Btrfs, raid56: support parity scrub on raid56

The implementation is:
- Read and check all the data with checksum in the same stripe.
  All the data which has checksum is COW data, and we are sure
  that it is not changed though we don't lock the stripe. because
  the space of that data just can be reclaimed after the current
  transction is committed, and then the fs can use it to store the
  other data, but when doing scrub, we hold the current transaction,
  that is that data can not be recovered, it is safe that read and check
  it out of the stripe lock.
- Lock the stripe
- Read out all the data without checksum and parity
  The data without checksum and the parity may be changed if we don't
  lock the stripe, so we need read it in the stripe lock context.
- Check the parity
- Re-calculate the new parity and write back it if the old parity
  is not right
- Unlock the stripe

If we can not read out the data or the data we read is corrupted,
we will try to repair it. If the repair fails. we will mark the
horizontal sub-stripe(pages on the same horizontal) as corrupted
sub-stripe, and we will skip the parity check and repair of that
horizontal sub-stripe.

And in order to skip the horizontal sub-stripe that has no data, we
introduce a bitmap. If there is some data on the horizontal sub-stripe,
we will the relative bit to 1, and when we check and repair the
parity, we will skip those horizontal sub-stripes that the relative
bits is 0.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>

1 files changed, 595 insertions, 14 deletions

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index ca4b9eb8b5da..7f95afcf9fd3 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -74,6 +74,7 @@ struct scrub_page {
 	struct scrub_block	*sblock;
 	struct page		*page;
 	struct btrfs_device	*dev;
+	struct list_head	list;
 	u64			flags;  /* extent flags */
 	u64			generation;
 	u64			logical;
@@ -114,14 +115,52 @@ struct scrub_block {
 	atomic_t		outstanding_pages;
 	atomic_t		ref_count; /* free mem on transition to zero */
 	struct scrub_ctx	*sctx;
+	struct scrub_parity	*sparity;
 	struct {
 		unsigned int	header_error:1;
 		unsigned int	checksum_error:1;
 		unsigned int	no_io_error_seen:1;
 		unsigned int	generation_error:1; /* also sets header_error */
+
+		/* The following is for the data used to check parity */
+		/* It is for the data with checksum */
+		unsigned int	data_corrected:1;
 	};
 };
 
+/* Used for the chunks with parity stripe such RAID5/6 */
+struct scrub_parity {
+	struct scrub_ctx	*sctx;
+
+	struct btrfs_device	*scrub_dev;
+
+	u64			logic_start;
+
+	u64			logic_end;
+
+	int			nsectors;
+
+	int			stripe_len;
+
+	atomic_t		ref_count;
+
+	struct list_head	spages;
+
+	/* Work of parity check and repair */
+	struct btrfs_work	work;
+
+	/* Mark the parity blocks which have data */
+	unsigned long		*dbitmap;
+
+	/*
+	 * Mark the parity blocks which have data, but errors happen when
+	 * read data or check data
+	 */
+	unsigned long		*ebitmap;
+
+	unsigned long		bitmap[0];
+};
+
 struct scrub_wr_ctx {
 	struct scrub_bio *wr_curr_bio;
 	struct btrfs_device *tgtdev;
@@ -227,6 +266,8 @@ static void scrub_block_get(struct scrub_block *sblock);
 static void scrub_block_put(struct scrub_block *sblock);
 static void scrub_page_get(struct scrub_page *spage);
 static void scrub_page_put(struct scrub_page *spage);
+static void scrub_parity_get(struct scrub_parity *sparity);
+static void scrub_parity_put(struct scrub_parity *sparity);
 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
 				    struct scrub_page *spage);
 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
@@ -943,6 +984,7 @@ static int scrub_handle_errored_block(struct scrub_block *sblock_to_check)
 		 */
 		spin_lock(&sctx->stat_lock);
 		sctx->stat.unverified_errors++;
+		sblock_to_check->data_corrected = 1;
 		spin_unlock(&sctx->stat_lock);
 
