Btrfs: remove device tree

Signed-off-by: Chris Mason <chris.mason@oracle.com>

4 files changed, 10 insertions, 413 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index e93ba1a5c812..5ab25a0cb16a 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -16,11 +16,10 @@ extern struct kmem_cache *btrfs_path_cachep;
 #define BTRFS_MAGIC "_BtRfS_M"
 
 #define BTRFS_ROOT_TREE_OBJECTID 1ULL
-#define BTRFS_DEV_TREE_OBJECTID 2ULL
-#define BTRFS_EXTENT_TREE_OBJECTID 3ULL
-#define BTRFS_FS_TREE_OBJECTID 4ULL
-#define BTRFS_ROOT_TREE_DIR_OBJECTID 5ULL
-#define BTRFS_FIRST_FREE_OBJECTID 6ULL
+#define BTRFS_EXTENT_TREE_OBJECTID 2ULL
+#define BTRFS_FS_TREE_OBJECTID 3ULL
+#define BTRFS_ROOT_TREE_DIR_OBJECTID 4ULL
+#define BTRFS_FIRST_FREE_OBJECTID 5ULL
 
 /*
  * we can actually store much bigger names, but lets not confuse the rest
@@ -111,12 +110,6 @@ struct btrfs_super_block {
         __le64 total_blocks;
         __le64 blocks_used;
         __le64 root_dir_objectid;
-        __le64 last_device_id;
-        /* fields below here vary with the underlying disk */
-        __le64 device_block_start;
-        __le64 device_num_blocks;
-        __le64 device_root;
-        __le64 device_id;
 } __attribute__ ((__packed__));
 
 /*
@@ -251,11 +244,6 @@ struct btrfs_csum_item {
         u8 csum;
 } __attribute__ ((__packed__));
 
-struct btrfs_device_item {
-        __le16 pathlen;
-        __le64 device_id;
-} __attribute__ ((__packed__));
-
 /* tag for the radix tree of block groups in ram */
 #define BTRFS_BLOCK_GROUP_DIRTY 0
 #define BTRFS_BLOCK_GROUP_AVAIL 1
@@ -286,11 +274,9 @@ struct btrfs_fs_info {
         spinlock_t hash_lock;
         struct btrfs_root *extent_root;
         struct btrfs_root *tree_root;
-        struct btrfs_root *dev_root;
         struct radix_tree_root fs_roots_radix;
         struct radix_tree_root pending_del_radix;
         struct radix_tree_root pinned_radix;
-        struct radix_tree_root dev_radix;
         struct radix_tree_root block_group_radix;
         struct radix_tree_root block_group_data_radix;
         struct radix_tree_root extent_map_radix;
@@ -386,11 +372,6 @@ struct btrfs_root {
 #define BTRFS_BLOCK_GROUP_ITEM_KEY 34
 
 /*
- * dev items list the devices that make up the FS
- */
-#define BTRFS_DEV_ITEM_KEY      35
-
-/*
  * string items are for debugging.  They just store a short string of
  * data in the FS
  */
@@ -880,62 +861,6 @@ static inline void btrfs_set_super_root_dir(struct btrfs_super_block *s, u64
         s->root_dir_objectid = cpu_to_le64(val);
 }
 
-static inline u64 btrfs_super_last_device_id(struct btrfs_super_block *s)
-{
-        return le64_to_cpu(s->last_device_id);
-}
-
-static inline void btrfs_set_super_last_device_id(struct btrfs_super_block *s,
-                                                  u64 val)
-{
-        s->last_device_id = cpu_to_le64(val);
-}
-
-static inline u64 btrfs_super_device_id(struct btrfs_super_block *s)
-{
-        return le64_to_cpu(s->device_id);
-}
-
-static inline void btrfs_set_super_device_id(struct btrfs_super_block *s,
-                                                  u64 val)
-{
-        s->device_id = cpu_to_le64(val);
-}
-
-static inline u64 btrfs_super_device_block_start(struct btrfs_super_block *s)
-{
-        return le64_to_cpu(s->device_block_start);
-}
-
-static inline void btrfs_set_super_device_block_start(struct btrfs_super_block
-                                                      *s, u64 val)
-{
-        s->device_block_start = cpu_to_le64(val);
-}
-
-static inline u64 btrfs_super_device_num_blocks(struct btrfs_super_block *s)
-{
-        return le64_to_cpu(s->device_num_blocks);
-}
-
-static inline void btrfs_set_super_device_num_blocks(struct btrfs_super_block
-                                                     *s, u64 val)
-{
-        s->device_num_blocks = cpu_to_le64(val);
-}
-
-static inline u64 btrfs_super_device_root(struct btrfs_super_block *s)
-{
-        return le64_to_cpu(s->device_root);
-}
-
-static inline void btrfs_set_super_device_root(struct btrfs_super_block
-                                                      *s, u64 val)
-{
-        s->device_root = cpu_to_le64(val);
-}
-
-
 static inline u8 *btrfs_leaf_data(struct btrfs_leaf *l)
 {
         return (u8 *)l->items;
@@ -1031,28 +956,6 @@ static inline void btrfs_set_file_extent_num_blocks(struct
         e->num_blocks = cpu_to_le64(val);
 }
 
