[PATCH] btrfs: Use io_bio->mirror_num for all mirror_num needs

[Goldwyn Rodrigues <rgoldwyn@suse.de>]

Simplification.

btrfs_io_bio has a mirror_num field which is under-used. The mirror_num
is available when the io_bio is allocated, ie as an argument to the
function where bio is allocated. Set it when a new bio (and in
essence io_bio) is allocated. The makes passing mirror_num as function
arguments unnecessary.

The io_bio->mirror_num is also used as the failed mirror number of the
failed_bio as opposed to explicitly being passed as the function
argument.

Similarly, async_submit_bio.mirror_num is also made unnecessary because it
carries the pointer to the bio.

compressed_bio->mirror_num is also set by the bio passed (which
eventually becomes compressed_bio->orig_bio). So any io_bio allocated by
compressed_bio sequence is also assigned from cb->mirror_num.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
---
 fs/btrfs/compression.c | 14 ++++++++------
 fs/btrfs/compression.h |  2 +-
 fs/btrfs/ctree.h       |  2 +-
 fs/btrfs/disk-io.c     | 14 ++++++--------
 fs/btrfs/disk-io.h     |  4 ++--
 fs/btrfs/extent_io.c   | 28 +++++++++++++++-------------
 fs/btrfs/extent_io.h   |  6 ++----
 fs/btrfs/inode.c       | 18 ++++++++----------
 fs/btrfs/volumes.c     |  4 ++--
 fs/btrfs/volumes.h     |  3 +--
 10 files changed, 46 insertions(+), 49 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 9a023ae0f98b..576e22ab0932 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -485,7 +485,7 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
 				BUG_ON(ret); /* -ENOMEM */
 			}
 
-			ret = btrfs_map_bio(fs_info, bio, 0);
+			ret = btrfs_map_bio(fs_info, bio);
 			if (ret) {
 				bio->bi_status = ret;
 				bio_endio(bio);
@@ -521,7 +521,7 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
 		BUG_ON(ret); /* -ENOMEM */
 	}
 
-	ret = btrfs_map_bio(fs_info, bio, 0);
+	ret = btrfs_map_bio(fs_info, bio);
 	if (ret) {
 		bio->bi_status = ret;
 		bio_endio(bio);
@@ -662,7 +662,7 @@ static noinline int add_ra_bio_pages(struct inode *inode,
  * bio we were passed and then call the bio end_io calls
  */
 blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
-				 int mirror_num, unsigned long bio_flags)
+				 unsigned long bio_flags)
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	struct extent_map_tree *em_tree;
@@ -699,7 +699,7 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 	refcount_set(&cb->pending_bios, 0);
 	cb->errors = 0;
 	cb->inode = inode;
-	cb->mirror_num = mirror_num;
+	cb->mirror_num = btrfs_io_bio(bio)->mirror_num;
 	sums = cb->sums;
 
 	cb->start = em->orig_start;
@@ -741,6 +741,7 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 	comp_bio->bi_opf = REQ_OP_READ;
 	comp_bio->bi_private = cb;
 	comp_bio->bi_end_io = end_compressed_bio_read;
+	btrfs_io_bio(comp_bio)->mirror_num = cb->mirror_num;
 	refcount_set(&cb->pending_bios, 1);
 
 	for (pg_index = 0; pg_index < nr_pages; pg_index++) {
@@ -789,7 +790,7 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 						  fs_info->sectorsize);
 			sums += fs_info->csum_size * nr_sectors;
 
-			ret = btrfs_map_bio(fs_info, comp_bio, mirror_num);
+			ret = btrfs_map_bio(fs_info, comp_bio);
 			if (ret) {
 				comp_bio->bi_status = ret;
 				bio_endio(comp_bio);
@@ -799,6 +800,7 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 			comp_bio->bi_opf = REQ_OP_READ;
 			comp_bio->bi_private = cb;
 			comp_bio->bi_end_io = end_compressed_bio_read;
+			btrfs_io_bio(comp_bio)->mirror_num = cb->mirror_num;
 
 			bio_add_page(comp_bio, page, pg_len, 0);
 		}
@@ -811,7 +813,7 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 	ret = btrfs_lookup_bio_sums(inode, comp_bio, sums);
 	BUG_ON(ret); /* -ENOMEM */
 