 		if (sctx->is_dev_replace)
@@ -1203,6 +1245,7 @@ nodatasum_case:
 corrected_error:
 			spin_lock(&sctx->stat_lock);
 			sctx->stat.corrected_errors++;
+			sblock_to_check->data_corrected = 1;
 			spin_unlock(&sctx->stat_lock);
 			printk_ratelimited_in_rcu(KERN_ERR
 				"BTRFS: fixed up error at logical %llu on dev %s\n",
@@ -1644,6 +1687,13 @@ static void scrub_write_block_to_dev_replace(struct scrub_block *sblock)
 {
 	int page_num;
 
+	/*
+	 * This block is used for the check of the parity on the source device,
+	 * so the data needn't be written into the destination device.
+	 */
+	if (sblock->sparity)
+		return;
+
 	for (page_num = 0; page_num < sblock->page_count; page_num++) {
 		int ret;
 
@@ -2025,6 +2075,9 @@ static void scrub_block_put(struct scrub_block *sblock)
 	if (atomic_dec_and_test(&sblock->ref_count)) {
 		int i;
 
+		if (sblock->sparity)
+			scrub_parity_put(sblock->sparity);
+
 		for (i = 0; i < sblock->page_count; i++)
 			scrub_page_put(sblock->pagev[i]);
 		kfree(sblock);
@@ -2282,9 +2335,51 @@ static void scrub_bio_end_io_worker(struct btrfs_work *work)
 	scrub_pending_bio_dec(sctx);
 }
 
+static inline void __scrub_mark_bitmap(struct scrub_parity *sparity,
+				       unsigned long *bitmap,
+				       u64 start, u64 len)
+{
+	int offset;
+	int nsectors;
+	int sectorsize = sparity->sctx->dev_root->sectorsize;
+
+	if (len >= sparity->stripe_len) {
+		bitmap_set(bitmap, 0, sparity->nsectors);
+		return;
+	}
+
+	start -= sparity->logic_start;
+	offset = (int)do_div(start, sparity->stripe_len);
+	offset /= sectorsize;
+	nsectors = (int)len / sectorsize;
+
+	if (offset + nsectors <= sparity->nsectors) {
+		bitmap_set(bitmap, offset, nsectors);
+		return;
+	}
+
+	bitmap_set(bitmap, offset, sparity->nsectors - offset);
+	bitmap_set(bitmap, 0, nsectors - (sparity->nsectors - offset));
+}
+
+static inline void scrub_parity_mark_sectors_error(struct scrub_parity *sparity,
+						   u64 start, u64 len)
+{
+	__scrub_mark_bitmap(sparity, sparity->ebitmap, start, len);
+}
+
+static inline void scrub_parity_mark_sectors_data(struct scrub_parity *sparity,
+						  u64 start, u64 len)
+{
+	__scrub_mark_bitmap(sparity, sparity->dbitmap, start, len);
+}
+
 static void scrub_block_complete(struct scrub_block *sblock)
 {
+	int corrupted = 0;
+
 	if (!sblock->no_io_error_seen) {
+		corrupted = 1;
 		scrub_handle_errored_block(sblock);
 	} else {
 		/*
@@ -2292,9 +2387,19 @@ static void scrub_block_complete(struct scrub_block *sblock)
 		 * dev replace case, otherwise write here in dev replace
 		 * case.
 		 */
-		if (!scrub_checksum(sblock) && sblock->sctx->is_dev_replace)
+		corrupted = scrub_checksum(sblock);
+		if (!corrupted && sblock->sctx->is_dev_replace)
 			scrub_write_block_to_dev_replace(sblock);
 	}
+
+	if (sblock->sparity && corrupted && !sblock->data_corrected) {
+		u64 start = sblock->pagev[0]->logical;
+		u64 end = sblock->pagev[sblock->page_count - 1]->logical +
+			  PAGE_SIZE;
+
+		scrub_parity_mark_sectors_error(sblock->sparity,
+						start, end - start);
+	}
 }
 
 static int scrub_find_csum(struct scrub_ctx *sctx, u64 logical, u64 len,
@@ -2386,6 +2491,132 @@ behind_scrub_pages:
 	return 0;
 }
 
