Btrfs: fix tree mod logging

While running the test btrfs/004 from xfstests in a loop, it failed
about 1 time out of 20 runs in my desktop. The failure happened in
the backref walking part of the test, and the test's error message was
like this:

btrfs/004 93s ... [failed, exit status 1] - output mismatch (see /home/fdmanana/git/hub/xfstests_2/results//btrfs/004.out.bad)
--- tests/btrfs/004.out 2013-11-26 18:25:29.263333714 +0000
+++ /home/fdmanana/git/hub/xfstests_2/results//btrfs/004.out.bad 2013-12-10 15:25:10.327518516 +0000
@@ -1,3 +1,8 @@
QA output created by 004
*** test backref walking
-*** done
+unexpected output from
+ /home/fdmanana/git/hub/btrfs-progs/btrfs inspect-internal logical-resolve -P 141512704 /home/fdmanana/btrfs-tests/scratch_1
+expected inum: 405, expected address: 454656, file: /home/fdmanana/btrfs-tests/scratch_1/snap1/p0/d6/d3d/d156/fce, got:
+
...
(Run 'diff -u tests/btrfs/004.out /home/fdmanana/git/hub/xfstests_2/results//btrfs/004.out.bad' to see the entire diff)
Ran: btrfs/004
Failures: btrfs/004
Failed 1 of 1 tests

But immediately after the test finished, the btrfs inspect-internal command
returned the expected output:

$ btrfs inspect-internal logical-resolve -P 141512704 /home/fdmanana/btrfs-tests/scratch_1
inode 405 offset 454656 root 258
inode 405 offset 454656 root 5

It turned out this was because the btrfs_search_old_slot() calls performed
during backref walking (backref.c:__resolve_indirect_ref) were not finding
anything. The reason for this turned out to be that the tree mod logging
code was not logging some node multi-step operations atomically, therefore
btrfs_search_old_slot() callers iterated often over an incomplete tree that
wasn't fully consistent with any tree state from the past. Besides missing
items, this often (but not always) resulted in -EIO errors during old slot
searches, reported in dmesg like this:

[ 4299.933936] ------------[ cut here ]------------
[ 4299.933949] WARNING: CPU: 0 PID: 23190 at fs/btrfs/ctree.c:1343 btrfs_search_old_slot+0x57b/0xab0 [btrfs]()
[ 4299.933950] Modules linked in: btrfs raid6_pq xor pci_stub vboxpci(O) vboxnetadp(O) vboxnetflt(O) vboxdrv(O) bnep rfcomm bluetooth parport_pc ppdev binfmt_misc joydev snd_hda_codec_h
[ 4299.933977] CPU: 0 PID: 23190 Comm: btrfs Tainted: G W O 3.12.0-fdm-btrfs-next-16+ #70
[ 4299.933978] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./Z77 Pro4, BIOS P1.50 09/04/2012
[ 4299.933979] 000000000000053f ffff8806f3fd98f8 ffffffff8176d284 0000000000000007
[ 4299.933982] 0000000000000000 ffff8806f3fd9938 ffffffff8104a81c ffff880659c64b70
[ 4299.933984] ffff880659c643d0 ffff8806599233d8 ffff880701e2e938 0000160000000000
[ 4299.933987] Call Trace:
[ 4299.933991] [<ffffffff8176d284>] dump_stack+0x55/0x76
[ 4299.933994] [<ffffffff8104a81c>] warn_slowpath_common+0x8c/0xc0
[ 4299.933997] [<ffffffff8104a86a>] warn_slowpath_null+0x1a/0x20
[ 4299.934003] [<ffffffffa065d3bb>] btrfs_search_old_slot+0x57b/0xab0 [btrfs]
[ 4299.934005] [<ffffffff81775f3b>] ? _raw_read_unlock+0x2b/0x50
[ 4299.934010] [<ffffffffa0655001>] ? __tree_mod_log_search+0x81/0xc0 [btrfs]
[ 4299.934019] [<ffffffffa06dd9b0>] __resolve_indirect_refs+0x130/0x5f0 [btrfs]
[ 4299.934027] [<ffffffffa06a21f1>] ? free_extent_buffer+0x61/0xc0 [btrfs]
[ 4299.934034] [<ffffffffa06de39c>] find_parent_nodes+0x1fc/0xe40 [btrfs]
[ 4299.934042] [<ffffffffa06b13e0>] ? defrag_lookup_extent+0xe0/0xe0 [btrfs]
[ 4299.934048] [<ffffffffa06b13e0>] ? defrag_lookup_extent+0xe0/0xe0 [btrfs]
[ 4299.934056] [<ffffffffa06df980>] iterate_extent_inodes+0xe0/0x250 [btrfs]
[ 4299.934058] [<ffffffff817762db>] ? _raw_spin_unlock+0x2b/0x50
[ 4299.934065] [<ffffffffa06dfb82>] iterate_inodes_from_logical+0x92/0xb0 [btrfs]
[ 4299.934071] [<ffffffffa06b13e0>] ? defrag_lookup_extent+0xe0/0xe0 [btrfs]
[ 4299.934078] [<ffffffffa06b7015>] btrfs_ioctl+0xf65/0x1f60 [btrfs]
[ 4299.934080] [<ffffffff811658b8>] ? handle_mm_fault+0x278/0xb00
[ 4299.934083] [<ffffffff81075563>] ? up_read+0x23/0x40
[ 4299.934085] [<ffffffff8177a41c>] ? __do_page_fault+0x20c/0x5a0
[ 4299.934088] [<ffffffff811b2946>] do_vfs_ioctl+0x96/0x570
[ 4299.934090] [<ffffffff81776e23>] ? error_sti+0x5/0x6
[ 4299.934093] [<ffffffff810b71e8>] ? trace_hardirqs_off_caller+0x28/0xd0
[ 4299.934096] [<ffffffff81776a09>] ? retint_swapgs+0xe/0x13
[ 4299.934098] [<ffffffff811b2eb1>] SyS_ioctl+0x91/0xb0
[ 4299.934100] [<ffffffff813eecde>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[ 4299.934102] [<ffffffff8177ef12>] system_call_fastpath+0x16/0x1b
[ 4299.934102] [<ffffffff8177ef12>] system_call_fastpath+0x16/0x1b
[ 4299.934104] ---[ end trace 48f0cfc902491414 ]---
[ 4299.934378] btrfs bad fsid on block 0

