[PATCH 5.15 v2 0/1] ext4: backport online resize fix

[PATCH 5.15 v2 0/1] ext4: backport online resize fix

[Oleksandr Tymoshenko]

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

[PATCH 5.15 v2 1/1] ext4: fix bad checksum after online resize

[Oleksandr Tymoshenko]

From: Baokun Li <libaokun1@huawei.com>

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.

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@huawei.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20221117040341.1380702-2-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Oleksandr Tymoshenko <ovt@google.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 405c68085055..589ed99856f3 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,
-- 
2.39.1.456.gfc5497dd1b-goog

Re: [PATCH 5.15 v2 1/1] ext4: fix bad checksum after online resize

[Sasha Levin]

On Mon, Jan 30, 2023 at 11:52:12PM +0000, Oleksandr Tymoshenko wrote:
>From: Baokun Li <libaokun1@huawei.com>
>
>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.
>
>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@huawei.com>
>Reviewed-by: Darrick J. Wong <djwong@kernel.org>
>Reviewed-by: Jan Kara <jack@suse.cz>
>Cc: stable@kernel.org
>Link: https://lore.kernel.org/r/20221117040341.1380702-2-libaokun1@huawei.com
>Signed-off-by: Theodore Ts'o <tytso@mit.edu>
>Signed-off-by: Oleksandr Tymoshenko <ovt@google.com>

I've grabbed it, thanks!

-- 
Thanks,
Sasha