extent_io.o volumes.o async-thread.o ioctl.o locking.o orphan.o \
export.o tree-log.o free-space-cache.o zlib.o lzo.o \
compression.o delayed-ref.o relocation.o delayed-inode.o scrub.o \
- reada.o backref.o
+ reada.o backref.o ulist.o
btrfs-$(CONFIG_BTRFS_FS_POSIX_ACL) += acl.o
#include "ctree.h"
#include "disk-io.h"
#include "backref.h"
+#include "ulist.h"
+#include "transaction.h"
+#include "delayed-ref.h"
-struct __data_ref {
+/*
+ * this structure records all encountered refs on the way up to the root
+ */
+struct __prelim_ref {
struct list_head list;
- u64 inum;
- u64 root;
- u64 extent_data_item_offset;
+ u64 root_id;
+ struct btrfs_key key;
+ int level;
+ int count;
+ u64 parent;
+ u64 wanted_disk_byte;
};
-struct __shared_ref {
- struct list_head list;
+static int __add_prelim_ref(struct list_head *head, u64 root_id,
+ struct btrfs_key *key, int level, u64 parent,
+ u64 wanted_disk_byte, int count)
+{
+ struct __prelim_ref *ref;
+
+ /* in case we're adding delayed refs, we're holding the refs spinlock */
+ ref = kmalloc(sizeof(*ref), GFP_ATOMIC);
+ if (!ref)
+ return -ENOMEM;
+
+ ref->root_id = root_id;
+ if (key)
+ ref->key = *key;
+ else
+ memset(&ref->key, 0, sizeof(ref->key));
+
+ ref->level = level;
+ ref->count = count;
+ ref->parent = parent;
+ ref->wanted_disk_byte = wanted_disk_byte;
+ list_add_tail(&ref->list, head);
+
+ return 0;
+}
+
+static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
+ struct ulist *parents,
+ struct extent_buffer *eb, int level,
+ u64 wanted_objectid, u64 wanted_disk_byte)
+{
+ int ret;
+ int slot;
+ struct btrfs_file_extent_item *fi;
+ struct btrfs_key key;
u64 disk_byte;
-};
+
+add_parent:
+ ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
+ if (ret < 0)
+ return ret;
+
+ if (level != 0)
+ return 0;
+
+ /*
+ * if the current leaf is full with EXTENT_DATA items, we must
+ * check the next one if that holds a reference as well.
+ * ref->count cannot be used to skip this check.
+ * repeat this until we don't find any additional EXTENT_DATA items.
+ */
+ while (1) {
+ ret = btrfs_next_leaf(root, path);
+ if (ret < 0)
+ return ret;
+ if (ret)
+ return 0;
+
+ eb = path->nodes[0];
+ for (slot = 0; slot < btrfs_header_nritems(eb); ++slot) {
+ btrfs_item_key_to_cpu(eb, &key, slot);
+ if (key.objectid != wanted_objectid ||
+ key.type != BTRFS_EXTENT_DATA_KEY)
+ return 0;
+ fi = btrfs_item_ptr(eb, slot,
+ struct btrfs_file_extent_item);
+ disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
+ if (disk_byte == wanted_disk_byte)
+ goto add_parent;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * resolve an indirect backref in the form (root_id, key, level)
+ * to a logical address
+ */
+static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
+ struct __prelim_ref *ref,
+ struct ulist *parents)
+{
+ struct btrfs_path *path;
+ struct btrfs_root *root;
+ struct btrfs_key root_key;
+ struct btrfs_key key = {0};
+ struct extent_buffer *eb;
+ int ret = 0;
+ int root_level;
+ int level = ref->level;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ root_key.objectid = ref->root_id;
+ root_key.type = BTRFS_ROOT_ITEM_KEY;
+ root_key.offset = (u64)-1;
+ root = btrfs_read_fs_root_no_name(fs_info, &root_key);
+ if (IS_ERR(root)) {
+ ret = PTR_ERR(root);
+ goto out;
+ }
+
+ rcu_read_lock();
+ root_level = btrfs_header_level(root->node);
+ rcu_read_unlock();
+
+ if (root_level + 1 == level)
+ goto out;
+
+ path->lowest_level = level;
+ ret = btrfs_search_slot(NULL, root, &ref->key, path, 0, 0);
+ pr_debug("search slot in root %llu (level %d, ref count %d) returned "
+ "%d for key (%llu %u %llu)\n",
+ (unsigned long long)ref->root_id, level, ref->count, ret,
+ (unsigned long long)ref->key.objectid, ref->key.type,
+ (unsigned long long)ref->key.offset);
+ if (ret < 0)
+ goto out;
+
+ eb = path->nodes[level];
+ if (!eb) {
+ WARN_ON(1);
+ ret = 1;
+ goto out;
+ }
+
+ if (level == 0) {
+ if (ret == 1 && path->slots[0] >= btrfs_header_nritems(eb)) {
+ ret = btrfs_next_leaf(root, path);
+ if (ret)
+ goto out;
+ eb = path->nodes[0];
+ }
+
+ btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
+ }
+
+ /* the last two parameters will only be used for level == 0 */
+ ret = add_all_parents(root, path, parents, eb, level, key.objectid,
+ ref->wanted_disk_byte);
+out:
+ btrfs_free_path(path);
+ return ret;
+}
+
+/*
+ * resolve all indirect backrefs from the list
+ */
+static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
+ struct list_head *head)
+{
+ int err;
+ int ret = 0;
+ struct __prelim_ref *ref;
+ struct __prelim_ref *ref_safe;
+ struct __prelim_ref *new_ref;
+ struct ulist *parents;
+ struct ulist_node *node;
+
+ parents = ulist_alloc(GFP_NOFS);
+ if (!parents)
+ return -ENOMEM;
+
+ /*
+ * _safe allows us to insert directly after the current item without
+ * iterating over the newly inserted items.
+ * we're also allowed to re-assign ref during iteration.
+ */
+ list_for_each_entry_safe(ref, ref_safe, head, list) {
+ if (ref->parent) /* already direct */
+ continue;
+ if (ref->count == 0)
+ continue;
+ err = __resolve_indirect_ref(fs_info, ref, parents);
+ if (err) {
+ if (ret == 0)
+ ret = err;
+ continue;
+ }
+
+ /* we put the first parent into the ref at hand */
+ node = ulist_next(parents, NULL);
+ ref->parent = node ? node->val : 0;
+
+ /* additional parents require new refs being added here */
+ while ((node = ulist_next(parents, node))) {
+ new_ref = kmalloc(sizeof(*new_ref), GFP_NOFS);
+ if (!new_ref) {
+ ret = -ENOMEM;
+ break;
+ }
+ memcpy(new_ref, ref, sizeof(*ref));
+ new_ref->parent = node->val;
+ list_add(&new_ref->list, &ref->list);
+ }
+ ulist_reinit(parents);
+ }
+
+ ulist_free(parents);
+ return ret;
+}
+
+/*
+ * merge two lists of backrefs and adjust counts accordingly
+ *
+ * mode = 1: merge identical keys, if key is set
+ * mode = 2: merge identical parents
+ */
+static int __merge_refs(struct list_head *head, int mode)
+{
+ struct list_head *pos1;
+
+ list_for_each(pos1, head) {
+ struct list_head *n2;
+ struct list_head *pos2;
+ struct __prelim_ref *ref1;
+
+ ref1 = list_entry(pos1, struct __prelim_ref, list);
+
+ if (mode == 1 && ref1->key.type == 0)
+ continue;
+ for (pos2 = pos1->next, n2 = pos2->next; pos2 != head;
+ pos2 = n2, n2 = pos2->next) {
+ struct __prelim_ref *ref2;
+
+ ref2 = list_entry(pos2, struct __prelim_ref, list);
+
+ if (mode == 1) {
+ if (memcmp(&ref1->key, &ref2->key,
+ sizeof(ref1->key)) ||
+ ref1->level != ref2->level ||
+ ref1->root_id != ref2->root_id)
+ continue;
+ ref1->count += ref2->count;
+ } else {
+ if (ref1->parent != ref2->parent)
+ continue;
+ ref1->count += ref2->count;
+ }
+ list_del(&ref2->list);
+ kfree(ref2);
+ }
+
+ }
+ return 0;
+}
+
+/*
+ * add all currently queued delayed refs from this head whose seq nr is
+ * smaller or equal that seq to the list
+ */
+static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
+ struct btrfs_key *info_key,
+ struct list_head *prefs)
+{
+ struct btrfs_delayed_extent_op *extent_op = head->extent_op;
+ struct rb_node *n = &head->node.rb_node;
+ int sgn;
+ int ret;
+
+ if (extent_op && extent_op->update_key)
+ btrfs_disk_key_to_cpu(info_key, &extent_op->key);
+
+ while ((n = rb_prev(n))) {
+ struct btrfs_delayed_ref_node *node;
+ node = rb_entry(n, struct btrfs_delayed_ref_node,
+ rb_node);
+ if (node->bytenr != head->node.bytenr)
+ break;
+ WARN_ON(node->is_head);
+
+ if (node->seq > seq)
+ continue;
+
+ switch (node->action) {
+ case BTRFS_ADD_DELAYED_EXTENT:
+ case BTRFS_UPDATE_DELAYED_HEAD:
+ WARN_ON(1);
+ continue;
+ case BTRFS_ADD_DELAYED_REF:
+ sgn = 1;
+ break;
+ case BTRFS_DROP_DELAYED_REF:
+ sgn = -1;
+ break;
+ default:
+ BUG_ON(1);
+ }
+ switch (node->type) {
+ case BTRFS_TREE_BLOCK_REF_KEY: {
+ struct btrfs_delayed_tree_ref *ref;
+
+ ref = btrfs_delayed_node_to_tree_ref(node);
+ ret = __add_prelim_ref(prefs, ref->root, info_key,
+ ref->level + 1, 0, node->bytenr,
+ node->ref_mod * sgn);
+ break;
+ }
+ case BTRFS_SHARED_BLOCK_REF_KEY: {
+ struct btrfs_delayed_tree_ref *ref;
+
+ ref = btrfs_delayed_node_to_tree_ref(node);
+ ret = __add_prelim_ref(prefs, ref->root, info_key,
+ ref->level + 1, ref->parent,
+ node->bytenr,
+ node->ref_mod * sgn);
+ break;
+ }
+ case BTRFS_EXTENT_DATA_REF_KEY: {
+ struct btrfs_delayed_data_ref *ref;
+ struct btrfs_key key;
+
+ ref = btrfs_delayed_node_to_data_ref(node);
+
+ key.objectid = ref->objectid;
+ key.type = BTRFS_EXTENT_DATA_KEY;
+ key.offset = ref->offset;
+ ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0,
+ node->bytenr,
+ node->ref_mod * sgn);
+ break;
+ }
+ case BTRFS_SHARED_DATA_REF_KEY: {
+ struct btrfs_delayed_data_ref *ref;
+ struct btrfs_key key;
+
+ ref = btrfs_delayed_node_to_data_ref(node);
+
+ key.objectid = ref->objectid;
+ key.type = BTRFS_EXTENT_DATA_KEY;
+ key.offset = ref->offset;
+ ret = __add_prelim_ref(prefs, ref->root, &key, 0,
+ ref->parent, node->bytenr,
+ node->ref_mod * sgn);
+ break;
+ }
+ default:
+ WARN_ON(1);
+ }
+ BUG_ON(ret);
+ }
+
+ return 0;
+}
+
+/*
+ * add all inline backrefs for bytenr to the list
+ */
+static int __add_inline_refs(struct btrfs_fs_info *fs_info,
+ struct btrfs_path *path, u64 bytenr,
+ struct btrfs_key *info_key, int *info_level,
+ struct list_head *prefs)
+{
+ int ret;
+ int slot;
+ struct extent_buffer *leaf;
+ struct btrfs_key key;
+ unsigned long ptr;
+ unsigned long end;
+ struct btrfs_extent_item *ei;
+ u64 flags;
+ u64 item_size;
+
+ /*
+ * enumerate all inline refs
+ */
+ leaf = path->nodes[0];