+static int scrub_pages_for_parity(struct scrub_parity *sparity,
+				  u64 logical, u64 len,
+				  u64 physical, struct btrfs_device *dev,
+				  u64 flags, u64 gen, int mirror_num, u8 *csum)
+{
+	struct scrub_ctx *sctx = sparity->sctx;
+	struct scrub_block *sblock;
+	int index;
+
+	sblock = kzalloc(sizeof(*sblock), GFP_NOFS);
+	if (!sblock) {
+		spin_lock(&sctx->stat_lock);
+		sctx->stat.malloc_errors++;
+		spin_unlock(&sctx->stat_lock);
+		return -ENOMEM;
+	}
+
+	/* one ref inside this function, plus one for each page added to
+	 * a bio later on */
+	atomic_set(&sblock->ref_count, 1);
+	sblock->sctx = sctx;
+	sblock->no_io_error_seen = 1;
+	sblock->sparity = sparity;
+	scrub_parity_get(sparity);
+
+	for (index = 0; len > 0; index++) {
+		struct scrub_page *spage;
+		u64 l = min_t(u64, len, PAGE_SIZE);
+
+		spage = kzalloc(sizeof(*spage), GFP_NOFS);
+		if (!spage) {
+leave_nomem:
+			spin_lock(&sctx->stat_lock);
+			sctx->stat.malloc_errors++;
+			spin_unlock(&sctx->stat_lock);
+			scrub_block_put(sblock);
+			return -ENOMEM;
+		}
+		BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
+		/* For scrub block */
+		scrub_page_get(spage);
+		sblock->pagev[index] = spage;
+		/* For scrub parity */
+		scrub_page_get(spage);
+		list_add_tail(&spage->list, &sparity->spages);
+		spage->sblock = sblock;
+		spage->dev = dev;
+		spage->flags = flags;
+		spage->generation = gen;
+		spage->logical = logical;
+		spage->physical = physical;
+		spage->mirror_num = mirror_num;
+		if (csum) {
+			spage->have_csum = 1;
+			memcpy(spage->csum, csum, sctx->csum_size);
+		} else {
+			spage->have_csum = 0;
+		}
+		sblock->page_count++;
+		spage->page = alloc_page(GFP_NOFS);
+		if (!spage->page)
+			goto leave_nomem;
+		len -= l;
+		logical += l;
+		physical += l;
+	}
+
+	WARN_ON(sblock->page_count == 0);
+	for (index = 0; index < sblock->page_count; index++) {
+		struct scrub_page *spage = sblock->pagev[index];
+		int ret;
+
+		ret = scrub_add_page_to_rd_bio(sctx, spage);
+		if (ret) {
+			scrub_block_put(sblock);
+			return ret;
+		}
+	}
+
+	/* last one frees, either here or in bio completion for last page */
+	scrub_block_put(sblock);
+	return 0;
+}
+
+static int scrub_extent_for_parity(struct scrub_parity *sparity,
+				   u64 logical, u64 len,
+				   u64 physical, struct btrfs_device *dev,
+				   u64 flags, u64 gen, int mirror_num)
+{
+	struct scrub_ctx *sctx = sparity->sctx;
+	int ret;
+	u8 csum[BTRFS_CSUM_SIZE];
+	u32 blocksize;
+
+	if (flags & BTRFS_EXTENT_FLAG_DATA) {
+		blocksize = sctx->sectorsize;
+	} else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
+		blocksize = sctx->nodesize;
+	} else {
+		blocksize = sctx->sectorsize;
+		WARN_ON(1);
+	}
+
+	while (len) {
+		u64 l = min_t(u64, len, blocksize);
+		int have_csum = 0;
+
+		if (flags & BTRFS_EXTENT_FLAG_DATA) {
+			/* push csums to sbio */
+			have_csum = scrub_find_csum(sctx, logical, l, csum);
+			if (have_csum == 0)
+				goto skip;
+		}
+		ret = scrub_pages_for_parity(sparity, logical, l, physical, dev,
+					     flags, gen, mirror_num,
+					     have_csum ? csum : NULL);
+skip:
+		if (ret)
+			return ret;
+		len -= l;
+		logical += l;
+		physical += l;
+	}
+	return 0;
+}
+
 /*
  * Given a physical address, this will calculate it's
  * logical offset. if this is a parity stripe, it will return
@@ -2394,7 +2625,8 @@ behind_scrub_pages:
  * return 0 if it is a data stripe, 1 means parity stripe.
  */
 static int get_raid56_logic_offset(u64 physical, int num,
-				   struct map_lookup *map, u64 *offset)
+				   struct map_lookup *map, u64 *offset,
+				   u64 *stripe_start)
 {
 	int i;
 	int j = 0;
@@ -2405,6 +2637,9 @@ static int get_raid56_logic_offset(u64 physical, int num,
 
