diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
index 6dac3a7e239b..573bb7514fce 100644
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@ -4,4 +4,4 @@
 
 obj-y := btrfs.o chunk-map.o compression.o ctree.o dev.o dir-item.o \
 	extent-io.o inode.o root.o subvolume.o crypto/hash.o disk-io.o \
-	common/rbtree-utils.o extent-cache.o extent-io.o
+	common/rbtree-utils.o extent-cache.o extent-io.o volumes.o
diff --git a/fs/btrfs/compat.h b/fs/btrfs/compat.h
index 64e8b8ab3dfb..8840e509f32c 100644
--- a/fs/btrfs/compat.h
+++ b/fs/btrfs/compat.h
@@ -67,4 +67,9 @@ static inline void uuid_unparse(const u8 *uuid, char *out)
 	return uuid_bin_to_str((unsigned char *)uuid, out, 0);
 }
 
+static inline int is_power_of_2(unsigned long n)
+{
+	return (n != 0 && ((n & (n - 1)) == 0));
+}
+
 #endif
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
new file mode 100644
index 000000000000..63853cb2a1dd
--- /dev/null
+++ b/fs/btrfs/volumes.c
@@ -0,0 +1,872 @@
+// SPDX-License-Identifier: GPL-2.0+
+#include <stdlib.h>
+#include <common.h>
+#include <fs_internal.h>
+#include "ctree.h"
+#include "disk-io.h"
+#include "volumes.h"
+
+const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = {
+	[BTRFS_RAID_RAID10] = {
+		.sub_stripes	= 2,
+		.dev_stripes	= 1,
+		.devs_max	= 0,	/* 0 == as many as possible */
+		.devs_min	= 4,
+		.tolerated_failures = 1,
+		.devs_increment	= 2,
+		.ncopies	= 2,
+		.nparity        = 0,
+		.raid_name	= "raid10",
+		.bg_flag	= BTRFS_BLOCK_GROUP_RAID10,
+	},
+	[BTRFS_RAID_RAID1] = {
+		.sub_stripes	= 1,
+		.dev_stripes	= 1,
+		.devs_max	= 2,
+		.devs_min	= 2,
+		.tolerated_failures = 1,
+		.devs_increment	= 2,
+		.ncopies	= 2,
+		.nparity        = 0,
+		.raid_name	= "raid1",
+		.bg_flag	= BTRFS_BLOCK_GROUP_RAID1,
+	},
+	[BTRFS_RAID_RAID1C3] = {
+		.sub_stripes	= 1,
+		.dev_stripes	= 1,
+		.devs_max	= 3,
+		.devs_min	= 3,
+		.tolerated_failures = 2,
+		.devs_increment	= 3,
+		.ncopies	= 3,
+		.raid_name	= "raid1c3",
+		.bg_flag	= BTRFS_BLOCK_GROUP_RAID1C3,
+	},
+	[BTRFS_RAID_RAID1C4] = {
+		.sub_stripes	= 1,
+		.dev_stripes	= 1,
+		.devs_max	= 4,
+		.devs_min	= 4,
+		.tolerated_failures = 3,
+		.devs_increment	= 4,
+		.ncopies	= 4,
+		.raid_name	= "raid1c4",
+		.bg_flag	= BTRFS_BLOCK_GROUP_RAID1C4,
+	},
+	[BTRFS_RAID_DUP] = {
+		.sub_stripes	= 1,
+		.dev_stripes	= 2,
+		.devs_max	= 1,
+		.devs_min	= 1,
+		.tolerated_failures = 0,
+		.devs_increment	= 1,
+		.ncopies	= 2,
+		.nparity        = 0,
+		.raid_name	= "dup",
+		.bg_flag	= BTRFS_BLOCK_GROUP_DUP,
+	},
+	[BTRFS_RAID_RAID0] = {
+		.sub_stripes	= 1,
+		.dev_stripes	= 1,
+		.devs_max	= 0,
+		.devs_min	= 2,
+		.tolerated_failures = 0,
+		.devs_increment	= 1,
+		.ncopies	= 1,
+		.nparity        = 0,
+		.raid_name	= "raid0",
+		.bg_flag	= BTRFS_BLOCK_GROUP_RAID0,
+	},
+	[BTRFS_RAID_SINGLE] = {
+		.sub_stripes	= 1,
+		.dev_stripes	= 1,
+		.devs_max	= 1,
+		.devs_min	= 1,
+		.tolerated_failures = 0,
+		.devs_increment	= 1,
+		.ncopies	= 1,
+		.nparity        = 0,
+		.raid_name	= "single",
+		.bg_flag	= 0,
+	},
+	[BTRFS_RAID_RAID5] = {
+		.sub_stripes	= 1,
+		.dev_stripes	= 1,
+		.devs_max	= 0,
+		.devs_min	= 2,
+		.tolerated_failures = 1,
+		.devs_increment	= 1,
+		.ncopies	= 1,
+		.nparity        = 1,
+		.raid_name	= "raid5",
+		.bg_flag	= BTRFS_BLOCK_GROUP_RAID5,
+	},
+	[BTRFS_RAID_RAID6] = {
+		.sub_stripes	= 1,
+		.dev_stripes	= 1,
+		.devs_max	= 0,
+		.devs_min	= 3,
+		.tolerated_failures = 2,
+		.devs_increment	= 1,
+		.ncopies	= 1,
+		.nparity        = 2,
+		.raid_name	= "raid6",
+		.bg_flag	= BTRFS_BLOCK_GROUP_RAID6,
+	},
+};
+
+struct stripe {
+	struct btrfs_device *dev;
+	u64 physical;
+};
+
+static inline int nr_parity_stripes(struct map_lookup *map)
+{
+	if (map->type & BTRFS_BLOCK_GROUP_RAID5)
+		return 1;
+	else if (map->type & BTRFS_BLOCK_GROUP_RAID6)
+		return 2;
+	else
+		return 0;
+}
+
+static inline int nr_data_stripes(struct map_lookup *map)
+{
+	return map->num_stripes - nr_parity_stripes(map);
+}
+
+#define is_parity_stripe(x) ( ((x) == BTRFS_RAID5_P_STRIPE) || ((x) == BTRFS_RAID6_Q_STRIPE) )
+
+static LIST_HEAD(fs_uuids);
+
+/*
+ * Find a device specified by @devid or @uuid in the list of @fs_devices, or
+ * return NULL.
