1 files changed, 903 insertions, 280 deletions

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 6e846688962f..8b29cd4f01c8 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -22,6 +22,7 @@
 #include <linux/delay.h>
 #include <linux/blkdev.h>
 #include <linux/seq_file.h>
+#include <linux/ratelimit.h>
 #include "md.h"
 #include "raid10.h"
 #include "raid0.h"
@@ -123,7 +124,14 @@ static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
 	for (j = 0 ; j < nalloc; j++) {
 		bio = r10_bio->devs[j].bio;
 		for (i = 0; i < RESYNC_PAGES; i++) {
-			page = alloc_page(gfp_flags);
+			if (j == 1 && !test_bit(MD_RECOVERY_SYNC,
+						&conf->mddev->recovery)) {
+				/* we can share bv_page's during recovery */
+				struct bio *rbio = r10_bio->devs[0].bio;
+				page = rbio->bi_io_vec[i].bv_page;
+				get_page(page);
+			} else
+				page = alloc_page(gfp_flags);
 			if (unlikely(!page))
 				goto out_free_pages;
 
@@ -173,7 +181,7 @@ static void put_all_bios(conf_t *conf, r10bio_t *r10_bio)
 
 	for (i = 0; i < conf->copies; i++) {
 		struct bio **bio = & r10_bio->devs[i].bio;
-		if (*bio && *bio != IO_BLOCKED)
+		if (!BIO_SPECIAL(*bio))
 			bio_put(*bio);
 		*bio = NULL;
 	}
@@ -183,12 +191,6 @@ static void free_r10bio(r10bio_t *r10_bio)
 {
 	conf_t *conf = r10_bio->mddev->private;
 
-	/*
-	 * Wake up any possible resync thread that waits for the device
-	 * to go idle.
-	 */
-	allow_barrier(conf);
-
 	put_all_bios(conf, r10_bio);
 	mempool_free(r10_bio, conf->r10bio_pool);
 }
@@ -227,9 +229,27 @@ static void reschedule_retry(r10bio_t *r10_bio)
 static void raid_end_bio_io(r10bio_t *r10_bio)
 {
 	struct bio *bio = r10_bio->master_bio;
+	int done;
+	conf_t *conf = r10_bio->mddev->private;
 
-	bio_endio(bio,
-		test_bit(R10BIO_Uptodate, &r10_bio->state) ? 0 : -EIO);
+	if (bio->bi_phys_segments) {
+		unsigned long flags;
+		spin_lock_irqsave(&conf->device_lock, flags);
+		bio->bi_phys_segments--;
+		done = (bio->bi_phys_segments == 0);
+		spin_unlock_irqrestore(&conf->device_lock, flags);
+	} else
+		done = 1;
+	if (!test_bit(R10BIO_Uptodate, &r10_bio->state))
+		clear_bit(BIO_UPTODATE, &bio->bi_flags);
+	if (done) {
+		bio_endio(bio, 0);
+		/*
+		 * Wake up any possible resync thread that waits for the device
+		 * to go idle.
+		 */
+		allow_barrier(conf);
+	}
 	free_r10bio(r10_bio);
 }
 
@@ -244,6 +264,26 @@ static inline void update_head_pos(int slot, r10bio_t *r10_bio)
 		r10_bio->devs[slot].addr + (r10_bio->sectors);
 }
 
+/*
+ * Find the disk number which triggered given bio
+ */
+static int find_bio_disk(conf_t *conf, r10bio_t *r10_bio,
+			 struct bio *bio, int *slotp)
+{
+	int slot;
+
+	for (slot = 0; slot < conf->copies; slot++)
+		if (r10_bio->devs[slot].bio == bio)
+			break;
+
+	BUG_ON(slot == conf->copies);
+	update_head_pos(slot, r10_bio);
+
+	if (slotp)
+		*slotp = slot;
+	return r10_bio->devs[slot].devnum;
+}
+
 static void raid10_end_read_request(struct bio *bio, int error)
 {
 	int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
@@ -277,34 +317,45 @@ static void raid10_end_read_request(struct bio *bio, int error)
 		 * oops, read error - keep the refcount on the rdev
 		 */
 		char b[BDEVNAME_SIZE];
-		if (printk_ratelimit())
-			printk(KERN_ERR "md/raid10:%s: %s: rescheduling sector %llu\n",
-			       mdname(conf->mddev),
-			       bdevname(conf->mirrors[dev].rdev->bdev,b), (unsigned long long)r10_bio->sector);
+		printk_ratelimited(KERN_ERR
+				   "md/raid10:%s: %s: rescheduling sector %llu\n",
+				   mdname(conf->mddev),
+				   bdevname(conf->mirrors[dev].rdev->bdev, b),
+				   (unsigned long long)r10_bio->sector);
+		set_bit(R10BIO_ReadError, &r10_bio->state);
 		reschedule_retry(r10_bio);
 	}
 }
 
+static void close_write(r10bio_t *r10_bio)
+{
+	/* clear the bitmap if all writes complete successfully */
+	bitmap_endwrite(r10_bio->mddev->bitmap, r10_bio->sector,
+			r10_bio->sectors,
+			!test_bit(R10BIO_Degraded, &r10_bio->state),
+			0);
+	md_write_end(r10_bio->mddev);
+}
+
 static void raid10_end_write_request(struct bio *bio, int error)
 {
 	int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 	r10bio_t *r10_bio = bio->bi_private;
-	int slot, dev;
+	int dev;
+	int dec_rdev = 1;
 	conf_t *conf = r10_bio->mddev->private;
+	int slot;
 
-	for (slot = 0; slot < conf->copies; slot++)
-		if (r10_bio->devs[slot].bio == bio)
-			break;
-	dev = r10_bio->devs[slot].devnum;
+	dev = find_bio_disk(conf, r10_bio, bio, &slot);
 
 	/*
 	 * this branch is our 'one mirror IO has finished' event handler:
 	 */
 	if (!uptodate) {
-		md_error(r10_bio->mddev, conf->mirrors[dev].rdev);
-		/* an I/O failed, we can't clear the bitmap */
-		set_bit(R10BIO_Degraded, &r10_bio->state);
-	} else
+		set_bit(WriteErrorSeen,	&conf->mirrors[dev].rdev->flags);
+		set_bit(R10BIO_WriteError, &r10_bio->state);
+		dec_rdev = 0;
+	} else {
 		/*
 		 * Set R10BIO_Uptodate in our master bio, so that
 		 * we will return a good error code for to the higher
@@ -314,9 +365,22 @@ static void raid10_end_write_request(struct bio *bio, int error)
 		 * user-side. So if something waits for IO, then it will
 		 * wait for the 'master' bio.
 		 */
+		sector_t first_bad;
+		int bad_sectors;
+
 		set_bit(R10BIO_Uptodate, &r10_bio->state);
 