These tree mod log operations that must be performed atomically, tree_mod_log_free_eb,
tree_mod_log_eb_copy, tree_mod_log_insert_root and tree_mod_log_insert_move, used to
be performed atomically before the following commit:

c8cc6341653721b54760480b0d0d9b5f09b46741
(Btrfs: stop using GFP_ATOMIC for the tree mod log allocations)

That change removed the atomicity of such operations. This patch restores the
atomicity while still not doing the GFP_ATOMIC allocations of tree_mod_elem
structures, so it has to do the allocations using GFP_NOFS before acquiring
the mod log lock.

This issue has been experienced by several users recently, such as for example:

http://www.spinics.net/lists/linux-btrfs/msg28574.html

After running the btrfs/004 test for 679 consecutive iterations with this
patch applied, I didn't ran into the issue anymore.

Cc: [e-mail]
Signed-off-by: Filipe David Borba Manana <[e-mail]>
Signed-off-by: Josef Bacik <[e-mail]>
Signed-off-by: Chris Mason <[e-mail]>

fs/btrfs/ctree.c

···
 			      struct extent_buffer *src_buf);
 static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
 		    int level, int slot);
-static void tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
+static int tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
 				 struct extent_buffer *eb);
 
 struct btrfs_path *btrfs_alloc_path(void)
···
  * the index is the shifted logical of the *new* root node for root replace
  * operations, or the shifted logical of the affected block for all other
  * operations.
+ *
+ * Note: must be called with write lock (tree_mod_log_write_lock).
  */
 static noinline int
 __tree_mod_log_insert(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm)
···
 	struct rb_node **new;
 	struct rb_node *parent = NULL;
 	struct tree_mod_elem *cur;
-	int ret = 0;
 
