Re: [dm-devel] [PATCH 0/3] fix direct io errors on dm-crypt

[Mikulas Patocka <mpatocka@redhat.com>]

Hi

The patchset seems OK - but dm-integrity also has a limitation that the 
bio vectors must be aligned on logical block size.

dm-writecache and dm-verity seem to handle unaligned bioset, but you 
should check them anyway.

I'm not sure about dm-log-writes.

Mikulas


On Thu, 3 Nov 2022, Keith Busch wrote:

> From: Keith Busch <kbusch@kernel.org>
> 
> The 6.0 kernel made some changes to the direct io interface to allow
> offsets in user addresses. This based on the hardware's capabilities
> reported in the request_queue's dma_alignment attribute.
> 
> dm-crypt requires direct io be aligned to the block size. Since it was
> only ever using the default 511 dma mask, this requirement may fail if
> formatted to something larger, like 4k, which will result in unexpected
> behavior with direct-io.
> 
> There are two parts to fixing this:
> 
>   First, the attribute needs to be moved to the queue_limit so that it
>   can properly stack with device mappers.
> 
>   Second, dm-crypt provides its minimum required limit to match the
>   logical block size.
> 
> Keith Busch (3):
>   block: make dma_alignment a stacking queue_limit
>   dm-crypt: provide dma_alignment limit in io_hints
>   block: make blk_set_default_limits() private
> 
>  block/blk-core.c       |  1 -
>  block/blk-settings.c   |  9 +++++----
>  block/blk.h            |  1 +
>  drivers/md/dm-crypt.c  |  1 +
>  include/linux/blkdev.h | 16 ++++++++--------
>  5 files changed, 15 insertions(+), 13 deletions(-)
> 
> -- 
> 2.30.2
> 
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