diff options
| -rw-r--r-- | fs/btrfs/locking.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c index 508a3fdfcd58..72992e74c479 100644 --- a/fs/btrfs/locking.c +++ b/fs/btrfs/locking.c @@ -364,8 +364,12 @@ void btrfs_drew_write_lock(struct btrfs_drew_lock *lock) void btrfs_drew_write_unlock(struct btrfs_drew_lock *lock) { - atomic_dec(&lock->writers); - cond_wake_up(&lock->pending_readers); + /* + * atomic_dec_and_test() implies a full barrier, so woken up readers are + * guaranteed to see the decrement. + */ + if (atomic_dec_and_test(&lock->writers)) + wake_up(&lock->pending_readers); } void btrfs_drew_read_lock(struct btrfs_drew_lock *lock) |