-	update_head_pos(slot, r10_bio);
+		/* Maybe we can clear some bad blocks. */
+		if (is_badblock(conf->mirrors[dev].rdev,
+				r10_bio->devs[slot].addr,
+				r10_bio->sectors,
+				&first_bad, &bad_sectors)) {
+			bio_put(bio);
+			r10_bio->devs[slot].bio = IO_MADE_GOOD;
+			dec_rdev = 0;
+			set_bit(R10BIO_MadeGood, &r10_bio->state);
+		}
+	}
 
 	/*
 	 *
@@ -324,16 +388,18 @@ static void raid10_end_write_request(struct bio *bio, int error)
 	 * already.
 	 */
 	if (atomic_dec_and_test(&r10_bio->remaining)) {
-		/* clear the bitmap if all writes complete successfully */
-		bitmap_endwrite(r10_bio->mddev->bitmap, r10_bio->sector,
-				r10_bio->sectors,
-				!test_bit(R10BIO_Degraded, &r10_bio->state),
-				0);
-		md_write_end(r10_bio->mddev);
-		raid_end_bio_io(r10_bio);
+		if (test_bit(R10BIO_WriteError, &r10_bio->state))
+			reschedule_retry(r10_bio);
+		else {
+			close_write(r10_bio);
+			if (test_bit(R10BIO_MadeGood, &r10_bio->state))
+				reschedule_retry(r10_bio);
+			else
+				raid_end_bio_io(r10_bio);
+		}
 	}
-
-	rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
+	if (dec_rdev)
+		rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
 }
 
 
@@ -484,11 +550,12 @@ static int raid10_mergeable_bvec(struct request_queue *q,
  * FIXME: possibly should rethink readbalancing and do it differently
  * depending on near_copies / far_copies geometry.
  */
-static int read_balance(conf_t *conf, r10bio_t *r10_bio)
+static int read_balance(conf_t *conf, r10bio_t *r10_bio, int *max_sectors)
 {
 	const sector_t this_sector = r10_bio->sector;
 	int disk, slot;
-	const int sectors = r10_bio->sectors;
+	int sectors = r10_bio->sectors;
+	int best_good_sectors;
 	sector_t new_distance, best_dist;
 	mdk_rdev_t *rdev;
 	int do_balance;
@@ -497,8 +564,10 @@ static int read_balance(conf_t *conf, r10bio_t *r10_bio)
 	raid10_find_phys(conf, r10_bio);
 	rcu_read_lock();
 retry:
+	sectors = r10_bio->sectors;
 	best_slot = -1;
 	best_dist = MaxSector;
+	best_good_sectors = 0;
 	do_balance = 1;
 	/*
 	 * Check if we can balance. We can balance on the whole
@@ -511,6 +580,10 @@ retry:
 		do_balance = 0;
 
 	for (slot = 0; slot < conf->copies ; slot++) {
+		sector_t first_bad;
+		int bad_sectors;
+		sector_t dev_sector;
+
 		if (r10_bio->devs[slot].bio == IO_BLOCKED)
 			continue;
 		disk = r10_bio->devs[slot].devnum;
@@ -520,6 +593,37 @@ retry:
 		if (!test_bit(In_sync, &rdev->flags))
 			continue;
 
+		dev_sector = r10_bio->devs[slot].addr;
+		if (is_badblock(rdev, dev_sector, sectors,
+				&first_bad, &bad_sectors)) {
+			if (best_dist < MaxSector)
+				/* Already have a better slot */
+				continue;
+			if (first_bad <= dev_sector) {
+				/* Cannot read here.  If this is the
+				 * 'primary' device, then we must not read
+				 * beyond 'bad_sectors' from another device.
+				 */
+				bad_sectors -= (dev_sector - first_bad);
+				if (!do_balance && sectors > bad_sectors)
+					sectors = bad_sectors;
+				if (best_good_sectors > sectors)
+					best_good_sectors = sectors;
+			} else {
+				sector_t good_sectors =
+					first_bad - dev_sector;
+				if (good_sectors > best_good_sectors) {
+					best_good_sectors = good_sectors;
+					best_slot = slot;
+				}
+				if (!do_balance)
+					/* Must read from here */
+					break;
+			}
+			continue;
+		} else
+			best_good_sectors = sectors;
+
 		if (!do_balance)
 			break;
 
@@ -561,6 +665,7 @@ retry:
 	} else
 		disk = -1;
 	rcu_read_unlock();
+	*max_sectors = best_good_sectors;
 
 	return disk;
 }
@@ -734,6 +839,8 @@ 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);
@@ -808,12 +915,26 @@ static int make_request(mddev_t *mddev, struct bio * bio)
 	r10_bio->sector = bio->bi_sector;
 	r10_bio->state = 0;
 
+	/* We might need to issue multiple reads to different
+	 * devices if there are bad blocks around, so we keep
+	 * track of the number of reads in bio->bi_phys_segments.
+	 * If this is 0, there is only one r10_bio and no locking
+	 * will be needed when the request completes.  If it is
+	 * non-zero, then it is the number of not-completed requests.
+	 */
+	bio->bi_phys_segments = 0;
+	clear_bit(BIO_SEG_VALID, &bio->bi_flags);
+
 	if (rw == READ) {
 		/*
 		 * read balancing logic:
 		 */
-		int disk = read_balance(conf, r10_bio);
-		int slot = r10_bio->read_slot;
+		int disk;
+		int slot;
+
+read_again:
+		disk = read_balance(conf, r10_bio, &max_sectors);
+		slot = r10_bio->read_slot;
 		if (disk < 0) {
 			raid_end_bio_io(r10_bio);
 			return 0;
@@ -821,6 +942,8 @@ static int make_request(mddev_t *mddev, struct bio * bio)
 		mirror = conf->mirrors + disk;
 
 		read_bio = bio_clone_mddev(bio, GFP_NOIO, mddev);
+		md_trim_bio(read_bio, r10_bio->sector - bio->bi_sector,
+			    max_sectors);
 
 		r10_bio->devs[slot].bio = read_bio;
 