 	BUG_ON(!tm);
-
-	tree_mod_log_write_lock(fs_info);
-	if (list_empty(&fs_info->tree_mod_seq_list)) {
-		tree_mod_log_write_unlock(fs_info);
-		/*
-		 * Ok we no longer care about logging modifications, free up tm
-		 * and return 0.  Any callers shouldn't be using tm after
-		 * calling tree_mod_log_insert, but if they do we can just
-		 * change this to return a special error code to let the callers
-		 * do their own thing.
-		 */
-		kfree(tm);
-		return 0;
-	}
 
 	spin_lock(&fs_info->tree_mod_seq_lock);
 	tm->seq = btrfs_inc_tree_mod_seq_minor(fs_info);
···
 			new = &((*new)->rb_left);
 		else if (cur->seq > tm->seq)
 			new = &((*new)->rb_right);
-		else {
-			ret = -EEXIST;
-			kfree(tm);
-			goto out;
-		}
+		else
+			return -EEXIST;
 	}
 
 	rb_link_node(&tm->node, parent, new);
 	rb_insert_color(&tm->node, tm_root);
-out:
-	tree_mod_log_write_unlock(fs_info);
-	return ret;
+	return 0;
 }
 
 /*
···
 		return 1;
 	if (eb && btrfs_header_level(eb) == 0)
 		return 1;
+
+	tree_mod_log_write_lock(fs_info);
+	if (list_empty(&(fs_info)->tree_mod_seq_list)) {
+		tree_mod_log_write_unlock(fs_info);
+		return 1;
+	}
+
 	return 0;
 }
 
-static inline int
-__tree_mod_log_insert_key(struct btrfs_fs_info *fs_info,
-			  struct extent_buffer *eb, int slot,
-			  enum mod_log_op op, gfp_t flags)
+/* Similar to tree_mod_dont_log, but doesn't acquire any locks. */
+static inline int tree_mod_need_log(const struct btrfs_fs_info *fs_info,
+				    struct extent_buffer *eb)
+{
+	smp_mb();
+	if (list_empty(&(fs_info)->tree_mod_seq_list))
+		return 0;
+	if (eb && btrfs_header_level(eb) == 0)
+		return 0;
+
+	return 1;
+}
+
+static struct tree_mod_elem *
+alloc_tree_mod_elem(struct extent_buffer *eb, int slot,
+		    enum mod_log_op op, gfp_t flags)
 {
 	struct tree_mod_elem *tm;
 
 	tm = kzalloc(sizeof(*tm), flags);
 	if (!tm)
-		return -ENOMEM;
+		return NULL;
 
 	tm->index = eb->start >> PAGE_CACHE_SHIFT;
 	if (op != MOD_LOG_KEY_ADD) {
···
 	tm->op = op;
 	tm->slot = slot;
 	tm->generation = btrfs_node_ptr_generation(eb, slot);
+	RB_CLEAR_NODE(&tm->node);
 
-	return __tree_mod_log_insert(fs_info, tm);
+	return tm;
 }
 
 static noinline int
···
 			struct extent_buffer *eb, int slot,
 			enum mod_log_op op, gfp_t flags)
 {
-	if (tree_mod_dont_log(fs_info, eb))
+	struct tree_mod_elem *tm;
+	int ret;
+
+	if (!tree_mod_need_log(fs_info, eb))
 		return 0;
 
-	return __tree_mod_log_insert_key(fs_info, eb, slot, op, flags);
+	tm = alloc_tree_mod_elem(eb, slot, op, flags);
+	if (!tm)
+		return -ENOMEM;
+
+	if (tree_mod_dont_log(fs_info, eb)) {
+		kfree(tm);
+		return 0;
+	}
+
+	ret = __tree_mod_log_insert(fs_info, tm);
+	tree_mod_log_write_unlock(fs_info);
+	if (ret)
+		kfree(tm);
+
+	return ret;
 }
 
 static noinline int
···
 			 struct extent_buffer *eb, int dst_slot, int src_slot,
 			 int nr_items, gfp_t flags)
 {
-	struct tree_mod_elem *tm;
-	int ret;
+	struct tree_mod_elem *tm = NULL;
+	struct tree_mod_elem **tm_list = NULL;
+	int ret = 0;
 	int i;
+	int locked = 0;
 
-	if (tree_mod_dont_log(fs_info, eb))
+	if (!tree_mod_need_log(fs_info, eb))
 		return 0;
 
