[PATCH 3.19.y-ckt 92/92] md/raid0: fix restore to sector variable in raid0_make_request

[Philip Müller]

Hi Kamal,

When you apply this one you should also apply followed patch:

>From a81157768a00e8cf8a7b43b5ea5cac931262374f Mon Sep 17 00:00:00 2001
From: Eric Work <work.eric at gmail.com>
Date: Mon, 18 May 2015 23:26:23 -0700
Subject: [PATCH] md/raid0: fix restore to sector variable in
raid0_make_request

See also:

http://git.neil.brown.name/?p=md.git;a=commitdiff;h=a81157768a00e8cf8a7b43b5ea5cac931262374f
https://lkml.org/lkml/2015/5/21/167

kind regards

Philip Müller
---------------------
Manjaro Project-Lead


Am 26.05.2015 um 17:41 schrieb Kamal Mostafa:
> 3.19.8-ckt1 -stable review patch.  If anyone has any objections,
> please let me know.
> 
> ------------------
> 
> From: Eric Work <work.eric at gmail.com>
> 
> commit a81157768a00e8cf8a7b43b5ea5cac931262374f upstream.
> 
> The variable "sector" in "raid0_make_request()" was improperly
> updated by a call to "sector_div()" which modifies its first
> argument in place. Commit 47d68979cc968535cb87f3e5f2e6a3533ea48fbd
> restored this variable after the call for later re-use.
> Unfortunetly the restore was done after the referenced variable
> "bio" was advanced.  This lead to the original value and the
> restored value being different.  Here we move this line to the
> proper place.
> 
> One observed side effect of this bug was discarding a file though 
> unlinking would cause an unrelated file's contents to be
> discarded.
> 
> Signed-off-by: NeilBrown <neilb at suse.de> Fixes: 47d68979cc96
> ("md/raid0: fix bug with chunksize not a power of 2.") URL:
> https://bugzilla.kernel.org/show_bug.cgi?id=98501 Signed-off-by:
> Kamal Mostafa <kamal at canonical.com> --- drivers/md/raid0.c | 4
> +++- 1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c index
> d5c12e5..b974ff2 100644 --- a/drivers/md/raid0.c +++
> b/drivers/md/raid0.c @@ -530,6 +530,9 @@ static void
> raid0_make_request(struct mddev *mddev, struct bio *bio) ? (sector
> & (chunk_sects-1)) : sector_div(sector, chunk_sects));
> 
> +		/* Restore due to sector_div */ +		sector =
> bio->bi_iter.bi_sector; + if (sectors < bio_sectors(bio)) { split =
> bio_split(bio, sectors, GFP_NOIO, fs_bio_set); bio_chain(split,
> bio); @@ -537,7 +540,6 @@ static void raid0_make_request(struct
> mddev *mddev, struct bio *bio) split = bio; }
> 
> -		sector = bio->bi_iter.bi_sector; zone =
> find_zone(mddev->private, &sector); tmp_dev = map_sector(mddev,
> zone, sector, &sector); split->bi_bdev = tmp_dev->bdev;
>