+ *
+ * If devid and uuid are both specified, the match must be exact, otherwise
+ * only devid is used.
+ */
+static struct btrfs_device *find_device(struct btrfs_fs_devices *fs_devices,
+		u64 devid, u8 *uuid)
+{
+	struct list_head *head = &fs_devices->devices;
+	struct btrfs_device *dev;
+
+	list_for_each_entry(dev, head, dev_list) {
+		if (dev->devid == devid &&
+		    (!uuid || !memcmp(dev->uuid, uuid, BTRFS_UUID_SIZE))) {
+			return dev;
+		}
+	}
+	return NULL;
+}
+
+static struct btrfs_fs_devices *find_fsid(u8 *fsid, u8 *metadata_uuid)
+{
+	struct btrfs_fs_devices *fs_devices;
+
+	list_for_each_entry(fs_devices, &fs_uuids, list) {
+		if (metadata_uuid && (memcmp(fsid, fs_devices->fsid,
+					     BTRFS_FSID_SIZE) == 0) &&
+		    (memcmp(metadata_uuid, fs_devices->metadata_uuid,
+			    BTRFS_FSID_SIZE) == 0)) {
+			return fs_devices;
+		} else if (memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE) == 0){
+			return fs_devices;
+		}
+	}
+	return NULL;
+}
+
+static int device_list_add(struct btrfs_super_block *disk_super,
+			   u64 devid, struct blk_desc *desc,
+			   disk_partition_t *part,
+			   struct btrfs_fs_devices **fs_devices_ret)
+{
+	struct btrfs_device *device;
+	struct btrfs_fs_devices *fs_devices;
+	u64 found_transid = btrfs_super_generation(disk_super);
+	bool metadata_uuid = (btrfs_super_incompat_flags(disk_super) &
+		BTRFS_FEATURE_INCOMPAT_METADATA_UUID);
+
+	if (metadata_uuid)
+		fs_devices = find_fsid(disk_super->fsid,
+				       disk_super->metadata_uuid);
+	else
+		fs_devices = find_fsid(disk_super->fsid, NULL);
+
+	if (!fs_devices) {
+		fs_devices = kzalloc(sizeof(*fs_devices), GFP_NOFS);
+		if (!fs_devices)
+			return -ENOMEM;
+		INIT_LIST_HEAD(&fs_devices->devices);
+		list_add(&fs_devices->list, &fs_uuids);
+		memcpy(fs_devices->fsid, disk_super->fsid, BTRFS_FSID_SIZE);
+		if (metadata_uuid)
+			memcpy(fs_devices->metadata_uuid,
+			       disk_super->metadata_uuid, BTRFS_FSID_SIZE);
+		else
+			memcpy(fs_devices->metadata_uuid, fs_devices->fsid,
+			       BTRFS_FSID_SIZE);
+
+		fs_devices->latest_devid = devid;
+		fs_devices->latest_trans = found_transid;
+		fs_devices->lowest_devid = (u64)-1;
+		device = NULL;
+	} else {
+		device = find_device(fs_devices, devid,
+				       disk_super->dev_item.uuid);
+	}
+	if (!device) {
+		device = kzalloc(sizeof(*device), GFP_NOFS);
+		if (!device) {
+			/* we can safely leave the fs_devices entry around */
+			return -ENOMEM;
+		}
+		device->devid = devid;
+		device->desc = desc;
+		device->part = part;
+		device->generation = found_transid;
+		memcpy(device->uuid, disk_super->dev_item.uuid,
+		       BTRFS_UUID_SIZE);
+		device->total_devs = btrfs_super_num_devices(disk_super);
+		device->super_bytes_used = btrfs_super_bytes_used(disk_super);
+		device->total_bytes =
+			btrfs_stack_device_total_bytes(&disk_super->dev_item);
+		device->bytes_used =
+			btrfs_stack_device_bytes_used(&disk_super->dev_item);
+		list_add(&device->dev_list, &fs_devices->devices);
+		device->fs_devices = fs_devices;
+	} else if (!device->desc || !device->part) {
+		/*
+		 * The existing device has newer generation, so this one could
+		 * be a stale one, don't add it.
