Merge branch 'md-next' into md-linus

1 files changed, 306 insertions, 430 deletions

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 28ec3a93acee..6b86a0032cf8 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -110,6 +110,24 @@ static void end_reshape(struct r10conf *conf);
 #define raid10_log(md, fmt, args...)				\
 	do { if ((md)->queue) blk_add_trace_msg((md)->queue, "raid10 " fmt, ##args); } while (0)
 
+/*
+ * 'strct resync_pages' stores actual pages used for doing the resync
+ *  IO, and it is per-bio, so make .bi_private points to it.
+ */
+static inline struct resync_pages *get_resync_pages(struct bio *bio)
+{
+	return bio->bi_private;
+}
+
+/*
+ * for resync bio, r10bio pointer can be retrieved from the per-bio
+ * 'struct resync_pages'.
+ */
+static inline struct r10bio *get_resync_r10bio(struct bio *bio)
+{
+	return get_resync_pages(bio)->raid_bio;
+}
+
 static void * r10bio_pool_alloc(gfp_t gfp_flags, void *data)
 {
 	struct r10conf *conf = data;
@@ -125,9 +143,6 @@ static void r10bio_pool_free(void *r10_bio, void *data)
 	kfree(r10_bio);
 }
 
-/* Maximum size of each resync request */
-#define RESYNC_BLOCK_SIZE (64*1024)
-#define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
 /* amount of memory to reserve for resync requests */
 #define RESYNC_WINDOW (1024*1024)
 /* maximum number of concurrent requests, memory permitting */
@@ -143,11 +158,11 @@ static void r10bio_pool_free(void *r10_bio, void *data)
 static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
 {
 	struct r10conf *conf = data;
-	struct page *page;
 	struct r10bio *r10_bio;
 	struct bio *bio;
-	int i, j;
-	int nalloc;
+	int j;
+	int nalloc, nalloc_rp;
+	struct resync_pages *rps;
 
 	r10_bio = r10bio_pool_alloc(gfp_flags, conf);
 	if (!r10_bio)
@@ -159,6 +174,15 @@ static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
 	else
 		nalloc = 2; /* recovery */
 
+	/* allocate once for all bios */
+	if (!conf->have_replacement)
+		nalloc_rp = nalloc;
+	else
+		nalloc_rp = nalloc * 2;
+	rps = kmalloc(sizeof(struct resync_pages) * nalloc_rp, gfp_flags);
+	if (!rps)
+		goto out_free_r10bio;
+
 	/*
 	 * Allocate bios.
 	 */
@@ -178,36 +202,40 @@ static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
 	 * Allocate RESYNC_PAGES data pages and attach them
 	 * where needed.
 	 */
-	for (j = 0 ; j < nalloc; j++) {
+	for (j = 0; j < nalloc; j++) {
 		struct bio *rbio = r10_bio->devs[j].repl_bio;
+		struct resync_pages *rp, *rp_repl;
+
+		rp = &rps[j];
+		if (rbio)
+			rp_repl = &rps[nalloc + j];
+
 		bio = r10_bio->devs[j].bio;
-		for (i = 0; i < RESYNC_PAGES; i++) {
-			if (j > 0 && !test_bit(MD_RECOVERY_SYNC,
-					       &conf->mddev->recovery)) {
-				/* we can share bv_page's during recovery
-				 * and reshape */
-				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))
+
+		if (!j || test_bit(MD_RECOVERY_SYNC,
+				   &conf->mddev->recovery)) {
+			if (resync_alloc_pages(rp, gfp_flags))
 				goto out_free_pages;
+		} else {
+			memcpy(rp, &rps[0], sizeof(*rp));
+			resync_get_all_pages(rp);
+		}
 
-			bio->bi_io_vec[i].bv_page = page;
-			if (rbio)
-				rbio->bi_io_vec[i].bv_page = page;
+		rp->idx = 0;
+		rp->raid_bio = r10_bio;
+		bio->bi_private = rp;
+		if (rbio) {
+			memcpy(rp_repl, rp, sizeof(*rp));
+			rbio->bi_private = rp_repl;
 		}
 	}
 
 	return r10_bio;
 
 out_free_pages:
-	for ( ; i > 0 ; i--)
-		safe_put_page(bio->bi_io_vec[i-1].bv_page);
-	while (j--)
-		for (i = 0; i < RESYNC_PAGES ; i++)
-			safe_put_page(r10_bio->devs[j].bio->bi_io_vec[i].bv_page);
+	while (--j >= 0)
+		resync_free_pages(&rps[j * 2]);
+
 	j = 0;
 out_free_bio:
 	for ( ; j < nalloc; j++) {
@@ -216,30 +244,34 @@ out_free_bio:
 		if (r10_bio->devs[j].repl_bio)
 			bio_put(r10_bio->devs[j].repl_bio);
 	}
+	kfree(rps);
+out_free_r10bio:
 	r10bio_pool_free(r10_bio, conf);
 	return NULL;
 }
 
 static void r10buf_pool_free(void *__r10_bio, void *data)
 {
-	int i;
 	struct r10conf *conf = data;
 	struct r10bio *r10bio = __r10_bio;
 	int j;
+	struct resync_pages *rp = NULL;
 
-	for (j=0; j < conf->copies; j++) {
+	for (j = conf->copies; j--; ) {
 		struct bio *bio = r10bio->devs[j].bio;
-		if (bio) {
-			for (i = 0; i < RESYNC_PAGES; i++) {
-				safe_put_page(bio->bi_io_vec[i].bv_page);
-				bio->bi_io_vec[i].bv_page = NULL;
-			}
-			bio_put(bio);
-		}
+
+		rp = get_resync_pages(bio);
+		resync_free_pages(rp);
+		bio_put(bio);
+
 		bio = r10bio->devs[j].repl_bio;
 		if (bio)
 			bio_put(bio);
 	}
+
+	/* resync pages array stored in the 1st bio's .bi_private */
+	kfree(rp);
+
 	r10bio_pool_free(r10bio, conf);
 }
 
