Btrfs: Add support for mirroring across drives
authorChris Mason <chris.mason@oracle.com>
Thu, 3 Apr 2008 20:29:03 +0000 (16:29 -0400)
committerChris Mason <chris.mason@oracle.com>
Thu, 25 Sep 2008 15:04:01 +0000 (11:04 -0400)
Signed-off-by: Chris Mason <chris.mason@oracle.com>
fs/btrfs/ctree.h
fs/btrfs/disk-io.c
fs/btrfs/extent-tree.c
fs/btrfs/inode.c
fs/btrfs/volumes.c
fs/btrfs/volumes.h

index 67d533cf8f47385f2d36f016f8525e3fa6bfb2a6..0a207861472ef4541c6c5740be4d3b2f2d5325f4 100644 (file)
@@ -418,6 +418,7 @@ struct btrfs_csum_item {
 #define BTRFS_BLOCK_GROUP_SYSTEM   (1 << 1)
 #define BTRFS_BLOCK_GROUP_METADATA (1 << 2)
 #define BTRFS_BLOCK_GROUP_RAID0    (1 << 3)
+#define BTRFS_BLOCK_GROUP_RAID1    (1 << 4)
 
 
 struct btrfs_block_group_item {
@@ -504,8 +505,12 @@ struct btrfs_fs_info {
        u64 delalloc_bytes;
        u64 last_alloc;
        u64 last_data_alloc;
-       int extra_data_alloc_bits;
-       int extra_alloc_bits;
+       int avail_data_alloc_bits;
+       int avail_metadata_alloc_bits;
+       int avail_system_alloc_bits;
+       int data_alloc_profile;
+       int metadata_alloc_profile;
+       int system_alloc_profile;
 };
 
 /*
index e40fb318ad99e16d10393e5fb6af601708b836fb..ff75ad586767cbea878566f4c448440c5fe6c4a8 100644 (file)
@@ -735,7 +735,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
                                                 GFP_NOFS);
        struct btrfs_root *tree_root = kmalloc(sizeof(struct btrfs_root),
                                               GFP_NOFS);
-       struct btrfs_fs_info *fs_info = kmalloc(sizeof(*fs_info),
+       struct btrfs_fs_info *fs_info = kzalloc(sizeof(*fs_info),
                                                GFP_NOFS);
        struct btrfs_root *chunk_root = kmalloc(sizeof(struct btrfs_root),
                                                GFP_NOFS);
@@ -744,6 +744,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
        int ret;
        int err = -EINVAL;
        struct btrfs_super_block *disk_super;
+
        if (!extent_root || !tree_root || !fs_info) {
                err = -ENOMEM;
                goto fail;
@@ -756,11 +757,8 @@ struct btrfs_root *open_ctree(struct super_block *sb,
        spin_lock_init(&fs_info->delalloc_lock);
        spin_lock_init(&fs_info->new_trans_lock);
 
-       memset(&fs_info->super_kobj, 0, sizeof(fs_info->super_kobj));
        init_completion(&fs_info->kobj_unregister);
        sb_set_blocksize(sb, 4096);
-       fs_info->running_transaction = NULL;
-       fs_info->last_trans_committed = 0;
        fs_info->tree_root = tree_root;
        fs_info->extent_root = extent_root;
        fs_info->chunk_root = chunk_root;
@@ -770,11 +768,8 @@ struct btrfs_root *open_ctree(struct super_block *sb,
        INIT_LIST_HEAD(&fs_info->space_info);
        btrfs_mapping_init(&fs_info->mapping_tree);
        fs_info->sb = sb;
-       fs_info->throttles = 0;
-       fs_info->mount_opt = 0;
        fs_info->max_extent = (u64)-1;
        fs_info->max_inline = 8192 * 1024;
-       fs_info->delalloc_bytes = 0;
        setup_bdi(fs_info, &fs_info->bdi);
        fs_info->btree_inode = new_inode(sb);
        fs_info->btree_inode->i_ino = 1;
@@ -802,12 +797,6 @@ struct btrfs_root *open_ctree(struct super_block *sb,
        extent_io_tree_init(&fs_info->extent_ins,
                             fs_info->btree_inode->i_mapping, GFP_NOFS);
        fs_info->do_barriers = 1;
-       fs_info->closing = 0;
-       fs_info->total_pinned = 0;
-       fs_info->last_alloc = 0;
-       fs_info->last_data_alloc = 0;
-       fs_info->extra_alloc_bits = 0;
-       fs_info->extra_data_alloc_bits = 0;
 
