1 files changed, 384 insertions, 184 deletions

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index b0251eb1239f..6f1e4c984b94 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -18,6 +18,7 @@
 
 #include <linux/blkdev.h>
 #include <linux/ratelimit.h>
+#include <linux/sched/mm.h>
 #include "ctree.h"
 #include "volumes.h"
 #include "disk-io.h"
@@ -64,7 +65,7 @@ struct scrub_ctx;
 #define SCRUB_MAX_PAGES_PER_BLOCK	16	/* 64k per node/leaf/sector */
 
 struct scrub_recover {
-	atomic_t		refs;
+	refcount_t		refs;
 	struct btrfs_bio	*bbio;
 	u64			map_length;
 };
@@ -95,7 +96,7 @@ struct scrub_bio {
 	struct scrub_ctx	*sctx;
 	struct btrfs_device	*dev;
 	struct bio		*bio;
-	int			err;
+	blk_status_t		status;
 	u64			logical;
 	u64			physical;
 #if SCRUB_PAGES_PER_WR_BIO >= SCRUB_PAGES_PER_RD_BIO
@@ -112,7 +113,7 @@ struct scrub_block {
 	struct scrub_page	*pagev[SCRUB_MAX_PAGES_PER_BLOCK];
 	int			page_count;
 	atomic_t		outstanding_pages;
-	atomic_t		refs; /* free mem on transition to zero */
+	refcount_t		refs; /* free mem on transition to zero */
 	struct scrub_ctx	*sctx;
 	struct scrub_parity	*sparity;
 	struct {
@@ -140,9 +141,9 @@ struct scrub_parity {
 
 	int			nsectors;
 
-	int			stripe_len;
+	u64			stripe_len;
 
-	atomic_t		refs;
+	refcount_t		refs;
 
 	struct list_head	spages;
 
@@ -161,14 +162,6 @@ struct scrub_parity {
 	unsigned long		bitmap[0];
 };
 
-struct scrub_wr_ctx {
-	struct scrub_bio *wr_curr_bio;
-	struct btrfs_device *tgtdev;
-	int pages_per_wr_bio; /* <= SCRUB_PAGES_PER_WR_BIO */
-	atomic_t flush_all_writes;
-	struct mutex wr_lock;
-};
-
 struct scrub_ctx {
 	struct scrub_bio	*bios[SCRUB_BIOS_PER_SCTX];
 	struct btrfs_fs_info	*fs_info;
@@ -183,11 +176,14 @@ struct scrub_ctx {
 	atomic_t		cancel_req;
 	int			readonly;
 	int			pages_per_rd_bio;
-	u32			sectorsize;
-	u32			nodesize;
 
 	int			is_dev_replace;
-	struct scrub_wr_ctx	wr_ctx;
+
+	struct scrub_bio        *wr_curr_bio;
+	struct mutex            wr_lock;
+	int                     pages_per_wr_bio; /* <= SCRUB_PAGES_PER_WR_BIO */
+	atomic_t                flush_all_writes;
+	struct btrfs_device     *wr_tgtdev;
 
 	/*
 	 * statistics
@@ -202,7 +198,7 @@ struct scrub_ctx {
 	 * doesn't free the scrub context before or while the workers are
 	 * doing the wakeup() call.
 	 */
-	atomic_t                refs;
+	refcount_t              refs;
 };
 
 struct scrub_fixup_nodatasum {
@@ -240,6 +236,13 @@ struct scrub_warning {
 	struct btrfs_device	*dev;
 };
 
+struct full_stripe_lock {
+	struct rb_node node;
+	u64 logical;
+	u64 refs;
+	struct mutex mutex;
+};
+
 static void scrub_pending_bio_inc(struct scrub_ctx *sctx);
 static void scrub_pending_bio_dec(struct scrub_ctx *sctx);
 static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx);
@@ -282,10 +285,6 @@ static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
 			       u64 *extent_physical,
 			       struct btrfs_device **extent_dev,
 			       int *extent_mirror_num);
-static int scrub_setup_wr_ctx(struct scrub_wr_ctx *wr_ctx,
-			      struct btrfs_device *dev,
-			      int is_dev_replace);
-static void scrub_free_wr_ctx(struct scrub_wr_ctx *wr_ctx);
 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
 				    struct scrub_page *spage);
 static void scrub_wr_submit(struct scrub_ctx *sctx);
@@ -305,7 +304,7 @@ static void scrub_put_ctx(struct scrub_ctx *sctx);
 
 static void scrub_pending_bio_inc(struct scrub_ctx *sctx)
 {
-	atomic_inc(&sctx->refs);
+	refcount_inc(&sctx->refs);
 	atomic_inc(&sctx->bios_in_flight);
 }
 
@@ -349,6 +348,222 @@ static void scrub_blocked_if_needed(struct btrfs_fs_info *fs_info)
 }
 