@@ -301,27 +333,18 @@ static void reschedule_retry(struct r10bio *r10_bio)
 static void raid_end_bio_io(struct r10bio *r10_bio)
 {
 	struct bio *bio = r10_bio->master_bio;
-	int done;
 	struct r10conf *conf = r10_bio->mddev->private;
 
-	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))
 		bio->bi_error = -EIO;
-	if (done) {
-		bio_endio(bio);
-		/*
-		 * Wake up any possible resync thread that waits for the device
-		 * to go idle.
-		 */
-		allow_barrier(conf);
-	}
+
+	bio_endio(bio);
+	/*
+	 * Wake up any possible resync thread that waits for the device
+	 * to go idle.
+	 */
+	allow_barrier(conf);
+
 	free_r10bio(r10_bio);
 }
 
@@ -1095,12 +1118,41 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
 	struct bio *read_bio;
 	const int op = bio_op(bio);
 	const unsigned long do_sync = (bio->bi_opf & REQ_SYNC);
-	int sectors_handled;
 	int max_sectors;
 	sector_t sectors;
 	struct md_rdev *rdev;
-	int slot;
+	char b[BDEVNAME_SIZE];
+	int slot = r10_bio->read_slot;
+	struct md_rdev *err_rdev = NULL;
+	gfp_t gfp = GFP_NOIO;
 
+	if (r10_bio->devs[slot].rdev) {
+		/*
+		 * This is an error retry, but we cannot
+		 * safely dereference the rdev in the r10_bio,
+		 * we must use the one in conf.
+		 * If it has already been disconnected (unlikely)
+		 * we lose the device name in error messages.
+		 */
+		int disk;
+		/*
+		 * As we are blocking raid10, it is a little safer to
+		 * use __GFP_HIGH.
+		 */
+		gfp = GFP_NOIO | __GFP_HIGH;
+
+		rcu_read_lock();
+		disk = r10_bio->devs[slot].devnum;
+		err_rdev = rcu_dereference(conf->mirrors[disk].rdev);
+		if (err_rdev)
+			bdevname(err_rdev->bdev, b);
+		else {
+			strcpy(b, "???");
+			/* This never gets dereferenced */
+			err_rdev = r10_bio->devs[slot].rdev;
+		}
+		rcu_read_unlock();
+	}
 	/*
 	 * Register the new request and wait if the reconstruction
 	 * thread has put up a bar for new requests.
@@ -1108,7 +1160,7 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
 	 */
 	wait_barrier(conf);
 
-	sectors = bio_sectors(bio);
+	sectors = r10_bio->sectors;
 	while (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
 	    bio->bi_iter.bi_sector < conf->reshape_progress &&
 	    bio->bi_iter.bi_sector + sectors > conf->reshape_progress) {
@@ -1125,17 +1177,33 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
 		wait_barrier(conf);
 	}
 
-read_again:
 	rdev = read_balance(conf, r10_bio, &max_sectors);
 	if (!rdev) {
+		if (err_rdev) {
+			pr_crit_ratelimited("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);
 		return;
 	}
+	if (err_rdev)
+		pr_err_ratelimited("md/raid10:%s: %s: redirecting sector %llu to another mirror\n",
+				   mdname(mddev),
+				   bdevname(rdev->bdev, b),
+				   (unsigned long long)r10_bio->sector);
+	if (max_sectors < bio_sectors(bio)) {
+		struct bio *split = bio_split(bio, max_sectors,
+					      gfp, conf->bio_split);
+		bio_chain(split, bio);
+		generic_make_request(bio);
+		bio = split;
+		r10_bio->master_bio = bio;
+		r10_bio->sectors = max_sectors;
+	}
 	slot = r10_bio->read_slot;
 
-	read_bio = bio_clone_fast(bio, GFP_NOIO, mddev->bio_set);
-	bio_trim(read_bio, r10_bio->sector - bio->bi_iter.bi_sector,
-		 max_sectors);
+	read_bio = bio_clone_fast(bio, gfp, mddev->bio_set);
 
 	r10_bio->devs[slot].bio = read_bio;
 	r10_bio->devs[slot].rdev = rdev;
@@ -1154,55 +1222,86 @@ read_again:
 	        trace_block_bio_remap(bdev_get_queue(read_bio->bi_bdev),
 	                              read_bio, disk_devt(mddev->gendisk),
 	                              r10_bio->sector);
-	if (max_sectors < r10_bio->sectors) {
-		/*
-		 * Could not read all from this device, so we will need another
-		 * r10_bio.
-		 */
-		sectors_handled = (r10_bio->sector + max_sectors
-				   - bio->bi_iter.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_irq(&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_sectors(bio) - sectors_handled;
-		r10_bio->state = 0;
-		r10_bio->mddev = mddev;
-		r10_bio->sector = bio->bi_iter.bi_sector + sectors_handled;
-		goto read_again;
-	} else
-		generic_make_request(read_bio);
+	generic_make_request(read_bio);
 	return;
 }
 