+		 */
+		if (found_transid < device->generation) {
+			error(
+	"adding devid %llu gen %llu but found an existing device gen %llu",
+				device->devid, found_transid,
+				device->generation);
+			return -EEXIST;
+		} else {
+			device->desc = desc;
+			device->part = part;
+		}
+        }
+
+
+	if (found_transid > fs_devices->latest_trans) {
+		fs_devices->latest_devid = devid;
+		fs_devices->latest_trans = found_transid;
+	}
+	if (fs_devices->lowest_devid > devid) {
+		fs_devices->lowest_devid = devid;
+	}
+	*fs_devices_ret = fs_devices;
+	return 0;
+}
+
+int btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
+{
+	struct btrfs_fs_devices *seed_devices;
+	struct btrfs_device *device;
+	int ret = 0;
+
+again:
+	if (!fs_devices)
+		return 0;
+	while (!list_empty(&fs_devices->devices)) {
+		device = list_entry(fs_devices->devices.next,
+				    struct btrfs_device, dev_list);
+		list_del(&device->dev_list);
+		/* free the memory */
+		free(device);
+	}
+
+	seed_devices = fs_devices->seed;
+	fs_devices->seed = NULL;
+	if (seed_devices) {
+		struct btrfs_fs_devices *orig;
+
+		orig = fs_devices;
+		fs_devices = seed_devices;
+		list_del(&orig->list);
+		free(orig);
+		goto again;
+	} else {
+		list_del(&fs_devices->list);
+		free(fs_devices);
+	}
+
+	return ret;
+}
+
+void btrfs_close_all_devices(void)
+{
+	struct btrfs_fs_devices *fs_devices;
+
+	while (!list_empty(&fs_uuids)) {
+		fs_devices = list_entry(fs_uuids.next, struct btrfs_fs_devices,
+					list);
+		btrfs_close_devices(fs_devices);
+	}
+}
+
+int btrfs_open_devices(struct btrfs_fs_devices *fs_devices)
+{
+	struct btrfs_device *device;
+
+	list_for_each_entry(device, &fs_devices->devices, dev_list) {
+		if (!device->desc || !device->part) {
+			printf("no device found for devid %llu, skip it \n",
+				device->devid);
+			continue;
+		}
+	}
+	return 0;
+}
+
+int btrfs_scan_one_device(struct blk_desc *desc, disk_partition_t *part,
+			  struct btrfs_fs_devices **fs_devices_ret,
+			  u64 *total_devs)
+{
+	struct btrfs_super_block *disk_super;
+	char buf[BTRFS_SUPER_INFO_SIZE];
+	int ret;
+	u64 devid;
+
+	disk_super = (struct btrfs_super_block *)buf;
+	ret = btrfs_read_dev_super(desc, part, disk_super);
+	if (ret < 0)
+		return -EIO;
+	devid = btrfs_stack_device_id(&disk_super->dev_item);
+	if (btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_METADUMP)
+		*total_devs = 1;
+	else
+		*total_devs = btrfs_super_num_devices(disk_super);
+
+	ret = device_list_add(disk_super, devid, desc, part, fs_devices_ret);
+
+	return ret;
+}
+
+struct btrfs_device *btrfs_find_device(struct btrfs_fs_info *fs_info, u64 devid,
+				       u8 *uuid, u8 *fsid)
+{
+	struct btrfs_device *device;
+	struct btrfs_fs_devices *cur_devices;
+
+	cur_devices = fs_info->fs_devices;
+	while (cur_devices) {
+		if (!fsid ||
+		   !memcmp(cur_devices->metadata_uuid, fsid, BTRFS_FSID_SIZE)) {
+			device = find_device(cur_devices, devid, uuid);
+			if (device)
+				return device;
+		}
+		cur_devices = cur_devices->seed;
+	}
+	return NULL;
+}
+
+/*
+ * slot == -1: SYSTEM chunk
+ * return -EIO on error, otherwise return 0
+ */
+int btrfs_check_chunk_valid(struct btrfs_fs_info *fs_info,
+			    struct extent_buffer *leaf,
+			    struct btrfs_chunk *chunk,
+			    int slot, u64 logical)
+{
+	u64 length;
+	u64 stripe_len;
+	u16 num_stripes;
+	u16 sub_stripes;
+	u64 type;
+	u32 chunk_ondisk_size;
+	u32 sectorsize = fs_info->sectorsize;
+
+	/*
+	 * Basic chunk item size check.  Note that btrfs_chunk already contains
+	 * one stripe, so no "==" check.
+	 */
+	if (slot >= 0 &&
+	    btrfs_item_size_nr(leaf, slot) < sizeof(struct btrfs_chunk)) {
+		error("invalid chunk item size, have %u expect [%zu, %lu)",
+			btrfs_item_size_nr(leaf, slot),
+			sizeof(struct btrfs_chunk),
+			BTRFS_LEAF_DATA_SIZE(fs_info));
+		return -EUCLEAN;
+	}
+	length = btrfs_chunk_length(leaf, chunk);
+	stripe_len = btrfs_chunk_stripe_len(leaf, chunk);
+	num_stripes = btrfs_chunk_num_stripes(leaf, chunk);
+	sub_stripes = btrfs_chunk_sub_stripes(leaf, chunk);
+	type = btrfs_chunk_type(leaf, chunk);
+
+	if (num_stripes == 0) {
+		error("invalid num_stripes, have %u expect non-zero",
+			num_stripes);
+		return -EUCLEAN;
+	}
+	if (slot >= 0 && btrfs_chunk_item_size(num_stripes) !=
+	    btrfs_item_size_nr(leaf, slot)) {
+		error("invalid chunk item size, have %u expect %lu",
+			btrfs_item_size_nr(leaf, slot),
+			btrfs_chunk_item_size(num_stripes));
+		return -EUCLEAN;
+	}
+
+	/*
+	 * These valid checks may be insufficient to cover every corner cases.
