Btrfs: wake up transaction waiters when aborting a transaction

I was getting lots of hung tasks and a NULL pointer dereference because we
are not cleaning up the transaction properly when it aborts.  First we need
to reset the running_transaction to NULL so we don't get a bad dereference
for any start_transaction callers after this.  Also we cannot rely on
waitqueue_active() since it's just a list_empty(), so just call wake_up()
directly since that will do the barrier for us and such.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>

1 files changed, 3 insertions, 6 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index c79ddc756081..19b4db70dcb1 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3589,16 +3589,13 @@ void btrfs_cleanup_one_transaction(struct btrfs_transaction *cur_trans,
         /* FIXME: cleanup wait for commit */
         cur_trans->in_commit = 1;
         cur_trans->blocked = 1;
-        if (waitqueue_active(&root->fs_info->transaction_blocked_wait))
-                wake_up(&root->fs_info->transaction_blocked_wait);
+        wake_up(&root->fs_info->transaction_blocked_wait);
 
         cur_trans->blocked = 0;
-        if (waitqueue_active(&root->fs_info->transaction_wait))
-                wake_up(&root->fs_info->transaction_wait);
+        wake_up(&root->fs_info->transaction_wait);
 
         cur_trans->commit_done = 1;
-        if (waitqueue_active(&cur_trans->commit_wait))
-                wake_up(&cur_trans->commit_wait);
+        wake_up(&cur_trans->commit_wait);
 
         btrfs_destroy_pending_snapshots(cur_trans);