md/raid5: use bad-block log to improve handling of uncorrectable read errors.

If we get an uncorrectable read error - record a bad block rather than
failing the device.
And if these errors (which may be due to known bad blocks) cause
recovery to be impossible, record a bad block on the recovering
devices, or abort the recovery.

As we might abort a recovery without failing a device we need to teach
RAID5 about recovery_disabled handling.

Signed-off-by: NeilBrown <neilb@suse.de>

2 files changed, 53 insertions, 8 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index a2d68389ee75..5fc621673e6c 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2232,9 +2232,18 @@ handle_failed_stripe(raid5_conf_t *conf, struct stripe_head *sh,
                         rcu_read_lock();
                         rdev = rcu_dereference(conf->disks[i].rdev);
                         if (rdev && test_bit(In_sync, &rdev->flags))
-                                /* multiple read failures in one stripe */
-                                md_error(conf->mddev, rdev);
+                                atomic_inc(&rdev->nr_pending);
+                        else
+                                rdev = NULL;
                         rcu_read_unlock();
+                        if (rdev) {
+                                if (!rdev_set_badblocks(
+                                            rdev,
+                                            sh->sector,
+                                            STRIPE_SECTORS, 0))
+                                        md_error(conf->mddev, rdev);
+                                rdev_dec_pending(rdev, conf->mddev);
+                        }
                 }
                 spin_lock_irq(&conf->device_lock);
                 /* fail all writes first */
@@ -2313,6 +2322,41 @@ handle_failed_stripe(raid5_conf_t *conf, struct stripe_head *sh,
                         md_wakeup_thread(conf->mddev->thread);
 }
 
+static void
+handle_failed_sync(raid5_conf_t *conf, struct stripe_head *sh,
+                   struct stripe_head_state *s)
+{
+        int abort = 0;
+        int i;
+
+        md_done_sync(conf->mddev, STRIPE_SECTORS, 0);
+        clear_bit(STRIPE_SYNCING, &sh->state);
+        s->syncing = 0;
+        /* There is nothing more to do for sync/check/repair.
+         * For recover we need to record a bad block on all
+         * non-sync devices, or abort the recovery
+         */
+        if (!test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery))
+                return;
+        /* During recovery devices cannot be removed, so locking and
+         * refcounting of rdevs is not needed
+         */
+        for (i = 0; i < conf->raid_disks; i++) {
+                mdk_rdev_t *rdev = conf->disks[i].rdev;
+                if (!rdev
+                    || test_bit(Faulty, &rdev->flags)
+                    || test_bit(In_sync, &rdev->flags))
+                        continue;
+                if (!rdev_set_badblocks(rdev, sh->sector,
+                                        STRIPE_SECTORS, 0))
+                        abort = 1;
+        }
+        if (abort) {
+                conf->recovery_disabled = conf->mddev->recovery_disabled;
+                set_bit(MD_RECOVERY_INTR, &conf->mddev->recovery);
+        }
+}
+
 /* fetch_block - checks the given member device to see if its data needs
  * to be read or computed to satisfy a request.
  *
@@ -3067,11 +3111,8 @@ static void handle_stripe(struct stripe_head *sh)
          */
         if (s.failed > conf->max_degraded && s.to_read+s.to_write+s.written)
                 handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
-        if (s.failed > conf->max_degraded && s.syncing) {
-                md_done_sync(conf->mddev, STRIPE_SECTORS, 0);
-                clear_bit(STRIPE_SYNCING, &sh->state);
-                s.syncing = 0;
-        }
+        if (s.failed > conf->max_degraded && s.syncing)
+                handle_failed_sync(conf, sh, &s);
 
         /*
          * might be able to return some write requests if the parity blocks
@@ -4976,6 +5017,7 @@ static int raid5_remove_disk(mddev_t *mddev, int number)
                  * isn't possible.
                  */
                 if (!test_bit(Faulty, &rdev->flags) &&
+                    mddev->recovery_disabled != conf->recovery_disabled &&
                     !has_failed(conf) &&
                     number < conf->raid_disks) {
                         err = -EBUSY;
@@ -5004,6 +5046,9 @@ static int raid5_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
         int first = 0;
         int last = conf->raid_disks - 1;
 
+        if (mddev->recovery_disabled == conf->recovery_disabled)
+                return -EBUSY;
+
         if (has_failed(conf))
                 /* no point adding a device */
                 return -EINVAL;
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 68c500af1108..c5429d123636 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -399,7 +399,7 @@ struct raid5_private_data {
                                             * (fresh device added).
                                             * Cleared when a sync completes.
                                             */
-
+        int                     recovery_disabled;
         /* per cpu variables */
         struct raid5_percpu {
                 struct page     *spare_page; /* Used when checking P/Q in raid6 */