diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/md/raid5.c | 45 |
1 files changed, 44 insertions, 1 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 7b820b81d8c2..f787c9e5b10e 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -6079,6 +6079,38 @@ out_release: return ret; } +/* + * If the bio covers multiple data disks, find sector within the bio that has + * the lowest chunk offset in the first chunk. + */ +static sector_t raid5_bio_lowest_chunk_sector(struct r5conf *conf, + struct bio *bi) +{ + int sectors_per_chunk = conf->chunk_sectors; + int raid_disks = conf->raid_disks; + int dd_idx; + struct stripe_head sh; + unsigned int chunk_offset; + sector_t r_sector = bi->bi_iter.bi_sector & ~((sector_t)RAID5_STRIPE_SECTORS(conf)-1); + sector_t sector; + + /* We pass in fake stripe_head to get back parity disk numbers */ + sector = raid5_compute_sector(conf, r_sector, 0, &dd_idx, &sh); + chunk_offset = sector_div(sector, sectors_per_chunk); + if (sectors_per_chunk - chunk_offset >= bio_sectors(bi)) + return r_sector; + /* + * Bio crosses to the next data disk. Check whether it's in the same + * chunk. + */ + dd_idx++; + while (dd_idx == sh.pd_idx || dd_idx == sh.qd_idx) + dd_idx++; + if (dd_idx >= raid_disks) + return r_sector; + return r_sector + sectors_per_chunk - chunk_offset; +} + static bool raid5_make_request(struct mddev *mddev, struct bio * bi) { DEFINE_WAIT_FUNC(wait, woken_wake_function); @@ -6150,6 +6182,17 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi) } md_account_bio(mddev, &bi); + /* + * Lets start with the stripe with the lowest chunk offset in the first + * chunk. That has the best chances of creating IOs adjacent to + * previous IOs in case of sequential IO and thus creates the most + * sequential IO pattern. We don't bother with the optimization when + * reshaping as the performance benefit is not worth the complexity. + */ + if (likely(conf->reshape_progress == MaxSector)) + logical_sector = raid5_bio_lowest_chunk_sector(conf, bi); + s = (logical_sector - ctx.first_sector) >> RAID5_STRIPE_SHIFT(conf); + add_wait_queue(&conf->wait_for_overlap, &wait); while (1) { res = make_stripe_request(mddev, conf, &ctx, logical_sector, @@ -6178,7 +6221,7 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi) continue; } - s = find_first_bit(ctx.sectors_to_do, stripe_cnt); + s = find_next_bit_wrap(ctx.sectors_to_do, stripe_cnt, s); if (s == stripe_cnt) break; |