Re: [PATCH v7] NVMe: conversion to blk-mq

Keith Busch
2014-06-10T21:11:56Z

On Tue, 10 Jun 2014, Jens Axboe wrote:
> On 06/10/2014 01:29 PM, Keith Busch wrote:
>> I have two devices, one formatted 4k, the other 512. The 4k is used as
>> the TEST_DEV and 512 is used as SCRATCH_DEV. I'm always hitting a BUG when
>> unmounting the scratch dev in xfstests generic/068. The bug looks like
>> nvme was trying to use an SGL that doesn't map correctly to a PRP.
>
> I'm guessing it's some of the coalescing settings, since the driver is
> now using the generic block rq mapping.

Ok, sounds right. I mentioned in a way earlier review it doesn't look
like a request that doesn't conform to a PRP list would get split anymore,
and this test seems to confirm that.

Can we create something that will allow a driver to add DMA constraints to
a request queue with the rules of a PRP list?