-	ret = btrfs_map_bio(fs_info, comp_bio, mirror_num);
+	ret = btrfs_map_bio(fs_info, comp_bio);
 	if (ret) {
 		comp_bio->bi_status = ret;
 		bio_endio(comp_bio);
diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index c359f20920d0..1476d58d2dc3 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -98,7 +98,7 @@ blk_status_t btrfs_submit_compressed_write(struct btrfs_inode *inode, u64 start,
 				  unsigned int write_flags,
 				  struct cgroup_subsys_state *blkcg_css);
 blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
-				 int mirror_num, unsigned long bio_flags);
+				 unsigned long bio_flags);
 
 unsigned int btrfs_compress_str2level(unsigned int type, const char *str);
 
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 4a69aa604ac5..087c6b3edb61 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3107,7 +3107,7 @@ u64 btrfs_file_extent_end(const struct btrfs_path *path);
 
 /* inode.c */
 blk_status_t btrfs_submit_data_bio(struct inode *inode, struct bio *bio,
-				   int mirror_num, unsigned long bio_flags);
+				   unsigned long bio_flags);
 unsigned int btrfs_verify_data_csum(struct btrfs_io_bio *io_bio, u32 bio_offset,
 				    struct page *page, u64 start, u64 end);
 struct extent_map *btrfs_get_extent_fiemap(struct btrfs_inode *inode,
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index b117dd3b8172..fdf95c832099 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -113,7 +113,6 @@ struct async_submit_bio {
 	struct inode *inode;
 	struct bio *bio;
 	extent_submit_bio_start_t *submit_bio_start;
-	int mirror_num;
 
 	/* Optional parameter for submit_bio_start used by direct io */
 	u64 dio_file_offset;
@@ -827,7 +826,7 @@ static void run_one_async_done(struct btrfs_work *work)
 	 * This changes nothing when cgroups aren't in use.
 	 */
 	async->bio->bi_opf |= REQ_CGROUP_PUNT;
-	ret = btrfs_map_bio(btrfs_sb(inode->i_sb), async->bio, async->mirror_num);
+	ret = btrfs_map_bio(btrfs_sb(inode->i_sb), async->bio);
 	if (ret) {
 		async->bio->bi_status = ret;
 		bio_endio(async->bio);
@@ -843,7 +842,7 @@ static void run_one_async_free(struct btrfs_work *work)
 }
 
 blk_status_t btrfs_wq_submit_bio(struct inode *inode, struct bio *bio,
-				 int mirror_num, unsigned long bio_flags,
+				 unsigned long bio_flags,
 				 u64 dio_file_offset,
 				 extent_submit_bio_start_t *submit_bio_start)
 {
@@ -856,7 +855,6 @@ blk_status_t btrfs_wq_submit_bio(struct inode *inode, struct bio *bio,
 
 	async->inode = inode;
 	async->bio = bio;
-	async->mirror_num = mirror_num;
 	async->submit_bio_start = submit_bio_start;
 
 	btrfs_init_work(&async->work, run_one_async_start, run_one_async_done,
@@ -914,7 +912,7 @@ static bool should_async_write(struct btrfs_fs_info *fs_info,
 }
 
 blk_status_t btrfs_submit_metadata_bio(struct inode *inode, struct bio *bio,
-				       int mirror_num, unsigned long bio_flags)
+				       unsigned long bio_flags)
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	blk_status_t ret;
@@ -928,18 +926,18 @@ blk_status_t btrfs_submit_metadata_bio(struct inode *inode, struct bio *bio,
 					  BTRFS_WQ_ENDIO_METADATA);
 		if (ret)
 			goto out_w_error;
-		ret = btrfs_map_bio(fs_info, bio, mirror_num);
+		ret = btrfs_map_bio(fs_info, bio);
 	} else if (!should_async_write(fs_info, BTRFS_I(inode))) {
 		ret = btree_csum_one_bio(bio);
 		if (ret)
 			goto out_w_error;
-		ret = btrfs_map_bio(fs_info, bio, mirror_num);
+		ret = btrfs_map_bio(fs_info, bio);
 	} else {
 		/*
 		 * kthread helpers are used to submit writes so that
 		 * checksumming can happen in parallel across all CPUs
 		 */
-		ret = btrfs_wq_submit_bio(inode, bio, mirror_num, 0,
+		ret = btrfs_wq_submit_bio(inode, bio, 0,
 					  0, btree_submit_bio_start);
 	}
 
diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index 0e7e9526b6a8..7ca535655f47 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -85,7 +85,7 @@ int btrfs_validate_metadata_buffer(struct btrfs_io_bio *io_bio,
 				   struct page *page, u64 start, u64 end,
 				   int mirror);
 blk_status_t btrfs_submit_metadata_bio(struct inode *inode, struct bio *bio,
-				       int mirror_num, unsigned long bio_flags);
+				       unsigned long bio_flags);
 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
 struct btrfs_root *btrfs_alloc_dummy_root(struct btrfs_fs_info *fs_info);
 #endif
@@ -115,7 +115,7 @@ int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid, int level,
 blk_status_t btrfs_bio_wq_end_io(struct btrfs_fs_info *info, struct bio *bio,
 			enum btrfs_wq_endio_type metadata);
 blk_status_t btrfs_wq_submit_bio(struct inode *inode, struct bio *bio,
-				 int mirror_num, unsigned long bio_flags,
+				 unsigned long bio_flags,
 				 u64 dio_file_offset,
 				 extent_submit_bio_start_t *submit_bio_start);
 blk_status_t btrfs_submit_bio_done(void *private_data, struct bio *bio,
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 54f96767cddc..e5bc1eeb0c44 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -164,8 +164,7 @@ static int add_extent_changeset(struct extent_state *state, u32 bits,
 	return ret;
 }
 
-int __must_check submit_one_bio(struct bio *bio, int mirror_num,
-				unsigned long bio_flags)
+int __must_check submit_one_bio(struct bio *bio, unsigned long bio_flags)
 {
 	blk_status_t ret = 0;
 	struct extent_io_tree *tree = bio->bi_private;
@@ -173,11 +172,11 @@ int __must_check submit_one_bio(struct bio *bio, int mirror_num,
 	bio->bi_private = NULL;
 
 	if (is_data_inode(tree->private_data))
-		ret = btrfs_submit_data_bio(tree->private_data, bio, mirror_num,
+		ret = btrfs_submit_data_bio(tree->private_data, bio,
 					    bio_flags);
 	else
 		ret = btrfs_submit_metadata_bio(tree->private_data, bio,
-						mirror_num, bio_flags);
+						bio_flags);
 
 	return blk_status_to_errno(ret);
 }
@@ -206,7 +205,7 @@ static int __must_check flush_write_bio(struct extent_page_data *epd)
 	struct bio *bio = epd->bio_ctrl.bio;
 
 	if (bio) {
-		ret = submit_one_bio(bio, 0, 0);
+		ret = submit_one_bio(bio, 0);
 		/*
 		 * Clean up of epd->bio is handled by its endio function.
 		 * And endio is either triggered by successful bio execution
@@ -2620,7 +2619,7 @@ static bool btrfs_check_repairable(struct inode *inode,
 int btrfs_repair_one_sector(struct inode *inode,
 			    struct bio *failed_bio, u32 bio_offset,
 			    struct page *page, unsigned int pgoff,
-			    u64 start, int failed_mirror,
+			    u64 start,
 			    submit_bio_hook_t *submit_bio_hook)
 {
 	struct io_failure_record *failrec;
@@ -2628,6 +2627,7 @@ int btrfs_repair_one_sector(struct inode *inode,
 	struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
 	struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
 	struct btrfs_io_bio *failed_io_bio = btrfs_io_bio(failed_bio);
+	int failed_mirror = failed_io_bio->mirror_num;
 	const int icsum = bio_offset >> fs_info->sectorsize_bits;
 	struct bio *repair_bio;
 	struct btrfs_io_bio *repair_io_bio;
@@ -2654,6 +2654,7 @@ int btrfs_repair_one_sector(struct inode *inode,
 	repair_bio->bi_end_io = failed_bio->bi_end_io;
 	repair_bio->bi_iter.bi_sector = failrec->logical >> 9;
 	repair_bio->bi_private = failed_bio->bi_private;
+	btrfs_io_bio(repair_bio)->mirror_num = failrec->this_mirror;
 
 	if (failed_io_bio->csum) {
 		const u32 csum_size = fs_info->csum_size;
@@ -2671,8 +2672,7 @@ int btrfs_repair_one_sector(struct inode *inode,
 		    "repair read error: submitting new read to mirror %d",
 		    failrec->this_mirror);
 
-	status = submit_bio_hook(inode, repair_bio, failrec->this_mirror,
-				 failrec->bio_flags);
+	status = submit_bio_hook(inode, repair_bio, failrec->bio_flags);
 	if (status) {
 		free_io_failure(failure_tree, tree, failrec);
 		bio_put(repair_bio);
@@ -2743,7 +2743,7 @@ static blk_status_t submit_read_repair(struct inode *inode,
 		ret = btrfs_repair_one_sector(inode, failed_bio,
 				bio_offset + offset,
 				page, pgoff + offset, start + offset,
-				failed_mirror, submit_bio_hook);
+				submit_bio_hook);
 		if (!ret) {
 			/*
 			 * We have submitted the read repair, the page release
@@ -3139,6 +3139,7 @@ struct bio *btrfs_bio_clone(struct bio *bio)
 	btrfs_bio = btrfs_io_bio(new);
 	btrfs_io_bio_init(btrfs_bio);
 	btrfs_bio->iter = bio->bi_iter;
+	btrfs_bio->mirror_num = btrfs_io_bio(bio)->mirror_num;
 	return new;
 }
 
