTED
-       && mdev->agreed_pro_version >= 97)
-               drbd_send_state(mdev, ns);
-
-       /* Wake up role changes, that were delayed because of connection establishing */
-       if (os.conn == C_WF_REPORT_PARAMS && ns.conn != C_WF_REPORT_PARAMS) {
-               drbd_clear_flag(mdev, STATE_SENT);
-               wake_up(&mdev->state_wait);
-       }
+/**
+ * tl_clear() - Clears all requests and &struct drbd_tl_epoch objects out of the TL
+ * @mdev:      DRBD device.
+ *
+ * This is called after the connection to the peer was lost. The storage covered
+ * by the requests on the transfer gets marked as our of sync. Called from the
+ * receiver thread and the worker thread.
+ */
+void tl_clear(struct drbd_tconn *tconn)
+{
+       tl_restart(tconn, CONNECTION_LOST_WHILE_PENDING);
+}
 
-       /* This triggers bitmap writeout of potentially still unwritten pages
-        * if the resync finished cleanly, or aborted because of peer disk
-        * failure, or because of connection loss.
-        * For resync aborted because of local disk failure, we cannot do
-        * any bitmap writeout anymore.
-        * No harm done if some bits change during this phase.
-        */
-       if (os.conn > C_CONNECTED && ns.conn <= C_CONNECTED && get_ldev(mdev)) {
-               drbd_queue_bitmap_io(mdev, &drbd_bm_write_copy_pages, NULL,
-                       "write from resync_finished", BM_LOCKED_CHANGE_ALLOWED);
-               put_ldev(mdev);
-       }
+/**
+ * tl_abort_disk_io() - Abort disk I/O for all requests for a certain mdev in the TL
+ * @mdev:      DRBD device.
+ */
+void tl_abort_disk_io(struct drbd_conf *mdev)
+{
+       struct drbd_tconn *tconn = mdev->tconn;
+       struct drbd_request *req, *r;
 
-       /* free tl_hash if we Got thawed and are C_STANDALONE */
-       if (ns.conn == C_STANDALONE && !is_susp(ns) && mdev->tl_hash)
-               drbd_free_tl_hash(mdev);
-
-       /* Upon network connection, we need to start the receiver */
-       if (os.conn == C_STANDALONE && ns.conn == C_UNCONNECTED)
-               drbd_thread_start(&mdev->receiver);
-
-       /* Terminate worker thread if we are unconfigured - it will be
-          restarted as needed... */
-       if (ns.disk == D_DISKLESS &&
-           ns.conn == C_STANDALONE &&
-           ns.role == R_SECONDARY) {
-               if (os.aftr_isp != ns.aftr_isp)
-                       resume_next_sg(mdev);
-               /* set in __drbd_set_state, unless CONFIG_PENDING was set */
-               if (drbd_test_flag(mdev, DEVICE_DYING))
-                       drbd_thread_stop_nowait(&mdev->worker);
+       spin_lock_irq(&tconn->req_lock);
+       list_for_each_entry_safe(req, r, &tconn->transfer_log, tl_requests) {
+               if (!(req->rq_state & RQ_LOCAL_PENDING))
+                       continue;
+               if (req->w.mdev != mdev)
+                       continue;
+               _req_mod(req, ABORT_DISK_IO);
        }
-
-       drbd_md_sync(mdev);
+       spin_unlock_irq(&tconn->req_lock);
 }
 
-
 static int drbd_thread_setup(void *arg)
 {
        struct drbd_thread *thi = (struct drbd_thread *) arg;
-       struct drbd_conf *mdev = thi->mdev;
+       struct drbd_tconn *tconn = thi->tconn;
        unsigned long flags;
        int retval;
 
+       snprintf(current->comm, sizeof(current->comm), "drbd_%c_%s",
+                thi->name[0], thi->tconn->name);
+
 restart:
        retval = thi->function(thi);
 
        spin_lock_irqsave(&thi->t_lock, flags);
 
-       /* if the receiver has been "Exiting", the last thing it did
+       /* if the receiver has been "EXITING", the last thing it did
         * was set the conn state to "StandAlone",
         * if now a re-connect request comes in, conn state goes C_UNCONNECTED,
         * and receiver thread will be "started".
-        * drbd_thread_start needs to set "Restarting" in that case.
+        * drbd_thread_start needs to set "RESTARTING" in that case.
         * t_state check and assignment needs to be within the same spinlock,
-        * so either thread_start sees Exiting, and can remap to Restarting,
-        * or thread_start see None, and can proceed as normal.
+        * so either thread_start sees EXITING, and can remap to RESTARTING,
+        * or thread_start see NONE, and can proceed as normal.
         */
 
-       if (thi->t_state == Restarting) {
-               dev_info(DEV, "Restarting %s\n", current->comm);
-               thi->t_state = Running;
+       if (thi->t_state == RESTARTING) {
+               conn_info(tconn, "Restarting %s thread\n", thi->name);
+               thi->t_state = RUNNING;
                spin_unlock_irqrestore(&thi->t_lock, flags);
                goto restart;
        }
 
        thi->task = NULL;
-       thi->t_state = None;
+       thi->t_state = NONE;
        smp_mb();
-       complete(&thi->stop);
+       complete_all(&thi->stop);
        spin_unlock_irqrestore(&thi->t_lock, flags);
 
-       dev_info(DEV, "Terminating %s\n", current->comm);
+       conn_info(tconn, "Terminating %s\n", current->comm);
 
        /* Release mod reference taken when thread was started */
+
+       kref_put(&tconn->kref, &conn_destroy);
        module_put(THIS_MODULE);
        return retval;
 }
 
-static void drbd_thread_init(struct drbd_conf *mdev, struct drbd_thread *thi,
-                     int (*func) (struct drbd_thread *))
+static void drbd_thread_init(struct drbd_tconn *tconn, struct drbd_thread *thi,
+                            int (*func) (struct drbd_thread *), char *name)
 {
        spin_lock_init(&thi->t_lock);
        thi->task    = NULL;
-       thi->t_state = None;
+       thi->t_state = NONE;
        thi->function = func;
-       thi->mdev = mdev;
+       thi->tconn = tconn;
+       strncpy(thi->name, name, ARRAY_SIZE(thi->name));
 }
 
 int drbd_thread_start(struct drbd_thread *thi)
 {
-       struct drbd_conf *mdev = thi->mdev;
+       struct drbd_tconn *tconn = thi->tconn;
        struct task_struct *nt;
        unsigned long flags;
 
-       const char *me =
-               thi == &mdev->receiver ? "receiver" :
-               thi == &mdev->asender  ? "asender"  :
-               thi == &mdev->worker   ? "worker"   : "NONSENSE";
-
        /* is used from state engine doing drbd_thread_stop_nowait,
         * while holding the req lock irqsave */
        spin_lock_irqsave(&thi->t_lock, flags);
 
        switch (thi->t_state) {
-       case None:
-               dev_info(DEV, "Starting %s thread (from %s [%d])\n",
-                               me, current->comm, current->pid);
+       case NONE:
+               conn_info(tconn, "Starting %s thread (from %s [%d])\n",
+                        thi->name, current->comm, current->pid);
 
                /* Get ref on module for thread - this is released when thread exits */
                if (!try_module_get(THIS_MODULE)) {
-                       dev_err(DEV, "Failed to get module reference in drbd_thread_start\n");
+                       conn_err(tconn, "Failed to get module reference in drbd_thread_start\n");
                        spin_unlock_irqrestore(&thi->t_lock, flags);
                        return false;
                }
 
+               kref_get(&thi->tconn->kref);
+
                init_completion(&thi->stop);
-               D_ASSERT(thi->task == NULL);
                thi->reset_cpu_mask = 1;
-               thi->t_state = Running;
+               thi->t_state = RUNNING;
                spin_unlock_irqrestore(&thi->t_lock, flags);
                flush_signals(current); /* otherw. may get -ERESTARTNOINTR */
 
                nt = kthread_create(drbd_thread_setup, (void *) thi,
-                                   "drbd%d_%s", mdev_to_minor(mdev), me);
+                                   "drbd_%c_%s", thi->name[0], thi->tconn->name);
 
                if (IS_ERR(nt)) {
-                       dev_err(DEV, "Couldn't start thread\n");
+                       conn_err(tconn, "Couldn't start thread\n");
 
+                       kref_put(&tconn->kref, &conn_destroy);
                        module_put(THIS_MODULE);
                        return false;
                }
                spin_lock_irqsave(&thi->t_lock, flags);
                thi->task = nt;
-               thi->t_state = Running;
+               thi->t_state = RUNNING;
                spin_unlock_irqrestore(&thi->t_lock, flags);
                wake_up_process(nt);
                break;
-       case Exiting:
-               thi->t_state = Restarting;
-               dev_info(DEV, "Restarting %s thread (from %s [%d])\n",
-                               me, current->comm, current->pid);
+       case EXITING:
+               thi->t_state = RESTARTING;
+               conn_info(tconn, "Restarting %s thread (from %s [%d])\n",
+                               thi->name, current->comm, current->pid);
                /* fall through */
-       case Running:
-       case Restarting:
+       case RUNNING:
+       case RESTARTING:
        default:
                spin_unlock_irqrestore(&thi->t_lock, flags);
                break;
@@ -1882,12 +447,12 @@ void _drbd_thread_stop(struct drbd_thread *thi, int restart, int wait)
 {
        unsigned long flags;
 
-       enum drbd_thread_state ns = restart ? Restarting : Exiting;
+       enum drbd_thread_state ns = restart ? RESTARTING : EXITING;
 
        /* may be called from state engine, holding the req lock irqsave */
        spin_lock_irqsave(&thi->t_lock, flags);
 
-       if (thi->t_state == None) {
+       if (thi->t_state == NONE) {
                spin_unlock_irqrestore(&thi->t_lock, flags);
                if (restart)
                        drbd_thread_start(thi);
@@ -1905,7 +470,6 @@ void _drbd_thread_stop(struct drbd_thread *thi, int restart, int wait)
                init_completion(&thi->stop);
                if (thi->task != current)
                        force_sig(DRBD_SIGKILL, thi->task);
-
        }
 
        spin_unlock_irqrestore(&thi->t_lock, flags);
@@ -1914,6 +478,35 @@ void _drbd_thread_stop(struct drbd_thread *thi, int restart, int wait)
                wait_for_completion(&thi->stop);
 }
 
+static struct drbd_thread *drbd_task_to_thread(struct drbd_tconn *tconn, struct task_struct *task)
+{
+       struct drbd_thread *thi =
+               task == tconn->receiver.task ? &tconn->receiver :
+               task == tconn->asender.task  ? &tconn->asender :
+               task == tconn->worker.task   ? &tconn->worker : NULL;
+
+       return thi;
+}
+
+char *drbd_task_to_thread_name(struct drbd_tconn *tconn, struct task_struct *task)
+{
+       struct drbd_thread *thi = drbd_task_to_thread(tconn, task);
+       return thi ? thi->name : task->comm;
+}
+
+int conn_lowest_minor(struct drbd_tconn *tconn)
+{
+       struct drbd_conf *mdev;
+       int vnr = 0, m;
+
+       rcu_read_lock();
+       mdev = idr_get_next(&tconn->volumes, &vnr);
+       m = mdev ? mdev_to_minor(mdev) : -1;
+       rcu_read_unlock();
+
+       return m;
+}
+
 #ifdef CONFIG_SMP
 /**
  * drbd_calc_cpu_mask() - Generate CPU masks, spread over all CPUs
@@ -1922,240 +515,345 @@ void _drbd_thread_stop(struct drbd_thread *thi, int restart, int wait)
  * Forces all threads of a device onto the same CPU. This is beneficial for
  * DRBD's performance. May be overwritten by user's configuration.
  */
-void drbd_calc_cpu_mask(struct drbd_conf *mdev)
+void drbd_calc_cpu_mask(struct drbd_tconn *tconn)
 {
        int ord, cpu;
 
        /* user override. */
-       if (cpumask_weight(mdev->cpu_mask))
+       if (cpumask_weight(tconn->cpu_mask))
                return;
 
-       ord = mdev_to_minor(mdev) % cpumask_weight(cpu_online_mask);
+       ord = conn_lowest_minor(tconn) % cpumask_weight(cpu_online_mask);
        for_each_online_cpu(cpu) {
                if (ord-- == 0) {
-                       cpumask_set_cpu(cpu, mdev->cpu_mask);
+                       cpumask_set_cpu(cpu, tconn->cpu_mask);
                        return;
                }
        }
        /* should not be reached */
-       cpumask_setall(mdev->cpu_mask);
+       cpumask_setall(tconn->cpu_mask);
 }
 
 /**
  * drbd_thread_current_set_cpu() - modifies the cpu mask of the _current_ thread
  * @mdev:      DRBD device.
+ * @thi:       drbd_thread object
  *
  * call in the "main loop" of _all_ threads, no need for any mutex, current won't die
  * prematurely.
  */
-void drbd_thread_current_set_cpu(struct drbd_conf *mdev)
+void drbd_thread_current_set_cpu(struct drbd_thread *thi)
 {
        struct task_struct *p = current;
-       struct drbd_thread *thi =
-               p == mdev->asender.task  ? &mdev->asender  :
-               p == mdev->receiver.task ? &mdev->receiver :
-               p == mdev->worker.task   ? &mdev->worker   :
-               NULL;
-       ERR_IF(thi == NULL)
-               return;
+
        if (!thi->reset_cpu_mask)
                return;
        thi->reset_cpu_mask = 0;
-       set_cpus_allowed_ptr(p, mdev->cpu_mask);
+       set_cpus_allowed_ptr(p, thi->tconn->cpu_mask);
 }
 #endif
 
-/* the appropriate socket mutex must be held already */
-int _drbd_send_cmd(struct drbd_conf *mdev, struct socket *sock,
-                         enum drbd_packets cmd, struct p_header80 *h,
-                         size_t size, unsigned msg_flags)
+/**
+ * drbd_header_size  -  size of a packet header
+ *
+ * The header size is a multiple of 8, so any payload following the header is
+ * word aligned on 64-bit architectures.  (The bitmap send and receive code
+ * relies on this.)
+ */
+unsigned int drbd_header_size(struct drbd_tconn *tconn)
 {
-       int sent, ok;
+       if (tconn->agreed_pro_version >= 100) {
+               BUILD_BUG_ON(!IS_ALIGNED(sizeof(struct p_header100), 8));
+               return sizeof(struct p_header100);
+       } else {
+               BUILD_BUG_ON(sizeof(struct p_header80) !=
+                            sizeof(struct p_header95));
+               BUILD_BUG_ON(!IS_ALIGNED(sizeof(struct p_header80), 8));
+               return sizeof(struct p_header80);
+       }
+}
 
-       ERR_IF(!h) return false;
-       ERR_IF(!size) return false;
+static unsigned int prepare_header80(struct p_header80 *h, enum drbd_packet cmd, int size)
+{
+       h->magic   = cpu_to_be32(DRBD_MAGIC);
+       h->command = cpu_to_be16(cmd);
+       h->length  = cpu_to_be16(size);
+       return sizeof(struct p_header80);
+}
 
-       h->magic   = BE_DRBD_MAGIC;
+static unsigned int prepare_header95(struct p_header95 *h, enum drbd_packet cmd, int size)
+{
+       h->magic   = cpu_to_be16(DRBD_MAGIC_BIG);
        h->command = cpu_to_be16(cmd);
-       h->length  = cpu_to_be16(size-sizeof(struct p_header80));
+       h->length = cpu_to_be32(size);
+       return sizeof(struct p_header95);
+}
 
-       sent = drbd_send(mdev, sock, h, size, msg_flags);
+static unsigned int prepare_header100(struct p_header100 *h, enum drbd_packet cmd,
+                                     int size, int vnr)
+{
+       h->magic = cpu_to_be32(DRBD_MAGIC_100);
+       h->volume = cpu_to_be16(vnr);
+       h->command = cpu_to_be16(cmd);
+       h->length = cpu_to_be32(size);
+       h->pad = 0;
+       return sizeof(struct p_header100);
+}
 
-       ok = (sent == size);
-       if (!ok && !signal_pending(current))
-               dev_warn(DEV, "short sent %s size=%d sent=%d\n",
-                   cmdname(cmd), (int)size, sent);
-       return ok;
+static unsigned int prepare_header(struct drbd_tconn *tconn, int vnr,
+                                  void *buffer, enum drbd_packet cmd, int size)
+{
+       if (tconn->agreed_pro_version >= 100)
+               return prepare_header100(buffer, cmd, size, vnr);
+       else if (tconn->agreed_pro_version >= 95 &&
+                size > DRBD_MAX_SIZE_H80_PACKET)
+               return prepare_header95(buffer, cmd, size);
+       else
+               return prepare_header80(buffer, cmd, size);
 }
 
-/* don't pass the socket. we may only look at it
- * when we hold the appropriate socket mutex.
- */
-int drbd_send_cmd(struct drbd_conf *mdev, int use_data_socket,
-                 enum drbd_packets cmd, struct p_header80 *h, size_t size)
+static void *__conn_prepare_command(struct drbd_tconn *tconn,
+                                   struct drbd_socket *sock)
 {
-       int ok = 0;
-       struct socket *sock;
+       if (!sock->socket)
+               return NULL;
+       return sock->sbuf + drbd_header_size(tconn);
+}
 
-       if (use_data_socket) {
-               mutex_lock(&mdev->data.mutex);
-               sock = mdev->data.socket;
-       } else {
-               mutex_lock(&mdev->meta.mutex);
-               sock = mdev->meta.socket;
-       }
+void *conn_prepare_command(struct drbd_tconn *tconn, struct drbd_socket *sock)
+{
+       void *p;
 