+ slot = path->slots[0] - 1;
+
+ item_size = btrfs_item_size_nr(leaf, slot);
+ BUG_ON(item_size < sizeof(*ei));
+
+ ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
+ flags = btrfs_extent_flags(leaf, ei);
+
+ ptr = (unsigned long)(ei + 1);
+ end = (unsigned long)ei + item_size;
+
+ if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
+ struct btrfs_tree_block_info *info;
+ struct btrfs_disk_key disk_key;
+
+ info = (struct btrfs_tree_block_info *)ptr;
+ *info_level = btrfs_tree_block_level(leaf, info);
+ btrfs_tree_block_key(leaf, info, &disk_key);
+ btrfs_disk_key_to_cpu(info_key, &disk_key);
+ ptr += sizeof(struct btrfs_tree_block_info);
+ BUG_ON(ptr > end);
+ } else {
+ BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
+ }
+
+ while (ptr < end) {
+ struct btrfs_extent_inline_ref *iref;
+ u64 offset;
+ int type;
+
+ iref = (struct btrfs_extent_inline_ref *)ptr;
+ type = btrfs_extent_inline_ref_type(leaf, iref);
+ offset = btrfs_extent_inline_ref_offset(leaf, iref);
+
+ switch (type) {
+ case BTRFS_SHARED_BLOCK_REF_KEY:
+ ret = __add_prelim_ref(prefs, 0, info_key,
+ *info_level + 1, offset,
+ bytenr, 1);
+ break;
+ case BTRFS_SHARED_DATA_REF_KEY: {
+ struct btrfs_shared_data_ref *sdref;
+ int count;
+
+ sdref = (struct btrfs_shared_data_ref *)(iref + 1);
+ count = btrfs_shared_data_ref_count(leaf, sdref);
+ ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
+ bytenr, count);
+ break;
+ }
+ case BTRFS_TREE_BLOCK_REF_KEY:
+ ret = __add_prelim_ref(prefs, offset, info_key,
+ *info_level + 1, 0, bytenr, 1);
+ break;
+ case BTRFS_EXTENT_DATA_REF_KEY: {
+ struct btrfs_extent_data_ref *dref;
+ int count;
+ u64 root;
+
+ dref = (struct btrfs_extent_data_ref *)(&iref->offset);
+ count = btrfs_extent_data_ref_count(leaf, dref);
+ key.objectid = btrfs_extent_data_ref_objectid(leaf,
+ dref);
+ key.type = BTRFS_EXTENT_DATA_KEY;
+ key.offset = btrfs_extent_data_ref_offset(leaf, dref);
+ root = btrfs_extent_data_ref_root(leaf, dref);
+ ret = __add_prelim_ref(prefs, root, &key, 0, 0, bytenr,
+ count);
+ break;
+ }
+ default:
+ WARN_ON(1);
+ }
+ BUG_ON(ret);
+ ptr += btrfs_extent_inline_ref_size(type);
+ }
+
+ return 0;
+}
+
+/*
+ * add all non-inline backrefs for bytenr to the list
+ */
+static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
+ struct btrfs_path *path, u64 bytenr,
+ struct btrfs_key *info_key, int info_level,
+ struct list_head *prefs)
+{
+ struct btrfs_root *extent_root = fs_info->extent_root;
+ int ret;
+ int slot;
+ struct extent_buffer *leaf;
+ struct btrfs_key key;
+
+ while (1) {
+ ret = btrfs_next_item(extent_root, path);
+ if (ret < 0)
+ break;
+ if (ret) {
+ ret = 0;
+ break;
+ }
+
+ slot = path->slots[0];
+ leaf = path->nodes[0];
+ btrfs_item_key_to_cpu(leaf, &key, slot);
+
+ if (key.objectid != bytenr)
+ break;
+ if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
+ continue;
+ if (key.type > BTRFS_SHARED_DATA_REF_KEY)
+ break;
+
+ switch (key.type) {
+ case BTRFS_SHARED_BLOCK_REF_KEY:
+ ret = __add_prelim_ref(prefs, 0, info_key,
+ info_level + 1, key.offset,
+ bytenr, 1);
+ break;
+ case BTRFS_SHARED_DATA_REF_KEY: {
+ struct btrfs_shared_data_ref *sdref;
+ int count;
+
+ sdref = btrfs_item_ptr(leaf, slot,
+ struct btrfs_shared_data_ref);
+ count = btrfs_shared_data_ref_count(leaf, sdref);
+ ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
+ bytenr, count);
+ break;
+ }
+ case BTRFS_TREE_BLOCK_REF_KEY:
+ ret = __add_prelim_ref(prefs, key.offset, info_key,
+ info_level + 1, 0, bytenr, 1);
+ break;
+ case BTRFS_EXTENT_DATA_REF_KEY: {
+ struct btrfs_extent_data_ref *dref;
+ int count;
+ u64 root;
+
+ dref = btrfs_item_ptr(leaf, slot,
+ struct btrfs_extent_data_ref);
+ count = btrfs_extent_data_ref_count(leaf, dref);
+ key.objectid = btrfs_extent_data_ref_objectid(leaf,
+ dref);
+ key.type = BTRFS_EXTENT_DATA_KEY;
+ key.offset = btrfs_extent_data_ref_offset(leaf, dref);
+ root = btrfs_extent_data_ref_root(leaf, dref);
+ ret = __add_prelim_ref(prefs, root, &key, 0, 0,
+ bytenr, count);
+ break;
+ }
+ default:
+ WARN_ON(1);
+ }
+ BUG_ON(ret);
+ }
+
+ return ret;
+}
+
+/*
+ * this adds all existing backrefs (inline backrefs, backrefs and delayed
+ * refs) for the given bytenr to the refs list, merges duplicates and resolves
+ * indirect refs to their parent bytenr.
+ * When roots are found, they're added to the roots list
+ *
+ * FIXME some caching might speed things up
+ */
+static int find_parent_nodes(struct btrfs_trans_handle *trans,
+ struct btrfs_fs_info *fs_info, u64 bytenr,
+ u64 seq, struct ulist *refs, struct ulist *roots)
+{
+ struct btrfs_key key;
+ struct btrfs_path *path;
+ struct btrfs_key info_key = { 0 };
+ struct btrfs_delayed_ref_root *delayed_refs = NULL;
+ struct btrfs_delayed_ref_head *head = NULL;
+ int info_level = 0;
+ int ret;
+ struct list_head prefs_delayed;
+ struct list_head prefs;
+ struct __prelim_ref *ref;
+
+ INIT_LIST_HEAD(&prefs);
+ INIT_LIST_HEAD(&prefs_delayed);
+
+ key.objectid = bytenr;
+ key.type = BTRFS_EXTENT_ITEM_KEY;
+ key.offset = (u64)-1;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ /*
+ * grab both a lock on the path and a lock on the delayed ref head.
+ * We need both to get a consistent picture of how the refs look
+ * at a specified point in time
+ */
+again:
+ ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
+ if (ret < 0)
+ goto out;
+ BUG_ON(ret == 0);
+
+ /*
+ * look if there are updates for this ref queued and lock the head
+ */
+ delayed_refs = &trans->transaction->delayed_refs;
+ spin_lock(&delayed_refs->lock);
+ head = btrfs_find_delayed_ref_head(trans, bytenr);
+ if (head) {
+ if (!mutex_trylock(&head->mutex)) {
+ atomic_inc(&head->node.refs);
+ spin_unlock(&delayed_refs->lock);
+
+ btrfs_release_path(path);
+
+ /*
+ * Mutex was contended, block until it's
+ * released and try again
+ */
+ mutex_lock(&head->mutex);
+ mutex_unlock(&head->mutex);
+ btrfs_put_delayed_ref(&head->node);
+ goto again;
+ }
+ ret = __add_delayed_refs(head, seq, &info_key, &prefs_delayed);
+ if (ret)
+ goto out;
+ }
+ spin_unlock(&delayed_refs->lock);
+
+ if (path->slots[0]) {
+ struct extent_buffer *leaf;
+ int slot;
+
+ leaf = path->nodes[0];
+ slot = path->slots[0] - 1;
+ btrfs_item_key_to_cpu(leaf, &key, slot);
+ if (key.objectid == bytenr &&
+ key.type == BTRFS_EXTENT_ITEM_KEY) {
+ ret = __add_inline_refs(fs_info, path, bytenr,
+ &info_key, &info_level, &prefs);
+ if (ret)
+ goto out;
+ ret = __add_keyed_refs(fs_info, path, bytenr, &info_key,
+ info_level, &prefs);
+ if (ret)
+ goto out;
+ }
+ }
+ btrfs_release_path(path);
+
+ /*
+ * when adding the delayed refs above, the info_key might not have
+ * been known yet. Go over the list and replace the missing keys
+ */
+ list_for_each_entry(ref, &prefs_delayed, list) {
+ if ((ref->key.offset | ref->key.type | ref->key.objectid) == 0)
+ memcpy(&ref->key, &info_key, sizeof(ref->key));
+ }
+ list_splice_init(&prefs_delayed, &prefs);
+
+ ret = __merge_refs(&prefs, 1);
+ if (ret)
+ goto out;
+
+ ret = __resolve_indirect_refs(fs_info, &prefs);
+ if (ret)
+ goto out;
+
+ ret = __merge_refs(&prefs, 2);
+ if (ret)
+ goto out;
+
+ while (!list_empty(&prefs)) {
+ ref = list_first_entry(&prefs, struct __prelim_ref, list);
+ list_del(&ref->list);
+ if (ref->count < 0)
+ WARN_ON(1);
+ if (ref->count && ref->root_id && ref->parent == 0) {
+ /* no parent == root of tree */
+ ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
+ BUG_ON(ret < 0);
+ }
+ if (ref->count && ref->parent) {
+ ret = ulist_add(refs, ref->parent, 0, GFP_NOFS);
+ BUG_ON(ret < 0);
+ }
+ kfree(ref);
+ }
+
+out:
+ if (head)
+ mutex_unlock(&head->mutex);
+ btrfs_free_path(path);
+ while (!list_empty(&prefs)) {
+ ref = list_first_entry(&prefs, struct __prelim_ref, list);
+ list_del(&ref->list);
+ kfree(ref);
+ }
+ while (!list_empty(&prefs_delayed)) {
+ ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
+ list);
+ list_del(&ref->list);
+ kfree(ref);
+ }
+
+ return ret;
+}
+
+/*
+ * Finds all leafs with a reference to the specified combination of bytenr and
+ * offset. key_list_head will point to a list of corresponding keys (caller must
+ * free each list element). The leafs will be stored in the leafs ulist, which
+ * must be freed with ulist_free.
+ *
+ * returns 0 on success, <0 on error
+ */
+static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
+ struct btrfs_fs_info *fs_info, u64 bytenr,
+ u64 num_bytes, u64 seq, struct ulist **leafs)
+{
+ struct ulist *tmp;
+ int ret;
+
+ tmp = ulist_alloc(GFP_NOFS);
+ if (!tmp)
+ return -ENOMEM;
+ *leafs = ulist_alloc(GFP_NOFS);
+ if (!*leafs) {
+ ulist_free(tmp);
+ return -ENOMEM;
+ }
+
+ ret = find_parent_nodes(trans, fs_info, bytenr, seq, *leafs, tmp);
+ ulist_free(tmp);
+
+ if (ret < 0 && ret != -ENOENT) {
+ ulist_free(*leafs);
+ return ret;
+ }
+
+ return 0;
+}
+
+/*
+ * walk all backrefs for a given extent to find all roots that reference this
+ * extent. Walking a backref means finding all extents that reference this
+ * extent and in turn walk the backrefs of those, too. Naturally this is a
+ * recursive process, but here it is implemented in an iterative fashion: We
+ * find all referencing extents for the extent in question and put them on a
+ * list. In turn, we find all referencing extents for those, further appending
+ * to the list. The way we iterate the list allows adding more elements after
+ * the current while iterating. The process stops when we reach the end of the
+ * list. Found roots are added to the roots list.
