ext4: fix super block checksum incorrect after mount

We got issue as follows:
[home]# mount  /dev/sda  test
EXT4-fs (sda): warning: mounting fs with errors, running e2fsck is recommended
[home]# dmesg
EXT4-fs (sda): warning: mounting fs with errors, running e2fsck is recommended
EXT4-fs (sda): Errors on filesystem, clearing orphan list.
EXT4-fs (sda): recovery complete
EXT4-fs (sda): mounted filesystem with ordered data mode. Quota mode: none.
[home]# debugfs /dev/sda
debugfs 1.46.5 (30-Dec-2021)
Checksum errors in superblock!  Retrying...

Reason is ext4_orphan_cleanup will reset ‘s_last_orphan’ but not update
super block checksum.

To solve above issue, defer update super block checksum after
ext4_orphan_cleanup.

Signed-off-by: Ye Bin <[email protected]>
Cc: [email protected]
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Ritesh Harjani <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Theodore Ts'o <[email protected]>

Author: Ye Bin

fs/ext4/super.c

@@ -5302,14 +5302,6 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
 		err = percpu_counter_init(&sbi->s_freeinodes_counter, freei,
 					  GFP_KERNEL);
 	}
-	/*
-	 * Update the checksum after updating free space/inode
-	 * counters.  Otherwise the superblock can have an incorrect
-	 * checksum in the buffer cache until it is written out and
-	 * e2fsprogs programs trying to open a file system immediately
-	 * after it is mounted can fail.
-	 */
-	ext4_superblock_csum_set(sb);
 	if (!err)
 		err = percpu_counter_init(&sbi->s_dirs_counter,
 					  ext4_count_dirs(sb), GFP_KERNEL);
@@ -5367,6 +5359,14 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
 	EXT4_SB(sb)->s_mount_state |= EXT4_ORPHAN_FS;
 	ext4_orphan_cleanup(sb, es);
 	EXT4_SB(sb)->s_mount_state &= ~EXT4_ORPHAN_FS;
+	/*
+	 * Update the checksum after updating free space/inode counters and
+	 * ext4_orphan_cleanup. Otherwise the superblock can have an incorrect
+	 * checksum in the buffer cache until it is written out and
+	 * e2fsprogs programs trying to open a file system immediately
+	 * after it is mounted can fail.
+	 */
+	ext4_superblock_csum_set(sb);
 	if (needs_recovery) {
 		ext4_msg(sb, KERN_INFO, "recovery complete");
 		err = ext4_mark_recovery_complete(sb, es);