 /*
+ * Insert new full stripe lock into full stripe locks tree
+ *
+ * Return pointer to existing or newly inserted full_stripe_lock structure if
+ * everything works well.
+ * Return ERR_PTR(-ENOMEM) if we failed to allocate memory
+ *
+ * NOTE: caller must hold full_stripe_locks_root->lock before calling this
+ * function
+ */
+static struct full_stripe_lock *insert_full_stripe_lock(
+		struct btrfs_full_stripe_locks_tree *locks_root,
+		u64 fstripe_logical)
+{
+	struct rb_node **p;
+	struct rb_node *parent = NULL;
+	struct full_stripe_lock *entry;
+	struct full_stripe_lock *ret;
+
+	WARN_ON(!mutex_is_locked(&locks_root->lock));
+
+	p = &locks_root->root.rb_node;
+	while (*p) {
+		parent = *p;
+		entry = rb_entry(parent, struct full_stripe_lock, node);
+		if (fstripe_logical < entry->logical) {
+			p = &(*p)->rb_left;
+		} else if (fstripe_logical > entry->logical) {
+			p = &(*p)->rb_right;
+		} else {
+			entry->refs++;
+			return entry;
+		}
+	}
+
+	/* Insert new lock */
+	ret = kmalloc(sizeof(*ret), GFP_KERNEL);
+	if (!ret)
+		return ERR_PTR(-ENOMEM);
+	ret->logical = fstripe_logical;
+	ret->refs = 1;
+	mutex_init(&ret->mutex);
+
+	rb_link_node(&ret->node, parent, p);
+	rb_insert_color(&ret->node, &locks_root->root);
+	return ret;
+}
+
+/*
+ * Search for a full stripe lock of a block group
+ *
+ * Return pointer to existing full stripe lock if found
+ * Return NULL if not found
+ */
+static struct full_stripe_lock *search_full_stripe_lock(
+		struct btrfs_full_stripe_locks_tree *locks_root,
+		u64 fstripe_logical)
+{
+	struct rb_node *node;
+	struct full_stripe_lock *entry;
+
+	WARN_ON(!mutex_is_locked(&locks_root->lock));
+
+	node = locks_root->root.rb_node;
+	while (node) {
+		entry = rb_entry(node, struct full_stripe_lock, node);
+		if (fstripe_logical < entry->logical)
+			node = node->rb_left;
+		else if (fstripe_logical > entry->logical)
+			node = node->rb_right;
+		else
+			return entry;
+	}
+	return NULL;
+}
+
+/*
+ * Helper to get full stripe logical from a normal bytenr.
+ *
+ * Caller must ensure @cache is a RAID56 block group.
+ */
+static u64 get_full_stripe_logical(struct btrfs_block_group_cache *cache,
+				   u64 bytenr)
+{
+	u64 ret;
+
+	/*
+	 * Due to chunk item size limit, full stripe length should not be
+	 * larger than U32_MAX. Just a sanity check here.
+	 */
+	WARN_ON_ONCE(cache->full_stripe_len >= U32_MAX);
+
+	/*
+	 * round_down() can only handle power of 2, while RAID56 full
+	 * stripe length can be 64KiB * n, so we need to manually round down.
+	 */
+	ret = div64_u64(bytenr - cache->key.objectid, cache->full_stripe_len) *
+		cache->full_stripe_len + cache->key.objectid;
+	return ret;
+}
+
+/*
+ * Lock a full stripe to avoid concurrency of recovery and read
+ *
+ * It's only used for profiles with parities (RAID5/6), for other profiles it
+ * does nothing.
+ *
+ * Return 0 if we locked full stripe covering @bytenr, with a mutex held.
+ * So caller must call unlock_full_stripe() at the same context.
+ *
+ * Return <0 if encounters error.
+ */
+static int lock_full_stripe(struct btrfs_fs_info *fs_info, u64 bytenr,
+			    bool *locked_ret)
+{
+	struct btrfs_block_group_cache *bg_cache;
+	struct btrfs_full_stripe_locks_tree *locks_root;
+	struct full_stripe_lock *existing;
+	u64 fstripe_start;
+	int ret = 0;
+
+	*locked_ret = false;
+	bg_cache = btrfs_lookup_block_group(fs_info, bytenr);
+	if (!bg_cache) {
+		ASSERT(0);
+		return -ENOENT;
+	}
+
+	/* Profiles not based on parity don't need full stripe lock */
+	if (!(bg_cache->flags & BTRFS_BLOCK_GROUP_RAID56_MASK))
+		goto out;
+	locks_root = &bg_cache->full_stripe_locks_root;
+
+	fstripe_start = get_full_stripe_logical(bg_cache, bytenr);
+
+	/* Now insert the full stripe lock */
+	mutex_lock(&locks_root->lock);
+	existing = insert_full_stripe_lock(locks_root, fstripe_start);
+	mutex_unlock(&locks_root->lock);
+	if (IS_ERR(existing)) {
+		ret = PTR_ERR(existing);
+		goto out;
+	}
+	mutex_lock(&existing->mutex);
+	*locked_ret = true;
+out:
+	btrfs_put_block_group(bg_cache);
+	return ret;
+}
+
+/*
+ * Unlock a full stripe.
+ *
+ * NOTE: Caller must ensure it's the same context calling corresponding
+ * lock_full_stripe().
+ *
+ * Return 0 if we unlock full stripe without problem.
+ * Return <0 for error
+ */
+static int unlock_full_stripe(struct btrfs_fs_info *fs_info, u64 bytenr,
+			      bool locked)
+{
+	struct btrfs_block_group_cache *bg_cache;
+	struct btrfs_full_stripe_locks_tree *locks_root;
+	struct full_stripe_lock *fstripe_lock;
+	u64 fstripe_start;
+	bool freeit = false;
+	int ret = 0;
+
+	/* If we didn't acquire full stripe lock, no need to continue */
+	if (!locked)
+		return 0;
+
+	bg_cache = btrfs_lookup_block_group(fs_info, bytenr);
+	if (!bg_cache) {
+		ASSERT(0);
+		return -ENOENT;
+	}
+	if (!(bg_cache->flags & BTRFS_BLOCK_GROUP_RAID56_MASK))
+		goto out;
+
+	locks_root = &bg_cache->full_stripe_locks_root;
+	fstripe_start = get_full_stripe_logical(bg_cache, bytenr);
+
+	mutex_lock(&locks_root->lock);
+	fstripe_lock = search_full_stripe_lock(locks_root, fstripe_start);
+	/* Unpaired unlock_full_stripe() detected */
+	if (!fstripe_lock) {
+		WARN_ON(1);
+		ret = -ENOENT;
+		mutex_unlock(&locks_root->lock);
+		goto out;
+	}
+
+	if (fstripe_lock->refs == 0) {
+		WARN_ON(1);
+		btrfs_warn(fs_info, "full stripe lock at %llu refcount underflow",
+			fstripe_lock->logical);
+	} else {
+		fstripe_lock->refs--;
+	}
+
+	if (fstripe_lock->refs == 0) {
+		rb_erase(&fstripe_lock->node, &locks_root->root);
+		freeit = true;
+	}
+	mutex_unlock(&locks_root->lock);
+
+	mutex_unlock(&fstripe_lock->mutex);
+	if (freeit)
+		kfree(fstripe_lock);
+out:
+	btrfs_put_block_group(bg_cache);
+	return ret;
+}
+
+/*
  * used for workers that require transaction commits (i.e., for the
  * NOCOW case)
  */
@@ -356,7 +571,7 @@ static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx)
 {
 	struct btrfs_fs_info *fs_info = sctx->fs_info;
 
