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authorNikolay Borisov <nborisov@suse.com>2017-08-01 18:25:56 +0300
committerDavid Sterba <dsterba@suse.com>2017-08-21 18:49:21 +0200
commitdc59215d4f42084ee13654bafe3e5130b146aeb7 (patch)
tree3a94053e30f88d9064f79a3afe5ffdcc937ab309 /fs/btrfs
parentb5d9071c4f5c087614eb477bff04795e325bea70 (diff)
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>
Diffstat (limited to 'fs/btrfs')
-rw-r--r--fs/btrfs/inode.c1
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