Re: [PATCH v6 0/8] block: prepare for multipage bvecs

[Ming Lei]

On Tue, May 31, 2016 at 11:53 PM, Mike Snitzer <snitzer@xxxxxxxxxx> wrote:
> On Mon, May 30 2016 at  9:34am -0400,
> Ming Lei <ming.lei@xxxxxxxxxxxxx> wrote:
>
>>
>> Hi,
>>
>> Interests[1] have been shown in multipage bvecs, so this patchset
>> try to prepare for the support and do two things:
>>
>> 1) the 1st 4 patches use bvec iterator to implement iterate_bvec(),
>> then we can drop the non-standard way for iterating bvec, which
>> can be thought as a good cleanup for lib/iov_iter.c
>>
>> 2) remove BIO_MAX_SECTORS and makre BIO_MAX_SIZE as obsolete, and
>> now there is only one user for each. Once multipage bvecs is introduced,
>> one bio may hold lots of sectors, and we should always use sort of
>> BIO_MAX_VECS which should be introduced in future and is similiar
>> with current BIO_MAX_PAGES.
>>
>> The only functional change is iterate_bvec():lib/iov_iter.c
>>
>> xfstests(-a auto) over loop aio is run for ext4/xfs to verify
>> the change and no regression found with this patchset.
>>
>> V6:
>>       - rebased on v4.7-rc1
>>       - add reviewed-by tag
>>       - mark BIO_MAX_SIZE as obsolete instead of removing because
>>       dm-tree adds one usage now
>
> Not sure what you're referring to here with "dm-tree" (since "dm-tree"
> doesn't exist).  But only direct user of "BIO_MAX_SIZE" in DM appears to

Looks it is from crypto tree:

   git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6

> be dm-crypt.c.  Maybe you've identified some indirect use of
> BIO_MAX_SIZE?

I mean the recently introduced BIO_MAX_SIZE in -next tree:

https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/drivers/md/dm-crypt.c?id=4ed89c97b0706477b822ea2182827640c0cec486

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