jbd2: Reorganize jbd2_journal_stop()

Move code in jbd2_journal_stop() around a bit. It removes some
unnecessary code duplication and will make factoring out parts common
with jbd2__journal_restart() easier.
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20191105164437.32602-14-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/jbd2/transaction.c

@@ -1706,41 +1706,34 @@ int jbd2_journal_stop(handle_t *handle)
 	tid_t tid;
 	pid_t pid;
 
-	if (!transaction) {
-		/*
-		 * Handle is already detached from the transaction so
-		 * there is nothing to do other than decrease a refcount,
-		 * or free the handle if refcount drops to zero
-		 */
 	if (--handle->h_ref > 0) {
 		jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
 						 handle->h_ref);
-			return err;
-		} else {
+		if (is_handle_aborted(handle))
+			return -EIO;
+		return 0;
+	}
+	if (!transaction) {
+		/*
+		 * Handle is already detached from the transaction so there is
+		 * nothing to do other than free the handle.
+		 */
 		if (handle->h_rsv_handle)
 			jbd2_free_handle(handle->h_rsv_handle);
 		goto free_and_exit;
 	}
-	}
 	journal = transaction->t_journal;
+	tid = transaction->t_tid;
 
 	J_ASSERT(journal_current_handle() == handle);
+	J_ASSERT(atomic_read(&transaction->t_updates) > 0);
 
 	if (is_handle_aborted(handle))
 		err = -EIO;
-	else
-		J_ASSERT(atomic_read(&transaction->t_updates) > 0);
-
-	if (--handle->h_ref > 0) {
-		jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
-			  handle->h_ref);
-		return err;
-	}
 
 	jbd_debug(4, "Handle %p going down\n", handle);
 	trace_jbd2_handle_stats(journal->j_fs_dev->bd_dev,
-				transaction->t_tid,
-				handle->h_type, handle->h_line_no,
+				tid, handle->h_type, handle->h_line_no,
 				jiffies - handle->h_start_jiffies,
 				handle->h_sync, handle->h_requested_credits,
 				(handle->h_requested_credits -
@@ -1825,7 +1818,7 @@ int jbd2_journal_stop(handle_t *handle)
 		jbd_debug(2, "transaction too old, requesting commit for "
 					"handle %p\n", handle);
 		/* This is non-blocking */
-		jbd2_log_start_commit(journal, transaction->t_tid);
+		jbd2_log_start_commit(journal, tid);
 
 		/*
 		 * Special case: JBD2_SYNC synchronous updates require us
@@ -1841,7 +1834,6 @@ int jbd2_journal_stop(handle_t *handle)
 	 * once we do this, we must not dereference transaction
 	 * pointer again.
 	 */
-	tid = transaction->t_tid;
 	if (atomic_dec_and_test(&transaction->t_updates)) {
 		wake_up(&journal->j_wait_updates);
 		if (journal->j_barrier_count)