]> Pileus Git - ~andy/linux/blobdiff - drivers/block/rbd.c
rbd: support reading parent page data
[~andy/linux] / drivers / block / rbd.c
index c34f8716d1d2109f20e0fa639c2b48d8382db5e0..2a0e9b81be483e1d57ac3c3facc7a457b89be2df 100644 (file)
@@ -1,3 +1,4 @@
+
 /*
    rbd.c -- Export ceph rados objects as a Linux block device
 
 #include <linux/ceph/mon_client.h>
 #include <linux/ceph/decode.h>
 #include <linux/parser.h>
+#include <linux/bsearch.h>
 
 #include <linux/kernel.h>
 #include <linux/device.h>
 #include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/blkdev.h>
+#include <linux/slab.h>
 
 #include "rbd_types.h"
 
@@ -65,6 +68,8 @@
 
 #define RBD_SNAP_HEAD_NAME     "-"
 
+#define        BAD_SNAP_INDEX  U32_MAX         /* invalid index into snap array */
+
 /* This allows a single page to hold an image name sent by OSD */
 #define RBD_IMAGE_NAME_LEN_MAX (PAGE_SIZE - sizeof (__le32) - 1)
 #define RBD_IMAGE_ID_LEN_MAX   64
  * block device image metadata (in-memory version)
  */
 struct rbd_image_header {
-       /* These four fields never change for a given rbd image */
+       /* These six fields never change for a given rbd image */
        char *object_prefix;
-       u64 features;
        __u8 obj_order;
        __u8 crypt_type;
        __u8 comp_type;
+       u64 stripe_unit;
+       u64 stripe_count;
+       u64 features;           /* Might be changeable someday? */
 
        /* The remaining fields need to be updated occasionally */
        u64 image_size;
        struct ceph_snap_context *snapc;
-       char *snap_names;
-       u64 *snap_sizes;
-
-       u64 obj_version;
+       char *snap_names;       /* format 1 only */
+       u64 *snap_sizes;        /* format 1 only */
 };
 
 /*
@@ -138,13 +143,13 @@ struct rbd_image_header {
  */
 struct rbd_spec {
        u64             pool_id;
-       char            *pool_name;
+       const char      *pool_name;
 
-       char            *image_id;
-       char            *image_name;
+       const char      *image_id;
+       const char      *image_name;
 
        u64             snap_id;
-       char            *snap_name;
+       const char      *snap_name;
 
        struct kref     kref;
 };
@@ -223,7 +228,6 @@ struct rbd_obj_request {
        struct ceph_osd_request *osd_req;
 
        u64                     xferred;        /* bytes transferred */
-       u64                     version;
        int                     result;
 
        rbd_obj_callback_t      callback;
@@ -271,14 +275,6 @@ struct rbd_img_request {
 #define for_each_obj_request_safe(ireq, oreq, n) \
        list_for_each_entry_safe_reverse(oreq, n, &(ireq)->obj_requests, links)
 
-struct rbd_snap {
-       const char              *name;
-       u64                     size;
-       struct list_head        node;
-       u64                     id;
-       u64                     features;
-};
-
 struct rbd_mapping {
        u64                     size;
        u64                     features;
@@ -316,9 +312,6 @@ struct rbd_device {
        u64                     parent_overlap;
        struct rbd_device       *parent;
 
-       u64                     stripe_unit;
-       u64                     stripe_count;
-
        /* protects updating the header */
        struct rw_semaphore     header_rwsem;
 
@@ -326,9 +319,6 @@ struct rbd_device {
 
        struct list_head        node;
 
-       /* list of snapshots */
-       struct list_head        snaps;
-
        /* sysfs related */
        struct device           dev;
        unsigned long           open_count;     /* protected by lock */
@@ -354,18 +344,21 @@ static DEFINE_SPINLOCK(rbd_dev_list_lock);
 static LIST_HEAD(rbd_client_list);             /* clients */
 static DEFINE_SPINLOCK(rbd_client_list_lock);
 
-static int rbd_img_request_submit(struct rbd_img_request *img_request);
+/* Slab caches for frequently-allocated structures */
+
+static struct kmem_cache       *rbd_img_request_cache;
+static struct kmem_cache       *rbd_obj_request_cache;
+static struct kmem_cache       *rbd_segment_name_cache;
 
-static int rbd_dev_snaps_update(struct rbd_device *rbd_dev);
+static int rbd_img_request_submit(struct rbd_img_request *img_request);
 
-static void rbd_dev_release(struct device *dev);
-static void rbd_snap_destroy(struct rbd_snap *snap);
+static void rbd_dev_device_release(struct device *dev);
 
 static ssize_t rbd_add(struct bus_type *bus, const char *buf,
                       size_t count);
 static ssize_t rbd_remove(struct bus_type *bus, const char *buf,
                          size_t count);
-static int rbd_dev_probe(struct rbd_device *rbd_dev);
+static int rbd_dev_image_probe(struct rbd_device *rbd_dev, bool read_only);
 
 static struct bus_attribute rbd_bus_attrs[] = {
        __ATTR(add, S_IWUSR, NULL, rbd_add),
@@ -427,11 +420,20 @@ void rbd_warn(struct rbd_device *rbd_dev, const char *fmt, ...)
 #  define rbd_assert(expr)     ((void) 0)
 #endif /* !RBD_DEBUG */
 
-static void rbd_img_parent_read(struct rbd_obj_request *obj_request);
 static int rbd_img_obj_request_submit(struct rbd_obj_request *obj_request);
+static void rbd_img_parent_read(struct rbd_obj_request *obj_request);
+static void rbd_dev_remove_parent(struct rbd_device *rbd_dev);
 
-static int rbd_dev_refresh(struct rbd_device *rbd_dev, u64 *hver);
-static int rbd_dev_v2_refresh(struct rbd_device *rbd_dev, u64 *hver);
+static int rbd_dev_refresh(struct rbd_device *rbd_dev);
+static int rbd_dev_v2_header_onetime(struct rbd_device *rbd_dev);
+static int rbd_dev_v2_header_info(struct rbd_device *rbd_dev);
+static const char *rbd_dev_v2_snap_name(struct rbd_device *rbd_dev,
+                                       u64 snap_id);
+static int _rbd_dev_v2_snap_size(struct rbd_device *rbd_dev, u64 snap_id,
+                               u8 *order, u64 *snap_size);
+static int _rbd_dev_v2_snap_features(struct rbd_device *rbd_dev, u64 snap_id,
+               u64 *snap_features);
+static u64 rbd_snap_id_by_name(struct rbd_device *rbd_dev, const char *name);
 
 static int rbd_open(struct block_device *bdev, fmode_t mode)
 {
@@ -726,153 +728,271 @@ static bool rbd_dev_ondisk_valid(struct rbd_image_header_ondisk *ondisk)
 }
 
 /*
- * Create a new header structure, translate header format from the on-disk
- * header.
+ * Fill an rbd image header with information from the given format 1
+ * on-disk header.
  */
-static int rbd_header_from_disk(struct rbd_image_header *header,
+static int rbd_header_from_disk(struct rbd_device *rbd_dev,
                                 struct rbd_image_header_ondisk *ondisk)
 {
+       struct rbd_image_header *header = &rbd_dev->header;
+       bool first_time = header->object_prefix == NULL;
+       struct ceph_snap_context *snapc;
+       char *object_prefix = NULL;
+       char *snap_names = NULL;
+       u64 *snap_sizes = NULL;
        u32 snap_count;
-       size_t len;
        size_t size;
+       int ret = -ENOMEM;
        u32 i;
 
-       memset(header, 0, sizeof (*header));
+       /* Allocate this now to avoid having to handle failure below */
 
-       snap_count = le32_to_cpu(ondisk->snap_count);
+       if (first_time) {
+               size_t len;
 
-       len = strnlen(ondisk->object_prefix, sizeof (ondisk->object_prefix));
-       header->object_prefix = kmalloc(len + 1, GFP_KERNEL);
-       if (!header->object_prefix)
-               return -ENOMEM;
-       memcpy(header->object_prefix, ondisk->object_prefix, len);
-       header->object_prefix[len] = '\0';
+               len = strnlen(ondisk->object_prefix,
+                               sizeof (ondisk->object_prefix));
+               object_prefix = kmalloc(len + 1, GFP_KERNEL);
+               if (!object_prefix)
+                       return -ENOMEM;
+               memcpy(object_prefix, ondisk->object_prefix, len);
+               object_prefix[len] = '\0';
+       }
 
+       /* Allocate the snapshot context and fill it in */
+
+       snap_count = le32_to_cpu(ondisk->snap_count);
+       snapc = ceph_create_snap_context(snap_count, GFP_KERNEL);
+       if (!snapc)
+               goto out_err;
+       snapc->seq = le64_to_cpu(ondisk->snap_seq);
        if (snap_count) {
+               struct rbd_image_snap_ondisk *snaps;
                u64 snap_names_len = le64_to_cpu(ondisk->snap_names_len);
 
-               /* Save a copy of the snapshot names */
+               /* We'll keep a copy of the snapshot names... */
+
+               if (snap_names_len > (u64)SIZE_MAX)
+                       goto out_2big;
+               snap_names = kmalloc(snap_names_len, GFP_KERNEL);
+               if (!snap_names)
+                       goto out_err;
+
+               /* ...as well as the array of their sizes. */
 
-               if (snap_names_len > (u64) SIZE_MAX)
-                       return -EIO;
-               header->snap_names = kmalloc(snap_names_len, GFP_KERNEL);
-               if (!header->snap_names)
+               size = snap_count * sizeof (*header->snap_sizes);
+               snap_sizes = kmalloc(size, GFP_KERNEL);
+               if (!snap_sizes)
                        goto out_err;
+
                /*
-                * Note that rbd_dev_v1_header_read() guarantees
-                * the ondisk buffer we're working with has
+                * Copy the names, and fill in each snapshot's id
+                * and size.
+                *
+                * Note that rbd_dev_v1_header_info() guarantees the
+                * ondisk buffer we're working with has
                 * snap_names_len bytes beyond the end of the
                 * snapshot id array, this memcpy() is safe.
                 */
-               memcpy(header->snap_names, &ondisk->snaps[snap_count],
-                       snap_names_len);
+               memcpy(snap_names, &ondisk->snaps[snap_count], snap_names_len);
+               snaps = ondisk->snaps;
+               for (i = 0; i < snap_count; i++) {
+                       snapc->snaps[i] = le64_to_cpu(snaps[i].id);
+                       snap_sizes[i] = le64_to_cpu(snaps[i].image_size);
+               }
+       }
 
-               /* Record each snapshot's size */
+       /* We won't fail any more, fill in the header */
 
-               size = snap_count * sizeof (*header->snap_sizes);
-               header->snap_sizes = kmalloc(size, GFP_KERNEL);
-               if (!header->snap_sizes)
-                       goto out_err;
-               for (i = 0; i < snap_count; i++)
-                       header->snap_sizes[i] =
-                               le64_to_cpu(ondisk->snaps[i].image_size);
+       down_write(&rbd_dev->header_rwsem);
+       if (first_time) {
+               header->object_prefix = object_prefix;
+               header->obj_order = ondisk->options.order;
+               header->crypt_type = ondisk->options.crypt_type;
+               header->comp_type = ondisk->options.comp_type;
+               /* The rest aren't used for format 1 images */
+               header->stripe_unit = 0;
+               header->stripe_count = 0;
+               header->features = 0;
        } else {
-               WARN_ON(ondisk->snap_names_len);
-               header->snap_names = NULL;
-               header->snap_sizes = NULL;
+               ceph_put_snap_context(header->snapc);
+               kfree(header->snap_names);
+               kfree(header->snap_sizes);
        }
 