-	atomic_inc(&sctx->refs);
+	refcount_inc(&sctx->refs);
 	/*
 	 * increment scrubs_running to prevent cancel requests from
 	 * completing as long as a worker is running. we must also
@@ -420,8 +635,6 @@ static noinline_for_stack void scrub_free_ctx(struct scrub_ctx *sctx)
 	if (!sctx)
 		return;
 
-	scrub_free_wr_ctx(&sctx->wr_ctx);
-
 	/* this can happen when scrub is cancelled */
 	if (sctx->curr != -1) {
 		struct scrub_bio *sbio = sctx->bios[sctx->curr];
@@ -441,13 +654,14 @@ static noinline_for_stack void scrub_free_ctx(struct scrub_ctx *sctx)
 		kfree(sbio);
 	}
 
+	kfree(sctx->wr_curr_bio);
 	scrub_free_csums(sctx);
 	kfree(sctx);
 }
 
 static void scrub_put_ctx(struct scrub_ctx *sctx)
 {
-	if (atomic_dec_and_test(&sctx->refs))
+	if (refcount_dec_and_test(&sctx->refs))
 		scrub_free_ctx(sctx);
 }
 
@@ -457,12 +671,11 @@ struct scrub_ctx *scrub_setup_ctx(struct btrfs_device *dev, int is_dev_replace)
 	struct scrub_ctx *sctx;
 	int		i;
 	struct btrfs_fs_info *fs_info = dev->fs_info;
-	int ret;
 
 	sctx = kzalloc(sizeof(*sctx), GFP_KERNEL);
 	if (!sctx)
 		goto nomem;
-	atomic_set(&sctx->refs, 1);
+	refcount_set(&sctx->refs, 1);
 	sctx->is_dev_replace = is_dev_replace;
 	sctx->pages_per_rd_bio = SCRUB_PAGES_PER_RD_BIO;
 	sctx->curr = -1;
@@ -487,8 +700,6 @@ struct scrub_ctx *scrub_setup_ctx(struct btrfs_device *dev, int is_dev_replace)
 			sctx->bios[i]->next_free = -1;
 	}
 	sctx->first_free = 0;
-	sctx->nodesize = fs_info->nodesize;
-	sctx->sectorsize = fs_info->sectorsize;
 	atomic_set(&sctx->bios_in_flight, 0);
 	atomic_set(&sctx->workers_pending, 0);
 	atomic_set(&sctx->cancel_req, 0);
@@ -499,12 +710,16 @@ struct scrub_ctx *scrub_setup_ctx(struct btrfs_device *dev, int is_dev_replace)
 	spin_lock_init(&sctx->stat_lock);
 	init_waitqueue_head(&sctx->list_wait);
 
-	ret = scrub_setup_wr_ctx(&sctx->wr_ctx,
-				 fs_info->dev_replace.tgtdev, is_dev_replace);
-	if (ret) {
-		scrub_free_ctx(sctx);
-		return ERR_PTR(ret);
+	WARN_ON(sctx->wr_curr_bio != NULL);
+	mutex_init(&sctx->wr_lock);
+	sctx->wr_curr_bio = NULL;
+	if (is_dev_replace) {
+		WARN_ON(!fs_info->dev_replace.tgtdev);
+		sctx->pages_per_wr_bio = SCRUB_PAGES_PER_WR_BIO;
+		sctx->wr_tgtdev = fs_info->dev_replace.tgtdev;
+		atomic_set(&sctx->flush_all_writes, 0);
 	}
+
 	return sctx;
 
 nomem:
@@ -519,6 +734,7 @@ static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
 	u32 nlink;
 	int ret;
 	int i;
+	unsigned nofs_flag;
 	struct extent_buffer *eb;
 	struct btrfs_inode_item *inode_item;
 	struct scrub_warning *swarn = warn_ctx;
@@ -557,7 +773,14 @@ static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
 	nlink = btrfs_inode_nlink(eb, inode_item);
 	btrfs_release_path(swarn->path);
 
+	/*
+	 * init_path might indirectly call vmalloc, or use GFP_KERNEL. Scrub
+	 * uses GFP_NOFS in this context, so we keep it consistent but it does
+	 * not seem to be strictly necessary.
+	 */
+	nofs_flag = memalloc_nofs_save();
 	ipath = init_ipath(4096, local_root, swarn->path);
+	memalloc_nofs_restore(nofs_flag);
 	if (IS_ERR(ipath)) {
 		ret = PTR_ERR(ipath);
 		ipath = NULL;
@@ -731,7 +954,7 @@ static int scrub_fixup_readpage(u64 inum, u64 offset, u64 root, void *fixup_ctx)
 			ret = -EIO;
 			goto out;
 		}
-		ret = repair_io_failure(BTRFS_I(inode), offset, PAGE_SIZE,
+		ret = repair_io_failure(fs_info, inum, offset, PAGE_SIZE,
 					fixup->logical, page,
 					offset - page_offset(page),
 					fixup->mirror_num);
@@ -857,12 +1080,14 @@ out:
 
 static inline void scrub_get_recover(struct scrub_recover *recover)
 {
-	atomic_inc(&recover->refs);
+	refcount_inc(&recover->refs);
 }
 
-static inline void scrub_put_recover(struct scrub_recover *recover)
+static inline void scrub_put_recover(struct btrfs_fs_info *fs_info,
+				     struct scrub_recover *recover)
 {
-	if (atomic_dec_and_test(&recover->refs)) {
+	if (refcount_dec_and_test(&recover->refs)) {
+		btrfs_bio_counter_dec(fs_info);
 		btrfs_put_bbio(recover->bbio);
 		kfree(recover);
 	}
@@ -892,6 +1117,7 @@ static int scrub_handle_errored_block(struct scrub_block *sblock_to_check)
 	int mirror_index;
 	int page_num;
 	int success;
+	bool full_stripe_locked;
 	static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
 				      DEFAULT_RATELIMIT_BURST);
 
@@ -917,6 +1143,24 @@ static int scrub_handle_errored_block(struct scrub_block *sblock_to_check)
 	have_csum = sblock_to_check->pagev[0]->have_csum;
 	dev = sblock_to_check->pagev[0]->dev;
 