 	last_offset = (physical - map->stripes[num].physical) *
 		      nr_data_stripes(map);
+	if (stripe_start)
+		*stripe_start = last_offset;
+
 	*offset = last_offset;
 	for (i = 0; i < nr_data_stripes(map); i++) {
 		*offset = last_offset + i * map->stripe_len;
@@ -2427,13 +2662,330 @@ static int get_raid56_logic_offset(u64 physical, int num,
 	return 1;
 }
 
+static void scrub_free_parity(struct scrub_parity *sparity)
+{
+	struct scrub_ctx *sctx = sparity->sctx;
+	struct scrub_page *curr, *next;
+	int nbits;
+
+	nbits = bitmap_weight(sparity->ebitmap, sparity->nsectors);
+	if (nbits) {
+		spin_lock(&sctx->stat_lock);
+		sctx->stat.read_errors += nbits;
+		sctx->stat.uncorrectable_errors += nbits;
+		spin_unlock(&sctx->stat_lock);
+	}
+
+	list_for_each_entry_safe(curr, next, &sparity->spages, list) {
+		list_del_init(&curr->list);
+		scrub_page_put(curr);
+	}
+
+	kfree(sparity);
+}
+
+static void scrub_parity_bio_endio(struct bio *bio, int error)
+{
+	struct scrub_parity *sparity = (struct scrub_parity *)bio->bi_private;
+	struct scrub_ctx *sctx = sparity->sctx;
+
+	if (error)
+		bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
+			  sparity->nsectors);
+
+	scrub_free_parity(sparity);
+	scrub_pending_bio_dec(sctx);
+	bio_put(bio);
+}
+
+static void scrub_parity_check_and_repair(struct scrub_parity *sparity)
+{
+	struct scrub_ctx *sctx = sparity->sctx;
+	struct bio *bio;
+	struct btrfs_raid_bio *rbio;
+	struct scrub_page *spage;
+	struct btrfs_bio *bbio = NULL;
+	u64 *raid_map = NULL;
+	u64 length;
+	int ret;
+
+	if (!bitmap_andnot(sparity->dbitmap, sparity->dbitmap, sparity->ebitmap,
+			   sparity->nsectors))
+		goto out;
+
+	length = sparity->logic_end - sparity->logic_start + 1;
+	ret = btrfs_map_sblock(sctx->dev_root->fs_info, REQ_GET_READ_MIRRORS,
+			       sparity->logic_start,
+			       &length, &bbio, 0, &raid_map);
+	if (ret || !bbio || !raid_map)
+		goto bbio_out;
+
+	bio = btrfs_io_bio_alloc(GFP_NOFS, 0);
+	if (!bio)
+		goto bbio_out;
+
+	bio->bi_iter.bi_sector = sparity->logic_start >> 9;
+	bio->bi_private = sparity;
+	bio->bi_end_io = scrub_parity_bio_endio;
+
+	rbio = raid56_parity_alloc_scrub_rbio(sctx->dev_root, bio, bbio,
+					      raid_map, length,
+					      sparity->scrub_dev,
+					      sparity->dbitmap,
+					      sparity->nsectors);
+	if (!rbio)
+		goto rbio_out;
+
+	list_for_each_entry(spage, &sparity->spages, list)
+		raid56_parity_add_scrub_pages(rbio, spage->page,
+					      spage->logical);
+
+	scrub_pending_bio_inc(sctx);
+	raid56_parity_submit_scrub_rbio(rbio);
+	return;
+
+rbio_out:
+	bio_put(bio);
+bbio_out:
+	kfree(bbio);
+	kfree(raid_map);
+	bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
+		  sparity->nsectors);
+	spin_lock(&sctx->stat_lock);
+	sctx->stat.malloc_errors++;
+	spin_unlock(&sctx->stat_lock);
+out:
+	scrub_free_parity(sparity);
+}
+
+static inline int scrub_calc_parity_bitmap_len(int nsectors)
+{
+	return DIV_ROUND_UP(nsectors, BITS_PER_LONG) * (BITS_PER_LONG / 8);
+}
+
+static void scrub_parity_get(struct scrub_parity *sparity)
+{
+	atomic_inc(&sparity->ref_count);
+}
+
+static void scrub_parity_put(struct scrub_parity *sparity)
+{
