Commit dfa8ecd1 authored by Yu Kuai's avatar Yu Kuai Committed by Song Liu
Browse files

md/raid1: factor out choose_slow_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 slow rdev 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/20240229095714.926789-9-yukuai1@huaweicloud.com
parent 31a73331

drivers/md/raid1.c

+52 −17
Original line number Diff line number Diff line
@@ -620,6 +620,53 @@ static int choose_first_rdev(struct r1conf *conf, struct r1bio *r1_bio, 
	return -1;

}



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

			    int *max_sectors)

{

	sector_t this_sector = r1_bio->sector;

	int bb_disk = -1;

	int bb_read_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;



		/* there are no bad blocks, we can use this disk */

		len = r1_bio->sectors;

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

		if (read_len == r1_bio->sectors) {

			update_read_sectors(conf, disk, this_sector, read_len);

			return disk;

		}



		/*

		 * there are partial bad blocks, choose the rdev with largest

		 * read length.

		 */

		if (read_len > bb_read_len) {

			bb_disk = disk;

			bb_read_len = read_len;

		}

	}



	if (bb_disk != -1) {

		*max_sectors = bb_read_len;

		update_read_sectors(conf, bb_disk, this_sector, bb_read_len);

	}



	return bb_disk;

}



/*

 * This routine returns the disk from which the requested read should

 * be done. There is a per-array 'next expected sequential IO' sector
@@ -673,23 +720,8 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect 
		if (!test_bit(In_sync, &rdev->flags) &&

		    rdev->recovery_offset < this_sector + sectors)

			continue;

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

			/* Don't balance among write-mostly, just

			 * use the first as a last resort */

			if (best_dist_disk < 0) {

				if (is_badblock(rdev, this_sector, sectors,

						&first_bad, &bad_sectors)) {

					if (first_bad <= this_sector)

						/* Cannot use this */

						continue;

					best_good_sectors = first_bad - this_sector;

				} else

					best_good_sectors = sectors;

				best_dist_disk = disk;

				best_pending_disk = disk;

			}

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

			continue;

		}

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

		 * even be best.

		 */
@@ -808,7 +840,10 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect 
	}

	*max_sectors = sectors;



	if (best_disk >= 0)

		return best_disk;



	return choose_slow_rdev(conf, r1_bio, max_sectors);

}



static void wake_up_barrier(struct r1conf *conf)