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| author | Nikolay Borisov <nborisov@suse.com> | 2017-08-01 18:25:56 +0300 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2017-08-21 18:49:21 +0200 |
| commit | dc59215d4f42084ee13654bafe3e5130b146aeb7 (patch) | |
| tree | 3a94053e30f88d9064f79a3afe5ffdcc937ab309 | |
| parent | b5d9071c4f5c087614eb477bff04795e325bea70 (diff) | |
| download | linux-dc59215d4f42084ee13654bafe3e5130b146aeb7.tar.bz2 | |
btrfs: remove unnecessary memory barrier in btrfs_direct_IO
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.
Specifically for inode::i_dio_count that's wrapped inside
inode_dio_begin, there is no explicit barrier semantics attached, so
removing is fine as the atomic is used in common the waiter/wakeup
pattern.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ enhance changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
| -rw-r--r-- | fs/btrfs/inode.c | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 61f1ad89e97a..d184a46e46c4 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -8815,7 +8815,6 @@ 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 |