+	/*
+	 * For RAID5/6, race can happen for a different device scrub thread.
+	 * For data corruption, Parity and Data threads will both try
+	 * to recovery the data.
+	 * Race can lead to doubly added csum error, or even unrecoverable
+	 * error.
+	 */
+	ret = lock_full_stripe(fs_info, logical, &full_stripe_locked);
+	if (ret < 0) {
+		spin_lock(&sctx->stat_lock);
+		if (ret == -ENOMEM)
+			sctx->stat.malloc_errors++;
+		sctx->stat.read_errors++;
+		sctx->stat.uncorrectable_errors++;
+		spin_unlock(&sctx->stat_lock);
+		return ret;
+	}
+
 	if (sctx->is_dev_replace && !is_metadata && !have_csum) {
 		sblocks_for_recheck = NULL;
 		goto nodatasum_case;
@@ -1241,7 +1485,7 @@ out:
 				sblock->pagev[page_index]->sblock = NULL;
 				recover = sblock->pagev[page_index]->recover;
 				if (recover) {
-					scrub_put_recover(recover);
+					scrub_put_recover(fs_info, recover);
 					sblock->pagev[page_index]->recover =
 									NULL;
 				}
@@ -1251,6 +1495,9 @@ out:
 		kfree(sblocks_for_recheck);
 	}
 
+	ret = unlock_full_stripe(fs_info, logical, full_stripe_locked);
+	if (ret < 0)
+		return ret;
 	return 0;
 }
 
@@ -1330,20 +1577,23 @@ static int scrub_setup_recheck_block(struct scrub_block *original_sblock,
 		 * with a length of PAGE_SIZE, each returned stripe
 		 * represents one mirror
 		 */
+		btrfs_bio_counter_inc_blocked(fs_info);
 		ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS,
-				logical, &mapped_length, &bbio, 0, 1);
+				logical, &mapped_length, &bbio);
 		if (ret || !bbio || mapped_length < sublen) {
 			btrfs_put_bbio(bbio);
+			btrfs_bio_counter_dec(fs_info);
 			return -EIO;
 		}
 
 		recover = kzalloc(sizeof(struct scrub_recover), GFP_NOFS);
 		if (!recover) {
 			btrfs_put_bbio(bbio);
+			btrfs_bio_counter_dec(fs_info);
 			return -ENOMEM;
 		}
 
-		atomic_set(&recover->refs, 1);
+		refcount_set(&recover->refs, 1);
 		recover->bbio = bbio;
 		recover->map_length = mapped_length;
 
@@ -1365,7 +1615,7 @@ leave_nomem:
 				spin_lock(&sctx->stat_lock);
 				sctx->stat.malloc_errors++;
 				spin_unlock(&sctx->stat_lock);
-				scrub_put_recover(recover);
+				scrub_put_recover(fs_info, recover);
 				return -ENOMEM;
 			}
 			scrub_page_get(page);
@@ -1407,7 +1657,7 @@ leave_nomem:
 			scrub_get_recover(recover);
 			page->recover = recover;
 		}
-		scrub_put_recover(recover);
+		scrub_put_recover(fs_info, recover);
 		length -= sublen;
 		logical += sublen;
 		page_index++;
@@ -1418,14 +1668,14 @@ leave_nomem:
 
 struct scrub_bio_ret {
 	struct completion event;
-	int error;
+	blk_status_t status;
 };
 
 static void scrub_bio_wait_endio(struct bio *bio)
 {
 	struct scrub_bio_ret *ret = bio->bi_private;
 
-	ret->error = bio->bi_error;
+	ret->status = bio->bi_status;
 	complete(&ret->event);
 }
 
@@ -1443,7 +1693,7 @@ static int scrub_submit_raid56_bio_wait(struct btrfs_fs_info *fs_info,
 	int ret;
 
 	init_completion(&done.event);
-	done.error = 0;
+	done.status = 0;
 	bio->bi_iter.bi_sector = page->logical >> 9;
 	bio->bi_private = &done;
 	bio->bi_end_io = scrub_bio_wait_endio;
@@ -1455,7 +1705,7 @@ static int scrub_submit_raid56_bio_wait(struct btrfs_fs_info *fs_info,
 		return ret;
 
 	wait_for_completion(&done.event);
-	if (done.error)
+	if (done.status)
 		return -EIO;
 
 	return 0;
@@ -1487,24 +1737,23 @@ static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
 		}
 
 		WARN_ON(!page->page);
-		bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
-		if (!bio) {
-			page->io_error = 1;
-			sblock->no_io_error_seen = 0;
-			continue;
-		}
+		bio = btrfs_io_bio_alloc(1);
 		bio->bi_bdev = page->dev->bdev;
 
 		bio_add_page(bio, page->page, PAGE_SIZE, 0);
 		if (!retry_failed_mirror && scrub_is_page_on_raid56(page)) {
-			if (scrub_submit_raid56_bio_wait(fs_info, bio, page))
+			if (scrub_submit_raid56_bio_wait(fs_info, bio, page)) {
+				page->io_error = 1;
 				sblock->no_io_error_seen = 0;
+			}
 		} else {
 			bio->bi_iter.bi_sector = page->physical >> 9;
 			bio_set_op_attrs(bio, REQ_OP_READ, 0);
 
-			if (btrfsic_submit_bio_wait(bio))
+			if (btrfsic_submit_bio_wait(bio)) {
+				page->io_error = 1;
 				sblock->no_io_error_seen = 0;
+			}
 		}
 
 		bio_put(bio);
@@ -1576,9 +1825,7 @@ static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
 			return -EIO;
 		}
 
-		bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
-		if (!bio)
-			return -EIO;
+		bio = btrfs_io_bio_alloc(1);
 		bio->bi_bdev = page_bad->dev->bdev;
 		bio->bi_iter.bi_sector = page_bad->physical >> 9;
 		bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
@@ -1634,7 +1881,7 @@ static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
 	if (spage->io_error) {
 		void *mapped_buffer = kmap_atomic(spage->page);
 
-		memset(mapped_buffer, 0, PAGE_SIZE);
+		clear_page(mapped_buffer);
 		flush_dcache_page(spage->page);
 		kunmap_atomic(mapped_buffer);
 	}
@@ -1644,37 +1891,31 @@ static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
 				    struct scrub_page *spage)
 {
-	struct scrub_wr_ctx *wr_ctx = &sctx->wr_ctx;
 	struct scrub_bio *sbio;
 	int ret;
 
