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From: Jens Axboe <axboe@kernel.dk>
To: Ming Lei <ming.lei@redhat.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>,
	Christoph Hellwig <hch@infradead.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	David Sterba <dsterba@suse.cz>, Huang Ying <ying.huang@intel.com>,
	linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	Theodore Ts'o <tytso@mit.edu>,
	"Darrick J . Wong" <darrick.wong@oracle.com>,
	Coly Li <colyli@suse.de>, Filipe Manana <fdmanana@gmail.com>
Subject: Re: [RESEND PATCH V5 00/33] block: support multipage bvec
Date: Sun, 27 May 2018 19:44:52 -0600	[thread overview]
Message-ID: <cc266632-497c-6849-e291-4f042c8d987a@kernel.dk> (raw)
In-Reply-To: <20180527072332.GA18240@ming.t460p>

On 5/27/18 1:23 AM, Ming Lei wrote:
> On Fri, May 25, 2018 at 10:30:46AM -0600, Jens Axboe wrote:
>> On 5/24/18 10:53 PM, Kent Overstreet wrote:
>>> On Fri, May 25, 2018 at 11:45:48AM +0800, Ming Lei wrote:
>>>> Hi,
>>>>
>>>> This patchset brings multipage bvec into block layer:
>>>
>>> patch series looks sane to me. goddamn that's a lot of renaming.
>>
>> Indeed... I actually objected to some of the segment -> page
>> renaming, but it's still in there. The foo2() temporary functions
>> also concern me, we all know there's nothing more permanent than a
>> temporary fixup.
> 
> Jens, I remember I explained the renaming story to you in lsfmm a bit:
> 
> 1) the current naming of segment is actually wrong, since every segment
> only stores one single-page vector
> 
> 2) the most important part is that once multipage bvec is introduced,
> if the old _segment naming is still kept, it can be very confusing,
> especially no good name is left for the helpers of dealing with real
> segment.

Yes, we discussed exactly this, which is why I'm surprised you went
ahead with the same approach. I told you I don't like tree wide renames,
if they can be avoided. I'd rather suffer some pain wrt page vs segments
naming, and then later do a rename (if it bothers us) once the dust has
settled on the interesting part of the changes.

I'm very well away of our current naming and what it signifies.  With
#1, you are really splitting hairs, imho. Find a decent name for
multiple segment. Chunk?

> For the foo2() temporary change, that is only for avoiding tree-wide
> change in one single tree, with this way, we can change sub-system one
> by one, but if you think it is good to do tree-wide conversion in one
> patch, I am fine to do it in next version.

It's still a painful middle step.

>>> Things are going to get interesting when we start sticking compound
>>> pages in the page cache, there'll be some interesting questions of
>>> semantics to deal with then but I think getting this will only help
>>> w.r.t. plumbing that through and not dealing with 4k pages
>>> unnecessarily - but I think even if we were to decide that merging
>>> in bio_add_page() is not the way to go when the upper layers are
>>> passing compound pages around already, this patch series helps
>>> because regardless at some point everything under
>>> generic_make_request() is going to have to deal with segments that
>>> are more than one page, and this patch series makes that happen. So
>>> incremental progress.
>>>
>>> Jens, any objections to getting this in?
>>
>> I like most of it, but I'd much rather get this way earlier in the
>> series.  We're basically just one week away from the merge window, it
>> needs more simmer and testing time than that. On top of that, it
>> hasn't received much review yet.
>>
>> So as far as I'm concerned, we can kick off the 4.19 block branch
>> with iterated versions of this patchset.
> 
> OK, I will post out again once v4.19 is started.

Sounds good.

-- 
Jens Axboe

  reply	other threads:[~2018-05-28  1:44 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-25  3:45 [RESEND PATCH V5 00/33] block: support multipage bvec Ming Lei
2018-05-25  3:45 ` [RESEND PATCH V5 01/33] block: rename bio_for_each_segment* with bio_for_each_page* Ming Lei
2018-05-25  3:45 ` [RESEND PATCH V5 02/33] block: rename rq_for_each_segment as rq_for_each_page Ming Lei
2018-05-25  3:45 ` [RESEND PATCH V5 03/33] block: rename bio_segments() with bio_pages() Ming Lei
2018-05-25  3:45 ` [RESEND PATCH V5 04/33] block: introduce multipage page bvec helpers Ming Lei
2018-05-25  3:45 ` [RESEND PATCH V5 05/33] block: introduce bio_for_each_segment() Ming Lei
2018-05-25  3:45 ` [RESEND PATCH V5 06/33] block: use bio_for_each_segment() to compute segments count Ming Lei
2018-05-25  3:45 ` [RESEND PATCH V5 07/33] block: use bio_for_each_segment() to map sg Ming Lei
2018-05-25  3:45 ` [RESEND PATCH V5 08/33] block: introduce segment_last_page() Ming Lei
2018-05-25  3:45 ` [RESEND PATCH V5 09/33] fs/buffer.c: use bvec iterator to truncate the bio Ming Lei
2018-05-25  3:45 ` [RESEND PATCH V5 10/33] btrfs: use segment_last_page to get bio's last page Ming Lei
2018-05-25  3:45 ` [RESEND PATCH V5 11/33] block: implement bio_pages_all() via bio_for_each_page_all() Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 12/33] block: introduce bio_segments() Ming Lei
2018-05-25  4:42   ` Kent Overstreet
2018-05-25  3:46 ` [RESEND PATCH V5 13/33] block: introduce rq_for_each_segment() Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 14/33] block: loop: pass segments to iov_iter Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 15/33] block: introduce bio_clone_seg_bioset() Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 16/33] dm: clone bio via bio_clone_seg_bioset Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 17/33] block: bio: introduce bio_for_each_page_all2 and bio_for_each_segment_all Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 18/33] block: deal with dirtying pages for multipage bvec Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 19/33] block: convert to bio_for_each_page_all2() Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 20/33] md/dm/bcache: conver to bio_for_each_page_all2 and bio_for_each_segment Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 21/33] fs: conver to bio_for_each_page_all2 Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 22/33] btrfs: " Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 23/33] ext4: " Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 24/33] f2fs: " Ming Lei
2018-05-28  7:29   ` Chao Yu
2018-05-25  3:46 ` [RESEND PATCH V5 25/33] xfs: " Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 26/33] exofs: " Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 27/33] gfs2: " Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 28/33] block: kill bio_for_each_page_all() Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 29/33] block: rename bio_for_each_page_all2 as bio_for_each_page_all Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 30/33] block: enable multipage bvecs Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 31/33] block: bio: pass segments to bio if bio_add_page() is bypassed Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 32/33] block: always define BIO_MAX_PAGES as 256 Ming Lei
2018-05-25  3:46 ` [RESEND PATCH V5 33/33] block: document usage of bio iterator helpers Ming Lei
2018-05-25 16:16   ` Randy Dunlap
2018-05-25  4:53 ` [RESEND PATCH V5 00/33] block: support multipage bvec Kent Overstreet
2018-05-25 16:30   ` Jens Axboe
2018-05-27  7:23     ` Ming Lei
2018-05-28  1:44       ` Jens Axboe [this message]
2018-05-28  2:30         ` Ming Lei
2018-06-01  8:43           ` Christoph Hellwig
2018-06-01 23:55             ` Ming Lei
2018-06-01  8:35         ` Christoph Hellwig
2018-06-02  3:29           ` Ming Lei
2018-06-01 14:09 ` David Sterba
2018-06-08 12:50   ` Ming Lei

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