-       header->features = 0;   /* No features support in v1 images */
-       header->obj_order = ondisk->options.order;
-       header->crypt_type = ondisk->options.crypt_type;
-       header->comp_type = ondisk->options.comp_type;
-
-       /* Allocate and fill in the snapshot context */
+       /* The remaining fields always get updated (when we refresh) */
 
        header->image_size = le64_to_cpu(ondisk->image_size);
-       size = sizeof (struct ceph_snap_context);
-       size += snap_count * sizeof (header->snapc->snaps[0]);
-       header->snapc = kzalloc(size, GFP_KERNEL);
-       if (!header->snapc)
-               goto out_err;
+       header->snapc = snapc;
+       header->snap_names = snap_names;
+       header->snap_sizes = snap_sizes;
 
-       atomic_set(&header->snapc->nref, 1);
-       header->snapc->seq = le64_to_cpu(ondisk->snap_seq);
-       header->snapc->num_snaps = snap_count;
-       for (i = 0; i < snap_count; i++)
-               header->snapc->snaps[i] =
-                       le64_to_cpu(ondisk->snaps[i].id);
+       /* Make sure mapping size is consistent with header info */
 
-       return 0;
+       if (rbd_dev->spec->snap_id == CEPH_NOSNAP || first_time)
+               if (rbd_dev->mapping.size != header->image_size)
+                       rbd_dev->mapping.size = header->image_size;
+
+       up_write(&rbd_dev->header_rwsem);
 
+       return 0;
+out_2big:
+       ret = -EIO;
 out_err:
-       kfree(header->snap_sizes);
-       header->snap_sizes = NULL;
-       kfree(header->snap_names);
-       header->snap_names = NULL;
-       kfree(header->object_prefix);
-       header->object_prefix = NULL;
+       kfree(snap_sizes);
+       kfree(snap_names);
+       ceph_put_snap_context(snapc);
+       kfree(object_prefix);
 
-       return -ENOMEM;
+       return ret;
 }
 
-static const char *rbd_snap_name(struct rbd_device *rbd_dev, u64 snap_id)
+static const char *_rbd_dev_v1_snap_name(struct rbd_device *rbd_dev, u32 which)
+{
+       const char *snap_name;
+
+       rbd_assert(which < rbd_dev->header.snapc->num_snaps);
+
+       /* Skip over names until we find the one we are looking for */
+
+       snap_name = rbd_dev->header.snap_names;
+       while (which--)
+               snap_name += strlen(snap_name) + 1;
+
+       return kstrdup(snap_name, GFP_KERNEL);
+}
+
+/*
+ * Snapshot id comparison function for use with qsort()/bsearch().
+ * Note that result is for snapshots in *descending* order.
+ */
+static int snapid_compare_reverse(const void *s1, const void *s2)
 {
-       struct rbd_snap *snap;
+       u64 snap_id1 = *(u64 *)s1;
+       u64 snap_id2 = *(u64 *)s2;
 
+       if (snap_id1 < snap_id2)
+               return 1;
+       return snap_id1 == snap_id2 ? 0 : -1;
+}
+
+/*
+ * Search a snapshot context to see if the given snapshot id is
+ * present.
+ *
+ * Returns the position of the snapshot id in the array if it's found,
+ * or BAD_SNAP_INDEX otherwise.
+ *
+ * Note: The snapshot array is in kept sorted (by the osd) in
+ * reverse order, highest snapshot id first.
+ */
+static u32 rbd_dev_snap_index(struct rbd_device *rbd_dev, u64 snap_id)
+{
+       struct ceph_snap_context *snapc = rbd_dev->header.snapc;
+       u64 *found;
+
+       found = bsearch(&snap_id, &snapc->snaps, snapc->num_snaps,
+                               sizeof (snap_id), snapid_compare_reverse);
+
+       return found ? (u32)(found - &snapc->snaps[0]) : BAD_SNAP_INDEX;
+}
+
+static const char *rbd_dev_v1_snap_name(struct rbd_device *rbd_dev,
+                                       u64 snap_id)
+{
+       u32 which;
+
+       which = rbd_dev_snap_index(rbd_dev, snap_id);
+       if (which == BAD_SNAP_INDEX)
+               return NULL;
+
+       return _rbd_dev_v1_snap_name(rbd_dev, which);
+}
+
+static const char *rbd_snap_name(struct rbd_device *rbd_dev, u64 snap_id)
+{
        if (snap_id == CEPH_NOSNAP)
                return RBD_SNAP_HEAD_NAME;
 
-       list_for_each_entry(snap, &rbd_dev->snaps, node)
-               if (snap_id == snap->id)
-                       return snap->name;
+       rbd_assert(rbd_image_format_valid(rbd_dev->image_format));
+       if (rbd_dev->image_format == 1)
+               return rbd_dev_v1_snap_name(rbd_dev, snap_id);
 
-       return NULL;
+       return rbd_dev_v2_snap_name(rbd_dev, snap_id);
 }
 
-static struct rbd_snap *snap_by_name(struct rbd_device *rbd_dev,
-                                       const char *snap_name)
+static int rbd_snap_size(struct rbd_device *rbd_dev, u64 snap_id,
+                               u64 *snap_size)
 {
-       struct rbd_snap *snap;
+       rbd_assert(rbd_image_format_valid(rbd_dev->image_format));
+       if (snap_id == CEPH_NOSNAP) {
+               *snap_size = rbd_dev->header.image_size;
+       } else if (rbd_dev->image_format == 1) {
+               u32 which;
 
-       list_for_each_entry(snap, &rbd_dev->snaps, node)
-               if (!strcmp(snap_name, snap->name))
-                       return snap;
+               which = rbd_dev_snap_index(rbd_dev, snap_id);
+               if (which == BAD_SNAP_INDEX)
+                       return -ENOENT;
 
-       return NULL;
+               *snap_size = rbd_dev->header.snap_sizes[which];
+       } else {
+               u64 size = 0;
+               int ret;
+
+               ret = _rbd_dev_v2_snap_size(rbd_dev, snap_id, NULL, &size);
+               if (ret)
+                       return ret;
+
+               *snap_size = size;
+       }
+       return 0;
 }
 
-static int rbd_dev_set_mapping(struct rbd_device *rbd_dev)
+static int rbd_snap_features(struct rbd_device *rbd_dev, u64 snap_id,
+                       u64 *snap_features)
 {
-       if (!memcmp(rbd_dev->spec->snap_name, RBD_SNAP_HEAD_NAME,
-                   sizeof (RBD_SNAP_HEAD_NAME))) {
-               rbd_dev->mapping.size = rbd_dev->header.image_size;
-               rbd_dev->mapping.features = rbd_dev->header.features;
+       rbd_assert(rbd_image_format_valid(rbd_dev->image_format));
+       if (snap_id == CEPH_NOSNAP) {
+               *snap_features = rbd_dev->header.features;
+       } else if (rbd_dev->image_format == 1) {
+               *snap_features = 0;     /* No features for format 1 */
        } else {
-               struct rbd_snap *snap;
+               u64 features = 0;
+               int ret;
 
-               snap = snap_by_name(rbd_dev, rbd_dev->spec->snap_name);
-               if (!snap)
-                       return -ENOENT;
-               rbd_dev->mapping.size = snap->size;
-               rbd_dev->mapping.features = snap->features;
-               rbd_dev->mapping.read_only = true;
+               ret = _rbd_dev_v2_snap_features(rbd_dev, snap_id, &features);
+               if (ret)
+                       return ret;
+
+               *snap_features = features;
        }
-       set_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);
+       return 0;
+}
+
+static int rbd_dev_mapping_set(struct rbd_device *rbd_dev)
+{
+       u64 snap_id = rbd_dev->spec->snap_id;
+       u64 size = 0;
+       u64 features = 0;
+       int ret;
+
+       ret = rbd_snap_size(rbd_dev, snap_id, &size);
+       if (ret)
+               return ret;
+       ret = rbd_snap_features(rbd_dev, snap_id, &features);
+       if (ret)
+               return ret;
+
+       rbd_dev->mapping.size = size;
+       rbd_dev->mapping.features = features;
 
        return 0;
 }
 
-static void rbd_header_free(struct rbd_image_header *header)
+static void rbd_dev_mapping_clear(struct rbd_device *rbd_dev)
 {
-       kfree(header->object_prefix);
-       header->object_prefix = NULL;
-       kfree(header->snap_sizes);
-       header->snap_sizes = NULL;
-       kfree(header->snap_names);
-       header->snap_names = NULL;
-       ceph_put_snap_context(header->snapc);
-       header->snapc = NULL;
+       rbd_dev->mapping.size = 0;
+       rbd_dev->mapping.features = 0;
 }
 
 static const char *rbd_segment_name(struct rbd_device *rbd_dev, u64 offset)
@@ -881,7 +1001,7 @@ static const char *rbd_segment_name(struct rbd_device *rbd_dev, u64 offset)
        u64 segment;
        int ret;
 
-       name = kmalloc(MAX_OBJ_NAME_SIZE + 1, GFP_NOIO);
+       name = kmem_cache_alloc(rbd_segment_name_cache, GFP_NOIO);
        if (!name)
                return NULL;
        segment = offset >> rbd_dev->header.obj_order;
@@ -897,6 +1017,13 @@ static const char *rbd_segment_name(struct rbd_device *rbd_dev, u64 offset)
        return name;
 }
 
+static void rbd_segment_name_free(const char *name)
+{
+       /* The explicit cast here is needed to drop the const qualifier */
+
+       kmem_cache_free(rbd_segment_name_cache, (void *)name);
+}
+
 static u64 rbd_segment_offset(struct rbd_device *rbd_dev, u64 offset)
 {
        u64 segment_size = (u64) 1 << rbd_dev->header.obj_order;
@@ -1491,7 +1618,6 @@ static void rbd_osd_req_callback(struct ceph_osd_request *osd_req,
 
        if (osd_req->r_result < 0)
                obj_request->result = osd_req->r_result;
-       obj_request->version = le64_to_cpu(osd_req->r_reassert_version.version);
 
        BUG_ON(osd_req->r_num_ops > 2);
 
@@ -1656,11 +1782,16 @@ static struct rbd_obj_request *rbd_obj_request_create(const char *object_name,
        rbd_assert(obj_request_type_valid(type));
 
        size = strlen(object_name) + 1;
-       obj_request = kzalloc(sizeof (*obj_request) + size, GFP_KERNEL);
-       if (!obj_request)
+       name = kmalloc(size, GFP_KERNEL);
+       if (!name)
                return NULL;
 
-       name = (char *)(obj_request + 1);
+       obj_request = kmem_cache_zalloc(rbd_obj_request_cache, GFP_KERNEL);
+       if (!obj_request) {
+               kfree(name);
+               return NULL;
+       }
+
        obj_request->object_name = memcpy(name, object_name, size);
        obj_request->offset = offset;
        obj_request->length = length;
@@ -1706,7 +1837,9 @@ static void rbd_obj_request_destroy(struct kref *kref)
                break;
        }
 
-       kfree(obj_request);
+       kfree(obj_request->object_name);
+       obj_request->object_name = NULL;
+       kmem_cache_free(rbd_obj_request_cache, obj_request);
 }
 