-	/*
-	 * When we override something during the move, we log these removals.
-	 * This can only happen when we move towards the beginning of the
-	 * buffer, i.e. dst_slot < src_slot.
-	 */
-	for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
-		ret = __tree_mod_log_insert_key(fs_info, eb, i + dst_slot,
-				MOD_LOG_KEY_REMOVE_WHILE_MOVING, GFP_NOFS);
-		BUG_ON(ret < 0);
-	}
+	tm_list = kzalloc(nr_items * sizeof(struct tree_mod_elem *), flags);
+	if (!tm_list)
+		return -ENOMEM;
 
 	tm = kzalloc(sizeof(*tm), flags);
-	if (!tm)
-		return -ENOMEM;
+	if (!tm) {
+		ret = -ENOMEM;
+		goto free_tms;
+	}
 
 	tm->index = eb->start >> PAGE_CACHE_SHIFT;
 	tm->slot = src_slot;
···
 	tm->move.nr_items = nr_items;
 	tm->op = MOD_LOG_MOVE_KEYS;
 
-	return __tree_mod_log_insert(fs_info, tm);
+	for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
+		tm_list[i] = alloc_tree_mod_elem(eb, i + dst_slot,
+		    MOD_LOG_KEY_REMOVE_WHILE_MOVING, flags);
+		if (!tm_list[i]) {
+			ret = -ENOMEM;
+			goto free_tms;
+		}
+	}
+
+	if (tree_mod_dont_log(fs_info, eb))
+		goto free_tms;
+	locked = 1;
+
+	/*
+	 * When we override something during the move, we log these removals.
+	 * This can only happen when we move towards the beginning of the
+	 * buffer, i.e. dst_slot < src_slot.
+	 */
+	for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
+		ret = __tree_mod_log_insert(fs_info, tm_list[i]);
+		if (ret)
+			goto free_tms;
+	}
+
+	ret = __tree_mod_log_insert(fs_info, tm);
+	if (ret)
+		goto free_tms;
+	tree_mod_log_write_unlock(fs_info);
+	kfree(tm_list);
+
+	return 0;
+free_tms:
+	for (i = 0; i < nr_items; i++) {
+		if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
+			rb_erase(&tm_list[i]->node, &fs_info->tree_mod_log);
+		kfree(tm_list[i]);
+	}
+	if (locked)
+		tree_mod_log_write_unlock(fs_info);
+	kfree(tm_list);
+	kfree(tm);
+
+	return ret;
 }
 
-static inline void
-__tree_mod_log_free_eb(struct btrfs_fs_info *fs_info, struct extent_buffer *eb)
+static inline int
+__tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
+		       struct tree_mod_elem **tm_list,
+		       int nritems)
 {
-	int i;
-	u32 nritems;
+	int i, j;
 	int ret;
 
-	if (btrfs_header_level(eb) == 0)
-		return;
-
-	nritems = btrfs_header_nritems(eb);
 	for (i = nritems - 1; i >= 0; i--) {
-		ret = __tree_mod_log_insert_key(fs_info, eb, i,
-				MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
-		BUG_ON(ret < 0);
+		ret = __tree_mod_log_insert(fs_info, tm_list[i]);
+		if (ret) {
+			for (j = nritems - 1; j > i; j--)
+				rb_erase(&tm_list[j]->node,
+					 &fs_info->tree_mod_log);
+			return ret;
+		}
 	}
+
+	return 0;
 }
 
 static noinline int
···
 			 struct extent_buffer *new_root, gfp_t flags,
 			 int log_removal)
 {
-	struct tree_mod_elem *tm;
+	struct tree_mod_elem *tm = NULL;
+	struct tree_mod_elem **tm_list = NULL;
+	int nritems = 0;
+	int ret = 0;
+	int i;
 
-	if (tree_mod_dont_log(fs_info, NULL))
+	if (!tree_mod_need_log(fs_info, NULL))
 		return 0;
 
