Andreas Dilger Wrote: > On Jan 20, 2009 12:30 +0800, Coly Li wrote: >> Ext[234] is sophisticated to have on-disk uuid record. Most file systems >> in the patches (except jfs and reiser3) do not have a persistent uuid, >> a reasonable/feasible solution without media format modification is fsid >> in boot/mount life cycle. That's why huge_encode_dev(sb->s_bdev->bd_dev) >> is used here. For jfs and reiserfs3, is there any use case for >> persistent fsid cross boots ? > > I would say yes, this is worthwhile to do, or the fsid can change between > boots unnecessarily. > If no partitioning happens between boots/mounts, fsid from huge_encode_dev() should be identical. For non-uuid file systems, IMHO huge_encode_dev() method is acceptable. But YES, for jfs and reiserfs3 there is chance to provide persistent fsid cross boots, here are examples, - in fs/jfs/super.c:jfs_statfs(), generate f_fsid by: buf->f_fsid.val[0] = crc32_le(0, sbi->uuid, sizeof(sbi->uuid)/2); buf->f_fsid.val[1] = crc32_le(0, sbi->uuid + sizeof(sbi->uuid)/2, sizeof(sbi->uuid)/2); - in fs/reiserfs/super.c:reiserfs_statfs(), generate f_fsid by: buf->f_fsid.val[0] = (u32)crc32_le(0, rs->s_uuid, sizeof(rs->s_uuid)/2); buf->f_fsid.val[1] = (u32)crc32_le(0, rs->s_uuid + sizeof(rs->s_uuid)/2, sizeof(rs->s_uuid)/2); I will update corresponded patches for the implementation. Thanks for your comments. -- Coly Li SuSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
