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

[Jens Axboe]

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. What is the point of this?!

> bio_{enable,disable}_inline_vecs are not expected to be widely used so
> they were exported using EXPORT_SYMBOL_GPL.

Never export anything that doesn't have an in-kernel modular user.

> This patch avoids the need for the following VM accounting fix for
> discards: http://lkml.org/lkml/2010/6/23/361
> NOTE: Jens, you said you applied Tao Ma's fix but I cannot see it in
> your linux-2.6-block's for-next or for-2.6.36... as such I didn't revert
> it in this patch.

It's in the for-linus branch, that is stuff headed for the current
kernel.

-- 
Jens Axboe