struct scrub_ctx {
        struct scrub_bio        *bios[SCRUB_BIOS_PER_SCTX];
-       struct btrfs_root       *dev_root;
+       struct btrfs_fs_info    *fs_info;
        int                     first_free;
        int                     curr;
        atomic_t                bios_in_flight;
  */
 static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx)
 {
-       struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
+       struct btrfs_fs_info *fs_info = sctx->fs_info;
 
        atomic_inc(&sctx->refs);
        /*
 /* used for workers that require transaction commits */
 static void scrub_pending_trans_workers_dec(struct scrub_ctx *sctx)
 {
-       struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
+       struct btrfs_fs_info *fs_info = sctx->fs_info;
 
        /*
         * see scrub_pending_trans_workers_inc() why we're pretending
 {
        struct scrub_ctx *sctx;
        int             i;
-       struct btrfs_fs_info *fs_info = dev->dev_root->fs_info;
+       struct btrfs_fs_info *fs_info = dev->fs_info;
        int ret;
 
        sctx = kzalloc(sizeof(*sctx), GFP_KERNEL);
        sctx->is_dev_replace = is_dev_replace;
        sctx->pages_per_rd_bio = SCRUB_PAGES_PER_RD_BIO;
        sctx->curr = -1;
-       sctx->dev_root = dev->dev_root;
+       sctx->fs_info = dev->fs_info;
        for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
                struct scrub_bio *sbio;
 
                        sctx->bios[i]->next_free = -1;
        }
        sctx->first_free = 0;
-       sctx->nodesize = dev->dev_root->nodesize;
-       sctx->sectorsize = dev->dev_root->sectorsize;
+       sctx->nodesize = dev->fs_info->dev_root->nodesize;
+       sctx->sectorsize = dev->fs_info->dev_root->sectorsize;
        atomic_set(&sctx->bios_in_flight, 0);
        atomic_set(&sctx->workers_pending, 0);
        atomic_set(&sctx->cancel_req, 0);
        struct extent_buffer *eb;
        struct btrfs_inode_item *inode_item;
        struct scrub_warning *swarn = warn_ctx;
-       struct btrfs_fs_info *fs_info = swarn->dev->dev_root->fs_info;
+       struct btrfs_fs_info *fs_info = swarn->dev->fs_info;
        struct inode_fs_paths *ipath = NULL;
        struct btrfs_root *local_root;
        struct btrfs_key root_key;
 
        WARN_ON(sblock->page_count < 1);
        dev = sblock->pagev[0]->dev;
-       fs_info = sblock->sctx->dev_root->fs_info;
+       fs_info = sblock->sctx->fs_info;
 
        path = btrfs_alloc_path();
        if (!path)
                spin_lock(&sctx->stat_lock);
                ++sctx->stat.uncorrectable_errors;
                spin_unlock(&sctx->stat_lock);
-               btrfs_dev_replace_stats_inc(
-                       &sctx->dev_root->fs_info->dev_replace.
-                       num_uncorrectable_read_errors);
-               btrfs_err_rl_in_rcu(sctx->dev_root->fs_info,
+               btrfs_dev_replace_stats_inc(&sctx->fs_info->dev_replace.
+                                               num_uncorrectable_read_errors);
+               btrfs_err_rl_in_rcu(sctx->fs_info,
                    "unable to fixup (nodatasum) error at logical %llu on dev %s",
                        fixup->logical, rcu_str_deref(fixup->dev->name));
        }
                                      DEFAULT_RATELIMIT_BURST);
 