-static void raid10_write_request(struct mddev *mddev, struct bio *bio,
-				 struct r10bio *r10_bio)
+static void raid10_write_one_disk(struct mddev *mddev, struct r10bio *r10_bio,
+				  struct bio *bio, bool replacement,
+				  int n_copy)
 {
-	struct r10conf *conf = mddev->private;
-	int i;
 	const int op = bio_op(bio);
 	const unsigned long do_sync = (bio->bi_opf & REQ_SYNC);
 	const unsigned long do_fua = (bio->bi_opf & REQ_FUA);
 	unsigned long flags;
-	struct md_rdev *blocked_rdev;
 	struct blk_plug_cb *cb;
 	struct raid10_plug_cb *plug = NULL;
+	struct r10conf *conf = mddev->private;
+	struct md_rdev *rdev;
+	int devnum = r10_bio->devs[n_copy].devnum;
+	struct bio *mbio;
+
+	if (replacement) {
+		rdev = conf->mirrors[devnum].replacement;
+		if (rdev == NULL) {
+			/* Replacement just got moved to main 'rdev' */
+			smp_mb();
+			rdev = conf->mirrors[devnum].rdev;
+		}
+	} else
+		rdev = conf->mirrors[devnum].rdev;
+
+	mbio = bio_clone_fast(bio, GFP_NOIO, mddev->bio_set);
+	if (replacement)
+		r10_bio->devs[n_copy].repl_bio = mbio;
+	else
+		r10_bio->devs[n_copy].bio = mbio;
+
+	mbio->bi_iter.bi_sector	= (r10_bio->devs[n_copy].addr +
+				   choose_data_offset(r10_bio, rdev));
+	mbio->bi_bdev = rdev->bdev;
+	mbio->bi_end_io	= raid10_end_write_request;
+	bio_set_op_attrs(mbio, op, do_sync | do_fua);
+	if (!replacement && test_bit(FailFast,
+				     &conf->mirrors[devnum].rdev->flags)
+			 && enough(conf, devnum))
+		mbio->bi_opf |= MD_FAILFAST;
+	mbio->bi_private = r10_bio;
+
+	if (conf->mddev->gendisk)
+		trace_block_bio_remap(bdev_get_queue(mbio->bi_bdev),
+				      mbio, disk_devt(conf->mddev->gendisk),
+				      r10_bio->sector);
+	/* flush_pending_writes() needs access to the rdev so...*/
+	mbio->bi_bdev = (void *)rdev;
+
+	atomic_inc(&r10_bio->remaining);
+
+	cb = blk_check_plugged(raid10_unplug, mddev, sizeof(*plug));
+	if (cb)
+		plug = container_of(cb, struct raid10_plug_cb, cb);
+	else
+		plug = NULL;
+	spin_lock_irqsave(&conf->device_lock, flags);
+	if (plug) {
+		bio_list_add(&plug->pending, mbio);
+		plug->pending_cnt++;
+	} else {
+		bio_list_add(&conf->pending_bio_list, mbio);
+		conf->pending_count++;
+	}
+	spin_unlock_irqrestore(&conf->device_lock, flags);
+	if (!plug)
+		md_wakeup_thread(mddev->thread);
+}
+
+static void raid10_write_request(struct mddev *mddev, struct bio *bio,
+				 struct r10bio *r10_bio)
+{
+	struct r10conf *conf = mddev->private;
+	int i;
+	struct md_rdev *blocked_rdev;
 	sector_t sectors;
-	int sectors_handled;
 	int max_sectors;
 
 	md_write_start(mddev, bio);
@@ -1214,7 +1313,7 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,
 	 */
 	wait_barrier(conf);
 
-	sectors = bio_sectors(bio);
+	sectors = r10_bio->sectors;
 	while (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
 	    bio->bi_iter.bi_sector < conf->reshape_progress &&
 	    bio->bi_iter.bi_sector + sectors > conf->reshape_progress) {
@@ -1262,9 +1361,7 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,
 	 * 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.
+	 * gets its own r10_bio with a set of bios attached.
 	 */
 
 	r10_bio->read_slot = -1; /* make sure repl_bio gets freed */
@@ -1384,145 +1481,31 @@ retry_write:
 		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.
-		 */
+	if (max_sectors < r10_bio->sectors)
 		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);
+
+	if (r10_bio->sectors < bio_sectors(bio)) {
+		struct bio *split = bio_split(bio, r10_bio->sectors,
+					      GFP_NOIO, conf->bio_split);
+		bio_chain(split, bio);
+		generic_make_request(bio);
+		bio = split;
+		r10_bio->master_bio = bio;
 	}
-	sectors_handled = r10_bio->sector + max_sectors -
-		bio->bi_iter.bi_sector;
 
 	atomic_set(&r10_bio->remaining, 1);
 	bitmap_startwrite(mddev->bitmap, r10_bio->sector, r10_bio->sectors, 0);
 