-	mutex_lock(&wr_ctx->wr_lock);
+	mutex_lock(&sctx->wr_lock);
 again:
-	if (!wr_ctx->wr_curr_bio) {
-		wr_ctx->wr_curr_bio = kzalloc(sizeof(*wr_ctx->wr_curr_bio),
+	if (!sctx->wr_curr_bio) {
+		sctx->wr_curr_bio = kzalloc(sizeof(*sctx->wr_curr_bio),
 					      GFP_KERNEL);
-		if (!wr_ctx->wr_curr_bio) {
-			mutex_unlock(&wr_ctx->wr_lock);
+		if (!sctx->wr_curr_bio) {
+			mutex_unlock(&sctx->wr_lock);
 			return -ENOMEM;
 		}
-		wr_ctx->wr_curr_bio->sctx = sctx;
-		wr_ctx->wr_curr_bio->page_count = 0;
+		sctx->wr_curr_bio->sctx = sctx;
+		sctx->wr_curr_bio->page_count = 0;
 	}
-	sbio = wr_ctx->wr_curr_bio;
+	sbio = sctx->wr_curr_bio;
 	if (sbio->page_count == 0) {
 		struct bio *bio;
 
 		sbio->physical = spage->physical_for_dev_replace;
 		sbio->logical = spage->logical;
-		sbio->dev = wr_ctx->tgtdev;
+		sbio->dev = sctx->wr_tgtdev;
 		bio = sbio->bio;
 		if (!bio) {
-			bio = btrfs_io_bio_alloc(GFP_KERNEL,
-					wr_ctx->pages_per_wr_bio);
-			if (!bio) {
-				mutex_unlock(&wr_ctx->wr_lock);
-				return -ENOMEM;
-			}
+			bio = btrfs_io_bio_alloc(sctx->pages_per_wr_bio);
 			sbio->bio = bio;
 		}
 
@@ -1683,7 +1924,7 @@ again:
 		bio->bi_bdev = sbio->dev->bdev;
 		bio->bi_iter.bi_sector = sbio->physical >> 9;
 		bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
-		sbio->err = 0;
+		sbio->status = 0;
 	} else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
 		   spage->physical_for_dev_replace ||
 		   sbio->logical + sbio->page_count * PAGE_SIZE !=
@@ -1697,7 +1938,7 @@ again:
 		if (sbio->page_count < 1) {
 			bio_put(sbio->bio);
 			sbio->bio = NULL;
-			mutex_unlock(&wr_ctx->wr_lock);
+			mutex_unlock(&sctx->wr_lock);
 			return -EIO;
 		}
 		scrub_wr_submit(sctx);
@@ -1707,23 +1948,22 @@ again:
 	sbio->pagev[sbio->page_count] = spage;
 	scrub_page_get(spage);
 	sbio->page_count++;
-	if (sbio->page_count == wr_ctx->pages_per_wr_bio)
+	if (sbio->page_count == sctx->pages_per_wr_bio)
 		scrub_wr_submit(sctx);
-	mutex_unlock(&wr_ctx->wr_lock);
+	mutex_unlock(&sctx->wr_lock);
 
 	return 0;
 }
 
 static void scrub_wr_submit(struct scrub_ctx *sctx)
 {
-	struct scrub_wr_ctx *wr_ctx = &sctx->wr_ctx;
 	struct scrub_bio *sbio;
 
-	if (!wr_ctx->wr_curr_bio)
+	if (!sctx->wr_curr_bio)
 		return;
 
-	sbio = wr_ctx->wr_curr_bio;
-	wr_ctx->wr_curr_bio = NULL;
+	sbio = sctx->wr_curr_bio;
+	sctx->wr_curr_bio = NULL;
 	WARN_ON(!sbio->bio->bi_bdev);
 	scrub_pending_bio_inc(sctx);
 	/* process all writes in a single worker thread. Then the block layer
@@ -1738,7 +1978,7 @@ static void scrub_wr_bio_end_io(struct bio *bio)
 	struct scrub_bio *sbio = bio->bi_private;
 	struct btrfs_fs_info *fs_info = sbio->dev->fs_info;
 
-	sbio->err = bio->bi_error;
+	sbio->status = bio->bi_status;
 	sbio->bio = bio;
 
 	btrfs_init_work(&sbio->work, btrfs_scrubwrc_helper,
@@ -1753,7 +1993,7 @@ static void scrub_wr_bio_end_io_worker(struct btrfs_work *work)
 	int i;
 
 	WARN_ON(sbio->page_count > SCRUB_PAGES_PER_WR_BIO);
-	if (sbio->err) {
+	if (sbio->status) {
 		struct btrfs_dev_replace *dev_replace =
 			&sbio->sctx->fs_info->dev_replace;
 
@@ -1827,7 +2067,7 @@ static int scrub_checksum_data(struct scrub_block *sblock)
 	page = sblock->pagev[0]->page;
 	buffer = kmap_atomic(page);
 
-	len = sctx->sectorsize;
+	len = sctx->fs_info->sectorsize;
 	index = 0;
 	for (;;) {
 		u64 l = min_t(u64, len, PAGE_SIZE);
@@ -1892,7 +2132,7 @@ static int scrub_checksum_tree_block(struct scrub_block *sblock)
 		   BTRFS_UUID_SIZE))
 		sblock->header_error = 1;
 
-	len = sctx->nodesize - BTRFS_CSUM_SIZE;
+	len = sctx->fs_info->nodesize - BTRFS_CSUM_SIZE;
 	mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
 	p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
 	index = 0;
@@ -1998,12 +2238,12 @@ static int scrub_checksum_super(struct scrub_block *sblock)
 
 static void scrub_block_get(struct scrub_block *sblock)
 {
-	atomic_inc(&sblock->refs);
+	refcount_inc(&sblock->refs);
 }
 
 static void scrub_block_put(struct scrub_block *sblock)
 {
-	if (atomic_dec_and_test(&sblock->refs)) {
+	if (refcount_dec_and_test(&sblock->refs)) {
 		int i;
 
 		if (sblock->sparity)
@@ -2075,10 +2315,7 @@ again:
 		sbio->dev = spage->dev;
 		bio = sbio->bio;
 		if (!bio) {
-			bio = btrfs_io_bio_alloc(GFP_KERNEL,
-					sctx->pages_per_rd_bio);
-			if (!bio)
-				return -ENOMEM;
+			bio = btrfs_io_bio_alloc(sctx->pages_per_rd_bio);
 			sbio->bio = bio;
 		}
 