 #if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)
        INIT_WORK(&fs_info->trans_work, btrfs_transaction_cleaner, fs_info);
@@ -923,6 +912,11 @@ struct btrfs_root *open_ctree(struct super_block *sb,
        btrfs_read_block_groups(extent_root);
 
        fs_info->generation = btrfs_super_generation(disk_super) + 1;
+       if (btrfs_super_num_devices(disk_super) > 0) {
+               fs_info->data_alloc_profile = BTRFS_BLOCK_GROUP_RAID0;
+               fs_info->metadata_alloc_profile = BTRFS_BLOCK_GROUP_RAID1;
+               fs_info->system_alloc_profile = BTRFS_BLOCK_GROUP_RAID0;
+       }
        mutex_unlock(&fs_info->fs_mutex);
        return tree_root;
 
index a34c289aec2132faae8296b98232befe737e1ab0..4ab98d8b73fa09addf376765bd98d779e896f117 100644 (file)
@@ -230,9 +230,13 @@ again:
                        goto new_group;
                if (start + num  > total_fs_bytes)
                        goto new_group;
+               if (!block_group_bits(cache, data)) {
+                       printk("block group bits don't match %Lu %Lu\n", cache->flags, data);
+               }
                *start_ret = start;
                return 0;
-       } out:
+       }
+out:
        cache = btrfs_lookup_block_group(root->fs_info, search_start);
        if (!cache) {
                printk("Unable to find block group for %Lu\n", search_start);
@@ -365,14 +369,17 @@ again:
                if (cache->key.objectid > total_fs_bytes)
                        break;
 
-               if (full_search)
-                       free_check = cache->key.offset;
-               else
-                       free_check = div_factor(cache->key.offset, factor);
+               if (block_group_bits(cache, data)) {
+                       if (full_search)
+                               free_check = cache->key.offset;
+                       else
+                               free_check = div_factor(cache->key.offset,
+                                                       factor);
 
-               if (used + cache->pinned < free_check) {
-                       found_group = cache;
-                       goto found;
+                       if (used + cache->pinned < free_check) {
+                               found_group = cache;
+                               goto found;
+                       }
                }
                cond_resched();
        }
@@ -1038,6 +1045,19 @@ static int update_space_info(struct btrfs_fs_info *info, u64 flags,
        return 0;
 }
 
+static void set_avail_alloc_bits(struct btrfs_fs_info *fs_info, u64 flags)
+{
+       u64 extra_flags = flags & (BTRFS_BLOCK_GROUP_RAID0 |
+                                  BTRFS_BLOCK_GROUP_RAID1);
+       if (extra_flags) {
+               if (flags & BTRFS_BLOCK_GROUP_DATA)
+                       fs_info->avail_data_alloc_bits |= extra_flags;
+               if (flags & BTRFS_BLOCK_GROUP_METADATA)
+                       fs_info->avail_metadata_alloc_bits |= extra_flags;
+               if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
+                       fs_info->avail_system_alloc_bits |= extra_flags;
+       }
+}
 
 static int do_chunk_alloc(struct btrfs_trans_handle *trans,
                          struct btrfs_root *extent_root, u64 alloc_bytes,
@@ -1060,7 +1080,7 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans,
        if (space_info->full)
                return 0;
 
-       thresh = div_factor(space_info->total_bytes, 7);
+       thresh = div_factor(space_info->total_bytes, 6);
        if ((space_info->bytes_used + space_info->bytes_pinned + alloc_bytes) <
            thresh)
                return 0;
@@ -1079,16 +1099,7 @@ printk("space info full %Lu\n", flags);
                     start, num_bytes);
        BUG_ON(ret);
 
-       if (flags & BTRFS_BLOCK_GROUP_RAID0) {
-               if (flags & BTRFS_BLOCK_GROUP_DATA) {
-                       extent_root->fs_info->extra_data_alloc_bits =
-                               BTRFS_BLOCK_GROUP_RAID0;
-               }
-               if (flags & BTRFS_BLOCK_GROUP_METADATA) {
-                       extent_root->fs_info->extra_alloc_bits =
-                               BTRFS_BLOCK_GROUP_RAID0;
-               }
-       }
+       set_avail_alloc_bits(extent_root->fs_info, flags);
        return 0;
 }
 
