[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>

1 files changed, 16 insertions, 3 deletions

diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
index 6555c50d9006..0c24b9e24fe8 100644
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -153,6 +153,7 @@ encode_fattr(struct svc_rqst *rqstp, __be32 *p, struct svc_fh *fhp,
         struct dentry   *dentry = fhp->fh_dentry;
         int type;
         struct timespec time;
+        u32 f;
 
         type = (stat->mode & S_IFMT);
 
@@ -173,10 +174,22 @@ encode_fattr(struct svc_rqst *rqstp, __be32 *p, struct svc_fh *fhp,
         else
                 *p++ = htonl(0xffffffff);
         *p++ = htonl((u32) stat->blocks);
-        if (is_fsid(fhp, rqstp->rq_reffh))
-                *p++ = htonl((u32) fhp->fh_export->ex_fsid);
-        else
+        switch (fsid_source(fhp)) {
+        default:
+        case FSIDSOURCE_DEV:
                 *p++ = htonl(new_encode_dev(stat->dev));
+                break;
+        case FSIDSOURCE_FSID:
+                *p++ = htonl((u32) fhp->fh_export->ex_fsid);
+                break;
+        case FSIDSOURCE_UUID:
+                f = ((u32*)fhp->fh_export->ex_uuid)[0];
+                f ^= ((u32*)fhp->fh_export->ex_uuid)[1];
+                f ^= ((u32*)fhp->fh_export->ex_uuid)[2];
+                f ^= ((u32*)fhp->fh_export->ex_uuid)[3];
+                *p++ = htonl(f);
+                break;
+        }
         *p++ = htonl((u32) stat->ino);
         *p++ = htonl((u32) stat->atime.tv_sec);
         *p++ = htonl(stat->atime.tv_nsec ? stat->atime.tv_nsec / 1000 : 0);