+ *
+ * returns 0 on success, < 0 on error.
+ */
+int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
+ struct btrfs_fs_info *fs_info, u64 bytenr,
+ u64 num_bytes, u64 seq, struct ulist **roots)
+{
+ struct ulist *tmp;
+ struct ulist_node *node = NULL;
+ int ret;
+
+ tmp = ulist_alloc(GFP_NOFS);
+ if (!tmp)
+ return -ENOMEM;
+ *roots = ulist_alloc(GFP_NOFS);
+ if (!*roots) {
+ ulist_free(tmp);
+ return -ENOMEM;
+ }
+
+ while (1) {
+ ret = find_parent_nodes(trans, fs_info, bytenr, seq,
+ tmp, *roots);
+ if (ret < 0 && ret != -ENOENT) {
+ ulist_free(tmp);
+ ulist_free(*roots);
+ return ret;
+ }
+ node = ulist_next(tmp, node);
+ if (!node)
+ break;
+ bytenr = node->val;
+ }
+
+ ulist_free(tmp);
+ return 0;
+}
+
static int __inode_info(u64 inum, u64 ioff, u8 key_type,
struct btrfs_root *fs_root, struct btrfs_path *path,
btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
if (found_key->type != BTRFS_EXTENT_ITEM_KEY ||
found_key->objectid > logical ||
- found_key->objectid + found_key->offset <= logical)
+ found_key->objectid + found_key->offset <= logical) {
+ pr_debug("logical %llu is not within any extent\n",
+ (unsigned long long)logical);
return -ENOENT;
+ }
eb = path->nodes[0];
item_size = btrfs_item_size_nr(eb, path->slots[0]);
ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
flags = btrfs_extent_flags(eb, ei);
+ pr_debug("logical %llu is at position %llu within the extent (%llu "
+ "EXTENT_ITEM %llu) flags %#llx size %u\n",
+ (unsigned long long)logical,
+ (unsigned long long)(logical - found_key->objectid),
+ (unsigned long long)found_key->objectid,
+ (unsigned long long)found_key->offset,
+ (unsigned long long)flags, item_size);
if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
return BTRFS_EXTENT_FLAG_TREE_BLOCK;
if (flags & BTRFS_EXTENT_FLAG_DATA)
return 0;
}
-static int __data_list_add(struct list_head *head, u64 inum,
- u64 extent_data_item_offset, u64 root)
-{
- struct __data_ref *ref;
-
- ref = kmalloc(sizeof(*ref), GFP_NOFS);
- if (!ref)
- return -ENOMEM;
-
- ref->inum = inum;
- ref->extent_data_item_offset = extent_data_item_offset;
- ref->root = root;
- list_add_tail(&ref->list, head);
-
- return 0;
-}
-
-static int __data_list_add_eb(struct list_head *head, struct extent_buffer *eb,
- struct btrfs_extent_data_ref *dref)
-{
- return __data_list_add(head, btrfs_extent_data_ref_objectid(eb, dref),
- btrfs_extent_data_ref_offset(eb, dref),
- btrfs_extent_data_ref_root(eb, dref));
-}
-
-static int __shared_list_add(struct list_head *head, u64 disk_byte)
-{
- struct __shared_ref *ref;
-
- ref = kmalloc(sizeof(*ref), GFP_NOFS);
- if (!ref)
- return -ENOMEM;
-
- ref->disk_byte = disk_byte;
- list_add_tail(&ref->list, head);
-
- return 0;
-}
-
-static int __iter_shared_inline_ref_inodes(struct btrfs_fs_info *fs_info,
- u64 logical, u64 inum,
- u64 extent_data_item_offset,
- u64 extent_offset,
- struct btrfs_path *path,
- struct list_head *data_refs,
- iterate_extent_inodes_t *iterate,
- void *ctx)
-{
- u64 ref_root;
- u32 item_size;
- struct btrfs_key key;
- struct extent_buffer *eb;
- struct btrfs_extent_item *ei;
- struct btrfs_extent_inline_ref *eiref;
- struct __data_ref *ref;
- int ret;
- int type;
- int last;
- unsigned long ptr = 0;
-
- WARN_ON(!list_empty(data_refs));
- ret = extent_from_logical(fs_info, logical, path, &key);
- if (ret & BTRFS_EXTENT_FLAG_DATA)
- ret = -EIO;
- if (ret < 0)
- goto out;
-
- eb = path->nodes[0];
- ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
- item_size = btrfs_item_size_nr(eb, path->slots[0]);
-
- ret = 0;
- ref_root = 0;
- /*
- * as done in iterate_extent_inodes, we first build a list of refs to
- * iterate, then free the path and then iterate them to avoid deadlocks.
- */
- do {
- last = __get_extent_inline_ref(&ptr, eb, ei, item_size,
- &eiref, &type);
- if (last < 0) {
- ret = last;
- goto out;
- }
- if (type == BTRFS_TREE_BLOCK_REF_KEY ||
- type == BTRFS_SHARED_BLOCK_REF_KEY) {
- ref_root = btrfs_extent_inline_ref_offset(eb, eiref);
- ret = __data_list_add(data_refs, inum,
- extent_data_item_offset,
- ref_root);
- }
- } while (!ret && !last);
-
- btrfs_release_path(path);
-
- if (ref_root == 0) {
- printk(KERN_ERR "btrfs: failed to find tree block ref "
- "for shared data backref %llu\n", logical);
- WARN_ON(1);
- ret = -EIO;
- }
-
-out:
- while (!list_empty(data_refs)) {
- ref = list_first_entry(data_refs, struct __data_ref, list);
- list_del(&ref->list);
- if (!ret)
- ret = iterate(ref->inum, extent_offset +
- ref->extent_data_item_offset,
- ref->root, ctx);
- kfree(ref);
- }
-
- return ret;
-}
-
-static int __iter_shared_inline_ref(struct btrfs_fs_info *fs_info,
- u64 logical, u64 orig_extent_item_objectid,
- u64 extent_offset, struct btrfs_path *path,
- struct list_head *data_refs,
- iterate_extent_inodes_t *iterate,
- void *ctx)
+static int iterate_leaf_refs(struct btrfs_fs_info *fs_info,
+ struct btrfs_path *path, u64 logical,
+ u64 orig_extent_item_objectid,
+ u64 extent_item_pos, u64 root,
+ iterate_extent_inodes_t *iterate, void *ctx)
{
u64 disk_byte;
struct btrfs_key key;
struct extent_buffer *eb;
int slot;
int nritems;
- int ret;
- int found = 0;
+ int ret = 0;
+ int extent_type;
+ u64 data_offset;
+ u64 data_len;
eb = read_tree_block(fs_info->tree_root, logical,
fs_info->tree_root->leafsize, 0);
if (key.type != BTRFS_EXTENT_DATA_KEY)
continue;
fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
- if (!fi) {
- free_extent_buffer(eb);
- return -EIO;
- }
+ extent_type = btrfs_file_extent_type(eb, fi);
+ if (extent_type == BTRFS_FILE_EXTENT_INLINE)
+ continue;
+ /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
- if (disk_byte != orig_extent_item_objectid) {
- if (found)
- break;
- else
- continue;
- }
- ++found;
- ret = __iter_shared_inline_ref_inodes(fs_info, logical,
- key.objectid,
- key.offset,
- extent_offset, path,
- data_refs,
- iterate, ctx);
- if (ret)
- break;
- }
+ if (disk_byte != orig_extent_item_objectid)
+ continue;
- if (!found) {
- printk(KERN_ERR "btrfs: failed to follow shared data backref "
- "to parent %llu\n", logical);
- WARN_ON(1);
- ret = -EIO;
+ data_offset = btrfs_file_extent_offset(eb, fi);
+ data_len = btrfs_file_extent_num_bytes(eb, fi);
+
+ if (extent_item_pos < data_offset ||
+ extent_item_pos >= data_offset + data_len)
+ continue;
+
+ pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
+ "root %llu\n", orig_extent_item_objectid,
+ key.objectid, key.offset, root);
+ ret = iterate(key.objectid,
+ key.offset + (extent_item_pos - data_offset),
+ root, ctx);
+ if (ret) {
+ pr_debug("stopping iteration because ret=%d\n", ret);
+ break;
+ }
}
free_extent_buffer(eb);
+
return ret;
}
/*
* calls iterate() for every inode that references the extent identified by
- * the given parameters. will use the path given as a parameter and return it
- * released.
+ * the given parameters.
* when the iterator function returns a non-zero value, iteration stops.
+ * path is guaranteed to be in released state when iterate() is called.
*/
int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
struct btrfs_path *path,
- u64 extent_item_objectid,
- u64 extent_offset,
+ u64 extent_item_objectid, u64 extent_item_pos,
iterate_extent_inodes_t *iterate, void *ctx)
{
- unsigned long ptr = 0;
- int last;
int ret;
- int type;
- u64 logical;
- u32 item_size;
- struct btrfs_extent_inline_ref *eiref;
- struct btrfs_extent_data_ref *dref;
- struct extent_buffer *eb;
- struct btrfs_extent_item *ei;
- struct btrfs_key key;
struct list_head data_refs = LIST_HEAD_INIT(data_refs);
struct list_head shared_refs = LIST_HEAD_INIT(shared_refs);
- struct __data_ref *ref_d;
- struct __shared_ref *ref_s;
-
- eb = path->nodes[0];
- ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
- item_size = btrfs_item_size_nr(eb, path->slots[0]);
-
- /* first we iterate the inline refs, ... */
- do {
- last = __get_extent_inline_ref(&ptr, eb, ei, item_size,
- &eiref, &type);
- if (last == -ENOENT) {
- ret = 0;
- break;
- }
- if (last < 0) {
- ret = last;
- break;
- }
+ struct btrfs_trans_handle *trans;
+ struct ulist *refs;
+ struct ulist *roots;
+ struct ulist_node *ref_node = NULL;
+ struct ulist_node *root_node = NULL;
+ struct seq_list seq_elem;
+ struct btrfs_delayed_ref_root *delayed_refs;
+
+ trans = btrfs_join_transaction(fs_info->extent_root);
+ if (IS_ERR(trans))
+ return PTR_ERR(trans);
+
+ pr_debug("resolving all inodes for extent %llu\n",
+ extent_item_objectid);
+
+ delayed_refs = &trans->transaction->delayed_refs;
+ spin_lock(&delayed_refs->lock);
+ btrfs_get_delayed_seq(delayed_refs, &seq_elem);
+ spin_unlock(&delayed_refs->lock);
+
+ ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
+ extent_item_pos, seq_elem.seq,
+ &refs);
- if (type == BTRFS_EXTENT_DATA_REF_KEY) {
- dref = (struct btrfs_extent_data_ref *)(&eiref->offset);
- ret = __data_list_add_eb(&data_refs, eb, dref);
- } else if (type == BTRFS_SHARED_DATA_REF_KEY) {
- logical = btrfs_extent_inline_ref_offset(eb, eiref);
- ret = __shared_list_add(&shared_refs, logical);
- }
- } while (!ret && !last);
+ if (ret)
+ goto out;
- /* ... then we proceed to in-tree references and ... */
- while (!ret) {
- ++path->slots[0];
- if (path->slots[0] > btrfs_header_nritems(eb)) {
- ret = btrfs_next_leaf(fs_info->extent_root, path);
- if (ret) {
- if (ret == 1)
- ret = 0; /* we're done */
- break;
- }
- eb = path->nodes[0];
- }
- btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
- if (key.objectid != extent_item_objectid)
+ while (!ret && (ref_node = ulist_next(refs, ref_node))) {
+ ret = btrfs_find_all_roots(trans, fs_info, ref_node->val, -1,
+ seq_elem.seq, &roots);
+ if (ret)
break;
- if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
- dref = btrfs_item_ptr(eb, path->slots[0],
- struct btrfs_extent_data_ref);
- ret = __data_list_add_eb(&data_refs, eb, dref);
- } else if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
- ret = __shared_list_add(&shared_refs, key.offset);
+ while (!ret && (root_node = ulist_next(roots, root_node))) {
+ pr_debug("root %llu references leaf %llu\n",
+ root_node->val, ref_node->val);
+ ret = iterate_leaf_refs(fs_info, path, ref_node->val,
+ extent_item_objectid,
+ extent_item_pos, root_node->val,
+ iterate, ctx);
}
}
- btrfs_release_path(path);
-
- /*
- * ... only at the very end we can process the refs we found. this is
- * because the iterator function we call is allowed to make tree lookups
- * and we have to avoid deadlocks. additionally, we need more tree
- * lookups ourselves for shared data refs.
