[PATCH 4.9 30/71] btrfs: Remove redundant extent_buffer_get in get_old_root

From: Greg Kroah-Hartman
Date: Fri Sep 11 2020 - 10:15:07 EST

From: Nikolay Borisov <nborisov@xxxxxxxx>

[ Upstream commit 6c122e2a0c515cfb3f3a9cefb5dad4cb62109c78 ]

get_old_root used used only by btrfs_search_old_slot to initialise the
path structure. The old root is always a cloned buffer (either via alloc
dummy or via btrfs_clone_extent_buffer) and its reference count is 2: 1
from allocation, 1 from extent_buffer_get call in get_old_root.

This latter explicit ref count acquire operation is in fact unnecessary
since the semantic is such that the newly allocated buffer is handed
over to the btrfs_path for lifetime management. Considering this just
remove the extra extent_buffer_get in get_old_root.

Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
fs/btrfs/ctree.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index b5ebb43b1824f..78d4c8c22b4ac 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1430,7 +1430,6 @@ get_old_root(struct btrfs_root *root, u64 time_seq)

if (!eb)
return NULL;
- extent_buffer_get(eb);
if (old_root) {
btrfs_set_header_bytenr(eb, eb->start);