+	 */
+	if (!IS_ALIGNED(logical, sectorsize)) {
+		error("invalid chunk logical %llu",  logical);
+		return -EIO;
+	}
+	if (btrfs_chunk_sector_size(leaf, chunk) != sectorsize) {
+		error("invalid chunk sectorsize %llu",
+		      (unsigned long long)btrfs_chunk_sector_size(leaf, chunk));
+		return -EIO;
+	}
+	if (!length || !IS_ALIGNED(length, sectorsize)) {
+		error("invalid chunk length %llu",  length);
+		return -EIO;
+	}
+	if (stripe_len != BTRFS_STRIPE_LEN) {
+		error("invalid chunk stripe length: %llu", stripe_len);
+		return -EIO;
+	}
+	/* Check on chunk item type */
+	if (slot == -1 && (type & BTRFS_BLOCK_GROUP_SYSTEM) == 0) {
+		error("invalid chunk type %llu", type);
+		return -EIO;
+	}
+	if (type & ~(BTRFS_BLOCK_GROUP_TYPE_MASK |
+		     BTRFS_BLOCK_GROUP_PROFILE_MASK)) {
+		error("unrecognized chunk type: %llu",
+		      ~(BTRFS_BLOCK_GROUP_TYPE_MASK |
+			BTRFS_BLOCK_GROUP_PROFILE_MASK) & type);
+		return -EIO;
+	}
+	if (!(type & BTRFS_BLOCK_GROUP_TYPE_MASK)) {
+		error("missing chunk type flag: %llu", type);
+		return -EIO;
+	}
+	if (!(is_power_of_2(type & BTRFS_BLOCK_GROUP_PROFILE_MASK) ||
+	      (type & BTRFS_BLOCK_GROUP_PROFILE_MASK) == 0)) {
+		error("conflicting chunk type detected: %llu", type);
+		return -EIO;
+	}
+	if ((type & BTRFS_BLOCK_GROUP_PROFILE_MASK) &&
+	    !is_power_of_2(type & BTRFS_BLOCK_GROUP_PROFILE_MASK)) {
+		error("conflicting chunk profile detected: %llu", type);
+		return -EIO;
+	}
+
+	chunk_ondisk_size = btrfs_chunk_item_size(num_stripes);
+	/*
+	 * Btrfs_chunk contains at least one stripe, and for sys_chunk
+	 * it can't exceed the system chunk array size
+	 * For normal chunk, it should match its chunk item size.
+	 */
+	if (num_stripes < 1 ||
+	    (slot == -1 && chunk_ondisk_size > BTRFS_SYSTEM_CHUNK_ARRAY_SIZE) ||
+	    (slot >= 0 && chunk_ondisk_size > btrfs_item_size_nr(leaf, slot))) {
+		error("invalid num_stripes: %u", num_stripes);
+		return -EIO;
+	}
+	/*
+	 * Device number check against profile
+	 */
+	if ((type & BTRFS_BLOCK_GROUP_RAID10 && (sub_stripes != 2 ||
+		  !IS_ALIGNED(num_stripes, sub_stripes))) ||
+	    (type & BTRFS_BLOCK_GROUP_RAID1 && num_stripes < 1) ||
+	    (type & BTRFS_BLOCK_GROUP_RAID1C3 && num_stripes < 3) ||
+	    (type & BTRFS_BLOCK_GROUP_RAID1C4 && num_stripes < 4) ||
+	    (type & BTRFS_BLOCK_GROUP_RAID5 && num_stripes < 2) ||
+	    (type & BTRFS_BLOCK_GROUP_RAID6 && num_stripes < 3) ||
+	    (type & BTRFS_BLOCK_GROUP_DUP && num_stripes > 2) ||
+	    ((type & BTRFS_BLOCK_GROUP_PROFILE_MASK) == 0 &&
+	     num_stripes != 1)) {
+		error("Invalid num_stripes:sub_stripes %u:%u for profile %llu",
+		      num_stripes, sub_stripes,
+		      type & BTRFS_BLOCK_GROUP_PROFILE_MASK);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/*
+ * Get stripe length from chunk item and its stripe items
+ *
+ * Caller should only call this function after validating the chunk item
+ * by using btrfs_check_chunk_valid().