 /*
@@ -1721,21 +1854,15 @@ static struct rbd_img_request *rbd_img_request_create(
                                        bool child_request)
 {
        struct rbd_img_request *img_request;
-       struct ceph_snap_context *snapc = NULL;
 
-       img_request = kmalloc(sizeof (*img_request), GFP_ATOMIC);
+       img_request = kmem_cache_alloc(rbd_img_request_cache, GFP_ATOMIC);
        if (!img_request)
                return NULL;
 
        if (write_request) {
                down_read(&rbd_dev->header_rwsem);
-               snapc = ceph_get_snap_context(rbd_dev->header.snapc);
+               ceph_get_snap_context(rbd_dev->header.snapc);
                up_read(&rbd_dev->header_rwsem);
-               if (WARN_ON(!snapc)) {
-                       kfree(img_request);
-                       return NULL;    /* Shouldn't happen */
-               }
-
        }
 
        img_request->rq = NULL;
@@ -1745,7 +1872,7 @@ static struct rbd_img_request *rbd_img_request_create(
        img_request->flags = 0;
        if (write_request) {
                img_request_write_set(img_request);
-               img_request->snapc = snapc;
+               img_request->snapc = rbd_dev->header.snapc;
        } else {
                img_request->snap_id = rbd_dev->spec->snap_id;
        }
@@ -1791,7 +1918,7 @@ static void rbd_img_request_destroy(struct kref *kref)
        if (img_request_child_test(img_request))
                rbd_obj_request_put(img_request->obj_request);
 
-       kfree(img_request);
+       kmem_cache_free(rbd_img_request_cache, img_request);
 }
 
 static bool rbd_img_obj_end_request(struct rbd_obj_request *obj_request)
@@ -1929,7 +2056,8 @@ static int rbd_img_request_fill(struct rbd_img_request *img_request,
                length = rbd_segment_length(rbd_dev, img_offset, resid);
                obj_request = rbd_obj_request_create(object_name,
                                                offset, length, type);
-               kfree(object_name);     /* object request has its own copy */
+               /* object request has its own copy of the object name */
+               rbd_segment_name_free(object_name);
                if (!obj_request)
                        goto out_unwind;
 
@@ -2058,13 +2186,13 @@ rbd_img_obj_parent_read_full_callback(struct rbd_img_request *img_request)
        result = img_request->result;
        obj_size = img_request->length;
        xferred = img_request->xferred;
+       rbd_img_request_put(img_request);
 
-       rbd_dev = img_request->rbd_dev;
+       rbd_assert(orig_request->img_request);
+       rbd_dev = orig_request->img_request->rbd_dev;
        rbd_assert(rbd_dev);
        rbd_assert(obj_size == (u64)1 << rbd_dev->header.obj_order);
 
-       rbd_img_request_put(img_request);
-
        if (result)
                goto out_err;
 
@@ -2432,6 +2560,7 @@ static void rbd_img_parent_read_callback(struct rbd_img_request *img_request)
                obj_request->xferred = img_request->xferred;
        }
 out:
+       rbd_img_request_put(img_request);
        rbd_img_obj_request_read_callback(obj_request);
        rbd_obj_request_complete(obj_request);
 }
@@ -2445,7 +2574,7 @@ static void rbd_img_parent_read(struct rbd_obj_request *obj_request)
        rbd_assert(obj_request_img_data_test(obj_request));
        rbd_assert(obj_request->img_request != NULL);
        rbd_assert(obj_request->result == (s32) -ENOENT);
-       rbd_assert(obj_request->type == OBJ_REQUEST_BIO);
+       rbd_assert(obj_request_type_valid(obj_request->type));
 
        rbd_dev = obj_request->img_request->rbd_dev;
        rbd_assert(rbd_dev->parent != NULL);
@@ -2461,8 +2590,12 @@ static void rbd_img_parent_read(struct rbd_obj_request *obj_request)
        rbd_obj_request_get(obj_request);
        img_request->obj_request = obj_request;
 
-       result = rbd_img_request_fill(img_request, OBJ_REQUEST_BIO,
-                                       obj_request->bio_list);
+       if (obj_request->type == OBJ_REQUEST_BIO)
+               result = rbd_img_request_fill(img_request, OBJ_REQUEST_BIO,
+                                               obj_request->bio_list);
+       else
+               result = rbd_img_request_fill(img_request, OBJ_REQUEST_PAGES,
+                                               obj_request->pages);
        if (result)
                goto out_err;
 
@@ -2480,8 +2613,7 @@ out_err:
        obj_request_done_set(obj_request);
 }
 
-static int rbd_obj_notify_ack(struct rbd_device *rbd_dev,
-                                  u64 ver, u64 notify_id)
+static int rbd_obj_notify_ack(struct rbd_device *rbd_dev, u64 notify_id)
 {
        struct rbd_obj_request *obj_request;
        struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
@@ -2499,7 +2631,7 @@ static int rbd_obj_notify_ack(struct rbd_device *rbd_dev,
        obj_request->callback = rbd_obj_request_put;
 
        osd_req_op_watch_init(obj_request->osd_req, 0, CEPH_OSD_OP_NOTIFY_ACK,
-                                       notify_id, ver, 0);
+                                       notify_id, 0, 0);
        rbd_osd_req_format_read(obj_request);
 
        ret = rbd_obj_request_submit(osdc, obj_request);
@@ -2513,17 +2645,19 @@ out:
 static void rbd_watch_cb(u64 ver, u64 notify_id, u8 opcode, void *data)
 {
        struct rbd_device *rbd_dev = (struct rbd_device *)data;
-       u64 hver;
+       int ret;
 
        if (!rbd_dev)
                return;
 
        dout("%s: \"%s\" notify_id %llu opcode %u\n", __func__,
-               rbd_dev->header_name, (unsigned long long) notify_id,
-               (unsigned int) opcode);
-       (void)rbd_dev_refresh(rbd_dev, &hver);
+               rbd_dev->header_name, (unsigned long long)notify_id,
+               (unsigned int)opcode);
+       ret = rbd_dev_refresh(rbd_dev);
+       if (ret)
+               rbd_warn(rbd_dev, ": header refresh error (%d)\n", ret);
 
-       rbd_obj_notify_ack(rbd_dev, hver, notify_id);
+       rbd_obj_notify_ack(rbd_dev, notify_id);
 }
 
 /*
@@ -2564,8 +2698,7 @@ static int rbd_dev_header_watch_sync(struct rbd_device *rbd_dev, int start)
                                        rbd_dev->watch_request->osd_req);
 
        osd_req_op_watch_init(obj_request->osd_req, 0, CEPH_OSD_OP_WATCH,
-                               rbd_dev->watch_event->cookie,
-                               rbd_dev->header.obj_version, start);
+                               rbd_dev->watch_event->cookie, 0, start);
        rbd_osd_req_format_write(obj_request);
 
        ret = rbd_obj_request_submit(osdc, obj_request);
@@ -2617,8 +2750,7 @@ static int rbd_obj_method_sync(struct rbd_device *rbd_dev,
                             const void *outbound,
                             size_t outbound_size,
                             void *inbound,
-                            size_t inbound_size,
-                            u64 *version)
+                            size_t inbound_size)
 {
        struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
        struct rbd_obj_request *obj_request;
@@ -2684,8 +2816,6 @@ static int rbd_obj_method_sync(struct rbd_device *rbd_dev,
        rbd_assert(obj_request->xferred < (u64)INT_MAX);
        ret = (int)obj_request->xferred;
        ceph_copy_from_page_vector(pages, inbound, 0, obj_request->xferred);
-       if (version)
-               *version = obj_request->version;
 out:
        if (obj_request)
                rbd_obj_request_put(obj_request);
@@ -2755,8 +2885,18 @@ static void rbd_request_fn(struct request_queue *q)
                }
 
                result = -EINVAL;
-               if (WARN_ON(offset && length > U64_MAX - offset + 1))
+               if (offset && length > U64_MAX - offset + 1) {
+                       rbd_warn(rbd_dev, "bad request range (%llu~%llu)\n",
+                               offset, length);
                        goto end_request;       /* Shouldn't happen */
+               }
+
+               result = -EIO;
+               if (offset + length > rbd_dev->mapping.size) {
+                       rbd_warn(rbd_dev, "beyond EOD (%llu~%llu > %llu)\n",
+                               offset, length, rbd_dev->mapping.size);
+                       goto end_request;
+               }
 
                result = -ENOMEM;
                img_request = rbd_img_request_create(rbd_dev, offset, length,
@@ -2848,8 +2988,7 @@ static void rbd_free_disk(struct rbd_device *rbd_dev)
 
 static int rbd_obj_read_sync(struct rbd_device *rbd_dev,
                                const char *object_name,
-                               u64 offset, u64 length,
-                               void *buf, u64 *version)
+                               u64 offset, u64 length, void *buf)
 
 {
        struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
@@ -2900,10 +3039,8 @@ static int rbd_obj_read_sync(struct rbd_device *rbd_dev,
        rbd_assert(obj_request->xferred <= (u64) SIZE_MAX);
        size = (size_t) obj_request->xferred;
        ceph_copy_from_page_vector(pages, buf, 0, size);
-       rbd_assert(size <= (size_t) INT_MAX);
-       ret = (int) size;
-       if (version)
-               *version = obj_request->version;
+       rbd_assert(size <= (size_t)INT_MAX);
+       ret = (int)size;
 out:
        if (obj_request)
                rbd_obj_request_put(obj_request);
@@ -2914,17 +3051,11 @@ out:
 }
 
 /*
- * Read the complete header for the given rbd device.
- *
- * Returns a pointer to a dynamically-allocated buffer containing
- * the complete and validated header.  Caller can pass the address
- * of a variable that will be filled in with the version of the
- * header object at the time it was read.
- *
- * Returns a pointer-coded errno if a failure occurs.
+ * Read the complete header for the given rbd device.  On successful
+ * return, the rbd_dev->header field will contain up-to-date
+ * information about the image.
  */
-static struct rbd_image_header_ondisk *
-rbd_dev_v1_header_read(struct rbd_device *rbd_dev, u64 *version)
+static int rbd_dev_v1_header_info(struct rbd_device *rbd_dev)
 {
        struct rbd_image_header_ondisk *ondisk = NULL;
        u32 snap_count = 0;
@@ -2949,22 +3080,22 @@ rbd_dev_v1_header_read(struct rbd_device *rbd_dev, u64 *version)
                size += names_size;
                ondisk = kmalloc(size, GFP_KERNEL);
                if (!ondisk)
-                       return ERR_PTR(-ENOMEM);
+                       return -ENOMEM;
 
                ret = rbd_obj_read_sync(rbd_dev, rbd_dev->header_name,
-                                      0, size, ondisk, version);
+                                      0, size, ondisk);
                if (ret < 0)
-                       goto out_err;
-               if (WARN_ON((size_t) ret < size)) {
+                       goto out;
+               if ((size_t)ret < size) {
                        ret = -ENXIO;
                        rbd_warn(rbd_dev, "short header read (want %zd got %d)",
                                size, ret);
-                       goto out_err;
+                       goto out;
                }
                if (!rbd_dev_ondisk_valid(ondisk)) {
                        ret = -ENXIO;
                        rbd_warn(rbd_dev, "invalid header");
-                       goto out_err;
+                       goto out;
                }
 
                names_size = le64_to_cpu(ondisk->snap_names_len);
@@ -2972,116 +3103,57 @@ rbd_dev_v1_header_read(struct rbd_device *rbd_dev, u64 *version)
                snap_count = le32_to_cpu(ondisk->snap_count);
        } while (snap_count != want_count);
 
