btrfs: update barrier in should_cow_block
Once there was a simple int force_cow that was used with the plain
barriers, and then converted to a bit, so we should use the appropriate
barrier helper.
Other variables in the complex if condition do not depend on a barrier,
so we should be fine in case the atomic barrier becomes a no-op.
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 7c8faeb..a2c9d21 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1441,8 +1441,8 @@
if (btrfs_is_testing(root->fs_info))
return 0;
- /* ensure we can see the force_cow */
- smp_rmb();
+ /* Ensure we can see the FORCE_COW bit */
+ smp_mb__before_atomic();
/*
* We do not need to cow a block if