@@ -2087,7 +2324,7 @@ again:
 		bio->bi_bdev = sbio->dev->bdev;
 		bio->bi_iter.bi_sector = sbio->physical >> 9;
 		bio_set_op_attrs(bio, REQ_OP_READ, 0);
-		sbio->err = 0;
+		sbio->status = 0;
 	} else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
 		   spage->physical ||
 		   sbio->logical + sbio->page_count * PAGE_SIZE !=
@@ -2123,7 +2360,7 @@ static void scrub_missing_raid56_end_io(struct bio *bio)
 	struct scrub_block *sblock = bio->bi_private;
 	struct btrfs_fs_info *fs_info = sblock->sctx->fs_info;
 
-	if (bio->bi_error)
+	if (bio->bi_status)
 		sblock->no_io_error_seen = 0;
 
 	bio_put(bio);
@@ -2166,10 +2403,10 @@ static void scrub_missing_raid56_worker(struct btrfs_work *work)
 	scrub_block_put(sblock);
 
 	if (sctx->is_dev_replace &&
-	    atomic_read(&sctx->wr_ctx.flush_all_writes)) {
-		mutex_lock(&sctx->wr_ctx.wr_lock);
+	    atomic_read(&sctx->flush_all_writes)) {
+		mutex_lock(&sctx->wr_lock);
 		scrub_wr_submit(sctx);
-		mutex_unlock(&sctx->wr_ctx.wr_lock);
+		mutex_unlock(&sctx->wr_lock);
 	}
 
 	scrub_pending_bio_dec(sctx);
@@ -2187,8 +2424,9 @@ static void scrub_missing_raid56_pages(struct scrub_block *sblock)
 	int ret;
 	int i;
 
+	btrfs_bio_counter_inc_blocked(fs_info);
 	ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS, logical,
-			&length, &bbio, 0, 1);
+			&length, &bbio);
 	if (ret || !bbio || !bbio->raid_map)
 		goto bbio_out;
 
@@ -2203,10 +2441,7 @@ static void scrub_missing_raid56_pages(struct scrub_block *sblock)
 		goto bbio_out;
 	}
 
-	bio = btrfs_io_bio_alloc(GFP_NOFS, 0);
-	if (!bio)
-		goto bbio_out;
-
+	bio = btrfs_io_bio_alloc(0);
 	bio->bi_iter.bi_sector = logical >> 9;
 	bio->bi_private = sblock;
 	bio->bi_end_io = scrub_missing_raid56_end_io;
@@ -2231,6 +2466,7 @@ static void scrub_missing_raid56_pages(struct scrub_block *sblock)
 rbio_out:
 	bio_put(bio);
 bbio_out:
+	btrfs_bio_counter_dec(fs_info);
 	btrfs_put_bbio(bbio);
 	spin_lock(&sctx->stat_lock);
 	sctx->stat.malloc_errors++;
@@ -2255,7 +2491,7 @@ static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
 
 	/* one ref inside this function, plus one for each page added to
 	 * a bio later on */
-	atomic_set(&sblock->refs, 1);
+	refcount_set(&sblock->refs, 1);
 	sblock->sctx = sctx;
 	sblock->no_io_error_seen = 1;
 
@@ -2332,7 +2568,7 @@ static void scrub_bio_end_io(struct bio *bio)
 	struct scrub_bio *sbio = bio->bi_private;
 	struct btrfs_fs_info *fs_info = sbio->dev->fs_info;
 
-	sbio->err = bio->bi_error;
+	sbio->status = bio->bi_status;
 	sbio->bio = bio;
 
 	btrfs_queue_work(fs_info->scrub_workers, &sbio->work);
@@ -2345,7 +2581,7 @@ static void scrub_bio_end_io_worker(struct btrfs_work *work)
 	int i;
 
 	BUG_ON(sbio->page_count > SCRUB_PAGES_PER_RD_BIO);
-	if (sbio->err) {
+	if (sbio->status) {
 		for (i = 0; i < sbio->page_count; i++) {
 			struct scrub_page *spage = sbio->pagev[i];
 
@@ -2372,10 +2608,10 @@ static void scrub_bio_end_io_worker(struct btrfs_work *work)
 	spin_unlock(&sctx->list_lock);
 
 	if (sctx->is_dev_replace &&
-	    atomic_read(&sctx->wr_ctx.flush_all_writes)) {
-		mutex_lock(&sctx->wr_ctx.wr_lock);
+	    atomic_read(&sctx->flush_all_writes)) {
+		mutex_lock(&sctx->wr_lock);
 		scrub_wr_submit(sctx);
-		mutex_unlock(&sctx->wr_ctx.wr_lock);
+		mutex_unlock(&sctx->wr_lock);
 	}
 
 	scrub_pending_bio_dec(sctx);
@@ -2385,7 +2621,7 @@ static inline void __scrub_mark_bitmap(struct scrub_parity *sparity,
 				       unsigned long *bitmap,
 				       u64 start, u64 len)
 {
-	u32 offset;
+	u64 offset;
 	int nsectors;
 	int sectorsize = sparity->sctx->fs_info->sectorsize;
 
@@ -2395,8 +2631,8 @@ static inline void __scrub_mark_bitmap(struct scrub_parity *sparity,
 	}
 
 	start -= sparity->logic_start;
-	start = div_u64_rem(start, sparity->stripe_len, &offset);
-	offset /= sectorsize;
+	start = div64_u64_rem(start, sparity->stripe_len, &offset);
+	offset = div_u64(offset, sectorsize);
 	nsectors = (int)len / sectorsize;
 
 	if (offset + nsectors <= sparity->nsectors) {
@@ -2470,8 +2706,8 @@ static int scrub_find_csum(struct scrub_ctx *sctx, u64 logical, u8 *csum)
 	if (!sum)
 		return 0;
 