-       return ondisk;
-
-out_err:
-       kfree(ondisk);
-
-       return ERR_PTR(ret);
-}
-
-/*
- * reload the ondisk the header
- */
-static int rbd_read_header(struct rbd_device *rbd_dev,
-                          struct rbd_image_header *header)
-{
-       struct rbd_image_header_ondisk *ondisk;
-       u64 ver = 0;
-       int ret;
-
-       ondisk = rbd_dev_v1_header_read(rbd_dev, &ver);
-       if (IS_ERR(ondisk))
-               return PTR_ERR(ondisk);
-       ret = rbd_header_from_disk(header, ondisk);
-       if (ret >= 0)
-               header->obj_version = ver;
+       ret = rbd_header_from_disk(rbd_dev, ondisk);
+out:
        kfree(ondisk);
 
        return ret;
 }
 
-static void rbd_remove_all_snaps(struct rbd_device *rbd_dev)
-{
-       struct rbd_snap *snap;
-       struct rbd_snap *next;
-
-       list_for_each_entry_safe(snap, next, &rbd_dev->snaps, node) {
-               list_del(&snap->node);
-               rbd_snap_destroy(snap);
-       }
-}
-
-static void rbd_update_mapping_size(struct rbd_device *rbd_dev)
-{
-       sector_t size;
-
-       if (rbd_dev->spec->snap_id != CEPH_NOSNAP)
-               return;
-
-       size = (sector_t) rbd_dev->header.image_size / SECTOR_SIZE;
-       dout("setting size to %llu sectors", (unsigned long long) size);
-       rbd_dev->mapping.size = (u64) size;
-       set_capacity(rbd_dev->disk, size);
-}
-
 /*
- * only read the first part of the ondisk header, without the snaps info
+ * Clear the rbd device's EXISTS flag if the snapshot it's mapped to
+ * has disappeared from the (just updated) snapshot context.
  */
-static int rbd_dev_v1_refresh(struct rbd_device *rbd_dev, u64 *hver)
+static void rbd_exists_validate(struct rbd_device *rbd_dev)
 {
-       int ret;
-       struct rbd_image_header h;
-
-       ret = rbd_read_header(rbd_dev, &h);
-       if (ret < 0)
-               return ret;
-
-       down_write(&rbd_dev->header_rwsem);
-
-       /* Update image size, and check for resize of mapped image */
-       rbd_dev->header.image_size = h.image_size;
-       rbd_update_mapping_size(rbd_dev);
-
-       /* rbd_dev->header.object_prefix shouldn't change */
-       kfree(rbd_dev->header.snap_sizes);
-       kfree(rbd_dev->header.snap_names);
-       /* osd requests may still refer to snapc */
-       ceph_put_snap_context(rbd_dev->header.snapc);
-
-       if (hver)
-               *hver = h.obj_version;
-       rbd_dev->header.obj_version = h.obj_version;
-       rbd_dev->header.image_size = h.image_size;
-       rbd_dev->header.snapc = h.snapc;
-       rbd_dev->header.snap_names = h.snap_names;
-       rbd_dev->header.snap_sizes = h.snap_sizes;
-       /* Free the extra copy of the object prefix */
-       WARN_ON(strcmp(rbd_dev->header.object_prefix, h.object_prefix));
-       kfree(h.object_prefix);
+       u64 snap_id;
 
-       ret = rbd_dev_snaps_update(rbd_dev);
+       if (!test_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags))
+               return;
 
-       up_write(&rbd_dev->header_rwsem);
+       snap_id = rbd_dev->spec->snap_id;
+       if (snap_id == CEPH_NOSNAP)
+               return;
 
-       return ret;
+       if (rbd_dev_snap_index(rbd_dev, snap_id) == BAD_SNAP_INDEX)
+               clear_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);
 }
 
-static int rbd_dev_refresh(struct rbd_device *rbd_dev, u64 *hver)
+static int rbd_dev_refresh(struct rbd_device *rbd_dev)
 {
+       u64 mapping_size;
        int ret;
 
        rbd_assert(rbd_image_format_valid(rbd_dev->image_format));
+       mapping_size = rbd_dev->mapping.size;
        mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
        if (rbd_dev->image_format == 1)
-               ret = rbd_dev_v1_refresh(rbd_dev, hver);
+               ret = rbd_dev_v1_header_info(rbd_dev);
        else
-               ret = rbd_dev_v2_refresh(rbd_dev, hver);
+               ret = rbd_dev_v2_header_info(rbd_dev);
+
+       /* If it's a mapped snapshot, validate its EXISTS flag */
+
+       rbd_exists_validate(rbd_dev);
        mutex_unlock(&ctl_mutex);
-       revalidate_disk(rbd_dev->disk);
-       if (ret)
-               rbd_warn(rbd_dev, "got notification but failed to "
-                          " update snaps: %d\n", ret);
+       if (mapping_size != rbd_dev->mapping.size) {
+               sector_t size;
+
+               size = (sector_t)rbd_dev->mapping.size / SECTOR_SIZE;
+               dout("setting size to %llu sectors", (unsigned long long)size);
+               set_capacity(rbd_dev->disk, size);
+               revalidate_disk(rbd_dev->disk);
+       }
 
        return ret;
 }
@@ -3125,8 +3197,6 @@ static int rbd_init_disk(struct rbd_device *rbd_dev)
 
        rbd_dev->disk = disk;
 
-       set_capacity(rbd_dev->disk, rbd_dev->mapping.size / SECTOR_SIZE);
-
        return 0;
 out_disk:
        put_disk(disk);
@@ -3147,13 +3217,9 @@ static ssize_t rbd_size_show(struct device *dev,
                             struct device_attribute *attr, char *buf)
 {
        struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
-       sector_t size;
-
-       down_read(&rbd_dev->header_rwsem);
-       size = get_capacity(rbd_dev->disk);
-       up_read(&rbd_dev->header_rwsem);
 
-       return sprintf(buf, "%llu\n", (unsigned long long) size * SECTOR_SIZE);
+       return sprintf(buf, "%llu\n",
+               (unsigned long long)rbd_dev->mapping.size);
 }
 
 /*
@@ -3166,7 +3232,7 @@ static ssize_t rbd_features_show(struct device *dev,
        struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
 
        return sprintf(buf, "0x%016llx\n",
-                       (unsigned long long) rbd_dev->mapping.features);
+                       (unsigned long long)rbd_dev->mapping.features);
 }
 
 static ssize_t rbd_major_show(struct device *dev,
@@ -3174,7 +3240,11 @@ static ssize_t rbd_major_show(struct device *dev,
 {
        struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
 
-       return sprintf(buf, "%d\n", rbd_dev->major);
+       if (rbd_dev->major)
+               return sprintf(buf, "%d\n", rbd_dev->major);
+
+       return sprintf(buf, "(none)\n");
+
 }
 
 static ssize_t rbd_client_id_show(struct device *dev,
@@ -3200,7 +3270,7 @@ static ssize_t rbd_pool_id_show(struct device *dev,
        struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
 
        return sprintf(buf, "%llu\n",
-               (unsigned long long) rbd_dev->spec->pool_id);
+                       (unsigned long long) rbd_dev->spec->pool_id);
 }
 
 static ssize_t rbd_name_show(struct device *dev,
@@ -3286,7 +3356,9 @@ static ssize_t rbd_image_refresh(struct device *dev,
        struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
        int ret;
 
-       ret = rbd_dev_refresh(rbd_dev, NULL);
+       ret = rbd_dev_refresh(rbd_dev);
+       if (ret)
+               rbd_warn(rbd_dev, ": manual header refresh error (%d)\n", ret);
 
        return ret < 0 ? ret : size;
 }
@@ -3386,7 +3458,6 @@ static struct rbd_device *rbd_dev_create(struct rbd_client *rbdc,
        spin_lock_init(&rbd_dev->lock);
        rbd_dev->flags = 0;
        INIT_LIST_HEAD(&rbd_dev->node);
-       INIT_LIST_HEAD(&rbd_dev->snaps);
        init_rwsem(&rbd_dev->header_rwsem);
 
        rbd_dev->spec = spec;
@@ -3404,66 +3475,11 @@ static struct rbd_device *rbd_dev_create(struct rbd_client *rbdc,
 
 static void rbd_dev_destroy(struct rbd_device *rbd_dev)
 {
-       rbd_spec_put(rbd_dev->parent_spec);
-       kfree(rbd_dev->header_name);
        rbd_put_client(rbd_dev->rbd_client);
        rbd_spec_put(rbd_dev->spec);
        kfree(rbd_dev);
 }
 
-static void rbd_snap_destroy(struct rbd_snap *snap)
-{
-       kfree(snap->name);
-       kfree(snap);
-}
-
-static struct rbd_snap *rbd_snap_create(struct rbd_device *rbd_dev,
-                                               const char *snap_name,
-                                               u64 snap_id, u64 snap_size,
-                                               u64 snap_features)
-{
-       struct rbd_snap *snap;
-
-       snap = kzalloc(sizeof (*snap), GFP_KERNEL);
-       if (!snap)
-               return ERR_PTR(-ENOMEM);
-
-       snap->name = snap_name;
-       snap->id = snap_id;
-       snap->size = snap_size;
-       snap->features = snap_features;
-
-       return snap;
-}
-
-/*
- * Returns a dynamically-allocated snapshot name if successful, or a
- * pointer-coded error otherwise.
- */
-static char *rbd_dev_v1_snap_info(struct rbd_device *rbd_dev, u32 which,
-               u64 *snap_size, u64 *snap_features)
-{
-       char *snap_name;
-       int i;
-
-       rbd_assert(which < rbd_dev->header.snapc->num_snaps);
-
-       /* Skip over names until we find the one we are looking for */
-
-       snap_name = rbd_dev->header.snap_names;
-       for (i = 0; i < which; i++)
-               snap_name += strlen(snap_name) + 1;
-
-       snap_name = kstrdup(snap_name, GFP_KERNEL);
-       if (!snap_name)
-               return ERR_PTR(-ENOMEM);
-
-       *snap_size = rbd_dev->header.snap_sizes[which];
-       *snap_features = 0;     /* No features for v1 */
-
-       return snap_name;
-}
-
 /*
  * Get the size and object order for an image snapshot, or if
  * snap_id is CEPH_NOSNAP, gets this information for the base
@@ -3482,7 +3498,7 @@ static int _rbd_dev_v2_snap_size(struct rbd_device *rbd_dev, u64 snap_id,
        ret = rbd_obj_method_sync(rbd_dev, rbd_dev->header_name,
                                "rbd", "get_size",
                                &snapid, sizeof (snapid),
-                               &size_buf, sizeof (size_buf), NULL);
+                               &size_buf, sizeof (size_buf));
        dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
        if (ret < 0)
                return ret;
@@ -3519,7 +3535,7 @@ static int rbd_dev_v2_object_prefix(struct rbd_device *rbd_dev)
 
