ext4: Fix BUG_ON at fs/buffer.c:652 in no journal mode

Calls to ext4_handle_dirty_metadata should only pass in an inode
pointer for inode-specific metadata, and not for shared metadata
blocks such as inode table blocks, block group descriptors, the
superblock, etc.

The BUG_ON can get tripped when updating a special device (such as a
block device) that is opened (so that i_mapping is set in
fs/block_dev.c) and the file system is mounted in no journal mode.

Addresses-Google-Bug: #2404870

Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index bd2dc0b..a13948f 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2017,7 +2017,7 @@
 	/* Insert this inode at the head of the on-disk orphan list... */
 	NEXT_ORPHAN(inode) = le32_to_cpu(EXT4_SB(sb)->s_es->s_last_orphan);
 	EXT4_SB(sb)->s_es->s_last_orphan = cpu_to_le32(inode->i_ino);
-	err = ext4_handle_dirty_metadata(handle, inode, EXT4_SB(sb)->s_sbh);
+	err = ext4_handle_dirty_metadata(handle, NULL, EXT4_SB(sb)->s_sbh);
 	rc = ext4_mark_iloc_dirty(handle, inode, &iloc);
 	if (!err)
 		err = rc;
@@ -2089,7 +2089,7 @@
 		if (err)
 			goto out_brelse;
 		sbi->s_es->s_last_orphan = cpu_to_le32(ino_next);
-		err = ext4_handle_dirty_metadata(handle, inode, sbi->s_sbh);
+		err = ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
 	} else {
 		struct ext4_iloc iloc2;
 		struct inode *i_prev =