Messages in this thread | | | Date | Wed, 7 Dec 2005 05:40:43 -0700 | From | Andreas Dilger <> | Subject | Re: [PATCH] ext3: return FSID for statvfs |
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On Dec 06, 2005 22:23 +0200, Pekka Enberg wrote: > This patch changes ext3_statfs() to return a FSID based on least significant > 64-bits of the 128-bit filesystem UUID. This patch is a partial fix for > Bugzilla Bug <http://bugzilla.kernel.org/show_bug.cgi?id=136>.
The bug mentions some reasons why this patch is sub-optimal - namely that the beginning of the UUID has common fields in it. It may make more sense to e.g. XOR the first 2 * u32 with the last 2 * u32 to reduce the chance of an FSID collision.
Also, there is a tiny memory of a security issue with exposing the FSID to applications (something to do with NFS and guessing filehandles or similar). I have no idea if that is even relevant any longer, but thought I'd mention it.
> @@ -2340,6 +2340,8 @@ static int ext3_statfs (struct super_blo > buf->f_files = le32_to_cpu(es->s_inodes_count); > buf->f_ffree = ext3_count_free_inodes (sb); > buf->f_namelen = EXT3_NAME_LEN; > + buf->f_fsid.val[0] = le32_to_cpup((void *)es->s_uuid); > + buf->f_fsid.val[1] = le32_to_cpup((void *)es->s_uuid + sizeof(u32)); > return 0; > } >
Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc.
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