-       /* drbd_disconnect() could have called drbd_free_sock()
-        * while we were waiting in down()... */
-       if (likely(sock != NULL))
-               ok = _drbd_send_cmd(mdev, sock, cmd, h, size, 0);
+       mutex_lock(&sock->mutex);
+       p = __conn_prepare_command(tconn, sock);
+       if (!p)
+               mutex_unlock(&sock->mutex);
 
-       if (use_data_socket)
-               mutex_unlock(&mdev->data.mutex);
-       else
-               mutex_unlock(&mdev->meta.mutex);
-       return ok;
+       return p;
 }
 
-int drbd_send_cmd2(struct drbd_conf *mdev, enum drbd_packets cmd, char *data,
-                  size_t size)
+void *drbd_prepare_command(struct drbd_conf *mdev, struct drbd_socket *sock)
 {
-       struct p_header80 h;
-       int ok;
+       return conn_prepare_command(mdev->tconn, sock);
+}
 
-       h.magic   = BE_DRBD_MAGIC;
-       h.command = cpu_to_be16(cmd);
-       h.length  = cpu_to_be16(size);
+static int __send_command(struct drbd_tconn *tconn, int vnr,
+                         struct drbd_socket *sock, enum drbd_packet cmd,
+                         unsigned int header_size, void *data,
+                         unsigned int size)
+{
+       int msg_flags;
+       int err;
 
-       if (!drbd_get_data_sock(mdev))
-               return 0;
+       /*
+        * Called with @data == NULL and the size of the data blocks in @size
+        * for commands that send data blocks.  For those commands, omit the
+        * MSG_MORE flag: this will increase the likelihood that data blocks
+        * which are page aligned on the sender will end up page aligned on the
+        * receiver.
+        */
+       msg_flags = data ? MSG_MORE : 0;
+
+       header_size += prepare_header(tconn, vnr, sock->sbuf, cmd,
+                                     header_size + size);
+       err = drbd_send_all(tconn, sock->socket, sock->sbuf, header_size,
+                           msg_flags);
+       if (data && !err)
+               err = drbd_send_all(tconn, sock->socket, data, size, 0);
+       return err;
+}
+
+static int __conn_send_command(struct drbd_tconn *tconn, struct drbd_socket *sock,
+                              enum drbd_packet cmd, unsigned int header_size,
+                              void *data, unsigned int size)
+{
+       return __send_command(tconn, 0, sock, cmd, header_size, data, size);
+}
+
+int conn_send_command(struct drbd_tconn *tconn, struct drbd_socket *sock,
+                     enum drbd_packet cmd, unsigned int header_size,
+                     void *data, unsigned int size)
+{
+       int err;
+
+       err = __conn_send_command(tconn, sock, cmd, header_size, data, size);
+       mutex_unlock(&sock->mutex);
+       return err;
+}
+
+int drbd_send_command(struct drbd_conf *mdev, struct drbd_socket *sock,
+                     enum drbd_packet cmd, unsigned int header_size,
+                     void *data, unsigned int size)
+{
+       int err;
+
+       err = __send_command(mdev->tconn, mdev->vnr, sock, cmd, header_size,
+                            data, size);
+       mutex_unlock(&sock->mutex);
+       return err;
+}
 
-       ok = (sizeof(h) ==
-               drbd_send(mdev, mdev->data.socket, &h, sizeof(h), 0));
-       ok = ok && (size ==
-               drbd_send(mdev, mdev->data.socket, data, size, 0));
+int drbd_send_ping(struct drbd_tconn *tconn)
+{
+       struct drbd_socket *sock;
+
+       sock = &tconn->meta;
+       if (!conn_prepare_command(tconn, sock))
+               return -EIO;
+       return conn_send_command(tconn, sock, P_PING, 0, NULL, 0);
+}
 
-       drbd_put_data_sock(mdev);
+int drbd_send_ping_ack(struct drbd_tconn *tconn)
+{
+       struct drbd_socket *sock;
 
-       return ok;
+       sock = &tconn->meta;
+       if (!conn_prepare_command(tconn, sock))
+               return -EIO;
+       return conn_send_command(tconn, sock, P_PING_ACK, 0, NULL, 0);
 }
 
-int drbd_send_sync_param(struct drbd_conf *mdev, struct syncer_conf *sc)
+int drbd_send_sync_param(struct drbd_conf *mdev)
 {
+       struct drbd_socket *sock;
        struct p_rs_param_95 *p;
-       struct socket *sock;
-       int size, rv;
-       const int apv = mdev->agreed_pro_version;
+       int size;
+       const int apv = mdev->tconn->agreed_pro_version;
+       enum drbd_packet cmd;
+       struct net_conf *nc;
+       struct disk_conf *dc;
+
+       sock = &mdev->tconn->data;
+       p = drbd_prepare_command(mdev, sock);
+       if (!p)
+               return -EIO;
+
+       rcu_read_lock();
+       nc = rcu_dereference(mdev->tconn->net_conf);
 
        size = apv <= 87 ? sizeof(struct p_rs_param)
                : apv == 88 ? sizeof(struct p_rs_param)
-                       + strlen(mdev->sync_conf.verify_alg) + 1
+                       + strlen(nc->verify_alg) + 1
                : apv <= 94 ? sizeof(struct p_rs_param_89)
                : /* apv >= 95 */ sizeof(struct p_rs_param_95);
 
-       /* used from admin command context and receiver/worker context.
-        * to avoid kmalloc, grab the socket right here,
-        * then use the pre-allocated sbuf there */
-       mutex_lock(&mdev->data.mutex);
-       sock = mdev->data.socket;
+       cmd = apv >= 89 ? P_SYNC_PARAM89 : P_SYNC_PARAM;
 
-       if (likely(sock != NULL)) {
-               enum drbd_packets cmd = apv >= 89 ? P_SYNC_PARAM89 : P_SYNC_PARAM;
+       /* initialize verify_alg and csums_alg */
+       memset(p->verify_alg, 0, 2 * SHARED_SECRET_MAX);
 
-               p = &mdev->data.sbuf.rs_param_95;
-
-               /* initialize verify_alg and csums_alg */
-               memset(p->verify_alg, 0, 2 * SHARED_SECRET_MAX);
-
-               p->rate = cpu_to_be32(sc->rate);
-               p->c_plan_ahead = cpu_to_be32(sc->c_plan_ahead);
-               p->c_delay_target = cpu_to_be32(sc->c_delay_target);
-               p->c_fill_target = cpu_to_be32(sc->c_fill_target);
-               p->c_max_rate = cpu_to_be32(sc->c_max_rate);
-
-               if (apv >= 88)
-                       strcpy(p->verify_alg, mdev->sync_conf.verify_alg);
-               if (apv >= 89)
-                       strcpy(p->csums_alg, mdev->sync_conf.csums_alg);
-
-               rv = _drbd_send_cmd(mdev, sock, cmd, &p->head, size, 0);
-       } else
-               rv = 0; /* not ok */
+       if (get_ldev(mdev)) {
+               dc = rcu_dereference(mdev->ldev->disk_conf);
+               p->resync_rate = cpu_to_be32(dc->resync_rate);
+               p->c_plan_ahead = cpu_to_be32(dc->c_plan_ahead);
+               p->c_delay_target = cpu_to_be32(dc->c_delay_target);
+               p->c_fill_target = cpu_to_be32(dc->c_fill_target);
+               p->c_max_rate = cpu_to_be32(dc->c_max_rate);
+               put_ldev(mdev);
+       } else {
+               p->resync_rate = cpu_to_be32(DRBD_RESYNC_RATE_DEF);
+               p->c_plan_ahead = cpu_to_be32(DRBD_C_PLAN_AHEAD_DEF);
+               p->c_delay_target = cpu_to_be32(DRBD_C_DELAY_TARGET_DEF);
+               p->c_fill_target = cpu_to_be32(DRBD_C_FILL_TARGET_DEF);
+               p->c_max_rate = cpu_to_be32(DRBD_C_MAX_RATE_DEF);
+       }
 
-       mutex_unlock(&mdev->data.mutex);
+       if (apv >= 88)
+               strcpy(p->verify_alg, nc->verify_alg);
+       if (apv >= 89)
+               strcpy(p->csums_alg, nc->csums_alg);
+       rcu_read_unlock();
 
-       return rv;
+       return drbd_send_command(mdev, sock, cmd, size, NULL, 0);
 }
 
-int drbd_send_protocol(struct drbd_conf *mdev)
+int __drbd_send_protocol(struct drbd_tconn *tconn, enum drbd_packet cmd)
 {
+       struct drbd_socket *sock;
        struct p_protocol *p;
-       int size, cf, rv;
+       struct net_conf *nc;
+       int size, cf;
 
-       size = sizeof(struct p_protocol);
+       sock = &tconn->data;
+       p = __conn_prepare_command(tconn, sock);
+       if (!p)
+               return -EIO;
 
-       if (mdev->agreed_pro_version >= 87)
-               size += strlen(mdev->net_conf->integrity_alg) + 1;
+       rcu_read_lock();
+       nc = rcu_dereference(tconn->net_conf);
 
-       /* we must not recurse into our own queue,
-        * as that is blocked during handshake */
-       p = kmalloc(size, GFP_NOIO);
-       if (p == NULL)
-               return 0;
+       if (nc->tentative && tconn->agreed_pro_version < 92) {
+               rcu_read_unlock();
+               mutex_unlock(&sock->mutex);
+               conn_err(tconn, "--dry-run is not supported by peer");
+               return -EOPNOTSUPP;
+       }
 
-       p->protocol      = cpu_to_be32(mdev->net_conf->wire_protocol);
-       p->after_sb_0p   = cpu_to_be32(mdev->net_conf->after_sb_0p);
-       p->after_sb_1p   = cpu_to_be32(mdev->net_conf->after_sb_1p);
-       p->after_sb_2p   = cpu_to_be32(mdev->net_conf->after_sb_2p);
-       p->two_primaries = cpu_to_be32(mdev->net_conf->two_primaries);
+       size = sizeof(*p);
+       if (tconn->agreed_pro_version >= 87)
+               size += strlen(nc->integrity_alg) + 1;
 
+       p->protocol      = cpu_to_be32(nc->wire_protocol);
+       p->after_sb_0p   = cpu_to_be32(nc->after_sb_0p);
+       p->after_sb_1p   = cpu_to_be32(nc->after_sb_1p);
+       p->after_sb_2p   = cpu_to_be32(nc->after_sb_2p);
+       p->two_primaries = cpu_to_be32(nc->two_primaries);
        cf = 0;
-       if (mdev->net_conf->want_lose)
-               cf |= CF_WANT_LOSE;
-       if (mdev->net_conf->dry_run) {
-               if (mdev->agreed_pro_version >= 92)
-                       cf |= CF_DRY_RUN;
-               else {
-                       dev_err(DEV, "--dry-run is not supported by peer");
-                       kfree(p);
-                       return -1;
-               }
-       }
+       if (nc->discard_my_data)
+               cf |= CF_DISCARD_MY_DATA;
+       if (nc->tentative)
+               cf |= CF_DRY_RUN;
        p->conn_flags    = cpu_to_be32(cf);
 
-       if (mdev->agreed_pro_version >= 87)
-               strcpy(p->integrity_alg, mdev->net_conf->integrity_alg);
+       if (tconn->agreed_pro_version >= 87)
+               strcpy(p->integrity_alg, nc->integrity_alg);
+       rcu_read_unlock();
 
-       rv = drbd_send_cmd(mdev, USE_DATA_SOCKET, P_PROTOCOL,
-                          (struct p_header80 *)p, size);
-       kfree(p);
-       return rv;
+       return __conn_send_command(tconn, sock, cmd, size, NULL, 0);
+}
+
+int drbd_send_protocol(struct drbd_tconn *tconn)
+{
+       int err;
+
+       mutex_lock(&tconn->data.mutex);
+       err = __drbd_send_protocol(tconn, P_PROTOCOL);
+       mutex_unlock(&tconn->data.mutex);
+
+       return err;
 }
 
 int _drbd_send_uuids(struct drbd_conf *mdev, u64 uuid_flags)
 {
-       struct p_uuids p;
+       struct drbd_socket *sock;
+       struct p_uuids *p;
        int i;
 
        if (!get_ldev_if_state(mdev, D_NEGOTIATING))
-               return 1;
+               return 0;
 
+       sock = &mdev->tconn->data;
+       p = drbd_prepare_command(mdev, sock);
+       if (!p) {
+               put_ldev(mdev);
+               return -EIO;
+       }
        spin_lock_irq(&mdev->ldev->md.uuid_lock);
        for (i = UI_CURRENT; i < UI_SIZE; i++)
-               p.uuid[i] = mdev->ldev ? cpu_to_be64(mdev->ldev->md.uuid[i]) : 0;
+               p->uuid[i] = mdev->ldev ? cpu_to_be64(mdev->ldev->md.uuid[i]) : 0;
        spin_unlock_irq(&mdev->ldev->md.uuid_lock);
 
        mdev->comm_bm_set = drbd_bm_total_weight(mdev);
-       p.uuid[UI_SIZE] = cpu_to_be64(mdev->comm_bm_set);
-       uuid_flags |= mdev->net_conf->want_lose ? 1 : 0;
-       uuid_flags |= drbd_test_flag(mdev, CRASHED_PRIMARY) ? 2 : 0;
+       p->uuid[UI_SIZE] = cpu_to_be64(mdev->comm_bm_set);
+       rcu_read_lock();
+       uuid_flags |= rcu_dereference(mdev->tconn->net_conf)->discard_my_data ? 1 : 0;
+       rcu_read_unlock();
+       uuid_flags |= test_bit(CRASHED_PRIMARY, &mdev->flags) ? 2 : 0;
        uuid_flags |= mdev->new_state_tmp.disk == D_INCONSISTENT ? 4 : 0;
-       p.uuid[UI_FLAGS] = cpu_to_be64(uuid_flags);
+       p->uuid[UI_FLAGS] = cpu_to_be64(uuid_flags);
 
        put_ldev(mdev);
-
-       return drbd_send_cmd(mdev, USE_DATA_SOCKET, P_UUIDS,
-                            (struct p_header80 *)&p, sizeof(p));
+       return drbd_send_command(mdev, sock, P_UUIDS, sizeof(*p), NULL, 0);
 }
 
 int drbd_send_uuids(struct drbd_conf *mdev)
@@ -2186,9 +884,10 @@ void drbd_print_uuids(struct drbd_conf *mdev, const char *text)
        }
 }
 
-int drbd_gen_and_send_sync_uuid(struct drbd_conf *mdev)
+void drbd_gen_and_send_sync_uuid(struct drbd_conf *mdev)
 {
-       struct p_rs_uuid p;
+       struct drbd_socket *sock;
+       struct p_rs_uuid *p;
        u64 uuid;
 
        D_ASSERT(mdev->state.disk == D_UP_TO_DATE);
@@ -2201,24 +900,29 @@ int drbd_gen_and_send_sync_uuid(struct drbd_conf *mdev)
        drbd_uuid_set(mdev, UI_BITMAP, uuid);
        drbd_print_uuids(mdev, "updated sync UUID");
        drbd_md_sync(mdev);
-       p.uuid = cpu_to_be64(uuid);
 
-       return drbd_send_cmd(mdev, USE_DATA_SOCKET, P_SYNC_UUID,
-                            (struct p_header80 *)&p, sizeof(p));
+       sock = &mdev->tconn->data;
+       p = drbd_prepare_command(mdev, sock);
+       if (p) {
+               p->uuid = cpu_to_be64(uuid);
+               drbd_send_command(mdev, sock, P_SYNC_UUID, sizeof(*p), NULL, 0);
+       }
 }
 
 int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags flags)
 {
-       struct p_sizes p;
+       struct drbd_socket *sock;
+       struct p_sizes *p;
        sector_t d_size, u_size;
        int q_order_type;
        unsigned int max_bio_size;
-       int ok;
 
        if (get_ldev_if_state(mdev, D_NEGOTIATING)) {
                D_ASSERT(mdev->ldev->backing_bdev);
                d_size = drbd_get_max_capacity(mdev->ldev);
-               u_size = mdev->ldev->dc.disk_size;
+               rcu_read_lock();
+               u_size = rcu_dereference(mdev->ldev->disk_conf)->disk_size;
+               rcu_read_unlock();
                q_order_type = drbd_queue_order_type(mdev);
                max_bio_size = queue_max_hw_sectors(mdev->ldev->backing_bdev->bd_disk->queue) << 9;
                max_bio_size = min(max_bio_size, DRBD_MAX_BIO_SIZE);
@@ -2230,20 +934,23 @@ int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags fl
                max_bio_size = DRBD_MAX_BIO_SIZE; /* ... multiple BIOs per peer_request */
        }
 
-       /* Never allow old drbd (up to 8.3.7) to see more than 32KiB */
-       if (mdev->agreed_pro_version <= 94)
-               max_bio_size = min(max_bio_size, DRBD_MAX_SIZE_H80_PACKET);
+       sock = &mdev->tconn->data;
+       p = drbd_prepare_command(mdev, sock);
+       if (!p)
+               return -EIO;
 