- */
- while (!list_empty(&data_refs)) {
- ref_d = list_first_entry(&data_refs, struct __data_ref, list);
- list_del(&ref_d->list);
- if (!ret)
- ret = iterate(ref_d->inum, extent_offset +
- ref_d->extent_data_item_offset,
- ref_d->root, ctx);
- kfree(ref_d);
- }
-
- while (!list_empty(&shared_refs)) {
- ref_s = list_first_entry(&shared_refs, struct __shared_ref,
- list);
- list_del(&ref_s->list);
- if (!ret)
- ret = __iter_shared_inline_ref(fs_info,
- ref_s->disk_byte,
- extent_item_objectid,
- extent_offset, path,
- &data_refs,
- iterate, ctx);
- kfree(ref_s);
- }
-
+ ulist_free(refs);
+ ulist_free(roots);
+out:
+ btrfs_put_delayed_seq(delayed_refs, &seq_elem);
+ btrfs_end_transaction(trans, fs_info->extent_root);
return ret;
}
iterate_extent_inodes_t *iterate, void *ctx)
{
int ret;
- u64 offset;
+ u64 extent_item_pos;
struct btrfs_key found_key;
ret = extent_from_logical(fs_info, logical, path,
&found_key);
+ btrfs_release_path(path);
if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK)
ret = -EINVAL;
if (ret < 0)
return ret;
- offset = logical - found_key.objectid;
+ extent_item_pos = logical - found_key.objectid;
ret = iterate_extent_inodes(fs_info, path, found_key.objectid,
- offset, iterate, ctx);
+ extent_item_pos, iterate, ctx);
return ret;
}
for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
name_len = btrfs_inode_ref_name_len(eb, iref);
/* path must be released before calling iterate()! */
+ pr_debug("following ref at offset %u for inode %llu in "
+ "tree %llu\n", cur,
+ (unsigned long long)found_key.objectid,
+ (unsigned long long)fs_root->objectid);
ret = iterate(parent, iref, eb, ctx);
if (ret) {
free_extent_buffer(eb);
return PTR_ERR(fspath);
if (fspath > fspath_min) {
+ pr_debug("path resolved: %s\n", fspath);
ipath->fspath->val[i] = (u64)(unsigned long)fspath;
++ipath->fspath->elem_cnt;
ipath->fspath->bytes_left = fspath - fspath_min;
} else {
+ pr_debug("missed path, not enough space. missing bytes: %lu, "
+ "constructed so far: %s\n",
+ (unsigned long)(fspath_min - fspath), fspath_min);
++ipath->fspath->elem_missed;
ipath->fspath->bytes_missing += fspath_min - fspath;
ipath->fspath->bytes_left = 0;
#define __BTRFS_BACKREF__
#include "ioctl.h"
+#include "ulist.h"
struct inode_fs_paths {
struct btrfs_path *btrfs_path;
int paths_from_inode(u64 inum, struct inode_fs_paths *ipath);
+int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
+ struct btrfs_fs_info *fs_info, u64 bytenr,
+ u64 num_bytes, u64 seq, struct ulist **roots);
+
struct btrfs_data_container *init_data_container(u32 total_bytes);
struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
struct btrfs_path *path);
cow = btrfs_alloc_free_block(trans, root, buf->len, 0,
new_root_objectid, &disk_key, level,
- buf->start, 0);
+ buf->start, 0, 1);
if (IS_ERR(cow))
return PTR_ERR(cow);
WARN_ON(btrfs_header_generation(buf) > trans->transid);
if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
- ret = btrfs_inc_ref(trans, root, cow, 1);
+ ret = btrfs_inc_ref(trans, root, cow, 1, 1);
else
- ret = btrfs_inc_ref(trans, root, cow, 0);
+ ret = btrfs_inc_ref(trans, root, cow, 0, 1);
if (ret)
return ret;
if ((owner == root->root_key.objectid ||
root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
!(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
- ret = btrfs_inc_ref(trans, root, buf, 1);
+ ret = btrfs_inc_ref(trans, root, buf, 1, 1);
BUG_ON(ret);
if (root->root_key.objectid ==
BTRFS_TREE_RELOC_OBJECTID) {
- ret = btrfs_dec_ref(trans, root, buf, 0);
+ ret = btrfs_dec_ref(trans, root, buf, 0, 1);
BUG_ON(ret);
- ret = btrfs_inc_ref(trans, root, cow, 1);
+ ret = btrfs_inc_ref(trans, root, cow, 1, 1);
BUG_ON(ret);
}
new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
if (root->root_key.objectid ==
BTRFS_TREE_RELOC_OBJECTID)
- ret = btrfs_inc_ref(trans, root, cow, 1);
+ ret = btrfs_inc_ref(trans, root, cow, 1, 1);
else
- ret = btrfs_inc_ref(trans, root, cow, 0);
+ ret = btrfs_inc_ref(trans, root, cow, 0, 1);
BUG_ON(ret);
}
if (new_flags != 0) {
if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
if (root->root_key.objectid ==
BTRFS_TREE_RELOC_OBJECTID)
- ret = btrfs_inc_ref(trans, root, cow, 1);
+ ret = btrfs_inc_ref(trans, root, cow, 1, 1);
else
- ret = btrfs_inc_ref(trans, root, cow, 0);
+ ret = btrfs_inc_ref(trans, root, cow, 0, 1);
BUG_ON(ret);
- ret = btrfs_dec_ref(trans, root, buf, 1);
+ ret = btrfs_dec_ref(trans, root, buf, 1, 1);
BUG_ON(ret);
}
clean_tree_block(trans, root, buf);
cow = btrfs_alloc_free_block(trans, root, buf->len, parent_start,
root->root_key.objectid, &disk_key,
- level, search_start, empty_size);
+ level, search_start, empty_size, 1);
if (IS_ERR(cow))
return PTR_ERR(cow);
rcu_assign_pointer(root->node, cow);
btrfs_free_tree_block(trans, root, buf, parent_start,
- last_ref);
+ last_ref, 1);
free_extent_buffer(buf);
add_root_to_dirty_list(root);
} else {
trans->transid);
btrfs_mark_buffer_dirty(parent);
btrfs_free_tree_block(trans, root, buf, parent_start,
- last_ref);
+ last_ref, 1);
}
if (unlock_orig)
btrfs_tree_unlock(buf);
free_extent_buffer(mid);
root_sub_used(root, mid->len);
- btrfs_free_tree_block(trans, root, mid, 0, 1);
+ btrfs_free_tree_block(trans, root, mid, 0, 1, 0);
/* once for the root ptr */
free_extent_buffer(mid);
return 0;
if (wret)
ret = wret;
root_sub_used(root, right->len);
- btrfs_free_tree_block(trans, root, right, 0, 1);
+ btrfs_free_tree_block(trans, root, right, 0, 1, 0);
free_extent_buffer(right);
right = NULL;
} else {
if (wret)
ret = wret;
root_sub_used(root, mid->len);
- btrfs_free_tree_block(trans, root, mid, 0, 1);
+ btrfs_free_tree_block(trans, root, mid, 0, 1, 0);
free_extent_buffer(mid);
mid = NULL;
} else {
c = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
root->root_key.objectid, &lower_key,
- level, root->node->start, 0);
+ level, root->node->start, 0, 0);
if (IS_ERR(c))
return PTR_ERR(c);
split = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
root->root_key.objectid,
- &disk_key, level, c->start, 0);
+ &disk_key, level, c->start, 0, 0);
if (IS_ERR(split))
return PTR_ERR(split);
right = btrfs_alloc_free_block(trans, root, root->leafsize, 0,
root->root_key.objectid,
- &disk_key, 0, l->start, 0);
+ &disk_key, 0, l->start, 0, 0);
if (IS_ERR(right))
return PTR_ERR(right);
root_sub_used(root, leaf->len);
- btrfs_free_tree_block(trans, root, leaf, 0, 1);
+ btrfs_free_tree_block(trans, root, leaf, 0, 1, 0);
return 0;
}
/*
struct btrfs_root *root, u32 blocksize,
u64 parent, u64 root_objectid,
struct btrfs_disk_key *key, int level,
- u64 hint, u64 empty_size);
+ u64 hint, u64 empty_size, int for_cow);
void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct extent_buffer *buf,
- u64 parent, int last_ref);
+ u64 parent, int last_ref, int for_cow);
struct extent_buffer *btrfs_init_new_buffer(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
u64 bytenr, u32 blocksize,
u64 search_end, struct btrfs_key *ins,
u64 data);
int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
- struct extent_buffer *buf, int full_backref);
+ struct extent_buffer *buf, int full_backref, int for_cow);
int btrfs_dec_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
- struct extent_buffer *buf, int full_backref);
+ struct extent_buffer *buf, int full_backref, int for_cow);
int btrfs_set_disk_extent_flags(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
u64 bytenr, u64 num_bytes, u64 flags,
int is_data);
int btrfs_free_extent(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
- u64 bytenr, u64 num_bytes, u64 parent,
- u64 root_objectid, u64 owner, u64 offset);
+ u64 bytenr, u64 num_bytes, u64 parent, u64 root_objectid,
+ u64 owner, u64 offset, int for_cow);
int btrfs_free_reserved_extent(struct btrfs_root *root, u64 start, u64 len);
int btrfs_free_and_pin_reserved_extent(struct btrfs_root *root,
int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
u64 bytenr, u64 num_bytes, u64 parent,
- u64 root_objectid, u64 owner, u64 offset);
+ u64 root_objectid, u64 owner, u64 offset, int for_cow);
int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
}
int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path);
+static inline int btrfs_next_item(struct btrfs_root *root, struct btrfs_path *p)
+{
+ ++p->slots[0];
+ if (p->slots[0] >= btrfs_header_nritems(p->nodes[0]))
+ return btrfs_next_leaf(root, p);
+ return 0;
+}
int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path);
int btrfs_leaf_free_space(struct btrfs_root *root, struct extent_buffer *leaf);
void btrfs_drop_snapshot(struct btrfs_root *root,
- struct btrfs_block_rsv *block_rsv, int update_ref);
+ struct btrfs_block_rsv *block_rsv, int update_ref,
+ int for_reloc);
int btrfs_drop_subtree(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct extent_buffer *node,
return -1;
if (ref1->type > ref2->type)
return 1;
+ /* merging of sequenced refs is not allowed */
+ if (ref1->seq < ref2->seq)
+ return -1;
+ if (ref1->seq > ref2->seq)
+ return 1;
if (ref1->type == BTRFS_TREE_BLOCK_REF_KEY ||
ref1->type == BTRFS_SHARED_BLOCK_REF_KEY) {
return comp_tree_refs(btrfs_delayed_node_to_tree_ref(ref2),
/*
* find an head entry based on bytenr. This returns the delayed ref
- * head if it was able to find one, or NULL if nothing was in that spot
+ * head if it was able to find one, or NULL if nothing was in that spot.
