[PATCH 1/4] ext4: fix bad checksum after online resize

[Khalid Elmously]

From: Baokun Li <libaokun1 at huawei.com>

BugLink: https://bugs.launchpad.net/bugs/2003816

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.

Fixes: 026d0d27c488 ("ext4: reduce computation of overhead during resize")
Fixes: de394a86658f ("ext4: update s_overhead_clusters in the superblock during an on-line resize")
Signed-off-by: Baokun Li <libaokun1 at huawei.com>
Reviewed-by: Darrick J. Wong <djwong at kernel.org>
Reviewed-by: Jan Kara <jack at suse.cz>
Cc: stable at kernel.org
Link: https://lore.kernel.org/r/20221117040341.1380702-2-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso at mit.edu>
(cherry picked from commit a408f33e895e455f16cf964cb5cd4979b658db7b)
Signed-off-by: Khalid Elmously <khalid.elmously at canonical.com>
---
 fs/ext4/resize.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 62bbfe8960f3b..58fb108a81cc6 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -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,
-- 
2.34.1