        BUG_ON(sblock_to_check->page_count < 1);
-       fs_info = sctx->dev_root->fs_info;
+       fs_info = sctx->fs_info;
        if (sblock_to_check->pagev[0]->flags & BTRFS_EXTENT_FLAG_SUPER) {
                /*
                 * if we find an error in a super block, we just report it.
                        if (scrub_write_page_to_dev_replace(sblock_other,
                                                            page_num) != 0) {
                                btrfs_dev_replace_stats_inc(
-                                       &sctx->dev_root->
-                                       fs_info->dev_replace.
+                                       &sctx->fs_info->dev_replace.
                                        num_write_errors);
                                success = 0;
                        }
                                     struct scrub_block *sblocks_for_recheck)
 {
        struct scrub_ctx *sctx = original_sblock->sctx;
-       struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
+       struct btrfs_fs_info *fs_info = sctx->fs_info;
        u64 length = original_sblock->page_count * PAGE_SIZE;
        u64 logical = original_sblock->pagev[0]->logical;
        u64 generation = original_sblock->pagev[0]->generation;
                int ret;
 
                if (!page_bad->dev->bdev) {
-                       btrfs_warn_rl(sblock_bad->sctx->dev_root->fs_info,
+                       btrfs_warn_rl(sblock_bad->sctx->fs_info,
                                "scrub_repair_page_from_good_copy(bdev == NULL) is unexpected");
                        return -EIO;
                }
                        btrfs_dev_stat_inc_and_print(page_bad->dev,
                                BTRFS_DEV_STAT_WRITE_ERRS);
                        btrfs_dev_replace_stats_inc(
-                               &sblock_bad->sctx->dev_root->fs_info->
+                               &sblock_bad->sctx->fs_info->
                                dev_replace.num_write_errors);
                        bio_put(bio);
                        return -EIO;
                ret = scrub_write_page_to_dev_replace(sblock, page_num);
                if (ret)
                        btrfs_dev_replace_stats_inc(
-                               &sblock->sctx->dev_root->fs_info->dev_replace.
+                               &sblock->sctx->fs_info->dev_replace.
                                num_write_errors);
        }
 }
 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->dev_root->fs_info;
+       struct btrfs_fs_info *fs_info = sbio->dev->fs_info;
 
        sbio->err = bio->bi_error;
        sbio->bio = bio;
        WARN_ON(sbio->page_count > SCRUB_PAGES_PER_WR_BIO);
        if (sbio->err) {
                struct btrfs_dev_replace *dev_replace =
-                       &sbio->sctx->dev_root->fs_info->dev_replace;
+                       &sbio->sctx->fs_info->dev_replace;
 
                for (i = 0; i < sbio->page_count; i++) {
                        struct scrub_page *spage = sbio->pagev[i];
 {
        struct scrub_ctx *sctx = sblock->sctx;
        struct btrfs_header *h;
-       struct btrfs_root *root = sctx->dev_root;
+       struct btrfs_root *root = sctx->fs_info->dev_root;
        struct btrfs_fs_info *fs_info = root->fs_info;
        u8 calculated_csum[BTRFS_CSUM_SIZE];
        u8 on_disk_csum[BTRFS_CSUM_SIZE];
 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->dev_root->fs_info;
+       struct btrfs_fs_info *fs_info = sblock->sctx->fs_info;
 
        if (bio->bi_error)
                sblock->no_io_error_seen = 0;
                spin_lock(&sctx->stat_lock);
                sctx->stat.read_errors++;
                spin_unlock(&sctx->stat_lock);
-               btrfs_err_rl_in_rcu(sctx->dev_root->fs_info,
+               btrfs_err_rl_in_rcu(sctx->fs_info,
                        "IO error rebuilding logical %llu for dev %s",
                        logical, rcu_str_deref(dev->name));
        } else if (sblock->header_error || sblock->checksum_error) {
                spin_lock(&sctx->stat_lock);
                sctx->stat.uncorrectable_errors++;
                spin_unlock(&sctx->stat_lock);
-               btrfs_err_rl_in_rcu(sctx->dev_root->fs_info,
+               btrfs_err_rl_in_rcu(sctx->fs_info,
                        "failed to rebuild valid logical %llu for dev %s",
                        logical, rcu_str_deref(dev->name));
        } else {
 static void scrub_missing_raid56_pages(struct scrub_block *sblock)
 {
        struct scrub_ctx *sctx = sblock->sctx;
-       struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
+       struct btrfs_fs_info *fs_info = sctx->fs_info;
+       struct btrfs_root *dev_root = fs_info->dev_root;
        u64 length = sblock->page_count * PAGE_SIZE;
        u64 logical = sblock->pagev[0]->logical;
        struct btrfs_bio *bbio = NULL;
        bio->bi_private = sblock;
        bio->bi_end_io = scrub_missing_raid56_end_io;
 
