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ext4: fix corruption when online resizing a 1K bigalloc fs

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When a backup superblock is updated in update_backups(), the primary
superblock's offset in the group (that is, sbi->s_sbh->b_blocknr) is used
as the backup superblock's offset in its group. However, when the block
size is 1K and bigalloc is enabled, the two offsets are not equal. This
causes the backup group descriptors to be overwritten by the superblock
in update_backups(). Moreover, if meta_bg is enabled, the file system will
be corrupted because this feature uses backup group descriptors.

To solve this issue, we use a more accurate ext4_group_first_block_no() as
the offset of the backup superblock in its group.

Fixes: d77147ff44 ("ext4: add support for online resizing with bigalloc")
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/20221117040341.1380702-4-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Baokun Li 2022-11-17 12:03:41 +08:00 committed by Theodore Ts'o
parent 8f49ec603a
commit 0aeaa2559d
1 changed files with 3 additions and 3 deletions
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6
fs/ext4/resize.c
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@ -1604,8 +1604,8 @@ exit_journal:
int meta_bg = ext4_has_feature_meta_bg(sb);
sector_t old_gdb = 0;
update_backups(sb, sbi->s_sbh->b_blocknr, (char *)es,
sizeof(struct ext4_super_block), 0);
update_backups(sb, ext4_group_first_block_no(sb, 0),
(char *)es, sizeof(struct ext4_super_block), 0);
for (; gdb_num <= gdb_num_end; gdb_num++) {
struct buffer_head *gdb_bh;
@ -1816,7 +1816,7 @@ errout:
if (test_opt(sb, DEBUG))
printk(KERN_DEBUG "EXT4-fs: extended group to %llu "
"blocks\n", ext4_blocks_count(es));
update_backups(sb, EXT4_SB(sb)->s_sbh->b_blocknr,
update_backups(sb, ext4_group_first_block_no(sb, 0),
(char *)es, sizeof(struct ext4_super_block), 0);
}
return err;