+	if (!atomic_dec_and_test(&sparity->ref_count))
+		return;
+
+	scrub_parity_check_and_repair(sparity);
+}
+
+static noinline_for_stack int scrub_raid56_parity(struct scrub_ctx *sctx,
+						  struct map_lookup *map,
+						  struct btrfs_device *sdev,
+						  struct btrfs_path *path,
+						  u64 logic_start,
+						  u64 logic_end)
+{
+	struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
+	struct btrfs_root *root = fs_info->extent_root;
+	struct btrfs_root *csum_root = fs_info->csum_root;
+	struct btrfs_extent_item *extent;
+	u64 flags;
+	int ret;
+	int slot;
+	struct extent_buffer *l;
+	struct btrfs_key key;
+	u64 generation;
+	u64 extent_logical;
+	u64 extent_physical;
+	u64 extent_len;
+	struct btrfs_device *extent_dev;
+	struct scrub_parity *sparity;
+	int nsectors;
+	int bitmap_len;
+	int extent_mirror_num;
+	int stop_loop = 0;
+
+	nsectors = map->stripe_len / root->sectorsize;
+	bitmap_len = scrub_calc_parity_bitmap_len(nsectors);
+	sparity = kzalloc(sizeof(struct scrub_parity) + 2 * bitmap_len,
+			  GFP_NOFS);
+	if (!sparity) {
+		spin_lock(&sctx->stat_lock);
+		sctx->stat.malloc_errors++;
+		spin_unlock(&sctx->stat_lock);
+		return -ENOMEM;
+	}
+
+	sparity->stripe_len = map->stripe_len;
+	sparity->nsectors = nsectors;
+	sparity->sctx = sctx;
+	sparity->scrub_dev = sdev;
+	sparity->logic_start = logic_start;
+	sparity->logic_end = logic_end;
+	atomic_set(&sparity->ref_count, 1);
+	INIT_LIST_HEAD(&sparity->spages);
+	sparity->dbitmap = sparity->bitmap;
+	sparity->ebitmap = (void *)sparity->bitmap + bitmap_len;
+
+	ret = 0;
+	while (logic_start < logic_end) {
+		if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
+			key.type = BTRFS_METADATA_ITEM_KEY;
+		else
+			key.type = BTRFS_EXTENT_ITEM_KEY;
+		key.objectid = logic_start;
+		key.offset = (u64)-1;
+
+		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+		if (ret < 0)
+			goto out;
+
+		if (ret > 0) {
+			ret = btrfs_previous_extent_item(root, path, 0);
+			if (ret < 0)
+				goto out;
+			if (ret > 0) {
+				btrfs_release_path(path);
+				ret = btrfs_search_slot(NULL, root, &key,
+							path, 0, 0);
+				if (ret < 0)
+					goto out;
+			}
+		}
+
+		stop_loop = 0;
+		while (1) {
+			u64 bytes;
+
+			l = path->nodes[0];
+			slot = path->slots[0];
+			if (slot >= btrfs_header_nritems(l)) {
+				ret = btrfs_next_leaf(root, path);
+				if (ret == 0)
+					continue;
+				if (ret < 0)
+					goto out;
+
+				stop_loop = 1;
+				break;
+			}
+			btrfs_item_key_to_cpu(l, &key, slot);
+
+			if (key.type == BTRFS_METADATA_ITEM_KEY)
+				bytes = root->nodesize;
+			else
+				bytes = key.offset;
+
+			if (key.objectid + bytes <= logic_start)
+				goto next;
+
+			if (key.type != BTRFS_EXTENT_ITEM_KEY &&
+			    key.type != BTRFS_METADATA_ITEM_KEY)
+				goto next;
+
+			if (key.objectid > logic_end) {
+				stop_loop = 1;
+				break;
+			}
+
+			while (key.objectid >= logic_start + map->stripe_len)
+				logic_start += map->stripe_len;
+
+			extent = btrfs_item_ptr(l, slot,
+						struct btrfs_extent_item);
+			flags = btrfs_extent_flags(l, extent);
+			generation = btrfs_extent_generation(l, extent);
+
+			if (key.objectid < logic_start &&
+			    (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)) {
