nfsd: allow exports of symlinks

We want to allow exports of symlinks, to allow mountd to communicate to
the kernel which symlinks lead to exports, and hence which symlinks need
to be visible on the pseudofilesystem.
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>

fs/nfsd/export.c

@@ -358,10 +358,12 @@ static struct svc_export *svc_export_lookup(struct svc_export *);
 static int check_export(struct inode *inode, int flags, unsigned char *uuid)
 {
 
-	/* We currently export only dirs and regular files.
-	 * This is what umountd does.
+	/*
+	 * We currently export only dirs, regular files, and (for v4
+	 * pseudoroot) symlinks.
 	 */
 	if (!S_ISDIR(inode->i_mode) &&
+	    !S_ISLNK(inode->i_mode) &&
 	    !S_ISREG(inode->i_mode))
 		return -ENOTDIR;