 	for (i = 0; i < conf->copies; i++) {
-		struct bio *mbio;
-		int d = r10_bio->devs[i].devnum;
-		if (r10_bio->devs[i].bio) {
-			struct md_rdev *rdev = conf->mirrors[d].rdev;
-			mbio = bio_clone_fast(bio, GFP_NOIO, mddev->bio_set);
-			bio_trim(mbio, r10_bio->sector - bio->bi_iter.bi_sector,
-				 max_sectors);
-			r10_bio->devs[i].bio = mbio;
-
-			mbio->bi_iter.bi_sector	= (r10_bio->devs[i].addr+
-					   choose_data_offset(r10_bio, rdev));
-			mbio->bi_bdev = rdev->bdev;
-			mbio->bi_end_io	= raid10_end_write_request;
-			bio_set_op_attrs(mbio, op, do_sync | do_fua);
-			if (test_bit(FailFast, &conf->mirrors[d].rdev->flags) &&
-			    enough(conf, d))
-				mbio->bi_opf |= MD_FAILFAST;
-			mbio->bi_private = r10_bio;
-
-			if (conf->mddev->gendisk)
-				trace_block_bio_remap(bdev_get_queue(mbio->bi_bdev),
-						      mbio, disk_devt(conf->mddev->gendisk),
-						      r10_bio->sector);
-			/* flush_pending_writes() needs access to the rdev so...*/
-			mbio->bi_bdev = (void*)rdev;
-
-			atomic_inc(&r10_bio->remaining);
-
-			cb = blk_check_plugged(raid10_unplug, mddev,
-					       sizeof(*plug));
-			if (cb)
-				plug = container_of(cb, struct raid10_plug_cb,
-						    cb);
-			else
-				plug = NULL;
-			spin_lock_irqsave(&conf->device_lock, flags);
-			if (plug) {
-				bio_list_add(&plug->pending, mbio);
-				plug->pending_cnt++;
-			} else {
-				bio_list_add(&conf->pending_bio_list, mbio);
-				conf->pending_count++;
-			}
-			spin_unlock_irqrestore(&conf->device_lock, flags);
-			if (!plug)
-				md_wakeup_thread(mddev->thread);
-		}
-
-		if (r10_bio->devs[i].repl_bio) {
-			struct md_rdev *rdev = conf->mirrors[d].replacement;
-			if (rdev == NULL) {
-				/* Replacement just got moved to main 'rdev' */
-				smp_mb();
-				rdev = conf->mirrors[d].rdev;
-			}
-			mbio = bio_clone_fast(bio, GFP_NOIO, mddev->bio_set);
-			bio_trim(mbio, r10_bio->sector - bio->bi_iter.bi_sector,
-				 max_sectors);
-			r10_bio->devs[i].repl_bio = mbio;
-
-			mbio->bi_iter.bi_sector	= (r10_bio->devs[i].addr +
-					   choose_data_offset(r10_bio, rdev));
-			mbio->bi_bdev = rdev->bdev;
-			mbio->bi_end_io	= raid10_end_write_request;
-			bio_set_op_attrs(mbio, op, do_sync | do_fua);
-			mbio->bi_private = r10_bio;
-
-			if (conf->mddev->gendisk)
-				trace_block_bio_remap(bdev_get_queue(mbio->bi_bdev),
-						      mbio, disk_devt(conf->mddev->gendisk),
-						      r10_bio->sector);
-			/* flush_pending_writes() needs access to the rdev so...*/
-			mbio->bi_bdev = (void*)rdev;
-
-			atomic_inc(&r10_bio->remaining);
-
-			cb = blk_check_plugged(raid10_unplug, mddev,
-					       sizeof(*plug));
-			if (cb)
-				plug = container_of(cb, struct raid10_plug_cb,
-						    cb);
-			else
-				plug = NULL;
-			spin_lock_irqsave(&conf->device_lock, flags);
-			if (plug) {
-				bio_list_add(&plug->pending, mbio);
-				plug->pending_cnt++;
-			} else {
-				bio_list_add(&conf->pending_bio_list, mbio);
-				conf->pending_count++;
-			}
-			spin_unlock_irqrestore(&conf->device_lock, flags);
-			if (!plug)
-				md_wakeup_thread(mddev->thread);
-		}
-	}
-
-	/* Don't remove the bias on 'remaining' (one_write_done) until
-	 * after checking if we need to go around again.
-	 */
-
-	if (sectors_handled < bio_sectors(bio)) {
-		one_write_done(r10_bio);
-		/* 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_sectors(bio) - sectors_handled;
-
-		r10_bio->mddev = mddev;
-		r10_bio->sector = bio->bi_iter.bi_sector + sectors_handled;
-		r10_bio->state = 0;
-		goto retry_write;
+		if (r10_bio->devs[i].bio)
+			raid10_write_one_disk(mddev, r10_bio, bio, false, i);
+		if (r10_bio->devs[i].repl_bio)
+			raid10_write_one_disk(mddev, r10_bio, bio, true, i);
 	}
 	one_write_done(r10_bio);
 }
 
-static void __make_request(struct mddev *mddev, struct bio *bio)
+static void __make_request(struct mddev *mddev, struct bio *bio, int sectors)
 {
 	struct r10conf *conf = mddev->private;
 	struct r10bio *r10_bio;
@@ -1530,21 +1513,12 @@ static void __make_request(struct mddev *mddev, struct bio *bio)
 	r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
 
 	r10_bio->master_bio = bio;
-	r10_bio->sectors = bio_sectors(bio);
+	r10_bio->sectors = sectors;
 
 	r10_bio->mddev = mddev;
 	r10_bio->sector = bio->bi_iter.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;
-	bio_clear_flag(bio, BIO_SEG_VALID);
+	memset(r10_bio->devs, 0, sizeof(r10_bio->devs[0]) * conf->copies);
 
 	if (bio_data_dir(bio) == READ)
 		raid10_read_request(mddev, bio, r10_bio);
@@ -1557,54 +1531,26 @@ static void raid10_make_request(struct mddev *mddev, struct bio *bio)
 	struct r10conf *conf = mddev->private;
 	sector_t chunk_mask = (conf->geo.chunk_mask & conf->prev.chunk_mask);
 	int chunk_sects = chunk_mask + 1;
-
-	struct bio *split;
+	int sectors = bio_sectors(bio);
 
 	if (unlikely(bio->bi_opf & REQ_PREFLUSH)) {
 		md_flush_request(mddev, bio);
 		return;
 	}
 
