1 files changed, 316 insertions, 369 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index fedf8b9f03a2..2b960278a2f9 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -197,14 +197,7 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
         u32 nritems;
         int ret = 0;
         int level;
-        struct btrfs_root *new_root;
-
-        new_root = kmalloc(sizeof(*new_root), GFP_NOFS);
-        if (!new_root)
-                return -ENOMEM;
-
-        memcpy(new_root, root, sizeof(*new_root));
-        new_root->root_key.objectid = new_root_objectid;
+        struct btrfs_disk_key disk_key;
 
         WARN_ON(root->ref_cows && trans->transid !=
                 root->fs_info->running_transaction->transid);
@@ -212,28 +205,37 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
 
         level = btrfs_header_level(buf);
         nritems = btrfs_header_nritems(buf);
+        if (level == 0)
+                btrfs_item_key(buf, &disk_key, 0);
+        else
+                btrfs_node_key(buf, &disk_key, 0);
 
-        cow = btrfs_alloc_free_block(trans, new_root, buf->len, 0,
-                                     new_root_objectid, trans->transid,
-                                     level, buf->start, 0);
-        if (IS_ERR(cow)) {
-                kfree(new_root);
+        cow = btrfs_alloc_free_block(trans, root, buf->len, 0,
+                                     new_root_objectid, &disk_key, level,
+                                     buf->start, 0);
+        if (IS_ERR(cow))
                 return PTR_ERR(cow);
-        }
 
         copy_extent_buffer(cow, buf, 0, 0, cow->len);
         btrfs_set_header_bytenr(cow, cow->start);
         btrfs_set_header_generation(cow, trans->transid);
-        btrfs_set_header_owner(cow, new_root_objectid);
-        btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN);
+        btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
+        btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
+                                     BTRFS_HEADER_FLAG_RELOC);
+        if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
+                btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
+        else
+                btrfs_set_header_owner(cow, new_root_objectid);
 
         write_extent_buffer(cow, root->fs_info->fsid,
                             (unsigned long)btrfs_header_fsid(cow),
                             BTRFS_FSID_SIZE);
 
         WARN_ON(btrfs_header_generation(buf) > trans->transid);
-        ret = btrfs_inc_ref(trans, new_root, buf, cow, NULL);
-        kfree(new_root);
+        if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
+                ret = btrfs_inc_ref(trans, root, cow, 1);
+        else
+                ret = btrfs_inc_ref(trans, root, cow, 0);
 
         if (ret)
                 return ret;
@@ -244,6 +246,125 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
 }
 
 /*
+ * check if the tree block can be shared by multiple trees
+ */
+int btrfs_block_can_be_shared(struct btrfs_root *root,
+                              struct extent_buffer *buf)
+{
+        /*
+         * Tree blocks not in refernece counted trees and tree roots
+         * are never shared. If a block was allocated after the last
+         * snapshot and the block was not allocated by tree relocation,
+         * we know the block is not shared.
+         */
+        if (root->ref_cows &&
+            buf != root->node && buf != root->commit_root &&
+            (btrfs_header_generation(buf) <=
+             btrfs_root_last_snapshot(&root->root_item) ||
+             btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
+                return 1;
+#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
+        if (root->ref_cows &&
+            btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
+                return 1;
+#endif
+        return 0;
+}
+
+static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
+                                       struct btrfs_root *root,
+                                       struct extent_buffer *buf,
+                                       struct extent_buffer *cow)
+{
+        u64 refs;
+        u64 owner;
+        u64 flags;
+        u64 new_flags = 0;
+        int ret;
+
+        /*
+         * Backrefs update rules:
+         *
+         * Always use full backrefs for extent pointers in tree block
+         * allocated by tree relocation.
+         *
+         * If a shared tree block is no longer referenced by its owner
+         * tree (btrfs_header_owner(buf) == root->root_key.objectid),
+         * use full backrefs for extent pointers in tree block.
+         *
+         * If a tree block is been relocating
+         * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
+         * use full backrefs for extent pointers in tree block.
+         * The reason for this is some operations (such as drop tree)
+         * are only allowed for blocks use full backrefs.
+         */
+
+        if (btrfs_block_can_be_shared(root, buf)) {
+                ret = btrfs_lookup_extent_info(trans, root, buf->start,
+                                               buf->len, &refs, &flags);
+                BUG_ON(ret);
+                BUG_ON(refs == 0);
+        } else {
+                refs = 1;
+                if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
+                    btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
+                        flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
+                else
+                        flags = 0;
+        }
+
+        owner = btrfs_header_owner(buf);
+        BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
+               !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
+
+        if (refs > 1) {
+                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);
+                        BUG_ON(ret);
+
+                        if (root->root_key.objectid ==
+                            BTRFS_TREE_RELOC_OBJECTID) {
+                                ret = btrfs_dec_ref(trans, root, buf, 0);
+                                BUG_ON(ret);
+                                ret = btrfs_inc_ref(trans, root, cow, 1);
+                                BUG_ON(ret);
+                        }
+                        new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
+                } else {
+
+                        if (root->root_key.objectid ==
+                            BTRFS_TREE_RELOC_OBJECTID)
+                                ret = btrfs_inc_ref(trans, root, cow, 1);
+                        else
+                                ret = btrfs_inc_ref(trans, root, cow, 0);
+                        BUG_ON(ret);
+                }
+                if (new_flags != 0) {
+                        ret = btrfs_set_disk_extent_flags(trans, root,
+                                                          buf->start,
+                                                          buf->len,
+                                                          new_flags, 0);
+                        BUG_ON(ret);
+                }
+        } else {
+                if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
+                        if (root->root_key.objectid ==
+                            BTRFS_TREE_RELOC_OBJECTID)
+                                ret = btrfs_inc_ref(trans, root, cow, 1);
+                        else
+                                ret = btrfs_inc_ref(trans, root, cow, 0);
+                        BUG_ON(ret);
+                        ret = btrfs_dec_ref(trans, root, buf, 1);
+                        BUG_ON(ret);
+                }
+                clean_tree_block(trans, root, buf);
+        }
+        return 0;
+}
+
+/*
  * does the dirty work in cow of a single block.  The parent block (if
  * supplied) is updated to point to the new cow copy.  The new buffer is marked
  * dirty and returned locked.  If you modify the block it needs to be marked
@@ -262,34 +383,39 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
                              struct extent_buffer **cow_ret,
                              u64 search_start, u64 empty_size)
 {
-        u64 parent_start;
+        struct btrfs_disk_key disk_key;
         struct extent_buffer *cow;
-        u32 nritems;
-        int ret = 0;
         int level;
         int unlock_orig = 0;
+        u64 parent_start;
 