@@ -1529,6 +1540,7 @@ static int noinline find_free_extent(struct btrfs_trans_handle *trans,
 
        if (data & BTRFS_BLOCK_GROUP_METADATA) {
                last_ptr = &root->fs_info->last_alloc;
+               empty_cluster = 256 * 1024;
        }
 
        if ((data & BTRFS_BLOCK_GROUP_DATA) && btrfs_test_opt(root, SSD)) {
@@ -1693,6 +1705,7 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
        u64 root_used;
        u64 search_start = 0;
        u64 new_hint;
+       u64 alloc_profile;
        u32 sizes[2];
        struct btrfs_fs_info *info = root->fs_info;
        struct btrfs_root *extent_root = info->extent_root;
@@ -1700,31 +1713,32 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
        struct btrfs_extent_ref *ref;
        struct btrfs_path *path;
        struct btrfs_key keys[2];
-       int extra_chunk_alloc_bits = 0;
 
        if (data) {
-               data = BTRFS_BLOCK_GROUP_DATA | info->extra_data_alloc_bits;
+               alloc_profile = info->avail_data_alloc_bits &
+                               info->data_alloc_profile;
+               data = BTRFS_BLOCK_GROUP_DATA | alloc_profile;
        } else if (root == root->fs_info->chunk_root) {
-               data = BTRFS_BLOCK_GROUP_SYSTEM;
+               alloc_profile = info->avail_system_alloc_bits &
+                               info->system_alloc_profile;
+               data = BTRFS_BLOCK_GROUP_SYSTEM | alloc_profile;
        } else {
-               data = BTRFS_BLOCK_GROUP_METADATA | info->extra_alloc_bits;
+               alloc_profile = info->avail_metadata_alloc_bits &
+                               info->metadata_alloc_profile;
+               data = BTRFS_BLOCK_GROUP_METADATA | alloc_profile;
        }
-       if (btrfs_super_num_devices(&info->super_copy) > 1 &&
-           !(data & BTRFS_BLOCK_GROUP_SYSTEM))
-               extra_chunk_alloc_bits = BTRFS_BLOCK_GROUP_RAID0;
 
        if (root->ref_cows) {
                if (!(data & BTRFS_BLOCK_GROUP_METADATA)) {
                        ret = do_chunk_alloc(trans, root->fs_info->extent_root,
                                             2 * 1024 * 1024,
                                             BTRFS_BLOCK_GROUP_METADATA |
-                                            info->extra_alloc_bits |
-                                            extra_chunk_alloc_bits);
+                                            (info->metadata_alloc_profile &
+                                             info->avail_metadata_alloc_bits));
                        BUG_ON(ret);
                }
                ret = do_chunk_alloc(trans, root->fs_info->extent_root,
-                                    num_bytes + 2 * 1024 * 1024, data |
-                                    extra_chunk_alloc_bits);
+                                    num_bytes + 2 * 1024 * 1024, data);
                BUG_ON(ret);
        }
 
@@ -2046,12 +2060,12 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
                if (!next || !btrfs_buffer_uptodate(next)) {
                        free_extent_buffer(next);
                        reada_walk_down(root, cur, path->slots[*level]);
+
+                       mutex_unlock(&root->fs_info->fs_mutex);
                        next = read_tree_block(root, bytenr, blocksize);
+                       mutex_lock(&root->fs_info->fs_mutex);
 
-                       /* we used to drop the lock above, keep the
-                        * code to double check so that we won't forget
-                        * when we drop the lock again in the future
-                        */
+                       /* we've dropped the lock, double check */
                        ret = lookup_extent_ref(trans, root, bytenr,
                                                blocksize, &refs);
                        BUG_ON(ret);
@@ -2739,16 +2753,7 @@ int btrfs_read_block_groups(struct btrfs_root *root)
                } else if (cache->flags & BTRFS_BLOCK_GROUP_METADATA) {
                        bit = BLOCK_GROUP_METADATA;
                }
-               if (cache->flags & BTRFS_BLOCK_GROUP_RAID0) {
-                       if (cache->flags & BTRFS_BLOCK_GROUP_DATA) {
-                               info->extra_data_alloc_bits =
-                                       BTRFS_BLOCK_GROUP_RAID0;
-                       }
-                       if (cache->flags & BTRFS_BLOCK_GROUP_METADATA) {
-                               info->extra_alloc_bits =
-                                       BTRFS_BLOCK_GROUP_RAID0;
-                       }
-               }
+               set_avail_alloc_bits(info, cache->flags);
 