-static inline u16 btrfs_device_pathlen(struct btrfs_device_item *d)
-{
-        return le16_to_cpu(d->pathlen);
-}
-
-static inline void btrfs_set_device_pathlen(struct btrfs_device_item *d,
-                                                u16 val)
-{
-        d->pathlen = cpu_to_le16(val);
-}
-
-static inline u64 btrfs_device_id(struct btrfs_device_item *d)
-{
-        return le64_to_cpu(d->device_id);
-}
-
-static inline void btrfs_set_device_id(struct btrfs_device_item *d,
-                                                u64 val)
-{
-        d->device_id = cpu_to_le64(val);
-}
-
 static inline struct btrfs_root *btrfs_sb(struct super_block *sb)
 {
         return sb->s_fs_info;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 751069c0e9f5..8a88404525e8 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -11,47 +11,9 @@
 #include "transaction.h"
 #include "btrfs_inode.h"
 
-struct dev_lookup {
-        u64 block_start;
-        u64 num_blocks;
-        u64 device_id;
-        struct block_device *bdev;
-};
-
-int btrfs_insert_dev_radix(struct btrfs_root *root,
-                           struct block_device *bdev,
-                           u64 device_id,
-                           u64 block_start,
-                           u64 num_blocks)
-{
-        struct dev_lookup *lookup;
-        int ret;
-
-        lookup = kmalloc(sizeof(*lookup), GFP_NOFS);
-        if (!lookup)
-                return -ENOMEM;
-        lookup->block_start = block_start;
-        lookup->num_blocks = num_blocks;
-        lookup->bdev = bdev;
-        lookup->device_id = device_id;
-
-        ret = radix_tree_insert(&root->fs_info->dev_radix, block_start +
-                                num_blocks - 1, lookup);
-        return ret;
-}
-
 u64 bh_blocknr(struct buffer_head *bh)
 {
-        int blkbits = bh->b_page->mapping->host->i_blkbits;
-        u64 blocknr = bh->b_page->index << (PAGE_CACHE_SHIFT - blkbits);
-        unsigned long offset;
-
-        if (PageHighMem(bh->b_page))
-                offset = (unsigned long)bh->b_data;
-        else
-                offset = bh->b_data - (char *)page_address(bh->b_page);
-        blocknr += offset >> (PAGE_CACHE_SHIFT - blkbits);
-        return blocknr;
+        return bh->b_blocknr;
 }
 
 static int check_tree_block(struct btrfs_root *root, struct buffer_head *buf)
@@ -102,32 +64,14 @@ out_unlock:
 int btrfs_map_bh_to_logical(struct btrfs_root *root, struct buffer_head *bh,
                              u64 logical)
 {
-        struct dev_lookup *lookup[2];
-
-        int ret;
-
         if (logical == 0) {
                 bh->b_bdev = NULL;
                 bh->b_blocknr = 0;
                 set_buffer_mapped(bh);
-                return 0;
-        }
-        root = root->fs_info->dev_root;
-        ret = radix_tree_gang_lookup(&root->fs_info->dev_radix,
-                                     (void **)lookup,
-                                     (unsigned long)logical,
-                                     ARRAY_SIZE(lookup));
-        if (ret == 0 || lookup[0]->block_start > logical ||
-            lookup[0]->block_start + lookup[0]->num_blocks <= logical) {
-                ret = -ENOENT;
-                goto out;
+        } else {
+                map_bh(bh, root->fs_info->sb, logical);
         }
-        bh->b_bdev = lookup[0]->bdev;
-        bh->b_blocknr = logical - lookup[0]->block_start;
-        set_buffer_mapped(bh);
-        ret = 0;
-out:
-        return ret;
+        return 0;
 }
 