@@ -831,7 +954,37 @@ static int make_request(mddev_t *mddev, struct bio * bio)
 		read_bio->bi_rw = READ | do_sync;
 		read_bio->bi_private = r10_bio;
 
-		generic_make_request(read_bio);
+		if (max_sectors < r10_bio->sectors) {
+			/* Could not read all from this device, so we will
+			 * need another r10_bio.
+			 */
+			sectors_handled = (r10_bio->sectors + max_sectors
+					   - bio->bi_sector);
+			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(&conf->device_lock);
+			/* Cannot call generic_make_request directly
+			 * as that will be queued in __generic_make_request
+			 * and subsequent mempool_alloc might block
+			 * waiting for it.  so hand bio over to raid10d.
+			 */
+			reschedule_retry(r10_bio);
+
+			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->state = 0;
+			r10_bio->mddev = mddev;
+			r10_bio->sector = bio->bi_sector + sectors_handled;
+			goto read_again;
+		} else
+			generic_make_request(read_bio);
 		return 0;
 	}
 
@@ -841,13 +994,22 @@ 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);
 
 	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);
@@ -856,13 +1018,55 @@ 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;
+		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();
 
@@ -882,8 +1086,22 @@ 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;
@@ -892,10 +1110,12 @@ 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;
@@ -920,6 +1140,21 @@ 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 r10_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;
@@ -949,6 +1184,30 @@ static void status(struct seq_file *seq, mddev_t *mddev)
 	seq_printf(seq, "]");
 }
 
+/* check if there are enough drives for
+ * every block to appear on atleast one.
+ * Don't consider the device numbered 'ignore'
+ * as we might be about to remove it.
+ */
+static int enough(conf_t *conf, int ignore)
+{
+	int first = 0;
+
+	do {
+		int n = conf->copies;
+		int cnt = 0;
+		while (n--) {
+			if (conf->mirrors[first].rdev &&
+			    first != ignore)
+				cnt++;
+			first = (first+1) % conf->raid_disks;
+		}
+		if (cnt == 0)
+			return 0;
+	} while (first != 0);
+	return 1;
+}
+
 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
 {
 	char b[BDEVNAME_SIZE];
@@ -961,13 +1220,9 @@ static void error(mddev_t *mddev, mdk_rdev_t *rdev)
 	 * else mark the drive as failed
 	 */
 	if (test_bit(In_sync, &rdev->flags)
-	    && conf->raid_disks-mddev->degraded == 1)
+	    && !enough(conf, rdev->raid_disk))
 		/*
 		 * Don't fail the drive, just return an IO error.
-		 * The test should really be more sophisticated than
-		 * "working_disks == 1", but it isn't critical, and
-		 * can wait until we do more sophisticated "is the drive
-		 * really dead" tests...
 		 */
 		return;
 	if (test_and_clear_bit(In_sync, &rdev->flags)) {
@@ -980,6 +1235,7 @@ static void error(mddev_t *mddev, mdk_rdev_t *rdev)
 		 */
 		set_bit(MD_RECOVERY_INTR, &mddev->recovery);
 	}
+	set_bit(Blocked, &rdev->flags);
 	set_bit(Faulty, &rdev->flags);
 	set_bit(MD_CHANGE_DEVS, &mddev->flags);
 	printk(KERN_ALERT
@@ -1022,27 +1278,6 @@ static void close_sync(conf_t *conf)
 	conf->r10buf_pool = NULL;
 }
 
-/* check if there are enough drives for
- * every block to appear on atleast one
- */
-static int enough(conf_t *conf)
-{
-	int first = 0;
-
-	do {
-		int n = conf->copies;
-		int cnt = 0;
-		while (n--) {
-			if (conf->mirrors[first].rdev)
-				cnt++;
-			first = (first+1) % conf->raid_disks;
-		}
-		if (cnt == 0)
-			return 0;
-	} while (first != 0);
-	return 1;
-}
-
 static int raid10_spare_active(mddev_t *mddev)
 {
 	int i;
@@ -1078,7 +1313,6 @@ static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
 	conf_t *conf = mddev->private;
 	int err = -EEXIST;
 	int mirror;
-	mirror_info_t *p;
 	int first = 0;
 	int last = conf->raid_disks - 1;
 
@@ -1087,44 +1321,47 @@ static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
 		 * very different from resync
 		 */
 		return -EBUSY;
-	if (!enough(conf))
+	if (!enough(conf, -1))
 		return -EINVAL;
 
 	if (rdev->raid_disk >= 0)
 		first = last = rdev->raid_disk;
 
-	if (rdev->saved_raid_disk >= 0 &&
-	    rdev->saved_raid_disk >= first &&
+	if (rdev->saved_raid_disk >= first &&
 	    conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
 		mirror = rdev->saved_raid_disk;
 	else
 		mirror = first;
-	for ( ; mirror <= last ; mirror++)
-		if ( !(p=conf->mirrors+mirror)->rdev) {
-
-			disk_stack_limits(mddev->gendisk, rdev->bdev,
-					  rdev->data_offset << 9);
-			/* as we don't honour merge_bvec_fn, we must
-			 * never risk violating it, so limit
-			 * ->max_segments to one lying with a single
-			 * page, as a one page request is never in
-			 * violation.
-			 */
-			if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
-				blk_queue_max_segments(mddev->queue, 1);
-				blk_queue_segment_boundary(mddev->queue,
-							   PAGE_CACHE_SIZE - 1);
-			}
+	for ( ; mirror <= last ; mirror++) {
+		mirror_info_t *p = &conf->mirrors[mirror];
+		if (p->recovery_disabled == mddev->recovery_disabled)
+			continue;
+		if (!p->rdev)
+			continue;
 
-			p->head_position = 0;
-			rdev->raid_disk = mirror;
-			err = 0;
-			if (rdev->saved_raid_disk != mirror)
-				conf->fullsync = 1;
-			rcu_assign_pointer(p->rdev, rdev);
-			break;
+		disk_stack_limits(mddev->gendisk, rdev->bdev,
+				  rdev->data_offset << 9);
+		/* as we don't honour merge_bvec_fn, we must
+		 * never risk violating it, so limit
+		 * ->max_segments to one lying with a single
+		 * page, as a one page request is never in
+		 * violation.
+		 */
+		if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
+			blk_queue_max_segments(mddev->queue, 1);
+			blk_queue_segment_boundary(mddev->queue,
+						   PAGE_CACHE_SIZE - 1);
 		}
 
