diff options
| author | Ming Lin <ming.l@ssi.samsung.com> | 2015-05-06 22:51:24 -0700 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2015-08-13 12:31:51 -0600 |
| commit | 7ef6b12a1966f273afb750e19e1e8129bea48fec (patch) | |
| tree | b55c76f78bfe553966c2a07fe47ef8f0e94c4f77 /drivers/md | |
| parent | b49a0871be31a745b2ef7912653683a1876ff701 (diff) | |
| download | linux-7ef6b12a1966f273afb750e19e1e8129bea48fec.tar.bz2 | |
md/raid5: split bio for chunk_aligned_read
If a read request fits entirely in a chunk, it will be passed directly to the
underlying device (providing it hasn't failed of course). If it doesn't fit,
the slightly less efficient path that uses the stripe_cache is used.
Requests that get to the stripe cache are always completely split up as
necessary.
So with RAID5, ripping out the merge_bvec_fn doesn't cause it to stop work,
but could cause it to take the less efficient path more often.
All that is needed to manage this is for 'chunk_aligned_read' do some bio
splitting, much like the RAID0 code does.
Cc: Neil Brown <neilb@suse.de>
Cc: linux-raid@vger.kernel.org
Acked-by: NeilBrown <neilb@suse.de>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/raid5.c | 37 |
1 files changed, 32 insertions, 5 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 085db931aafc..256cc07f0874 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -4800,7 +4800,7 @@ static int bio_fits_rdev(struct bio *bi) return 1; } -static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio) +static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio) { struct r5conf *conf = mddev->private; int dd_idx; @@ -4809,7 +4809,7 @@ static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio) sector_t end_sector; if (!in_chunk_boundary(mddev, raid_bio)) { - pr_debug("chunk_aligned_read : non aligned\n"); + pr_debug("%s: non aligned\n", __func__); return 0; } /* @@ -4886,6 +4886,31 @@ static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio) } } +static struct bio *chunk_aligned_read(struct mddev *mddev, struct bio *raid_bio) +{ + struct bio *split; + + do { + sector_t sector = raid_bio->bi_iter.bi_sector; + unsigned chunk_sects = mddev->chunk_sectors; + unsigned sectors = chunk_sects - (sector & (chunk_sects-1)); + + if (sectors < bio_sectors(raid_bio)) { + split = bio_split(raid_bio, sectors, GFP_NOIO, fs_bio_set); + bio_chain(split, raid_bio); + } else + split = raid_bio; + + if (!raid5_read_one_chunk(mddev, split)) { + if (split != raid_bio) + generic_make_request(raid_bio); + return split; + } + } while (split != raid_bio); + + return NULL; +} + /* __get_priority_stripe - get the next stripe to process * * Full stripe writes are allowed to pass preread active stripes up until @@ -5163,9 +5188,11 @@ static void make_request(struct mddev *mddev, struct bio * bi) * data on failed drives. */ if (rw == READ && mddev->degraded == 0 && - mddev->reshape_position == MaxSector && - chunk_aligned_read(mddev,bi)) - return; + mddev->reshape_position == MaxSector) { + bi = chunk_aligned_read(mddev, bi); + if (!bi) + return; + } if (unlikely(bi->bi_rw & REQ_DISCARD)) { make_discard_request(mddev, bi); |