        ret = rbd_obj_method_sync(rbd_dev, rbd_dev->header_name,
                                "rbd", "get_object_prefix", NULL, 0,
-                               reply_buf, RBD_OBJ_PREFIX_LEN_MAX, NULL);
+                               reply_buf, RBD_OBJ_PREFIX_LEN_MAX);
        dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
        if (ret < 0)
                goto out;
@@ -3555,7 +3571,7 @@ static int _rbd_dev_v2_snap_features(struct rbd_device *rbd_dev, u64 snap_id,
        ret = rbd_obj_method_sync(rbd_dev, rbd_dev->header_name,
                                "rbd", "get_features",
                                &snapid, sizeof (snapid),
-                               &features_buf, sizeof (features_buf), NULL);
+                               &features_buf, sizeof (features_buf));
        dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
        if (ret < 0)
                return ret;
@@ -3612,7 +3628,7 @@ static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)
        ret = rbd_obj_method_sync(rbd_dev, rbd_dev->header_name,
                                "rbd", "get_parent",
                                &snapid, sizeof (snapid),
-                               reply_buf, size, NULL);
+                               reply_buf, size);
        dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
        if (ret < 0)
                goto out_err;
@@ -3627,8 +3643,11 @@ static int rbd_dev_v2_parent_info(struct rbd_device *rbd_dev)
        /* The ceph file layout needs to fit pool id in 32 bits */
 
        ret = -EIO;
-       if (WARN_ON(parent_spec->pool_id > (u64)U32_MAX))
+       if (parent_spec->pool_id > (u64)U32_MAX) {
+               rbd_warn(NULL, "parent pool id too large (%llu > %u)\n",
+                       (unsigned long long)parent_spec->pool_id, U32_MAX);
                goto out_err;
+       }
 
        image_id = ceph_extract_encoded_string(&p, end, NULL, GFP_KERNEL);
        if (IS_ERR(image_id)) {
@@ -3666,7 +3685,7 @@ static int rbd_dev_v2_striping_info(struct rbd_device *rbd_dev)
 
        ret = rbd_obj_method_sync(rbd_dev, rbd_dev->header_name,
                                "rbd", "get_stripe_unit_count", NULL, 0,
-                               (char *)&striping_info_buf, size, NULL);
+                               (char *)&striping_info_buf, size);
        dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
        if (ret < 0)
                return ret;
@@ -3695,8 +3714,8 @@ static int rbd_dev_v2_striping_info(struct rbd_device *rbd_dev)
                                "(got %llu want 1)", stripe_count);
                return -EINVAL;
        }
-       rbd_dev->stripe_unit = stripe_unit;
-       rbd_dev->stripe_count = stripe_count;
+       rbd_dev->header.stripe_unit = stripe_unit;
+       rbd_dev->header.stripe_count = stripe_count;
 
        return 0;
 }
@@ -3733,7 +3752,7 @@ static char *rbd_dev_image_name(struct rbd_device *rbd_dev)
        ret = rbd_obj_method_sync(rbd_dev, RBD_DIRECTORY,
                                "rbd", "dir_get_name",
                                image_id, image_id_size,
-                               reply_buf, size, NULL);
+                               reply_buf, size);
        if (ret < 0)
                goto out;
        p = reply_buf;
@@ -3751,89 +3770,134 @@ out:
        return image_name;
 }
 
-/*
- * When a parent image gets probed, we only have the pool, image,
- * and snapshot ids but not the names of any of them.  This call
- * is made later to fill in those names.  It has to be done after
- * rbd_dev_snaps_update() has completed because some of the
- * information (in particular, snapshot name) is not available
- * until then.
- *
- * When an image being mapped (not a parent) is probed, we have the
- * pool name and pool id, image name and image id, and the snapshot
- * name.  The only thing we're missing is the snapshot id.
- */
-static int rbd_dev_probe_update_spec(struct rbd_device *rbd_dev)
+static u64 rbd_v1_snap_id_by_name(struct rbd_device *rbd_dev, const char *name)
 {
-       struct ceph_osd_client *osdc;
-       const char *name;
-       void *reply_buf = NULL;
-       int ret;
+       struct ceph_snap_context *snapc = rbd_dev->header.snapc;
+       const char *snap_name;
+       u32 which = 0;
 
-       /*
+       /* Skip over names until we find the one we are looking for */
+
+       snap_name = rbd_dev->header.snap_names;
+       while (which < snapc->num_snaps) {
+               if (!strcmp(name, snap_name))
+                       return snapc->snaps[which];
+               snap_name += strlen(snap_name) + 1;
+               which++;
+       }
+       return CEPH_NOSNAP;
+}
+
+static u64 rbd_v2_snap_id_by_name(struct rbd_device *rbd_dev, const char *name)
+{
+       struct ceph_snap_context *snapc = rbd_dev->header.snapc;
+       u32 which;
+       bool found = false;
+       u64 snap_id;
+
+       for (which = 0; !found && which < snapc->num_snaps; which++) {
+               const char *snap_name;
+
+               snap_id = snapc->snaps[which];
+               snap_name = rbd_dev_v2_snap_name(rbd_dev, snap_id);
+               if (IS_ERR(snap_name))
+                       break;
+               found = !strcmp(name, snap_name);
+               kfree(snap_name);
+       }
+       return found ? snap_id : CEPH_NOSNAP;
+}
+
+/*
+ * Assumes name is never RBD_SNAP_HEAD_NAME; returns CEPH_NOSNAP if
+ * no snapshot by that name is found, or if an error occurs.
+ */
+static u64 rbd_snap_id_by_name(struct rbd_device *rbd_dev, const char *name)
+{
+       if (rbd_dev->image_format == 1)
+               return rbd_v1_snap_id_by_name(rbd_dev, name);
+
+       return rbd_v2_snap_id_by_name(rbd_dev, name);
+}
+
+/*
+ * When an rbd image has a parent image, it is identified by the
+ * pool, image, and snapshot ids (not names).  This function fills
+ * in the names for those ids.  (It's OK if we can't figure out the
+ * name for an image id, but the pool and snapshot ids should always
+ * exist and have names.)  All names in an rbd spec are dynamically
+ * allocated.
+ *
+ * When an image being mapped (not a parent) is probed, we have the
+ * pool name and pool id, image name and image id, and the snapshot
+ * name.  The only thing we're missing is the snapshot id.
+ */
+static int rbd_dev_spec_update(struct rbd_device *rbd_dev)
+{
+       struct ceph_osd_client *osdc = &rbd_dev->rbd_client->client->osdc;
+       struct rbd_spec *spec = rbd_dev->spec;
+       const char *pool_name;
+       const char *image_name;
+       const char *snap_name;
+       int ret;
+
+       /*
         * An image being mapped will have the pool name (etc.), but
         * we need to look up the snapshot id.
         */
-       if (rbd_dev->spec->pool_name) {
-               if (strcmp(rbd_dev->spec->snap_name, RBD_SNAP_HEAD_NAME)) {
-                       struct rbd_snap *snap;
+       if (spec->pool_name) {
+               if (strcmp(spec->snap_name, RBD_SNAP_HEAD_NAME)) {
+                       u64 snap_id;
 
-                       snap = snap_by_name(rbd_dev, rbd_dev->spec->snap_name);
-                       if (!snap)
+                       snap_id = rbd_snap_id_by_name(rbd_dev, spec->snap_name);
+                       if (snap_id == CEPH_NOSNAP)
                                return -ENOENT;
-                       rbd_dev->spec->snap_id = snap->id;
+                       spec->snap_id = snap_id;
                } else {
-                       rbd_dev->spec->snap_id = CEPH_NOSNAP;
+                       spec->snap_id = CEPH_NOSNAP;
                }
 
                return 0;
        }
 
-       /* Look up the pool name */
+       /* Get the pool name; we have to make our own copy of this */
 
-       osdc = &rbd_dev->rbd_client->client->osdc;
-       name = ceph_pg_pool_name_by_id(osdc->osdmap, rbd_dev->spec->pool_id);
-       if (!name) {
-               rbd_warn(rbd_dev, "there is no pool with id %llu",
-                       rbd_dev->spec->pool_id);        /* Really a BUG() */
+       pool_name = ceph_pg_pool_name_by_id(osdc->osdmap, spec->pool_id);
+       if (!pool_name) {
+               rbd_warn(rbd_dev, "no pool with id %llu", spec->pool_id);
                return -EIO;
        }
-
-       rbd_dev->spec->pool_name = kstrdup(name, GFP_KERNEL);
-       if (!rbd_dev->spec->pool_name)
+       pool_name = kstrdup(pool_name, GFP_KERNEL);
+       if (!pool_name)
                return -ENOMEM;
 
        /* Fetch the image name; tolerate failure here */
 
-       name = rbd_dev_image_name(rbd_dev);
-       if (name)
-               rbd_dev->spec->image_name = (char *)name;
-       else
+       image_name = rbd_dev_image_name(rbd_dev);
+       if (!image_name)
                rbd_warn(rbd_dev, "unable to get image name");
 
-       /* Look up the snapshot name. */
+       /* Look up the snapshot name, and make a copy */
 
-       name = rbd_snap_name(rbd_dev, rbd_dev->spec->snap_id);
-       if (!name) {
-               rbd_warn(rbd_dev, "no snapshot with id %llu",
-                       rbd_dev->spec->snap_id);        /* Really a BUG() */
-               ret = -EIO;
+       snap_name = rbd_snap_name(rbd_dev, spec->snap_id);
+       if (!snap_name) {
+               ret = -ENOMEM;
                goto out_err;
        }
-       rbd_dev->spec->snap_name = kstrdup(name, GFP_KERNEL);
-       if(!rbd_dev->spec->snap_name)
-               goto out_err;
+
+       spec->pool_name = pool_name;
+       spec->image_name = image_name;
+       spec->snap_name = snap_name;
 
        return 0;
 out_err:
-       kfree(reply_buf);
-       kfree(rbd_dev->spec->pool_name);
-       rbd_dev->spec->pool_name = NULL;
+       kfree(image_name);
+       kfree(pool_name);
 
        return ret;
 }
 
-static int rbd_dev_v2_snap_context(struct rbd_device *rbd_dev, u64 *ver)
+static int rbd_dev_v2_snap_context(struct rbd_device *rbd_dev)
 {
        size_t size;
        int ret;
@@ -3859,7 +3923,7 @@ static int rbd_dev_v2_snap_context(struct rbd_device *rbd_dev, u64 *ver)
 
        ret = rbd_obj_method_sync(rbd_dev, rbd_dev->header_name,
                                "rbd", "get_snapcontext", NULL, 0,
-                               reply_buf, size, ver);
+                               reply_buf, size);
        dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
        if (ret < 0)
                goto out;
@@ -3883,22 +3947,18 @@ static int rbd_dev_v2_snap_context(struct rbd_device *rbd_dev, u64 *ver)
        }
        if (!ceph_has_room(&p, end, snap_count * sizeof (__le64)))
                goto out;
+       ret = 0;
 
-       size = sizeof (struct ceph_snap_context) +
-                               snap_count * sizeof (snapc->snaps[0]);
-       snapc = kmalloc(size, GFP_KERNEL);
+       snapc = ceph_create_snap_context(snap_count, GFP_KERNEL);
        if (!snapc) {
                ret = -ENOMEM;
                goto out;
        }
-       ret = 0;
-
-       atomic_set(&snapc->nref, 1);
        snapc->seq = seq;
-       snapc->num_snaps = snap_count;
        for (i = 0; i < snap_count; i++)
                snapc->snaps[i] = ceph_decode_64(&p);
 
+       ceph_put_snap_context(rbd_dev->header.snapc);
        rbd_dev->header.snapc = snapc;
 
        dout("  snap context seq = %llu, snap_count = %u\n",
@@ -3909,11 +3969,12 @@ out:
        return ret;
 }
 
