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Message-ID: <20131220001541.GA10189@birch.djwong.org> Date: Thu, 19 Dec 2013 16:15:42 -0800 From: "Darrick J. Wong" <darrick.wong@...cle.com> To: "Theodore Ts'o" <tytso@....edu> Cc: linux-ext4 <linux-ext4@...r.kernel.org> Subject: [PATCH] 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 <darrick.wong@...cle.com> --- fs/ext4/super.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 7f52a54..d968c64 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2420,6 +2420,16 @@ 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)); } -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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