 struct buffer_head *btrfs_find_create_tree_block(struct btrfs_root *root,
@@ -382,24 +326,18 @@ struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
         u64 highest_inode;
         int ret = 0;
 
-printk("read_fs_root looking for %Lu %Lu %u\n", location->objectid, location->offset, location->flags);
         root = radix_tree_lookup(&fs_info->fs_roots_radix,
                                  (unsigned long)location->objectid);
-        if (root) {
-printk("found %p in cache\n", root);
+        if (root)
                 return root;
-        }
         root = kmalloc(sizeof(*root), GFP_NOFS);
-        if (!root) {
-printk("failed1\n");
+        if (!root)
                 return ERR_PTR(-ENOMEM);
-        }
         if (location->offset == (u64)-1) {
                 ret = find_and_setup_root(fs_info->sb->s_blocksize,
                                           fs_info->tree_root, fs_info,
                                           location->objectid, root);
                 if (ret) {
-printk("failed2\n");
                         kfree(root);
                         return ERR_PTR(ret);
                 }
@@ -413,7 +351,6 @@ printk("failed2\n");
         BUG_ON(!path);
         ret = btrfs_search_slot(NULL, tree_root, location, path, 0, 0);
         if (ret != 0) {
-printk("internal search_slot gives us %d\n", ret);
                 if (ret > 0)
                         ret = -ENOENT;
                 goto out;
@@ -435,13 +372,11 @@ out:
                                      btrfs_root_blocknr(&root->root_item));
         BUG_ON(!root->node);
 insert:
-printk("inserting %p\n", root);
         root->ref_cows = 1;
         ret = radix_tree_insert(&fs_info->fs_roots_radix,
                                 (unsigned long)root->root_key.objectid,
                                 root);
         if (ret) {
-printk("radix_tree_insert gives us %d\n", ret);
                 brelse(root->node);
                 kfree(root);
                 return ERR_PTR(ret);
@@ -450,116 +385,25 @@ printk("radix_tree_insert gives us %d\n", ret);
         if (ret == 0) {
                 root->highest_inode = highest_inode;
                 root->last_inode_alloc = highest_inode;
-printk("highest inode is %Lu\n", highest_inode);
         }
-printk("all worked\n");
         return root;
 }
 
