From 66657b318e0e443ada229fccd40c8be86cfebdbf Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Wed, 1 Aug 2012 15:36:24 -0400 Subject: Btrfs: barrier before waitqueue_active We need a barrir before calling waitqueue_active otherwise we will miss wakeups. So in places that do atomic_dec(); then atomic_read() use atomic_dec_return() which imply a memory barrier (see memory-barriers.txt) and then add an explicit memory barrier everywhere else that need them. Thanks, Signed-off-by: Josef Bacik --- fs/btrfs/inode.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'fs/btrfs/inode.c') diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 2d65c52b094..97baf00b40d 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1007,9 +1007,7 @@ 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(nr_pages, &root->fs_info->async_delalloc_pages); - - if (atomic_read(&root->fs_info->async_delalloc_pages) < + if (atomic_sub_return(nr_pages, &root->fs_info->async_delalloc_pages) < 5 * 1024 * 1024 && waitqueue_active(&root->fs_info->async_submit_wait)) wake_up(&root->fs_info->async_submit_wait); -- cgit v1.2.3-70-g09d2