+		p->head_position = 0;
+		rdev->raid_disk = mirror;
+		err = 0;
+		if (rdev->saved_raid_disk != mirror)
+			conf->fullsync = 1;
+		rcu_assign_pointer(p->rdev, rdev);
+		break;
+	}
+
 	md_integrity_add_rdev(rdev, mddev);
 	print_conf(conf);
 	return err;
@@ -1149,7 +1386,8 @@ static int raid10_remove_disk(mddev_t *mddev, int number)
 		 * is not possible.
 		 */
 		if (!test_bit(Faulty, &rdev->flags) &&
-		    enough(conf)) {
+		    mddev->recovery_disabled != p->recovery_disabled &&
+		    enough(conf, -1)) {
 			err = -EBUSY;
 			goto abort;
 		}
@@ -1174,24 +1412,18 @@ static void end_sync_read(struct bio *bio, int error)
 {
 	r10bio_t *r10_bio = bio->bi_private;
 	conf_t *conf = r10_bio->mddev->private;
-	int i,d;
+	int d;
 
-	for (i=0; i<conf->copies; i++)
-		if (r10_bio->devs[i].bio == bio)
-			break;
-	BUG_ON(i == conf->copies);
-	update_head_pos(i, r10_bio);
-	d = r10_bio->devs[i].devnum;
+	d = find_bio_disk(conf, r10_bio, bio, NULL);
 
 	if (test_bit(BIO_UPTODATE, &bio->bi_flags))
 		set_bit(R10BIO_Uptodate, &r10_bio->state);
-	else {
+	else
+		/* The write handler will notice the lack of
+		 * R10BIO_Uptodate and record any errors etc
+		 */
 		atomic_add(r10_bio->sectors,
 			   &conf->mirrors[d].rdev->corrected_errors);
-		if (!test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery))
-			md_error(r10_bio->mddev,
-				 conf->mirrors[d].rdev);
-	}
 
 	/* for reconstruct, we always reschedule after a read.
 	 * for resync, only after all reads
@@ -1206,40 +1438,60 @@ static void end_sync_read(struct bio *bio, int error)
 	}
 }
 
-static void end_sync_write(struct bio *bio, int error)
+static void end_sync_request(r10bio_t *r10_bio)
 {
-	int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
-	r10bio_t *r10_bio = bio->bi_private;
 	mddev_t *mddev = r10_bio->mddev;
-	conf_t *conf = mddev->private;
-	int i,d;
-
-	for (i = 0; i < conf->copies; i++)
-		if (r10_bio->devs[i].bio == bio)
-			break;
-	d = r10_bio->devs[i].devnum;
 
-	if (!uptodate)
-		md_error(mddev, conf->mirrors[d].rdev);
-
-	update_head_pos(i, r10_bio);
-
-	rdev_dec_pending(conf->mirrors[d].rdev, mddev);
 	while (atomic_dec_and_test(&r10_bio->remaining)) {
 		if (r10_bio->master_bio == NULL) {
 			/* the primary of several recovery bios */
 			sector_t s = r10_bio->sectors;
-			put_buf(r10_bio);
+			if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
+			    test_bit(R10BIO_WriteError, &r10_bio->state))
+				reschedule_retry(r10_bio);
+			else
+				put_buf(r10_bio);
 			md_done_sync(mddev, s, 1);
 			break;
 		} else {
 			r10bio_t *r10_bio2 = (r10bio_t *)r10_bio->master_bio;
-			put_buf(r10_bio);
+			if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
+			    test_bit(R10BIO_WriteError, &r10_bio->state))
+				reschedule_retry(r10_bio);
+			else
+				put_buf(r10_bio);
 			r10_bio = r10_bio2;
 		}
 	}
 }
 
+static void end_sync_write(struct bio *bio, int error)
+{
+	int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+	r10bio_t *r10_bio = bio->bi_private;
+	mddev_t *mddev = r10_bio->mddev;
+	conf_t *conf = mddev->private;
+	int d;
+	sector_t first_bad;
+	int bad_sectors;
+	int slot;
+
+	d = find_bio_disk(conf, r10_bio, bio, &slot);
+
+	if (!uptodate) {
+		set_bit(WriteErrorSeen, &conf->mirrors[d].rdev->flags);
+		set_bit(R10BIO_WriteError, &r10_bio->state);
+	} else if (is_badblock(conf->mirrors[d].rdev,
+			     r10_bio->devs[slot].addr,
+			     r10_bio->sectors,
+			     &first_bad, &bad_sectors))
+		set_bit(R10BIO_MadeGood, &r10_bio->state);
+
+	rdev_dec_pending(conf->mirrors[d].rdev, mddev);
+
+	end_sync_request(r10_bio);
+}
+
 /*
  * Note: sync and recover and handled very differently for raid10
  * This code is for resync.
@@ -1299,11 +1551,12 @@ static void sync_request_write(mddev_t *mddev, r10bio_t *r10_bio)
 			if (j == vcnt)
 				continue;
 			mddev->resync_mismatches += r10_bio->sectors;
+			if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
+				/* Don't fix anything. */
+				continue;
 		}
-		if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
-			/* Don't fix anything. */
-			continue;
-		/* Ok, we need to write this bio
+		/* Ok, we need to write this bio, either to correct an
+		 * inconsistency or to correct an unreadable block.
 		 * First we need to fixup bv_offset, bv_len and
 		 * bi_vecs, as the read request might have corrupted these
 		 */
@@ -1355,32 +1608,107 @@ done:
  * The second for writing.
  *
  */
+static void fix_recovery_read_error(r10bio_t *r10_bio)
+{
+	/* We got a read error during recovery.
+	 * We repeat the read in smaller page-sized sections.
+	 * If a read succeeds, write it to the new device or record
+	 * a bad block if we cannot.
+	 * If a read fails, record a bad block on both old and
+	 * new devices.
+	 */
+	mddev_t *mddev = r10_bio->mddev;
+	conf_t *conf = mddev->private;
+	struct bio *bio = r10_bio->devs[0].bio;
+	sector_t sect = 0;
+	int sectors = r10_bio->sectors;
+	int idx = 0;
+	int dr = r10_bio->devs[0].devnum;
+	int dw = r10_bio->devs[1].devnum;
+
+	while (sectors) {
+		int s = sectors;
+		mdk_rdev_t *rdev;
+		sector_t addr;
+		int ok;
+
+		if (s > (PAGE_SIZE>>9))
+			s = PAGE_SIZE >> 9;
+
+		rdev = conf->mirrors[dr].rdev;
+		addr = r10_bio->devs[0].addr + sect,
+		ok = sync_page_io(rdev,
+				  addr,
+				  s << 9,
+				  bio->bi_io_vec[idx].bv_page,
+				  READ, false);
+		if (ok) {
+			rdev = conf->mirrors[dw].rdev;
+			addr = r10_bio->devs[1].addr + sect;
+			ok = sync_page_io(rdev,
+					  addr,
+					  s << 9,
+					  bio->bi_io_vec[idx].bv_page,
+					  WRITE, false);
+			if (!ok)
+				set_bit(WriteErrorSeen, &rdev->flags);
+		}
+		if (!ok) {
+			/* We don't worry if we cannot set a bad block -
+			 * it really is bad so there is no loss in not
+			 * recording it yet
+			 */
+			rdev_set_badblocks(rdev, addr, s, 0);
+
+			if (rdev != conf->mirrors[dw].rdev) {
+				/* need bad block on destination too */
+				mdk_rdev_t *rdev2 = conf->mirrors[dw].rdev;
+				addr = r10_bio->devs[1].addr + sect;
+				ok = rdev_set_badblocks(rdev2, addr, s, 0);
+				if (!ok) {
+					/* just abort the recovery */
+					printk(KERN_NOTICE
+					       "md/raid10:%s: recovery aborted"
+					       " due to read error\n",
+					       mdname(mddev));
+
+					conf->mirrors[dw].recovery_disabled
+						= mddev->recovery_disabled;
+					set_bit(MD_RECOVERY_INTR,
+						&mddev->recovery);
+					break;
+				}
+			}
+		}
+
+		sectors -= s;
+		sect += s;
+		idx++;
+	}
+}
 
