From 2c27d09d3a76b33629d2e681bf8b774f776ade7f Mon Sep 17 00:00:00 2001 From: Yu Kuai Date: Thu, 29 Feb 2024 17:57:06 +0800 Subject: [PATCH] md/raid1: record nonrot rdevs while adding/removing rdevs to conf For raid1, each read will iterate all the rdevs from conf and check if any rdev is non-rotational, then choose rdev with minimal IO inflight if so, or rdev with closest distance otherwise. Disk nonrot info can be changed through sysfs entry: /sys/block/[disk_name]/queue/rotational However, consider that this should only be used for testing, and user really shouldn't do this in real life. Record the number of non-rotational disks in conf, to avoid checking each rdev in IO fast path and simplify read_balance() a little bit. Co-developed-by: Paul Luse Signed-off-by: Paul Luse Signed-off-by: Yu Kuai Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20240229095714.926789-4-yukuai1@huaweicloud.com --- drivers/md/md.h | 1 + drivers/md/raid1.c | 17 ++++++++++------- drivers/md/raid1.h | 1 + 3 files changed, 12 insertions(+), 7 deletions(-) diff --git a/drivers/md/md.h b/drivers/md/md.h index a49ab04ab707..b2076a165c10 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -207,6 +207,7 @@ enum flag_bits { * check if there is collision between raid1 * serial bios. */ + Nonrot, /* non-rotational device (SSD) */ }; static inline int is_badblock(struct md_rdev *rdev, sector_t s, int sectors, diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 6ec9998f6257..de6ea87d4d24 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -599,7 +599,6 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect int sectors; int best_good_sectors; int best_disk, best_dist_disk, best_pending_disk; - int has_nonrot_disk; int disk; sector_t best_dist; unsigned int min_pending; @@ -620,7 +619,6 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect best_pending_disk = -1; min_pending = UINT_MAX; best_good_sectors = 0; - has_nonrot_disk = 0; choose_next_idle = 0; clear_bit(R1BIO_FailFast, &r1_bio->state); @@ -637,7 +635,6 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect sector_t first_bad; int bad_sectors; unsigned int pending; - bool nonrot; rdev = conf->mirrors[disk].rdev; if (r1_bio->bios[disk] == IO_BLOCKED @@ -703,8 +700,6 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect /* At least two disks to choose from so failfast is OK */ set_bit(R1BIO_FailFast, &r1_bio->state); - nonrot = bdev_nonrot(rdev->bdev); - has_nonrot_disk |= nonrot; pending = atomic_read(&rdev->nr_pending); dist = abs(this_sector - conf->mirrors[disk].head_position); if (choose_first) { @@ -731,7 +726,7 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect * small, but not a big deal since when the second disk * starts IO, the first disk is likely still busy. */ - if (nonrot && opt_iosize > 0 && + if (test_bit(Nonrot, &rdev->flags) && opt_iosize > 0 && mirror->seq_start != MaxSector && mirror->next_seq_sect > opt_iosize && mirror->next_seq_sect - opt_iosize >= @@ -763,7 +758,7 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect * mixed ratation/non-rotational disks depending on workload. */ if (best_disk == -1) { - if (has_nonrot_disk || min_pending == 0) + if (READ_ONCE(conf->nonrot_disks) || min_pending == 0) best_disk = best_pending_disk; else best_disk = best_dist_disk; @@ -1768,6 +1763,11 @@ static bool raid1_add_conf(struct r1conf *conf, struct md_rdev *rdev, int disk, if (info->rdev) return false; + if (bdev_nonrot(rdev->bdev)) { + set_bit(Nonrot, &rdev->flags); + WRITE_ONCE(conf->nonrot_disks, conf->nonrot_disks + 1); + } + rdev->raid_disk = disk; info->head_position = 0; info->seq_start = MaxSector; @@ -1791,6 +1791,9 @@ static bool raid1_remove_conf(struct r1conf *conf, int disk) rdev->mddev->degraded < conf->raid_disks) return false; + if (test_and_clear_bit(Nonrot, &rdev->flags)) + WRITE_ONCE(conf->nonrot_disks, conf->nonrot_disks - 1); + WRITE_ONCE(info->rdev, NULL); return true; } diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h index 14d4211a123a..5300cbaa58a4 100644 --- a/drivers/md/raid1.h +++ b/drivers/md/raid1.h @@ -71,6 +71,7 @@ struct r1conf { * allow for replacements. */ int raid_disks; + int nonrot_disks; spinlock_t device_lock;