-	do {
-
-		/*
-		 * If this request crosses a chunk boundary, we need to split
-		 * it.
-		 */
-		if (unlikely((bio->bi_iter.bi_sector & chunk_mask) +
-			     bio_sectors(bio) > chunk_sects
-			     && (conf->geo.near_copies < conf->geo.raid_disks
-				 || conf->prev.near_copies <
-				 conf->prev.raid_disks))) {
-			split = bio_split(bio, chunk_sects -
-					  (bio->bi_iter.bi_sector &
-					   (chunk_sects - 1)),
-					  GFP_NOIO, fs_bio_set);
-			bio_chain(split, bio);
-		} else {
-			split = bio;
-		}
-
-		/*
-		 * If a bio is splitted, the first part of bio will pass
-		 * barrier but the bio is queued in current->bio_list (see
-		 * generic_make_request). If there is a raise_barrier() called
-		 * here, the second part of bio can't pass barrier. But since
-		 * the first part bio isn't dispatched to underlaying disks
-		 * yet, the barrier is never released, hence raise_barrier will
-		 * alays wait. We have a deadlock.
-		 * Note, this only happens in read path. For write path, the
-		 * first part of bio is dispatched in a schedule() call
-		 * (because of blk plug) or offloaded to raid10d.
-		 * Quitting from the function immediately can change the bio
-		 * order queued in bio_list and avoid the deadlock.
-		 */
-		__make_request(mddev, split);
-		if (split != bio && bio_data_dir(bio) == READ) {
-			generic_make_request(bio);
-			break;
-		}
-	} while (split != bio);
+	/*
+	 * If this request crosses a chunk boundary, we need to split
+	 * it.
+	 */
+	if (unlikely((bio->bi_iter.bi_sector & chunk_mask) +
+		     sectors > chunk_sects
+		     && (conf->geo.near_copies < conf->geo.raid_disks
+			 || conf->prev.near_copies <
+			 conf->prev.raid_disks)))
+		sectors = chunk_sects -
+			(bio->bi_iter.bi_sector &
+			 (chunk_sects - 1));
+	__make_request(mddev, bio, sectors);
 
 	/* In case raid10d snuck in to freeze_array */
 	wake_up(&conf->wait_barrier);
@@ -1928,13 +1874,9 @@ static int raid10_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
 			   * but will never see neither -- if they are careful.
 			   */
 		p->replacement = NULL;
-		clear_bit(WantReplacement, &rdev->flags);
-	} else
-		/* We might have just remove the Replacement as faulty
-		 * Clear the flag just in case
-		 */
-		clear_bit(WantReplacement, &rdev->flags);
+	}
 
+	clear_bit(WantReplacement, &rdev->flags);
 	err = md_integrity_register(mddev);
 
 abort:
@@ -1943,17 +1885,9 @@ abort:
 	return err;
 }
 
-static void end_sync_read(struct bio *bio)
+static void __end_sync_read(struct r10bio *r10_bio, struct bio *bio, int d)
 {
-	struct r10bio *r10_bio = bio->bi_private;
 	struct r10conf *conf = r10_bio->mddev->private;
-	int d;
-
-	if (bio == r10_bio->master_bio) {
-		/* this is a reshape read */
-		d = r10_bio->read_slot; /* really the read dev */
-	} else
-		d = find_bio_disk(conf, r10_bio, bio, NULL, NULL);
 
 	if (!bio->bi_error)
 		set_bit(R10BIO_Uptodate, &r10_bio->state);
@@ -1977,6 +1911,23 @@ static void end_sync_read(struct bio *bio)
 	}
 }
 
+static void end_sync_read(struct bio *bio)
+{
+	struct r10bio *r10_bio = get_resync_r10bio(bio);
+	struct r10conf *conf = r10_bio->mddev->private;
+	int d = find_bio_disk(conf, r10_bio, bio, NULL, NULL);
+
+	__end_sync_read(r10_bio, bio, d);
+}
+
+static void end_reshape_read(struct bio *bio)
+{
+	/* reshape read bio isn't allocated from r10buf_pool */
+	struct r10bio *r10_bio = bio->bi_private;
+
+	__end_sync_read(r10_bio, bio, r10_bio->read_slot);
+}
+
 static void end_sync_request(struct r10bio *r10_bio)
 {
 	struct mddev *mddev = r10_bio->mddev;
@@ -2006,7 +1957,7 @@ static void end_sync_request(struct r10bio *r10_bio)
 
 static void end_sync_write(struct bio *bio)
 {
-	struct r10bio *r10_bio = bio->bi_private;
+	struct r10bio *r10_bio = get_resync_r10bio(bio);
 	struct mddev *mddev = r10_bio->mddev;
 	struct r10conf *conf = mddev->private;
 	int d;
@@ -2065,6 +2016,7 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
 	int i, first;
 	struct bio *tbio, *fbio;
 	int vcnt;
+	struct page **tpages, **fpages;
 
 	atomic_set(&r10_bio->remaining, 1);
 
@@ -2080,12 +2032,14 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
 	fbio = r10_bio->devs[i].bio;
 	fbio->bi_iter.bi_size = r10_bio->sectors << 9;
 	fbio->bi_iter.bi_idx = 0;
+	fpages = get_resync_pages(fbio)->pages;
 
 	vcnt = (r10_bio->sectors + (PAGE_SIZE >> 9) - 1) >> (PAGE_SHIFT - 9);
 	/* now find blocks with errors */
 	for (i=0 ; i < conf->copies ; i++) {
 		int  j, d;
 		struct md_rdev *rdev;
+		struct resync_pages *rp;
 
 		tbio = r10_bio->devs[i].bio;
 