 static void recovery_request_write(mddev_t *mddev, r10bio_t *r10_bio)
 {
 	conf_t *conf = mddev->private;
-	int i, d;
-	struct bio *bio, *wbio;
+	int d;
+	struct bio *wbio;
 
+	if (!test_bit(R10BIO_Uptodate, &r10_bio->state)) {
+		fix_recovery_read_error(r10_bio);
+		end_sync_request(r10_bio);
+		return;
+	}
 
-	/* move the pages across to the second bio
+	/*
+	 * share the pages with the first bio
 	 * and submit the write request
 	 */
-	bio = r10_bio->devs[0].bio;
 	wbio = r10_bio->devs[1].bio;
-	for (i=0; i < wbio->bi_vcnt; i++) {
-		struct page *p = bio->bi_io_vec[i].bv_page;
-		bio->bi_io_vec[i].bv_page = wbio->bi_io_vec[i].bv_page;
-		wbio->bi_io_vec[i].bv_page = p;
-	}
 	d = r10_bio->devs[1].devnum;
 
 	atomic_inc(&conf->mirrors[d].rdev->nr_pending);
 	md_sync_acct(conf->mirrors[d].rdev->bdev, wbio->bi_size >> 9);
-	if (test_bit(R10BIO_Uptodate, &r10_bio->state))
-		generic_make_request(wbio);
-	else
-		bio_endio(wbio, -EIO);
+	generic_make_request(wbio);
 }
 
 
@@ -1421,6 +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:
  *
@@ -1476,10 +1824,15 @@ static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
 
 		rcu_read_lock();
 		do {
+			sector_t first_bad;
+			int bad_sectors;
+
 			d = r10_bio->devs[sl].devnum;
 			rdev = rcu_dereference(conf->mirrors[d].rdev);
 			if (rdev &&
-			    test_bit(In_sync, &rdev->flags)) {
+			    test_bit(In_sync, &rdev->flags) &&
+			    is_badblock(rdev, r10_bio->devs[sl].addr + sect, s,
+					&first_bad, &bad_sectors) == 0) {
 				atomic_inc(&rdev->nr_pending);
 				rcu_read_unlock();
 				success = sync_page_io(rdev,
@@ -1499,9 +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;
 		}
 
@@ -1516,80 +1879,82 @@ static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
 			sl--;
 			d = r10_bio->devs[sl].devnum;
 			rdev = rcu_dereference(conf->mirrors[d].rdev);
-			if (rdev &&
-			    test_bit(In_sync, &rdev->flags)) {
-				atomic_inc(&rdev->nr_pending);
-				rcu_read_unlock();
-				atomic_add(s, &rdev->corrected_errors);
-				if (sync_page_io(rdev,
-						 r10_bio->devs[sl].addr +
-						 sect,
-						 s<<9, conf->tmppage, WRITE, false)
-				    == 0) {
-					/* Well, this device is dead */
-					printk(KERN_NOTICE
-					       "md/raid10:%s: read correction "
-					       "write failed"
-					       " (%d sectors at %llu on %s)\n",
-					       mdname(mddev), s,
-					       (unsigned long long)(
-						       sect + rdev->data_offset),
-					       bdevname(rdev->bdev, b));
-					printk(KERN_NOTICE "md/raid10:%s: %s: failing "
-					       "drive\n",
-					       mdname(mddev),
-					       bdevname(rdev->bdev, b));
-					md_error(mddev, rdev);
-				}
-				rdev_dec_pending(rdev, mddev);
-				rcu_read_lock();
+			if (!rdev ||
+			    !test_bit(In_sync, &rdev->flags))
+				continue;
+
+			atomic_inc(&rdev->nr_pending);
+			rcu_read_unlock();
+			if (r10_sync_page_io(rdev,
+					     r10_bio->devs[sl].addr +
+					     sect,
+					     s<<9, conf->tmppage, WRITE)
+			    == 0) {
+				/* Well, this device is dead */
+				printk(KERN_NOTICE
+				       "md/raid10:%s: read correction "
+				       "write failed"
+				       " (%d sectors at %llu on %s)\n",
+				       mdname(mddev), s,
+				       (unsigned long long)(
+					       sect + rdev->data_offset),
+				       bdevname(rdev->bdev, b));
+				printk(KERN_NOTICE "md/raid10:%s: %s: failing "
+				       "drive\n",
+				       mdname(mddev),
+				       bdevname(rdev->bdev, b));
 			}
+			rdev_dec_pending(rdev, mddev);
+			rcu_read_lock();
 		}
 		sl = start;
 		while (sl != r10_bio->read_slot) {
+			char b[BDEVNAME_SIZE];
 