+ */
+u64 btrfs_stripe_length(struct btrfs_fs_info *fs_info,
+			struct extent_buffer *leaf,
+			struct btrfs_chunk *chunk)
+{
+	u64 stripe_len;
+	u64 chunk_len;
+	u32 num_stripes = btrfs_chunk_num_stripes(leaf, chunk);
+	u64 profile = btrfs_chunk_type(leaf, chunk) &
+		      BTRFS_BLOCK_GROUP_PROFILE_MASK;
+
+	chunk_len = btrfs_chunk_length(leaf, chunk);
+
+	switch (profile) {
+	case 0: /* Single profile */
+	case BTRFS_BLOCK_GROUP_RAID1:
+	case BTRFS_BLOCK_GROUP_RAID1C3:
+	case BTRFS_BLOCK_GROUP_RAID1C4:
+	case BTRFS_BLOCK_GROUP_DUP:
+		stripe_len = chunk_len;
+		break;
+	case BTRFS_BLOCK_GROUP_RAID0:
+		stripe_len = chunk_len / num_stripes;
+		break;
+	case BTRFS_BLOCK_GROUP_RAID5:
+		stripe_len = chunk_len / (num_stripes - 1);
+		break;
+	case BTRFS_BLOCK_GROUP_RAID6:
+		stripe_len = chunk_len / (num_stripes - 2);
+		break;
+	case BTRFS_BLOCK_GROUP_RAID10:
+		stripe_len = chunk_len / (num_stripes /
+				btrfs_chunk_sub_stripes(leaf, chunk));
+		break;
+	default:
+		/* Invalid chunk profile found */
+		BUG_ON(1);
+	}
+	return stripe_len;
+}
+
+int btrfs_num_copies(struct btrfs_fs_info *fs_info, u64 logical, u64 len)
+{
+	struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
+	struct cache_extent *ce;
+	struct map_lookup *map;
+	int ret;
+
+	ce = search_cache_extent(&map_tree->cache_tree, logical);
+	if (!ce) {
+		fprintf(stderr, "No mapping for %llu-%llu\n",
+			(unsigned long long)logical,
+			(unsigned long long)logical+len);
+		return 1;
+	}
+	if (ce->start > logical || ce->start + ce->size < logical) {
+		fprintf(stderr, "Invalid mapping for %llu-%llu, got "
+			"%llu-%llu\n", (unsigned long long)logical,
+			(unsigned long long)logical+len,
+			(unsigned long long)ce->start,
+			(unsigned long long)ce->start + ce->size);
+		return 1;
+	}
+	map = container_of(ce, struct map_lookup, ce);
+
+	if (map->type & (BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID1 |
+			 BTRFS_BLOCK_GROUP_RAID1C3 | BTRFS_BLOCK_GROUP_RAID1C4))
+		ret = map->num_stripes;
+	else if (map->type & BTRFS_BLOCK_GROUP_RAID10)
+		ret = map->sub_stripes;
+	else if (map->type & BTRFS_BLOCK_GROUP_RAID5)
+		ret = 2;
+	else if (map->type & BTRFS_BLOCK_GROUP_RAID6)
+		ret = 3;
+	else
+		ret = 1;
+	return ret;
+}
+
+int btrfs_next_bg(struct btrfs_fs_info *fs_info, u64 *logical,
+		  u64 *size, u64 type)
+{
+	struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
+	struct cache_extent *ce;
+	struct map_lookup *map;
+	u64 cur = *logical;
+
+	ce = search_cache_extent(&map_tree->cache_tree, cur);
+
+	while (ce) {
+		/*
+		 * only jump to next bg if our cur is not 0
+		 * As the initial logical for btrfs_next_bg() is 0, and
+		 * if we jump to next bg, we skipped a valid bg.
+		 */
+		if (cur) {
+			ce = next_cache_extent(ce);
+			if (!ce)
+				return -ENOENT;
+		}
+
+		cur = ce->start;
+		map = container_of(ce, struct map_lookup, ce);
+		if (map->type & type) {
+			*logical = ce->start;
+			*size = ce->size;
+			return 0;
+		}
+		if (!cur)
+			ce = next_cache_extent(ce);
+	}
+
+	return -ENOENT;
+}
+
+static inline int parity_smaller(u64 a, u64 b)
+{
+	return a > b;
+}
+
+/* Bubble-sort the stripe set to put the parity/syndrome stripes last */
+static void sort_parity_stripes(struct btrfs_multi_bio *bbio, u64 *raid_map)
+{
+	struct btrfs_bio_stripe s;
+	int i;
+	u64 l;
+	int again = 1;
+
+	while (again) {
+		again = 0;
+		for (i = 0; i < bbio->num_stripes - 1; i++) {
+			if (parity_smaller(raid_map[i], raid_map[i+1])) {
+				s = bbio->stripes[i];
+				l = raid_map[i];
+				bbio->stripes[i] = bbio->stripes[i+1];
+				raid_map[i] = raid_map[i+1];
+				bbio->stripes[i+1] = s;
+				raid_map[i+1] = l;
+				again = 1;
+			}
+		}
+	}
+}
+
+int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
+		      u64 logical, u64 *length, u64 *type,
+		      struct btrfs_multi_bio **multi_ret, int mirror_num,
+		      u64 **raid_map_ret)
+{
+	struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
+	struct cache_extent *ce;
+	struct map_lookup *map;
+	u64 offset;
+	u64 stripe_offset;
+	u64 *raid_map = NULL;
+	int stripe_nr;
+	int stripes_allocated = 8;
+	int stripes_required = 1;
+	int stripe_index;
+	int i;
+	struct btrfs_multi_bio *multi = NULL;
+
+	if (multi_ret && rw == READ) {
+		stripes_allocated = 1;
+	}
+again:
+	ce = search_cache_extent(&map_tree->cache_tree, logical);
+	if (!ce) {
+		kfree(multi);
+		*length = (u64)-1;
+		return -ENOENT;
+	}
+	if (ce->start > logical) {
+		kfree(multi);
+		*length = ce->start - logical;