-	if (log_removal)
-		__tree_mod_log_free_eb(fs_info, old_root);
+	if (log_removal && btrfs_header_level(old_root) > 0) {
+		nritems = btrfs_header_nritems(old_root);
+		tm_list = kzalloc(nritems * sizeof(struct tree_mod_elem *),
+				  flags);
+		if (!tm_list) {
+			ret = -ENOMEM;
+			goto free_tms;
+		}
+		for (i = 0; i < nritems; i++) {
+			tm_list[i] = alloc_tree_mod_elem(old_root, i,
+			    MOD_LOG_KEY_REMOVE_WHILE_FREEING, flags);
+			if (!tm_list[i]) {
+				ret = -ENOMEM;
+				goto free_tms;
+			}
+		}
+	}
 
 	tm = kzalloc(sizeof(*tm), flags);
-	if (!tm)
-		return -ENOMEM;
+	if (!tm) {
+		ret = -ENOMEM;
+		goto free_tms;
+	}
 
 	tm->index = new_root->start >> PAGE_CACHE_SHIFT;
 	tm->old_root.logical = old_root->start;
···
 	tm->generation = btrfs_header_generation(old_root);
 	tm->op = MOD_LOG_ROOT_REPLACE;
 
-	return __tree_mod_log_insert(fs_info, tm);
+	if (tree_mod_dont_log(fs_info, NULL))
+		goto free_tms;
+
+	if (tm_list)
+		ret = __tree_mod_log_free_eb(fs_info, tm_list, nritems);
+	if (!ret)
+		ret = __tree_mod_log_insert(fs_info, tm);
+
+	tree_mod_log_write_unlock(fs_info);
+	if (ret)
+		goto free_tms;
+	kfree(tm_list);
+
+	return ret;
+
+free_tms:
+	if (tm_list) {
+		for (i = 0; i < nritems; i++)
+			kfree(tm_list[i]);
+		kfree(tm_list);
+	}
+	kfree(tm);
+
+	return ret;
 }
 
 static struct tree_mod_elem *
···
 	return __tree_mod_log_search(fs_info, start, min_seq, 0);
 }
 
-static noinline void
+static noinline int
 tree_mod_log_eb_copy(struct btrfs_fs_info *fs_info, struct extent_buffer *dst,
 		     struct extent_buffer *src, unsigned long dst_offset,
 		     unsigned long src_offset, int nr_items)
 {
-	int ret;
+	int ret = 0;
+	struct tree_mod_elem **tm_list = NULL;
+	struct tree_mod_elem **tm_list_add, **tm_list_rem;
 	int i;
+	int locked = 0;
 
-	if (tree_mod_dont_log(fs_info, NULL))
-		return;
+	if (!tree_mod_need_log(fs_info, NULL))
+		return 0;
 
 	if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0)
-		return;
+		return 0;
+
+	tm_list = kzalloc(nr_items * 2 * sizeof(struct tree_mod_elem *),
+			  GFP_NOFS);
+	if (!tm_list)
+		return -ENOMEM;
+
+	tm_list_add = tm_list;
+	tm_list_rem = tm_list + nr_items;
+	for (i = 0; i < nr_items; i++) {
+		tm_list_rem[i] = alloc_tree_mod_elem(src, i + src_offset,
+		    MOD_LOG_KEY_REMOVE, GFP_NOFS);
+		if (!tm_list_rem[i]) {
+			ret = -ENOMEM;
+			goto free_tms;
+		}
+
+		tm_list_add[i] = alloc_tree_mod_elem(dst, i + dst_offset,
+		    MOD_LOG_KEY_ADD, GFP_NOFS);
+		if (!tm_list_add[i]) {
+			ret = -ENOMEM;
+			goto free_tms;
+		}
+	}
+
+	if (tree_mod_dont_log(fs_info, NULL))
+		goto free_tms;
+	locked = 1;
 
 	for (i = 0; i < nr_items; i++) {
-		ret = __tree_mod_log_insert_key(fs_info, src,
-						i + src_offset,
-						MOD_LOG_KEY_REMOVE, GFP_NOFS);
-		BUG_ON(ret < 0);
-		ret = __tree_mod_log_insert_key(fs_info, dst,
-						     i + dst_offset,
-						     MOD_LOG_KEY_ADD,
-						     GFP_NOFS);
-		BUG_ON(ret < 0);
+		ret = __tree_mod_log_insert(fs_info, tm_list_rem[i]);
+		if (ret)
+			goto free_tms;
+		ret = __tree_mod_log_insert(fs_info, tm_list_add[i]);
+		if (ret)
+			goto free_tms;
 	}
+
+	tree_mod_log_write_unlock(fs_info);
+	kfree(tm_list);
+
+	return 0;
+
+free_tms:
+	for (i = 0; i < nr_items * 2; i++) {
+		if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
+			rb_erase(&tm_list[i]->node, &fs_info->tree_mod_log);
+		kfree(tm_list[i]);
+	}
+	if (locked)
+		tree_mod_log_write_unlock(fs_info);
+	kfree(tm_list);
+
+	return ret;
 }
 