+				btrfs_err(fs_info,
+					  "scrub: tree block %llu spanning stripes, ignored. logical=%llu",
+					   key.objectid, logic_start);
+				goto next;
+			}
+again:
+			extent_logical = key.objectid;
+			extent_len = bytes;
+
+			if (extent_logical < logic_start) {
+				extent_len -= logic_start - extent_logical;
+				extent_logical = logic_start;
+			}
+
+			if (extent_logical + extent_len >
+			    logic_start + map->stripe_len)
+				extent_len = logic_start + map->stripe_len -
+					     extent_logical;
+
+			scrub_parity_mark_sectors_data(sparity, extent_logical,
+						       extent_len);
+
+			scrub_remap_extent(fs_info, extent_logical,
+					   extent_len, &extent_physical,
+					   &extent_dev,
+					   &extent_mirror_num);
+
+			ret = btrfs_lookup_csums_range(csum_root,
+						extent_logical,
+						extent_logical + extent_len - 1,
+						&sctx->csum_list, 1);
+			if (ret)
+				goto out;
+
+			ret = scrub_extent_for_parity(sparity, extent_logical,
+						      extent_len,
+						      extent_physical,
+						      extent_dev, flags,
+						      generation,
+						      extent_mirror_num);
+			if (ret)
+				goto out;
+
+			scrub_free_csums(sctx);
+			if (extent_logical + extent_len <
+			    key.objectid + bytes) {
+				logic_start += map->stripe_len;
+
+				if (logic_start >= logic_end) {
+					stop_loop = 1;
+					break;
+				}
+
+				if (logic_start < key.objectid + bytes) {
+					cond_resched();
+					goto again;
+				}
+			}
+next:
+			path->slots[0]++;
+		}
+
+		btrfs_release_path(path);
+
+		if (stop_loop)
+			break;
+
+		logic_start += map->stripe_len;
+	}
+out:
+	if (ret < 0)
+		scrub_parity_mark_sectors_error(sparity, logic_start,
+						logic_end - logic_start + 1);
+	scrub_parity_put(sparity);
+	scrub_submit(sctx);
+	mutex_lock(&sctx->wr_ctx.wr_lock);
+	scrub_wr_submit(sctx);
+	mutex_unlock(&sctx->wr_ctx.wr_lock);
+
+	btrfs_release_path(path);
+	return ret < 0 ? ret : 0;
+}
+
 static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
 					   struct map_lookup *map,
 					   struct btrfs_device *scrub_dev,
 					   int num, u64 base, u64 length,
 					   int is_dev_replace)
 {
-	struct btrfs_path *path;
+	struct btrfs_path *path, *ppath;
 	struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
 	struct btrfs_root *root = fs_info->extent_root;
 	struct btrfs_root *csum_root = fs_info->csum_root;
@@ -2460,6 +3012,8 @@ static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
 	u64 extent_logical;
 	u64 extent_physical;
 	u64 extent_len;
+	u64 stripe_logical;
+	u64 stripe_end;
 	struct btrfs_device *extent_dev;
 	int extent_mirror_num;
 	int stop_loop = 0;
@@ -2485,7 +3039,7 @@ static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
 		mirror_num = num % map->num_stripes + 1;
 	} else if (map->type & (BTRFS_BLOCK_GROUP_RAID5 |
 				BTRFS_BLOCK_GROUP_RAID6)) {
-		get_raid56_logic_offset(physical, num, map, &offset);
+		get_raid56_logic_offset(physical, num, map, &offset, NULL);
 		increment = map->stripe_len * nr_data_stripes(map);
 		mirror_num = 1;
 	} else {
@@ -2497,6 +3051,12 @@ static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
 	if (!path)
 		return -ENOMEM;
 