-       rbio = raid56_alloc_missing_rbio(sctx->dev_root, bio, bbio, length);
+       rbio = raid56_alloc_missing_rbio(dev_root, bio, bbio, length);
        if (!rbio)
                goto rbio_out;
 
 static void scrub_bio_end_io(struct bio *bio)
 {
        struct scrub_bio *sbio = bio->bi_private;
-       struct btrfs_fs_info *fs_info = sbio->dev->dev_root->fs_info;
+       struct btrfs_fs_info *fs_info = sbio->dev->fs_info;
 
        sbio->err = bio->bi_error;
        sbio->bio = bio;
 {
        u32 offset;
        int nsectors;
-       int sectorsize = sparity->sctx->dev_root->sectorsize;
+       int sectorsize = sparity->sctx->fs_info->dev_root->sectorsize;
 
        if (len >= sparity->stripe_len) {
                bitmap_set(bitmap, 0, sparity->nsectors);
 
        btrfs_init_work(&sparity->work, btrfs_scrubparity_helper,
                        scrub_parity_bio_endio_worker, NULL, NULL);
-       btrfs_queue_work(sparity->sctx->dev_root->fs_info->scrub_parity_workers,
+       btrfs_queue_work(sparity->sctx->fs_info->scrub_parity_workers,
                         &sparity->work);
 }
 
 static void scrub_parity_check_and_repair(struct scrub_parity *sparity)
 {
        struct scrub_ctx *sctx = sparity->sctx;
+       struct btrfs_root *dev_root = sctx->fs_info->dev_root;
        struct bio *bio;
        struct btrfs_raid_bio *rbio;
        struct scrub_page *spage;
                goto out;
 
        length = sparity->logic_end - sparity->logic_start;
-       ret = btrfs_map_sblock(sctx->dev_root->fs_info, BTRFS_MAP_WRITE,
+       ret = btrfs_map_sblock(sctx->fs_info, BTRFS_MAP_WRITE,
                               sparity->logic_start,
                               &length, &bbio, 0, 1);
        if (ret || !bbio || !bbio->raid_map)
        bio->bi_private = sparity;
        bio->bi_end_io = scrub_parity_bio_endio;
 
-       rbio = raid56_parity_alloc_scrub_rbio(sctx->dev_root, bio, bbio,
+       rbio = raid56_parity_alloc_scrub_rbio(dev_root, bio, bbio,
                                              length, sparity->scrub_dev,
                                              sparity->dbitmap,
                                              sparity->nsectors);
                                                  u64 logic_start,
                                                  u64 logic_end)
 {
-       struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
+       struct btrfs_fs_info *fs_info = sctx->fs_info;
        struct btrfs_root *root = fs_info->extent_root;
        struct btrfs_root *csum_root = fs_info->csum_root;
        struct btrfs_extent_item *extent;
                                           int is_dev_replace)
 {
        struct btrfs_path *path, *ppath;
-       struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
+       struct btrfs_fs_info *fs_info = sctx->fs_info;
        struct btrfs_root *root = fs_info->extent_root;
        struct btrfs_root *csum_root = fs_info->csum_root;
        struct btrfs_extent_item *extent;
                                          struct btrfs_block_group_cache *cache,
                                          int is_dev_replace)
 {
-       struct btrfs_mapping_tree *map_tree =
-               &sctx->dev_root->fs_info->mapping_tree;
+       struct btrfs_fs_info *fs_info = sctx->fs_info;
+       struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
        struct map_lookup *map;
        struct extent_map *em;
        int i;
 {
        struct btrfs_dev_extent *dev_extent = NULL;
        struct btrfs_path *path;
-       struct btrfs_root *root = sctx->dev_root;
+       struct btrfs_root *root = sctx->fs_info->dev_root;
        struct btrfs_fs_info *fs_info = root->fs_info;
        u64 length;
        u64 chunk_offset;
        u64     bytenr;
        u64     gen;
        int     ret;
-       struct btrfs_root *root = sctx->dev_root;
+       struct btrfs_root *root = sctx->fs_info->dev_root;
 
