[PATCH] add a vfs_permission helper

Most permission() calls have a struct nameidata * available.  This helper
takes that as an argument and thus makes sure we pass it down for lookup
intents and prepares for per-mount read-only support where we need a struct
vfsmount for checking whether a file is writeable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 41feca3..acc73ba 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -676,7 +676,7 @@
 		err = path_lookup(sunname->sun_path, LOOKUP_FOLLOW, &nd);
 		if (err)
 			goto fail;
-		err = permission(nd.dentry->d_inode,MAY_WRITE, &nd);
+		err = vfs_permission(&nd, MAY_WRITE);
 		if (err)
 			goto put_fail;