 			if (sl==0)
 				sl = conf->copies;
 			sl--;
 			d = r10_bio->devs[sl].devnum;
 			rdev = rcu_dereference(conf->mirrors[d].rdev);
-			if (rdev &&
-			    test_bit(In_sync, &rdev->flags)) {
-				char b[BDEVNAME_SIZE];
-				atomic_inc(&rdev->nr_pending);
-				rcu_read_unlock();
-				if (sync_page_io(rdev,
-						 r10_bio->devs[sl].addr +
-						 sect,
-						 s<<9, conf->tmppage,
-						 READ, false) == 0) {
-					/* Well, this device is dead */
-					printk(KERN_NOTICE
-					       "md/raid10:%s: unable to read back "
-					       "corrected sectors"
-					       " (%d sectors at %llu on %s)\n",
-					       mdname(mddev), s,
-					       (unsigned long long)(
-						       sect + rdev->data_offset),
-					       bdevname(rdev->bdev, b));
-					printk(KERN_NOTICE "md/raid10:%s: %s: failing drive\n",
-					       mdname(mddev),
-					       bdevname(rdev->bdev, b));
-
-					md_error(mddev, rdev);
-				} else {
-					printk(KERN_INFO
-					       "md/raid10:%s: read error corrected"
-					       " (%d sectors at %llu on %s)\n",
-					       mdname(mddev), s,
-					       (unsigned long long)(
-						       sect + rdev->data_offset),
-					       bdevname(rdev->bdev, b));
-				}
+			if (!rdev ||
+			    !test_bit(In_sync, &rdev->flags))
+				continue;
 
-				rdev_dec_pending(rdev, mddev);
-				rcu_read_lock();
+			atomic_inc(&rdev->nr_pending);
+			rcu_read_unlock();
+			switch (r10_sync_page_io(rdev,
+					     r10_bio->devs[sl].addr +
+					     sect,
+					     s<<9, conf->tmppage,
+						 READ)) {
+			case 0:
+				/* Well, this device is dead */
+				printk(KERN_NOTICE
+				       "md/raid10:%s: unable to read back "
+				       "corrected sectors"
+				       " (%d sectors at %llu on %s)\n",
+				       mdname(mddev), s,
+				       (unsigned long long)(
+					       sect + rdev->data_offset),
+				       bdevname(rdev->bdev, b));
+				printk(KERN_NOTICE "md/raid10:%s: %s: failing "
+				       "drive\n",
+				       mdname(mddev),
+				       bdevname(rdev->bdev, b));
+				break;
+			case 1:
+				printk(KERN_INFO
+				       "md/raid10:%s: read error corrected"
+				       " (%d sectors at %llu on %s)\n",
+				       mdname(mddev), s,
+				       (unsigned long long)(
+					       sect + rdev->data_offset),
+				       bdevname(rdev->bdev, b));
+				atomic_add(s, &rdev->corrected_errors);
 			}
+
+			rdev_dec_pending(rdev, mddev);
+			rcu_read_lock();
 		}
 		rcu_read_unlock();
 
@@ -1598,21 +1963,254 @@ static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
 	}
 }
 