-static int btrfs_open_disk(struct btrfs_root *root, u64 device_id,
-                           u64 block_start, u64 num_blocks,
-                           char *filename, int name_len)
-{
-        char *null_filename;
-        struct block_device *bdev;
-        int ret;
-
-        null_filename = kmalloc(name_len + 1, GFP_NOFS);
-        if (!null_filename)
-                return -ENOMEM;
-        memcpy(null_filename, filename, name_len);
-        null_filename[name_len] = '\0';
-
-        bdev = open_bdev_excl(null_filename, O_RDWR, root->fs_info->sb);
-        if (IS_ERR(bdev)) {
-                ret = PTR_ERR(bdev);
-                goto out;
-        }
-        set_blocksize(bdev, root->fs_info->sb->s_blocksize);
-        ret = btrfs_insert_dev_radix(root, bdev, device_id,
-                                     block_start, num_blocks);
-        BUG_ON(ret);
-        ret = 0;
-out:
-        kfree(null_filename);
-        return ret;
-}
-
-static int read_device_info(struct btrfs_root *root)
-{
-        struct btrfs_path *path;
-        int ret;
-        struct btrfs_key key;
-        struct btrfs_leaf *leaf;
-        struct btrfs_device_item *dev_item;
-        int nritems;
-        int slot;
-
-        root = root->fs_info->dev_root;
-
-        path = btrfs_alloc_path();
-        if (!path)
-                return -ENOMEM;
-        key.objectid = 0;
-        key.offset = 0;
-        key.flags = 0;
-        btrfs_set_key_type(&key, BTRFS_DEV_ITEM_KEY);
-
-        mutex_lock(&root->fs_info->fs_mutex);
-        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
-        leaf = btrfs_buffer_leaf(path->nodes[0]);
-        nritems = btrfs_header_nritems(&leaf->header);
-        while(1) {
-                slot = path->slots[0];
-                if (slot >= nritems) {
-                        ret = btrfs_next_leaf(root, path);
-                        if (ret)
-                                break;
-                        leaf = btrfs_buffer_leaf(path->nodes[0]);
-                        nritems = btrfs_header_nritems(&leaf->header);
-                        slot = path->slots[0];
-                }
-                btrfs_disk_key_to_cpu(&key, &leaf->items[slot].key);
-                if (btrfs_key_type(&key) != BTRFS_DEV_ITEM_KEY) {
-                        path->slots[0]++;
-                        continue;
-                }
-                dev_item = btrfs_item_ptr(leaf, slot, struct btrfs_device_item);
-printk("found key %Lu %Lu\n", key.objectid, key.offset);
-                if (btrfs_device_id(dev_item) !=
-                    btrfs_super_device_id(root->fs_info->disk_super)) {
-                        ret = btrfs_open_disk(root, btrfs_device_id(dev_item),
-                                              key.objectid, key.offset,
-                                              (char *)(dev_item + 1),
-                                              btrfs_device_pathlen(dev_item));
-                        BUG_ON(ret);
-                }
-                path->slots[0]++;
-        }
-        btrfs_free_path(path);
-        mutex_unlock(&root->fs_info->fs_mutex);
-        return 0;
-}
-
 struct btrfs_root *open_ctree(struct super_block *sb)
 {
         struct btrfs_root *extent_root = kmalloc(sizeof(struct btrfs_root),
                                                  GFP_NOFS);
-        struct btrfs_root *dev_root = kmalloc(sizeof(struct btrfs_root),
-                                                 GFP_NOFS);
         struct btrfs_root *tree_root = kmalloc(sizeof(struct btrfs_root),
                                                GFP_NOFS);
         struct btrfs_fs_info *fs_info = kmalloc(sizeof(*fs_info),
                                                 GFP_NOFS);
         int ret;
         struct btrfs_super_block *disk_super;
-        struct dev_lookup *dev_lookup;
 
         init_bit_radix(&fs_info->pinned_radix);
         init_bit_radix(&fs_info->pending_del_radix);
         init_bit_radix(&fs_info->extent_map_radix);
         INIT_RADIX_TREE(&fs_info->fs_roots_radix, GFP_NOFS);
-        INIT_RADIX_TREE(&fs_info->dev_radix, GFP_NOFS);
         INIT_RADIX_TREE(&fs_info->block_group_radix, GFP_KERNEL);
         INIT_RADIX_TREE(&fs_info->block_group_data_radix, GFP_KERNEL);
         INIT_LIST_HEAD(&fs_info->trans_list);
@@ -568,7 +412,6 @@ struct btrfs_root *open_ctree(struct super_block *sb)
         fs_info->running_transaction = NULL;
         fs_info->tree_root = tree_root;
         fs_info->extent_root = extent_root;
-        fs_info->dev_root = dev_root;
         fs_info->sb = sb;
         fs_info->btree_inode = new_inode(sb);
         fs_info->btree_inode->i_ino = 1;
@@ -595,19 +438,9 @@ struct btrfs_root *open_ctree(struct super_block *sb)
         mutex_init(&fs_info->trans_mutex);
         mutex_init(&fs_info->fs_mutex);
 
-        __setup_root(sb->s_blocksize, dev_root,
-                     fs_info, BTRFS_DEV_TREE_OBJECTID);
-
         __setup_root(sb->s_blocksize, tree_root,
                      fs_info, BTRFS_ROOT_TREE_OBJECTID);
 