+		return -ENOENT;
+	}
+
+	if (multi_ret) {
+		multi = kzalloc(btrfs_multi_bio_size(stripes_allocated),
+				GFP_NOFS);
+		if (!multi)
+			return -ENOMEM;
+	}
+	map = container_of(ce, struct map_lookup, ce);
+	offset = logical - ce->start;
+
+	if (rw == WRITE) {
+		if (map->type & (BTRFS_BLOCK_GROUP_RAID1 |
+				 BTRFS_BLOCK_GROUP_RAID1C3 |
+				 BTRFS_BLOCK_GROUP_RAID1C4 |
+				 BTRFS_BLOCK_GROUP_DUP)) {
+			stripes_required = map->num_stripes;
+		} else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
+			stripes_required = map->sub_stripes;
+		}
+	}
+	if (map->type & (BTRFS_BLOCK_GROUP_RAID5 | BTRFS_BLOCK_GROUP_RAID6)
+	    && multi_ret && ((rw & WRITE) || mirror_num > 1) && raid_map_ret) {
+		    /* RAID[56] write or recovery. Return all stripes */
+		    stripes_required = map->num_stripes;
+
+		    /* Only allocate the map if we've already got a large enough multi_ret */
+		    if (stripes_allocated >= stripes_required) {
+			    raid_map = kmalloc(sizeof(u64) * map->num_stripes, GFP_NOFS);
+			    if (!raid_map) {
+				    kfree(multi);
+				    return -ENOMEM;
+			    }
+		    }
+	}
+
+	/* if our multi bio struct is too small, back off and try again */
+	if (multi_ret && stripes_allocated < stripes_required) {
+		stripes_allocated = stripes_required;
+		kfree(multi);
+		multi = NULL;
+		goto again;
+	}
+	stripe_nr = offset;
+	/*
+	 * stripe_nr counts the total number of stripes we have to stride
+	 * to get to this block
+	 */
+	stripe_nr = stripe_nr / map->stripe_len;
+
+	stripe_offset = stripe_nr * map->stripe_len;
+	BUG_ON(offset < stripe_offset);
+
+	/* stripe_offset is the offset of this block in its stripe*/
+	stripe_offset = offset - stripe_offset;
+
+	if (map->type & (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
+			 BTRFS_BLOCK_GROUP_RAID1C3 | BTRFS_BLOCK_GROUP_RAID1C4 |
+			 BTRFS_BLOCK_GROUP_RAID5 | BTRFS_BLOCK_GROUP_RAID6 |
+			 BTRFS_BLOCK_GROUP_RAID10 |
+			 BTRFS_BLOCK_GROUP_DUP)) {
+		/* we limit the length of each bio to what fits in a stripe */
+		*length = min_t(u64, ce->size - offset,
+			      map->stripe_len - stripe_offset);
+	} else {
+		*length = ce->size - offset;
+	}
+
+	if (!multi_ret)
+		goto out;
+
+	multi->num_stripes = 1;
+	stripe_index = 0;
+	if (map->type & (BTRFS_BLOCK_GROUP_RAID1 |
+			 BTRFS_BLOCK_GROUP_RAID1C3 |
+			 BTRFS_BLOCK_GROUP_RAID1C4)) {
+		if (rw == WRITE)
+			multi->num_stripes = map->num_stripes;
+		else if (mirror_num)
+			stripe_index = mirror_num - 1;
+		else
+			stripe_index = stripe_nr % map->num_stripes;
+	} else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
+		int factor = map->num_stripes / map->sub_stripes;
+
+		stripe_index = stripe_nr % factor;
+		stripe_index *= map->sub_stripes;
+
+		if (rw == WRITE)
+			multi->num_stripes = map->sub_stripes;
+		else if (mirror_num)
+			stripe_index += mirror_num - 1;
+
+		stripe_nr = stripe_nr / factor;
+	} else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
+		if (rw == WRITE)
+			multi->num_stripes = map->num_stripes;
+		else if (mirror_num)
+			stripe_index = mirror_num - 1;
+	} else if (map->type & (BTRFS_BLOCK_GROUP_RAID5 |
+				BTRFS_BLOCK_GROUP_RAID6)) {
+
+		if (raid_map) {
+			int rot;
+			u64 tmp;
+			u64 raid56_full_stripe_start;
+			u64 full_stripe_len = nr_data_stripes(map) * map->stripe_len;
+
+			/*
+			 * align the start of our data stripe in the logical
+			 * address space
+			 */
+			raid56_full_stripe_start = offset / full_stripe_len;
+			raid56_full_stripe_start *= full_stripe_len;
+
+			/* get the data stripe number */
+			stripe_nr = raid56_full_stripe_start / map->stripe_len;
+			stripe_nr = stripe_nr / nr_data_stripes(map);
+
+			/* Work out the disk rotation on this stripe-set */
+			rot = stripe_nr % map->num_stripes;
+
+			/* Fill in the logical address of each stripe */
+			tmp = stripe_nr * nr_data_stripes(map);
+
+			for (i = 0; i < nr_data_stripes(map); i++)
+				raid_map[(i+rot) % map->num_stripes] =
+					ce->start + (tmp + i) * map->stripe_len;
+
+			raid_map[(i+rot) % map->num_stripes] = BTRFS_RAID5_P_STRIPE;
+			if (map->type & BTRFS_BLOCK_GROUP_RAID6)
+				raid_map[(i+rot+1) % map->num_stripes] = BTRFS_RAID6_Q_STRIPE;
+
+			*length = map->stripe_len;
+			stripe_index = 0;
+			stripe_offset = 0;
+			multi->num_stripes = map->num_stripes;
+		} else {
+			stripe_index = stripe_nr % nr_data_stripes(map);
+			stripe_nr = stripe_nr / nr_data_stripes(map);
+
+			/*
+			 * Mirror #0 or #1 means the original data block.