-       p.d_size = cpu_to_be64(d_size);
-       p.u_size = cpu_to_be64(u_size);
-       p.c_size = cpu_to_be64(trigger_reply ? 0 : drbd_get_capacity(mdev->this_bdev));
-       p.max_bio_size = cpu_to_be32(max_bio_size);
-       p.queue_order_type = cpu_to_be16(q_order_type);
-       p.dds_flags = cpu_to_be16(flags);
+       if (mdev->tconn->agreed_pro_version <= 94)
+               max_bio_size = min(max_bio_size, DRBD_MAX_SIZE_H80_PACKET);
+       else if (mdev->tconn->agreed_pro_version < 100)
+               max_bio_size = min(max_bio_size, DRBD_MAX_BIO_SIZE_P95);
 
-       ok = drbd_send_cmd(mdev, USE_DATA_SOCKET, P_SIZES,
-                          (struct p_header80 *)&p, sizeof(p));
-       return ok;
+       p->d_size = cpu_to_be64(d_size);
+       p->u_size = cpu_to_be64(u_size);
+       p->c_size = cpu_to_be64(trigger_reply ? 0 : drbd_get_capacity(mdev->this_bdev));
+       p->max_bio_size = cpu_to_be32(max_bio_size);
+       p->queue_order_type = cpu_to_be16(q_order_type);
+       p->dds_flags = cpu_to_be16(flags);
+       return drbd_send_command(mdev, sock, P_SIZES, sizeof(*p), NULL, 0);
 }
 
 /**
@@ -2252,34 +959,21 @@ int drbd_send_sizes(struct drbd_conf *mdev, int trigger_reply, enum dds_flags fl
  */
 int drbd_send_current_state(struct drbd_conf *mdev)
 {
-       struct socket *sock;
-       struct p_state p;
-       int ok = 0;
-
-       /* Grab state lock so we wont send state if we're in the middle
-        * of a cluster wide state change on another thread */
-       drbd_state_lock(mdev);
-
-       mutex_lock(&mdev->data.mutex);
-
-       p.state = cpu_to_be32(mdev->state.i); /* Within the send mutex */
-       sock = mdev->data.socket;
+       struct drbd_socket *sock;
+       struct p_state *p;
 
-       if (likely(sock != NULL)) {
-               ok = _drbd_send_cmd(mdev, sock, P_STATE,
-                                   (struct p_header80 *)&p, sizeof(p), 0);
-       }
-
-       mutex_unlock(&mdev->data.mutex);
-
-       drbd_state_unlock(mdev);
-       return ok;
+       sock = &mdev->tconn->data;
+       p = drbd_prepare_command(mdev, sock);
+       if (!p)
+               return -EIO;
+       p->state = cpu_to_be32(mdev->state.i); /* Within the send mutex */
+       return drbd_send_command(mdev, sock, P_STATE, sizeof(*p), NULL, 0);
 }
 
 /**
  * drbd_send_state() - After a state change, sends the new state to the peer
- * @mdev:      DRBD device.
- * @state:     the state to send, not necessarily the current state.
+ * @mdev:      DRBD device.
+ * @state:     the state to send, not necessarily the current state.
  *
  * Each state change queues an "after_state_ch" work, which will eventually
  * send the resulting new state to the peer. If more state changes happen
@@ -2288,50 +982,95 @@ int drbd_send_current_state(struct drbd_conf *mdev)
  */
 int drbd_send_state(struct drbd_conf *mdev, union drbd_state state)
 {
-       struct socket *sock;
-       struct p_state p;
-       int ok = 0;
+       struct drbd_socket *sock;
+       struct p_state *p;
 
-       mutex_lock(&mdev->data.mutex);
+       sock = &mdev->tconn->data;
+       p = drbd_prepare_command(mdev, sock);
+       if (!p)
+               return -EIO;
+       p->state = cpu_to_be32(state.i); /* Within the send mutex */
+       return drbd_send_command(mdev, sock, P_STATE, sizeof(*p), NULL, 0);
+}
 
-       p.state = cpu_to_be32(state.i);
-       sock = mdev->data.socket;
+int drbd_send_state_req(struct drbd_conf *mdev, union drbd_state mask, union drbd_state val)
+{
+       struct drbd_socket *sock;
+       struct p_req_state *p;
 
-       if (likely(sock != NULL)) {
-               ok = _drbd_send_cmd(mdev, sock, P_STATE,
-                                   (struct p_header80 *)&p, sizeof(p), 0);
-       }
+       sock = &mdev->tconn->data;
+       p = drbd_prepare_command(mdev, sock);
+       if (!p)
+               return -EIO;
+       p->mask = cpu_to_be32(mask.i);
+       p->val = cpu_to_be32(val.i);
+       return drbd_send_command(mdev, sock, P_STATE_CHG_REQ, sizeof(*p), NULL, 0);
+}
 
-       mutex_unlock(&mdev->data.mutex);
+int conn_send_state_req(struct drbd_tconn *tconn, union drbd_state mask, union drbd_state val)
+{
+       enum drbd_packet cmd;
+       struct drbd_socket *sock;
+       struct p_req_state *p;
 
-       return ok;
+       cmd = tconn->agreed_pro_version < 100 ? P_STATE_CHG_REQ : P_CONN_ST_CHG_REQ;
+       sock = &tconn->data;
+       p = conn_prepare_command(tconn, sock);
+       if (!p)
+               return -EIO;
+       p->mask = cpu_to_be32(mask.i);
+       p->val = cpu_to_be32(val.i);
+       return conn_send_command(tconn, sock, cmd, sizeof(*p), NULL, 0);
 }
 
-int drbd_send_state_req(struct drbd_conf *mdev,
-       union drbd_state mask, union drbd_state val)
+void drbd_send_sr_reply(struct drbd_conf *mdev, enum drbd_state_rv retcode)
 {
-       struct p_req_state p;
+       struct drbd_socket *sock;
+       struct p_req_state_reply *p;
+
+       sock = &mdev->tconn->meta;
+       p = drbd_prepare_command(mdev, sock);
+       if (p) {
+               p->retcode = cpu_to_be32(retcode);
+               drbd_send_command(mdev, sock, P_STATE_CHG_REPLY, sizeof(*p), NULL, 0);
+       }
+}
 
-       p.mask    = cpu_to_be32(mask.i);
-       p.val     = cpu_to_be32(val.i);
+void conn_send_sr_reply(struct drbd_tconn *tconn, enum drbd_state_rv retcode)
+{
+       struct drbd_socket *sock;
+       struct p_req_state_reply *p;
+       enum drbd_packet cmd = tconn->agreed_pro_version < 100 ? P_STATE_CHG_REPLY : P_CONN_ST_CHG_REPLY;
 
-       return drbd_send_cmd(mdev, USE_DATA_SOCKET, P_STATE_CHG_REQ,
-                            (struct p_header80 *)&p, sizeof(p));
+       sock = &tconn->meta;
+       p = conn_prepare_command(tconn, sock);
+       if (p) {
+               p->retcode = cpu_to_be32(retcode);
+               conn_send_command(tconn, sock, cmd, sizeof(*p), NULL, 0);
+       }
 }
 
-int drbd_send_sr_reply(struct drbd_conf *mdev, enum drbd_state_rv retcode)
+static void dcbp_set_code(struct p_compressed_bm *p, enum drbd_bitmap_code code)
 {
-       struct p_req_state_reply p;
+       BUG_ON(code & ~0xf);
+       p->encoding = (p->encoding & ~0xf) | code;
+}
 
-       p.retcode    = cpu_to_be32(retcode);
+static void dcbp_set_start(struct p_compressed_bm *p, int set)
+{
+       p->encoding = (p->encoding & ~0x80) | (set ? 0x80 : 0);
+}
 
-       return drbd_send_cmd(mdev, USE_META_SOCKET, P_STATE_CHG_REPLY,
-                            (struct p_header80 *)&p, sizeof(p));
+static void dcbp_set_pad_bits(struct p_compressed_bm *p, int n)
+{
+       BUG_ON(n & ~0x7);
+       p->encoding = (p->encoding & (~0x7 << 4)) | (n << 4);
 }
 
 int fill_bitmap_rle_bits(struct drbd_conf *mdev,
-       struct p_compressed_bm *p,
-       struct bm_xfer_ctx *c)
+                        struct p_compressed_bm *p,
+                        unsigned int size,
+                        struct bm_xfer_ctx *c)
 {
        struct bitstream bs;
        unsigned long plain_bits;
@@ -2339,19 +1078,21 @@ int fill_bitmap_rle_bits(struct drbd_conf *mdev,
        unsigned long rl;
        unsigned len;
        unsigned toggle;
-       int bits;
+       int bits, use_rle;
 
        /* may we use this feature? */
-       if ((mdev->sync_conf.use_rle == 0) ||
-               (mdev->agreed_pro_version < 90))
-                       return 0;
+       rcu_read_lock();
+       use_rle = rcu_dereference(mdev->tconn->net_conf)->use_rle;
+       rcu_read_unlock();
+       if (!use_rle || mdev->tconn->agreed_pro_version < 90)
+               return 0;
 
        if (c->bit_offset >= c->bm_bits)
                return 0; /* nothing to do. */
 
        /* use at most thus many bytes */
-       bitstream_init(&bs, p->code, BM_PACKET_VLI_BYTES_MAX, 0);
-       memset(p->code, 0, BM_PACKET_VLI_BYTES_MAX);
+       bitstream_init(&bs, p->code, size, 0);
+       memset(p->code, 0, size);
        /* plain bits covered in this code string */
        plain_bits = 0;
 
@@ -2373,12 +1114,12 @@ int fill_bitmap_rle_bits(struct drbd_conf *mdev,
                        if (rl == 0) {
                                /* the first checked bit was set,
                                 * store start value, */
-                               DCBP_set_start(p, 1);
+                               dcbp_set_start(p, 1);
                                /* but skip encoding of zero run length */
                                toggle = !toggle;
                                continue;
                        }
-                       DCBP_set_start(p, 0);
+                       dcbp_set_start(p, 0);
                }
 
                /* paranoia: catch zero runlength.
@@ -2418,7 +1159,7 @@ int fill_bitmap_rle_bits(struct drbd_conf *mdev,
        bm_xfer_ctx_bit_to_word_offset(c);
 
        /* store pad_bits */
-       DCBP_set_pad_bits(p, (8 - bs.cur.bit) & 0x7);
+       dcbp_set_pad_bits(p, (8 - bs.cur.bit) & 0x7);
 
        return len;
 }
@@ -2430,48 +1171,52 @@ int fill_bitmap_rle_bits(struct drbd_conf *mdev,
  * code upon failure.
  */
 static int
-send_bitmap_rle_or_plain(struct drbd_conf *mdev,
-                        struct p_header80 *h, struct bm_xfer_ctx *c)
+send_bitmap_rle_or_plain(struct drbd_conf *mdev, struct bm_xfer_ctx *c)
 {
-       struct p_compressed_bm *p = (void*)h;
-       unsigned long num_words;
-       int len;
-       int ok;
-
-       len = fill_bitmap_rle_bits(mdev, p, c);
+       struct drbd_socket *sock = &mdev->tconn->data;
+       unsigned int header_size = drbd_header_size(mdev->tconn);
+       struct p_compressed_bm *p = sock->sbuf + header_size;
+       int len, err;
 
+       len = fill_bitmap_rle_bits(mdev, p,
+                       DRBD_SOCKET_BUFFER_SIZE - header_size - sizeof(*p), c);
        if (len < 0)
                return -EIO;
 
        if (len) {
-               DCBP_set_code(p, RLE_VLI_Bits);
-               ok = _drbd_send_cmd(mdev, mdev->data.socket, P_COMPRESSED_BITMAP, h,
-                       sizeof(*p) + len, 0);
-
+               dcbp_set_code(p, RLE_VLI_Bits);
+               err = __send_command(mdev->tconn, mdev->vnr, sock,
+                                    P_COMPRESSED_BITMAP, sizeof(*p) + len,
+                                    NULL, 0);
                c->packets[0]++;
-               c->bytes[0] += sizeof(*p) + len;
+               c->bytes[0] += header_size + sizeof(*p) + len;
 
                if (c->bit_offset >= c->bm_bits)
                        len = 0; /* DONE */
        } else {
                /* was not compressible.
                 * send a buffer full of plain text bits instead. */
-               num_words = min_t(size_t, BM_PACKET_WORDS, c->bm_words - c->word_offset);
-               len = num_words * sizeof(long);
+               unsigned int data_size;
+               unsigned long num_words;
+               unsigned long *p = sock->sbuf + header_size;
+
+               data_size = DRBD_SOCKET_BUFFER_SIZE - header_size;
+               num_words = min_t(size_t, data_size / sizeof(*p),
+                                 c->bm_words - c->word_offset);
+               len = num_words * sizeof(*p);
                if (len)
-                       drbd_bm_get_lel(mdev, c->word_offset, num_words, (unsigned long*)h->payload);
-               ok = _drbd_send_cmd(mdev, mdev->data.socket, P_BITMAP,
-                                  h, sizeof(struct p_header80) + len, 0);
+                       drbd_bm_get_lel(mdev, c->word_offset, num_words, p);
+               err = __send_command(mdev->tconn, mdev->vnr, sock, P_BITMAP, len, NULL, 0);
                c->word_offset += num_words;
                c->bit_offset = c->word_offset * BITS_PER_LONG;
 
                c->packets[1]++;
-               c->bytes[1] += sizeof(struct p_header80) + len;
+               c->bytes[1] += header_size + len;
 
                if (c->bit_offset > c->bm_bits)
                        c->bit_offset = c->bm_bits;
        }
-       if (ok) {
+       if (!err) {
                if (len == 0) {
                        INFO_bm_xfer_stats(mdev, "send", c);
                        return 0;
@@ -2482,21 +1227,13 @@ send_bitmap_rle_or_plain(struct drbd_conf *mdev,
 }
 
 /* See the comment at receive_bitmap() */
-int _drbd_send_bitmap(struct drbd_conf *mdev)
+static int _drbd_send_bitmap(struct drbd_conf *mdev)
 {
        struct bm_xfer_ctx c;
-       struct p_header80 *p;
        int err;
 
-       ERR_IF(!mdev->bitmap) return false;
-
-       /* maybe we should use some per thread scratch page,
-        * and allocate that during initial device creation? */
-       p = (struct p_header80 *) __get_free_page(GFP_NOIO);
-       if (!p) {
-               dev_err(DEV, "failed to allocate one page buffer in %s\n", __func__);
+       if (!expect(mdev->bitmap))
                return false;
-       }
 
        if (get_ldev(mdev)) {
                if (drbd_md_test_flag(mdev->ldev, MDF_FULL_SYNC)) {
@@ -2521,37 +1258,39 @@ int _drbd_send_bitmap(struct drbd_conf *mdev)
        };
 
        do {
-               err = send_bitmap_rle_or_plain(mdev, p, &c);
+               err = send_bitmap_rle_or_plain(mdev, &c);
        } while (err > 0);
 
-       free_page((unsigned long) p);
        return err == 0;
 }
 
 int drbd_send_bitmap(struct drbd_conf *mdev)
 {
-       int err;
+       struct drbd_socket *sock = &mdev->tconn->data;
+       int err = -1;
 
-       if (!drbd_get_data_sock(mdev))
-               return -1;
-       err = !_drbd_send_bitmap(mdev);
-       drbd_put_data_sock(mdev);
+       mutex_lock(&sock->mutex);
+       if (sock->socket)
+               err = !_drbd_send_bitmap(mdev);
+       mutex_unlock(&sock->mutex);
        return err;
 }
 
-int drbd_send_b_ack(struct drbd_conf *mdev, u32 barrier_nr, u32 set_size)
+void drbd_send_b_ack(struct drbd_tconn *tconn, u32 barrier_nr, u32 set_size)
 {
-       int ok;
-       struct p_barrier_ack p;
+       struct drbd_socket *sock;
+       struct p_barrier_ack *p;
 
-       p.barrier  = barrier_nr;
-       p.set_size = cpu_to_be32(set_size);
+       if (tconn->cstate < C_WF_REPORT_PARAMS)
+               return;
 
-       if (mdev->state.conn < C_CONNECTED)
-               return false;
-       ok = drbd_send_cmd(mdev, USE_META_SOCKET, P_BARRIER_ACK,
-                       (struct p_header80 *)&p, sizeof(p));
-       return ok;
+       sock = &tconn->meta;
+       p = conn_prepare_command(tconn, sock);
+       if (!p)
+               return;
+       p->barrier = barrier_nr;
+       p->set_size = cpu_to_be32(set_size);
+       conn_send_command(tconn, sock, P_BARRIER_ACK, sizeof(*p), NULL, 0);
 }
 
 /**
@@ -2562,62 +1301,62 @@ int drbd_send_b_ack(struct drbd_conf *mdev, u32 barrier_nr, u32 set_size)
  * @blksize:   size in byte, needs to be in big endian byte order
  * @block_id:  Id, big endian byte order
  */
-static int _drbd_send_ack(struct drbd_conf *mdev, enum drbd_packets cmd,
-                         u64 sector,
-                         u32 blksize,
-                         u64 block_id)
+static int _drbd_send_ack(struct drbd_conf *mdev, enum drbd_packet cmd,
+                         u64 sector, u32 blksize, u64 block_id)
 {
-       int ok;
-       struct p_block_ack p;
+       struct drbd_socket *sock;
+       struct p_block_ack *p;
 
-       p.sector   = sector;
-       p.block_id = block_id;
-       p.blksize  = blksize;
-       p.seq_num  = cpu_to_be32(atomic_add_return(1, &mdev->packet_seq));
+       if (mdev->state.conn < C_CONNECTED)
+               return -EIO;
 