@@ -3318,7 +3319,7 @@ static int submit_extent_page(unsigned int opf,
 		if (force_bio_submit ||
 		    !btrfs_bio_add_page(bio_ctrl, page, disk_bytenr, io_size,
 					pg_offset, bio_flags)) {
-			ret = submit_one_bio(bio, mirror_num, bio_ctrl->bio_flags);
+			ret = submit_one_bio(bio, bio_ctrl->bio_flags);
 			bio_ctrl->bio = NULL;
 			if (ret < 0)
 				return ret;
@@ -3335,6 +3336,7 @@ static int submit_extent_page(unsigned int opf,
 	bio->bi_private = tree;
 	bio->bi_write_hint = page->mapping->host->i_write_hint;
 	bio->bi_opf = opf;
+	btrfs_io_bio(bio)->mirror_num = mirror_num;
 	if (wbc) {
 		struct block_device *bdev;
 
@@ -5039,7 +5041,7 @@ void extent_readahead(struct readahead_control *rac)
 		free_extent_map(em_cached);
 
 	if (bio_ctrl.bio) {
-		if (submit_one_bio(bio_ctrl.bio, 0, bio_ctrl.bio_flags))
+		if (submit_one_bio(bio_ctrl.bio, bio_ctrl.bio_flags))
 			return;
 	}
 }
@@ -6383,7 +6385,7 @@ static int read_extent_buffer_subpage(struct extent_buffer *eb, int wait,
 	if (bio_ctrl.bio) {
 		int tmp;
 
-		tmp = submit_one_bio(bio_ctrl.bio, mirror_num, 0);
+		tmp = submit_one_bio(bio_ctrl.bio, 0);
 		bio_ctrl.bio = NULL;
 		if (tmp < 0)
 			return tmp;
@@ -6491,7 +6493,7 @@ int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num)
 	}
 
 	if (bio_ctrl.bio) {
-		err = submit_one_bio(bio_ctrl.bio, mirror_num, bio_ctrl.bio_flags);
+		err = submit_one_bio(bio_ctrl.bio, bio_ctrl.bio_flags);
 		bio_ctrl.bio = NULL;
 		if (err)
 			return err;
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 62027f551b44..8568f5bfe089 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -71,7 +71,6 @@ struct io_failure_record;
 struct extent_io_tree;
 
 typedef blk_status_t (submit_bio_hook_t)(struct inode *inode, struct bio *bio,
-					 int mirror_num,
 					 unsigned long bio_flags);
 
 typedef blk_status_t (extent_submit_bio_start_t)(struct inode *inode,
@@ -177,8 +176,7 @@ typedef struct extent_map *(get_extent_t)(struct btrfs_inode *inode,
 int try_release_extent_mapping(struct page *page, gfp_t mask);
 int try_release_extent_buffer(struct page *page);
 
-int __must_check submit_one_bio(struct bio *bio, int mirror_num,
-				unsigned long bio_flags);
+int __must_check submit_one_bio(struct bio *bio, unsigned long bio_flags);
 int btrfs_do_readpage(struct page *page, struct extent_map **em_cached,
 		      struct btrfs_bio_ctrl *bio_ctrl,
 		      unsigned int read_flags, u64 *prev_em_start);
@@ -309,7 +307,7 @@ struct io_failure_record {
 int btrfs_repair_one_sector(struct inode *inode,
 			    struct bio *failed_bio, u32 bio_offset,
 			    struct page *page, unsigned int pgoff,
-			    u64 start, int failed_mirror,
+			    u64 start,
 			    submit_bio_hook_t *submit_bio_hook);
 
 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 8f60314c36c5..ad4308546006 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2465,7 +2465,7 @@ static blk_status_t extract_ordered_extent(struct btrfs_inode *inode,
  *    c-3) otherwise:			async submit
  */
 blk_status_t btrfs_submit_data_bio(struct inode *inode, struct bio *bio,
-				   int mirror_num, unsigned long bio_flags)
+				   unsigned long bio_flags)
 
