md/raid10: handle further errors during fix_read_error better.

If we find more read/write errors we should record a bad block before
failing the device.
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/raid10.c

@@ -1749,6 +1749,26 @@ static void check_decay_read_errors(mddev_t *mddev, mdk_rdev_t *rdev)
 		atomic_set(&rdev->read_errors, read_errors >> hours_since_last);
 }
 
+static int r10_sync_page_io(mdk_rdev_t *rdev, sector_t sector,
+			    int sectors, struct page *page, int rw)
+{
+	sector_t first_bad;
+	int bad_sectors;
+
+	if (is_badblock(rdev, sector, sectors, &first_bad, &bad_sectors)
+	    && (rw == READ || test_bit(WriteErrorSeen, &rdev->flags)))
+		return -1;
+	if (sync_page_io(rdev, sector, sectors << 9, page, rw, false))
+		/* success */
+		return 1;
+	if (rw == WRITE)
+		set_bit(WriteErrorSeen, &rdev->flags);
+	/* need to record an error - either for the block or the device */
+	if (!rdev_set_badblocks(rdev, sector, sectors, 0))
+		md_error(rdev->mddev, rdev);
+	return 0;
+}
+
 /*
  * This is a kernel thread which:
  *
@@ -1832,9 +1852,19 @@ static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
 		rcu_read_unlock();
 
 		if (!success) {
-			/* Cannot read from anywhere -- bye bye array */
+			/* Cannot read from anywhere, just mark the block
+			 * as bad on the first device to discourage future
+			 * reads.
+			 */
 			int dn = r10_bio->devs[r10_bio->read_slot].devnum;
-			md_error(mddev, conf->mirrors[dn].rdev);
+			rdev = conf->mirrors[dn].rdev;
+
+			if (!rdev_set_badblocks(
+				    rdev,
+				    r10_bio->devs[r10_bio->read_slot].addr
+				    + sect,
+				    s, 0))
+				md_error(mddev, rdev);
 			break;
 		}
 
@@ -1855,10 +1885,10 @@ static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
 
 			atomic_inc(&rdev->nr_pending);
 			rcu_read_unlock();
-			if (sync_page_io(rdev,
+			if (r10_sync_page_io(rdev,
 					     r10_bio->devs[sl].addr +
 					     sect,
-					 s<<9, conf->tmppage, WRITE, false)
+					     s<<9, conf->tmppage, WRITE)
 			    == 0) {
 				/* Well, this device is dead */
 				printk(KERN_NOTICE
@@ -1873,7 +1903,6 @@ static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
 				       "drive\n",
 				       mdname(mddev),
 				       bdevname(rdev->bdev, b));
-				md_error(mddev, rdev);
 			}
 			rdev_dec_pending(rdev, mddev);
 			rcu_read_lock();
@@ -1893,11 +1922,12 @@ static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
 
 			atomic_inc(&rdev->nr_pending);
 			rcu_read_unlock();
-			if (sync_page_io(rdev,
+			switch (r10_sync_page_io(rdev,
 					     r10_bio->devs[sl].addr +
 					     sect,
 					     s<<9, conf->tmppage,
-					 READ, false) == 0) {
+						 READ)) {
+			case 0:
 				/* Well, this device is dead */
 				printk(KERN_NOTICE
 				       "md/raid10:%s: unable to read back "
@@ -1911,9 +1941,8 @@ static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
 				       "drive\n",
 				       mdname(mddev),
 				       bdevname(rdev->bdev, b));
-
-				md_error(mddev, rdev);
-			} else {
+				break;
+			case 1:
 				printk(KERN_INFO
 				       "md/raid10:%s: read error corrected"
 				       " (%d sectors at %llu on %s)\n",