From bd63f6b0cd577e94846869db0c86a7b2bee79b26 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Mon, 12 May 2014 10:06:27 -0400 Subject: ext4: find the group descriptors on a 1k-block bigalloc,meta_bg filesystem On a filesystem with a 1k block size, the group descriptors live in block 2, not block 1. If the filesystem has bigalloc,meta_bg set, however, the calculation of the group descriptor table location does not take this into account and returns the wrong block number. Fix the calculation to return the correct value for this case. Signed-off-by: Darrick J. Wong Signed-off-by: "Theodore Ts'o" --- fs/ext4/super.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'fs') diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 1f8cb18..e38dd7d 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2405,6 +2405,16 @@ static ext4_fsblk_t descriptor_loc(struct super_block *sb, if (ext4_bg_has_super(sb, bg)) has_super = 1; + /* + * If we have a meta_bg fs with 1k blocks, group 0's GDT is at + * block 2, not 1. If s_first_data_block == 0 (bigalloc is enabled + * on modern mke2fs or blksize > 1k on older mke2fs) then we must + * compensate. + */ + if (sb->s_blocksize == 1024 && nr == 0 && + le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block) == 0) + has_super++; + return (has_super + ext4_group_first_block_no(sb, bg)); } -- cgit v1.1