+static void handle_read_error(mddev_t *mddev, r10bio_t *r10_bio)
+{
+ int slot = r10_bio->read_slot;
+ int mirror = r10_bio->devs[slot].devnum;
+ struct bio *bio;
+ conf_t *conf = mddev->private;
+ mdk_rdev_t *rdev;
+ char b[BDEVNAME_SIZE];
+ unsigned long do_sync;
+
+ /* 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.
+ */
+ if (mddev->ro == 0) {
+ freeze_array(conf);
+ fix_read_error(conf, mddev, r10_bio);
+ unfreeze_array(conf);
+ }
+ rdev_dec_pending(conf->mirrors[mirror].rdev, mddev);
+
+ bio = r10_bio->devs[slot].bio;
+ r10_bio->devs[slot].bio =
+ mddev->ro ? IO_BLOCKED : NULL;
+ mirror = read_balance(conf, r10_bio);
+ if (mirror == -1) {
+ printk(KERN_ALERT "md/raid10:%s: %s: unrecoverable I/O"
+ " read error for block %llu\n",
+ mdname(mddev),
+ bdevname(bio->bi_bdev, b),
+ (unsigned long long)r10_bio->sector);
+ raid_end_bio_io(r10_bio);
+ bio_put(bio);
+ return;
+ }
+
+ do_sync = (r10_bio->master_bio->bi_rw & REQ_SYNC);
+ bio_put(bio);
+ slot = r10_bio->read_slot;
+ rdev = conf->mirrors[mirror].rdev;
+ printk_ratelimited(
+ KERN_ERR
+ "md/raid10:%s: %s: redirecting"
+ "sector %llu to another mirror\n",
+ mdname(mddev),
+ bdevname(rdev->bdev, b),
+ (unsigned long long)r10_bio->sector);
+ bio = bio_clone_mddev(r10_bio->master_bio,
+ GFP_NOIO, mddev);
+ r10_bio->devs[slot].bio = bio;
+ bio->bi_sector = r10_bio->devs[slot].addr
+ + rdev->data_offset;
+ bio->bi_bdev = rdev->bdev;
+ bio->bi_rw = READ | do_sync;
+ bio->bi_private = r10_bio;
+ bio->bi_end_io = raid10_end_read_request;
+ generic_make_request(bio);
+}
+