btrfs: fix deadlock in delayed_ref_async_start
"Btrfs: track transid for delayed ref flushing" was deadlocking on
btrfs_attach_transaction because its not safe to call from the async
delayed ref start code. This commit brings back btrfs_join_transaction
instead and checks for a blocked commit.
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index ecfa520..82b912a 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2851,16 +2851,13 @@
async = container_of(work, struct async_delayed_refs, work);
- trans = btrfs_attach_transaction(async->root);
- if (IS_ERR(trans)) {
- if (PTR_ERR(trans) != -ENOENT)
- async->error = PTR_ERR(trans);
+ /* if the commit is already started, we don't need to wait here */
+ if (btrfs_transaction_blocked(async->root->fs_info))
goto done;
- }
- /* Don't bother flushing if we got into a different transaction */
- if (trans->transid != async->transid) {
- btrfs_end_transaction(trans, async->root);
+ trans = btrfs_join_transaction(async->root);
+ if (IS_ERR(trans)) {
+ async->error = PTR_ERR(trans);
goto done;
}
@@ -2869,10 +2866,15 @@
* wait on delayed refs
*/
trans->sync = true;
+
+ /* Don't bother flushing if we got into a different transaction */
+ if (trans->transid > async->transid)
+ goto end;
+
ret = btrfs_run_delayed_refs(trans, async->root, async->count);
if (ret)
async->error = ret;
-
+end:
ret = btrfs_end_transaction(trans, async->root);
if (ret && !async->error)
async->error = ret;