        if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state))
                return -EIO;
                            int mirror_num, u64 physical_for_dev_replace)
 {
        struct scrub_copy_nocow_ctx *nocow_ctx;
-       struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
+       struct btrfs_fs_info *fs_info = sctx->fs_info;
 
        nocow_ctx = kzalloc(sizeof(*nocow_ctx), GFP_NOFS);
        if (!nocow_ctx) {
        struct btrfs_root *root;
        int not_written = 0;
 
-       fs_info = sctx->dev_root->fs_info;
+       fs_info = sctx->fs_info;
        root = fs_info->extent_root;
 
        path = btrfs_alloc_path();
 static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root,
                                      struct scrub_copy_nocow_ctx *nocow_ctx)
 {
-       struct btrfs_fs_info *fs_info = nocow_ctx->sctx->dev_root->fs_info;
+       struct btrfs_fs_info *fs_info = nocow_ctx->sctx->fs_info;
        struct btrfs_key key;
        struct inode *inode;
        struct page *page;
        if (!dev)
                return -EIO;
        if (!dev->bdev) {
-               btrfs_warn_rl(dev->dev_root->fs_info,
+               btrfs_warn_rl(dev->fs_info,
                        "scrub write_page_nocow(bdev == NULL) is unexpected");
                return -EIO;
        }
 
        blk_start_plug(&plug);
 
        bdi = blk_get_backing_dev_info(device->bdev);
-       fs_info = device->dev_root->fs_info;
+       fs_info = device->fs_info;
        limit = btrfs_async_submit_limit(fs_info);
        limit = limit * 2 / 3;
 
                                   u64 end, u64 *length)
 {
        struct btrfs_key key;
-       struct btrfs_root *root = device->dev_root;
+       struct btrfs_root *root = device->fs_info->dev_root;
        struct btrfs_dev_extent *dev_extent;
        struct btrfs_path *path;
        u64 extent_end;
                                   struct btrfs_device *device,
                                   u64 *start, u64 len)
 {
-       struct btrfs_fs_info *fs_info = device->dev_root->fs_info;
+       struct btrfs_fs_info *fs_info = device->fs_info;
        struct extent_map *em;
        struct list_head *search_list = &fs_info->pinned_chunks;
        int ret = 0;
                               struct btrfs_device *device, u64 num_bytes,
                               u64 search_start, u64 *start, u64 *len)
 {
+       struct btrfs_root *root = device->fs_info->dev_root;
        struct btrfs_key key;
-       struct btrfs_root *root = device->dev_root;
        struct btrfs_dev_extent *dev_extent;
        struct btrfs_path *path;
        u64 hole_size;
                          struct btrfs_device *device,
                          u64 start, u64 *dev_extent_len)
 {
+       struct btrfs_root *root = device->fs_info->dev_root;
        int ret;
        struct btrfs_path *path;
-       struct btrfs_root *root = device->dev_root;
        struct btrfs_key key;
        struct btrfs_key found_key;
        struct extent_buffer *leaf = NULL;
 {
        int ret;
        struct btrfs_path *path;
-       struct btrfs_root *root = device->dev_root;
+       struct btrfs_root *root = device->fs_info->dev_root;
        struct btrfs_dev_extent *extent;
        struct extent_buffer *leaf;
        struct btrfs_key key;
        device->total_bytes = i_size_read(bdev->bd_inode);
        device->disk_total_bytes = device->total_bytes;
        device->commit_total_bytes = device->total_bytes;
-       device->dev_root = root->fs_info->dev_root;
+       device->fs_info = fs_info;
        device->bdev = bdev;
        device->in_fs_metadata = 1;
        device->is_tgtdev_for_dev_replace = 0;
        ASSERT(list_empty(&srcdev->resized_list));
        device->commit_total_bytes = srcdev->commit_total_bytes;
        device->commit_bytes_used = device->bytes_used;
-       device->dev_root = fs_info->dev_root;
+       device->fs_info = fs_info;
        device->bdev = bdev;
        device->in_fs_metadata = 1;
        device->is_tgtdev_for_dev_replace = 1;
        tgtdev->io_width = fs_info->dev_root->sectorsize;
        tgtdev->io_align = fs_info->dev_root->sectorsize;
        tgtdev->sector_size = fs_info->dev_root->sectorsize;
-       tgtdev->dev_root = fs_info->dev_root;
+       tgtdev->fs_info = fs_info;
        tgtdev->in_fs_metadata = 1;
 }
 