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
@@ -2497,7 +2497,6 @@ blk_status_t btrfs_submit_data_bio(struct inode *inode, struct bio *bio,
 
 		if (bio_flags & EXTENT_BIO_COMPRESSED) {
 			ret = btrfs_submit_compressed_read(inode, bio,
-							   mirror_num,
 							   bio_flags);
 			goto out;
 		} else {
@@ -2516,7 +2515,7 @@ blk_status_t btrfs_submit_data_bio(struct inode *inode, struct bio *bio,
 		if (root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID)
 			goto mapit;
 		/* we're doing a write, do the async checksumming */
-		ret = btrfs_wq_submit_bio(inode, bio, mirror_num, bio_flags,
+		ret = btrfs_wq_submit_bio(inode, bio, bio_flags,
 					  0, btrfs_submit_bio_start);
 		goto out;
 	} else if (!skip_sum) {
@@ -2526,7 +2525,7 @@ blk_status_t btrfs_submit_data_bio(struct inode *inode, struct bio *bio,
 	}
 
 mapit:
-	ret = btrfs_map_bio(fs_info, bio, mirror_num);
+	ret = btrfs_map_bio(fs_info, bio);
 
 out:
 	if (ret) {
@@ -7999,7 +7998,6 @@ static void btrfs_dio_private_put(struct btrfs_dio_private *dip)
 }
 
 static blk_status_t submit_dio_repair_bio(struct inode *inode, struct bio *bio,
-					  int mirror_num,
 					  unsigned long bio_flags)
 {
 	struct btrfs_dio_private *dip = bio->bi_private;
@@ -8013,7 +8011,7 @@ static blk_status_t submit_dio_repair_bio(struct inode *inode, struct bio *bio,
 		return ret;
 
 	refcount_inc(&dip->refs);
-	ret = btrfs_map_bio(fs_info, bio, mirror_num);
+	ret = btrfs_map_bio(fs_info, bio);
 	if (ret)
 		refcount_dec(&dip->refs);
 	return ret;
@@ -8057,7 +8055,7 @@ static blk_status_t btrfs_check_read_dio_bio(struct inode *inode,
 						&io_bio->bio,
 						start - io_bio->logical,
 						bvec.bv_page, pgoff,
-						start, io_bio->mirror_num,
+						start,
 						submit_dio_repair_bio);
 				if (ret)
 					err = errno_to_blk_status(ret);
@@ -8134,7 +8132,7 @@ static inline blk_status_t btrfs_submit_dio_bio(struct bio *bio,
 		goto map;
 
 	if (write && async_submit) {
-		ret = btrfs_wq_submit_bio(inode, bio, 0, 0, file_offset,
+		ret = btrfs_wq_submit_bio(inode, bio, 0, file_offset,
 					  btrfs_submit_bio_start_direct_io);
 		goto err;
 	} else if (write) {
@@ -8154,7 +8152,7 @@ static inline blk_status_t btrfs_submit_dio_bio(struct bio *bio,
 		btrfs_io_bio(bio)->csum = dip->csums + csum_offset;
 	}
 map:
-	ret = btrfs_map_bio(fs_info, bio, 0);
+	ret = btrfs_map_bio(fs_info, bio);
 err:
 	return ret;
 }
@@ -8361,7 +8359,7 @@ int btrfs_readpage(struct file *file, struct page *page)
 
 	ret = btrfs_do_readpage(page, NULL, &bio_ctrl, 0, NULL);
 	if (bio_ctrl.bio)
-		ret = submit_one_bio(bio_ctrl.bio, 0, bio_ctrl.bio_flags);
+		ret = submit_one_bio(bio_ctrl.bio, bio_ctrl.bio_flags);
 	return ret;
 }
 
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index c6c14315b1c9..9485e71dce0d 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6758,8 +6758,7 @@ static void bbio_error(struct btrfs_bio *bbio, struct bio *bio, u64 logical)
 	}
 }
 
-blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio,
-			   int mirror_num)
+blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio)
 {
 	struct btrfs_device *dev;
 	struct bio *first_bio = bio;
@@ -6770,6 +6769,7 @@ blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio,
 	int dev_nr;
 	int total_devs;
 	struct btrfs_bio *bbio = NULL;
+	int mirror_num = btrfs_io_bio(bio)->mirror_num;
 
 	length = bio->bi_iter.bi_size;
 	map_length = length;
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 55a8ba244716..776f45f4299b 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -453,8 +453,7 @@ int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info);
 struct btrfs_block_group *btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 					    u64 type);
 void btrfs_mapping_tree_free(struct extent_map_tree *tree);
-blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio,
-			   int mirror_num);
+blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio);
 int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
 		       fmode_t flags, void *holder);
 struct btrfs_device *btrfs_scan_one_device(const char *path,
-- 
2.32.0


-- 
Goldwyn