+	ppath = btrfs_alloc_path();
+	if (!ppath) {
+		btrfs_free_path(ppath);
+		return -ENOMEM;
+	}
+
 	/*
 	 * work on commit root. The related disk blocks are static as
 	 * long as COW is applied. This means, it is save to rewrite
@@ -2515,7 +3075,7 @@ static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
 	if (map->type & (BTRFS_BLOCK_GROUP_RAID5 |
 			 BTRFS_BLOCK_GROUP_RAID6)) {
 		get_raid56_logic_offset(physical_end, num,
-					map, &logic_end);
+					map, &logic_end, NULL);
 		logic_end += base;
 	} else {
 		logic_end = logical + increment * nstripes;
@@ -2562,10 +3122,18 @@ static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
 		if (map->type & (BTRFS_BLOCK_GROUP_RAID5 |
 				BTRFS_BLOCK_GROUP_RAID6)) {
 			ret = get_raid56_logic_offset(physical, num,
-					map, &logical);
+					map, &logical, &stripe_logical);
 			logical += base;
-			if (ret)
+			if (ret) {
+				stripe_logical += base;
+				stripe_end = stripe_logical + increment - 1;
+				ret = scrub_raid56_parity(sctx, map, scrub_dev,
+						ppath, stripe_logical,
+						stripe_end);
+				if (ret)
+					goto out;
 				goto skip;
+			}
 		}
 		/*
 		 * canceled?
@@ -2716,13 +3284,25 @@ again:
 					 * loop until we find next data stripe
 					 * or we have finished all stripes.
 					 */
-					do {
-						physical += map->stripe_len;
-						ret = get_raid56_logic_offset(
-								physical, num,
-								map, &logical);
-						logical += base;
-					} while (physical < physical_end && ret);
+loop:
+					physical += map->stripe_len;
+					ret = get_raid56_logic_offset(physical,
+							num, map, &logical,
+							&stripe_logical);
+					logical += base;
+
+					if (ret && physical < physical_end) {
+						stripe_logical += base;
+						stripe_end = stripe_logical +
+								increment - 1;
+						ret = scrub_raid56_parity(sctx,
+							map, scrub_dev, ppath,
+							stripe_logical,
+							stripe_end);
+						if (ret)
+							goto out;
+						goto loop;
+					}
 				} else {
 					physical += map->stripe_len;
 					logical += increment;
@@ -2763,6 +3343,7 @@ out:
 
 	blk_finish_plug(&plug);
 	btrfs_free_path(path);
+	btrfs_free_path(ppath);
 	return ret < 0 ? ret : 0;
 }