From: Yu Kuai yukuai3@huawei.com
[ Upstream commit 2c27d09d3a76b33629d2e681bf8b774f776ade7f ]
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 paul.e.luse@linux.intel.com Signed-off-by: Paul Luse paul.e.luse@linux.intel.com Signed-off-by: Yu Kuai yukuai3@huawei.com Signed-off-by: Song Liu song@kernel.org Link: https://lore.kernel.org/r/20240229095714.926789-4-yukuai1@huaweicloud.com Stable-dep-of: 257ac239ffcf ("md/raid1: fix choose next idle in read_balance()") Signed-off-by: Sasha Levin sashal@kernel.org --- 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 8d881cc597992..27d187ca6258a 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 a560824e038b4..456d745eb93b3 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -602,7 +602,6 @@ 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; @@ -623,7 +622,6 @@ 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);
@@ -640,7 +638,6 @@ 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 @@ -706,8 +703,6 @@ 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) { @@ -734,7 +729,7 @@ 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 >= @@ -766,7 +761,7 @@ 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; @@ -1771,6 +1766,11 @@ 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; @@ -1794,6 +1794,9 @@ 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 14d4211a123a8..5300cbaa58a41 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;