From: Yu Kuai <yukuai3@xxxxxxxxxx>
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: Paul Luse <paul.e.luse@xxxxxxxxxxxxxxx>
Signed-off-by: Paul Luse <paul.e.luse@xxxxxxxxxxxxxxx>
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Reviewed-by: Xiao Ni <xni@xxxxxxxxxx>
---
drivers/md/raid1.c | 79 ++++++++++++++++++++++++++++------------------
1 file changed, 48 insertions(+), 31 deletions(-)
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 09b7e93a54b5..f6e75c123e5a 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -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 */
- 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;
- }
- }
+ if (rdev_has_badblock(rdev, this_sector, sectors))
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);
}
--
2.39.2
