From: Baokun Li libaokun1@huawei.com
commit 8f49ec603ae3e213bfab2799182724e3abac55a1 upstream.
In commit 9a8c5b0d0615 ("ext4: update the backup superblock's at the end of the online resize"), it is assumed that update_backups() only updates backup superblocks, so each b_data is treated as a backupsuper block to update its s_block_group_nr and s_checksum. However, update_backups() also updates the backup group descriptors, which causes the backup group descriptors to be corrupted.
The above commit fixes the problem of invalid checksum of the backup superblock. The root cause of this problem is that the checksum of ext4_update_super() is not set correctly. This problem has been fixed in the previous patch ("ext4: fix bad checksum after online resize").
However, we do need to set block_group_nr for the backup superblock in update_backups(). When a block is in a group that contains a backup superblock, and the block is the first block in the group, the block is definitely a superblock. We add a helper function that includes setting s_block_group_nr and updating checksum, and then call it only when the above conditions are met to prevent the backup group descriptors from being incorrectly modified.
Fixes: 9a8c5b0d0615 ("ext4: update the backup superblock's at the end of the online resize") Signed-off-by: Baokun Li libaokun1@huawei.com Reviewed-by: Jan Kara jack@suse.cz Cc: stable@kernel.org Link: https://lore.kernel.org/r/20221117040341.1380702-3-libaokun1@huawei.com Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ext4/resize.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-)
--- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -1110,6 +1110,16 @@ exit_free: return err; }
+static inline void ext4_set_block_group_nr(struct super_block *sb, char *data, + ext4_group_t group) +{ + struct ext4_super_block *es = (struct ext4_super_block *) data; + + es->s_block_group_nr = cpu_to_le16(group); + if (ext4_has_metadata_csum(sb)) + es->s_checksum = ext4_superblock_csum(sb, es); +} + /* * Update the backup copies of the ext4 metadata. These don't need to be part * of the main resize transaction, because e2fsck will re-write them if there @@ -1158,7 +1168,8 @@ static void update_backups(struct super_ while (group < sbi->s_groups_count) { struct buffer_head *bh; ext4_fsblk_t backup_block; - struct ext4_super_block *es; + int has_super = ext4_bg_has_super(sb, group); + ext4_fsblk_t first_block = ext4_group_first_block_no(sb, group);
/* Out of journal space, and can't get more - abort - so sad */ err = ext4_resize_ensure_credits_batch(handle, 1); @@ -1168,8 +1179,7 @@ static void update_backups(struct super_ if (meta_bg == 0) backup_block = ((ext4_fsblk_t)group) * bpg + blk_off; else - backup_block = (ext4_group_first_block_no(sb, group) + - ext4_bg_has_super(sb, group)); + backup_block = first_block + has_super;
bh = sb_getblk(sb, backup_block); if (unlikely(!bh)) { @@ -1187,10 +1197,8 @@ static void update_backups(struct super_ memcpy(bh->b_data, data, size); if (rest) memset(bh->b_data + size, 0, rest); - es = (struct ext4_super_block *) bh->b_data; - es->s_block_group_nr = cpu_to_le16(group); - if (ext4_has_metadata_csum(sb)) - es->s_checksum = ext4_superblock_csum(sb, es); + if (has_super && (backup_block == first_block)) + ext4_set_block_group_nr(sb, bh->b_data, group); set_buffer_uptodate(bh); unlock_buffer(bh); err = ext4_handle_dirty_metadata(handle, NULL, bh);