-	index = ((u32)(logical - sum->bytenr)) / sctx->sectorsize;
-	num_sectors = sum->len / sctx->sectorsize;
+	index = ((u32)(logical - sum->bytenr)) / sctx->fs_info->sectorsize;
+	num_sectors = sum->len / sctx->fs_info->sectorsize;
 	memcpy(csum, sum->sums + index, sctx->csum_size);
 	if (index == num_sectors - 1) {
 		list_del(&sum->list);
@@ -2490,19 +2726,19 @@ static int scrub_extent(struct scrub_ctx *sctx, u64 logical, u64 len,
 	u32 blocksize;
 
 	if (flags & BTRFS_EXTENT_FLAG_DATA) {
-		blocksize = sctx->sectorsize;
+		blocksize = sctx->fs_info->sectorsize;
 		spin_lock(&sctx->stat_lock);
 		sctx->stat.data_extents_scrubbed++;
 		sctx->stat.data_bytes_scrubbed += len;
 		spin_unlock(&sctx->stat_lock);
 	} else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
-		blocksize = sctx->nodesize;
+		blocksize = sctx->fs_info->nodesize;
 		spin_lock(&sctx->stat_lock);
 		sctx->stat.tree_extents_scrubbed++;
 		sctx->stat.tree_bytes_scrubbed += len;
 		spin_unlock(&sctx->stat_lock);
 	} else {
-		blocksize = sctx->sectorsize;
+		blocksize = sctx->fs_info->sectorsize;
 		WARN_ON(1);
 	}
 
@@ -2555,7 +2791,7 @@ static int scrub_pages_for_parity(struct scrub_parity *sparity,
 
 	/* one ref inside this function, plus one for each page added to
 	 * a bio later on */
-	atomic_set(&sblock->refs, 1);
+	refcount_set(&sblock->refs, 1);
 	sblock->sctx = sctx;
 	sblock->no_io_error_seen = 1;
 	sblock->sparity = sparity;
@@ -2636,11 +2872,11 @@ static int scrub_extent_for_parity(struct scrub_parity *sparity,
 	}
 
 	if (flags & BTRFS_EXTENT_FLAG_DATA) {
-		blocksize = sctx->sectorsize;
+		blocksize = sctx->fs_info->sectorsize;
 	} else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
-		blocksize = sctx->nodesize;
+		blocksize = sctx->fs_info->nodesize;
 	} else {
-		blocksize = sctx->sectorsize;
+		blocksize = sctx->fs_info->sectorsize;
 		WARN_ON(1);
 	}
 
@@ -2694,7 +2930,7 @@ static int get_raid56_logic_offset(u64 physical, int num,
 	for (i = 0; i < nr_data_stripes(map); i++) {
 		*offset = last_offset + i * map->stripe_len;
 
-		stripe_nr = div_u64(*offset, map->stripe_len);
+		stripe_nr = div64_u64(*offset, map->stripe_len);
 		stripe_nr = div_u64(stripe_nr, nr_data_stripes(map));
 
 		/* Work out the disk rotation on this stripe-set */
@@ -2748,7 +2984,7 @@ static void scrub_parity_bio_endio(struct bio *bio)
 	struct scrub_parity *sparity = (struct scrub_parity *)bio->bi_private;
 	struct btrfs_fs_info *fs_info = sparity->sctx->fs_info;
 
-	if (bio->bi_error)
+	if (bio->bi_status)
 		bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
 			  sparity->nsectors);
 
@@ -2765,7 +3001,6 @@ static void scrub_parity_check_and_repair(struct scrub_parity *sparity)
 	struct btrfs_fs_info *fs_info = sctx->fs_info;
 	struct bio *bio;
 	struct btrfs_raid_bio *rbio;
-	struct scrub_page *spage;
 	struct btrfs_bio *bbio = NULL;
 	u64 length;
 	int ret;
@@ -2775,15 +3010,14 @@ static void scrub_parity_check_and_repair(struct scrub_parity *sparity)
 		goto out;
 
 	length = sparity->logic_end - sparity->logic_start;
+
+	btrfs_bio_counter_inc_blocked(fs_info);
 	ret = btrfs_map_sblock(fs_info, BTRFS_MAP_WRITE, sparity->logic_start,
-			       &length, &bbio, 0, 1);
+			       &length, &bbio);
 	if (ret || !bbio || !bbio->raid_map)
 		goto bbio_out;
 
-	bio = btrfs_io_bio_alloc(GFP_NOFS, 0);
-	if (!bio)
-		goto bbio_out;
-
+	bio = btrfs_io_bio_alloc(0);
 	bio->bi_iter.bi_sector = sparity->logic_start >> 9;
 	bio->bi_private = sparity;
 	bio->bi_end_io = scrub_parity_bio_endio;
@@ -2795,9 +3029,6 @@ static void scrub_parity_check_and_repair(struct scrub_parity *sparity)
 	if (!rbio)
 		goto rbio_out;
 
-	list_for_each_entry(spage, &sparity->spages, list)
-		raid56_add_scrub_pages(rbio, spage->page, spage->logical);
-
 	scrub_pending_bio_inc(sctx);
 	raid56_parity_submit_scrub_rbio(rbio);
 	return;
@@ -2805,6 +3036,7 @@ static void scrub_parity_check_and_repair(struct scrub_parity *sparity)
 rbio_out:
 	bio_put(bio);
 bbio_out:
+	btrfs_bio_counter_dec(fs_info);
 	btrfs_put_bbio(bbio);
 	bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap,
 		  sparity->nsectors);
@@ -2822,12 +3054,12 @@ static inline int scrub_calc_parity_bitmap_len(int nsectors)
 
 static void scrub_parity_get(struct scrub_parity *sparity)
 {
-	atomic_inc(&sparity->refs);
+	refcount_inc(&sparity->refs);
 }
 
 static void scrub_parity_put(struct scrub_parity *sparity)
 {
-	if (!atomic_dec_and_test(&sparity->refs))
+	if (!refcount_dec_and_test(&sparity->refs))
 		return;
 
