Re: FAILED: patch "[PATCH] md/raid0: avoid RAID0 data corruption due to layout" failed to apply to 5.3-stable tree

[Sasha Levin <sashal@kernel.org>]

On Thu, Oct 03, 2019 at 09:53:35AM +0200, gregkh@linuxfoundation.org wrote:
>
>The patch below does not apply to the 5.3-stable tree.
>If someone wants it applied there, or to any other stable or longterm
>tree, then please email the backport, including the original git commit
>id to <stable@vger.kernel.org>.
>
>thanks,
>
>greg k-h
>
>------------------ original commit in Linus's tree ------------------
>
>From c84a1372df929033cb1a0441fb57bd3932f39ac9 Mon Sep 17 00:00:00 2001
>From: NeilBrown <neilb@suse.de>
>Date: Mon, 9 Sep 2019 16:30:02 +1000
>Subject: [PATCH] md/raid0: avoid RAID0 data corruption due to layout
> confusion.
>
>If the drives in a RAID0 are not all the same size, the array is
>divided into zones.
>The first zone covers all drives, to the size of the smallest.
>The second zone covers all drives larger than the smallest, up to
>the size of the second smallest - etc.
>
>A change in Linux 3.14 unintentionally changed the layout for the
>second and subsequent zones.  All the correct data is still stored, but
>each chunk may be assigned to a different device than in pre-3.14 kernels.
>This can lead to data corruption.
>
>It is not possible to determine what layout to use - it depends which
>kernel the data was written by.
>So we add a module parameter to allow the old (0) or new (1) layout to be
>specified, and refused to assemble an affected array if that parameter is
>not set.
>
>Fixes: 20d0189b1012 ("block: Introduce new bio_split()")
>cc: stable@vger.kernel.org (3.14+)
>Acked-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
>Signed-off-by: NeilBrown <neilb@suse.de>
>Signed-off-by: Song Liu <songliubraving@fb.com>

Had to adjust context slightly due to missing 62f7b1989c02f ("md
raid0/linear: Mark array as 'broken' and fail BIOs if a member is
gone)" in 5.3-4.14.

On 4.9 and 4.4 we need a more complex backport which I didn't attempt
due to missing be306c2989804 ("md: define mddev flags, recovery flags
and r1bio state bits using enums") and a few fixes of that.

Queued up for 5.3-4.14.

--
Thanks,
Sasha