[PATCH 4/6] btrfs-progs: check/original: Fix uninitialized return value from btrfs_write_dirty_block_groups()

[Qu Wenruo <wqu@suse.com>]

[BUG]
Valgrind reports the following error for fsck/007, which is only
repairable for original mode:
  ==97599== Conditional jump or move depends on uninitialised value(s)
  ==97599==    at 0x1D4A42: btrfs_commit_transaction (transaction.c:207)
  ==97599==    by 0x16475C: check_extent_refs (main.c:8097)
  ==97599==    by 0x166199: check_chunks_and_extents (main.c:8786)
  ==97599==    by 0x166441: do_check_chunks_and_extents (main.c:8842)
  ==97599==    by 0x169D13: cmd_check (main.c:10324)
  ==97599==    by 0x11CDC6: cmd_execute (commands.h:125)
  ==97599==    by 0x11D712: main (btrfs.c:386)
  ==97599==

[CAUSE]
If btrfs_write_dirty_block_groups() get called with no block group
dirtied (no dirty extents created), the return value of it is
uninitialized, as the stack @ret is not initialized at all.

[FIX]
Initialize @ret to 0 for btrfs_write_dirty_block_groups() as if there is
no dirty block groups, we do nothing and shouldn't fail.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 extent-tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/extent-tree.c b/extent-tree.c
index dc4b052c1666..f0cb9faa4da6 100644
--- a/extent-tree.c
+++ b/extent-tree.c
@@ -1564,7 +1564,7 @@ int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans)
 {
 	struct btrfs_block_group_cache *cache;
 	struct btrfs_path *path;
-	int ret;
+	int ret = 0;
 
 	path = btrfs_alloc_path();
 	if (!path)
-- 
2.25.2