@@ -2093,6 +2047,8 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
 			continue;
 		if (i == first)
 			continue;
+
+		tpages = get_resync_pages(tbio)->pages;
 		d = r10_bio->devs[i].devnum;
 		rdev = conf->mirrors[d].rdev;
 		if (!r10_bio->devs[i].bio->bi_error) {
@@ -2105,8 +2061,8 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
 				int len = PAGE_SIZE;
 				if (sectors < (len / 512))
 					len = sectors * 512;
-				if (memcmp(page_address(fbio->bi_io_vec[j].bv_page),
-					   page_address(tbio->bi_io_vec[j].bv_page),
+				if (memcmp(page_address(fpages[j]),
+					   page_address(tpages[j]),
 					   len))
 					break;
 				sectors -= len/512;
@@ -2127,11 +2083,13 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
 		 * First we need to fixup bv_offset, bv_len and
 		 * bi_vecs, as the read request might have corrupted these
 		 */
+		rp = get_resync_pages(tbio);
 		bio_reset(tbio);
 
 		tbio->bi_vcnt = vcnt;
 		tbio->bi_iter.bi_size = fbio->bi_iter.bi_size;
-		tbio->bi_private = r10_bio;
+		rp->raid_bio = r10_bio;
+		tbio->bi_private = rp;
 		tbio->bi_iter.bi_sector = r10_bio->devs[i].addr;
 		tbio->bi_end_io = end_sync_write;
 		bio_set_op_attrs(tbio, REQ_OP_WRITE, 0);
@@ -2202,6 +2160,7 @@ static void fix_recovery_read_error(struct r10bio *r10_bio)
 	int idx = 0;
 	int dr = r10_bio->devs[0].devnum;
 	int dw = r10_bio->devs[1].devnum;
+	struct page **pages = get_resync_pages(bio)->pages;
 
 	while (sectors) {
 		int s = sectors;
@@ -2217,7 +2176,7 @@ static void fix_recovery_read_error(struct r10bio *r10_bio)
 		ok = sync_page_io(rdev,
 				  addr,
 				  s << 9,
-				  bio->bi_io_vec[idx].bv_page,
+				  pages[idx],
 				  REQ_OP_READ, 0, false);
 		if (ok) {
 			rdev = conf->mirrors[dw].rdev;
@@ -2225,7 +2184,7 @@ static void fix_recovery_read_error(struct r10bio *r10_bio)
 			ok = sync_page_io(rdev,
 					  addr,
 					  s << 9,
-					  bio->bi_io_vec[idx].bv_page,
+					  pages[idx],
 					  REQ_OP_WRITE, 0, false);
 			if (!ok) {
 				set_bit(WriteErrorSeen, &rdev->flags);
@@ -2625,9 +2584,6 @@ static void handle_read_error(struct mddev *mddev, struct r10bio *r10_bio)
 	struct bio *bio;
 	struct r10conf *conf = mddev->private;
 	struct md_rdev *rdev = r10_bio->devs[slot].rdev;
-	char b[BDEVNAME_SIZE];
-	unsigned long do_sync;
-	int max_sectors;
 	dev_t bio_dev;
 	sector_t bio_last_sector;
 
@@ -2640,7 +2596,6 @@ static void handle_read_error(struct mddev *mddev, struct r10bio *r10_bio)
 	 * frozen.
 	 */
 	bio = r10_bio->devs[slot].bio;
-	bdevname(bio->bi_bdev, b);
 	bio_dev = bio->bi_bdev->bd_dev;
 	bio_last_sector = r10_bio->devs[slot].addr + rdev->data_offset + r10_bio->sectors;
 	bio_put(bio);
@@ -2656,69 +2611,9 @@ static void handle_read_error(struct mddev *mddev, struct r10bio *r10_bio)
 		md_error(mddev, rdev);
 
 	rdev_dec_pending(rdev, mddev);
-
-read_more:
-	rdev = read_balance(conf, r10_bio, &max_sectors);
-	if (rdev == NULL) {
-		pr_crit_ratelimited("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);
-		return;
-	}
-
-	do_sync = (r10_bio->master_bio->bi_opf & REQ_SYNC);
-	slot = r10_bio->read_slot;
-	pr_err_ratelimited("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_fast(r10_bio->master_bio, GFP_NOIO, mddev->bio_set);
-	bio_trim(bio, r10_bio->sector - bio->bi_iter.bi_sector, max_sectors);
-	r10_bio->devs[slot].bio = bio;
-	r10_bio->devs[slot].rdev = rdev;
-	bio->bi_iter.bi_sector = r10_bio->devs[slot].addr
-		+ choose_data_offset(r10_bio, rdev);
-	bio->bi_bdev = rdev->bdev;
-	bio_set_op_attrs(bio, REQ_OP_READ, do_sync);
-	if (test_bit(FailFast, &rdev->flags) &&
-	    test_bit(R10BIO_FailFast, &r10_bio->state))
-		bio->bi_opf |= MD_FAILFAST;
-	bio->bi_private = r10_bio;
-	bio->bi_end_io = raid10_end_read_request;
-	trace_block_bio_remap(bdev_get_queue(bio->bi_bdev),
-			      bio, bio_dev,
-			      bio_last_sector - r10_bio->sectors);
-
-	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_iter.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);
-
-		r10_bio = mempool_alloc(conf->r10bio_pool,
-					GFP_NOIO);
-		r10_bio->master_bio = mbio;
-		r10_bio->sectors = bio_sectors(mbio) - sectors_handled;
-		r10_bio->state = 0;
-		set_bit(R10BIO_ReadError,
-			&r10_bio->state);
-		r10_bio->mddev = mddev;
-		r10_bio->sector = mbio->bi_iter.bi_sector
-			+ sectors_handled;
-
-		goto read_more;
-	} else
-		generic_make_request(bio);
+	allow_barrier(conf);
+	r10_bio->state = 0;
+	raid10_read_request(mddev, r10_bio->master_bio, r10_bio);
 }
 
