From: Bob Liu <[email protected]> * nr_mirrors that raid1 device support should be @raid_disks, init it properly. * Recording i/o went to which mirror in bio->bi_rw_hint. * Read from specific real device if bi_rw_hint was set.
Todo: * Support more drivers. Signed-off-by: Bob Liu <[email protected]> --- drivers/md/raid1.c | 31 ++++++++++++++++++++++++++++--- 1 file changed, 28 insertions(+), 3 deletions(-) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index fedf8c0..d2bdd0e 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -553,7 +553,8 @@ static sector_t align_to_barrier_unit_end(sector_t start_sector, * * The rdev for the device selected will have nr_pending incremented. */ -static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sectors) +static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sectors, + unsigned short disk_hint) { const sector_t this_sector = r1_bio->sector; int sectors; @@ -566,6 +567,7 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect struct md_rdev *rdev; int choose_first; int choose_next_idle; + int max_disks; rcu_read_lock(); /* @@ -593,7 +595,20 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect else choose_first = 0; - for (disk = 0 ; disk < conf->raid_disks * 2 ; disk++) { + if (disk_hint) { + disk = disk_hint - 1; + /* + * Consider replacement as a special case, use original device to + * indicate which mirror this i/o was happened. + */ + if (disk >= conf->raid_disks) + disk -= conf->raid_disks; + max_disks = disk + 1; + } else { + disk = 0; + max_disks = conf->raid_disks * 2; + } + for (; disk < max_disks; disk++) { sector_t dist; sector_t first_bad; int bad_sectors; @@ -1234,7 +1249,7 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio, * make_request() can abort the operation when read-ahead is being * used and no empty request is available. */ - rdisk = read_balance(conf, r1_bio, &max_sectors); + rdisk = read_balance(conf, r1_bio, &max_sectors, bio->bi_rw_hint); if (rdisk < 0) { /* couldn't find anywhere to read from */ @@ -1247,6 +1262,10 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio, raid_end_bio_io(r1_bio); return; } + + /* Recording i/o went to which real device. */ + bio->bi_rw_hint = rdisk; + mirror = conf->mirrors + rdisk; if (print_msg) @@ -1279,6 +1298,11 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio, r1_bio->read_disk = rdisk; read_bio = bio_clone_fast(bio, gfp, &mddev->bio_set); + /* + * Clear bi_rw_hint, because it was set last i/o went to which real + * device. + */ + read_bio->bi_rw_hint = 0; r1_bio->bios[rdisk] = read_bio; @@ -3078,6 +3102,7 @@ static int raid1_run(struct mddev *mddev) if (mddev->queue) { blk_queue_max_write_same_sectors(mddev->queue, 0); blk_queue_max_write_zeroes_sectors(mddev->queue, 0); + blk_queue_set_mirrors(mddev->queue, mddev->raid_disks); } rdev_for_each(rdev, mddev) { -- 2.7.4
