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 {