+ * If return_bigger is given, the next bigger entry is returned if no exact
+ * match is found.
*/
static struct btrfs_delayed_ref_node *find_ref_head(struct rb_root *root,
u64 bytenr,
- struct btrfs_delayed_ref_node **last)
+ struct btrfs_delayed_ref_node **last,
+ int return_bigger)
{
- struct rb_node *n = root->rb_node;
+ struct rb_node *n;
struct btrfs_delayed_ref_node *entry;
- int cmp;
+ int cmp = 0;
+again:
+ n = root->rb_node;
+ entry = NULL;
while (n) {
entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
WARN_ON(!entry->in_tree);
else
return entry;
}
+ if (entry && return_bigger) {
+ if (cmp > 0) {
+ n = rb_next(&entry->rb_node);
+ if (!n)
+ n = rb_first(root);
+ entry = rb_entry(n, struct btrfs_delayed_ref_node,
+ rb_node);
+ bytenr = entry->bytenr;
+ return_bigger = 0;
+ goto again;
+ }
+ return entry;
+ }
return NULL;
}
return 0;
}
+int btrfs_check_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs,
+ u64 seq)
+{
+ struct seq_list *elem;
+
+ assert_spin_locked(&delayed_refs->lock);
+ if (list_empty(&delayed_refs->seq_head))
+ return 0;
+
+ elem = list_first_entry(&delayed_refs->seq_head, struct seq_list, list);
+ if (seq >= elem->seq) {
+ pr_debug("holding back delayed_ref %llu, lowest is %llu (%p)\n",
+ seq, elem->seq, delayed_refs);
+ return 1;
+ }
+ return 0;
+}
+
int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
struct list_head *cluster, u64 start)
{
node = rb_first(&delayed_refs->root);
} else {
ref = NULL;
- find_ref_head(&delayed_refs->root, start, &ref);
+ find_ref_head(&delayed_refs->root, start + 1, &ref, 1);
if (ref) {
- struct btrfs_delayed_ref_node *tmp;
-
- node = rb_prev(&ref->rb_node);
- while (node) {
- tmp = rb_entry(node,
- struct btrfs_delayed_ref_node,
- rb_node);
- if (tmp->bytenr < start)
- break;
- ref = tmp;
- node = rb_prev(&ref->rb_node);
- }
node = &ref->rb_node;
} else
node = rb_first(&delayed_refs->root);
* this does all the dirty work in terms of maintaining the correct
* overall modification count.
*/
-static noinline int add_delayed_ref_head(struct btrfs_trans_handle *trans,
+static noinline int add_delayed_ref_head(struct btrfs_fs_info *fs_info,
+ struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_node *ref,
u64 bytenr, u64 num_bytes,
int action, int is_data)
ref->action = 0;
ref->is_head = 1;
ref->in_tree = 1;
+ ref->seq = 0;
head_ref = btrfs_delayed_node_to_head(ref);
head_ref->must_insert_reserved = must_insert_reserved;
/*
* helper to insert a delayed tree ref into the rbtree.
*/
-static noinline int add_delayed_tree_ref(struct btrfs_trans_handle *trans,
+static noinline int add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
+ struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_node *ref,
u64 bytenr, u64 num_bytes, u64 parent,
- u64 ref_root, int level, int action)
+ u64 ref_root, int level, int action,
+ int for_cow)
{
struct btrfs_delayed_ref_node *existing;
struct btrfs_delayed_tree_ref *full_ref;
struct btrfs_delayed_ref_root *delayed_refs;
+ u64 seq = 0;
if (action == BTRFS_ADD_DELAYED_EXTENT)
action = BTRFS_ADD_DELAYED_REF;
ref->is_head = 0;
ref->in_tree = 1;
+ if (need_ref_seq(for_cow, ref_root))
+ seq = inc_delayed_seq(delayed_refs);
+ ref->seq = seq;
+
full_ref = btrfs_delayed_node_to_tree_ref(ref);
- if (parent) {
- full_ref->parent = parent;
+ full_ref->parent = parent;
+ full_ref->root = ref_root;
+ if (parent)
ref->type = BTRFS_SHARED_BLOCK_REF_KEY;
- } else {
- full_ref->root = ref_root;
+ else
ref->type = BTRFS_TREE_BLOCK_REF_KEY;
- }
full_ref->level = level;
trace_btrfs_delayed_tree_ref(ref, full_ref, action);
/*
* helper to insert a delayed data ref into the rbtree.
*/
-static noinline int add_delayed_data_ref(struct btrfs_trans_handle *trans,
+static noinline int add_delayed_data_ref(struct btrfs_fs_info *fs_info,
+ struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_node *ref,
u64 bytenr, u64 num_bytes, u64 parent,
u64 ref_root, u64 owner, u64 offset,
- int action)
+ int action, int for_cow)
{
struct btrfs_delayed_ref_node *existing;
struct btrfs_delayed_data_ref *full_ref;
struct btrfs_delayed_ref_root *delayed_refs;
+ u64 seq = 0;
if (action == BTRFS_ADD_DELAYED_EXTENT)
action = BTRFS_ADD_DELAYED_REF;
ref->is_head = 0;
ref->in_tree = 1;
+ if (need_ref_seq(for_cow, ref_root))
+ seq = inc_delayed_seq(delayed_refs);
+ ref->seq = seq;
+
full_ref = btrfs_delayed_node_to_data_ref(ref);
- if (parent) {
- full_ref->parent = parent;
+ full_ref->parent = parent;
+ full_ref->root = ref_root;
+ if (parent)
ref->type = BTRFS_SHARED_DATA_REF_KEY;
- } else {
- full_ref->root = ref_root;
+ else
ref->type = BTRFS_EXTENT_DATA_REF_KEY;
- }
+
full_ref->objectid = owner;
full_ref->offset = offset;
* to make sure the delayed ref is eventually processed before this
* transaction commits.
*/
-int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
+int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
+ struct btrfs_trans_handle *trans,
u64 bytenr, u64 num_bytes, u64 parent,
u64 ref_root, int level, int action,
- struct btrfs_delayed_extent_op *extent_op)
+ struct btrfs_delayed_extent_op *extent_op,
+ int for_cow)
{
struct btrfs_delayed_tree_ref *ref;
struct btrfs_delayed_ref_head *head_ref;
* insert both the head node and the new ref without dropping
* the spin lock
*/
- ret = add_delayed_ref_head(trans, &head_ref->node, bytenr, num_bytes,
- action, 0);
+ ret = add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
+ num_bytes, action, 0);
BUG_ON(ret);
- ret = add_delayed_tree_ref(trans, &ref->node, bytenr, num_bytes,
- parent, ref_root, level, action);
+ ret = add_delayed_tree_ref(fs_info, trans, &ref->node, bytenr,
+ num_bytes, parent, ref_root, level, action,
+ for_cow);
BUG_ON(ret);
+ if (!need_ref_seq(for_cow, ref_root) &&
+ waitqueue_active(&delayed_refs->seq_wait))
+ wake_up(&delayed_refs->seq_wait);
spin_unlock(&delayed_refs->lock);
return 0;
}
/*
* add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
*/
-int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
+int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
+ struct btrfs_trans_handle *trans,
u64 bytenr, u64 num_bytes,
u64 parent, u64 ref_root,
u64 owner, u64 offset, int action,
- struct btrfs_delayed_extent_op *extent_op)
+ struct btrfs_delayed_extent_op *extent_op,
+ int for_cow)
{
struct btrfs_delayed_data_ref *ref;
struct btrfs_delayed_ref_head *head_ref;
* insert both the head node and the new ref without dropping
* the spin lock
*/
- ret = add_delayed_ref_head(trans, &head_ref->node, bytenr, num_bytes,
- action, 1);
+ ret = add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
+ num_bytes, action, 1);
BUG_ON(ret);
- ret = add_delayed_data_ref(trans, &ref->node, bytenr, num_bytes,
- parent, ref_root, owner, offset, action);
+ ret = add_delayed_data_ref(fs_info, trans, &ref->node, bytenr,
+ num_bytes, parent, ref_root, owner, offset,
+ action, for_cow);
BUG_ON(ret);
+ if (!need_ref_seq(for_cow, ref_root) &&
+ waitqueue_active(&delayed_refs->seq_wait))
+ wake_up(&delayed_refs->seq_wait);
spin_unlock(&delayed_refs->lock);
return 0;
}
-int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
+int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
+ struct btrfs_trans_handle *trans,
u64 bytenr, u64 num_bytes,
struct btrfs_delayed_extent_op *extent_op)
{
delayed_refs = &trans->transaction->delayed_refs;
spin_lock(&delayed_refs->lock);
- ret = add_delayed_ref_head(trans, &head_ref->node, bytenr,
+ ret = add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
extent_op->is_data);
BUG_ON(ret);
+ if (waitqueue_active(&delayed_refs->seq_wait))
+ wake_up(&delayed_refs->seq_wait);
spin_unlock(&delayed_refs->lock);
return 0;
}
struct btrfs_delayed_ref_root *delayed_refs;
delayed_refs = &trans->transaction->delayed_refs;
- ref = find_ref_head(&delayed_refs->root, bytenr, NULL);
+ ref = find_ref_head(&delayed_refs->root, bytenr, NULL, 0);
if (ref)
return btrfs_delayed_node_to_head(ref);
return NULL;
/* the size of the extent */
u64 num_bytes;
+ /* seq number to keep track of insertion order */
+ u64 seq;
+
/* ref count on this data structure */
atomic_t refs;
struct btrfs_delayed_tree_ref {
struct btrfs_delayed_ref_node node;
- union {
- u64 root;
- u64 parent;
- };
+ u64 root;
+ u64 parent;
int level;
};
struct btrfs_delayed_data_ref {
struct btrfs_delayed_ref_node node;
- union {
- u64 root;
- u64 parent;
- };
+ u64 root;
+ u64 parent;
u64 objectid;
u64 offset;
};
int flushing;
u64 run_delayed_start;
+
+ /*
+ * seq number of delayed refs. We need to know if a backref was being
+ * added before the currently processed ref or afterwards.
+ */
+ u64 seq;
+
+ /*
+ * seq_list holds a list of all seq numbers that are currently being
+ * added to the list. While walking backrefs (btrfs_find_all_roots,
+ * qgroups), which might take some time, no newer ref must be processed,
+ * as it might influence the outcome of the walk.
+ */
+ struct list_head seq_head;
+
+ /*
+ * when the only refs we have in the list must not be processed, we want
+ * to wait for more refs to show up or for the end of backref walking.
+ */
+ wait_queue_head_t seq_wait;
};
static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
}
}
-int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
+int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
+ struct btrfs_trans_handle *trans,
u64 bytenr, u64 num_bytes, u64 parent,
u64 ref_root, int level, int action,
- struct btrfs_delayed_extent_op *extent_op);
-int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
+ struct btrfs_delayed_extent_op *extent_op,
+ int for_cow);
+int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
+ struct btrfs_trans_handle *trans,
u64 bytenr, u64 num_bytes,
u64 parent, u64 ref_root,
u64 owner, u64 offset, int action,
- struct btrfs_delayed_extent_op *extent_op);
-int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
+ struct btrfs_delayed_extent_op *extent_op,
+ int for_cow);
+int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
+ struct btrfs_trans_handle *trans,
u64 bytenr, u64 num_bytes,
struct btrfs_delayed_extent_op *extent_op);
struct btrfs_delayed_ref_head *head);
int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
struct list_head *cluster, u64 search_start);
+
+struct seq_list {
+ struct list_head list;
+ u64 seq;
+};
+
+static inline u64 inc_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs)
+{
+ assert_spin_locked(&delayed_refs->lock);
+ ++delayed_refs->seq;
+ return delayed_refs->seq;
+}
+
+static inline void
+btrfs_get_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs,
+ struct seq_list *elem)
+{
+ assert_spin_locked(&delayed_refs->lock);
+ elem->seq = delayed_refs->seq;
+ list_add_tail(&elem->list, &delayed_refs->seq_head);
+}
+
+static inline void
+btrfs_put_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs,
+ struct seq_list *elem)
+{
+ spin_lock(&delayed_refs->lock);
+ list_del(&elem->list);
+ wake_up(&delayed_refs->seq_wait);
+ spin_unlock(&delayed_refs->lock);
+}
+
+int btrfs_check_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs,
+ u64 seq);
+
+/*
+ * delayed refs with a ref_seq > 0 must be held back during backref walking.