-       if (!mdev->meta.socket || mdev->state.conn < C_CONNECTED)
-               return false;
-       ok = drbd_send_cmd(mdev, USE_META_SOCKET, cmd,
-                               (struct p_header80 *)&p, sizeof(p));
-       return ok;
+       sock = &mdev->tconn->meta;
+       p = drbd_prepare_command(mdev, sock);
+       if (!p)
+               return -EIO;
+       p->sector = sector;
+       p->block_id = block_id;
+       p->blksize = blksize;
+       p->seq_num = cpu_to_be32(atomic_inc_return(&mdev->packet_seq));
+       return drbd_send_command(mdev, sock, cmd, sizeof(*p), NULL, 0);
 }
 
 /* dp->sector and dp->block_id already/still in network byte order,
  * data_size is payload size according to dp->head,
  * and may need to be corrected for digest size. */
-int drbd_send_ack_dp(struct drbd_conf *mdev, enum drbd_packets cmd,
-                    struct p_data *dp, int data_size)
+void drbd_send_ack_dp(struct drbd_conf *mdev, enum drbd_packet cmd,
+                     struct p_data *dp, int data_size)
 {
-       data_size -= (mdev->agreed_pro_version >= 87 && mdev->integrity_r_tfm) ?
-               crypto_hash_digestsize(mdev->integrity_r_tfm) : 0;
-       return _drbd_send_ack(mdev, cmd, dp->sector, cpu_to_be32(data_size),
-                             dp->block_id);
+       if (mdev->tconn->peer_integrity_tfm)
+               data_size -= crypto_hash_digestsize(mdev->tconn->peer_integrity_tfm);
+       _drbd_send_ack(mdev, cmd, dp->sector, cpu_to_be32(data_size),
+                      dp->block_id);
 }
 
-int drbd_send_ack_rp(struct drbd_conf *mdev, enum drbd_packets cmd,
-                    struct p_block_req *rp)
+void drbd_send_ack_rp(struct drbd_conf *mdev, enum drbd_packet cmd,
+                     struct p_block_req *rp)
 {
-       return _drbd_send_ack(mdev, cmd, rp->sector, rp->blksize, rp->block_id);
+       _drbd_send_ack(mdev, cmd, rp->sector, rp->blksize, rp->block_id);
 }
 
 /**
  * drbd_send_ack() - Sends an ack packet
- * @mdev:      DRBD device.
- * @cmd:       Packet command code.
- * @e:         Epoch entry.
+ * @mdev:      DRBD device
+ * @cmd:       packet command code
+ * @peer_req:  peer request
  */
-int drbd_send_ack(struct drbd_conf *mdev,
-       enum drbd_packets cmd, struct drbd_epoch_entry *e)
+int drbd_send_ack(struct drbd_conf *mdev, enum drbd_packet cmd,
+                 struct drbd_peer_request *peer_req)
 {
        return _drbd_send_ack(mdev, cmd,
-                             cpu_to_be64(e->sector),
-                             cpu_to_be32(e->size),
-                             e->block_id);
+                             cpu_to_be64(peer_req->i.sector),
+                             cpu_to_be32(peer_req->i.size),
+                             peer_req->block_id);
 }
 
 /* This function misuses the block_id field to signal if the blocks
  * are is sync or not. */
-int drbd_send_ack_ex(struct drbd_conf *mdev, enum drbd_packets cmd,
+int drbd_send_ack_ex(struct drbd_conf *mdev, enum drbd_packet cmd,
                     sector_t sector, int blksize, u64 block_id)
 {
        return _drbd_send_ack(mdev, cmd,
@@ -2629,85 +1368,87 @@ int drbd_send_ack_ex(struct drbd_conf *mdev, enum drbd_packets cmd,
 int drbd_send_drequest(struct drbd_conf *mdev, int cmd,
                       sector_t sector, int size, u64 block_id)
 {
-       int ok;
-       struct p_block_req p;
+       struct drbd_socket *sock;
+       struct p_block_req *p;
 
-       p.sector   = cpu_to_be64(sector);
-       p.block_id = block_id;
-       p.blksize  = cpu_to_be32(size);
-
-       ok = drbd_send_cmd(mdev, USE_DATA_SOCKET, cmd,
-                               (struct p_header80 *)&p, sizeof(p));
-       return ok;
+       sock = &mdev->tconn->data;
+       p = drbd_prepare_command(mdev, sock);
+       if (!p)
+               return -EIO;
+       p->sector = cpu_to_be64(sector);
+       p->block_id = block_id;
+       p->blksize = cpu_to_be32(size);
+       return drbd_send_command(mdev, sock, cmd, sizeof(*p), NULL, 0);
 }
 
-int drbd_send_drequest_csum(struct drbd_conf *mdev,
-                           sector_t sector, int size,
-                           void *digest, int digest_size,
-                           enum drbd_packets cmd)
+int drbd_send_drequest_csum(struct drbd_conf *mdev, sector_t sector, int size,
+                           void *digest, int digest_size, enum drbd_packet cmd)
 {
-       int ok;
-       struct p_block_req p;
-
-       p.sector   = cpu_to_be64(sector);
-       p.block_id = BE_DRBD_MAGIC + 0xbeef;
-       p.blksize  = cpu_to_be32(size);
-
-       p.head.magic   = BE_DRBD_MAGIC;
-       p.head.command = cpu_to_be16(cmd);
-       p.head.length  = cpu_to_be16(sizeof(p) - sizeof(struct p_header80) + digest_size);
+       struct drbd_socket *sock;
+       struct p_block_req *p;
 
-       mutex_lock(&mdev->data.mutex);
+       /* FIXME: Put the digest into the preallocated socket buffer.  */
 
-       ok = (sizeof(p) == drbd_send(mdev, mdev->data.socket, &p, sizeof(p), 0));
-       ok = ok && (digest_size == drbd_send(mdev, mdev->data.socket, digest, digest_size, 0));
-
-       mutex_unlock(&mdev->data.mutex);
-
-       return ok;
+       sock = &mdev->tconn->data;
+       p = drbd_prepare_command(mdev, sock);
+       if (!p)
+               return -EIO;
+       p->sector = cpu_to_be64(sector);
+       p->block_id = ID_SYNCER /* unused */;
+       p->blksize = cpu_to_be32(size);
+       return drbd_send_command(mdev, sock, cmd, sizeof(*p),
+                                digest, digest_size);
 }
 
 int drbd_send_ov_request(struct drbd_conf *mdev, sector_t sector, int size)
 {
-       int ok;
-       struct p_block_req p;
-
-       p.sector   = cpu_to_be64(sector);
-       p.block_id = BE_DRBD_MAGIC + 0xbabe;
-       p.blksize  = cpu_to_be32(size);
+       struct drbd_socket *sock;
+       struct p_block_req *p;
 
-       ok = drbd_send_cmd(mdev, USE_DATA_SOCKET, P_OV_REQUEST,
-                          (struct p_header80 *)&p, sizeof(p));
-       return ok;
+       sock = &mdev->tconn->data;
+       p = drbd_prepare_command(mdev, sock);
+       if (!p)
+               return -EIO;
+       p->sector = cpu_to_be64(sector);
+       p->block_id = ID_SYNCER /* unused */;
+       p->blksize = cpu_to_be32(size);
+       return drbd_send_command(mdev, sock, P_OV_REQUEST, sizeof(*p), NULL, 0);
 }
 
 /* called on sndtimeo
  * returns false if we should retry,
  * true if we think connection is dead
  */
-static int we_should_drop_the_connection(struct drbd_conf *mdev, struct socket *sock)
+static int we_should_drop_the_connection(struct drbd_tconn *tconn, struct socket *sock)
 {
        int drop_it;
        /* long elapsed = (long)(jiffies - mdev->last_received); */
 
-       drop_it =   mdev->meta.socket == sock
-               || !mdev->asender.task
-               || get_t_state(&mdev->asender) != Running
-               || mdev->state.conn < C_CONNECTED;
+       drop_it =   tconn->meta.socket == sock
+               || !tconn->asender.task
+               || get_t_state(&tconn->asender) != RUNNING
+               || tconn->cstate < C_WF_REPORT_PARAMS;
 
        if (drop_it)
                return true;
 
-       drop_it = !--mdev->ko_count;
+       drop_it = !--tconn->ko_count;
        if (!drop_it) {
-               dev_err(DEV, "[%s/%d] sock_sendmsg time expired, ko = %u\n",
-                      current->comm, current->pid, mdev->ko_count);
-               request_ping(mdev);
+               conn_err(tconn, "[%s/%d] sock_sendmsg time expired, ko = %u\n",
+                        current->comm, current->pid, tconn->ko_count);
+               request_ping(tconn);
        }
 
        return drop_it; /* && (mdev->state == R_PRIMARY) */;
 }
 
+static void drbd_update_congested(struct drbd_tconn *tconn)
+{
+       struct sock *sk = tconn->data.socket->sk;
+       if (sk->sk_wmem_queued > sk->sk_sndbuf * 4 / 5)
+               set_bit(NET_CONGESTED, &tconn->flags);
+}
+
 /* The idea of sendpage seems to be to put some kind of reference
  * to the page into the skb, and to hand it over to the NIC. In
  * this process get_page() gets called.
@@ -2730,21 +1471,28 @@ static int we_should_drop_the_connection(struct drbd_conf *mdev, struct socket *
  * with page_count == 0 or PageSlab.
  */
 static int _drbd_no_send_page(struct drbd_conf *mdev, struct page *page,
-                  int offset, size_t size, unsigned msg_flags)
+                             int offset, size_t size, unsigned msg_flags)
 {
-       int sent = drbd_send(mdev, mdev->data.socket, kmap(page) + offset, size, msg_flags);
+       struct socket *socket;
+       void *addr;
+       int err;
+
+       socket = mdev->tconn->data.socket;
+       addr = kmap(page) + offset;
+       err = drbd_send_all(mdev->tconn, socket, addr, size, msg_flags);
        kunmap(page);
-       if (sent == size)
-               mdev->send_cnt += size>>9;
-       return sent == size;
+       if (!err)
+               mdev->send_cnt += size >> 9;
+       return err;
 }
 
 static int _drbd_send_page(struct drbd_conf *mdev, struct page *page,
                    int offset, size_t size, unsigned msg_flags)
 {
+       struct socket *socket = mdev->tconn->data.socket;
        mm_segment_t oldfs = get_fs();
-       int sent, ok;
        int len = size;
+       int err = -EIO;
 
        /* e.g. XFS meta- & log-data is in slab pages, which have a
         * page_count of 0 and/or have PageSlab() set.
@@ -2756,34 +1504,35 @@ static int _drbd_send_page(struct drbd_conf *mdev, struct page *page,
                return _drbd_no_send_page(mdev, page, offset, size, msg_flags);
 
        msg_flags |= MSG_NOSIGNAL;
-       drbd_update_congested(mdev);
+       drbd_update_congested(mdev->tconn);
        set_fs(KERNEL_DS);
        do {
-               sent = mdev->data.socket->ops->sendpage(mdev->data.socket, page,
-                                                       offset, len,
-                                                       msg_flags);
-               if (sent == -EAGAIN) {
-                       if (we_should_drop_the_connection(mdev,
-                                                         mdev->data.socket))
-                               break;
-                       else
-                               continue;
-               }
+               int sent;
+
+               sent = socket->ops->sendpage(socket, page, offset, len, msg_flags);
                if (sent <= 0) {
+                       if (sent == -EAGAIN) {
+                               if (we_should_drop_the_connection(mdev->tconn, socket))
+                                       break;
+                               continue;
+                       }
                        dev_warn(DEV, "%s: size=%d len=%d sent=%d\n",
                             __func__, (int)size, len, sent);
+                       if (sent < 0)
+                               err = sent;
                        break;
                }
                len    -= sent;
                offset += sent;
        } while (len > 0 /* THINK && mdev->cstate >= C_CONNECTED*/);
        set_fs(oldfs);
-       drbd_clear_flag(mdev, NET_CONGESTED);
+       clear_bit(NET_CONGESTED, &mdev->tconn->flags);
 
-       ok = (len == 0);
-       if (likely(ok))
-               mdev->send_cnt += size>>9;
-       return ok;
+       if (len == 0) {
+               err = 0;
+               mdev->send_cnt += size >> 9;
+       }
+       return err;
 }
 
 static int _drbd_send_bio(struct drbd_conf *mdev, struct bio *bio)
@@ -2792,12 +1541,15 @@ static int _drbd_send_bio(struct drbd_conf *mdev, struct bio *bio)
        int i;
        /* hint all but last page with MSG_MORE */
        bio_for_each_segment(bvec, bio, i) {
-               if (!_drbd_no_send_page(mdev, bvec->bv_page,
-                                    bvec->bv_offset, bvec->bv_len,
-                                    i == bio->bi_vcnt -1 ? 0 : MSG_MORE))
-                       return 0;
+               int err;
+
+               err = _drbd_no_send_page(mdev, bvec->bv_page,
+                                        bvec->bv_offset, bvec->bv_len,
+                                        i == bio->bi_vcnt - 1 ? 0 : MSG_MORE);
+               if (err)
+                       return err;
        }
-       return 1;
+       return 0;
 }
 
 static int _drbd_send_zc_bio(struct drbd_conf *mdev, struct bio *bio)
@@ -2806,32 +1558,40 @@ static int _drbd_send_zc_bio(struct drbd_conf *mdev, struct bio *bio)
        int i;
        /* hint all but last page with MSG_MORE */
        bio_for_each_segment(bvec, bio, i) {
-               if (!_drbd_send_page(mdev, bvec->bv_page,
-                                    bvec->bv_offset, bvec->bv_len,
-                                    i == bio->bi_vcnt -1 ? 0 : MSG_MORE))
-                       return 0;
+               int err;
+
+               err = _drbd_send_page(mdev, bvec->bv_page,
+                                     bvec->bv_offset, bvec->bv_len,
+                                     i == bio->bi_vcnt - 1 ? 0 : MSG_MORE);
+               if (err)
+                       return err;
        }
-       return 1;
+       return 0;
 }
 
-static int _drbd_send_zc_ee(struct drbd_conf *mdev, struct drbd_epoch_entry *e)
+static int _drbd_send_zc_ee(struct drbd_conf *mdev,
+                           struct drbd_peer_request *peer_req)
 {
-       struct page *page = e->pages;
-       unsigned len = e->size;
+       struct page *page = peer_req->pages;
+       unsigned len = peer_req->i.size;
+       int err;
+
        /* hint all but last page with MSG_MORE */
        page_chain_for_each(page) {
                unsigned l = min_t(unsigned, len, PAGE_SIZE);
-               if (!_drbd_send_page(mdev, page, 0, l,
-                               page_chain_next(page) ? MSG_MORE : 0))
-                       return 0;
+
+               err = _drbd_send_page(mdev, page, 0, l,
+                                     page_chain_next(page) ? MSG_MORE : 0);
+               if (err)
+                       return err;
                len -= l;
        }
-       return 1;
+       return 0;
 }
 
 static u32 bio_flags_to_wire(struct drbd_conf *mdev, unsigned long bi_rw)
 {
-       if (mdev->agreed_pro_version >= 95)
+       if (mdev->tconn->agreed_pro_version >= 95)
                return  (bi_rw & REQ_SYNC ? DP_RW_SYNC : 0) |
                        (bi_rw & REQ_FUA ? DP_FUA : 0) |
                        (bi_rw & REQ_FLUSH ? DP_FLUSH : 0) |
@@ -2845,50 +1605,36 @@ static u32 bio_flags_to_wire(struct drbd_conf *mdev, unsigned long bi_rw)
  */
 int drbd_send_dblock(struct drbd_conf *mdev, struct drbd_request *req)
 {
-       int ok = 1;
-       struct p_data p;
+       struct drbd_socket *sock;
+       struct p_data *p;
        unsigned int dp_flags = 0;
-       void *dgb;
        int dgs;
+       int err;
 
-       if (!drbd_get_data_sock(mdev))
-               return 0;
-
-       dgs = (mdev->agreed_pro_version >= 87 && mdev->integrity_w_tfm) ?
-               crypto_hash_digestsize(mdev->integrity_w_tfm) : 0;
-
-       if (req->size <= DRBD_MAX_SIZE_H80_PACKET) {
-               p.head.h80.magic   = BE_DRBD_MAGIC;
-               p.head.h80.command = cpu_to_be16(P_DATA);
-               p.head.h80.length  =
-                       cpu_to_be16(sizeof(p) - sizeof(union p_header) + dgs + req->size);
-       } else {
-               p.head.h95.magic   = BE_DRBD_MAGIC_BIG;
-               p.head.h95.command = cpu_to_be16(P_DATA);
-               p.head.h95.length  =
-                       cpu_to_be32(sizeof(p) - sizeof(union p_header) + dgs + req->size);
-       }
-
-       p.sector   = cpu_to_be64(req->sector);
-       p.block_id = (unsigned long)req;
-       p.seq_num  = cpu_to_be32(atomic_add_return(1, &mdev->packet_seq));
+       sock = &mdev->tconn->data;
+       p = drbd_prepare_command(mdev, sock);
+       dgs = mdev->tconn->integrity_tfm ? crypto_hash_digestsize(mdev->tconn->integrity_tfm) : 0;
 
