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authorChris Mason <clm@fb.com>2015-10-13 02:24:40 +0300
committerChris Mason <clm@fb.com>2015-10-13 02:24:40 +0300
commit6db4a7335dd701a0e20275440ee057d3db2a7ae3 (patch)
treec0734d7411806ef91bfeb615bf528ffb349938fe /fs/btrfs/inode.c
parent62fb50ab7c903357c92cef2f7677235b92ac575f (diff)
parentee86395458072760d62e66aad10a5e9e8902b8cf (diff)
downloadlinux-6db4a7335dd701a0e20275440ee057d3db2a7ae3.tar.xz
Merge branch 'fix/waitqueue-barriers' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux into for-linus-4.4
Diffstat (limited to 'fs/btrfs/inode.c')
-rw-r--r--fs/btrfs/inode.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 25eb814c302f..208db4e835f0 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1096,6 +1096,9 @@ static noinline void async_cow_submit(struct btrfs_work *work)
nr_pages = (async_cow->end - async_cow->start + PAGE_CACHE_SIZE) >>
PAGE_CACHE_SHIFT;
+ /*
+ * atomic_sub_return implies a barrier for waitqueue_active
+ */
if (atomic_sub_return(nr_pages, &root->fs_info->async_delalloc_pages) <
5 * 1024 * 1024 &&
waitqueue_active(&root->fs_info->async_submit_wait))