ext4: backport online resize fix

The following patch is required to fix the ext4 online resize in 5.15.

Baokun Li (1):
ext4: fix bad checksum after online resize

 fs/ext4/resize.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

2.39.1.456.gfc5497dd1b-goog

From: Baokun Li <[email protected]>

commit a408f33e895e455f16cf964cb5cd4979b658db7b upstream.

When online resizing is performed twice consecutively, the error message "Superblock checksum does not match superblock" is displayed for the second time. Here's the reproducer:

mkfs.ext4 -F /dev/sdb 100M
mount /dev/sdb /tmp/test
resize2fs /dev/sdb 5G
resize2fs /dev/sdb 6G

To solve this issue, we moved the update of the checksum after the es->s_overhead_clusters is updated.

---
 fs/ext4/resize.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

index 405c68085055..589ed99856f3 100644
@@ -1445,8 +1445,6 @@ static void ext4_update_super(struct super_block *sb,
 	 * active. */
 	ext4_r_blocks_count_set(es, ext4_r_blocks_count(es) +
 				reserved_blocks);
-	ext4_superblock_csum_set(sb);
-	unlock_buffer(sbi->s_sbh);
 
 	/* Update the free space counts */
 	percpu_counter_add(&sbi->s_freeclusters_counter,

@@ -1474,6 +1472,8 @@ static void ext4_update_super(struct super_block *sb,
 	ext4_calculate_overhead(sb);
 	es->s_overhead_clusters = cpu_to_le32(sbi->s_overhead);
 
+	ext4_superblock_csum_set(sb);
+	unlock_buffer(sbi->s_sbh);
 	if (test_opt(sb, DEBUG))
 		printk(KERN_DEBUG "EXT4-fs: added group %u:"
 		       "%llu blocks(%llu free %llu reserved)\n", flex_gd->count,

2.39.1.456.gfc5497dd1b-goog

I've grabbed it, thanks!

Thanks,
Sasha