[3.13.y.z extended stable] Patch "CIFS: Fix async reading on reconnects" 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: Fix async reading on reconnects

to the linux-3.13.y-queue branch of the 3.13.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-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.7.

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

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 9fc9720f1f1ada80a4d6929773517401cc98eb5b Mon Sep 17 00:00:00 2001
From: Pavel Shilovsky <pshilovsky at samba.org>
Date: Fri, 27 Jun 2014 10:33:11 +0400
Subject: CIFS: Fix async reading on reconnects

commit 038bc961c31b070269ecd07349a7ee2e839d4fec upstream.

If we get into read_into_pages() from cifs_readv_receive() and then
loose a network, we issue cifs_reconnect that moves all mids to
a private list and issue their callbacks. The callback of the async
read request sets a mid to retry, frees it and wakes up a process
that waits on the rdata completion.

After the connection is established we return from read_into_pages()
with a short read, use the mid that was freed before and try to read
the remaining data from the a newly created socket. Both actions are
not what we want to do. In reconnect cases (-EAGAIN) we should not
mask off the error with a short read but should return the error
code instead.

Acked-by: Jeff Layton <jlayton at samba.org>
Signed-off-by: Pavel Shilovsky <pshilovsky at samba.org>
Signed-off-by: Steve French <smfrench at gmail.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 fs/cifs/file.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 4911dc8..dd4aaca 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2847,7 +2847,7 @@ cifs_uncached_read_into_pages(struct TCP_Server_Info *server,
 		total_read += result;
 	}

-	return total_read > 0 ? total_read : result;
+	return total_read > 0 && result != -EAGAIN ? total_read : result;
 }

 static ssize_t
@@ -3270,7 +3270,7 @@ cifs_readpages_read_into_pages(struct TCP_Server_Info *server,
 		total_read += result;
 	}

-	return total_read > 0 ? total_read : result;
+	return total_read > 0 && result != -EAGAIN ? total_read : result;
 }

 static int cifs_readpages(struct file *file, struct address_space *mapping,
--
1.9.1