+			 * Mirror #2 is RAID5 parity block.
+			 * Mirror #3 is RAID6 Q block.
+			 */
+			if (mirror_num > 1)
+				stripe_index = nr_data_stripes(map) + mirror_num - 2;
+
+			/* We distribute the parity blocks across stripes */
+			stripe_index = (stripe_nr + stripe_index) % map->num_stripes;
+		}
+	} else {
+		/*
+		 * after this do_div call, stripe_nr is the number of stripes
+		 * on this device we have to walk to find the data, and
+		 * stripe_index is the number of our device in the stripe array
+		 */
+		stripe_index = stripe_nr % map->num_stripes;
+		stripe_nr = stripe_nr / map->num_stripes;
+	}
+	BUG_ON(stripe_index >= map->num_stripes);
+
+	for (i = 0; i < multi->num_stripes; i++) {
+		multi->stripes[i].physical =
+			map->stripes[stripe_index].physical + stripe_offset +
+			stripe_nr * map->stripe_len;
+		multi->stripes[i].dev = map->stripes[stripe_index].dev;
+		stripe_index++;
+	}
+	*multi_ret = multi;
+
+	if (type)
+		*type = map->type;
+
+	if (raid_map) {
+		sort_parity_stripes(multi, raid_map);
+		*raid_map_ret = raid_map;
+	}
+out:
+	return 0;
+}
+
+int btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
+		    u64 logical, u64 *length,
+		    struct btrfs_multi_bio **multi_ret, int mirror_num,
+		    u64 **raid_map_ret)
+{
+	return __btrfs_map_block(fs_info, rw, logical, length, NULL,
+				 multi_ret, mirror_num, raid_map_ret);
+}
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
new file mode 100644
index 000000000000..4383b4f9c034
--- /dev/null
+++ b/fs/btrfs/volumes.h
@@ -0,0 +1,202 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#ifndef __BTRFS_VOLUMES_H__
+#define __BTRFS_VOLUMES_H__
+
+#include <fs_internal.h>
+#include "ctree.h"
+
+#define BTRFS_STRIPE_LEN	SZ_64K
+
+struct btrfs_device {
+	struct list_head dev_list;
+	struct btrfs_root *dev_root;
+	struct btrfs_fs_devices *fs_devices;
+
+	struct blk_desc *desc;
+	disk_partition_t *part;
+
+	u64 total_devs;
+	u64 super_bytes_used;
+
+	u64 generation;
+
+	/* the internal btrfs device id */
+	u64 devid;
+
+	/* size of the device */
+	u64 total_bytes;
+
+	/* bytes used */
+	u64 bytes_used;
+
+	/* optimal io alignment for this device */
+	u32 io_align;
+
+	/* optimal io width for this device */
+	u32 io_width;
+
+	/* minimal io size for this device */
+	u32 sector_size;
+
+	/* type and info about this device */
+	u64 type;
+
+	/* physical drive uuid (or lvm uuid) */
+	u8 uuid[BTRFS_UUID_SIZE];
+};
+
+struct btrfs_fs_devices {
+	u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */
+	u8 metadata_uuid[BTRFS_FSID_SIZE]; /* FS specific uuid */
+
+	u64 latest_devid;
+	u64 lowest_devid;
+	u64 latest_trans;
+
+	u64 total_rw_bytes;
+
+	struct list_head devices;
+	struct list_head list;
+
+	int seeding;
+	struct btrfs_fs_devices *seed;
+};
+
+struct btrfs_bio_stripe {
+	struct btrfs_device *dev;
+	u64 physical;
+};
+
+struct btrfs_multi_bio {
+	int error;
+	int num_stripes;
+	struct btrfs_bio_stripe stripes[];
+};
+
+struct map_lookup {
+	struct cache_extent ce;
+	u64 type;
+	int io_align;
+	int io_width;
+	int stripe_len;
+	int sector_size;
+	int num_stripes;
+	int sub_stripes;
+	struct btrfs_bio_stripe stripes[];
+};
+
+struct btrfs_raid_attr {
+	int sub_stripes;	/* sub_stripes info for map */
+	int dev_stripes;	/* stripes per dev */
+	int devs_max;		/* max devs to use */
+	int devs_min;		/* min devs needed */
+	int tolerated_failures; /* max tolerated fail devs */
+	int devs_increment;	/* ndevs has to be a multiple of this */
+	int ncopies;		/* how many copies to data has */
+	int nparity;		/* number of stripes worth of bytes to store
