[PATCH v5 0/8] block: prepare for multipage bvecs

[PATCH v5 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.

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.

Jens, I am confidant this time, so please give it a go if no one
objects. I appreciate someone(AI? or anyone) can give a review on
the patch 4/8 about iterate_bvec() change.

V5:
	- use bvec's iterator to figure new base vec address and
	update 'skip' correctly
	- run xfstests(-a auto) on loop aio/dio for verifying
	the change in iterate_bvec(), and no regression reported
	- use stree-ng to trigger heavy swap over swapfile to verify
	change in iterate_bvec() too, looks everything is fine
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 (8):
  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

 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                | 45 +++++++-------------
 6 files changed, 115 insertions(+), 108 deletions(-)
 create mode 100644 include/linux/bvec.h

-- 
1.9.1

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[PATCH v5 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

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Re: [PATCH v5 5/8] fs: xfs: replace BIO_MAX_SECTORS with BIO_MAX_PAGES

[Christoph Hellwig]

On Mon, Apr 18, 2016 at 05:29:54AM +0800, Ming Lei wrote:
> 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>

Looks fine,

Reviewed-by: Christoph Hellwig <hch@lst.de>

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Re: [PATCH v5 0/8] block: prepare for multipage bvecs

[Ming Lei]

On Mon, Apr 18, 2016 at 5:29 AM, Ming Lei <ming.lei@canonical.com> 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.
>
> 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.
>
> Jens, I am confidant this time, so please give it a go if no one
> objects. I appreciate someone(AI? or anyone) can give a review on
> the patch 4/8 about iterate_bvec() change.
>
> V5:
>         - use bvec's iterator to figure new base vec address and
>         update 'skip' correctly
>         - run xfstests(-a auto) on loop aio/dio for verifying
>         the change in iterate_bvec(), and no regression reported
>         - use stree-ng to trigger heavy swap over swapfile to verify
>         change in iterate_bvec() too, looks everything is fine

Hi Jens,

Any possibility to make v5 into v4.7 so that we can move on about
multipage bvecs?

BTW, even though not considering mp bvecs, this patchset is still a
good cleanup.

thanks,
Ming

> 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 (8):
>   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
>
>  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                | 45 +++++++-------------
>  6 files changed, 115 insertions(+), 108 deletions(-)
>  create mode 100644 include/linux/bvec.h
>
> --
> 1.9.1
>

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Re: [PATCH v5 0/8] block: prepare for multipage bvecs

[Christoph Hellwig]

On Tue, May 03, 2016 at 09:03:58AM +0800, Ming Lei wrote:
> Any possibility to make v5 into v4.7 so that we can move on about
> multipage bvecs?
> 
> BTW, even though not considering mp bvecs, this patchset is still a
> good cleanup.

Agreed.  I'm fine with the series and it looks harmless enough for
4.7.

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