[PATCH 6.18 290/333] btrfs: add missing RCU unlock in error path in try_release_subpage_extent_buffer()

Greg Kroah-Hartman
2026-03-17T17:25:50Z

From: Bart Van Assche <bvanassche@acm.org>

commit b2840e33127ce0eea880504b7f133e780f567a9b upstream.

Call rcu_read_lock() before exiting the loop in
try_release_subpage_extent_buffer() because there is a rcu_read_unlock()
call past the loop.

This has been detected by the Clang thread-safety analyzer.

Fixes: ad580dfa388f ("btrfs: fix subpage deadlock in try_release_subpage_extent_buffer()")
CC: stable@vger.kernel.org # 6.18+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/btrfs/extent_io.c | 1 +
1 file changed, 1 insertion(+)

--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4478,6 +4478,7 @@ static int try_release_subpage_extent_bu
*/
if (!test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) {
spin_unlock(&eb->refs_lock);
+ rcu_read_lock();
break;
}