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Commit a4c3c1d5 authored by Baokun Li's avatar Baokun Li Committed by Greg Kroah-Hartman
Browse files

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



commit 0aeaa2559d6d53358fca3e3fce73807367adca74 upstream.

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: d77147ff ("ext4: add support for online resizing with bigalloc")
Signed-off-by: default avatarBaokun Li <libaokun1@huawei.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20221117040341.1380702-4-libaokun1@huawei.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6f4200ec

fs/ext4/resize.c

+3 −3
Original line number Diff line number Diff line
@@ -1567,8 +1567,8 @@ static int ext4_flex_group_add(struct super_block *sb, 
		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;
@@ -1775,7 +1775,7 @@ static int ext4_group_extend_no_check(struct super_block *sb, 
		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;