-        dev_lookup = kmalloc(sizeof(*dev_lookup), GFP_NOFS);
-        dev_lookup->block_start = 0;
-        dev_lookup->num_blocks = (u32)-2;
-        dev_lookup->bdev = sb->s_bdev;
-        dev_lookup->device_id = 0;
-        ret = radix_tree_insert(&fs_info->dev_radix, (u32)-2, dev_lookup);
-        BUG_ON(ret);
         fs_info->sb_buffer = read_tree_block(tree_root,
                                              BTRFS_SUPER_INFO_OFFSET /
                                              sb->s_blocksize);
@@ -622,24 +455,7 @@ struct btrfs_root *open_ctree(struct super_block *sb)
                      btrfs_super_total_blocks(disk_super) <<
                      fs_info->btree_inode->i_blkbits);
 
-        radix_tree_delete(&fs_info->dev_radix, (u32)-2);
-        dev_lookup->block_start = btrfs_super_device_block_start(disk_super);
-        dev_lookup->num_blocks = btrfs_super_device_num_blocks(disk_super);
-        dev_lookup->device_id = btrfs_super_device_id(disk_super);
-
-        ret = radix_tree_insert(&fs_info->dev_radix,
-                                dev_lookup->block_start +
-                                dev_lookup->num_blocks - 1, dev_lookup);
-        BUG_ON(ret);
-
         fs_info->disk_super = disk_super;
-
-        dev_root->node = read_tree_block(tree_root,
-                                          btrfs_super_device_root(disk_super));
-
-        ret = read_device_info(dev_root);
-        BUG_ON(ret);
-
         tree_root->node = read_tree_block(tree_root,
                                           btrfs_super_root(disk_super));
         BUG_ON(!tree_root->node);
@@ -719,30 +535,6 @@ static int del_fs_roots(struct btrfs_fs_info *fs_info)
         return 0;
 }
 
-static int free_dev_radix(struct btrfs_fs_info *fs_info)
-{
-        struct dev_lookup *lookup[8];
-        struct block_device *super_bdev = fs_info->sb->s_bdev;
-        int ret;
-        int i;
-        while(1) {
-                ret = radix_tree_gang_lookup(&fs_info->dev_radix,
-                                             (void **)lookup, 0,
-                                             ARRAY_SIZE(lookup));
-                if (!ret)
-                        break;
-                for (i = 0; i < ret; i++) {
-                        if (lookup[i]->bdev != super_bdev)
-                                close_bdev_excl(lookup[i]->bdev);
-                        radix_tree_delete(&fs_info->dev_radix,
-                                          lookup[i]->block_start +
-                                          lookup[i]->num_blocks - 1);
-                        kfree(lookup[i]);
-                }
-        }
-        return 0;
-}
-
 int close_ctree(struct btrfs_root *root)
 {
         int ret;
@@ -765,9 +557,6 @@ int close_ctree(struct btrfs_root *root)
         if (fs_info->extent_root->node)
                 btrfs_block_release(fs_info->extent_root,
                                     fs_info->extent_root->node);
-        if (fs_info->dev_root->node)
-                btrfs_block_release(fs_info->dev_root,
-                                    fs_info->dev_root->node);
         if (fs_info->tree_root->node)
                 btrfs_block_release(fs_info->tree_root,
                                     fs_info->tree_root->node);
@@ -776,7 +565,6 @@ int close_ctree(struct btrfs_root *root)
         truncate_inode_pages(fs_info->btree_inode->i_mapping, 0);
         iput(fs_info->btree_inode);
 
-        free_dev_radix(fs_info);
         btrfs_free_block_groups(root->fs_info);
         del_fs_roots(fs_info);
         kfree(fs_info->extent_root);
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 5864917953a4..2b24a5a2be63 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2566,83 +2566,6 @@ static int create_snapshot(struct btrfs_root *root, char *name, int namelen)
         return 0;
 }
 