+       if (!p)
+               return -EIO;
+       p->sector = cpu_to_be64(req->i.sector);
+       p->block_id = (unsigned long)req;
+       p->seq_num = cpu_to_be32(atomic_inc_return(&mdev->packet_seq));
        dp_flags = bio_flags_to_wire(mdev, req->master_bio->bi_rw);
-
        if (mdev->state.conn >= C_SYNC_SOURCE &&
            mdev->state.conn <= C_PAUSED_SYNC_T)
                dp_flags |= DP_MAY_SET_IN_SYNC;
-
-       p.dp_flags = cpu_to_be32(dp_flags);
-       drbd_set_flag(mdev, UNPLUG_REMOTE);
-       ok = (sizeof(p) ==
-               drbd_send(mdev, mdev->data.socket, &p, sizeof(p), dgs ? MSG_MORE : 0));
-       if (ok && dgs) {
-               dgb = mdev->int_dig_out;
-               drbd_csum_bio(mdev, mdev->integrity_w_tfm, req->master_bio, dgb);
-               ok = dgs == drbd_send(mdev, mdev->data.socket, dgb, dgs, 0);
-       }
-       if (ok) {
+       if (mdev->tconn->agreed_pro_version >= 100) {
+               if (req->rq_state & RQ_EXP_RECEIVE_ACK)
+                       dp_flags |= DP_SEND_RECEIVE_ACK;
+               if (req->rq_state & RQ_EXP_WRITE_ACK)
+                       dp_flags |= DP_SEND_WRITE_ACK;
+       }
+       p->dp_flags = cpu_to_be32(dp_flags);
+       if (dgs)
+               drbd_csum_bio(mdev, mdev->tconn->integrity_tfm, req->master_bio, p + 1);
+       err = __send_command(mdev->tconn, mdev->vnr, sock, P_DATA, sizeof(*p) + dgs, NULL, req->i.size);
+       if (!err) {
                /* For protocol A, we have to memcpy the payload into
                 * socket buffers, as we may complete right away
                 * as soon as we handed it over to tcp, at which point the data
@@ -2900,92 +1646,76 @@ int drbd_send_dblock(struct drbd_conf *mdev, struct drbd_request *req)
                 * out ok after sending on this side, but does not fit on the
                 * receiving side, we sure have detected corruption elsewhere.
                 */
-               if (mdev->net_conf->wire_protocol == DRBD_PROT_A || dgs)
-                       ok = _drbd_send_bio(mdev, req->master_bio);
+               if (!(req->rq_state & (RQ_EXP_RECEIVE_ACK | RQ_EXP_WRITE_ACK)) || dgs)
+                       err = _drbd_send_bio(mdev, req->master_bio);
                else
-                       ok = _drbd_send_zc_bio(mdev, req->master_bio);
+                       err = _drbd_send_zc_bio(mdev, req->master_bio);
 
                /* double check digest, sometimes buffers have been modified in flight. */
                if (dgs > 0 && dgs <= 64) {
                        /* 64 byte, 512 bit, is the largest digest size
                         * currently supported in kernel crypto. */
                        unsigned char digest[64];
-                       drbd_csum_bio(mdev, mdev->integrity_w_tfm, req->master_bio, digest);
-                       if (memcmp(mdev->int_dig_out, digest, dgs)) {
+                       drbd_csum_bio(mdev, mdev->tconn->integrity_tfm, req->master_bio, digest);
+                       if (memcmp(p + 1, digest, dgs)) {
                                dev_warn(DEV,
                                        "Digest mismatch, buffer modified by upper layers during write: %llus +%u\n",
-                                       (unsigned long long)req->sector, req->size);
+                                       (unsigned long long)req->i.sector, req->i.size);
                        }
                } /* else if (dgs > 64) {
                     ... Be noisy about digest too large ...
                } */
        }
+       mutex_unlock(&sock->mutex);  /* locked by drbd_prepare_command() */
 
-       drbd_put_data_sock(mdev);
-
-       return ok;
+       return err;
 }
 
 /* answer packet, used to send data back for read requests:
  *  Peer       -> (diskless) R_PRIMARY   (P_DATA_REPLY)
  *  C_SYNC_SOURCE -> C_SYNC_TARGET         (P_RS_DATA_REPLY)
  */
-int drbd_send_block(struct drbd_conf *mdev, enum drbd_packets cmd,
-                   struct drbd_epoch_entry *e)
+int drbd_send_block(struct drbd_conf *mdev, enum drbd_packet cmd,
+                   struct drbd_peer_request *peer_req)
 {
-       int ok;
-       struct p_data p;
-       void *dgb;
+       struct drbd_socket *sock;
+       struct p_data *p;
+       int err;
        int dgs;
 
-       dgs = (mdev->agreed_pro_version >= 87 && mdev->integrity_w_tfm) ?
-               crypto_hash_digestsize(mdev->integrity_w_tfm) : 0;
-
-       if (e->size <= DRBD_MAX_SIZE_H80_PACKET) {
-               p.head.h80.magic   = BE_DRBD_MAGIC;
-               p.head.h80.command = cpu_to_be16(cmd);
-               p.head.h80.length  =
-                       cpu_to_be16(sizeof(p) - sizeof(struct p_header80) + dgs + e->size);
-       } else {
-               p.head.h95.magic   = BE_DRBD_MAGIC_BIG;
-               p.head.h95.command = cpu_to_be16(cmd);
-               p.head.h95.length  =
-                       cpu_to_be32(sizeof(p) - sizeof(struct p_header80) + dgs + e->size);
-       }
-
-       p.sector   = cpu_to_be64(e->sector);
-       p.block_id = e->block_id;
-       /* p.seq_num  = 0;    No sequence numbers here.. */
-
-       /* Only called by our kernel thread.
-        * This one may be interrupted by DRBD_SIG and/or DRBD_SIGKILL
-        * in response to admin command or module unload.
-        */
-       if (!drbd_get_data_sock(mdev))
-               return 0;
+       sock = &mdev->tconn->data;
+       p = drbd_prepare_command(mdev, sock);
 
-       ok = sizeof(p) == drbd_send(mdev, mdev->data.socket, &p, sizeof(p), dgs ? MSG_MORE : 0);
-       if (ok && dgs) {
-               dgb = mdev->int_dig_out;
-               drbd_csum_ee(mdev, mdev->integrity_w_tfm, e, dgb);
-               ok = dgs == drbd_send(mdev, mdev->data.socket, dgb, dgs, 0);
-       }
-       if (ok)
-               ok = _drbd_send_zc_ee(mdev, e);
+       dgs = mdev->tconn->integrity_tfm ? crypto_hash_digestsize(mdev->tconn->integrity_tfm) : 0;
 
-       drbd_put_data_sock(mdev);
+       if (!p)
+               return -EIO;
+       p->sector = cpu_to_be64(peer_req->i.sector);
+       p->block_id = peer_req->block_id;
+       p->seq_num = 0;  /* unused */
+       p->dp_flags = 0;
+       if (dgs)
+               drbd_csum_ee(mdev, mdev->tconn->integrity_tfm, peer_req, p + 1);
+       err = __send_command(mdev->tconn, mdev->vnr, sock, cmd, sizeof(*p) + dgs, NULL, peer_req->i.size);
+       if (!err)
+               err = _drbd_send_zc_ee(mdev, peer_req);
+       mutex_unlock(&sock->mutex);  /* locked by drbd_prepare_command() */
 
-       return ok;
+       return err;
 }
 
-int drbd_send_oos(struct drbd_conf *mdev, struct drbd_request *req)
+int drbd_send_out_of_sync(struct drbd_conf *mdev, struct drbd_request *req)
 {
-       struct p_block_desc p;
-
-       p.sector  = cpu_to_be64(req->sector);
-       p.blksize = cpu_to_be32(req->size);
+       struct drbd_socket *sock;
+       struct p_block_desc *p;
 
-       return drbd_send_cmd(mdev, USE_DATA_SOCKET, P_OUT_OF_SYNC, &p.head, sizeof(p));
+       sock = &mdev->tconn->data;
+       p = drbd_prepare_command(mdev, sock);
+       if (!p)
+               return -EIO;
+       p->sector = cpu_to_be64(req->i.sector);
+       p->blksize = cpu_to_be32(req->i.size);
+       return drbd_send_command(mdev, sock, P_OUT_OF_SYNC, sizeof(*p), NULL, 0);
 }
 
 /*
@@ -3004,7 +1734,7 @@ int drbd_send_oos(struct drbd_conf *mdev, struct drbd_request *req)
 /*
  * you must have down()ed the appropriate [m]sock_mutex elsewhere!
  */
-int drbd_send(struct drbd_conf *mdev, struct socket *sock,
+int drbd_send(struct drbd_tconn *tconn, struct socket *sock,
              void *buf, size_t size, unsigned msg_flags)
 {
        struct kvec iov;
@@ -3012,7 +1742,7 @@ int drbd_send(struct drbd_conf *mdev, struct socket *sock,
        int rv, sent = 0;
 
        if (!sock)
-               return -1000;
+               return -EBADR;
 
        /* THINK  if (signal_pending) return ... ? */
 
@@ -3025,9 +1755,11 @@ int drbd_send(struct drbd_conf *mdev, struct socket *sock,
        msg.msg_controllen = 0;
        msg.msg_flags      = msg_flags | MSG_NOSIGNAL;
 
-       if (sock == mdev->data.socket) {
-               mdev->ko_count = mdev->net_conf->ko_count;
-               drbd_update_congested(mdev);
+       if (sock == tconn->data.socket) {
+               rcu_read_lock();
+               tconn->ko_count = rcu_dereference(tconn->net_conf)->ko_count;
+               rcu_read_unlock();
+               drbd_update_congested(tconn);
        }
        do {
                /* STRANGE
@@ -3041,12 +1773,11 @@ int drbd_send(struct drbd_conf *mdev, struct socket *sock,
  */
                rv = kernel_sendmsg(sock, &msg, &iov, 1, size);
                if (rv == -EAGAIN) {
-                       if (we_should_drop_the_connection(mdev, sock))
+                       if (we_should_drop_the_connection(tconn, sock))
                                break;
                        else
                                continue;
                }
-               D_ASSERT(rv != 0);
                if (rv == -EINTR) {
                        flush_signals(current);
                        rv = 0;
@@ -3058,22 +1789,40 @@ int drbd_send(struct drbd_conf *mdev, struct socket *sock,
                iov.iov_len  -= rv;
        } while (sent < size);
 
-       if (sock == mdev->data.socket)
-               drbd_clear_flag(mdev, NET_CONGESTED);
+       if (sock == tconn->data.socket)
+               clear_bit(NET_CONGESTED, &tconn->flags);
 
        if (rv <= 0) {
                if (rv != -EAGAIN) {
-                       dev_err(DEV, "%s_sendmsg returned %d\n",
-                           sock == mdev->meta.socket ? "msock" : "sock",
-                           rv);
-                       drbd_force_state(mdev, NS(conn, C_BROKEN_PIPE));
+                       conn_err(tconn, "%s_sendmsg returned %d\n",
+                                sock == tconn->meta.socket ? "msock" : "sock",
+                                rv);
+                       conn_request_state(tconn, NS(conn, C_BROKEN_PIPE), CS_HARD);
                } else
-                       drbd_force_state(mdev, NS(conn, C_TIMEOUT));
+                       conn_request_state(tconn, NS(conn, C_TIMEOUT), CS_HARD);
        }
 
        return sent;
 }
 
+/**
+ * drbd_send_all  -  Send an entire buffer
+ *
+ * Returns 0 upon success and a negative error value otherwise.
+ */
+int drbd_send_all(struct drbd_tconn *tconn, struct socket *sock, void *buffer,
+                 size_t size, unsigned msg_flags)
+{
+       int err;
+
+       err = drbd_send(tconn, sock, buffer, size, msg_flags);
+       if (err < 0)
+               return err;
+       if (err != size)
+               return -EIO;
+       return 0;
+}
+
 static int drbd_open(struct block_device *bdev, fmode_t mode)
 {
        struct drbd_conf *mdev = bdev->bd_disk->private_data;
@@ -3081,7 +1830,7 @@ static int drbd_open(struct block_device *bdev, fmode_t mode)
        int rv = 0;
 
        mutex_lock(&drbd_main_mutex);
-       spin_lock_irqsave(&mdev->req_lock, flags);
+       spin_lock_irqsave(&mdev->tconn->req_lock, flags);
        /* to have a stable mdev->state.role
         * and no race with updating open_cnt */
 
@@ -3094,7 +1843,7 @@ static int drbd_open(struct block_device *bdev, fmode_t mode)
 
        if (!rv)
                mdev->open_cnt++;
-       spin_unlock_irqrestore(&mdev->req_lock, flags);
+       spin_unlock_irqrestore(&mdev->tconn->req_lock, flags);
        mutex_unlock(&drbd_main_mutex);
 
        return rv;
@@ -3111,35 +1860,14 @@ static int drbd_release(struct gendisk *gd, fmode_t mode)
 
 static void drbd_set_defaults(struct drbd_conf *mdev)
 {
-       /* This way we get a compile error when sync_conf grows,
-          and we forgot to initialize it here */
-       mdev->sync_conf = (struct syncer_conf) {
-               /* .rate = */           DRBD_RATE_DEF,
-               /* .after = */          DRBD_AFTER_DEF,
-               /* .al_extents = */     DRBD_AL_EXTENTS_DEF,
-               /* .verify_alg = */     {}, 0,
-               /* .cpu_mask = */       {}, 0,
-               /* .csums_alg = */      {}, 0,
-               /* .use_rle = */        0,
-               /* .on_no_data = */     DRBD_ON_NO_DATA_DEF,
-               /* .c_plan_ahead = */   DRBD_C_PLAN_AHEAD_DEF,
-               /* .c_delay_target = */ DRBD_C_DELAY_TARGET_DEF,
-               /* .c_fill_target = */  DRBD_C_FILL_TARGET_DEF,
-               /* .c_max_rate = */     DRBD_C_MAX_RATE_DEF,
-               /* .c_min_rate = */     DRBD_C_MIN_RATE_DEF
-       };
-
-       /* Have to use that way, because the layout differs between
-          big endian and little endian */
-       mdev->state = (union drbd_state) {
+       /* Beware! The actual layout differs
+        * between big endian and little endian */
+       mdev->state = (union drbd_dev_state) {
                { .role = R_SECONDARY,
                  .peer = R_UNKNOWN,
                  .conn = C_STANDALONE,
                  .disk = D_DISKLESS,
                  .pdsk = D_UNKNOWN,
-                 .susp = 0,
-                 .susp_nod = 0,
-                 .susp_fen = 0
                } };
 }
 
@@ -3155,28 +1883,17 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
        atomic_set(&mdev->rs_pending_cnt, 0);
        atomic_set(&mdev->unacked_cnt, 0);
        atomic_set(&mdev->local_cnt, 0);
-       atomic_set(&mdev->net_cnt, 0);
-       atomic_set(&mdev->packet_seq, 0);
-       atomic_set(&mdev->pp_in_use, 0);
        atomic_set(&mdev->pp_in_use_by_net, 0);
        atomic_set(&mdev->rs_sect_in, 0);
        atomic_set(&mdev->rs_sect_ev, 0);
        atomic_set(&mdev->ap_in_flight, 0);
        atomic_set(&mdev->md_io_in_use, 0);
 
-       mutex_init(&mdev->data.mutex);
-       mutex_init(&mdev->meta.mutex);
-       sema_init(&mdev->data.work.s, 0);
-       sema_init(&mdev->meta.work.s, 0);
-       mutex_init(&mdev->state_mutex);
-
-       spin_lock_init(&mdev->data.work.q_lock);
-       spin_lock_init(&mdev->meta.work.q_lock);
+       mutex_init(&mdev->own_state_mutex);
+       mdev->state_mutex = &mdev->own_state_mutex;
 
        spin_lock_init(&mdev->al_lock);
-       spin_lock_init(&mdev->req_lock);
        spin_lock_init(&mdev->peer_seq_lock);
-       spin_lock_init(&mdev->epoch_lock);
 
        INIT_LIST_HEAD(&mdev->active_ee);
        INIT_LIST_HEAD(&mdev->sync_ee);
@@ -3184,8 +1901,6 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
        INIT_LIST_HEAD(&mdev->read_ee);
        INIT_LIST_HEAD(&mdev->net_ee);
        INIT_LIST_HEAD(&mdev->resync_reads);
-       INIT_LIST_HEAD(&mdev->data.work.q);
-       INIT_LIST_HEAD(&mdev->meta.work.q);
        INIT_LIST_HEAD(&mdev->resync_work.list);
        INIT_LIST_HEAD(&mdev->unplug_work.list);
        INIT_LIST_HEAD(&mdev->go_diskless.list);
@@ -3199,6 +1914,14 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
        mdev->md_sync_work.cb = w_md_sync;
        mdev->bm_io_work.w.cb = w_bitmap_io;
        mdev->start_resync_work.cb = w_start_resync;
+
+       mdev->resync_work.mdev  = mdev;
+       mdev->unplug_work.mdev  = mdev;
+       mdev->go_diskless.mdev  = mdev;
+       mdev->md_sync_work.mdev = mdev;
+       mdev->bm_io_work.w.mdev = mdev;
+       mdev->start_resync_work.mdev = mdev;
+
        init_timer(&mdev->resync_timer);
        init_timer(&mdev->md_sync_timer);
        init_timer(&mdev->start_resync_timer);
@@ -3214,17 +1937,10 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
 
        init_waitqueue_head(&mdev->misc_wait);
        init_waitqueue_head(&mdev->state_wait);
-       init_waitqueue_head(&mdev->net_cnt_wait);
        init_waitqueue_head(&mdev->ee_wait);
        init_waitqueue_head(&mdev->al_wait);
        init_waitqueue_head(&mdev->seq_wait);
 