-static char *rbd_dev_v2_snap_name(struct rbd_device *rbd_dev, u32 which)
+static const char *rbd_dev_v2_snap_name(struct rbd_device *rbd_dev,
+                                       u64 snap_id)
 {
        size_t size;
        void *reply_buf;
-       __le64 snap_id;
+       __le64 snapid;
        int ret;
        void *p;
        void *end;
@@ -3924,12 +3985,11 @@ static char *rbd_dev_v2_snap_name(struct rbd_device *rbd_dev, u32 which)
        if (!reply_buf)
                return ERR_PTR(-ENOMEM);
 
-       rbd_assert(which < rbd_dev->header.snapc->num_snaps);
-       snap_id = cpu_to_le64(rbd_dev->header.snapc->snaps[which]);
+       snapid = cpu_to_le64(snap_id);
        ret = rbd_obj_method_sync(rbd_dev, rbd_dev->header_name,
                                "rbd", "get_snapshot_name",
-                               &snap_id, sizeof (snap_id),
-                               reply_buf, size, NULL);
+                               &snapid, sizeof (snapid),
+                               reply_buf, size);
        dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
        if (ret < 0) {
                snap_name = ERR_PTR(ret);
@@ -3943,213 +4003,43 @@ static char *rbd_dev_v2_snap_name(struct rbd_device *rbd_dev, u32 which)
                goto out;
 
        dout("  snap_id 0x%016llx snap_name = %s\n",
-               (unsigned long long)le64_to_cpu(snap_id), snap_name);
+               (unsigned long long)snap_id, snap_name);
 out:
        kfree(reply_buf);
 
        return snap_name;
 }
 
-static char *rbd_dev_v2_snap_info(struct rbd_device *rbd_dev, u32 which,
-               u64 *snap_size, u64 *snap_features)
+static int rbd_dev_v2_header_info(struct rbd_device *rbd_dev)
 {
-       u64 snap_id;
-       u64 size;
-       u64 features;
-       char *snap_name;
+       bool first_time = rbd_dev->header.object_prefix == NULL;
        int ret;
 
-       rbd_assert(which < rbd_dev->header.snapc->num_snaps);
-       snap_id = rbd_dev->header.snapc->snaps[which];
-       ret = _rbd_dev_v2_snap_size(rbd_dev, snap_id, NULL, &size);
-       if (ret)
-               goto out_err;
-
-       ret = _rbd_dev_v2_snap_features(rbd_dev, snap_id, &features);
-       if (ret)
-               goto out_err;
-
-       snap_name = rbd_dev_v2_snap_name(rbd_dev, which);
-       if (!IS_ERR(snap_name)) {
-               *snap_size = size;
-               *snap_features = features;
-       }
-
-       return snap_name;
-out_err:
-       return ERR_PTR(ret);
-}
-
-static char *rbd_dev_snap_info(struct rbd_device *rbd_dev, u32 which,
-               u64 *snap_size, u64 *snap_features)
-{
-       if (rbd_dev->image_format == 1)
-               return rbd_dev_v1_snap_info(rbd_dev, which,
-                                       snap_size, snap_features);
-       if (rbd_dev->image_format == 2)
-               return rbd_dev_v2_snap_info(rbd_dev, which,
-                                       snap_size, snap_features);
-       return ERR_PTR(-EINVAL);
-}
-
-static int rbd_dev_v2_refresh(struct rbd_device *rbd_dev, u64 *hver)
-{
-       int ret;
-       __u8 obj_order;
-
        down_write(&rbd_dev->header_rwsem);
 
-       /* Grab old order first, to see if it changes */
+       if (first_time) {
+               ret = rbd_dev_v2_header_onetime(rbd_dev);
+               if (ret)
+                       goto out;
+       }
 
-       obj_order = rbd_dev->header.obj_order,
        ret = rbd_dev_v2_image_size(rbd_dev);
        if (ret)
                goto out;
-       if (rbd_dev->header.obj_order != obj_order) {
-               ret = -EIO;
-               goto out;
-       }
-       rbd_update_mapping_size(rbd_dev);
+       if (rbd_dev->spec->snap_id == CEPH_NOSNAP)
+               if (rbd_dev->mapping.size != rbd_dev->header.image_size)
+                       rbd_dev->mapping.size = rbd_dev->header.image_size;
 
-       ret = rbd_dev_v2_snap_context(rbd_dev, hver);
+       ret = rbd_dev_v2_snap_context(rbd_dev);
        dout("rbd_dev_v2_snap_context returned %d\n", ret);
        if (ret)
                goto out;
-       ret = rbd_dev_snaps_update(rbd_dev);
-       dout("rbd_dev_snaps_update returned %d\n", ret);
-       if (ret)
-               goto out;
 out:
        up_write(&rbd_dev->header_rwsem);
 
        return ret;
 }
 
-/*
- * Scan the rbd device's current snapshot list and compare it to the
- * newly-received snapshot context.  Remove any existing snapshots
- * not present in the new snapshot context.  Add a new snapshot for
- * any snaphots in the snapshot context not in the current list.
- * And verify there are no changes to snapshots we already know
- * about.
- *
- * Assumes the snapshots in the snapshot context are sorted by
- * snapshot id, highest id first.  (Snapshots in the rbd_dev's list
- * are also maintained in that order.)
- *
- * Note that any error occurs while updating the snapshot list
- * aborts the update, and the entire list is cleared.  The snapshot
- * list becomes inconsistent at that point anyway, so it might as
- * well be empty.
- */
-static int rbd_dev_snaps_update(struct rbd_device *rbd_dev)
-{
-       struct ceph_snap_context *snapc = rbd_dev->header.snapc;
-       const u32 snap_count = snapc->num_snaps;
-       struct list_head *head = &rbd_dev->snaps;
-       struct list_head *links = head->next;
-       u32 index = 0;
-       int ret = 0;
-
-       dout("%s: snap count is %u\n", __func__, (unsigned int)snap_count);
-       while (index < snap_count || links != head) {
-               u64 snap_id;
-               struct rbd_snap *snap;
-               char *snap_name;
-               u64 snap_size = 0;
-               u64 snap_features = 0;
-
-               snap_id = index < snap_count ? snapc->snaps[index]
-                                            : CEPH_NOSNAP;
-               snap = links != head ? list_entry(links, struct rbd_snap, node)
-                                    : NULL;
-               rbd_assert(!snap || snap->id != CEPH_NOSNAP);
-
-               if (snap_id == CEPH_NOSNAP || (snap && snap->id > snap_id)) {
-                       struct list_head *next = links->next;
-
-                       /*
-                        * A previously-existing snapshot is not in
-                        * the new snap context.
-                        *
-                        * If the now-missing snapshot is the one
-                        * the image represents, clear its existence
-                        * flag so we can avoid sending any more
-                        * requests to it.
-                        */
-                       if (rbd_dev->spec->snap_id == snap->id)
-                               clear_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);
-                       dout("removing %ssnap id %llu\n",
-                               rbd_dev->spec->snap_id == snap->id ?
-                                                       "mapped " : "",
-                               (unsigned long long)snap->id);
-
-                       list_del(&snap->node);
-                       rbd_snap_destroy(snap);
-
-                       /* Done with this list entry; advance */
-
-                       links = next;
-                       continue;
-               }
-
-               snap_name = rbd_dev_snap_info(rbd_dev, index,
-                                       &snap_size, &snap_features);
-               if (IS_ERR(snap_name)) {
-                       ret = PTR_ERR(snap_name);
-                       dout("failed to get snap info, error %d\n", ret);
-                       goto out_err;
-               }
-
-               dout("entry %u: snap_id = %llu\n", (unsigned int)snap_count,
-                       (unsigned long long)snap_id);
-               if (!snap || (snap_id != CEPH_NOSNAP && snap->id < snap_id)) {
-                       struct rbd_snap *new_snap;
-
-                       /* We haven't seen this snapshot before */
-
-                       new_snap = rbd_snap_create(rbd_dev, snap_name,
-                                       snap_id, snap_size, snap_features);
-                       if (IS_ERR(new_snap)) {
-                               ret = PTR_ERR(new_snap);
-                               dout("  failed to add dev, error %d\n", ret);
-                               goto out_err;
-                       }
-
-                       /* New goes before existing, or at end of list */
-
-                       dout("  added dev%s\n", snap ? "" : " at end\n");
-                       if (snap)
-                               list_add_tail(&new_snap->node, &snap->node);
-                       else
-                               list_add_tail(&new_snap->node, head);
-               } else {
-                       /* Already have this one */
-
-                       dout("  already present\n");
-
-                       rbd_assert(snap->size == snap_size);
-                       rbd_assert(!strcmp(snap->name, snap_name));
-                       rbd_assert(snap->features == snap_features);
-
-                       /* Done with this list entry; advance */
-
-                       links = links->next;
-               }
-
-               /* Advance to the next entry in the snapshot context */
-
-               index++;
-       }
-       dout("%s: done\n", __func__);
-
-       return 0;
-out_err:
-       rbd_remove_all_snaps(rbd_dev);
-
-       return ret;
-}
-
 static int rbd_bus_add_dev(struct rbd_device *rbd_dev)
 {
        struct device *dev;
@@ -4161,7 +4051,7 @@ static int rbd_bus_add_dev(struct rbd_device *rbd_dev)
        dev->bus = &rbd_bus_type;
        dev->type = &rbd_device_type;
        dev->parent = &rbd_root_dev;
-       dev->release = rbd_dev_release;
+       dev->release = rbd_dev_device_release;
        dev_set_name(dev, "%d", rbd_dev->dev_id);
        ret = device_register(dev);
 
@@ -4375,6 +4265,7 @@ static int rbd_add_parse_args(const char *buf,
        size_t len;
        char *options;
        const char *mon_addrs;
+       char *snap_name;
        size_t mon_addrs_size;
        struct rbd_spec *spec = NULL;
        struct rbd_options *rbd_opts = NULL;
@@ -4433,10 +4324,11 @@ static int rbd_add_parse_args(const char *buf,
                ret = -ENAMETOOLONG;
                goto out_err;
        }
-       spec->snap_name = kmemdup(buf, len + 1, GFP_KERNEL);
-       if (!spec->snap_name)
+       snap_name = kmemdup(buf, len + 1, GFP_KERNEL);
+       if (!snap_name)
                goto out_mem;
-       *(spec->snap_name + len) = '\0';
+       *(snap_name + len) = '\0';
+       spec->snap_name = snap_name;
 
        /* Initialize all rbd options to the defaults */
 
@@ -4528,7 +4420,7 @@ static int rbd_dev_image_id(struct rbd_device *rbd_dev)
 
        ret = rbd_obj_method_sync(rbd_dev, object_name,
                                "rbd", "get_id", NULL, 0,
-                               response, RBD_IMAGE_ID_LEN_MAX, NULL);
+                               response, RBD_IMAGE_ID_LEN_MAX);
        dout("%s: rbd_obj_method_sync returned %d\n", __func__, ret);
        if (ret == -ENOENT) {
                image_id = kstrdup("", GFP_KERNEL);
@@ -4558,77 +4450,39 @@ out:
        return ret;
 }
 
-static int rbd_dev_v1_probe(struct rbd_device *rbd_dev)
-{
-       int ret;
-       size_t size;
-
-       /* Record the header object name for this rbd image. */
+/* Undo whatever state changes are made by v1 or v2 image probe */
 
