[dm-devel] [PATCH v2] block: do not merge two requests with sg gaps if unsupported

[Keith Busch]

On Fri, 6 Feb 2015, Mike Snitzer wrote:
> On Sat, Jan 24 2015 at  5:10P -0500,
> Keith Busch <keith.busch at intel.com> wrote:
>
>> This has request based dm inherit the QUEUE_FLAG_SG_GAPS flags from its
>> underlying block devices' request queues, and does not merge two requests
>> with sg gaps when required. This fixes problems when submitting cloned
>> requests to multipathed devices requiring virtually contiguous buffers.
>>
>> Signed-off-by: Keith Busch <keith.busch at intel.com>
>
> Hi Keith,
>
> I reviewed your patch and cleaned it up a little.  Just some whitespace
> nits and used test_bit().  I also renamed dm-table.c's
> queue_contiguous_sg() to queue_supports_sg_gaps() to follow the pattern
> established by the existing queue_supports_sg_merge().

Thanks Mike! Your modifications look good to me. I try to adapt to the
local lingo, but rarely get it right. :)

> Jens, provided you and Keith agree with my changes, and given that the
> initial request-based DM support for blk-mq will land during the 3.20
> merge: can you please pick this fix up for 3.20?  If you'd prefer to
> just take the block change I'm fine with picking up the DM portion.
>
> Let me know, thanks!
> Mike