-       drbd_thread_init(mdev, &mdev->receiver, drbdd_init);
-       drbd_thread_init(mdev, &mdev->worker, drbd_worker);
-       drbd_thread_init(mdev, &mdev->asender, drbd_asender);
-
-       mdev->agreed_pro_version = PRO_VERSION_MAX;
-       mdev->write_ordering = WO_bdev_flush;
        mdev->resync_wenr = LC_FREE;
        mdev->peer_max_bio_size = DRBD_MAX_BIO_SIZE_SAFE;
        mdev->local_max_bio_size = DRBD_MAX_BIO_SIZE_SAFE;
@@ -3233,13 +1949,10 @@ void drbd_init_set_defaults(struct drbd_conf *mdev)
 void drbd_mdev_cleanup(struct drbd_conf *mdev)
 {
        int i;
-       if (mdev->receiver.t_state != None)
+       if (mdev->tconn->receiver.t_state != NONE)
                dev_err(DEV, "ASSERT FAILED: receiver t_state == %d expected 0.\n",
-                               mdev->receiver.t_state);
+                               mdev->tconn->receiver.t_state);
 
-       /* no need to lock it, I'm the only thread alive */
-       if (atomic_read(&mdev->current_epoch->epoch_size) !=  0)
-               dev_err(DEV, "epoch_size:%d\n", atomic_read(&mdev->current_epoch->epoch_size));
        mdev->al_writ_cnt  =
        mdev->bm_writ_cnt  =
        mdev->read_cnt     =
@@ -3256,7 +1969,7 @@ void drbd_mdev_cleanup(struct drbd_conf *mdev)
                mdev->rs_mark_left[i] = 0;
                mdev->rs_mark_time[i] = 0;
        }
-       D_ASSERT(mdev->net_conf == NULL);
+       D_ASSERT(mdev->tconn->net_conf == NULL);
 
        drbd_set_my_capacity(mdev, 0);
        if (mdev->bitmap) {
@@ -3265,21 +1978,18 @@ void drbd_mdev_cleanup(struct drbd_conf *mdev)
                drbd_bm_cleanup(mdev);
        }
 
-       drbd_free_resources(mdev);
-       drbd_clear_flag(mdev, AL_SUSPENDED);
+       drbd_free_bc(mdev->ldev);
+       mdev->ldev = NULL;
+
+       clear_bit(AL_SUSPENDED, &mdev->flags);
 
-       /*
-        * currently we drbd_init_ee only on module load, so
-        * we may do drbd_release_ee only on module unload!
-        */
        D_ASSERT(list_empty(&mdev->active_ee));
        D_ASSERT(list_empty(&mdev->sync_ee));
        D_ASSERT(list_empty(&mdev->done_ee));
        D_ASSERT(list_empty(&mdev->read_ee));
        D_ASSERT(list_empty(&mdev->net_ee));
        D_ASSERT(list_empty(&mdev->resync_reads));
-       D_ASSERT(list_empty(&mdev->data.work.q));
-       D_ASSERT(list_empty(&mdev->meta.work.q));
+       D_ASSERT(list_empty(&mdev->tconn->sender_work.q));
        D_ASSERT(list_empty(&mdev->resync_work.list));
        D_ASSERT(list_empty(&mdev->unplug_work.list));
        D_ASSERT(list_empty(&mdev->go_diskless.list));
@@ -3353,7 +2063,7 @@ static int drbd_create_mempools(void)
                goto Enomem;
 
        drbd_ee_cache = kmem_cache_create(
-               "drbd_ee", sizeof(struct drbd_epoch_entry), 0, 0, NULL);
+               "drbd_ee", sizeof(struct drbd_peer_request), 0, 0, NULL);
        if (drbd_ee_cache == NULL)
                goto Enomem;
 
@@ -3368,11 +2078,9 @@ static int drbd_create_mempools(void)
                goto Enomem;
 
        /* mempools */
-#ifdef COMPAT_HAVE_BIOSET_CREATE
        drbd_md_io_bio_set = bioset_create(DRBD_MIN_POOL_PAGES, 0);
        if (drbd_md_io_bio_set == NULL)
                goto Enomem;
-#endif
 
        drbd_md_io_page_pool = mempool_create_page_pool(DRBD_MIN_POOL_PAGES, 0);
        if (drbd_md_io_page_pool == NULL)
@@ -3421,73 +2129,53 @@ static struct notifier_block drbd_notifier = {
        .notifier_call = drbd_notify_sys,
 };
 
-static void drbd_release_ee_lists(struct drbd_conf *mdev)
+static void drbd_release_all_peer_reqs(struct drbd_conf *mdev)
 {
        int rr;
 
-       rr = drbd_release_ee(mdev, &mdev->active_ee);
+       rr = drbd_free_peer_reqs(mdev, &mdev->active_ee);
        if (rr)
                dev_err(DEV, "%d EEs in active list found!\n", rr);
 
-       rr = drbd_release_ee(mdev, &mdev->sync_ee);
+       rr = drbd_free_peer_reqs(mdev, &mdev->sync_ee);
        if (rr)
                dev_err(DEV, "%d EEs in sync list found!\n", rr);
 
-       rr = drbd_release_ee(mdev, &mdev->read_ee);
+       rr = drbd_free_peer_reqs(mdev, &mdev->read_ee);
        if (rr)
                dev_err(DEV, "%d EEs in read list found!\n", rr);
 
-       rr = drbd_release_ee(mdev, &mdev->done_ee);
+       rr = drbd_free_peer_reqs(mdev, &mdev->done_ee);
        if (rr)
                dev_err(DEV, "%d EEs in done list found!\n", rr);
 
-       rr = drbd_release_ee(mdev, &mdev->net_ee);
+       rr = drbd_free_peer_reqs(mdev, &mdev->net_ee);
        if (rr)
                dev_err(DEV, "%d EEs in net list found!\n", rr);
 }
 
-/* caution. no locking.
- * currently only used from module cleanup code. */
-static void drbd_delete_device(unsigned int minor)
+/* caution. no locking. */
+void drbd_minor_destroy(struct kref *kref)
 {
-       struct drbd_conf *mdev = minor_to_mdev(minor);
-
-       if (!mdev)
-               return;
+       struct drbd_conf *mdev = container_of(kref, struct drbd_conf, kref);
+       struct drbd_tconn *tconn = mdev->tconn;
 
        del_timer_sync(&mdev->request_timer);
 
        /* paranoia asserts */
-       if (mdev->open_cnt != 0)
-               dev_err(DEV, "open_cnt = %d in %s:%u", mdev->open_cnt,
-                               __FILE__ , __LINE__);
-
-       ERR_IF (!list_empty(&mdev->data.work.q)) {
-               struct list_head *lp;
-               list_for_each(lp, &mdev->data.work.q) {
-                       dev_err(DEV, "lp = %p\n", lp);
-               }
-       };
+       D_ASSERT(mdev->open_cnt == 0);
        /* end paranoia asserts */
 
-       del_gendisk(mdev->vdisk);
-
        /* cleanup stuff that may have been allocated during
         * device (re-)configuration or state changes */
 
        if (mdev->this_bdev)
                bdput(mdev->this_bdev);
 
-       drbd_free_resources(mdev);
+       drbd_free_bc(mdev->ldev);
+       mdev->ldev = NULL;
 
-       drbd_release_ee_lists(mdev);
-
-       /* should be freed on disconnect? */
-       kfree(mdev->ee_hash);
-       /*
-       mdev->ee_hash_s = 0;
-       mdev->ee_hash = NULL;
-       */
+       drbd_release_all_peer_reqs(mdev);
 
        lc_destroy(mdev->act_log);
        lc_destroy(mdev->resync);
@@ -3495,19 +2183,101 @@ static void drbd_delete_device(unsigned int minor)
        kfree(mdev->p_uuid);
        /* mdev->p_uuid = NULL; */
 
-       kfree(mdev->int_dig_out);
-       kfree(mdev->int_dig_in);
-       kfree(mdev->int_dig_vv);
+       if (mdev->bitmap) /* should no longer be there. */
+               drbd_bm_cleanup(mdev);
+       __free_page(mdev->md_io_page);
+       put_disk(mdev->vdisk);
+       blk_cleanup_queue(mdev->rq_queue);
+       kfree(mdev->rs_plan_s);
+       kfree(mdev);
+
+       kref_put(&tconn->kref, &conn_destroy);
+}
+
+/* One global retry thread, if we need to push back some bio and have it
+ * reinserted through our make request function.
+ */
+static struct retry_worker {
+       struct workqueue_struct *wq;
+       struct work_struct worker;
+
+       spinlock_t lock;
+       struct list_head writes;
+} retry;
+
+static void do_retry(struct work_struct *ws)
+{
+       struct retry_worker *retry = container_of(ws, struct retry_worker, worker);
+       LIST_HEAD(writes);
+       struct drbd_request *req, *tmp;
+
+       spin_lock_irq(&retry->lock);
+       list_splice_init(&retry->writes, &writes);
+       spin_unlock_irq(&retry->lock);
+
+       list_for_each_entry_safe(req, tmp, &writes, tl_requests) {
+               struct drbd_conf *mdev = req->w.mdev;
+               struct bio *bio = req->master_bio;
+               unsigned long start_time = req->start_time;
+               bool expected;
+
+               expected = 
+                       expect(atomic_read(&req->completion_ref) == 0) &&
+                       expect(req->rq_state & RQ_POSTPONED) &&
+                       expect((req->rq_state & RQ_LOCAL_PENDING) == 0 ||
+                               (req->rq_state & RQ_LOCAL_ABORTED) != 0);
+
+               if (!expected)
+                       dev_err(DEV, "req=%p completion_ref=%d rq_state=%x\n",
+                               req, atomic_read(&req->completion_ref),
+                               req->rq_state);
+
+               /* We still need to put one kref associated with the
+                * "completion_ref" going zero in the code path that queued it
+                * here.  The request object may still be referenced by a
+                * frozen local req->private_bio, in case we force-detached.
+                */
+               kref_put(&req->kref, drbd_req_destroy);
+
+               /* A single suspended or otherwise blocking device may stall
+                * all others as well.  Fortunately, this code path is to
+                * recover from a situation that "should not happen":
+                * concurrent writes in multi-primary setup.
+                * In a "normal" lifecycle, this workqueue is supposed to be
+                * destroyed without ever doing anything.
+                * If it turns out to be an issue anyways, we can do per
+                * resource (replication group) or per device (minor) retry
+                * workqueues instead.
+                */
+
+               /* We are not just doing generic_make_request(),
+                * as we want to keep the start_time information. */
+               inc_ap_bio(mdev);
+               __drbd_make_request(mdev, bio, start_time);
+       }
+}
+
+void drbd_restart_request(struct drbd_request *req)
+{
+       unsigned long flags;
+       spin_lock_irqsave(&retry.lock, flags);
+       list_move_tail(&req->tl_requests, &retry.writes);
+       spin_unlock_irqrestore(&retry.lock, flags);
+
+       /* Drop the extra reference that would otherwise
+        * have been dropped by complete_master_bio.
+        * do_retry() needs to grab a new one. */
+       dec_ap_bio(req->w.mdev);
 
-       /* cleanup the rest that has been
-        * allocated from drbd_new_device
-        * and actually free the mdev itself */
-       drbd_free_mdev(mdev);
+       queue_work(retry.wq, &retry.worker);
 }
 
+
 static void drbd_cleanup(void)
 {
        unsigned int i;
+       struct drbd_conf *mdev;
+       struct drbd_tconn *tconn, *tmp;
 
        unregister_reboot_notifier(&drbd_notifier);
 
@@ -3522,19 +2292,31 @@ static void drbd_cleanup(void)
        if (drbd_proc)
                remove_proc_entry("drbd", NULL);
 
-       drbd_nl_cleanup();
+       if (retry.wq)
+               destroy_workqueue(retry.wq);
+
+       drbd_genl_unregister();
 
-       if (minor_table) {
-               i = minor_count;
-               while (i--)
-                       drbd_delete_device(i);
-               drbd_destroy_mempools();
+       idr_for_each_entry(&minors, mdev, i) {
+               idr_remove(&minors, mdev_to_minor(mdev));
+               idr_remove(&mdev->tconn->volumes, mdev->vnr);
+               del_gendisk(mdev->vdisk);
+               /* synchronize_rcu(); No other threads running at this point */
+               kref_put(&mdev->kref, &drbd_minor_destroy);
        }
 
-       kfree(minor_table);
+       /* not _rcu since, no other updater anymore. Genl already unregistered */
+       list_for_each_entry_safe(tconn, tmp, &drbd_tconns, all_tconn) {
+               list_del(&tconn->all_tconn); /* not _rcu no proc, not other threads */
+               /* synchronize_rcu(); */
+               kref_put(&tconn->kref, &conn_destroy);
+       }
 
+       drbd_destroy_mempools();
        unregister_blkdev(DRBD_MAJOR, "drbd");
 
+       idr_destroy(&minors);
+
        printk(KERN_INFO "drbd: module cleanup done.\n");
 }
 
@@ -3559,7 +2341,7 @@ static int drbd_congested(void *congested_data, int bdi_bits)
                goto out;
        }
 
-       if (drbd_test_flag(mdev, CALLBACK_PENDING)) {
+       if (test_bit(CALLBACK_PENDING, &mdev->tconn->flags)) {
                r |= (1 << BDI_async_congested);
                /* Without good local data, we would need to read from remote,
                 * and that would need the worker thread as well, which is
@@ -3583,7 +2365,7 @@ static int drbd_congested(void *congested_data, int bdi_bits)
                        reason = 'b';
        }
 
-       if (bdi_bits & (1 << BDI_async_congested) && drbd_test_flag(mdev, NET_CONGESTED)) {
+       if (bdi_bits & (1 << BDI_async_congested) && test_bit(NET_CONGESTED, &mdev->tconn->flags)) {
                r |= (1 << BDI_async_congested);
                reason = reason == 'b' ? 'a' : 'n';
        }
@@ -3593,20 +2375,243 @@ out:
        return r;
 }
 