-       size = strlen(rbd_dev->spec->image_name) + sizeof (RBD_SUFFIX);
-       rbd_dev->header_name = kmalloc(size, GFP_KERNEL);
-       if (!rbd_dev->header_name) {
-               ret = -ENOMEM;
-               goto out_err;
-       }
-       sprintf(rbd_dev->header_name, "%s%s",
-               rbd_dev->spec->image_name, RBD_SUFFIX);
-
-       /* Populate rbd image metadata */
-
-       ret = rbd_read_header(rbd_dev, &rbd_dev->header);
-       if (ret < 0)
-               goto out_err;
-
-       /* Version 1 images have no parent (no layering) */
+static void rbd_dev_unprobe(struct rbd_device *rbd_dev)
+{
+       struct rbd_image_header *header;
 
+       rbd_dev_remove_parent(rbd_dev);
+       rbd_spec_put(rbd_dev->parent_spec);
        rbd_dev->parent_spec = NULL;
        rbd_dev->parent_overlap = 0;
 
-       dout("discovered version 1 image, header name is %s\n",
-               rbd_dev->header_name);
-
-       return 0;
-
-out_err:
-       kfree(rbd_dev->header_name);
-       rbd_dev->header_name = NULL;
-       kfree(rbd_dev->spec->image_id);
-       rbd_dev->spec->image_id = NULL;
+       /* Free dynamic fields from the header, then zero it out */
 
-       return ret;
+       header = &rbd_dev->header;
+       ceph_put_snap_context(header->snapc);
+       kfree(header->snap_sizes);
+       kfree(header->snap_names);
+       kfree(header->object_prefix);
+       memset(header, 0, sizeof (*header));
 }
 
-static int rbd_dev_v2_probe(struct rbd_device *rbd_dev)
+static int rbd_dev_v2_header_onetime(struct rbd_device *rbd_dev)
 {
-       size_t size;
        int ret;
-       u64 ver = 0;
-
-       /*
-        * Image id was filled in by the caller.  Record the header
-        * object name for this rbd image.
-        */
-       size = sizeof (RBD_HEADER_PREFIX) + strlen(rbd_dev->spec->image_id);
-       rbd_dev->header_name = kmalloc(size, GFP_KERNEL);
-       if (!rbd_dev->header_name)
-               return -ENOMEM;
-       sprintf(rbd_dev->header_name, "%s%s",
-                       RBD_HEADER_PREFIX, rbd_dev->spec->image_id);
-
-       /* Get the size and object order for the image */
-       ret = rbd_dev_v2_image_size(rbd_dev);
-       if (ret)
-               goto out_err;
-
-       /* Get the object prefix (a.k.a. block_name) for the image */
 
        ret = rbd_dev_v2_object_prefix(rbd_dev);
        if (ret)
                goto out_err;
 
-       /* Get the and check features for the image */
-
+       /*
+        * Get the and check features for the image.  Currently the
+        * features are assumed to never change.
+        */
        ret = rbd_dev_v2_features(rbd_dev);
        if (ret)
                goto out_err;
@@ -4639,8 +4493,16 @@ static int rbd_dev_v2_probe(struct rbd_device *rbd_dev)
                ret = rbd_dev_v2_parent_info(rbd_dev);
                if (ret)
                        goto out_err;
-               rbd_warn(rbd_dev, "WARNING: kernel support for "
-                                       "layered rbd images is EXPERIMENTAL!");
+               /*
+                * Print a warning if this image has a parent.
+                * Don't print it if the image now being probed
+                * is itself a parent.  We can tell at this point
+                * because we won't know its pool name yet (just its
+                * pool id).
+                */
+               if (rbd_dev->parent_spec && rbd_dev->spec->pool_name)
+                       rbd_warn(rbd_dev, "WARNING: kernel layering "
+                                       "is EXPERIMENTAL!");
        }
 
        /* If the image supports fancy striping, get its parameters */
@@ -4650,21 +4512,7 @@ static int rbd_dev_v2_probe(struct rbd_device *rbd_dev)
                if (ret < 0)
                        goto out_err;
        }
-
-       /* crypto and compression type aren't (yet) supported for v2 images */
-
-       rbd_dev->header.crypt_type = 0;
-       rbd_dev->header.comp_type = 0;
-
-       /* Get the snapshot context, plus the header version */
-
-       ret = rbd_dev_v2_snap_context(rbd_dev, &ver);
-       if (ret)
-               goto out_err;
-       rbd_dev->header.obj_version = ver;
-
-       dout("discovered version 2 image, header name is %s\n",
-               rbd_dev->header_name);
+       /* No support for crypto and compression type format 2 images */
 
        return 0;
 out_err:
@@ -4679,25 +4527,50 @@ out_err:
        return ret;
 }
 
-static int rbd_dev_probe_finish(struct rbd_device *rbd_dev)
+static int rbd_dev_probe_parent(struct rbd_device *rbd_dev)
 {
        struct rbd_device *parent = NULL;
-       struct rbd_spec *parent_spec = NULL;
-       struct rbd_client *rbdc = NULL;
+       struct rbd_spec *parent_spec;
+       struct rbd_client *rbdc;
        int ret;
 
-       /* no need to lock here, as rbd_dev is not registered yet */
-       ret = rbd_dev_snaps_update(rbd_dev);
-       if (ret)
-               return ret;
+       if (!rbd_dev->parent_spec)
+               return 0;
+       /*
+        * We need to pass a reference to the client and the parent
+        * spec when creating the parent rbd_dev.  Images related by
+        * parent/child relationships always share both.
+        */
+       parent_spec = rbd_spec_get(rbd_dev->parent_spec);
+       rbdc = __rbd_get_client(rbd_dev->rbd_client);
 
-       ret = rbd_dev_probe_update_spec(rbd_dev);
-       if (ret)
-               goto err_out_snaps;
+       ret = -ENOMEM;
+       parent = rbd_dev_create(rbdc, parent_spec);
+       if (!parent)
+               goto out_err;
 
-       ret = rbd_dev_set_mapping(rbd_dev);
-       if (ret)
-               goto err_out_snaps;
+       ret = rbd_dev_image_probe(parent, true);
+       if (ret < 0)
+               goto out_err;
+       rbd_dev->parent = parent;
+
+       return 0;
+out_err:
+       if (parent) {
+               rbd_spec_put(rbd_dev->parent_spec);
+               kfree(rbd_dev->header_name);
+               rbd_dev_destroy(parent);
+       } else {
+               rbd_put_client(rbdc);
+               rbd_spec_put(parent_spec);
+       }
+
+       return ret;
+}
+
+static int rbd_dev_device_setup(struct rbd_device *rbd_dev)
+{
+       int ret;
 
        /* generate unique id: find highest unique id, add one */
        rbd_dev_id_get(rbd_dev);
@@ -4720,45 +4593,18 @@ static int rbd_dev_probe_finish(struct rbd_device *rbd_dev)
        if (ret)
                goto err_out_blkdev;
 
-       ret = rbd_bus_add_dev(rbd_dev);
+       ret = rbd_dev_mapping_set(rbd_dev);
        if (ret)
                goto err_out_disk;
+       set_capacity(rbd_dev->disk, rbd_dev->mapping.size / SECTOR_SIZE);
 
-       /*
-        * At this point cleanup in the event of an error is the job
-        * of the sysfs code (initiated by rbd_bus_del_dev()).
-        */
-       /* Probe the parent if there is one */
-
-       if (rbd_dev->parent_spec) {
-               /*
-                * We need to pass a reference to the client and the
-                * parent spec when creating the parent rbd_dev.
-                * Images related by parent/child relationships
-                * always share both.
-                */
-               parent_spec = rbd_spec_get(rbd_dev->parent_spec);
-               rbdc = __rbd_get_client(rbd_dev->rbd_client);
-
-               parent = rbd_dev_create(rbdc, parent_spec);
-               if (!parent) {
-                       ret = -ENOMEM;
-                       goto err_out_spec;
-               }
-               rbdc = NULL;            /* parent now owns reference */
-               parent_spec = NULL;     /* parent now owns reference */
-               ret = rbd_dev_probe(parent);
-               if (ret < 0)
-                       goto err_out_parent;
-               rbd_dev->parent = parent;
-       }
-
-       ret = rbd_dev_header_watch_sync(rbd_dev, 1);
+       ret = rbd_bus_add_dev(rbd_dev);
        if (ret)
-               goto err_out_bus;
+               goto err_out_mapping;
 
        /* Everything's ready.  Announce the disk to the world. */
 
+       set_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);
        add_disk(rbd_dev->disk);
 
        pr_info("%s: added with size 0x%llx\n", rbd_dev->disk->disk_name,
@@ -4766,37 +4612,72 @@ static int rbd_dev_probe_finish(struct rbd_device *rbd_dev)
 
        return ret;
 
-err_out_parent:
-       rbd_dev_destroy(parent);
-err_out_spec:
-       rbd_spec_put(parent_spec);
-       rbd_put_client(rbdc);
-err_out_bus:
-       /* this will also clean up rest of rbd_dev stuff */
-
-       rbd_bus_del_dev(rbd_dev);
-
-       return ret;
+err_out_mapping:
+       rbd_dev_mapping_clear(rbd_dev);
 err_out_disk:
        rbd_free_disk(rbd_dev);
 err_out_blkdev:
        unregister_blkdev(rbd_dev->major, rbd_dev->name);
 err_out_id:
        rbd_dev_id_put(rbd_dev);
-err_out_snaps:
-       rbd_remove_all_snaps(rbd_dev);
+       rbd_dev_mapping_clear(rbd_dev);
 
        return ret;
 }
 
+static int rbd_dev_header_name(struct rbd_device *rbd_dev)
+{
+       struct rbd_spec *spec = rbd_dev->spec;
+       size_t size;
+
+       /* Record the header object name for this rbd image. */
+
+       rbd_assert(rbd_image_format_valid(rbd_dev->image_format));
+
+       if (rbd_dev->image_format == 1)
+               size = strlen(spec->image_name) + sizeof (RBD_SUFFIX);
+       else
+               size = sizeof (RBD_HEADER_PREFIX) + strlen(spec->image_id);
+
+       rbd_dev->header_name = kmalloc(size, GFP_KERNEL);
+       if (!rbd_dev->header_name)
+               return -ENOMEM;
+
+       if (rbd_dev->image_format == 1)
+               sprintf(rbd_dev->header_name, "%s%s",
+                       spec->image_name, RBD_SUFFIX);
+       else
+               sprintf(rbd_dev->header_name, "%s%s",
+                       RBD_HEADER_PREFIX, spec->image_id);
+       return 0;
+}
+
+static void rbd_dev_image_release(struct rbd_device *rbd_dev)
+{
+       int ret;
+
+       rbd_dev_unprobe(rbd_dev);
+       ret = rbd_dev_header_watch_sync(rbd_dev, 0);
+       if (ret)
+               rbd_warn(rbd_dev, "failed to cancel watch event (%d)\n", ret);
+       kfree(rbd_dev->header_name);
+       rbd_dev->header_name = NULL;
+       rbd_dev->image_format = 0;
+       kfree(rbd_dev->spec->image_id);
+       rbd_dev->spec->image_id = NULL;
+
+       rbd_dev_destroy(rbd_dev);
+}
+
 /*
  * Probe for the existence of the header object for the given rbd
  * device.  For format 2 images this includes determining the image
  * id.
  */
-static int rbd_dev_probe(struct rbd_device *rbd_dev)
+static int rbd_dev_image_probe(struct rbd_device *rbd_dev, bool read_only)
 {
        int ret;
+       int tmp;
 
