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

[Ming Lei <ming.lei@canonical.com>]

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