         if (*cow_ret == buf)
                 unlock_orig = 1;
 
         btrfs_assert_tree_locked(buf);
 
-        if (parent)
-                parent_start = parent->start;
-        else
-                parent_start = 0;
-
         WARN_ON(root->ref_cows && trans->transid !=
                 root->fs_info->running_transaction->transid);
         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
 
         level = btrfs_header_level(buf);
-        nritems = btrfs_header_nritems(buf);
 
-        cow = btrfs_alloc_free_block(trans, root, buf->len,
-                                     parent_start, root->root_key.objectid,
-                                     trans->transid, level,
-                                     search_start, empty_size);
+        if (level == 0)
+                btrfs_item_key(buf, &disk_key, 0);
+        else
+                btrfs_node_key(buf, &disk_key, 0);
+
+        if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
+                if (parent)
+                        parent_start = parent->start;
+                else
+                        parent_start = 0;
+        } else
+                parent_start = 0;
+
+        cow = btrfs_alloc_free_block(trans, root, buf->len, parent_start,
+                                     root->root_key.objectid, &disk_key,
+                                     level, search_start, empty_size);
         if (IS_ERR(cow))
                 return PTR_ERR(cow);
 
@@ -298,83 +424,53 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
         copy_extent_buffer(cow, buf, 0, 0, cow->len);
         btrfs_set_header_bytenr(cow, cow->start);
         btrfs_set_header_generation(cow, trans->transid);
-        btrfs_set_header_owner(cow, root->root_key.objectid);
-        btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN);
+        btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
+        btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
+                                     BTRFS_HEADER_FLAG_RELOC);
+        if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
+                btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
+        else
+                btrfs_set_header_owner(cow, root->root_key.objectid);
 
         write_extent_buffer(cow, root->fs_info->fsid,
                             (unsigned long)btrfs_header_fsid(cow),
                             BTRFS_FSID_SIZE);
 
-        WARN_ON(btrfs_header_generation(buf) > trans->transid);
-        if (btrfs_header_generation(buf) != trans->transid) {
-                u32 nr_extents;
-                ret = btrfs_inc_ref(trans, root, buf, cow, &nr_extents);
-                if (ret)
-                        return ret;
-
-                ret = btrfs_cache_ref(trans, root, buf, nr_extents);
-                WARN_ON(ret);
-        } else if (btrfs_header_owner(buf) == BTRFS_TREE_RELOC_OBJECTID) {
-                /*
-                 * There are only two places that can drop reference to
-                 * tree blocks owned by living reloc trees, one is here,
-                 * the other place is btrfs_drop_subtree. In both places,
-                 * we check reference count while tree block is locked.
-                 * Furthermore, if reference count is one, it won't get
-                 * increased by someone else.
-                 */
-                u32 refs;
-                ret = btrfs_lookup_extent_ref(trans, root, buf->start,
-                                              buf->len, &refs);
-                BUG_ON(ret);
-                if (refs == 1) {
-                        ret = btrfs_update_ref(trans, root, buf, cow,
-                                               0, nritems);
-                        clean_tree_block(trans, root, buf);
-                } else {
-                        ret = btrfs_inc_ref(trans, root, buf, cow, NULL);
-                }
-                BUG_ON(ret);
-        } else {
-                ret = btrfs_update_ref(trans, root, buf, cow, 0, nritems);
-                if (ret)
-                        return ret;
-                clean_tree_block(trans, root, buf);
-        }
-
-        if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
-                ret = btrfs_reloc_tree_cache_ref(trans, root, cow, buf->start);
-                WARN_ON(ret);
-        }
+        update_ref_for_cow(trans, root, buf, cow);
 
