[PATCH v4 0/8] block: prepare for multipage bvecs

[PATCH v4 0/8] block: prepare for multipage bvecs

[Ming Lei]

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 & BIO_MAX_SIZE, 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.

xfstests(-a auto) have been run over ext4/xfs and no regression found
by this patchset.


V4:
	- make xfstests cover xfs
	- rebase on for-next of block tree
V3:
	- include kenrel.h & bug.h in bvec.h for fix comiling failure on arm
	as reported by 0day ktest
	- build test on arm & arm64

V2:
	- rename bvec_iter.h as bvec.h
	- always include bvec.h into blk_types.h as suggested by Christoph

V1:
	- don't move BIO_MAX_* to bvec_iter.h as pointed out by Christoph
	- run xfstests against v4.6-rc1-next-20160329
	- add Reviewed-by
	- for 1,4 and 5, Reviewd-by not added, Christoph still expressed
        'this looks fine to me.'

Ming Lei (10):
  block: move bvec iterator into include/linux/bvec.h
  block: move two bvec structure into bvec.h
  block: mark 1st parameter of bvec_iter_advance as const
  iov_iter: use bvec iterator to implement iterate_bvec()
  fs: xfs: replace BIO_MAX_SECTORS with BIO_MAX_PAGES
  block: bio: remove BIO_MAX_SECTORS
  block: drbd: avoid to use BIO_MAX_SIZE
  block: bio: remove BIO_MAX_SIZE
  block: make sure big bio is splitted into at most 256 bvecs
  block: allow to merge bios if splitting because of big bvecs num

 block/blk-merge.c             | 35 ++++++++++++++--
 drivers/block/drbd/drbd_int.h |  4 +-
 fs/xfs/xfs_buf.c              |  4 +-
 include/linux/bio.h           | 52 -----------------------
 include/linux/blk_types.h     | 22 +---------
 include/linux/bvec.h          | 96 +++++++++++++++++++++++++++++++++++++++++++
 lib/iov_iter.c                | 30 +++++---------
 7 files changed, 142 insertions(+), 101 deletions(-)
 create mode 100644 include/linux/bvec.h

-- 
1.9.1

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

[PATCH v4 5/8] fs: xfs: replace BIO_MAX_SECTORS with BIO_MAX_PAGES

[Ming Lei]

BIO_MAX_PAGES is used as maximum count of bvecs, so
replace BIO_MAX_SECTORS with BIO_MAX_PAGES since
BIO_MAX_SECTORS is to be removed.

Signed-off-by: Ming Lei <ming.lei@canonical.com>
---
 fs/xfs/xfs_buf.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 9a2191b..b9ecb2d 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1161,9 +1161,7 @@ xfs_buf_ioapply_map(
 
 next_chunk:
 	atomic_inc(&bp->b_io_remaining);
-	nr_pages = BIO_MAX_SECTORS >> (PAGE_SHIFT - BBSHIFT);
-	if (nr_pages > total_nr_pages)
-		nr_pages = total_nr_pages;
+	nr_pages = min(total_nr_pages, BIO_MAX_PAGES);
 
 	bio = bio_alloc(GFP_NOIO, nr_pages);
 	bio->bi_bdev = bp->b_target->bt_bdev;
-- 
1.9.1

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

Re: [PATCH v4 0/8] block: prepare for multipage bvecs

[Jens Axboe]

On 04/14/2016 05:46 AM, Ming Lei 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 & BIO_MAX_SIZE, 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.
>
> xfstests(-a auto) have been run over ext4/xfs and no regression found
> by this patchset.

We've had too many disasters in the block layer the last few series, I'm 
making the 4.7 round a nice and small one. I don't mind taking prep 
patches for the multipage bvecs, if they are simple and clean, but 
that's about the extent of it.

Just a heads up.

-- 
Jens Axboe

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

Re: [PATCH v4 0/8] block: prepare for multipage bvecs

[Ming Lei]

On Thu, Apr 14, 2016 at 10:11 PM, Jens Axboe <axboe@kernel.dk> wrote:
> On 04/14/2016 05:46 AM, Ming Lei 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 & BIO_MAX_SIZE, 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.
>>
>> xfstests(-a auto) have been run over ext4/xfs and no regression found
>> by this patchset.
>
>
> We've had too many disasters in the block layer the last few series, I'm
> making the 4.7 round a nice and small one. I don't mind taking prep patches
> for the multipage bvecs, if they are simple and clean, but that's about the
> extent of it.
>
> Just a heads up.

Jens, thanks for your response, and understood your concerns.

Please hold on this patchset, and I will check it further and make it
better.

Thanks,

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs