[3.11.y.z extended stable] Patch "bio-integrity: Fix bio_integrity_verify segment start bug" has been added to staging queue

[Luis Henriques]

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

    bio-integrity: Fix bio_integrity_verify segment start bug

to the linux-3.11.y-queue branch of the 3.11.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-3.11.y-queue

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

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 4cef7f69f4ca9ef8ad23ff27066bdd43f769e487 Mon Sep 17 00:00:00 2001
From: Nicholas Bellinger <nab at linux-iscsi.org>
Date: Tue, 21 Jan 2014 20:32:05 -0800
Subject: bio-integrity: Fix bio_integrity_verify segment start bug

commit 5837c80e870bc3b12ac6a98cdc9ce7a9522a8fb6 upstream.

This patch addresses a bug in bio_integrity_verify() code that has
been causing DIF READ verify operations to be silently skipped.

The issue is that bio->bi_idx will have been incremented within
bio_advance() code in the normal blk_update_request() ->
req_bio_endio() completion path, and bio_integrity_verify() is
using bio_for_each_segment() which starts the bio segment walk
at the current bio->bi_idx.

So instead use bio_for_each_segment_all() to always start the bio
segment walk from zero, regardless of the current bio->bi_idx
value after bio_advance() has been called.

Cc: Martin K. Petersen <martin.petersen at oracle.com>
Cc: Jens Axboe <axboe at kernel.dk>
Cc: Christoph Hellwig <hch at lst.de>
Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
Signed-off-by: Jens Axboe <axboe at kernel.dk>
[ luis: backported to 3.11: used Nicholas's backport to v3.10.y+ ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 fs/bio-integrity.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/bio-integrity.c b/fs/bio-integrity.c
index 8dccf73..433c3b8 100644
--- a/fs/bio-integrity.c
+++ b/fs/bio-integrity.c
@@ -458,7 +458,7 @@ static int bio_integrity_verify(struct bio *bio)
 	bix.disk_name = bio->bi_bdev->bd_disk->disk_name;
 	bix.sector_size = bi->sector_size;

-	bio_for_each_segment(bv, bio, i) {
+	bio_for_each_segment_all(bv, bio, i) {
 		void *kaddr = kmap_atomic(bv->bv_page);
 		bix.data_buf = kaddr + bv->bv_offset;
 		bix.data_size = bv->bv_len;
--
1.9.0