 	scrub_parity_check_and_repair(sparity);
@@ -2879,7 +3111,7 @@ static noinline_for_stack int scrub_raid56_parity(struct scrub_ctx *sctx,
 	sparity->scrub_dev = sdev;
 	sparity->logic_start = logic_start;
 	sparity->logic_end = logic_end;
-	atomic_set(&sparity->refs, 1);
+	refcount_set(&sparity->refs, 1);
 	INIT_LIST_HEAD(&sparity->spages);
 	sparity->dbitmap = sparity->bitmap;
 	sparity->ebitmap = (void *)sparity->bitmap + bitmap_len;
@@ -3050,9 +3282,9 @@ out:
 						logic_end - logic_start);
 	scrub_parity_put(sparity);
 	scrub_submit(sctx);
-	mutex_lock(&sctx->wr_ctx.wr_lock);
+	mutex_lock(&sctx->wr_lock);
 	scrub_wr_submit(sctx);
-	mutex_unlock(&sctx->wr_ctx.wr_lock);
+	mutex_unlock(&sctx->wr_lock);
 
 	btrfs_release_path(path);
 	return ret < 0 ? ret : 0;
@@ -3098,7 +3330,7 @@ static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
 
 	physical = map->stripes[num].physical;
 	offset = 0;
-	nstripes = div_u64(length, map->stripe_len);
+	nstripes = div64_u64(length, map->stripe_len);
 	if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
 		offset = map->stripe_len * num;
 		increment = map->stripe_len * map->num_stripes;
@@ -3208,14 +3440,14 @@ static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
 		 */
 		if (atomic_read(&fs_info->scrub_pause_req)) {
 			/* push queued extents */
-			atomic_set(&sctx->wr_ctx.flush_all_writes, 1);
+			atomic_set(&sctx->flush_all_writes, 1);
 			scrub_submit(sctx);
-			mutex_lock(&sctx->wr_ctx.wr_lock);
+			mutex_lock(&sctx->wr_lock);
 			scrub_wr_submit(sctx);
-			mutex_unlock(&sctx->wr_ctx.wr_lock);
+			mutex_unlock(&sctx->wr_lock);
 			wait_event(sctx->list_wait,
 				   atomic_read(&sctx->bios_in_flight) == 0);
-			atomic_set(&sctx->wr_ctx.flush_all_writes, 0);
+			atomic_set(&sctx->flush_all_writes, 0);
 			scrub_blocked_if_needed(fs_info);
 		}
 
@@ -3422,9 +3654,9 @@ skip:
 out:
 	/* push queued extents */
 	scrub_submit(sctx);
-	mutex_lock(&sctx->wr_ctx.wr_lock);
+	mutex_lock(&sctx->wr_lock);
 	scrub_wr_submit(sctx);
-	mutex_unlock(&sctx->wr_ctx.wr_lock);
+	mutex_unlock(&sctx->wr_lock);
 
 	blk_finish_plug(&plug);
 	btrfs_free_path(path);
@@ -3604,7 +3836,7 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
 			 */
 			btrfs_wait_block_group_reservations(cache);
 			btrfs_wait_nocow_writers(cache);
-			ret = btrfs_wait_ordered_roots(fs_info, -1,
+			ret = btrfs_wait_ordered_roots(fs_info, U64_MAX,
 						       cache->key.objectid,
 						       cache->key.offset);
 			if (ret > 0) {
@@ -3661,11 +3893,11 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
 		 * write requests are really completed when bios_in_flight
 		 * changes to 0.
 		 */
-		atomic_set(&sctx->wr_ctx.flush_all_writes, 1);
+		atomic_set(&sctx->flush_all_writes, 1);
 		scrub_submit(sctx);
-		mutex_lock(&sctx->wr_ctx.wr_lock);
+		mutex_lock(&sctx->wr_lock);
 		scrub_wr_submit(sctx);
-		mutex_unlock(&sctx->wr_ctx.wr_lock);
+		mutex_unlock(&sctx->wr_lock);
 
 		wait_event(sctx->list_wait,
 			   atomic_read(&sctx->bios_in_flight) == 0);
@@ -3679,7 +3911,7 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
 		 */
 		wait_event(sctx->list_wait,
 			   atomic_read(&sctx->workers_pending) == 0);
-		atomic_set(&sctx->wr_ctx.flush_all_writes, 0);
+		atomic_set(&sctx->flush_all_writes, 0);
 
 		scrub_pause_off(fs_info);
 
@@ -4082,32 +4314,6 @@ static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
 	btrfs_put_bbio(bbio);
 }
 
-static int scrub_setup_wr_ctx(struct scrub_wr_ctx *wr_ctx,
-			      struct btrfs_device *dev,
-			      int is_dev_replace)
-{
-	WARN_ON(wr_ctx->wr_curr_bio != NULL);
-
-	mutex_init(&wr_ctx->wr_lock);
-	wr_ctx->wr_curr_bio = NULL;
-	if (!is_dev_replace)
-		return 0;
-
-	WARN_ON(!dev->bdev);
-	wr_ctx->pages_per_wr_bio = SCRUB_PAGES_PER_WR_BIO;
-	wr_ctx->tgtdev = dev;
-	atomic_set(&wr_ctx->flush_all_writes, 0);
-	return 0;
-}
-
-static void scrub_free_wr_ctx(struct scrub_wr_ctx *wr_ctx)
-{
-	mutex_lock(&wr_ctx->wr_lock);
-	kfree(wr_ctx->wr_curr_bio);
-	wr_ctx->wr_curr_bio = NULL;
-	mutex_unlock(&wr_ctx->wr_lock);
-}
-
 static int copy_nocow_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
 			    int mirror_num, u64 physical_for_dev_replace)
 {
@@ -4410,7 +4616,7 @@ static int write_page_nocow(struct scrub_ctx *sctx,
 	struct btrfs_device *dev;
 	int ret;
 
-	dev = sctx->wr_ctx.tgtdev;
+	dev = sctx->wr_tgtdev;
 	if (!dev)
 		return -EIO;
 	if (!dev->bdev) {
@@ -4418,13 +4624,7 @@ static int write_page_nocow(struct scrub_ctx *sctx,
 			"scrub write_page_nocow(bdev == NULL) is unexpected");
 		return -EIO;
 	}
-	bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
-	if (!bio) {
-		spin_lock(&sctx->stat_lock);
-		sctx->stat.malloc_errors++;
-		spin_unlock(&sctx->stat_lock);
-		return -ENOMEM;
-	}
+	bio = btrfs_io_bio_alloc(1);
 	bio->bi_iter.bi_size = 0;
 	bio->bi_iter.bi_sector = physical_for_dev_replace >> 9;
 	bio->bi_bdev = dev->bdev;