Btrfs: stop waiting on current trans if we aborted

I hit a hang when run_delayed_refs returned an error in the beginning of
btrfs_commit_transaction.  If we decide we need to commit the transaction in
btrfs_end_transaction we'll set BLOCKED and start to commit, but if we get an
error this early on we'll just exit without committing.  This is fine, except
that anybody else who tried to start a transaction will sit in
wait_current_trans() since we're set to BLOCKED and we never set it to something
else and woke people up.  To fix this we want to check for trans->aborted
everywhere we wait for the transaction state to change, and make
btrfs_abort_transaction() wake up any waiters there may be.  All the callers
will notice that the transaction has aborted and exit out properly.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>

fs/btrfs/super.c

@@ -265,6 +265,9 @@ void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
 		return;
 	}
 	ACCESS_ONCE(trans->transaction->aborted) = errno;
+	/* Wake up anybody who may be waiting on this transaction */
+	wake_up(&root->fs_info->transaction_wait);
+	wake_up(&root->fs_info->transaction_blocked_wait);
 	__btrfs_std_error(root->fs_info, function, line, errno, NULL);
 }
 /*

fs/btrfs/transaction.c

@@ -302,7 +302,8 @@ int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 static inline int is_transaction_blocked(struct btrfs_transaction *trans)
 {
 	return (trans->state >= TRANS_STATE_BLOCKED &&
-		trans->state < TRANS_STATE_UNBLOCKED);
+		trans->state < TRANS_STATE_UNBLOCKED &&
+		!trans->aborted);
 }
 
 /* wait for commit against the current transaction to become unblocked
@@ -320,7 +321,8 @@ static void wait_current_trans(struct btrfs_root *root)
 		spin_unlock(&root->fs_info->trans_lock);
 
 		wait_event(root->fs_info->transaction_wait,
-			   cur_trans->state >= TRANS_STATE_UNBLOCKED);
+			   cur_trans->state >= TRANS_STATE_UNBLOCKED ||
+			   cur_trans->aborted);
 		put_transaction(cur_trans);
 	} else {
 		spin_unlock(&root->fs_info->trans_lock);
@@ -1392,7 +1394,8 @@ static void wait_current_trans_commit_start(struct btrfs_root *root,
 					    struct btrfs_transaction *trans)
 {
 	wait_event(root->fs_info->transaction_blocked_wait,
-		   trans->state >= TRANS_STATE_COMMIT_START);
+		   trans->state >= TRANS_STATE_COMMIT_START ||
+		   trans->aborted);
 }
 
 /*
@@ -1403,7 +1406,8 @@ static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
 					 struct btrfs_transaction *trans)
 {
 	wait_event(root->fs_info->transaction_wait,
-		   trans->state >= TRANS_STATE_UNBLOCKED);
+		   trans->state >= TRANS_STATE_UNBLOCKED ||
+		   trans->aborted);
 }
 
 /*