        struct extent_buffer *leaf;
        struct btrfs_key key;
 
-       root = device->dev_root->fs_info->chunk_root;
+       root = device->fs_info->chunk_root;
 
        path = btrfs_alloc_path();
        if (!path)
 int btrfs_grow_device(struct btrfs_trans_handle *trans,
                      struct btrfs_device *device, u64 new_size)
 {
-       struct btrfs_super_block *super_copy =
-               device->dev_root->fs_info->super_copy;
+       struct btrfs_super_block *super_copy = device->fs_info->super_copy;
        struct btrfs_fs_devices *fs_devices;
        u64 old_total;
        u64 diff;
        if (!device->writeable)
                return -EACCES;
 
-       lock_chunks(device->dev_root);
+       lock_chunks(device->fs_info->dev_root);
        old_total = btrfs_super_total_bytes(super_copy);
        diff = new_size - device->total_bytes;
 
        if (new_size <= device->total_bytes ||
            device->is_tgtdev_for_dev_replace) {
-               unlock_chunks(device->dev_root);
+               unlock_chunks(device->fs_info->dev_root);
                return -EINVAL;
        }
 
-       fs_devices = device->dev_root->fs_info->fs_devices;
+       fs_devices = device->fs_info->fs_devices;
 
        btrfs_set_super_total_bytes(super_copy, old_total + diff);
        device->fs_devices->total_rw_bytes += diff;
 
        btrfs_device_set_total_bytes(device, new_size);
        btrfs_device_set_disk_total_bytes(device, new_size);
-       btrfs_clear_space_info_full(device->dev_root->fs_info);
+       btrfs_clear_space_info_full(device->fs_info);
        if (list_empty(&device->resized_list))
                list_add_tail(&device->resized_list,
                              &fs_devices->resized_devices);
-       unlock_chunks(device->dev_root);
+       unlock_chunks(device->fs_info->dev_root);
 
        return btrfs_update_device(trans, device);
 }
 int btrfs_shrink_device(struct btrfs_device *device, u64 new_size)
 {
        struct btrfs_trans_handle *trans;
-       struct btrfs_root *root = device->dev_root;
+       struct btrfs_root *root = device->fs_info->dev_root;
        struct btrfs_dev_extent *dev_extent = NULL;
        struct btrfs_path *path;
        u64 length;
        while (fs_devices) {
                mutex_lock(&fs_devices->device_list_mutex);
                list_for_each_entry(device, &fs_devices->devices, dev_list)
-                       device->dev_root = fs_info->dev_root;
+                       device->fs_info = fs_info;
                mutex_unlock(&fs_devices->device_list_mutex);
 
                fs_devices = fs_devices->seed;
 {
        if (!dev->dev_stats_valid)
                return;
-       btrfs_err_rl_in_rcu(dev->dev_root->fs_info,
+       btrfs_err_rl_in_rcu(dev->fs_info,
                "bdev %s errs: wr %u, rd %u, flush %u, corrupt %u, gen %u",
                           rcu_str_deref(dev->name),
                           btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_WRITE_ERRS),
        if (i == BTRFS_DEV_STAT_VALUES_MAX)
                return; /* all values == 0, suppress message */
 
-       btrfs_info_in_rcu(dev->dev_root->fs_info,
+       btrfs_info_in_rcu(dev->fs_info,
                "bdev %s errs: wr %u, rd %u, flush %u, corrupt %u, gen %u",
               rcu_str_deref(dev->name),
               btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_WRITE_ERRS),