[PATCH v2 0/5] md: use bio_clone_fast()

From: Ming Lei
Date: Tue Feb 14 2017 - 10:29:24 EST


This patches replaces bio_clone() with bio_fast_clone() in
bio_clone_mddev() because:

1) bio_clone_mddev() is used in raid normal I/O and isn't in
resync I/O path, and all the direct access to bvec table in
raid happens on resync I/O only except for write behind of raid1.
Write behind is treated specially, so the replacement is safe.

2) for write behind, bio_clone() is kept, but this patchset
introduces bio_clone_bioset_partial() to just clone one specific
bvecs range instead of whole table. Then write behind is improved

1) move 3rd patch into 2nd one
2) kill bio_clone_mddev() and use bio_clone_fast() directly
3) define local variable 'offset' as sector_t in raid1_write_request()

1) don't introduce bio_clone_slow_mddev_partial()
2) return failure if mddev->bio_set can't be created
3) remove check in bio_clone_mddev() as suggested by
Christoph Hellwig.
4) rename bio_clone_mddev() as bio_clone_fast_mddev()

Ming Lei (5):
block: introduce bio_clone_bioset_partial()
md: fail if mddev->bio_set can't be created
md/raid1: use bio_clone_bioset_partial() in case of write behind
md: remove unnecessary check on mddev
md: fast clone bio in bio_clone_mddev()

block/bio.c | 61 +++++++++++++++++++++++++++++++++++++++++------------
drivers/md/faulty.c | 2 +-
drivers/md/md.c | 15 ++++---------
drivers/md/md.h | 2 --
drivers/md/raid1.c | 28 +++++++++++++++++-------
drivers/md/raid10.c | 11 +++++-----
drivers/md/raid5.c | 4 ++--
include/linux/bio.h | 11 ++++++++--
8 files changed, 89 insertions(+), 45 deletions(-)