-struct drbd_conf *drbd_new_device(unsigned int minor)
+static void drbd_init_workqueue(struct drbd_work_queue* wq)
+{
+       spin_lock_init(&wq->q_lock);
+       INIT_LIST_HEAD(&wq->q);
+       init_waitqueue_head(&wq->q_wait);
+}
+
+struct drbd_tconn *conn_get_by_name(const char *name)
+{
+       struct drbd_tconn *tconn;
+
+       if (!name || !name[0])
+               return NULL;
+
+       rcu_read_lock();
+       list_for_each_entry_rcu(tconn, &drbd_tconns, all_tconn) {
+               if (!strcmp(tconn->name, name)) {
+                       kref_get(&tconn->kref);
+                       goto found;
+               }
+       }
+       tconn = NULL;
+found:
+       rcu_read_unlock();
+       return tconn;
+}
+
+struct drbd_tconn *conn_get_by_addrs(void *my_addr, int my_addr_len,
+                                    void *peer_addr, int peer_addr_len)
+{
+       struct drbd_tconn *tconn;
+
+       rcu_read_lock();
+       list_for_each_entry_rcu(tconn, &drbd_tconns, all_tconn) {
+               if (tconn->my_addr_len == my_addr_len &&
+                   tconn->peer_addr_len == peer_addr_len &&
+                   !memcmp(&tconn->my_addr, my_addr, my_addr_len) &&
+                   !memcmp(&tconn->peer_addr, peer_addr, peer_addr_len)) {
+                       kref_get(&tconn->kref);
+                       goto found;
+               }
+       }
+       tconn = NULL;
+found:
+       rcu_read_unlock();
+       return tconn;
+}
+
+static int drbd_alloc_socket(struct drbd_socket *socket)
+{
+       socket->rbuf = (void *) __get_free_page(GFP_KERNEL);
+       if (!socket->rbuf)
+               return -ENOMEM;
+       socket->sbuf = (void *) __get_free_page(GFP_KERNEL);
+       if (!socket->sbuf)
+               return -ENOMEM;
+       return 0;
+}
+
+static void drbd_free_socket(struct drbd_socket *socket)
+{
+       free_page((unsigned long) socket->sbuf);
+       free_page((unsigned long) socket->rbuf);
+}
+
+void conn_free_crypto(struct drbd_tconn *tconn)
+{
+       drbd_free_sock(tconn);
+
+       crypto_free_hash(tconn->csums_tfm);
+       crypto_free_hash(tconn->verify_tfm);
+       crypto_free_hash(tconn->cram_hmac_tfm);
+       crypto_free_hash(tconn->integrity_tfm);
+       crypto_free_hash(tconn->peer_integrity_tfm);
+       kfree(tconn->int_dig_in);
+       kfree(tconn->int_dig_vv);
+
+       tconn->csums_tfm = NULL;
+       tconn->verify_tfm = NULL;
+       tconn->cram_hmac_tfm = NULL;
+       tconn->integrity_tfm = NULL;
+       tconn->peer_integrity_tfm = NULL;
+       tconn->int_dig_in = NULL;
+       tconn->int_dig_vv = NULL;
+}
+
+int set_resource_options(struct drbd_tconn *tconn, struct res_opts *res_opts)
+{
+       cpumask_var_t new_cpu_mask;
+       int err;
+
+       if (!zalloc_cpumask_var(&new_cpu_mask, GFP_KERNEL))
+               return -ENOMEM;
+               /*
+               retcode = ERR_NOMEM;
+               drbd_msg_put_info("unable to allocate cpumask");
+               */
+
+       /* silently ignore cpu mask on UP kernel */
+       if (nr_cpu_ids > 1 && res_opts->cpu_mask[0] != 0) {
+               /* FIXME: Get rid of constant 32 here */
+               err = bitmap_parse(res_opts->cpu_mask, 32,
+                                  cpumask_bits(new_cpu_mask), nr_cpu_ids);
+               if (err) {
+                       conn_warn(tconn, "bitmap_parse() failed with %d\n", err);
+                       /* retcode = ERR_CPU_MASK_PARSE; */
+                       goto fail;
+               }
+       }
+       tconn->res_opts = *res_opts;
+       if (!cpumask_equal(tconn->cpu_mask, new_cpu_mask)) {
+               cpumask_copy(tconn->cpu_mask, new_cpu_mask);
+               drbd_calc_cpu_mask(tconn);
+               tconn->receiver.reset_cpu_mask = 1;
+               tconn->asender.reset_cpu_mask = 1;
+               tconn->worker.reset_cpu_mask = 1;
+       }
+       err = 0;
+
+fail:
+       free_cpumask_var(new_cpu_mask);
+       return err;
+
+}
+
+/* caller must be under genl_lock() */
+struct drbd_tconn *conn_create(const char *name, struct res_opts *res_opts)
+{
+       struct drbd_tconn *tconn;
+
+       tconn = kzalloc(sizeof(struct drbd_tconn), GFP_KERNEL);
+       if (!tconn)
+               return NULL;
+
+       tconn->name = kstrdup(name, GFP_KERNEL);
+       if (!tconn->name)
+               goto fail;
+
+       if (drbd_alloc_socket(&tconn->data))
+               goto fail;
+       if (drbd_alloc_socket(&tconn->meta))
+               goto fail;
+
+       if (!zalloc_cpumask_var(&tconn->cpu_mask, GFP_KERNEL))
+               goto fail;
+
+       if (set_resource_options(tconn, res_opts))
+               goto fail;
+
+       tconn->current_epoch = kzalloc(sizeof(struct drbd_epoch), GFP_KERNEL);
+       if (!tconn->current_epoch)
+               goto fail;
+
+       INIT_LIST_HEAD(&tconn->transfer_log);
+
+       INIT_LIST_HEAD(&tconn->current_epoch->list);
+       tconn->epochs = 1;
+       spin_lock_init(&tconn->epoch_lock);
+       tconn->write_ordering = WO_bdev_flush;
+
+       tconn->send.seen_any_write_yet = false;
+       tconn->send.current_epoch_nr = 0;
+       tconn->send.current_epoch_writes = 0;
+
+       tconn->cstate = C_STANDALONE;
+       mutex_init(&tconn->cstate_mutex);
+       spin_lock_init(&tconn->req_lock);
+       mutex_init(&tconn->conf_update);
+       init_waitqueue_head(&tconn->ping_wait);
+       idr_init(&tconn->volumes);
+
+       drbd_init_workqueue(&tconn->sender_work);
+       mutex_init(&tconn->data.mutex);
+       mutex_init(&tconn->meta.mutex);
+
+       drbd_thread_init(tconn, &tconn->receiver, drbdd_init, "receiver");
+       drbd_thread_init(tconn, &tconn->worker, drbd_worker, "worker");
+       drbd_thread_init(tconn, &tconn->asender, drbd_asender, "asender");
+
+       kref_init(&tconn->kref);
+       list_add_tail_rcu(&tconn->all_tconn, &drbd_tconns);
+
+       return tconn;
+
+fail:
+       kfree(tconn->current_epoch);
+       free_cpumask_var(tconn->cpu_mask);
+       drbd_free_socket(&tconn->meta);
+       drbd_free_socket(&tconn->data);
+       kfree(tconn->name);
+       kfree(tconn);
+
+       return NULL;
+}
+
+void conn_destroy(struct kref *kref)
+{
+       struct drbd_tconn *tconn = container_of(kref, struct drbd_tconn, kref);
+
+       if (atomic_read(&tconn->current_epoch->epoch_size) !=  0)
+               conn_err(tconn, "epoch_size:%d\n", atomic_read(&tconn->current_epoch->epoch_size));
+       kfree(tconn->current_epoch);
+
+       idr_destroy(&tconn->volumes);
+
+       free_cpumask_var(tconn->cpu_mask);
+       drbd_free_socket(&tconn->meta);
+       drbd_free_socket(&tconn->data);
+       kfree(tconn->name);
+       kfree(tconn->int_dig_in);
+       kfree(tconn->int_dig_vv);
+       kfree(tconn);
+}
+
+enum drbd_ret_code conn_new_minor(struct drbd_tconn *tconn, unsigned int minor, int vnr)
 {
        struct drbd_conf *mdev;
        struct gendisk *disk;
        struct request_queue *q;
+       int vnr_got = vnr;
+       int minor_got = minor;
+       enum drbd_ret_code err = ERR_NOMEM;
+
+       mdev = minor_to_mdev(minor);
+       if (mdev)
+               return ERR_MINOR_EXISTS;
 
        /* GFP_KERNEL, we are outside of all write-out paths */
        mdev = kzalloc(sizeof(struct drbd_conf), GFP_KERNEL);
        if (!mdev)
-               return NULL;
-       if (!zalloc_cpumask_var(&mdev->cpu_mask, GFP_KERNEL))
-               goto out_no_cpumask;
+               return ERR_NOMEM;
+
+       kref_get(&tconn->kref);
+       mdev->tconn = tconn;
 
        mdev->minor = minor;
+       mdev->vnr = vnr;
 
        drbd_init_set_defaults(mdev);
 
@@ -3644,7 +2649,7 @@ struct drbd_conf *drbd_new_device(unsigned int minor)
        blk_queue_max_hw_sectors(q, DRBD_MAX_BIO_SIZE_SAFE >> 8);
        blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
        blk_queue_merge_bvec(q, drbd_merge_bvec);
-       q->queue_lock = &mdev->req_lock;
+       q->queue_lock = &mdev->tconn->req_lock; /* needed since we use */
 
        mdev->md_io_page = alloc_page(GFP_KERNEL);
        if (!mdev->md_io_page)
@@ -3652,30 +2657,44 @@ struct drbd_conf *drbd_new_device(unsigned int minor)
 
        if (drbd_bm_init(mdev))
                goto out_no_bitmap;
-       /* no need to lock access, we are still initializing this minor device. */
-       if (!tl_init(mdev))
-               goto out_no_tl;
-
-       mdev->app_reads_hash = kzalloc(APP_R_HSIZE*sizeof(void *), GFP_KERNEL);
-       if (!mdev->app_reads_hash)
-               goto out_no_app_reads;
-
-       mdev->current_epoch = kzalloc(sizeof(struct drbd_epoch), GFP_KERNEL);
-       if (!mdev->current_epoch)
-               goto out_no_epoch;
-
-       INIT_LIST_HEAD(&mdev->current_epoch->list);
-       mdev->epochs = 1;
-
-       return mdev;
-
-/* out_whatever_else:
-       kfree(mdev->current_epoch); */
-out_no_epoch:
-       kfree(mdev->app_reads_hash);
-out_no_app_reads:
-       tl_cleanup(mdev);
-out_no_tl:
+       mdev->read_requests = RB_ROOT;
+       mdev->write_requests = RB_ROOT;
+
+       if (!idr_pre_get(&minors, GFP_KERNEL))
+               goto out_no_minor_idr;
+       if (idr_get_new_above(&minors, mdev, minor, &minor_got))
+               goto out_no_minor_idr;
+       if (minor_got != minor) {
+               err = ERR_MINOR_EXISTS;
+               drbd_msg_put_info("requested minor exists already");
+               goto out_idr_remove_minor;
+       }
+
+       if (!idr_pre_get(&tconn->volumes, GFP_KERNEL))
+               goto out_idr_remove_minor;
+       if (idr_get_new_above(&tconn->volumes, mdev, vnr, &vnr_got))
+               goto out_idr_remove_minor;
+       if (vnr_got != vnr) {
+               err = ERR_INVALID_REQUEST;
+               drbd_msg_put_info("requested volume exists already");
+               goto out_idr_remove_vol;
+       }
+       add_disk(disk);
+       kref_init(&mdev->kref); /* one ref for both idrs and the the add_disk */
+
+       /* inherit the connection state */
+       mdev->state.conn = tconn->cstate;
+       if (mdev->state.conn == C_WF_REPORT_PARAMS)
+               drbd_connected(mdev);
+
+       return NO_ERROR;
+
+out_idr_remove_vol:
+       idr_remove(&tconn->volumes, vnr_got);
+out_idr_remove_minor:
+       idr_remove(&minors, minor_got);
+       synchronize_rcu();
+out_no_minor_idr:
        drbd_bm_cleanup(mdev);
 out_no_bitmap:
        __free_page(mdev->md_io_page);
@@ -3684,55 +2703,25 @@ out_no_io_page:
 out_no_disk:
        blk_cleanup_queue(q);
 out_no_q:
-       free_cpumask_var(mdev->cpu_mask);
-out_no_cpumask:
-       kfree(mdev);
-       return NULL;
-}
-
-/* counterpart of drbd_new_device.
- * last part of drbd_delete_device. */
-void drbd_free_mdev(struct drbd_conf *mdev)
-{
-       kfree(mdev->current_epoch);
-       kfree(mdev->app_reads_hash);
-       tl_cleanup(mdev);
-       if (mdev->bitmap) /* should no longer be there. */
-               drbd_bm_cleanup(mdev);
-       __free_page(mdev->md_io_page);
-       put_disk(mdev->vdisk);
-       blk_cleanup_queue(mdev->rq_queue);
-       free_cpumask_var(mdev->cpu_mask);
-       drbd_free_tl_hash(mdev);
        kfree(mdev);
+       kref_put(&tconn->kref, &conn_destroy);
+       return err;
 }
 
-
 int __init drbd_init(void)
 {
        int err;
 
-       if (sizeof(struct p_handshake) != 80) {
-               printk(KERN_ERR
-                      "drbd: never change the size or layout "
-                      "of the HandShake packet.\n");
-               return -EINVAL;
-       }
-
        if (minor_count < DRBD_MINOR_COUNT_MIN || minor_count > DRBD_MINOR_COUNT_MAX) {
                printk(KERN_ERR
-                       "drbd: invalid minor_count (%d)\n", minor_count);
+                      "drbd: invalid minor_count (%d)\n", minor_count);
 #ifdef MODULE
                return -EINVAL;
 #else
-               minor_count = 8;
+               minor_count = DRBD_MINOR_COUNT_DEF;
 #endif
        }
 
-       err = drbd_nl_init();
-       if (err)
-               return err;
-
        err = register_blkdev(DRBD_MAJOR, "drbd");
        if (err) {
                printk(KERN_ERR
@@ -3741,6 +2730,13 @@ int __init drbd_init(void)
                return err;
        }
 
+       err = drbd_genl_register();
+       if (err) {
+               printk(KERN_ERR "drbd: unable to register generic netlink family\n");
+               goto fail;
+       }
+
+
        register_reboot_notifier(&drbd_notifier);
 
        /*
@@ -3751,22 +2747,29 @@ int __init drbd_init(void)
        init_waitqueue_head(&drbd_pp_wait);
 
        drbd_proc = NULL; /* play safe for drbd_cleanup */
-       minor_table = kzalloc(sizeof(struct drbd_conf *)*minor_count,
-                               GFP_KERNEL);
-       if (!minor_table)
-               goto Enomem;
+       idr_init(&minors);
 
        err = drbd_create_mempools();
        if (err)
-               goto Enomem;
+               goto fail;
 
        drbd_proc = proc_create_data("drbd", S_IFREG | S_IRUGO , NULL, &drbd_proc_fops, NULL);
        if (!drbd_proc) {
                printk(KERN_ERR "drbd: unable to register proc file\n");
-               goto Enomem;
+               goto fail;
        }
 
        rwlock_init(&global_state_lock);
+       INIT_LIST_HEAD(&drbd_tconns);
+
+       retry.wq = create_singlethread_workqueue("drbd-reissue");
+       if (!retry.wq) {
+               printk(KERN_ERR "drbd: unable to create retry workqueue\n");
+               goto fail;
+       }
+       INIT_WORK(&retry.worker, do_retry);
+       spin_lock_init(&retry.lock);
+       INIT_LIST_HEAD(&retry.writes);
 
        printk(KERN_INFO "drbd: initialized. "
               "Version: " REL_VERSION " (api:%d/proto:%d-%d)\n",
@@ -3774,11 +2777,10 @@ int __init drbd_init(void)
        printk(KERN_INFO "drbd: %s\n", drbd_buildtag());
        printk(KERN_INFO "drbd: registered as block device major %d\n",
                DRBD_MAJOR);
-       printk(KERN_INFO "drbd: minor_table @ 0x%p\n", minor_table);
 
        return 0; /* Success! */
 
-Enomem:
+fail:
        drbd_cleanup();
        if (err == -ENOMEM)
                /* currently always the case */
@@ -3799,47 +2801,42 @@ void drbd_free_bc(struct drbd_backing_dev *ldev)
        kfree(ldev);
 }
 
-void drbd_free_sock(struct drbd_conf *mdev)
+void drbd_free_sock(struct drbd_tconn *tconn)
 {
-       if (mdev->data.socket) {
-               mutex_lock(&mdev->data.mutex);
-               kernel_sock_shutdown(mdev->data.socket, SHUT_RDWR);
-               sock_release(mdev->data.socket);
-               mdev->data.socket = NULL;
-               mutex_unlock(&mdev->data.mutex);
+       if (tconn->data.socket) {
+               mutex_lock(&tconn->data.mutex);
+               kernel_sock_shutdown(tconn->data.socket, SHUT_RDWR);
+               sock_release(tconn->data.socket);
+               tconn->data.socket = NULL;
+               mutex_unlock(&tconn->data.mutex);
        }
-       if (mdev->meta.socket) {
-               mutex_lock(&mdev->meta.mutex);
-               kernel_sock_shutdown(mdev->meta.socket, SHUT_RDWR);
-               sock_release(mdev->meta.socket);
-               mdev->meta.socket = NULL;
-               mutex_unlock(&mdev->meta.mutex);
+       if (tconn->meta.socket) {
+               mutex_lock(&tconn->meta.mutex);
+               kernel_sock_shutdown(tconn->meta.socket, SHUT_RDWR);
+               sock_release(tconn->meta.socket);
+               tconn->meta.socket = NULL;
+               mutex_unlock(&tconn->meta.mutex);
        }
 }
 
+/* meta data management */
 
-void drbd_free_resources(struct drbd_conf *mdev)
+void conn_md_sync(struct drbd_tconn *tconn)
 {
-       crypto_free_hash(mdev->csums_tfm);
-       mdev->csums_tfm = NULL;
-       crypto_free_hash(mdev->verify_tfm);
-       mdev->verify_tfm = NULL;
-       crypto_free_hash(mdev->cram_hmac_tfm);
-       mdev->cram_hmac_tfm = NULL;
-       crypto_free_hash(mdev->integrity_w_tfm);
-       mdev->integrity_w_tfm = NULL;
-       crypto_free_hash(mdev->integrity_r_tfm);
-       mdev->integrity_r_tfm = NULL;
-
-       drbd_free_sock(mdev);
+       struct drbd_conf *mdev;
+       int vnr;
 
-       __no_warn(local,
-                 drbd_free_bc(mdev->ldev);
-                 mdev->ldev = NULL;);
+       rcu_read_lock();
+       idr_for_each_entry(&tconn->volumes, mdev, vnr) {
+               kref_get(&mdev->kref);
+               rcu_read_unlock();
+               drbd_md_sync(mdev);
+               kref_put(&mdev->kref, &drbd_minor_destroy);
+               rcu_read_lock();
+       }
+       rcu_read_unlock();
 }
 
-/* meta data management */
-
 struct meta_data_on_disk {
        u64 la_size;           /* last agreed size. */
        u64 uuid[UI_SIZE];   /* UUIDs. */
@@ -3850,7 +2847,7 @@ struct meta_data_on_disk {
        u32 md_size_sect;
        u32 al_offset;         /* offset to this block */
        u32 al_nr_extents;     /* important for restoring the AL */
-             /* `-- act_log->nr_elements <-- sync_conf.al_extents */
+             /* `-- act_log->nr_elements <-- ldev->dc.al_extents */
        u32 bm_offset;         /* offset to the bitmap, from here */
        u32 bm_bytes_per_bit;  /* BM_BLOCK_SIZE */
        u32 la_peer_max_bio_size;   /* last peer max_bio_size */
@@ -3870,7 +2867,7 @@ void drbd_md_sync(struct drbd_conf *mdev)
 
        del_timer(&mdev->md_sync_timer);
        /* timer may be rearmed by drbd_md_mark_dirty() now. */
-       if (!drbd_test_and_clear_flag(mdev, MD_DIRTY))
+       if (!test_and_clear_bit(MD_DIRTY, &mdev->flags))
                return;
 
        /* We use here D_FAILED and not D_ATTACHING because we try to write
@@ -3888,7 +2885,7 @@ void drbd_md_sync(struct drbd_conf *mdev)
        for (i = UI_CURRENT; i < UI_SIZE; i++)
                buffer->uuid[i] = cpu_to_be64(mdev->ldev->md.uuid[i]);
        buffer->flags = cpu_to_be32(mdev->ldev->md.flags);
-       buffer->magic = cpu_to_be32(DRBD_MD_MAGIC);
+       buffer->magic = cpu_to_be32(DRBD_MD_MAGIC_84_UNCLEAN);
 
        buffer->md_size_sect  = cpu_to_be32(mdev->ldev->md.md_size_sect);
        buffer->al_offset     = cpu_to_be32(mdev->ldev->md.al_offset);
@@ -3902,7 +2899,7 @@ void drbd_md_sync(struct drbd_conf *mdev)
        D_ASSERT(drbd_md_ss__(mdev, mdev->ldev) == mdev->ldev->md.md_offset);
        sector = mdev->ldev->md.md_offset;
 