         if (buf == root->node) {
                 WARN_ON(parent && parent != buf);
+                if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
+                    btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
+                        parent_start = buf->start;
+                else
+                        parent_start = 0;
 
                 spin_lock(&root->node_lock);
                 root->node = cow;
                 extent_buffer_get(cow);
                 spin_unlock(&root->node_lock);
 
-                if (buf != root->commit_root) {
-                        btrfs_free_extent(trans, root, buf->start,
-                                          buf->len, buf->start,
-                                          root->root_key.objectid,
-                                          btrfs_header_generation(buf),
-                                          level, 1);
-                }
+                btrfs_free_extent(trans, root, buf->start, buf->len,
+                                  parent_start, root->root_key.objectid,
+                                  level, 0);
                 free_extent_buffer(buf);
                 add_root_to_dirty_list(root);
         } else {
+                if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
+                        parent_start = parent->start;
+                else
+                        parent_start = 0;
+
+                WARN_ON(trans->transid != btrfs_header_generation(parent));
                 btrfs_set_node_blockptr(parent, parent_slot,
                                         cow->start);
-                WARN_ON(trans->transid == 0);
                 btrfs_set_node_ptr_generation(parent, parent_slot,
                                               trans->transid);
                 btrfs_mark_buffer_dirty(parent);
-                WARN_ON(btrfs_header_generation(parent) != trans->transid);
                 btrfs_free_extent(trans, root, buf->start, buf->len,
-                                  parent_start, btrfs_header_owner(parent),
-                                  btrfs_header_generation(parent), level, 1);
+                                  parent_start, root->root_key.objectid,
+                                  level, 0);
         }
         if (unlock_orig)
                 btrfs_tree_unlock(buf);
@@ -384,6 +480,18 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
         return 0;
 }
 
+static inline int should_cow_block(struct btrfs_trans_handle *trans,
+                                   struct btrfs_root *root,
+                                   struct extent_buffer *buf)
+{
+        if (btrfs_header_generation(buf) == trans->transid &&
+            !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
+            !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
+              btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
+                return 0;
+        return 1;
+}
+
 /*
  * cows a single block, see __btrfs_cow_block for the real work.
  * This version of it has extra checks so that a block isn't cow'd more than
@@ -411,9 +519,7 @@ noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
                 WARN_ON(1);
         }
 
-        if (btrfs_header_generation(buf) == trans->transid &&
-            btrfs_header_owner(buf) == root->root_key.objectid &&
-            !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) {
+        if (!should_cow_block(trans, root, buf)) {
                 *cow_ret = buf;
                 return 0;
         }
@@ -469,7 +575,7 @@ static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
 /*
  * same as comp_keys only with two btrfs_key's
  */
-static int comp_cpu_keys(struct btrfs_key *k1, struct btrfs_key *k2)
+int btrfs_comp_cpu_keys(struct btrfs_key *k1, struct btrfs_key *k2)
 {
         if (k1->objectid > k2->objectid)
                 return 1;
@@ -845,6 +951,12 @@ static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
         return -1;
 }
 
+int btrfs_bin_search(struct extent_buffer *eb, struct btrfs_key *key,
+                     int level, int *slot)
+{
+        return bin_search(eb, key, level, slot);
+}
+
 /* given a node and slot number, this reads the blocks it points to.  The
  * extent buffer is returned with a reference taken (but unlocked).
  * NULL is returned on error.
@@ -921,13 +1033,6 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
                 root->node = child;
                 spin_unlock(&root->node_lock);
 
-                ret = btrfs_update_extent_ref(trans, root, child->start,
-                                              child->len,
-                                              mid->start, child->start,
-                                              root->root_key.objectid,
-                                              trans->transid, level - 1);
-                BUG_ON(ret);
-
                 add_root_to_dirty_list(root);
                 btrfs_tree_unlock(child);
 
@@ -938,9 +1043,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
                 /* once for the path */
                 free_extent_buffer(mid);
                 ret = btrfs_free_extent(trans, root, mid->start, mid->len,
-                                        mid->start, root->root_key.objectid,
-                                        btrfs_header_generation(mid),
-                                        level, 1);
+                                        0, root->root_key.objectid, level, 1);
                 /* once for the root ptr */
                 free_extent_buffer(mid);
                 return ret;
@@ -998,7 +1101,6 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
                         ret = wret;
                 if (btrfs_header_nritems(right) == 0) {
                         u64 bytenr = right->start;
-                        u64 generation = btrfs_header_generation(parent);
                         u32 blocksize = right->len;
 
