md/raid10: avoid writing to known bad blocks on known bad drives.

Writing to known bad blocks on drives that have seen a write error
is asking for trouble.  So try to avoid these blocks.

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

1 files changed, 93 insertions, 12 deletions

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index de6089926273..13077a3fd7d2 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -807,6 +807,8 @@ static int make_request(mddev_t *mddev, struct bio * bio)
         unsigned long flags;
         mdk_rdev_t *blocked_rdev;
         int plugged;
+        int sectors_handled;
+        int max_sectors;
 
         if (unlikely(bio->bi_rw & REQ_FLUSH)) {
                 md_flush_request(mddev, bio);
@@ -895,7 +897,6 @@ static int make_request(mddev_t *mddev, struct bio * bio)
                 /*
                  * read balancing logic:
                  */
-                int max_sectors;
                 int disk;
                 int slot;
 
@@ -925,8 +926,6 @@ read_again:
                         /* Could not read all from this device, so we will
                          * need another r10_bio.
                          */
-                        int sectors_handled;
-
                         sectors_handled = (r10_bio->sectors + max_sectors
                                            - bio->bi_sector);
                         r10_bio->sectors = max_sectors;
@@ -963,13 +962,22 @@ read_again:
         /* first select target devices under rcu_lock and
          * inc refcount on their rdev.  Record them by setting
          * bios[x] to bio
+         * If there are known/acknowledged bad blocks on any device
+         * on which we have seen a write error, we want to avoid
+         * writing to those blocks.  This potentially requires several
+         * writes to write around the bad blocks.  Each set of writes
+         * gets its own r10_bio with a set of bios attached.  The number
+         * of r10_bios is recored in bio->bi_phys_segments just as with
+         * the read case.
          */
         plugged = mddev_check_plugged(mddev);
 
         raid10_find_phys(conf, r10_bio);
- retry_write:
+retry_write:
         blocked_rdev = NULL;
         rcu_read_lock();
+        max_sectors = r10_bio->sectors;
+
         for (i = 0;  i < conf->copies; i++) {
                 int d = r10_bio->devs[i].devnum;
                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[d].rdev);
@@ -978,13 +986,55 @@ read_again:
                         blocked_rdev = rdev;
                         break;
                 }
-                if (rdev && !test_bit(Faulty, &rdev->flags)) {
-                        atomic_inc(&rdev->nr_pending);
-                        r10_bio->devs[i].bio = bio;
-                } else {
-                        r10_bio->devs[i].bio = NULL;
+                r10_bio->devs[i].bio = NULL;
+                if (!rdev || test_bit(Faulty, &rdev->flags)) {
                         set_bit(R10BIO_Degraded, &r10_bio->state);
+                        continue;
+                }
+                if (test_bit(WriteErrorSeen, &rdev->flags)) {
+                        sector_t first_bad;
+                        sector_t dev_sector = r10_bio->devs[i].addr;
+                        int bad_sectors;
+                        int is_bad;
+
+                        is_bad = is_badblock(rdev, dev_sector,
+                                             max_sectors,
+                                             &first_bad, &bad_sectors);
+                        if (is_bad < 0) {
+                                /* Mustn't write here until the bad block
+                                 * is acknowledged
+                                 */
+                                atomic_inc(&rdev->nr_pending);
+                                set_bit(BlockedBadBlocks, &rdev->flags);
+                                blocked_rdev = rdev;
+                                break;
+                        }
+                        if (is_bad && first_bad <= dev_sector) {
+                                /* Cannot write here at all */
+                                bad_sectors -= (dev_sector - first_bad);
+                                if (bad_sectors < max_sectors)
+                                        /* Mustn't write more than bad_sectors
+                                         * to other devices yet
+                                         */
+                                        max_sectors = bad_sectors;
+                                /* We don't set R10BIO_Degraded as that
+                                 * only applies if the disk is missing,
+                                 * so it might be re-added, and we want to
+                                 * know to recover this chunk.
+                                 * In this case the device is here, and the
+                                 * fact that this chunk is not in-sync is
+                                 * recorded in the bad block log.
+                                 */
+                                continue;
+                        }
+                        if (is_bad) {
+                                int good_sectors = first_bad - dev_sector;
+                                if (good_sectors < max_sectors)
+                                        max_sectors = good_sectors;
+                        }
                 }
+                r10_bio->devs[i].bio = bio;
+                atomic_inc(&rdev->nr_pending);
         }
         rcu_read_unlock();
 
@@ -1004,8 +1054,22 @@ read_again:
                 goto retry_write;
         }
 
+        if (max_sectors < r10_bio->sectors) {
+                /* We are splitting this into multiple parts, so
+                 * we need to prepare for allocating another r10_bio.
+                 */
+                r10_bio->sectors = max_sectors;
+                spin_lock_irq(&conf->device_lock);
+                if (bio->bi_phys_segments == 0)
+                        bio->bi_phys_segments = 2;
+                else
+                        bio->bi_phys_segments++;
+                spin_unlock_irq(&conf->device_lock);
+        }
+        sectors_handled = r10_bio->sector + max_sectors - bio->bi_sector;
+
         atomic_set(&r10_bio->remaining, 1);
-        bitmap_startwrite(mddev->bitmap, bio->bi_sector, r10_bio->sectors, 0);
+        bitmap_startwrite(mddev->bitmap, r10_bio->sector, r10_bio->sectors, 0);
 
         for (i = 0; i < conf->copies; i++) {
                 struct bio *mbio;
@@ -1014,10 +1078,12 @@ read_again:
                         continue;
 
                 mbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
+                md_trim_bio(mbio, r10_bio->sector - bio->bi_sector,
+                            max_sectors);
                 r10_bio->devs[i].bio = mbio;
 
-                mbio->bi_sector = r10_bio->devs[i].addr+
-                        conf->mirrors[d].rdev->data_offset;
+                mbio->bi_sector = (r10_bio->devs[i].addr+
+                                   conf->mirrors[d].rdev->data_offset);
                 mbio->bi_bdev = conf->mirrors[d].rdev->bdev;
                 mbio->bi_end_io = raid10_end_write_request;
                 mbio->bi_rw = WRITE | do_sync | do_fua;
@@ -1042,6 +1108,21 @@ read_again:
         /* In case raid10d snuck in to freeze_array */
         wake_up(&conf->wait_barrier);
 
+        if (sectors_handled < (bio->bi_size >> 9)) {
+                /* We need another r1_bio.  It has already been counted
+                 * in bio->bi_phys_segments.
+                 */
+                r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
+
+                r10_bio->master_bio = bio;
+                r10_bio->sectors = (bio->bi_size >> 9) - sectors_handled;
+
+                r10_bio->mddev = mddev;
+                r10_bio->sector = bio->bi_sector + sectors_handled;
+                r10_bio->state = 0;
+                goto retry_write;
+        }
+
         if (do_sync || !mddev->bitmap || !plugged)
                 md_wakeup_thread(mddev->thread);
         return 0;