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Commit d4432c23 authored by NeilBrown's avatar NeilBrown
Browse files

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: default avatarNeilBrown <neilb@suse.de>
parent e875ecea
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+93 −12
Original line number Diff line number Diff line
@@ -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 @@ static int make_request(mddev_t *mddev, struct bio * bio)
			/* 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;
@@ -963,6 +962,13 @@ static int make_request(mddev_t *mddev, struct bio * bio)
	/* 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);

@@ -970,6 +976,8 @@ static int make_request(mddev_t *mddev, struct bio * bio)
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 @@ static int make_request(mddev_t *mddev, struct bio * bio)
			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;
		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 @@ static int make_request(mddev_t *mddev, struct bio * bio)
		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 @@ static int make_request(mddev_t *mddev, struct bio * bio)
			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 @@ static int make_request(mddev_t *mddev, struct bio * bio)
	/* 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;