+ /* we got a read error. Maybe the drive is bad. Maybe just
+ * the block and we can fix it.
+ * We freeze all other IO, and try reading the block from
+ * other devices. When we find one, we re-write
+ * and check it that fixes the read error.
+ * This is all done synchronously while the array is
+ * frozen.
+ */
+ int sect = 0; /* Offset from r10_bio->sector */
+ int sectors = r10_bio->sectors;
+ freeze_array(conf);
+ if (mddev->ro == 0) while(sectors) {
+ int s = sectors;
+ int sl = r10_bio->read_slot;
+ int success = 0;
+
+ if (s > (PAGE_SIZE>>9))
+ s = PAGE_SIZE >> 9;
+
+ rcu_read_lock();
+ do {
+ int d = r10_bio->devs[sl].devnum;
+ rdev = rcu_dereference(conf->mirrors[d].rdev);
+ if (rdev &&
+ test_bit(In_sync, &rdev->flags)) {
+ atomic_inc(&rdev->nr_pending);
+ rcu_read_unlock();
+ success = sync_page_io(rdev->bdev,
+ r10_bio->devs[sl].addr +
+ sect + rdev->data_offset,
+ s<<9,
+ conf->tmppage, READ);
+ rdev_dec_pending(rdev, mddev);
+ rcu_read_lock();
+ if (success)
+ break;
+ }
+ sl++;
+ if (sl == conf->copies)
+ sl = 0;
+ } while (!success && sl != r10_bio->read_slot);
+ rcu_read_unlock();
+
+ if (success) {
+ int start = sl;
+ /* write it back and re-read */
+ rcu_read_lock();
+ while (sl != r10_bio->read_slot) {
+ int d;
+ if (sl==0)
+ sl = conf->copies;
+ sl--;
+ d = r10_bio->devs[sl].devnum;
+ rdev = rcu_dereference(conf->mirrors[d].rdev);
+ if (rdev &&
+ test_bit(In_sync, &rdev->flags)) {
+ atomic_inc(&rdev->nr_pending);
+ rcu_read_unlock();
+ atomic_add(s, &rdev->corrected_errors);
+ if (sync_page_io(rdev->bdev,
+ r10_bio->devs[sl].addr +
+ sect + rdev->data_offset,
+ s<<9, conf->tmppage, WRITE) == 0)
+ /* Well, this device is dead */
+ md_error(mddev, rdev);
+ rdev_dec_pending(rdev, mddev);
+ rcu_read_lock();
+ }
+ }
+ sl = start;
+ while (sl != r10_bio->read_slot) {
+ int d;
+ if (sl==0)
+ sl = conf->copies;
+ sl--;
+ d = r10_bio->devs[sl].devnum;
+ rdev = rcu_dereference(conf->mirrors[d].rdev);
+ if (rdev &&
+ test_bit(In_sync, &rdev->flags)) {
+ atomic_inc(&rdev->nr_pending);
+ rcu_read_unlock();
+ if (sync_page_io(rdev->bdev,
+ r10_bio->devs[sl].addr +
+ sect + rdev->data_offset,
+ s<<9, conf->tmppage, READ) == 0)
+ /* Well, this device is dead */
+ md_error(mddev, rdev);
+ rdev_dec_pending(rdev, mddev);
+ rcu_read_lock();
+ }
+ }
+ rcu_read_unlock();
+ } else {
+ /* Cannot read from anywhere -- bye bye array */
+ md_error(mddev, conf->mirrors[r10_bio->devs[r10_bio->read_slot].devnum].rdev);
+ break;
+ }
+ sectors -= s;
+ sect += s;
+ }
+
+ unfreeze_array(conf);
+