+ * this only applies to items in one of the fs-trees. for_cow items never need
+ * to be held back, so they won't get a ref_seq number.
+ */
+static inline int need_ref_seq(int for_cow, u64 rootid)
+{
+ if (for_cow)
+ return 0;
+
+ if (rootid == BTRFS_FS_TREE_OBJECTID)
+ return 1;
+
+ if ((s64)rootid >= (s64)BTRFS_FIRST_FREE_OBJECTID)
+ return 1;
+
+ return 0;
+}
+
/*
* a node might live in a head or a regular ref, this lets you
* test for the proper type to use.
root->ref_cows = 0;
leaf = btrfs_alloc_free_block(trans, root, root->leafsize, 0,
- BTRFS_TREE_LOG_OBJECTID, NULL, 0, 0, 0);
+ BTRFS_TREE_LOG_OBJECTID, NULL,
+ 0, 0, 0, 0);
if (IS_ERR(leaf)) {
kfree(root);
return ERR_CAST(leaf);
int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
u64 bytenr, u64 num_bytes, u64 parent,
- u64 root_objectid, u64 owner, u64 offset)
+ u64 root_objectid, u64 owner, u64 offset, int for_cow)
{
int ret;
+ struct btrfs_fs_info *fs_info = root->fs_info;
+
BUG_ON(owner < BTRFS_FIRST_FREE_OBJECTID &&
root_objectid == BTRFS_TREE_LOG_OBJECTID);
if (owner < BTRFS_FIRST_FREE_OBJECTID) {
- ret = btrfs_add_delayed_tree_ref(trans, bytenr, num_bytes,
+ ret = btrfs_add_delayed_tree_ref(fs_info, trans, bytenr,
+ num_bytes,
parent, root_objectid, (int)owner,
- BTRFS_ADD_DELAYED_REF, NULL);
+ BTRFS_ADD_DELAYED_REF, NULL, for_cow);
} else {
- ret = btrfs_add_delayed_data_ref(trans, bytenr, num_bytes,
+ ret = btrfs_add_delayed_data_ref(fs_info, trans, bytenr,
+ num_bytes,
parent, root_objectid, owner, offset,
- BTRFS_ADD_DELAYED_REF, NULL);
+ BTRFS_ADD_DELAYED_REF, NULL, for_cow);
}
return ret;
}
}
}
+ /*
+ * locked_ref is the head node, so we have to go one
+ * node back for any delayed ref updates
+ */
+ ref = select_delayed_ref(locked_ref);
+
+ if (ref && ref->seq &&
+ btrfs_check_delayed_seq(delayed_refs, ref->seq)) {
+ /*
+ * there are still refs with lower seq numbers in the
+ * process of being added. Don't run this ref yet.
+ */
+ list_del_init(&locked_ref->cluster);
+ mutex_unlock(&locked_ref->mutex);
+ locked_ref = NULL;
+ delayed_refs->num_heads_ready++;
+ spin_unlock(&delayed_refs->lock);
+ cond_resched();
+ spin_lock(&delayed_refs->lock);
+ continue;
+ }
+
/*
* record the must insert reserved flag before we
* drop the spin lock.
extent_op = locked_ref->extent_op;
locked_ref->extent_op = NULL;
- /*
- * locked_ref is the head node, so we have to go one
- * node back for any delayed ref updates
- */
- ref = select_delayed_ref(locked_ref);
if (!ref) {
/* All delayed refs have been processed, Go ahead
* and send the head node to run_one_delayed_ref,
ref->in_tree = 0;
rb_erase(&ref->rb_node, &delayed_refs->root);
delayed_refs->num_entries--;
-
+ /*
+ * we modified num_entries, but as we're currently running
+ * delayed refs, skip
+ * wake_up(&delayed_refs->seq_wait);
+ * here.
+ */
spin_unlock(&delayed_refs->lock);
ret = run_one_delayed_ref(trans, root, ref, extent_op,
return count;
}
+
+static void wait_for_more_refs(struct btrfs_delayed_ref_root *delayed_refs,
+ unsigned long num_refs)
+{
+ struct list_head *first_seq = delayed_refs->seq_head.next;
+
+ spin_unlock(&delayed_refs->lock);
+ pr_debug("waiting for more refs (num %ld, first %p)\n",
+ num_refs, first_seq);
+ wait_event(delayed_refs->seq_wait,
+ num_refs != delayed_refs->num_entries ||
+ delayed_refs->seq_head.next != first_seq);
+ pr_debug("done waiting for more refs (num %ld, first %p)\n",
+ delayed_refs->num_entries, delayed_refs->seq_head.next);
+ spin_lock(&delayed_refs->lock);
+}
+
/*
* this starts processing the delayed reference count updates and
* extent insertions we have queued up so far. count can be
struct btrfs_delayed_ref_node *ref;
struct list_head cluster;
int ret;
+ u64 delayed_start;
int run_all = count == (unsigned long)-1;
int run_most = 0;
+ unsigned long num_refs = 0;
+ int consider_waiting;
if (root == root->fs_info->extent_root)
root = root->fs_info->tree_root;
delayed_refs = &trans->transaction->delayed_refs;
INIT_LIST_HEAD(&cluster);
again:
+ consider_waiting = 0;
spin_lock(&delayed_refs->lock);
if (count == 0) {
count = delayed_refs->num_entries * 2;
* of refs to process starting at the first one we are able to
* lock
*/
+ delayed_start = delayed_refs->run_delayed_start;
ret = btrfs_find_ref_cluster(trans, &cluster,
delayed_refs->run_delayed_start);
if (ret)
break;
+ if (delayed_start >= delayed_refs->run_delayed_start) {
+ if (consider_waiting == 0) {
+ /*
+ * btrfs_find_ref_cluster looped. let's do one
+ * more cycle. if we don't run any delayed ref
+ * during that cycle (because we can't because
+ * all of them are blocked) and if the number of
+ * refs doesn't change, we avoid busy waiting.
+ */
+ consider_waiting = 1;
+ num_refs = delayed_refs->num_entries;
+ } else {
+ wait_for_more_refs(delayed_refs, num_refs);
+ /*
+ * after waiting, things have changed. we
+ * dropped the lock and someone else might have
+ * run some refs, built new clusters and so on.
+ * therefore, we restart staleness detection.
+ */
+ consider_waiting = 0;
+ }
+ }
+
ret = run_clustered_refs(trans, root, &cluster);
BUG_ON(ret < 0);
if (count == 0)
break;
+
+ if (ret || delayed_refs->run_delayed_start == 0) {
+ /* refs were run, let's reset staleness detection */
+ consider_waiting = 0;
+ }
}
if (run_all) {
extent_op->update_key = 0;
extent_op->is_data = is_data ? 1 : 0;
- ret = btrfs_add_delayed_extent_op(trans, bytenr, num_bytes, extent_op);
+ ret = btrfs_add_delayed_extent_op(root->fs_info, trans, bytenr,
+ num_bytes, extent_op);
if (ret)
kfree(extent_op);
return ret;
static int __btrfs_mod_ref(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct extent_buffer *buf,
- int full_backref, int inc)
+ int full_backref, int inc, int for_cow)
{
u64 bytenr;
u64 num_bytes;
int level;
int ret = 0;
int (*process_func)(struct btrfs_trans_handle *, struct btrfs_root *,
- u64, u64, u64, u64, u64, u64);
+ u64, u64, u64, u64, u64, u64, int);
ref_root = btrfs_header_owner(buf);
nritems = btrfs_header_nritems(buf);
key.offset -= btrfs_file_extent_offset(buf, fi);
ret = process_func(trans, root, bytenr, num_bytes,
parent, ref_root, key.objectid,
- key.offset);
+ key.offset, for_cow);
if (ret)
goto fail;
} else {
bytenr = btrfs_node_blockptr(buf, i);
num_bytes = btrfs_level_size(root, level - 1);
ret = process_func(trans, root, bytenr, num_bytes,
- parent, ref_root, level - 1, 0);
+ parent, ref_root, level - 1, 0,
+ for_cow);
if (ret)
goto fail;
}
}
int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
- struct extent_buffer *buf, int full_backref)
+ struct extent_buffer *buf, int full_backref, int for_cow)
{
- return __btrfs_mod_ref(trans, root, buf, full_backref, 1);
+ return __btrfs_mod_ref(trans, root, buf, full_backref, 1, for_cow);
}
int btrfs_dec_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
- struct extent_buffer *buf, int full_backref)
+ struct extent_buffer *buf, int full_backref, int for_cow)
{
- return __btrfs_mod_ref(trans, root, buf, full_backref, 0);
+ return __btrfs_mod_ref(trans, root, buf, full_backref, 0, for_cow);
}
static int write_one_cache_group(struct btrfs_trans_handle *trans,
rb_erase(&head->node.rb_node, &delayed_refs->root);
delayed_refs->num_entries--;
+ if (waitqueue_active(&delayed_refs->seq_wait))
+ wake_up(&delayed_refs->seq_wait);
/*
* we don't take a ref on the node because we're removing it from the
void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct extent_buffer *buf,
- u64 parent, int last_ref)
+ u64 parent, int last_ref, int for_cow)
{
struct btrfs_block_group_cache *cache = NULL;
int ret;
if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID) {
- ret = btrfs_add_delayed_tree_ref(trans, buf->start, buf->len,
- parent, root->root_key.objectid,
- btrfs_header_level(buf),
- BTRFS_DROP_DELAYED_REF, NULL);
+ ret = btrfs_add_delayed_tree_ref(root->fs_info, trans,
+ buf->start, buf->len,
+ parent, root->root_key.objectid,
+ btrfs_header_level(buf),
+ BTRFS_DROP_DELAYED_REF, NULL, for_cow);
BUG_ON(ret);
}
btrfs_put_block_group(cache);
}
-int btrfs_free_extent(struct btrfs_trans_handle *trans,
- struct btrfs_root *root,
- u64 bytenr, u64 num_bytes, u64 parent,
- u64 root_objectid, u64 owner, u64 offset)
+int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+ u64 bytenr, u64 num_bytes, u64 parent, u64 root_objectid,
+ u64 owner, u64 offset, int for_cow)
{
int ret;
+ struct btrfs_fs_info *fs_info = root->fs_info;
/*
* tree log blocks never actually go into the extent allocation
btrfs_pin_extent(root, bytenr, num_bytes, 1);
ret = 0;
} else if (owner < BTRFS_FIRST_FREE_OBJECTID) {
- ret = btrfs_add_delayed_tree_ref(trans, bytenr, num_bytes,
+ ret = btrfs_add_delayed_tree_ref(fs_info, trans, bytenr,
+ num_bytes,
parent, root_objectid, (int)owner,
- BTRFS_DROP_DELAYED_REF, NULL);
+ BTRFS_DROP_DELAYED_REF, NULL, for_cow);
BUG_ON(ret);
} else {
- ret = btrfs_add_delayed_data_ref(trans, bytenr, num_bytes,
- parent, root_objectid, owner,
- offset, BTRFS_DROP_DELAYED_REF, NULL);
+ ret = btrfs_add_delayed_data_ref(fs_info, trans, bytenr,
+ num_bytes,
+ parent, root_objectid, owner,
+ offset, BTRFS_DROP_DELAYED_REF,
+ NULL, for_cow);
BUG_ON(ret);
}
return ret;
BUG_ON(root_objectid == BTRFS_TREE_LOG_OBJECTID);
- ret = btrfs_add_delayed_data_ref(trans, ins->objectid, ins->offset,
- 0, root_objectid, owner, offset,
- BTRFS_ADD_DELAYED_EXTENT, NULL);
+ ret = btrfs_add_delayed_data_ref(root->fs_info, trans, ins->objectid,
+ ins->offset, 0,
+ root_objectid, owner, offset,
+ BTRFS_ADD_DELAYED_EXTENT, NULL, 0);
return ret;
}
struct btrfs_root *root, u32 blocksize,
u64 parent, u64 root_objectid,
struct btrfs_disk_key *key, int level,
- u64 hint, u64 empty_size)
+ u64 hint, u64 empty_size, int for_cow)
{
struct btrfs_key ins;
struct btrfs_block_rsv *block_rsv;
extent_op->update_flags = 1;
extent_op->is_data = 0;
- ret = btrfs_add_delayed_tree_ref(trans, ins.objectid,
+ ret = btrfs_add_delayed_tree_ref(root->fs_info, trans,
+ ins.objectid,
ins.offset, parent, root_objectid,
level, BTRFS_ADD_DELAYED_EXTENT,
- extent_op);
+ extent_op, for_cow);
BUG_ON(ret);
}
return buf;
int keep_locks;
int reada_slot;
int reada_count;
+ int for_reloc;
};
#define DROP_REFERENCE 1
/* wc->stage == UPDATE_BACKREF */
if (!(wc->flags[level] & flag)) {
BUG_ON(!path->locks[level]);
- ret = btrfs_inc_ref(trans, root, eb, 1);
+ ret = btrfs_inc_ref(trans, root, eb, 1, wc->for_reloc);
BUG_ON(ret);
- ret = btrfs_dec_ref(trans, root, eb, 0);
+ ret = btrfs_dec_ref(trans, root, eb, 0, wc->for_reloc);
BUG_ON(ret);
ret = btrfs_set_disk_extent_flags(trans, root, eb->start,
eb->len, flag, 0);
}
ret = btrfs_free_extent(trans, root, bytenr, blocksize, parent,
- root->root_key.objectid, level - 1, 0);
+ root->root_key.objectid, level - 1, 0, 0);
BUG_ON(ret);
}
btrfs_tree_unlock(next);
if (wc->refs[level] == 1) {
if (level == 0) {
if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF)
- ret = btrfs_dec_ref(trans, root, eb, 1);
+ ret = btrfs_dec_ref(trans, root, eb, 1,
+ wc->for_reloc);
else
- ret = btrfs_dec_ref(trans, root, eb, 0);
+ ret = btrfs_dec_ref(trans, root, eb, 0,
+ wc->for_reloc);
BUG_ON(ret);
}
/* make block locked assertion in clean_tree_block happy */
btrfs_header_owner(path->nodes[level + 1]));
}
- btrfs_free_tree_block(trans, root, eb, parent, wc->refs[level] == 1);
+ btrfs_free_tree_block(trans, root, eb, parent, wc->refs[level] == 1, 0);
out:
wc->refs[level] = 0;
wc->flags[level] = 0;
* blocks are properly updated.
