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

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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: 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>
Reviewed-by: Xiao Ni <xni@redhat.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240229095714.926789-9-yukuai1@huaweicloud.com
This commit is contained in:
Yu Kuai 2024-02-29 17:57:11 +08:00 committed by Song Liu
parent 31a7333175
commit dfa8ecd167
1 changed files with 52 additions and 17 deletions
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67
drivers/md/raid1.c
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@ -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 */
if (test_bit(WriteMostly, &rdev->flags))
continue;
best_good_sectors = first_bad - this_sector;
} else
best_good_sectors = sectors;
best_dist_disk = disk;
best_pending_disk = disk;
}
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)