-       if (!drbd_md_sync_page_io(mdev, mdev->ldev, sector, WRITE)) {
+       if (drbd_md_sync_page_io(mdev, mdev->ldev, sector, WRITE)) {
                /* this was a try anyways ... */
                dev_err(DEV, "meta data update failed!\n");
                drbd_chk_io_error(mdev, 1, DRBD_META_IO_ERROR);
@@ -3923,11 +2920,12 @@ out:
  * @bdev:      Device from which the meta data should be read in.
  *
  * Return 0 (NO_ERROR) on success, and an enum drbd_ret_code in case
- * something goes wrong.  Currently only: ERR_IO_MD_DISK, ERR_MD_INVALID.
+ * something goes wrong.
  */
 int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
 {
        struct meta_data_on_disk *buffer;
+       u32 magic, flags;
        int i, rv = NO_ERROR;
 
        if (!get_ldev_if_state(mdev, D_ATTACHING))
@@ -3937,7 +2935,7 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
        if (!buffer)
                goto out;
 
-       if (!drbd_md_sync_page_io(mdev, bdev, bdev->md.md_offset, READ)) {
+       if (drbd_md_sync_page_io(mdev, bdev, bdev->md.md_offset, READ)) {
                /* NOTE: can't do normal error processing here as this is
                   called BEFORE disk is attached */
                dev_err(DEV, "Error while reading metadata.\n");
@@ -3945,8 +2943,20 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
                goto err;
        }
 
-       if (be32_to_cpu(buffer->magic) != DRBD_MD_MAGIC) {
-               dev_err(DEV, "Error while reading metadata, magic not found.\n");
+       magic = be32_to_cpu(buffer->magic);
+       flags = be32_to_cpu(buffer->flags);
+       if (magic == DRBD_MD_MAGIC_84_UNCLEAN ||
+           (magic == DRBD_MD_MAGIC_08 && !(flags & MDF_AL_CLEAN))) {
+                       /* btw: that's Activity Log clean, not "all" clean. */
+               dev_err(DEV, "Found unclean meta data. Did you \"drbdadm apply-al\"?\n");
+               rv = ERR_MD_UNCLEAN;
+               goto err;
+       }
+       if (magic != DRBD_MD_MAGIC_08) {
+               if (magic == DRBD_MD_MAGIC_07)
+                       dev_err(DEV, "Found old (0.7) meta data magic. Did you \"drbdadm create-md\"?\n");
+               else
+                       dev_err(DEV, "Meta data magic not found. Did you \"drbdadm create-md\"?\n");
                rv = ERR_MD_INVALID;
                goto err;
        }
@@ -3980,20 +2990,16 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
        for (i = UI_CURRENT; i < UI_SIZE; i++)
                bdev->md.uuid[i] = be64_to_cpu(buffer->uuid[i]);
        bdev->md.flags = be32_to_cpu(buffer->flags);
-       mdev->sync_conf.al_extents = be32_to_cpu(buffer->al_nr_extents);
        bdev->md.device_uuid = be64_to_cpu(buffer->device_uuid);
 
-       spin_lock_irq(&mdev->req_lock);
+       spin_lock_irq(&mdev->tconn->req_lock);
        if (mdev->state.conn < C_CONNECTED) {
                unsigned int peer;
                peer = be32_to_cpu(buffer->la_peer_max_bio_size);
                peer = max(peer, DRBD_MAX_BIO_SIZE_SAFE);
                mdev->peer_max_bio_size = peer;
        }
-       spin_unlock_irq(&mdev->req_lock);
-
-       if (mdev->sync_conf.al_extents < 7)
-               mdev->sync_conf.al_extents = 127;
+       spin_unlock_irq(&mdev->tconn->req_lock);
 
  err:
        drbd_md_put_buffer(mdev);
@@ -4014,7 +3020,7 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev)
 #ifdef DEBUG
 void drbd_md_mark_dirty_(struct drbd_conf *mdev, unsigned int line, const char *func)
 {
-       if (!drbd_test_and_set_flag(mdev, MD_DIRTY)) {
+       if (!test_and_set_bit(MD_DIRTY, &mdev->flags)) {
                mod_timer(&mdev->md_sync_timer, jiffies + HZ);
                mdev->last_md_mark_dirty.line = line;
                mdev->last_md_mark_dirty.func = func;
@@ -4023,7 +3029,7 @@ void drbd_md_mark_dirty_(struct drbd_conf *mdev, unsigned int line, const char *
 #else
 void drbd_md_mark_dirty(struct drbd_conf *mdev)
 {
-       if (!drbd_test_and_set_flag(mdev, MD_DIRTY))
+       if (!test_and_set_bit(MD_DIRTY, &mdev->flags))
                mod_timer(&mdev->md_sync_timer, jiffies + 5*HZ);
 }
 #endif
@@ -4171,9 +3177,10 @@ int drbd_bmio_clear_n_write(struct drbd_conf *mdev)
        return rv;
 }
 
-static int w_bitmap_io(struct drbd_conf *mdev, struct drbd_work *w, int unused)
+static int w_bitmap_io(struct drbd_work *w, int unused)
 {
        struct bm_io_work *work = container_of(w, struct bm_io_work, w);
+       struct drbd_conf *mdev = w->mdev;
        int rv = -EIO;
 
        D_ASSERT(atomic_read(&mdev->ap_bio_cnt) == 0);
@@ -4185,18 +3192,17 @@ static int w_bitmap_io(struct drbd_conf *mdev, struct drbd_work *w, int unused)
                put_ldev(mdev);
        }
 
-       drbd_clear_flag(mdev, BITMAP_IO);
-       smp_mb__after_clear_bit();
+       clear_bit_unlock(BITMAP_IO, &mdev->flags);
        wake_up(&mdev->misc_wait);
 
        if (work->done)
                work->done(mdev, rv);
 
-       drbd_clear_flag(mdev, BITMAP_IO_QUEUED);
+       clear_bit(BITMAP_IO_QUEUED, &mdev->flags);
        work->why = NULL;
        work->flags = 0;
 
-       return 1;
+       return 0;
 }
 
 void drbd_ldev_destroy(struct drbd_conf *mdev)
@@ -4209,15 +3215,13 @@ void drbd_ldev_destroy(struct drbd_conf *mdev)
                drbd_free_bc(mdev->ldev);
                mdev->ldev = NULL;);
 
-       if (mdev->md_io_tmpp) {
-               __free_page(mdev->md_io_tmpp);
-               mdev->md_io_tmpp = NULL;
-       }
-       drbd_clear_flag(mdev, GO_DISKLESS);
+       clear_bit(GO_DISKLESS, &mdev->flags);
 }
 
-static int w_go_diskless(struct drbd_conf *mdev, struct drbd_work *w, int unused)
+static int w_go_diskless(struct drbd_work *w, int unused)
 {
+       struct drbd_conf *mdev = w->mdev;
+
        D_ASSERT(mdev->state.disk == D_FAILED);
        /* we cannot assert local_cnt == 0 here, as get_ldev_if_state will
         * inc/dec it frequently. Once we are D_DISKLESS, no one will touch
@@ -4232,11 +3236,15 @@ static int w_go_diskless(struct drbd_conf *mdev, struct drbd_work *w, int unused
         * (Do we want a specific meta data flag for this?)
         *
         * If that does not make it to stable storage either,
-        * we cannot do anything about that anymore.  */
-       if (mdev->bitmap) {
+        * we cannot do anything about that anymore.
+        *
+        * We still need to check if both bitmap and ldev are present, we may
+        * end up here after a failed attach, before ldev was even assigned.
+        */
+       if (mdev->bitmap && mdev->ldev) {
                if (drbd_bitmap_io_from_worker(mdev, drbd_bm_write,
                                        "detach", BM_LOCKED_MASK)) {
-                       if (drbd_test_flag(mdev, WAS_READ_ERROR)) {
+                       if (test_bit(WAS_READ_ERROR, &mdev->flags)) {
                                drbd_md_set_flag(mdev, MDF_FULL_SYNC);
                                drbd_md_sync(mdev);
                        }
@@ -4244,14 +3252,14 @@ static int w_go_diskless(struct drbd_conf *mdev, struct drbd_work *w, int unused
        }
 
        drbd_force_state(mdev, NS(disk, D_DISKLESS));
-       return 1;
+       return 0;
 }
 
 void drbd_go_diskless(struct drbd_conf *mdev)
 {
        D_ASSERT(mdev->state.disk == D_FAILED);
-       if (!drbd_test_and_set_flag(mdev, GO_DISKLESS))
-               drbd_queue_work(&mdev->data.work, &mdev->go_diskless);
+       if (!test_and_set_bit(GO_DISKLESS, &mdev->flags))
+               drbd_queue_work(&mdev->tconn->sender_work, &mdev->go_diskless);
 }
 
 /**
@@ -4271,10 +3279,10 @@ void drbd_queue_bitmap_io(struct drbd_conf *mdev,
                          void (*done)(struct drbd_conf *, int),
                          char *why, enum bm_flag flags)
 {
-       D_ASSERT(current == mdev->worker.task);
+       D_ASSERT(current == mdev->tconn->worker.task);
 
-       D_ASSERT(!drbd_test_flag(mdev, BITMAP_IO_QUEUED));
-       D_ASSERT(!drbd_test_flag(mdev, BITMAP_IO));
+       D_ASSERT(!test_bit(BITMAP_IO_QUEUED, &mdev->flags));
+       D_ASSERT(!test_bit(BITMAP_IO, &mdev->flags));
        D_ASSERT(list_empty(&mdev->bm_io_work.w.list));
        if (mdev->bm_io_work.why)
                dev_err(DEV, "FIXME going to queue '%s' but '%s' still pending?\n",
@@ -4285,13 +3293,13 @@ void drbd_queue_bitmap_io(struct drbd_conf *mdev,
        mdev->bm_io_work.why = why;
        mdev->bm_io_work.flags = flags;
 
-       spin_lock_irq(&mdev->req_lock);
-       drbd_set_flag(mdev, BITMAP_IO);
+       spin_lock_irq(&mdev->tconn->req_lock);
+       set_bit(BITMAP_IO, &mdev->flags);
        if (atomic_read(&mdev->ap_bio_cnt) == 0) {
-               if (!drbd_test_and_set_flag(mdev, BITMAP_IO_QUEUED))
-                       drbd_queue_work(&mdev->data.work, &mdev->bm_io_work.w);
+               if (!test_and_set_bit(BITMAP_IO_QUEUED, &mdev->flags))
+                       drbd_queue_work(&mdev->tconn->sender_work, &mdev->bm_io_work.w);
        }
-       spin_unlock_irq(&mdev->req_lock);
+       spin_unlock_irq(&mdev->tconn->req_lock);
 }
 
 /**
@@ -4308,7 +3316,7 @@ int drbd_bitmap_io(struct drbd_conf *mdev, int (*io_fn)(struct drbd_conf *),
 {
        int rv;
 
-       D_ASSERT(current != mdev->worker.task);
+       D_ASSERT(current != mdev->tconn->worker.task);
 
        if ((flags & BM_LOCKED_SET_ALLOWED) == 0)
                drbd_suspend_io(mdev);
@@ -4347,18 +3355,127 @@ static void md_sync_timer_fn(unsigned long data)
 {
        struct drbd_conf *mdev = (struct drbd_conf *) data;
 
-       drbd_queue_work_front(&mdev->data.work, &mdev->md_sync_work);
+       /* must not double-queue! */
+       if (list_empty(&mdev->md_sync_work.list))
+               drbd_queue_work_front(&mdev->tconn->sender_work, &mdev->md_sync_work);
 }
 
-static int w_md_sync(struct drbd_conf *mdev, struct drbd_work *w, int unused)
+static int w_md_sync(struct drbd_work *w, int unused)
 {
+       struct drbd_conf *mdev = w->mdev;
+
        dev_warn(DEV, "md_sync_timer expired! Worker calls drbd_md_sync().\n");
 #ifdef DEBUG
        dev_warn(DEV, "last md_mark_dirty: %s:%u\n",
                mdev->last_md_mark_dirty.func, mdev->last_md_mark_dirty.line);
 #endif
        drbd_md_sync(mdev);
-       return 1;
+       return 0;
+}
+
+const char *cmdname(enum drbd_packet cmd)
+{
+       /* THINK may need to become several global tables
+        * when we want to support more than
+        * one PRO_VERSION */
+       static const char *cmdnames[] = {
+               [P_DATA]                = "Data",
+               [P_DATA_REPLY]          = "DataReply",
+               [P_RS_DATA_REPLY]       = "RSDataReply",
+               [P_BARRIER]             = "Barrier",
+               [P_BITMAP]              = "ReportBitMap",
+               [P_BECOME_SYNC_TARGET]  = "BecomeSyncTarget",
+               [P_BECOME_SYNC_SOURCE]  = "BecomeSyncSource",
+               [P_UNPLUG_REMOTE]       = "UnplugRemote",
+               [P_DATA_REQUEST]        = "DataRequest",
+               [P_RS_DATA_REQUEST]     = "RSDataRequest",
+               [P_SYNC_PARAM]          = "SyncParam",
+               [P_SYNC_PARAM89]        = "SyncParam89",
+               [P_PROTOCOL]            = "ReportProtocol",
+               [P_UUIDS]               = "ReportUUIDs",
+               [P_SIZES]               = "ReportSizes",
+               [P_STATE]               = "ReportState",
+               [P_SYNC_UUID]           = "ReportSyncUUID",
+               [P_AUTH_CHALLENGE]      = "AuthChallenge",
+               [P_AUTH_RESPONSE]       = "AuthResponse",
+               [P_PING]                = "Ping",
+               [P_PING_ACK]            = "PingAck",
+               [P_RECV_ACK]            = "RecvAck",
+               [P_WRITE_ACK]           = "WriteAck",
+               [P_RS_WRITE_ACK]        = "RSWriteAck",
+               [P_SUPERSEDED]          = "Superseded",
+               [P_NEG_ACK]             = "NegAck",
+               [P_NEG_DREPLY]          = "NegDReply",
+               [P_NEG_RS_DREPLY]       = "NegRSDReply",
+               [P_BARRIER_ACK]         = "BarrierAck",
+               [P_STATE_CHG_REQ]       = "StateChgRequest",
+               [P_STATE_CHG_REPLY]     = "StateChgReply",
+               [P_OV_REQUEST]          = "OVRequest",
+               [P_OV_REPLY]            = "OVReply",
+               [P_OV_RESULT]           = "OVResult",
+               [P_CSUM_RS_REQUEST]     = "CsumRSRequest",
+               [P_RS_IS_IN_SYNC]       = "CsumRSIsInSync",
+               [P_COMPRESSED_BITMAP]   = "CBitmap",
+               [P_DELAY_PROBE]         = "DelayProbe",
+               [P_OUT_OF_SYNC]         = "OutOfSync",
+               [P_RETRY_WRITE]         = "RetryWrite",
+               [P_RS_CANCEL]           = "RSCancel",
+               [P_CONN_ST_CHG_REQ]     = "conn_st_chg_req",
+               [P_CONN_ST_CHG_REPLY]   = "conn_st_chg_reply",
+               [P_RETRY_WRITE]         = "retry_write",
+               [P_PROTOCOL_UPDATE]     = "protocol_update",
+
+               /* enum drbd_packet, but not commands - obsoleted flags:
+                *      P_MAY_IGNORE
+                *      P_MAX_OPT_CMD
+                */
+       };
+
+       /* too big for the array: 0xfffX */
+       if (cmd == P_INITIAL_META)
+               return "InitialMeta";
+       if (cmd == P_INITIAL_DATA)
+               return "InitialData";
+       if (cmd == P_CONNECTION_FEATURES)
+               return "ConnectionFeatures";
+       if (cmd >= ARRAY_SIZE(cmdnames))
+               return "Unknown";
+       return cmdnames[cmd];
+}
+
+/**
+ * drbd_wait_misc  -  wait for a request to make progress
+ * @mdev:      device associated with the request
+ * @i:         the struct drbd_interval embedded in struct drbd_request or
+ *             struct drbd_peer_request
+ */
+int drbd_wait_misc(struct drbd_conf *mdev, struct drbd_interval *i)
+{
+       struct net_conf *nc;
+       DEFINE_WAIT(wait);
+       long timeout;
+
+       rcu_read_lock();
+       nc = rcu_dereference(mdev->tconn->net_conf);
+       if (!nc) {
+               rcu_read_unlock();
+               return -ETIMEDOUT;
+       }
+       timeout = nc->ko_count ? nc->timeout * HZ / 10 * nc->ko_count : MAX_SCHEDULE_TIMEOUT;
+       rcu_read_unlock();
+
+       /* Indicate to wake up mdev->misc_wait on progress.  */
+       i->waiting = true;
+       prepare_to_wait(&mdev->misc_wait, &wait, TASK_INTERRUPTIBLE);
+       spin_unlock_irq(&mdev->tconn->req_lock);
+       timeout = schedule_timeout(timeout);
+       finish_wait(&mdev->misc_wait, &wait);
+       spin_lock_irq(&mdev->tconn->req_lock);
+       if (!timeout || mdev->state.conn < C_CONNECTED)
+               return -ETIMEDOUT;
+       if (signal_pending(current))
+               return -ERESTARTSYS;
+       return 0;
 }
 
 #ifdef CONFIG_DRBD_FAULT_INJECTION