                         clean_tree_block(trans, root, right);
@@ -1010,9 +1112,9 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
                         if (wret)
                                 ret = wret;
                         wret = btrfs_free_extent(trans, root, bytenr,
-                                                 blocksize, parent->start,
-                                                 btrfs_header_owner(parent),
-                                                 generation, level, 1);
+                                                 blocksize, 0,
+                                                 root->root_key.objectid,
+                                                 level, 0);
                         if (wret)
                                 ret = wret;
                 } else {
@@ -1047,7 +1149,6 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
         }
         if (btrfs_header_nritems(mid) == 0) {
                 /* we've managed to empty the middle node, drop it */
-                u64 root_gen = btrfs_header_generation(parent);
                 u64 bytenr = mid->start;
                 u32 blocksize = mid->len;
 
@@ -1059,9 +1160,8 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
                 if (wret)
                         ret = wret;
                 wret = btrfs_free_extent(trans, root, bytenr, blocksize,
-                                         parent->start,
-                                         btrfs_header_owner(parent),
-                                         root_gen, level, 1);
+                                         0, root->root_key.objectid,
+                                         level, 0);
                 if (wret)
                         ret = wret;
         } else {
@@ -1437,7 +1537,7 @@ noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
 {
         int i;
 
-        if (path->keep_locks || path->lowest_level)
+        if (path->keep_locks)
                 return;
 
         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
@@ -1614,10 +1714,17 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
                 lowest_unlock = 2;
 
 again:
-        if (p->skip_locking)
-                b = btrfs_root_node(root);
-        else
-                b = btrfs_lock_root_node(root);
+        if (p->search_commit_root) {
+                b = root->commit_root;
+                extent_buffer_get(b);
+                if (!p->skip_locking)
+                        btrfs_tree_lock(b);
+        } else {
+                if (p->skip_locking)
+                        b = btrfs_root_node(root);
+                else
+                        b = btrfs_lock_root_node(root);
+        }
 
         while (b) {
                 level = btrfs_header_level(b);
@@ -1638,11 +1745,9 @@ again:
                          * then we don't want to set the path blocking,
                          * so we test it here
                          */
-                        if (btrfs_header_generation(b) == trans->transid &&
-                            btrfs_header_owner(b) == root->root_key.objectid &&
-                            !btrfs_header_flag(b, BTRFS_HEADER_FLAG_WRITTEN)) {
+                        if (!should_cow_block(trans, root, b))
                                 goto cow_done;
-                        }
+
                         btrfs_set_path_blocking(p);
 
                         wret = btrfs_cow_block(trans, root, b,
@@ -1764,138 +1869,6 @@ done:
         return ret;
 }
 
