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>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index c79ddc7..19b4db7 100644 (file)
--- 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);
 

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 1791c6e..59e0203 100644 (file)
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1221,6 +1221,10 @@ static void cleanup_transaction(struct btrfs_trans_handle *trans,
 
        spin_lock(&root->fs_info->trans_lock);
        list_del_init(&cur_trans->list);
+       if (cur_trans == root->fs_info->running_transaction) {
+               root->fs_info->running_transaction = NULL;
+               root->fs_info->trans_no_join = 0;
+       }
        spin_unlock(&root->fs_info->trans_lock);
 
        btrfs_cleanup_one_transaction(trans->transaction, root);