        /*
         * Get the id from the image id object.  If it's not a
@@ -4809,19 +4690,50 @@ static int rbd_dev_probe(struct rbd_device *rbd_dev)
        rbd_assert(rbd_dev->spec->image_id);
        rbd_assert(rbd_image_format_valid(rbd_dev->image_format));
 
+       ret = rbd_dev_header_name(rbd_dev);
+       if (ret)
+               goto err_out_format;
+
+       ret = rbd_dev_header_watch_sync(rbd_dev, 1);
+       if (ret)
+               goto out_header_name;
+
        if (rbd_dev->image_format == 1)
-               ret = rbd_dev_v1_probe(rbd_dev);
+               ret = rbd_dev_v1_header_info(rbd_dev);
        else
-               ret = rbd_dev_v2_probe(rbd_dev);
+               ret = rbd_dev_v2_header_info(rbd_dev);
        if (ret)
-               goto out_err;
+               goto err_out_watch;
 
-       ret = rbd_dev_probe_finish(rbd_dev);
+       ret = rbd_dev_spec_update(rbd_dev);
        if (ret)
-               rbd_header_free(&rbd_dev->header);
+               goto err_out_probe;
 
-       return ret;
-out_err:
+       /* If we are mapping a snapshot it must be marked read-only */
+
+       if (rbd_dev->spec->snap_id != CEPH_NOSNAP)
+               read_only = true;
+       rbd_dev->mapping.read_only = read_only;
+
+       ret = rbd_dev_probe_parent(rbd_dev);
+       if (ret)
+               goto err_out_probe;
+
+       dout("discovered format %u image, header name is %s\n",
+               rbd_dev->image_format, rbd_dev->header_name);
+
+       return 0;
+err_out_probe:
+       rbd_dev_unprobe(rbd_dev);
+err_out_watch:
+       tmp = rbd_dev_header_watch_sync(rbd_dev, 0);
+       if (tmp)
+               rbd_warn(rbd_dev, "unable to tear down watch request\n");
+out_header_name:
+       kfree(rbd_dev->header_name);
+       rbd_dev->header_name = NULL;
+err_out_format:
+       rbd_dev->image_format = 0;
        kfree(rbd_dev->spec->image_id);
        rbd_dev->spec->image_id = NULL;
 
@@ -4840,6 +4752,7 @@ static ssize_t rbd_add(struct bus_type *bus,
        struct rbd_spec *spec = NULL;
        struct rbd_client *rbdc;
        struct ceph_osd_client *osdc;
+       bool read_only;
        int rc = -ENOMEM;
 
        if (!try_module_get(THIS_MODULE))
@@ -4849,6 +4762,9 @@ static ssize_t rbd_add(struct bus_type *bus,
        rc = rbd_add_parse_args(buf, &ceph_opts, &rbd_opts, &spec);
        if (rc < 0)
                goto err_out_module;
+       read_only = rbd_opts->read_only;
+       kfree(rbd_opts);
+       rbd_opts = NULL;        /* done with this */
 
        rbdc = rbd_get_client(ceph_opts);
        if (IS_ERR(rbdc)) {
@@ -4862,11 +4778,13 @@ static ssize_t rbd_add(struct bus_type *bus,
        rc = ceph_pg_poolid_by_name(osdc->osdmap, spec->pool_name);
        if (rc < 0)
                goto err_out_client;
-       spec->pool_id = (u64) rc;
+       spec->pool_id = (u64)rc;
 
        /* The ceph file layout needs to fit pool id in 32 bits */
 
-       if (WARN_ON(spec->pool_id > (u64) U32_MAX)) {
+       if (spec->pool_id > (u64)U32_MAX) {
+               rbd_warn(NULL, "pool id too large (%llu > %u)\n",
+                               (unsigned long long)spec->pool_id, U32_MAX);
                rc = -EIO;
                goto err_out_client;
        }
@@ -4877,15 +4795,15 @@ static ssize_t rbd_add(struct bus_type *bus,
        rbdc = NULL;            /* rbd_dev now owns this */
        spec = NULL;            /* rbd_dev now owns this */
 
-       rbd_dev->mapping.read_only = rbd_opts->read_only;
-       kfree(rbd_opts);
-       rbd_opts = NULL;        /* done with this */
-
-       rc = rbd_dev_probe(rbd_dev);
+       rc = rbd_dev_image_probe(rbd_dev, read_only);
        if (rc < 0)
                goto err_out_rbd_dev;
 
-       return count;
+       rc = rbd_dev_device_setup(rbd_dev);
+       if (!rc)
+               return count;
+
+       rbd_dev_image_release(rbd_dev);
 err_out_rbd_dev:
        rbd_dev_destroy(rbd_dev);
 err_out_client:
@@ -4900,7 +4818,7 @@ err_out_module:
 
        dout("Error adding device %s\n", buf);
 
-       return (ssize_t) rc;
+       return (ssize_t)rc;
 }
 
 static struct rbd_device *__rbd_get_dev(unsigned long dev_id)
@@ -4920,33 +4838,43 @@ static struct rbd_device *__rbd_get_dev(unsigned long dev_id)
        return NULL;
 }
 
-static void rbd_dev_release(struct device *dev)
+static void rbd_dev_device_release(struct device *dev)
 {
        struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
 
-       if (rbd_dev->watch_event)
-               rbd_dev_header_watch_sync(rbd_dev, 0);
-
-       /* clean up and free blkdev */
        rbd_free_disk(rbd_dev);
+       clear_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);
+       rbd_dev_mapping_clear(rbd_dev);
        unregister_blkdev(rbd_dev->major, rbd_dev->name);
-
-       /* release allocated disk header fields */
-       rbd_header_free(&rbd_dev->header);
-
-       /* done with the id, and with the rbd_dev */
+       rbd_dev->major = 0;
        rbd_dev_id_put(rbd_dev);
-       rbd_assert(rbd_dev->rbd_client != NULL);
-       rbd_dev_destroy(rbd_dev);
-
-       /* release module ref */
-       module_put(THIS_MODULE);
+       rbd_dev_mapping_clear(rbd_dev);
 }
 
-static void __rbd_remove(struct rbd_device *rbd_dev)
+static void rbd_dev_remove_parent(struct rbd_device *rbd_dev)
 {
-       rbd_remove_all_snaps(rbd_dev);
-       rbd_bus_del_dev(rbd_dev);
+       while (rbd_dev->parent) {
+               struct rbd_device *first = rbd_dev;
+               struct rbd_device *second = first->parent;
+               struct rbd_device *third;
+
+               /*
+                * Follow to the parent with no grandparent and
+                * remove it.
+                */
+               while (second && (third = second->parent)) {
+                       first = second;
+                       second = third;
+               }
+               rbd_assert(second);
+               rbd_dev_image_release(second);
+               first->parent = NULL;
+               first->parent_overlap = 0;
+
+               rbd_assert(first->parent_spec);
+               rbd_spec_put(first->parent_spec);
+               first->parent_spec = NULL;
+       }
 }
 
 static ssize_t rbd_remove(struct bus_type *bus,
@@ -4954,13 +4882,13 @@ static ssize_t rbd_remove(struct bus_type *bus,
                          size_t count)
 {
        struct rbd_device *rbd_dev = NULL;
-       int target_id, rc;
+       int target_id;
        unsigned long ul;
-       int ret = count;
+       int ret;
 
-       rc = strict_strtoul(buf, 10, &ul);
-       if (rc)
-               return rc;
+       ret = strict_strtoul(buf, 10, &ul);
+       if (ret)
+               return ret;
 
        /* convert to int; abort if we lost anything in the conversion */
        target_id = (int) ul;
@@ -4983,28 +4911,10 @@ static ssize_t rbd_remove(struct bus_type *bus,
        spin_unlock_irq(&rbd_dev->lock);
        if (ret < 0)
                goto done;
-
-       while (rbd_dev->parent_spec) {
-               struct rbd_device *first = rbd_dev;
-               struct rbd_device *second = first->parent;
-               struct rbd_device *third;
-
-               /*
-                * Follow to the parent with no grandparent and
-                * remove it.
-                */
-               while (second && (third = second->parent)) {
-                       first = second;
-                       second = third;
-               }
-               __rbd_remove(second);
-               rbd_spec_put(first->parent_spec);
-               first->parent_spec = NULL;
-               first->parent_overlap = 0;
-               first->parent = NULL;
-       }
-       __rbd_remove(rbd_dev);
-
+       ret = count;
+       rbd_bus_del_dev(rbd_dev);
+       rbd_dev_image_release(rbd_dev);
+       module_put(THIS_MODULE);
 done:
        mutex_unlock(&ctl_mutex);
 
@@ -5036,6 +4946,56 @@ static void rbd_sysfs_cleanup(void)
        device_unregister(&rbd_root_dev);
 }
 
+static int rbd_slab_init(void)
+{
+       rbd_assert(!rbd_img_request_cache);
+       rbd_img_request_cache = kmem_cache_create("rbd_img_request",
+                                       sizeof (struct rbd_img_request),
+                                       __alignof__(struct rbd_img_request),
+                                       0, NULL);
+       if (!rbd_img_request_cache)
+               return -ENOMEM;
+
+       rbd_assert(!rbd_obj_request_cache);
+       rbd_obj_request_cache = kmem_cache_create("rbd_obj_request",
+                                       sizeof (struct rbd_obj_request),
+                                       __alignof__(struct rbd_obj_request),
+                                       0, NULL);
+       if (!rbd_obj_request_cache)
+               goto out_err;
+
+       rbd_assert(!rbd_segment_name_cache);
+       rbd_segment_name_cache = kmem_cache_create("rbd_segment_name",
+                                       MAX_OBJ_NAME_SIZE + 1, 1, 0, NULL);
+       if (rbd_segment_name_cache)
+               return 0;
+out_err:
+       if (rbd_obj_request_cache) {
+               kmem_cache_destroy(rbd_obj_request_cache);
+               rbd_obj_request_cache = NULL;
+       }
+
+       kmem_cache_destroy(rbd_img_request_cache);
+       rbd_img_request_cache = NULL;
+
+       return -ENOMEM;
+}
+
+static void rbd_slab_exit(void)
+{
+       rbd_assert(rbd_segment_name_cache);
+       kmem_cache_destroy(rbd_segment_name_cache);
+       rbd_segment_name_cache = NULL;
+
+       rbd_assert(rbd_obj_request_cache);
+       kmem_cache_destroy(rbd_obj_request_cache);
+       rbd_obj_request_cache = NULL;
+
+       rbd_assert(rbd_img_request_cache);
+       kmem_cache_destroy(rbd_img_request_cache);
+       rbd_img_request_cache = NULL;
+}
+
 static int __init rbd_init(void)
 {
        int rc;
@@ -5045,16 +5005,22 @@ static int __init rbd_init(void)
 
                return -EINVAL;
        }
-       rc = rbd_sysfs_init();
+       rc = rbd_slab_init();
        if (rc)
                return rc;
-       pr_info("loaded " RBD_DRV_NAME_LONG "\n");
-       return 0;
+       rc = rbd_sysfs_init();
+       if (rc)
+               rbd_slab_exit();
+       else
+               pr_info("loaded " RBD_DRV_NAME_LONG "\n");
+
+       return rc;
 }
 
 static void __exit rbd_exit(void)
 {
        rbd_sysfs_cleanup();
+       rbd_slab_exit();
 }
 
 module_init(rbd_init);