-int btrfs_merge_path(struct btrfs_trans_handle *trans,
-                     struct btrfs_root *root,
-                     struct btrfs_key *node_keys,
-                     u64 *nodes, int lowest_level)
-{
-        struct extent_buffer *eb;
-        struct extent_buffer *parent;
-        struct btrfs_key key;
-        u64 bytenr;
-        u64 generation;
-        u32 blocksize;
-        int level;
-        int slot;
-        int key_match;
-        int ret;
-
-        eb = btrfs_lock_root_node(root);
-        ret = btrfs_cow_block(trans, root, eb, NULL, 0, &eb);
-        BUG_ON(ret);
-
-        btrfs_set_lock_blocking(eb);
-
-        parent = eb;
-        while (1) {
-                level = btrfs_header_level(parent);
-                if (level == 0 || level <= lowest_level)
-                        break;
-
-                ret = bin_search(parent, &node_keys[lowest_level], level,
-                                 &slot);
-                if (ret && slot > 0)
-                        slot--;
-
-                bytenr = btrfs_node_blockptr(parent, slot);
-                if (nodes[level - 1] == bytenr)
-                        break;
-
-                blocksize = btrfs_level_size(root, level - 1);
-                generation = btrfs_node_ptr_generation(parent, slot);
-                btrfs_node_key_to_cpu(eb, &key, slot);
-                key_match = !memcmp(&key, &node_keys[level - 1], sizeof(key));
-
-                if (generation == trans->transid) {
-                        eb = read_tree_block(root, bytenr, blocksize,
-                                             generation);
-                        btrfs_tree_lock(eb);
-                        btrfs_set_lock_blocking(eb);
-                }
-
-                /*
-                 * if node keys match and node pointer hasn't been modified
-                 * in the running transaction, we can merge the path. for
-                 * blocks owened by reloc trees, the node pointer check is
-                 * skipped, this is because these blocks are fully controlled
-                 * by the space balance code, no one else can modify them.
-                 */
-                if (!nodes[level - 1] || !key_match ||
-                    (generation == trans->transid &&
-                     btrfs_header_owner(eb) != BTRFS_TREE_RELOC_OBJECTID)) {
-                        if (level == 1 || level == lowest_level + 1) {
-                                if (generation == trans->transid) {
-                                        btrfs_tree_unlock(eb);
-                                        free_extent_buffer(eb);
-                                }
-                                break;
-                        }
-
-                        if (generation != trans->transid) {
-                                eb = read_tree_block(root, bytenr, blocksize,
-                                                generation);
-                                btrfs_tree_lock(eb);
-                                btrfs_set_lock_blocking(eb);
-                        }
-
-                        ret = btrfs_cow_block(trans, root, eb, parent, slot,
-                                              &eb);
-                        BUG_ON(ret);
-
-                        if (root->root_key.objectid ==
-                            BTRFS_TREE_RELOC_OBJECTID) {
-                                if (!nodes[level - 1]) {
-                                        nodes[level - 1] = eb->start;
-                                        memcpy(&node_keys[level - 1], &key,
-                                               sizeof(node_keys[0]));
-                                } else {
-                                        WARN_ON(1);
-                                }
-                        }
-
-                        btrfs_tree_unlock(parent);
-                        free_extent_buffer(parent);
-                        parent = eb;
-                        continue;
-                }
-
-                btrfs_set_node_blockptr(parent, slot, nodes[level - 1]);
-                btrfs_set_node_ptr_generation(parent, slot, trans->transid);
-                btrfs_mark_buffer_dirty(parent);
-
-                ret = btrfs_inc_extent_ref(trans, root,
-                                        nodes[level - 1],
-                                        blocksize, parent->start,
-                                        btrfs_header_owner(parent),
-                                        btrfs_header_generation(parent),
-                                        level - 1);
-                BUG_ON(ret);
-
-                /*
-                 * If the block was created in the running transaction,
-                 * it's possible this is the last reference to it, so we
-                 * should drop the subtree.
-                 */
-                if (generation == trans->transid) {
-                        ret = btrfs_drop_subtree(trans, root, eb, parent);
-                        BUG_ON(ret);
-                        btrfs_tree_unlock(eb);
-                        free_extent_buffer(eb);
-                } else {
-                        ret = btrfs_free_extent(trans, root, bytenr,
-                                        blocksize, parent->start,
-                                        btrfs_header_owner(parent),
-                                        btrfs_header_generation(parent),
-                                        level - 1, 1);
-                        BUG_ON(ret);
-                }
-                break;
-        }
-        btrfs_tree_unlock(parent);
-        free_extent_buffer(parent);
-        return 0;
-}
-
 /*
  * adjust the pointers going up the tree, starting at level
  * making sure the right key of each node is points to 'key'.
@@ -2021,9 +1994,6 @@ static int push_node_left(struct btrfs_trans_handle *trans,
         btrfs_mark_buffer_dirty(src);
         btrfs_mark_buffer_dirty(dst);
 
-        ret = btrfs_update_ref(trans, root, src, dst, dst_nritems, push_items);
-        BUG_ON(ret);
-
         return ret;
 }
 
@@ -2083,9 +2053,6 @@ static int balance_node_right(struct btrfs_trans_handle *trans,
         btrfs_mark_buffer_dirty(src);
         btrfs_mark_buffer_dirty(dst);
 
-        ret = btrfs_update_ref(trans, root, src, dst, 0, push_items);
-        BUG_ON(ret);
-
         return ret;
 }
 
@@ -2105,7 +2072,6 @@ static noinline int insert_new_root(struct btrfs_trans_handle *trans,
         struct extent_buffer *c;
         struct extent_buffer *old;
         struct btrfs_disk_key lower_key;
-        int ret;
 
         BUG_ON(path->nodes[level]);
         BUG_ON(path->nodes[level-1] != root->node);
@@ -2117,16 +2083,17 @@ static noinline int insert_new_root(struct btrfs_trans_handle *trans,
                 btrfs_node_key(lower, &lower_key, 0);
 
         c = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
-                                   root->root_key.objectid, trans->transid,
+                                   root->root_key.objectid, &lower_key,
                                    level, root->node->start, 0);
         if (IS_ERR(c))
                 return PTR_ERR(c);
 
-        memset_extent_buffer(c, 0, 0, root->nodesize);
+        memset_extent_buffer(c, 0, 0, sizeof(struct btrfs_header));
         btrfs_set_header_nritems(c, 1);
         btrfs_set_header_level(c, level);
         btrfs_set_header_bytenr(c, c->start);
         btrfs_set_header_generation(c, trans->transid);
+        btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV);
         btrfs_set_header_owner(c, root->root_key.objectid);
 
         write_extent_buffer(c, root->fs_info->fsid,
@@ -2151,12 +2118,6 @@ static noinline int insert_new_root(struct btrfs_trans_handle *trans,
         root->node = c;
         spin_unlock(&root->node_lock);
 
