[3.13.y-ckt stable] Patch "rbd: end I/O the entire obj_request on error" has been added to staging queue

[Kamal Mostafa]

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

    rbd: end I/O the entire obj_request on error

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt22.

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-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From ab368fa419d869839967d1683f85873bd4131875 Mon Sep 17 00:00:00 2001
From: Ilya Dryomov <idryomov at gmail.com>
Date: Sat, 25 Apr 2015 15:56:15 +0300
Subject: rbd: end I/O the entire obj_request on error

commit 082a75dad84d79d1c15ea9e50f31cb4bb4fa7fd6 upstream.

When we end I/O struct request with error, we need to pass
obj_request->length as @nr_bytes so that the entire obj_request worth
of bytes is completed.  Otherwise block layer ends up confused and we
trip on

    rbd_assert(more ^ (which == img_request->obj_request_count));

in rbd_img_obj_callback() due to more being true no matter what.  We
already do it in most cases but we are missing some, in particular
those where we don't even get a chance to submit any obj_requests, due
to an early -ENOMEM for example.

A number of obj_request->xferred assignments seem to be redundant but
I haven't touched any of obj_request->xferred stuff to keep this small
and isolated.

Cc: Alex Elder <elder at linaro.org>
Reported-by: Shawn Edwards <lesser.evil at gmail.com>
Reviewed-by: Sage Weil <sage at redhat.com>
Signed-off-by: Ilya Dryomov <idryomov at gmail.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/block/rbd.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 43d562d..873b2d7 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -2103,6 +2103,11 @@ static bool rbd_img_obj_end_request(struct rbd_obj_request *obj_request)
 			result, xferred);
 		if (!img_request->result)
 			img_request->result = result;
+		/*
+		 * Need to end I/O on the entire obj_request worth of
+		 * bytes in case of error.
+		 */
+		xferred = obj_request->length;
 	}

 	/* Image object requests don't own their page array */
--
1.9.1