Re: [PATCH 2/2] block: defer the use of inline biovecs for discard requests

From: Jens Axboe
Date: Mon Jun 28 2010 - 08:41:35 EST

On 2010-06-28 14:37, Mike Snitzer wrote:
> On Mon, Jun 28 2010 at 8:34am -0400,
> Jens Axboe <axboe@xxxxxxxxx> wrote:
>> On 2010-06-26 21:56, Mike Snitzer wrote:
>>> Don't alloc discard bio with a biovec in blkdev_issue_discard. Doing so
>>> means bio_has_data() will not be true until the SCSI layer adds the
>>> payload to the discard request via blk_add_request_payload.
>> Sorry, this looks horrible.
> Your judgment isn't giving me much to work with... not sure where I go
> with "horrible".

The horrible part is working around that issue by fiddling with the
assignment of the internal vec. THAT looks like a horrible solution
to that problem.

How about just adding a check to bio_has_data() for non-zero

Jens Axboe

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