*/
void btrfs_drop_snapshot(struct btrfs_root *root,
- struct btrfs_block_rsv *block_rsv, int update_ref)
+ struct btrfs_block_rsv *block_rsv, int update_ref,
+ int for_reloc)
{
struct btrfs_path *path;
struct btrfs_trans_handle *trans;
wc->stage = DROP_REFERENCE;
wc->update_ref = update_ref;
wc->keep_locks = 0;
+ wc->for_reloc = for_reloc;
wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(root);
while (1) {
* drop subtree rooted at tree block 'node'.
*
* NOTE: this function will unlock and release tree block 'node'
+ * only used by relocation code
*/
int btrfs_drop_subtree(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
wc->stage = DROP_REFERENCE;
wc->update_ref = 0;
wc->keep_locks = 1;
+ wc->for_reloc = 1;
wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(root);
while (1) {
atomic_set(&eb->blocking_writers, 0);
atomic_set(&eb->spinning_readers, 0);
atomic_set(&eb->spinning_writers, 0);
+ eb->lock_nested = 0;
init_waitqueue_head(&eb->write_lock_wq);
init_waitqueue_head(&eb->read_lock_wq);
struct list_head leak_list;
struct rcu_head rcu_head;
atomic_t refs;
+ pid_t lock_owner;
/* count of read lock holders on the extent buffer */
atomic_t write_locks;
atomic_t blocking_readers;
atomic_t spinning_readers;
atomic_t spinning_writers;
+ int lock_nested;
/* protects write locks */
rwlock_t lock;
disk_bytenr, num_bytes, 0,
root->root_key.objectid,
new_key.objectid,
- start - extent_offset);
+ start - extent_offset, 0);
BUG_ON(ret);
*hint_byte = disk_bytenr;
}
disk_bytenr, num_bytes, 0,
root->root_key.objectid,
key.objectid, key.offset -
- extent_offset);
+ extent_offset, 0);
BUG_ON(ret);
inode_sub_bytes(inode,
extent_end - key.offset);
ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
root->root_key.objectid,
- ino, orig_offset);
+ ino, orig_offset, 0);
BUG_ON(ret);
if (split == start) {
del_nr++;
ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
0, root->root_key.objectid,
- ino, orig_offset);
+ ino, orig_offset, 0);
BUG_ON(ret);
}
other_start = 0;
del_nr++;
ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
0, root->root_key.objectid,
- ino, orig_offset);
+ ino, orig_offset, 0);
BUG_ON(ret);
}
if (del_nr == 0) {
ret = btrfs_free_extent(trans, root, extent_start,
extent_num_bytes, 0,
btrfs_header_owner(leaf),
- ino, extent_offset);
+ ino, extent_offset, 0);
BUG_ON(ret);
}
}
flush_dcache_page(page);
} else if (create && PageUptodate(page)) {
- WARN_ON(1);
+ BUG();
if (!trans) {
kunmap(page);
free_extent_map(em);
return PTR_ERR(trans);
leaf = btrfs_alloc_free_block(trans, root, root->leafsize,
- 0, objectid, NULL, 0, 0, 0);
+ 0, objectid, NULL, 0, 0, 0, 0);
if (IS_ERR(leaf)) {
ret = PTR_ERR(leaf);
goto fail;
disko, diskl, 0,
root->root_key.objectid,
btrfs_ino(inode),
- new_key.offset - datao);
+ new_key.offset - datao,
+ 0);
BUG_ON(ret);
}
} else if (type == BTRFS_FILE_EXTENT_INLINE) {
{
int ret = 0;
int size;
- u64 extent_offset;
+ u64 extent_item_pos;
struct btrfs_ioctl_logical_ino_args *loi;
struct btrfs_data_container *inodes = NULL;
struct btrfs_path *path = NULL;
}
ret = extent_from_logical(root->fs_info, loi->logical, path, &key);
+ btrfs_release_path(path);
if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK)
ret = -ENOENT;
if (ret < 0)
goto out;
- extent_offset = loi->logical - key.objectid;
+ extent_item_pos = loi->logical - key.objectid;
ret = iterate_extent_inodes(root->fs_info, path, key.objectid,
- extent_offset, build_ino_list, inodes);
+ extent_item_pos, build_ino_list,
+ inodes);
if (ret < 0)
goto out;
*/
void btrfs_set_lock_blocking_rw(struct extent_buffer *eb, int rw)
{
+ if (eb->lock_nested) {
+ read_lock(&eb->lock);
+ if (eb->lock_nested && current->pid == eb->lock_owner) {
+ read_unlock(&eb->lock);
+ return;
+ }
+ read_unlock(&eb->lock);
+ }
if (rw == BTRFS_WRITE_LOCK) {
if (atomic_read(&eb->blocking_writers) == 0) {
WARN_ON(atomic_read(&eb->spinning_writers) != 1);
*/
void btrfs_clear_lock_blocking_rw(struct extent_buffer *eb, int rw)
{
+ if (eb->lock_nested) {
+ read_lock(&eb->lock);
+ if (&eb->lock_nested && current->pid == eb->lock_owner) {
+ read_unlock(&eb->lock);
+ return;
+ }
+ read_unlock(&eb->lock);
+ }
if (rw == BTRFS_WRITE_LOCK_BLOCKING) {
BUG_ON(atomic_read(&eb->blocking_writers) != 1);
write_lock(&eb->lock);
void btrfs_tree_read_lock(struct extent_buffer *eb)
{
again:
+ read_lock(&eb->lock);
+ if (atomic_read(&eb->blocking_writers) &&
+ current->pid == eb->lock_owner) {
+ /*
+ * This extent is already write-locked by our thread. We allow
+ * an additional read lock to be added because it's for the same
+ * thread. btrfs_find_all_roots() depends on this as it may be
+ * called on a partly (write-)locked tree.
+ */
+ BUG_ON(eb->lock_nested);
+ eb->lock_nested = 1;
+ read_unlock(&eb->lock);
+ return;
+ }
+ read_unlock(&eb->lock);
wait_event(eb->write_lock_wq, atomic_read(&eb->blocking_writers) == 0);
read_lock(&eb->lock);
if (atomic_read(&eb->blocking_writers)) {
read_unlock(&eb->lock);
- wait_event(eb->write_lock_wq,
- atomic_read(&eb->blocking_writers) == 0);
goto again;
}
atomic_inc(&eb->read_locks);
}
atomic_inc(&eb->write_locks);
atomic_inc(&eb->spinning_writers);
+ eb->lock_owner = current->pid;
return 1;
}
*/
void btrfs_tree_read_unlock(struct extent_buffer *eb)
{
+ if (eb->lock_nested) {
+ read_lock(&eb->lock);
+ if (eb->lock_nested && current->pid == eb->lock_owner) {
+ eb->lock_nested = 0;
+ read_unlock(&eb->lock);
+ return;
+ }
+ read_unlock(&eb->lock);
+ }
btrfs_assert_tree_read_locked(eb);
WARN_ON(atomic_read(&eb->spinning_readers) == 0);
atomic_dec(&eb->spinning_readers);
*/
void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb)
{
+ if (eb->lock_nested) {
+ read_lock(&eb->lock);
+ if (eb->lock_nested && current->pid == eb->lock_owner) {
+ eb->lock_nested = 0;
+ read_unlock(&eb->lock);
+ return;
+ }
+ read_unlock(&eb->lock);
+ }
btrfs_assert_tree_read_locked(eb);
WARN_ON(atomic_read(&eb->blocking_readers) == 0);
if (atomic_dec_and_test(&eb->blocking_readers))
WARN_ON(atomic_read(&eb->spinning_writers));
atomic_inc(&eb->spinning_writers);
atomic_inc(&eb->write_locks);
+ eb->lock_owner = current->pid;
return 0;
}
ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
num_bytes, parent,
btrfs_header_owner(leaf),
- key.objectid, key.offset);
+ key.objectid, key.offset, 1);
BUG_ON(ret);
ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
parent, btrfs_header_owner(leaf),
- key.objectid, key.offset);
+ key.objectid, key.offset, 1);
BUG_ON(ret);
}
if (dirty)
ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
path->nodes[level]->start,
- src->root_key.objectid, level - 1, 0);
+ src->root_key.objectid, level - 1, 0,
+ 1);
BUG_ON(ret);
ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
0, dest->root_key.objectid, level - 1,
- 0);
+ 0, 1);
BUG_ON(ret);
ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
path->nodes[level]->start,
- src->root_key.objectid, level - 1, 0);
+ src->root_key.objectid, level - 1, 0,
+ 1);
BUG_ON(ret);
ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
0, dest->root_key.objectid, level - 1,
- 0);
+ 0, 1);
BUG_ON(ret);
btrfs_unlock_up_safe(path, 0);
} else {
list_del_init(&reloc_root->root_list);
}
- btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0);
+ btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
}
if (found) {
node->eb->start, blocksize,
upper->eb->start,
btrfs_header_owner(upper->eb),
- node->level, 0);
+ node->level, 0, 1);
BUG_ON(ret);
ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
u8 ref_level;
unsigned long ptr = 0;
const int bufsize = 4096;
- u64 extent_offset;
+ u64 extent_item_pos;
path = btrfs_alloc_path();
if (ret < 0)
goto out;
- extent_offset = swarn.logical - found_key.objectid;
+ extent_item_pos = swarn.logical - found_key.objectid;
swarn.extent_item_size = found_key.offset;
eb = path->nodes[0];
ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
item_size = btrfs_item_size_nr(eb, path->slots[0]);
+ btrfs_release_path(path);
if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
do {
} else {
swarn.path = path;
iterate_extent_inodes(fs_info, path, found_key.objectid,
- extent_offset,
+ extent_item_pos,
scrub_print_warning_inode, &swarn);
}
WARN_ON(atomic_read(&transaction->use_count) == 0);
if (atomic_dec_and_test(&transaction->use_count)) {
BUG_ON(!list_empty(&transaction->list));
+ WARN_ON(transaction->delayed_refs.root.rb_node);
+ WARN_ON(!list_empty(&transaction->delayed_refs.seq_head));
memset(transaction, 0, sizeof(*transaction));
kmem_cache_free(btrfs_transaction_cachep, transaction);
}
cur_trans->delayed_refs.num_heads = 0;
cur_trans->delayed_refs.flushing = 0;
cur_trans->delayed_refs.run_delayed_start = 0;
+ cur_trans->delayed_refs.seq = 1;
+ init_waitqueue_head(&cur_trans->delayed_refs.seq_wait);
spin_lock_init(&cur_trans->commit_lock);
spin_lock_init(&cur_trans->delayed_refs.lock);
+ INIT_LIST_HEAD(&cur_trans->delayed_refs.seq_head);
INIT_LIST_HEAD(&cur_trans->pending_snapshots);
list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
if (btrfs_header_backref_rev(root->node) <
BTRFS_MIXED_BACKREF_REV)
- btrfs_drop_snapshot(root, NULL, 0);
+ btrfs_drop_snapshot(root, NULL, 0, 0);
else
- btrfs_drop_snapshot(root, NULL, 1);
+ btrfs_drop_snapshot(root, NULL, 1, 0);
}
return 0;
}
ret = btrfs_inc_extent_ref(trans, root,
ins.objectid, ins.offset,
0, root->root_key.objectid,
- key->objectid, offset);
+ key->objectid, offset, 0);
BUG_ON(ret);
} else {
/*
--- /dev/null
+/*
+ * Copyright (C) 2011 STRATO AG
+ * written by Arne Jansen <sensille@gmx.net>
+ * Distributed under the GNU GPL license version 2.
