Commit 38851cc19adb ("Btrfs: implement unlocked dio write") implemented
unlocked dio write, allowing multiple dio writers to write to non-overlapping,
and non-eof-extending regions. In doing so it also introduced a broken memory
barrier. It is broken due to 2 things:
1. Memory barriers _MUST_ always be paired, this is clearly not the case here
2. Checkpatch actually produces a warning if a memory barrier is introduced that
doesn't have a comment explaining how it's being paired.
Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
---
fs/btrfs/inode.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 95c212037095..5e48d2c10152 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8731,7 +8731,6 @@ static ssize_t btrfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
return 0;
inode_dio_begin(inode);
- smp_mb__after_atomic();
/*
* The generic stuff only does filemap_write_and_wait_range, which
--
2.7.4
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
