Commit 2c27d09d authored by Yu Kuai's avatar Yu Kuai Committed by Song Liu
Browse files

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: default avatarPaul Luse <paul.e.luse@linux.intel.com>
Signed-off-by: default avatarPaul Luse <paul.e.luse@linux.intel.com>
Signed-off-by: default avatarYu Kuai <yukuai3@huawei.com>
Signed-off-by: default avatarSong Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240229095714.926789-4-yukuai1@huaweicloud.com
parent 969d6589

drivers/md/md.h

+1 −0
Original line number Diff line number Diff line
@@ -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,

drivers/md/raid1.c

+10 −7
Original line number Diff line number Diff line
@@ -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;

}

drivers/md/raid1.h

+1 −0
Original line number Diff line number Diff line
@@ -71,6 +71,7 @@ struct r1conf { 
						 * allow for replacements.

						 */

	int			raid_disks;

	int			nonrot_disks;



	spinlock_t		device_lock;