-static int add_disk(struct btrfs_root *root, char *name, int namelen)
-{
-        struct block_device *bdev;
-        struct btrfs_path *path;
-        struct super_block *sb = root->fs_info->sb;
-        struct btrfs_root *dev_root = root->fs_info->dev_root;
-        struct btrfs_trans_handle *trans;
-        struct btrfs_device_item *dev_item;
-        struct btrfs_key key;
-        u16 item_size;
-        u64 num_blocks;
-        u64 new_blocks;
-        u64 device_id;
-        int ret;
-
-printk("adding disk %s\n", name);
-        path = btrfs_alloc_path();
-        if (!path)
-                return -ENOMEM;
-        num_blocks = btrfs_super_total_blocks(root->fs_info->disk_super);
-        bdev = open_bdev_excl(name, O_RDWR, sb);
-        if (IS_ERR(bdev)) {
-                ret = PTR_ERR(bdev);
-printk("open bdev excl failed ret %d\n", ret);
-                goto out_nolock;
-        }
-        set_blocksize(bdev, sb->s_blocksize);
-        new_blocks = bdev->bd_inode->i_size >> sb->s_blocksize_bits;
-        key.objectid = num_blocks;
-        key.offset = new_blocks;
-        key.flags = 0;
-        btrfs_set_key_type(&key, BTRFS_DEV_ITEM_KEY);
-
-        mutex_lock(&dev_root->fs_info->fs_mutex);
-        trans = btrfs_start_transaction(dev_root, 1);
-        item_size = sizeof(*dev_item) + namelen;
-printk("insert empty on %Lu %Lu %u size %d\n", num_blocks, new_blocks, key.flags, item_size);
-        ret = btrfs_insert_empty_item(trans, dev_root, path, &key, item_size);
-        if (ret) {
-printk("insert failed %d\n", ret);
-                close_bdev_excl(bdev);
-                if (ret > 0)
-                        ret = -EEXIST;
-                goto out;
-        }
-        dev_item = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]),
-                                  path->slots[0], struct btrfs_device_item);
-        btrfs_set_device_pathlen(dev_item, namelen);
-        memcpy(dev_item + 1, name, namelen);
-
-        device_id = btrfs_super_last_device_id(root->fs_info->disk_super) + 1;
-        btrfs_set_super_last_device_id(root->fs_info->disk_super, device_id);
-        btrfs_set_device_id(dev_item, device_id);
-        mark_buffer_dirty(path->nodes[0]);
-
-        ret = btrfs_insert_dev_radix(root, bdev, device_id, num_blocks,
-                                     new_blocks);
-
-        if (!ret) {
-                btrfs_set_super_total_blocks(root->fs_info->disk_super,
-                                             num_blocks + new_blocks);
-                i_size_write(root->fs_info->btree_inode,
-                             (num_blocks + new_blocks) <<
-                             root->fs_info->btree_inode->i_blkbits);
-        }
-
-out:
-        ret = btrfs_commit_transaction(trans, dev_root);
-        BUG_ON(ret);
-        mutex_unlock(&root->fs_info->fs_mutex);
-out_nolock:
-        btrfs_free_path(path);
-        btrfs_btree_balance_dirty(root);
-
-        return ret;
-}
-
 static int btrfs_ioctl(struct inode *inode, struct file *filp, unsigned int
                        cmd, unsigned long arg)
 {
@@ -2682,17 +2605,6 @@ static int btrfs_ioctl(struct inode *inode, struct file *filp, unsigned int
                         ret = create_snapshot(root, vol_args.name, namelen);
                 WARN_ON(ret);
                 break;
-        case BTRFS_IOC_ADD_DISK:
-                if (copy_from_user(&vol_args,
-                                   (struct btrfs_ioctl_vol_args __user *)arg,
-                                   sizeof(vol_args)))
-                        return -EFAULT;
-                namelen = strlen(vol_args.name);
-                if (namelen > BTRFS_VOL_NAME_MAX)
-                        return -EINVAL;
-                vol_args.name[namelen] = '\0';
-                ret = add_disk(root, vol_args.name, namelen);
-                break;
         default:
                 return -ENOTTY;
         }
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index a2c5820f1d3d..4f3c8ddcb401 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -150,13 +150,7 @@ int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
         struct btrfs_fs_info *fs_info = root->fs_info;
         struct btrfs_root *tree_root = fs_info->tree_root;
         struct btrfs_root *extent_root = fs_info->extent_root;
-        struct btrfs_root *dev_root = fs_info->dev_root;
 
-        if (btrfs_super_device_root(fs_info->disk_super) !=
-            bh_blocknr(dev_root->node)) {
-                btrfs_set_super_device_root(fs_info->disk_super,
-                                            bh_blocknr(dev_root->node));
-        }
         btrfs_write_dirty_block_groups(trans, extent_root);
         while(1) {
                 old_extent_block = btrfs_root_blocknr(&extent_root->root_item);