 static inline void
···
 	BUG_ON(ret < 0);
 }
 
-static noinline void
+static noinline int
 tree_mod_log_free_eb(struct btrfs_fs_info *fs_info, struct extent_buffer *eb)
 {
+	struct tree_mod_elem **tm_list = NULL;
+	int nritems = 0;
+	int i;
+	int ret = 0;
+
+	if (btrfs_header_level(eb) == 0)
+		return 0;
+
+	if (!tree_mod_need_log(fs_info, NULL))
+		return 0;
+
+	nritems = btrfs_header_nritems(eb);
+	tm_list = kzalloc(nritems * sizeof(struct tree_mod_elem *),
+			  GFP_NOFS);
+	if (!tm_list)
+		return -ENOMEM;
+
+	for (i = 0; i < nritems; i++) {
+		tm_list[i] = alloc_tree_mod_elem(eb, i,
+		    MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
+		if (!tm_list[i]) {
+			ret = -ENOMEM;
+			goto free_tms;
+		}
+	}
+
 	if (tree_mod_dont_log(fs_info, eb))
-		return;
-	__tree_mod_log_free_eb(fs_info, eb);
+		goto free_tms;
+
+	ret = __tree_mod_log_free_eb(fs_info, tm_list, nritems);
+	tree_mod_log_write_unlock(fs_info);
+	if (ret)
+		goto free_tms;
+	kfree(tm_list);
+
+	return 0;
+
+free_tms:
+	for (i = 0; i < nritems; i++)
+		kfree(tm_list[i]);
+	kfree(tm_list);
+
+	return ret;
 }
 
 static noinline void
···
 		btrfs_set_node_ptr_generation(parent, parent_slot,
 					      trans->transid);
 		btrfs_mark_buffer_dirty(parent);
-		if (last_ref)
-			tree_mod_log_free_eb(root->fs_info, buf);
+		if (last_ref) {
+			ret = tree_mod_log_free_eb(root->fs_info, buf);
+			if (ret) {
+				btrfs_abort_transaction(trans, root, ret);
+				return ret;
+			}
+		}
 		btrfs_free_tree_block(trans, root, buf, parent_start,
 				      last_ref);
 	}
···
 	} else
 		push_items = min(src_nritems - 8, push_items);
 
-	tree_mod_log_eb_copy(root->fs_info, dst, src, dst_nritems, 0,
-			     push_items);
+	ret = tree_mod_log_eb_copy(root->fs_info, dst, src, dst_nritems, 0,
+				   push_items);
+	if (ret) {
+		btrfs_abort_transaction(trans, root, ret);
+		return ret;
+	}
 	copy_extent_buffer(dst, src,
 			   btrfs_node_key_ptr_offset(dst_nritems),
 			   btrfs_node_key_ptr_offset(0),
···
 				      (dst_nritems) *
 				      sizeof(struct btrfs_key_ptr));
 
-	tree_mod_log_eb_copy(root->fs_info, dst, src, 0,
-			     src_nritems - push_items, push_items);
+	ret = tree_mod_log_eb_copy(root->fs_info, dst, src, 0,
+				   src_nritems - push_items, push_items);
+	if (ret) {
+		btrfs_abort_transaction(trans, root, ret);
+		return ret;
+	}
 	copy_extent_buffer(dst, src,
 			   btrfs_node_key_ptr_offset(0),
 			   btrfs_node_key_ptr_offset(src_nritems - push_items),
···
 			    btrfs_header_chunk_tree_uuid(split),
 			    BTRFS_UUID_SIZE);
 
-	tree_mod_log_eb_copy(root->fs_info, split, c, 0, mid, c_nritems - mid);
+	ret = tree_mod_log_eb_copy(root->fs_info, split, c, 0,
+				   mid, c_nritems - mid);
+	if (ret) {
+		btrfs_abort_transaction(trans, root, ret);
+		return ret;
+	}
 	copy_extent_buffer(split, c,
 			   btrfs_node_key_ptr_offset(0),
 			   btrfs_node_key_ptr_offset(mid),