[ 3.8.y.z extended stable ] Patch "cifs: don't instantiate new dentries in readdir for inodes that need" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    cifs: don't instantiate new dentries in readdir for inodes that need

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.7.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From ce61ff9871d98d718e9e9206fd3d8becc9591512 Mon Sep 17 00:00:00 2001
From: Jeff Layton <jlayton at redhat.com>
Date: Wed, 7 Aug 2013 10:29:08 -0400
Subject: cifs: don't instantiate new dentries in readdir for inodes that need
 to be revalidated immediately

commit 757c4f6260febff982276818bb946df89c1105aa upstream.

David reported that commit c2b93e06 (cifs: only set ops for inodes in
I_NEW state) caused a regression with mfsymlinks. Prior to that patch,
if a mfsymlink dentry was instantiated at readdir time, the inode would
get a new set of ops when it was revalidated. After that patch, this
did not occur.

This patch addresses this by simply skipping instantiating dentries in
the readdir codepath when we know that they will need to be immediately
revalidated. The next attempt to use that dentry will cause a new lookup
to occur (which is basically what we want to happen anyway).

Cc: "Stefan (metze) Metzmacher" <metze at samba.org>
Cc: Sachin Prabhu <sprabhu at redhat.com>
Reported-and-Tested-by: David McBride <dwm37 at cam.ac.uk>
Signed-off-by: Jeff Layton <jlayton at redhat.com>
Signed-off-by: Steve French <smfrench at gmail.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 fs/cifs/readdir.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index cdd6ff4..5e636a8 100644
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -113,6 +113,14 @@ cifs_prime_dcache(struct dentry *parent, struct qstr *name,
 			return;
 	}

+	/*
+	 * If we know that the inode will need to be revalidated immediately,
+	 * then don't create a new dentry for it. We'll end up doing an on
+	 * the wire call either way and this spares us an invalidation.
+	 */
+	if (fattr->cf_flags & CIFS_FATTR_NEED_REVAL)
+		return;
+
 	dentry = d_alloc(parent, name);
 	if (!dentry)
 		return;
--
1.8.1.2