 static void handle_write_completed(struct r10conf *conf, struct r10bio *r10_bio)
@@ -2805,6 +2700,11 @@ static void handle_write_completed(struct r10conf *conf, struct r10bio *r10_bio)
 			list_add(&r10_bio->retry_list, &conf->bio_end_io_list);
 			conf->nr_queued++;
 			spin_unlock_irq(&conf->device_lock);
+			/*
+			 * In case freeze_array() is waiting for condition
+			 * nr_pending == nr_queued + extra to be true.
+			 */
+			wake_up(&conf->wait_barrier);
 			md_wakeup_thread(conf->mddev->thread);
 		} else {
 			if (test_bit(R10BIO_WriteError,
@@ -2879,13 +2779,8 @@ static void raid10d(struct md_thread *thread)
 			recovery_request_write(mddev, r10_bio);
 		else if (test_bit(R10BIO_ReadError, &r10_bio->state))
 			handle_read_error(mddev, r10_bio);
-		else {
-			/* just a partial read to be scheduled from a
-			 * separate context
-			 */
-			int slot = r10_bio->read_slot;
-			generic_make_request(r10_bio->devs[slot].bio);
-		}
+		else
+			WARN_ON_ONCE(1);
 
 		cond_resched();
 		if (mddev->sb_flags & ~(1<<MD_SB_CHANGE_PENDING))
@@ -3199,10 +3094,8 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 					}
 				}
 				bio = r10_bio->devs[0].bio;
-				bio_reset(bio);
 				bio->bi_next = biolist;
 				biolist = bio;
-				bio->bi_private = r10_bio;
 				bio->bi_end_io = end_sync_read;
 				bio_set_op_attrs(bio, REQ_OP_READ, 0);
 				if (test_bit(FailFast, &rdev->flags))
@@ -3226,10 +3119,8 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 
 				if (!test_bit(In_sync, &mrdev->flags)) {
 					bio = r10_bio->devs[1].bio;
-					bio_reset(bio);
 					bio->bi_next = biolist;
 					biolist = bio;
-					bio->bi_private = r10_bio;
 					bio->bi_end_io = end_sync_write;
 					bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
 					bio->bi_iter.bi_sector = to_addr
@@ -3254,10 +3145,8 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 				if (mreplace == NULL || bio == NULL ||
 				    test_bit(Faulty, &mreplace->flags))
 					break;
-				bio_reset(bio);
 				bio->bi_next = biolist;
 				biolist = bio;
-				bio->bi_private = r10_bio;
 				bio->bi_end_io = end_sync_write;
 				bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
 				bio->bi_iter.bi_sector = to_addr +
@@ -3379,7 +3268,6 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 				r10_bio->devs[i].repl_bio->bi_end_io = NULL;
 
 			bio = r10_bio->devs[i].bio;
-			bio_reset(bio);
 			bio->bi_error = -EIO;
 			rcu_read_lock();
 			rdev = rcu_dereference(conf->mirrors[d].rdev);
@@ -3404,7 +3292,6 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 			atomic_inc(&r10_bio->remaining);
 			bio->bi_next = biolist;
 			biolist = bio;
-			bio->bi_private = r10_bio;
 			bio->bi_end_io = end_sync_read;
 			bio_set_op_attrs(bio, REQ_OP_READ, 0);
 			if (test_bit(FailFast, &conf->mirrors[d].rdev->flags))
@@ -3423,13 +3310,11 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 
 			/* Need to set up for writing to the replacement */
 			bio = r10_bio->devs[i].repl_bio;
-			bio_reset(bio);
 			bio->bi_error = -EIO;
 
 			sector = r10_bio->devs[i].addr;
 			bio->bi_next = biolist;
 			biolist = bio;
-			bio->bi_private = r10_bio;
 			bio->bi_end_io = end_sync_write;
 			bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
 			if (test_bit(FailFast, &conf->mirrors[d].rdev->flags))
@@ -3468,27 +3353,17 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 		if (len == 0)
 			break;
 		for (bio= biolist ; bio ; bio=bio->bi_next) {
-			struct bio *bio2;
-			page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
-			if (bio_add_page(bio, page, len, 0))
-				continue;
-
-			/* stop here */
-			bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
-			for (bio2 = biolist;
-			     bio2 && bio2 != bio;
-			     bio2 = bio2->bi_next) {
-				/* remove last page from this bio */
-				bio2->bi_vcnt--;
-				bio2->bi_iter.bi_size -= len;
-				bio_clear_flag(bio2, BIO_SEG_VALID);
-			}
-			goto bio_full;
+			struct resync_pages *rp = get_resync_pages(bio);
+			page = resync_fetch_page(rp, rp->idx++);
+			/*
+			 * won't fail because the vec table is big enough
+			 * to hold all these pages
+			 */
+			bio_add_page(bio, page, len, 0);
 		}
 		nr_sectors += len>>9;
 		sector_nr += len>>9;
-	} while (biolist->bi_vcnt < RESYNC_PAGES);
- bio_full:
+	} while (get_resync_pages(biolist)->idx < RESYNC_PAGES);
 	r10_bio->sectors = nr_sectors;
 
 	while (biolist) {
@@ -3496,7 +3371,7 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
 		biolist = biolist->bi_next;
 
 		bio->bi_next = NULL;
-		r10_bio = bio->bi_private;
+		r10_bio = get_resync_r10bio(bio);
 		r10_bio->sectors = nr_sectors;
 
 		if (bio->bi_end_io == end_sync_read) {
@@ -3678,6 +3553,10 @@ static struct r10conf *setup_conf(struct mddev *mddev)
 	if (!conf->r10bio_pool)
 		goto out;
 