-        ret = btrfs_update_extent_ref(trans, root, lower->start,
-                                      lower->len, lower->start, c->start,
-                                      root->root_key.objectid,
-                                      trans->transid, level - 1);
-        BUG_ON(ret);
-
         /* the super has an extra ref to root->node */
         free_extent_buffer(old);
 
@@ -2244,20 +2205,21 @@ static noinline int split_node(struct btrfs_trans_handle *trans,
         }
 
         c_nritems = btrfs_header_nritems(c);
+        mid = (c_nritems + 1) / 2;
+        btrfs_node_key(c, &disk_key, mid);
 
-        split = btrfs_alloc_free_block(trans, root, root->nodesize,
-                                        path->nodes[level + 1]->start,
+        split = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
                                         root->root_key.objectid,
-                                        trans->transid, level, c->start, 0);
+                                        &disk_key, level, c->start, 0);
         if (IS_ERR(split))
                 return PTR_ERR(split);
 
-        btrfs_set_header_flags(split, btrfs_header_flags(c));
+        memset_extent_buffer(split, 0, 0, sizeof(struct btrfs_header));
         btrfs_set_header_level(split, btrfs_header_level(c));
         btrfs_set_header_bytenr(split, split->start);
         btrfs_set_header_generation(split, trans->transid);
+        btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV);
         btrfs_set_header_owner(split, root->root_key.objectid);
-        btrfs_set_header_flags(split, 0);
         write_extent_buffer(split, root->fs_info->fsid,
                             (unsigned long)btrfs_header_fsid(split),
                             BTRFS_FSID_SIZE);
@@ -2265,7 +2227,6 @@ static noinline int split_node(struct btrfs_trans_handle *trans,
                             (unsigned long)btrfs_header_chunk_tree_uuid(split),
                             BTRFS_UUID_SIZE);
 
-        mid = (c_nritems + 1) / 2;
 
         copy_extent_buffer(split, c,
                            btrfs_node_key_ptr_offset(0),
@@ -2278,16 +2239,12 @@ static noinline int split_node(struct btrfs_trans_handle *trans,
         btrfs_mark_buffer_dirty(c);
         btrfs_mark_buffer_dirty(split);
 
-        btrfs_node_key(split, &disk_key, 0);
         wret = insert_ptr(trans, root, path, &disk_key, split->start,
                           path->slots[level + 1] + 1,
                           level + 1);
         if (wret)
                 ret = wret;
 
-        ret = btrfs_update_ref(trans, root, c, split, 0, c_nritems - mid);
-        BUG_ON(ret);
-
         if (path->slots[level] >= mid) {
                 path->slots[level] -= mid;
                 btrfs_tree_unlock(c);
@@ -2360,7 +2317,6 @@ static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
         u32 right_nritems;
         u32 data_end;
         u32 this_item_size;
-        int ret;
 
         if (empty)
                 nr = 0;
@@ -2473,9 +2429,6 @@ static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
                 btrfs_mark_buffer_dirty(left);
         btrfs_mark_buffer_dirty(right);
 
-        ret = btrfs_update_ref(trans, root, left, right, 0, push_items);
-        BUG_ON(ret);
-
         btrfs_item_key(right, &disk_key, 0);
         btrfs_set_node_key(upper, &disk_key, slot + 1);
         btrfs_mark_buffer_dirty(upper);
@@ -2720,10 +2673,6 @@ static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
         if (right_nritems)
                 btrfs_mark_buffer_dirty(right);
 
-        ret = btrfs_update_ref(trans, root, right, left,
-                               old_left_nritems, push_items);
-        BUG_ON(ret);
-
         btrfs_item_key(right, &disk_key, 0);
         wret = fixup_low_keys(trans, root, path, &disk_key, 1);
         if (wret)
@@ -2880,9 +2829,6 @@ static noinline int copy_for_split(struct btrfs_trans_handle *trans,
         btrfs_mark_buffer_dirty(l);
         BUG_ON(path->slots[0] != slot);
 
-        ret = btrfs_update_ref(trans, root, l, right, 0, nritems);
-        BUG_ON(ret);
-
         if (mid <= slot) {
                 btrfs_tree_unlock(path->nodes[0]);
                 free_extent_buffer(path->nodes[0]);
@@ -2911,6 +2857,7 @@ static noinline int split_leaf(struct btrfs_trans_handle *trans,
                                struct btrfs_path *path, int data_size,
                                int extend)
 {
+        struct btrfs_disk_key disk_key;
         struct extent_buffer *l;
         u32 nritems;
         int mid;
@@ -2918,7 +2865,7 @@ static noinline int split_leaf(struct btrfs_trans_handle *trans,
         struct extent_buffer *right;
         int ret = 0;
         int wret;
-        int double_split;
+        int split;
         int num_doubles = 0;
 
