From: Andreas Gruenbacher <agruen@suse.de>
Subject: Distinguish between connected and disconnected paths in d_path()

Change d_path() so that it will never return a path starting with '/' if
the path doesn't lead up to the chroot directory. Also ensure that the
path returned never is the empty string: this would only occur with a lazily unmounted file system; return "." in that case instead.

Signed-off-by: Andreas Gruenbacher <agruen@suse.de>

---
 fs/dcache.c    |   18 ++++--------------
 fs/namespace.c |    3 ---
 2 files changed, 4 insertions(+), 17 deletions(-)

--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1829,8 +1829,11 @@ global_root:
 			buffer++;
 			buflen++;
 		}
-		if (is_slash)
+		if (is_slash) {
+			if (*buffer == '\0')
+				*--buffer = '.';
 			goto out;
+		}
 	}
 	if (buflen < namelen)
 		goto Elong;
@@ -1843,18 +1846,6 @@ Elong:
 	goto out;
 }
 
-static char *__connect_d_path(char *path, char *buffer)
-{
-	if (!IS_ERR(path) && *path != '/') {
-		/* Pretend that disconnected paths are hanging off the root. */
-		if (path == buffer)
-			path = ERR_PTR(-ENAMETOOLONG);
-		else
-			*--path = '/';
-	}
-	return path;
-}
-
 /* write full pathname into buffer and return start of pathname */
 char *d_path(struct dentry *dentry, struct vfsmount *vfsmnt, char *buf,
 	     int buflen)
@@ -1868,7 +1859,6 @@ char *d_path(struct dentry *dentry, stru
 	root = dget(current->fs->root);
 	read_unlock(&current->fs->lock);
 	res = __d_path(dentry, vfsmnt, root, rootmnt, buf, buflen, 0);
-	res = __connect_d_path(res, buf);
 	dput(root);
 	mntput(rootmnt);
 	return res;
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1917,9 +1917,6 @@ char *d_namespace_path(struct dentry *de
 	res = __d_path(dentry, vfsmnt, root, nsrootmnt, buf, buflen, 1);
 	dput(root);
 	mntput(nsrootmnt);
-	/* Prevent empty path for lazily unmounted filesystems. */
-	if (!IS_ERR(res) && *res == '\0')
-		*--res = '.';
 	return res;
 }
 EXPORT_SYMBOL(d_namespace_path);