+static void bi_complete(struct bio *bio, int error)
+{
+	complete((struct completion *)bio->bi_private);
+}
+
+static int submit_bio_wait(int rw, struct bio *bio)
+{
+	struct completion event;
+	rw |= REQ_SYNC;
+
+	init_completion(&event);
+	bio->bi_private = &event;
+	bio->bi_end_io = bi_complete;
+	submit_bio(rw, bio);
+	wait_for_completion(&event);
+
+	return test_bit(BIO_UPTODATE, &bio->bi_flags);
+}
+
+static int narrow_write_error(r10bio_t *r10_bio, int i)
+{
+	struct bio *bio = r10_bio->master_bio;
+	mddev_t *mddev = r10_bio->mddev;
+	conf_t *conf = mddev->private;
+	mdk_rdev_t *rdev = conf->mirrors[r10_bio->devs[i].devnum].rdev;
+	/* bio has the data to be written to slot 'i' where
+	 * we just recently had a write error.
+	 * We repeatedly clone the bio and trim down to one block,
+	 * then try the write.  Where the write fails we record
+	 * a bad block.
+	 * It is conceivable that the bio doesn't exactly align with
+	 * blocks.  We must handle this.
+	 *
+	 * We currently own a reference to the rdev.
+	 */
+
+	int block_sectors;
+	sector_t sector;
+	int sectors;
+	int sect_to_write = r10_bio->sectors;
+	int ok = 1;
+
+	if (rdev->badblocks.shift < 0)
+		return 0;
+
+	block_sectors = 1 << rdev->badblocks.shift;
+	sector = r10_bio->sector;
+	sectors = ((r10_bio->sector + block_sectors)
+		   & ~(sector_t)(block_sectors - 1))
+		- sector;
+
+	while (sect_to_write) {
+		struct bio *wbio;
+		if (sectors > sect_to_write)
+			sectors = sect_to_write;
+		/* Write at 'sector' for 'sectors' */
+		wbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
+		md_trim_bio(wbio, sector - bio->bi_sector, sectors);
+		wbio->bi_sector = (r10_bio->devs[i].addr+
+				   rdev->data_offset+
+				   (sector - r10_bio->sector));
+		wbio->bi_bdev = rdev->bdev;
+		if (submit_bio_wait(WRITE, wbio) == 0)
+			/* Failure! */
+			ok = rdev_set_badblocks(rdev, sector,
+						sectors, 0)
+				&& ok;
+
+		bio_put(wbio);
+		sect_to_write -= sectors;
+		sector += sectors;
+		sectors = block_sectors;
+	}
+	return ok;
+}
+
+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;
+	int max_sectors;
+
+	/* 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;
+	bdevname(bio->bi_bdev, b);
+	r10_bio->devs[slot].bio =
+		mddev->ro ? IO_BLOCKED : NULL;
+read_more:
+	mirror = read_balance(conf, r10_bio, &max_sectors);
+	if (mirror == -1) {
+		printk(KERN_ALERT "md/raid10:%s: %s: unrecoverable I/O"
+		       " read error for block %llu\n",
+		       mdname(mddev), 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);
+	if (bio)
+		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);
+	md_trim_bio(bio,
+		    r10_bio->sector - bio->bi_sector,
+		    max_sectors);
+	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;
+	if (max_sectors < r10_bio->sectors) {
+		/* Drat - have to split this up more */
+		struct bio *mbio = r10_bio->master_bio;
+		int sectors_handled =
+			r10_bio->sector + max_sectors
+			- mbio->bi_sector;
+		r10_bio->sectors = max_sectors;
+		spin_lock_irq(&conf->device_lock);
+		if (mbio->bi_phys_segments == 0)
+			mbio->bi_phys_segments = 2;
+		else
+			mbio->bi_phys_segments++;
+		spin_unlock_irq(&conf->device_lock);
+		generic_make_request(bio);
+		bio = NULL;
+
+		r10_bio = mempool_alloc(conf->r10bio_pool,
+					GFP_NOIO);
+		r10_bio->master_bio = mbio;
+		r10_bio->sectors = (mbio->bi_size >> 9)
+			- sectors_handled;
+		r10_bio->state = 0;
+		set_bit(R10BIO_ReadError,
+			&r10_bio->state);
+		r10_bio->mddev = mddev;
+		r10_bio->sector = mbio->bi_sector
+			+ sectors_handled;
+
+		goto read_more;
+	} else
+		generic_make_request(bio);
+}
+
+static void handle_write_completed(conf_t *conf, r10bio_t *r10_bio)
+{
+	/* Some sort of write request has finished and it
+	 * succeeded in writing where we thought there was a
+	 * bad block.  So forget the bad block.
+	 * Or possibly if failed and we need to record
+	 * a bad block.
+	 */
+	int m;
+	mdk_rdev_t *rdev;
+
+	if (test_bit(R10BIO_IsSync, &r10_bio->state) ||
+	    test_bit(R10BIO_IsRecover, &r10_bio->state)) {
+		for (m = 0; m < conf->copies; m++) {
+			int dev = r10_bio->devs[m].devnum;
+			rdev = conf->mirrors[dev].rdev;
+			if (r10_bio->devs[m].bio == NULL)
+				continue;
+			if (test_bit(BIO_UPTODATE,
+				     &r10_bio->devs[m].bio->bi_flags)) {
+				rdev_clear_badblocks(
+					rdev,
+					r10_bio->devs[m].addr,
+					r10_bio->sectors);
+			} else {
+				if (!rdev_set_badblocks(
+					    rdev,
+					    r10_bio->devs[m].addr,
+					    r10_bio->sectors, 0))
+					md_error(conf->mddev, rdev);
+			}
+		}
+		put_buf(r10_bio);
+	} else {
+		for (m = 0; m < conf->copies; m++) {
+			int dev = r10_bio->devs[m].devnum;
+			struct bio *bio = r10_bio->devs[m].bio;
+			rdev = conf->mirrors[dev].rdev;
+			if (bio == IO_MADE_GOOD) {
+				rdev_clear_badblocks(
+					rdev,
+					r10_bio->devs[m].addr,
+					r10_bio->sectors);
+				rdev_dec_pending(rdev, conf->mddev);
+			} else if (bio != NULL &&
+				   !test_bit(BIO_UPTODATE, &bio->bi_flags)) {
+				if (!narrow_write_error(r10_bio, m)) {
+					md_error(conf->mddev, rdev);
+					set_bit(R10BIO_Degraded,
+						&r10_bio->state);
+				}
+				rdev_dec_pending(rdev, conf->mddev);
+			}
+		}
+		if (test_bit(R10BIO_WriteError,
+			     &r10_bio->state))
+			close_write(r10_bio);
+		raid_end_bio_io(r10_bio);
+	}
+}
+
 static void raid10d(mddev_t *mddev)
 {
 	r10bio_t *r10_bio;
-	struct bio *bio;
 	unsigned long flags;
 	conf_t *conf = mddev->private;
 	struct list_head *head = &conf->retry_list;
-	mdk_rdev_t *rdev;
 	struct blk_plug plug;
 
 	md_check_recovery(mddev);
 
 	blk_start_plug(&plug);
 	for (;;) {
-		char b[BDEVNAME_SIZE];
 
 		flush_pending_writes(conf);
 
@@ -1628,64 +2226,26 @@ static void raid10d(mddev_t *mddev)
 
 		mddev = r10_bio->mddev;
 		conf = mddev->private;
-		if (test_bit(R10BIO_IsSync, &r10_bio->state))
+		if (test_bit(R10BIO_MadeGood, &r10_bio->state) ||
+		    test_bit(R10BIO_WriteError, &r10_bio->state))
+			handle_write_completed(conf, r10_bio);
+		else if (test_bit(R10BIO_IsSync, &r10_bio->state))
 			sync_request_write(mddev, r10_bio);
 		else if (test_bit(R10BIO_IsRecover, &r10_bio->state))
 			recovery_request_write(mddev, r10_bio);
+		else if (test_bit(R10BIO_ReadError, &r10_bio->state))
+			handle_read_error(mddev, r10_bio);
 		else {
-			int slot = r10_bio->read_slot;
-			int mirror = r10_bio->devs[slot].devnum;
-			/* 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.
+			/* just a partial read to be scheduled from a
+			 * separate context
 			 */
-			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);
-			} else {
-				const unsigned long do_sync = (r10_bio->master_bio->bi_rw & REQ_SYNC);
-				bio_put(bio);
-				slot = r10_bio->read_slot;
-				rdev = conf->mirrors[mirror].rdev;
-				if (printk_ratelimit())
-					printk(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);
-			}
+			int slot = r10_bio->read_slot;
+			generic_make_request(r10_bio->devs[slot].bio);
 		}
+
 		cond_resched();
+		if (mddev->flags & ~(1<<MD_CHANGE_PENDING))
+			md_check_recovery(mddev);
 	}
 	blk_finish_plug(&plug);
 }
@@ -1746,7 +2306,6 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr,
 	int i;
 	int max_sync;
 	sector_t sync_blocks;
-
 	sector_t sectors_skipped = 0;
 	int chunks_skipped = 0;
 
@@ -1828,7 +2387,7 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr,
 	max_sync = RESYNC_PAGES << (PAGE_SHIFT-9);
 	if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
 		/* recovery... the complicated one */
-		int j, k;
+		int j;
 		r10_bio = NULL;
 
 		for (i=0 ; i<conf->raid_disks; i++) {
@@ -1836,6 +2395,7 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr,
 			r10bio_t *rb2;
 			sector_t sect;
 			int must_sync;
+			int any_working;
 
 			if (conf->mirrors[i].rdev == NULL ||
 			    test_bit(In_sync, &conf->mirrors[i].rdev->flags)) 
@@ -1887,19 +2447,42 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr,
 			must_sync = bitmap_start_sync(mddev->bitmap, sect,
 						      &sync_blocks, still_degraded);
 