         /* first try to make some room by pushing left and right */
@@ -2945,16 +2892,53 @@ static noinline int split_leaf(struct btrfs_trans_handle *trans,
                         return ret;
         }
 again:
-        double_split = 0;
+        split = 1;
         l = path->nodes[0];
         slot = path->slots[0];
         nritems = btrfs_header_nritems(l);
         mid = (nritems + 1) / 2;
 
-        right = btrfs_alloc_free_block(trans, root, root->leafsize,
-                                        path->nodes[1]->start,
+        if (mid <= slot) {
+                if (nritems == 1 ||
+                    leaf_space_used(l, mid, nritems - mid) + data_size >
+                        BTRFS_LEAF_DATA_SIZE(root)) {
+                        if (slot >= nritems) {
+                                split = 0;
+                        } else {
+                                mid = slot;
+                                if (mid != nritems &&
+                                    leaf_space_used(l, mid, nritems - mid) +
+                                    data_size > BTRFS_LEAF_DATA_SIZE(root)) {
+                                        split = 2;
+                                }
+                        }
+                }
+        } else {
+                if (leaf_space_used(l, 0, mid) + data_size >
+                        BTRFS_LEAF_DATA_SIZE(root)) {
+                        if (!extend && data_size && slot == 0) {
+                                split = 0;
+                        } else if ((extend || !data_size) && slot == 0) {
+                                mid = 1;
+                        } else {
+                                mid = slot;
+                                if (mid != nritems &&
+                                    leaf_space_used(l, mid, nritems - mid) +
+                                    data_size > BTRFS_LEAF_DATA_SIZE(root)) {
+                                        split = 2 ;
+                                }
+                        }
+                }
+        }
+
+        if (split == 0)
+                btrfs_cpu_key_to_disk(&disk_key, ins_key);
+        else
+                btrfs_item_key(l, &disk_key, mid);
+
+        right = btrfs_alloc_free_block(trans, root, root->leafsize, 0,
                                         root->root_key.objectid,
-                                        trans->transid, 0, l->start, 0);
+                                        &disk_key, 0, l->start, 0);
         if (IS_ERR(right)) {
                 BUG_ON(1);
                 return PTR_ERR(right);
@@ -2963,6 +2947,7 @@ again:
         memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
         btrfs_set_header_bytenr(right, right->start);
         btrfs_set_header_generation(right, trans->transid);
+        btrfs_set_header_backref_rev(right, BTRFS_MIXED_BACKREF_REV);
         btrfs_set_header_owner(right, root->root_key.objectid);
         btrfs_set_header_level(right, 0);
         write_extent_buffer(right, root->fs_info->fsid,
@@ -2973,79 +2958,47 @@ again:
                             (unsigned long)btrfs_header_chunk_tree_uuid(right),
                             BTRFS_UUID_SIZE);
 
-        if (mid <= slot) {
-                if (nritems == 1 ||
-                    leaf_space_used(l, mid, nritems - mid) + data_size >
-                        BTRFS_LEAF_DATA_SIZE(root)) {
-                        if (slot >= nritems) {
-                                struct btrfs_disk_key disk_key;
-
-                                btrfs_cpu_key_to_disk(&disk_key, ins_key);
-                                btrfs_set_header_nritems(right, 0);
-                                wret = insert_ptr(trans, root, path,
-                                                  &disk_key, right->start,
-                                                  path->slots[1] + 1, 1);
-                                if (wret)
-                                        ret = wret;
+        if (split == 0) {
+                if (mid <= slot) {
+                        btrfs_set_header_nritems(right, 0);
+                        wret = insert_ptr(trans, root, path,
+                                          &disk_key, right->start,
+                                          path->slots[1] + 1, 1);
+                        if (wret)
+                                ret = wret;
 
