nfsd: open-code special directory-hardlink check

We allow the fh_verify caller to specify that any object *except* those
of a given type is allowed, by passing a negative type.  But only one
caller actually uses it.  Open-code that check in the one caller.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfsfh.c

@@ -61,7 +61,6 @@ static int nfsd_acceptable(void *expv, struct dentry *dentry)
 static inline __be32
 nfsd_mode_check(struct svc_rqst *rqstp, umode_t mode, int type)
 {
-	/* Type can be negative when creating hardlinks - not to a dir */
 	if (type > 0 && (mode & S_IFMT) != type) {
 		if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
 			return nfserr_symlink;
@@ -72,14 +71,6 @@ nfsd_mode_check(struct svc_rqst *rqstp, umode_t mode, int type)
 		else
 			return nfserr_inval;
 	}
-	if (type < 0 && (mode & S_IFMT) == -type) {
-		if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK)
-			return nfserr_symlink;
-		else if (type == -S_IFDIR)
-			return nfserr_isdir;
-		else
-			return nfserr_notdir;
-	}
 	return 0;
 }
 

fs/nfsd/vfs.c

@@ -1632,10 +1632,12 @@ nfsd_link(struct svc_rqst *rqstp, struct svc_fh *ffhp,
 	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_CREATE);
 	if (err)
 		goto out;
-	err = fh_verify(rqstp, tfhp, -S_IFDIR, NFSD_MAY_NOP);
+	err = fh_verify(rqstp, tfhp, 0, NFSD_MAY_NOP);
 	if (err)
 		goto out;
-
+	err = nfserr_isdir;
+	if (S_ISDIR(tfhp->fh_dentry->d_inode->i_mode))
+		goto out;
 	err = nfserr_perm;
 	if (!len)
 		goto out;