+			any_working = 0;
 			for (j=0; j<conf->copies;j++) {
+				int k;
 				int d = r10_bio->devs[j].devnum;
+				sector_t from_addr, to_addr;
+				mdk_rdev_t *rdev;
+				sector_t sector, first_bad;
+				int bad_sectors;
 				if (!conf->mirrors[d].rdev ||
 				    !test_bit(In_sync, &conf->mirrors[d].rdev->flags))
 					continue;
 				/* This is where we read from */
+				any_working = 1;
+				rdev = conf->mirrors[d].rdev;
+				sector = r10_bio->devs[j].addr;
+
+				if (is_badblock(rdev, sector, max_sync,
+						&first_bad, &bad_sectors)) {
+					if (first_bad > sector)
+						max_sync = first_bad - sector;
+					else {
+						bad_sectors -= (sector
+								- first_bad);
+						if (max_sync > bad_sectors)
+							max_sync = bad_sectors;
+						continue;
+					}
+				}
 				bio = r10_bio->devs[0].bio;
 				bio->bi_next = biolist;
 				biolist = bio;
 				bio->bi_private = r10_bio;
 				bio->bi_end_io = end_sync_read;
 				bio->bi_rw = READ;
-				bio->bi_sector = r10_bio->devs[j].addr +
+				from_addr = r10_bio->devs[j].addr;
+				bio->bi_sector = from_addr +
 					conf->mirrors[d].rdev->data_offset;
 				bio->bi_bdev = conf->mirrors[d].rdev->bdev;
 				atomic_inc(&conf->mirrors[d].rdev->nr_pending);
@@ -1916,26 +2499,48 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr,
 				bio->bi_private = r10_bio;
 				bio->bi_end_io = end_sync_write;
 				bio->bi_rw = WRITE;
-				bio->bi_sector = r10_bio->devs[k].addr +
+				to_addr = r10_bio->devs[k].addr;
+				bio->bi_sector = to_addr +
 					conf->mirrors[i].rdev->data_offset;
 				bio->bi_bdev = conf->mirrors[i].rdev->bdev;
 
 				r10_bio->devs[0].devnum = d;
+				r10_bio->devs[0].addr = from_addr;
 				r10_bio->devs[1].devnum = i;
+				r10_bio->devs[1].addr = to_addr;
 
 				break;
 			}
 			if (j == conf->copies) {
-				/* Cannot recover, so abort the recovery */
+				/* Cannot recover, so abort the recovery or
+				 * record a bad block */
 				put_buf(r10_bio);
 				if (rb2)
 					atomic_dec(&rb2->remaining);
 				r10_bio = rb2;
-				if (!test_and_set_bit(MD_RECOVERY_INTR,
-						      &mddev->recovery))
-					printk(KERN_INFO "md/raid10:%s: insufficient "
-					       "working devices for recovery.\n",
-					       mdname(mddev));
+				if (any_working) {
+					/* problem is that there are bad blocks
+					 * on other device(s)
+					 */
+					int k;
+					for (k = 0; k < conf->copies; k++)
+						if (r10_bio->devs[k].devnum == i)
+							break;
+					if (!rdev_set_badblocks(
+						    conf->mirrors[i].rdev,
+						    r10_bio->devs[k].addr,
+						    max_sync, 0))
+						any_working = 0;
+				}
+				if (!any_working)  {
+					if (!test_and_set_bit(MD_RECOVERY_INTR,
+							      &mddev->recovery))
+						printk(KERN_INFO "md/raid10:%s: insufficient "
+						       "working devices for recovery.\n",
+						       mdname(mddev));
+					conf->mirrors[i].recovery_disabled
+						= mddev->recovery_disabled;
+				}
 				break;
 			}
 		}
@@ -1979,12 +2584,28 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr,
 
 		for (i=0; i<conf->copies; i++) {
 			int d = r10_bio->devs[i].devnum;
+			sector_t first_bad, sector;
+			int bad_sectors;
+
 			bio = r10_bio->devs[i].bio;
 			bio->bi_end_io = NULL;
 			clear_bit(BIO_UPTODATE, &bio->bi_flags);
 			if (conf->mirrors[d].rdev == NULL ||
 			    test_bit(Faulty, &conf->mirrors[d].rdev->flags))
 				continue;
+			sector = r10_bio->devs[i].addr;
+			if (is_badblock(conf->mirrors[d].rdev,
+					sector, max_sync,
+					&first_bad, &bad_sectors)) {
+				if (first_bad > sector)
+					max_sync = first_bad - sector;
+				else {
+					bad_sectors -= (sector - first_bad);
+					if (max_sync > bad_sectors)
+						max_sync = max_sync;
+					continue;
+				}
+			}
 			atomic_inc(&conf->mirrors[d].rdev->nr_pending);
 			atomic_inc(&r10_bio->remaining);
 			bio->bi_next = biolist;
@@ -1992,7 +2613,7 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr,
 			bio->bi_private = r10_bio;
 			bio->bi_end_io = end_sync_read;
 			bio->bi_rw = READ;
-			bio->bi_sector = r10_bio->devs[i].addr +
+			bio->bi_sector = sector +
 				conf->mirrors[d].rdev->data_offset;
 			bio->bi_bdev = conf->mirrors[d].rdev->bdev;
 			count++;
@@ -2079,7 +2700,8 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr,
 	return sectors_skipped + nr_sectors;
  giveup:
 	/* There is nowhere to write, so all non-sync
-	 * drives must be failed, so try the next chunk...
+	 * drives must be failed or in resync, all drives
+	 * have a bad block, so try the next chunk...
 	 */
 	if (sector_nr + max_sync < max_sector)
 		max_sector = sector_nr + max_sync;
@@ -2249,6 +2871,7 @@ static int run(mddev_t *mddev)
 				 (conf->raid_disks / conf->near_copies));
 
 	list_for_each_entry(rdev, &mddev->disks, same_set) {
+
 		disk_idx = rdev->raid_disk;
 		if (disk_idx >= conf->raid_disks
 		    || disk_idx < 0)
@@ -2271,7 +2894,7 @@ static int run(mddev_t *mddev)
 		disk->head_position = 0;
 	}
 	/* need to check that every block has at least one working mirror */
-	if (!enough(conf)) {
+	if (!enough(conf, -1)) {
 		printk(KERN_ERR "md/raid10:%s: not enough operational mirrors.\n",
 		       mdname(mddev));
 		goto out_free_conf;