+				 * parity information */
+	const char raid_name[8]; /* name of the raid */
+	u64 bg_flag;		/* block group flag of the raid */
+};
+
+extern const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES];
+
+static inline enum btrfs_raid_types btrfs_bg_flags_to_raid_index(u64 flags)
+{
+	if (flags & BTRFS_BLOCK_GROUP_RAID10)
+		return BTRFS_RAID_RAID10;
+	else if (flags & BTRFS_BLOCK_GROUP_RAID1)
+		return BTRFS_RAID_RAID1;
+	else if (flags & BTRFS_BLOCK_GROUP_RAID1C3)
+		return BTRFS_RAID_RAID1C3;
+	else if (flags & BTRFS_BLOCK_GROUP_RAID1C4)
+		return BTRFS_RAID_RAID1C4;
+	else if (flags & BTRFS_BLOCK_GROUP_DUP)
+		return BTRFS_RAID_DUP;
+	else if (flags & BTRFS_BLOCK_GROUP_RAID0)
+		return BTRFS_RAID_RAID0;
+	else if (flags & BTRFS_BLOCK_GROUP_RAID5)
+		return BTRFS_RAID_RAID5;
+	else if (flags & BTRFS_BLOCK_GROUP_RAID6)
+		return BTRFS_RAID_RAID6;
+
+	return BTRFS_RAID_SINGLE; /* BTRFS_BLOCK_GROUP_SINGLE */
+}
+
+#define btrfs_multi_bio_size(n) (sizeof(struct btrfs_multi_bio) + \
+			    (sizeof(struct btrfs_bio_stripe) * (n)))
+#define btrfs_map_lookup_size(n) (sizeof(struct map_lookup) + \
+				 (sizeof(struct btrfs_bio_stripe) * (n)))
+
+#define BTRFS_RAID5_P_STRIPE ((u64)-2)
+#define BTRFS_RAID6_Q_STRIPE ((u64)-1)
+
+static inline u64 calc_stripe_length(u64 type, u64 length, int num_stripes)
+{
+	u64 stripe_size;
+
+	if (type & BTRFS_BLOCK_GROUP_RAID0) {
+		stripe_size = length;
+		stripe_size /= num_stripes;
+	} else if (type & BTRFS_BLOCK_GROUP_RAID10) {
+		stripe_size = length * 2;
+		stripe_size /= num_stripes;
+	} else if (type & BTRFS_BLOCK_GROUP_RAID5) {
+		stripe_size = length;
+		stripe_size /= (num_stripes - 1);
+	} else if (type & BTRFS_BLOCK_GROUP_RAID6) {
+		stripe_size = length;
+		stripe_size /= (num_stripes - 2);
+	} else {
+		stripe_size = length;
+	}
+	return stripe_size;
+}
+
+#ifndef READ
+#define READ 0
+#define WRITE 1
+#define READA 2
+#endif
+
+int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
+		      u64 logical, u64 *length, u64 *type,
+		      struct btrfs_multi_bio **multi_ret, int mirror_num,
+		      u64 **raid_map);
+int btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
+		    u64 logical, u64 *length,
+		    struct btrfs_multi_bio **multi_ret, int mirror_num,
+		    u64 **raid_map_ret);
+int btrfs_next_bg(struct btrfs_fs_info *map_tree, u64 *logical,
+		     u64 *size, u64 type);
+static inline int btrfs_next_bg_metadata(struct btrfs_fs_info *fs_info,
+					 u64 *logical, u64 *size)
+{
+	return btrfs_next_bg(fs_info, logical, size,
+			BTRFS_BLOCK_GROUP_METADATA);
+}
+static inline int btrfs_next_bg_system(struct btrfs_fs_info *fs_info,
+				       u64 *logical, u64 *size)
+{
+	return btrfs_next_bg(fs_info, logical, size,
+			BTRFS_BLOCK_GROUP_SYSTEM);
+}
+int btrfs_open_devices(struct btrfs_fs_devices *fs_devices);
+int btrfs_close_devices(struct btrfs_fs_devices *fs_devices);
+void btrfs_close_all_devices(void);
+int btrfs_num_copies(struct btrfs_fs_info *fs_info, u64 logical, u64 len);
+int btrfs_scan_one_device(struct blk_desc *desc, disk_partition_t *part,
+			  struct btrfs_fs_devices **fs_devices_ret,
+			  u64 *total_devs);
+struct list_head *btrfs_scanned_uuids(void);
+struct btrfs_device *btrfs_find_device(struct btrfs_fs_info *fs_info, u64 devid,
+				       u8 *uuid, u8 *fsid);
+int btrfs_check_chunk_valid(struct btrfs_fs_info *fs_info,
+			    struct extent_buffer *leaf,
+			    struct btrfs_chunk *chunk,
+			    int slot, u64 logical);
+u64 btrfs_stripe_length(struct btrfs_fs_info *fs_info,
+			struct extent_buffer *leaf,
+			struct btrfs_chunk *chunk);
+#endif