+	conf->bio_split = bioset_create(BIO_POOL_SIZE, 0);
+	if (!conf->bio_split)
+		goto out;
+
 	calc_sectors(conf, mddev->dev_sectors);
 	if (mddev->reshape_position == MaxSector) {
 		conf->prev = conf->geo;
@@ -3715,6 +3594,8 @@ static struct r10conf *setup_conf(struct mddev *mddev)
 		mempool_destroy(conf->r10bio_pool);
 		kfree(conf->mirrors);
 		safe_put_page(conf->tmppage);
+		if (conf->bio_split)
+			bioset_free(conf->bio_split);
 		kfree(conf);
 	}
 	return ERR_PTR(err);
@@ -3760,7 +3641,6 @@ static int raid10_run(struct mddev *mddev)
 
 	rdev_for_each(rdev, mddev) {
 		long long diff;
-		struct request_queue *q;
 
 		disk_idx = rdev->raid_disk;
 		if (disk_idx < 0)
@@ -3779,7 +3659,6 @@ static int raid10_run(struct mddev *mddev)
 				goto out_free_conf;
 			disk->rdev = rdev;
 		}
-		q = bdev_get_queue(rdev->bdev);
 		diff = (rdev->new_data_offset - rdev->data_offset);
 		if (!mddev->reshape_backwards)
 			diff = -diff;
@@ -3796,6 +3675,7 @@ static int raid10_run(struct mddev *mddev)
 
 		if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
 			discard_supported = true;
+		first = 0;
 	}
 
 	if (mddev->queue) {
@@ -3925,6 +3805,8 @@ static void raid10_free(struct mddev *mddev, void *priv)
 	kfree(conf->mirrors);
 	kfree(conf->mirrors_old);
 	kfree(conf->mirrors_new);
+	if (conf->bio_split)
+		bioset_free(conf->bio_split);
 	kfree(conf);
 }
 
@@ -4198,6 +4080,7 @@ static int raid10_start_reshape(struct mddev *mddev)
 				diff = 0;
 			if (first || diff < min_offset_diff)
 				min_offset_diff = diff;
+			first = 0;
 		}
 	}
 
@@ -4388,6 +4271,7 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr,
 	struct bio *blist;
 	struct bio *bio, *read_bio;
 	int sectors_done = 0;
+	struct page **pages;
 
 	if (sector_nr == 0) {
 		/* If restarting in the middle, skip the initial sectors */
@@ -4508,7 +4392,7 @@ read_more:
 	read_bio->bi_iter.bi_sector = (r10_bio->devs[r10_bio->read_slot].addr
 			       + rdev->data_offset);
 	read_bio->bi_private = r10_bio;
-	read_bio->bi_end_io = end_sync_read;
+	read_bio->bi_end_io = end_reshape_read;
 	bio_set_op_attrs(read_bio, REQ_OP_READ, 0);
 	read_bio->bi_flags &= (~0UL << BIO_RESET_BITS);
 	read_bio->bi_error = 0;
@@ -4538,11 +4422,9 @@ read_more:
 		if (!rdev2 || test_bit(Faulty, &rdev2->flags))
 			continue;
 
-		bio_reset(b);
 		b->bi_bdev = rdev2->bdev;
 		b->bi_iter.bi_sector = r10_bio->devs[s/2].addr +
 			rdev2->new_data_offset;
-		b->bi_private = r10_bio;
 		b->bi_end_io = end_reshape_write;
 		bio_set_op_attrs(b, REQ_OP_WRITE, 0);
 		b->bi_next = blist;
@@ -4552,31 +4434,22 @@ read_more:
 	/* Now add as many pages as possible to all of these bios. */
 
 	nr_sectors = 0;
+	pages = get_resync_pages(r10_bio->devs[0].bio)->pages;
 	for (s = 0 ; s < max_sectors; s += PAGE_SIZE >> 9) {
-		struct page *page = r10_bio->devs[0].bio->bi_io_vec[s/(PAGE_SIZE>>9)].bv_page;
+		struct page *page = pages[s / (PAGE_SIZE >> 9)];
 		int len = (max_sectors - s) << 9;
 		if (len > PAGE_SIZE)
 			len = PAGE_SIZE;
 		for (bio = blist; bio ; bio = bio->bi_next) {
-			struct bio *bio2;
-			if (bio_add_page(bio, page, len, 0))
-				continue;
-
-			/* Didn't fit, must stop */
-			for (bio2 = blist;
-			     bio2 && bio2 != bio;
-			     bio2 = bio2->bi_next) {
-				/* Remove last page from this bio */
-				bio2->bi_vcnt--;
-				bio2->bi_iter.bi_size -= len;
-				bio_clear_flag(bio2, BIO_SEG_VALID);
-			}
-			goto bio_full;
+			/*
+			 * won't fail because the vec table is big enough
+			 * to hold all these pages
+			 */
+			bio_add_page(bio, page, len, 0);
 		}
 		sector_nr += len >> 9;
 		nr_sectors += len >> 9;
 	}
-bio_full:
 	rcu_read_unlock();
 	r10_bio->sectors = nr_sectors;
 
@@ -4690,7 +4563,10 @@ static int handle_reshape_read_error(struct mddev *mddev,
 	struct r10bio *r10b = &on_stack.r10_bio;
 	int slot = 0;
 	int idx = 0;
-	struct bio_vec *bvec = r10_bio->master_bio->bi_io_vec;
+	struct page **pages;
+
+	/* reshape IOs share pages from .devs[0].bio */
+	pages = get_resync_pages(r10_bio->devs[0].bio)->pages;
 
 	r10b->sector = r10_bio->sector;
 	__raid10_find_phys(&conf->prev, r10b);
@@ -4719,7 +4595,7 @@ static int handle_reshape_read_error(struct mddev *mddev,
 			success = sync_page_io(rdev,
 					       addr,
 					       s << 9,
-					       bvec[idx].bv_page,
+					       pages[idx],
 					       REQ_OP_READ, 0, false);
 			rdev_dec_pending(rdev, mddev);
 			rcu_read_lock();
@@ -4747,7 +4623,7 @@ static int handle_reshape_read_error(struct mddev *mddev,
 
 static void end_reshape_write(struct bio *bio)
 {
-	struct r10bio *r10_bio = bio->bi_private;
+	struct r10bio *r10_bio = get_resync_r10bio(bio);
 	struct mddev *mddev = r10_bio->mddev;
 	struct r10conf *conf = mddev->private;
 	int d;