[PATCH] knfsd: add some new fsid types

Add support for using a filesystem UUID to identify and export point in the
filehandle.

For NFSv2, this UUID is xor-ed down to 4 or 8 bytes so that it doesn't take up
too much room.  For NFSv3+, we use the full 16 bytes, and possibly also a
64bit inode number for exports beneath the root of a filesystem.

When generating an fsid to return in 'stat' information, use the UUID (hashed
down to size) if it is available and a small 'fsid' was not specifically
provided.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 18aa944..0efba55 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -1563,14 +1563,20 @@
 		if (exp->ex_fslocs.migrated) {
 			WRITE64(NFS4_REFERRAL_FSID_MAJOR);
 			WRITE64(NFS4_REFERRAL_FSID_MINOR);
-		} else if (is_fsid(fhp, rqstp->rq_reffh)) {
+		} else switch(fsid_source(fhp)) {
+		case FSIDSOURCE_FSID:
 			WRITE64((u64)exp->ex_fsid);
 			WRITE64((u64)0);
-		} else {
+			break;
+		case FSIDSOURCE_DEV:
 			WRITE32(0);
 			WRITE32(MAJOR(stat.dev));
 			WRITE32(0);
 			WRITE32(MINOR(stat.dev));
+			break;
+		case FSIDSOURCE_UUID:
+			WRITEMEM(exp->ex_uuid, 16);
+			break;
 		}
 	}
 	if (bmval0 & FATTR4_WORD0_UNIQUE_HANDLES) {