Commit 9f3ced79 authored by Yu Kuai's avatar Yu Kuai Committed by Song Liu
Browse files

md/raid1: factor out choose_bb_rdev() from read_balance() 



read_balance() is hard to understand because there are too many status
and branches, and it's overlong.

This patch factor out the case to read the rdev with bad blocks from
read_balance(), there are no functional changes.

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>
Reviewed-by: default avatarXiao Ni <xni@redhat.com>
Signed-off-by: default avatarSong Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240229095714.926789-10-yukuai1@huaweicloud.com
parent dfa8ecd1

drivers/md/raid1.c

+48 −31
Original line number Diff line number Diff line
@@ -620,6 +620,44 @@ static int choose_first_rdev(struct r1conf *conf, struct r1bio *r1_bio, 
	return -1;

}



static int choose_bb_rdev(struct r1conf *conf, struct r1bio *r1_bio,

			  int *max_sectors)

{

	sector_t this_sector = r1_bio->sector;

	int best_disk = -1;

	int best_len = 0;

	int disk;



	for (disk = 0 ; disk < conf->raid_disks * 2 ; disk++) {

		struct md_rdev *rdev;

		int len;

		int read_len;



		if (r1_bio->bios[disk] == IO_BLOCKED)

			continue;



		rdev = conf->mirrors[disk].rdev;

		if (!rdev || test_bit(Faulty, &rdev->flags) ||

		    test_bit(WriteMostly, &rdev->flags))

			continue;



		/* keep track of the disk with the most readable sectors. */

		len = r1_bio->sectors;

		read_len = raid1_check_read_range(rdev, this_sector, &len);

		if (read_len > best_len) {

			best_disk = disk;

			best_len = read_len;

		}

	}



	if (best_disk != -1) {

		*max_sectors = best_len;

		update_read_sectors(conf, best_disk, this_sector, best_len);

	}



	return best_disk;

}



static int choose_slow_rdev(struct r1conf *conf, struct r1bio *r1_bio,

			    int *max_sectors)

{
@@ -708,8 +746,6 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect 


	for (disk = 0 ; disk < conf->raid_disks * 2 ; disk++) {

		sector_t dist;

		sector_t first_bad;

		int bad_sectors;

		unsigned int pending;



		rdev = conf->mirrors[disk].rdev;
@@ -722,36 +758,8 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect 
			continue;

		if (test_bit(WriteMostly, &rdev->flags))

			continue;

		/* This is a reasonable device to use.  It might

		 * even be best.

		 */

		if (is_badblock(rdev, this_sector, sectors,

				&first_bad, &bad_sectors)) {

			if (best_dist < MaxSector)

				/* already have a better device */

		if (rdev_has_badblock(rdev, this_sector, sectors))

			continue;

			if (first_bad <= this_sector) {

				/* cannot read here. If this is the 'primary'

				 * device, then we must not read beyond

				 * bad_sectors from another device..

				 */

				bad_sectors -= (this_sector - first_bad);

				if (best_good_sectors > sectors)

					best_good_sectors = sectors;



			} else {

				sector_t good_sectors = first_bad - this_sector;

				if (good_sectors > best_good_sectors) {

					best_good_sectors = good_sectors;

					best_disk = disk;

				}

			}

			continue;

		} else {

			if ((sectors > best_good_sectors) && (best_disk >= 0))

				best_disk = -1;

			best_good_sectors = sectors;

		}



		if (best_disk >= 0)

			/* At least two disks to choose from so failfast is OK */
@@ -843,6 +851,15 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect 
	if (best_disk >= 0)

		return best_disk;



	/*

	 * If we are here it means we didn't find a perfectly good disk so

	 * now spend a bit more time trying to find one with the most good

	 * sectors.

	 */

	disk = choose_bb_rdev(conf, r1_bio, max_sectors);

	if (disk >= 0)

		return disk;



	return choose_slow_rdev(conf, r1_bio, max_sectors);

}