[PATCH] knfsd: Fix stale file handle problem with subtree_checking.

A recent commit (7fc90ec93a) moved the
call to nfsd_setuser out of the 'find a dentry for a filehandle' branch
of fh_verify so that it would always be called.

This had the unfortunately side-effect of moving *after* the call to
decode_fh, so the prober fsuid was not set when nfsd_acceptable was called,
the 'permission' check did the wrong thing.

This patch moves the nfsd_setuser call back where it was, and add as call
in the other branch of the if.

Cc: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/nfsd/nfsfh.c

@@ -187,6 +187,11 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
 			goto out;
 		}
 
+		/* Set user creds for this exportpoint */
+		error = nfserrno(nfsd_setuser(rqstp, exp));
+		if (error)
+			goto out;
+
 		/*
 		 * Look up the dentry using the NFS file handle.
 		 */
@@ -241,16 +246,17 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
 		dprintk("nfsd: fh_verify - just checking\n");
 		dentry = fhp->fh_dentry;
 		exp = fhp->fh_export;
+		/* Set user creds for this exportpoint; necessary even
+		 * in the "just checking" case because this may be a
+		 * filehandle that was created by fh_compose, and that
+		 * is about to be used in another nfsv4 compound
+		 * operation */
+		error = nfserrno(nfsd_setuser(rqstp, exp));
+		if (error)
+			goto out;
 	}
 	cache_get(&exp->h);
 
-	/* Set user creds for this exportpoint; necessary even in the "just
-	 * checking" case because this may be a filehandle that was created by
-	 * fh_compose, and that is about to be used in another nfsv4 compound
-	 * operation */
-	error = nfserrno(nfsd_setuser(rqstp, exp));
-	if (error)
-		goto out;
 
 	error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
 	if (error)