On 2011-09-14, at 1:31 PM, Darrick J. Wong wrote: > On Wed, Sep 14, 2011 at 01:02:59PM -0400, Ted Ts'o wrote: >> On Wed, Aug 31, 2011 at 05:36:22PM -0700, Darrick J. Wong wrote: >>> diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h >>> index 1f08673..367bfdf 100644 >>> --- a/lib/ext2fs/ext2_fs.h >>> +++ b/lib/ext2fs/ext2_fs.h >>> @@ -169,7 +169,8 @@ struct ext4_group_desc >>> __u16 bg_free_inodes_count_hi;/* Free inodes count MSB */ >>> __u16 bg_used_dirs_count_hi; /* Directories count MSB */ >>> __u16 bg_itable_unused_hi; /* Unused inodes count MSB */ >>> - __u32 bg_reserved2[3]; >>> + __u32 bg_inode_bitmap_csum; /* crc32c(uuid+group+ibitmap) */ >>> + __u32 bg_reserved2[2]; >>> }; >> >> >> One of the reasons why I like to coalesce the patches to the data >> structures into their own separate commit, is it's hard when I'm >> reviewing individual patches in a mail reader what's going on from a >> big picture spective. (Heck, even just *finding* the patches that >> modify the on-disk format is hard....) >> >> But as near as I can tell, your patch series only uses one of the >> 32-bit fields in bg_reserved. Is there a good reason why >> bg_inode_bitmap_csum can't also used one of the two fields in >> bg_reserved? That way we get two 32-bit checksums for both struct >> ext2_group_desc and struct ext4_group_desc. Is there a third 32-bit >> per-block group checksum I'm forgetting about? > > No, but I was under the impression that Amir was using one of bg_reserved for > snapshots. If that's not true, I'll move both bitmap checksums to bg_reserved. He was, AND the first bg_reserved2 field as well, which the above use would conflict with. See my other patch. Cheers, Andreas -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
