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authorJosef Bacik <jbacik@fusionio.com>2012-08-01 15:36:24 -0400
committerChris Mason <chris.mason@oracle.com>2012-08-28 16:53:33 -0400
commit66657b318e0e443ada229fccd40c8be86cfebdbf (patch)
treebf1334fff93556fbc8d82b26a6d5431fd9e74b5c /fs/btrfs/delayed-inode.c
parent1fa11e265fa2562fb713171b6a58e72bb7afd276 (diff)
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 <jbacik@fusionio.com>
Diffstat (limited to 'fs/btrfs/delayed-inode.c')
-rw-r--r--fs/btrfs/delayed-inode.c7
1 files changed, 3 insertions, 4 deletions
diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index 00deed4ef3ed..07d5eeb1e6f1 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -512,8 +512,8 @@ static void __btrfs_remove_delayed_item(struct btrfs_delayed_item *delayed_item)
rb_erase(&delayed_item->rb_node, root);
delayed_item->delayed_node->count--;
- atomic_dec(&delayed_root->items);
- if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND &&
+ if (atomic_dec_return(&delayed_root->items) <
+ BTRFS_DELAYED_BACKGROUND &&
waitqueue_active(&delayed_root->wait))
wake_up(&delayed_root->wait);
}
@@ -1056,8 +1056,7 @@ static void btrfs_release_delayed_inode(struct btrfs_delayed_node *delayed_node)
delayed_node->count--;
delayed_root = delayed_node->root->fs_info->delayed_root;
- atomic_dec(&delayed_root->items);
- if (atomic_read(&delayed_root->items) <
+ if (atomic_dec_return(&delayed_root->items) <
BTRFS_DELAYED_BACKGROUND &&
waitqueue_active(&delayed_root->wait))
wake_up(&delayed_root->wait);