ext4: Suppress sporadic error messages

Supress the sporadic "ext4_writepages: jbd2_start: XXX pages, ino YYY;
err -5" warnings we sometimes get when mxqd tries to unmount the
temporary job filesystems using

- fcntl EXT4_IOC_SHUTDOWN with EXT4_GOING_FLAGS_NOLOGFLUSH
- dmestup reload $dmname --table "0 $sectors zero"
- dmsetup resume $dmname --noflush
- umount $mountpoint
- dmsetup remove --deferred $dmname
- rmdir $mountpoint

fs/ext4/inode.c

@@ -2797,9 +2797,10 @@ static int ext4_writepages(struct address_space *mapping,
 				EXT4_HT_WRITE_PAGE, needed_blocks, rsv_blocks);
 		if (IS_ERR(handle)) {
 			ret = PTR_ERR(handle);
-			ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
-			       "%ld pages, ino %lu; err %d", __func__,
-				wbc->nr_to_write, inode->i_ino, ret);
+			if (!unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
+				ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
+						"%ld pages, ino %lu; err %d", __func__,
+						wbc->nr_to_write, inode->i_ino, ret);
 			/* Release allocated io_end */
 			ext4_put_io_end(mpd.io_submit.io_end);
 			mpd.io_submit.io_end = NULL;