-                                btrfs_tree_unlock(path->nodes[0]);
-                                free_extent_buffer(path->nodes[0]);
-                                path->nodes[0] = right;
-                                path->slots[0] = 0;
-                                path->slots[1] += 1;
-                                btrfs_mark_buffer_dirty(right);
-                                return ret;
-                        }
-                        mid = slot;
-                        if (mid != nritems &&
-                            leaf_space_used(l, mid, nritems - mid) +
-                            data_size > BTRFS_LEAF_DATA_SIZE(root)) {
-                                double_split = 1;
-                        }
-                }
-        } else {
-                if (leaf_space_used(l, 0, mid) + data_size >
-                        BTRFS_LEAF_DATA_SIZE(root)) {
-                        if (!extend && data_size && slot == 0) {
-                                struct btrfs_disk_key disk_key;
-
-                                btrfs_cpu_key_to_disk(&disk_key, ins_key);
-                                btrfs_set_header_nritems(right, 0);
-                                wret = insert_ptr(trans, root, path,
-                                                  &disk_key,
-                                                  right->start,
-                                                  path->slots[1], 1);
+                        btrfs_tree_unlock(path->nodes[0]);
+                        free_extent_buffer(path->nodes[0]);
+                        path->nodes[0] = right;
+                        path->slots[0] = 0;
+                        path->slots[1] += 1;
+                } else {
+                        btrfs_set_header_nritems(right, 0);
+                        wret = insert_ptr(trans, root, path,
+                                          &disk_key,
+                                          right->start,
+                                          path->slots[1], 1);
+                        if (wret)
+                                ret = wret;
+                        btrfs_tree_unlock(path->nodes[0]);
+                        free_extent_buffer(path->nodes[0]);
+                        path->nodes[0] = right;
+                        path->slots[0] = 0;
+                        if (path->slots[1] == 0) {
+                                wret = fixup_low_keys(trans, root,
+                                                path, &disk_key, 1);
                                 if (wret)
                                         ret = wret;
-                                btrfs_tree_unlock(path->nodes[0]);
-                                free_extent_buffer(path->nodes[0]);
-                                path->nodes[0] = right;
-                                path->slots[0] = 0;
-                                if (path->slots[1] == 0) {
-                                        wret = fixup_low_keys(trans, root,
-                                                      path, &disk_key, 1);
-                                        if (wret)
-                                                ret = wret;
-                                }
-                                btrfs_mark_buffer_dirty(right);
-                                return ret;
-                        } else if ((extend || !data_size) && slot == 0) {
-                                mid = 1;
-                        } else {
-                                mid = slot;
-                                if (mid != nritems &&
-                                    leaf_space_used(l, mid, nritems - mid) +
-                                    data_size > BTRFS_LEAF_DATA_SIZE(root)) {
-                                        double_split = 1;
-                                }
                         }
                 }
+                btrfs_mark_buffer_dirty(right);
+                return ret;
         }
 
         ret = copy_for_split(trans, root, path, l, right, slot, mid, nritems);
         BUG_ON(ret);
 
-        if (double_split) {
+        if (split == 2) {
                 BUG_ON(num_doubles != 0);
                 num_doubles++;
                 goto again;
@@ -3447,7 +3400,7 @@ int btrfs_insert_some_items(struct btrfs_trans_handle *trans,
                 /* figure out how many keys we can insert in here */
                 total_data = data_size[0];
                 for (i = 1; i < nr; i++) {
-                        if (comp_cpu_keys(&found_key, cpu_key + i) <= 0)
+                        if (btrfs_comp_cpu_keys(&found_key, cpu_key + i) <= 0)
                                 break;
                         total_data += data_size[i];
                 }
@@ -3745,9 +3698,7 @@ static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 
 /*
  * a helper function to delete the leaf pointed to by path->slots[1] and
- * path->nodes[1].  bytenr is the node block pointer, but since the callers
- * already know it, it is faster to have them pass it down than to
- * read it out of the node again.
+ * path->nodes[1].
  *
  * This deletes the pointer in path->nodes[1] and frees the leaf
  * block extent.  zero is returned if it all worked out, < 0 otherwise.
@@ -3755,15 +3706,14 @@ static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  * The path must have already been setup for deleting the leaf, including
  * all the proper balancing.  path->nodes[1] must be locked.
  */
-noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
-                            struct btrfs_root *root,
-                            struct btrfs_path *path, u64 bytenr)
+static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
+                                   struct btrfs_root *root,
+                                   struct btrfs_path *path,
+                                   struct extent_buffer *leaf)
 {
         int ret;
-        u64 root_gen = btrfs_header_generation(path->nodes[1]);
-        u64 parent_start = path->nodes[1]->start;
-        u64 parent_owner = btrfs_header_owner(path->nodes[1]);
 
+        WARN_ON(btrfs_header_generation(leaf) != trans->transid);
         ret = del_ptr(trans, root, path, 1, path->slots[1]);
         if (ret)
                 return ret;
@@ -3774,10 +3724,8 @@ noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
          */
         btrfs_unlock_up_safe(path, 0);
 
-        ret = btrfs_free_extent(trans, root, bytenr,
-                                btrfs_level_size(root, 0),
-                                parent_start, parent_owner,
-                                root_gen, 0, 1);
+        ret = btrfs_free_extent(trans, root, leaf->start, leaf->len,
+                                0, root->root_key.objectid, 0, 0);
         return ret;
 }
 /*
@@ -3845,7 +3793,7 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                 if (leaf == root->node) {
                         btrfs_set_header_level(leaf, 0);
                 } else {
-                        ret = btrfs_del_leaf(trans, root, path, leaf->start);
+                        ret = btrfs_del_leaf(trans, root, path, leaf);
                         BUG_ON(ret);
                 }
         } else {
@@ -3884,8 +3832,7 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 
                         if (btrfs_header_nritems(leaf) == 0) {
                                 path->slots[1] = slot;
-                                ret = btrfs_del_leaf(trans, root, path,
-                                                     leaf->start);
+                                ret = btrfs_del_leaf(trans, root, path, leaf);
                                 BUG_ON(ret);
                                 free_extent_buffer(leaf);
                         } else {