+ */
+
+#include <linux/slab.h>
+#include <linux/module.h>
+#include "ulist.h"
+
+/*
+ * ulist is a generic data structure to hold a collection of unique u64
+ * values. The only operations it supports is adding to the list and
+ * enumerating it.
+ * It is possible to store an auxiliary value along with the key.
+ *
+ * The implementation is preliminary and can probably be sped up
+ * significantly. A first step would be to store the values in an rbtree
+ * as soon as ULIST_SIZE is exceeded.
+ *
+ * A sample usage for ulists is the enumeration of directed graphs without
+ * visiting a node twice. The pseudo-code could look like this:
+ *
+ * ulist = ulist_alloc();
+ * ulist_add(ulist, root);
+ * elem = NULL;
+ *
+ * while ((elem = ulist_next(ulist, elem)) {
+ * for (all child nodes n in elem)
+ * ulist_add(ulist, n);
+ * do something useful with the node;
+ * }
+ * ulist_free(ulist);
+ *
+ * This assumes the graph nodes are adressable by u64. This stems from the
+ * usage for tree enumeration in btrfs, where the logical addresses are
+ * 64 bit.
+ *
+ * It is also useful for tree enumeration which could be done elegantly
+ * recursively, but is not possible due to kernel stack limitations. The
+ * loop would be similar to the above.
+ */
+
+/**
+ * ulist_init - freshly initialize a ulist
+ * @ulist: the ulist to initialize
+ *
+ * Note: don't use this function to init an already used ulist, use
+ * ulist_reinit instead.
+ */
+void ulist_init(struct ulist *ulist)
+{
+ ulist->nnodes = 0;
+ ulist->nodes = ulist->int_nodes;
+ ulist->nodes_alloced = ULIST_SIZE;
+}
+EXPORT_SYMBOL(ulist_init);
+
+/**
+ * ulist_fini - free up additionally allocated memory for the ulist
+ * @ulist: the ulist from which to free the additional memory
+ *
+ * This is useful in cases where the base 'struct ulist' has been statically
+ * allocated.
+ */
+void ulist_fini(struct ulist *ulist)
+{
+ /*
+ * The first ULIST_SIZE elements are stored inline in struct ulist.
+ * Only if more elements are alocated they need to be freed.
+ */
+ if (ulist->nodes_alloced > ULIST_SIZE)
+ kfree(ulist->nodes);
+ ulist->nodes_alloced = 0; /* in case ulist_fini is called twice */
+}
+EXPORT_SYMBOL(ulist_fini);
+
+/**
+ * ulist_reinit - prepare a ulist for reuse
+ * @ulist: ulist to be reused
+ *
+ * Free up all additional memory allocated for the list elements and reinit
+ * the ulist.
+ */
+void ulist_reinit(struct ulist *ulist)
+{
+ ulist_fini(ulist);
+ ulist_init(ulist);
+}
+EXPORT_SYMBOL(ulist_reinit);
+
+/**
+ * ulist_alloc - dynamically allocate a ulist
+ * @gfp_mask: allocation flags to for base allocation
+ *
+ * The allocated ulist will be returned in an initialized state.
+ */
+struct ulist *ulist_alloc(unsigned long gfp_mask)
+{
+ struct ulist *ulist = kmalloc(sizeof(*ulist), gfp_mask);
+
+ if (!ulist)
+ return NULL;
+
+ ulist_init(ulist);
+
+ return ulist;
+}
+EXPORT_SYMBOL(ulist_alloc);
+
+/**
+ * ulist_free - free dynamically allocated ulist
+ * @ulist: ulist to free
+ *
+ * It is not necessary to call ulist_fini before.
+ */
+void ulist_free(struct ulist *ulist)
+{
+ if (!ulist)
+ return;
+ ulist_fini(ulist);
+ kfree(ulist);
+}
+EXPORT_SYMBOL(ulist_free);
+
+/**
+ * ulist_add - add an element to the ulist
+ * @ulist: ulist to add the element to
+ * @val: value to add to ulist
+ * @aux: auxiliary value to store along with val
+ * @gfp_mask: flags to use for allocation
+ *
+ * Note: locking must be provided by the caller. In case of rwlocks write
+ * locking is needed
+ *
+ * Add an element to a ulist. The @val will only be added if it doesn't
+ * already exist. If it is added, the auxiliary value @aux is stored along with
+ * it. In case @val already exists in the ulist, @aux is ignored, even if
+ * it differs from the already stored value.
+ *
+ * ulist_add returns 0 if @val already exists in ulist and 1 if @val has been
+ * inserted.
+ * In case of allocation failure -ENOMEM is returned and the ulist stays
+ * unaltered.
+ */
+int ulist_add(struct ulist *ulist, u64 val, unsigned long aux,
+ unsigned long gfp_mask)
+{
+ int i;
+
+ for (i = 0; i < ulist->nnodes; ++i) {
+ if (ulist->nodes[i].val == val)
+ return 0;
+ }
+
+ if (ulist->nnodes >= ulist->nodes_alloced) {
+ u64 new_alloced = ulist->nodes_alloced + 128;
+ struct ulist_node *new_nodes;
+ void *old = NULL;
+
+ /*
+ * if nodes_alloced == ULIST_SIZE no memory has been allocated
+ * yet, so pass NULL to krealloc
+ */
+ if (ulist->nodes_alloced > ULIST_SIZE)
+ old = ulist->nodes;
+
+ new_nodes = krealloc(old, sizeof(*new_nodes) * new_alloced,
+ gfp_mask);
+ if (!new_nodes)
+ return -ENOMEM;
+
+ if (!old)
+ memcpy(new_nodes, ulist->int_nodes,
+ sizeof(ulist->int_nodes));
+
+ ulist->nodes = new_nodes;
+ ulist->nodes_alloced = new_alloced;
+ }
+ ulist->nodes[ulist->nnodes].val = val;
+ ulist->nodes[ulist->nnodes].aux = aux;
+ ++ulist->nnodes;
+
+ return 1;
+}
+EXPORT_SYMBOL(ulist_add);
+
+/**
+ * ulist_next - iterate ulist
+ * @ulist: ulist to iterate
+ * @prev: previously returned element or %NULL to start iteration
+ *
+ * Note: locking must be provided by the caller. In case of rwlocks only read
+ * locking is needed
+ *
+ * This function is used to iterate an ulist. The iteration is started with
+ * @prev = %NULL. It returns the next element from the ulist or %NULL when the
+ * end is reached. No guarantee is made with respect to the order in which
+ * the elements are returned. They might neither be returned in order of
+ * addition nor in ascending order.
+ * It is allowed to call ulist_add during an enumeration. Newly added items
+ * are guaranteed to show up in the running enumeration.
+ */
+struct ulist_node *ulist_next(struct ulist *ulist, struct ulist_node *prev)
+{
+ int next;
+
+ if (ulist->nnodes == 0)
+ return NULL;
+
+ if (!prev)
+ return &ulist->nodes[0];
+
+ next = (prev - ulist->nodes) + 1;
+ if (next < 0 || next >= ulist->nnodes)
+ return NULL;
+
+ return &ulist->nodes[next];
+}
+EXPORT_SYMBOL(ulist_next);
--- /dev/null
+/*
+ * Copyright (C) 2011 STRATO AG
+ * written by Arne Jansen <sensille@gmx.net>
+ * Distributed under the GNU GPL license version 2.
+ *
+ */
+
+#ifndef __ULIST__
+#define __ULIST__
+
+/*
+ * ulist is a generic data structure to hold a collection of unique u64
+ * values. The only operations it supports is adding to the list and
+ * enumerating it.
+ * It is possible to store an auxiliary value along with the key.
+ *
+ * The implementation is preliminary and can probably be sped up
+ * significantly. A first step would be to store the values in an rbtree
+ * as soon as ULIST_SIZE is exceeded.
+ */
+
+/*
+ * number of elements statically allocated inside struct ulist
+ */
+#define ULIST_SIZE 16
+
+/*
+ * element of the list
+ */
+struct ulist_node {
+ u64 val; /* value to store */
+ unsigned long aux; /* auxiliary value saved along with the val */
+};
+
+struct ulist {
+ /*
+ * number of elements stored in list
+ */
+ unsigned long nnodes;
+
+ /*
+ * number of nodes we already have room for
+ */
+ unsigned long nodes_alloced;
+
+ /*
+ * pointer to the array storing the elements. The first ULIST_SIZE
+ * elements are stored inline. In this case the it points to int_nodes.
+ * After exceeding ULIST_SIZE, dynamic memory is allocated.
+ */
+ struct ulist_node *nodes;
+
+ /*
+ * inline storage space for the first ULIST_SIZE entries
+ */
+ struct ulist_node int_nodes[ULIST_SIZE];
+};
+
+void ulist_init(struct ulist *ulist);
+void ulist_fini(struct ulist *ulist);
+void ulist_reinit(struct ulist *ulist);
+struct ulist *ulist_alloc(unsigned long gfp_mask);
+void ulist_free(struct ulist *ulist);
+int ulist_add(struct ulist *ulist, u64 val, unsigned long aux,
+ unsigned long gfp_mask);
+struct ulist_node *ulist_next(struct ulist *ulist, struct ulist_node *prev);
+
+#endif
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