                ret = update_space_info(info, cache->flags, found_key.offset,
                                        btrfs_block_group_used(&cache->item),
index 0fa7cf227f1a5a023c0e47f299e57d9b41fe13bb..a8ae68c6fbb844f61d5cc42150f13993d032cc49 100644 (file)
@@ -306,6 +306,7 @@ int btrfs_merge_bio_hook(struct page *page, unsigned long offset,
        u64 physical;
        u64 length = 0;
        u64 map_length;
+       int total_devs;
        struct bio_vec *bvec;
        int i;
        int ret;
@@ -315,7 +316,8 @@ int btrfs_merge_bio_hook(struct page *page, unsigned long offset,
        }
        map_tree = &root->fs_info->mapping_tree;
        map_length = length;
-       ret = btrfs_map_block(map_tree, logical, &physical, &map_length, &dev);
+       ret = btrfs_map_block(map_tree, READ, 0, logical, &physical,
+                             &map_length, &dev, &total_devs);
        if (map_length < length + size) {
                return 1;
        }
index 169be0f7285b56331065dd0ef09341de4d95eec4..bc3c0b97588ead16b257bb5ee88bfe7b873a1966 100644 (file)
@@ -31,6 +31,13 @@ struct stripe {
        u64 physical;
 };
 
+struct multi_bio {
+       atomic_t stripes;
+       bio_end_io_t *end_io;
+       void *private;
+       int error;
+};
+
 struct map_lookup {
        u64 type;
        int io_align;
@@ -632,12 +639,12 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
        if (list_empty(dev_list))
                return -ENOSPC;
 
-       if (type & BTRFS_BLOCK_GROUP_RAID0)
+       if (type & (BTRFS_BLOCK_GROUP_RAID0))
                num_stripes = btrfs_super_num_devices(&info->super_copy);
-       if (type & BTRFS_BLOCK_GROUP_DATA)
-               stripe_len = 64 * 1024;
-       if (type & (BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_SYSTEM))
-               stripe_len = 32 * 1024;
+       if (type & (BTRFS_BLOCK_GROUP_RAID1)) {
+               num_stripes = min_t(u64, 2,
+                                 btrfs_super_num_devices(&info->super_copy));
+       }
 again:
        INIT_LIST_HEAD(&private_devs);
        cur = dev_list->next;
@@ -682,7 +689,11 @@ again:
 
        stripes = &chunk->stripe;
 
-       *num_bytes = calc_size * num_stripes;
+       if (type & BTRFS_BLOCK_GROUP_RAID1)
+               *num_bytes = calc_size;
+       else
+               *num_bytes = calc_size * num_stripes;
+
        index = 0;
        while(index < num_stripes) {
                BUG_ON(list_empty(&private_devs));
@@ -694,7 +705,7 @@ again:
                                             key.objectid,
                                             calc_size, &dev_offset);
                BUG_ON(ret);
-printk("alloc chunk size %Lu from dev %Lu\n", calc_size, device->devid);
+printk("alloc chunk start %Lu size %Lu from dev %Lu type %Lu\n", key.objectid, calc_size, device->devid, type);
                device->bytes_used += calc_size;
                ret = btrfs_update_device(trans, device);
                BUG_ON(ret);
@@ -774,9 +785,9 @@ void btrfs_mapping_tree_free(struct btrfs_mapping_tree *tree)
        }
 }
 
-int btrfs_map_block(struct btrfs_mapping_tree *map_tree,
-                   u64 logical, u64 *phys, u64 *length,
-                   struct btrfs_device **dev)
+int btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
+                   int dev_nr, u64 logical, u64 *phys, u64 *length,
+                   struct btrfs_device **dev, int *total_devs)
 {
        struct extent_map *em;
        struct map_lookup *map;
@@ -808,19 +819,39 @@ int btrfs_map_block(struct btrfs_mapping_tree *map_tree,
        /* stripe_offset is the offset of this block in its stripe*/
        stripe_offset = offset - stripe_offset;
 
-       /*
-        * 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 = do_div(stripe_nr, map->num_stripes);
-
+       if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
+               stripe_index = dev_nr;
+               if (rw & (1 << BIO_RW))
+                       *total_devs = map->num_stripes;
+               else {
+                       int i;
+                       u64 least = (u64)-1;
+                       struct btrfs_device *cur;
+
+                       for (i = 0; i < map->num_stripes; i++) {
+                               cur = map->stripes[i].dev;
+                               spin_lock(&cur->io_lock);
+                               if (cur->total_ios < least) {
+                                       least = cur->total_ios;
+                                       stripe_index = i;
+                               }
+                               spin_unlock(&cur->io_lock);
+                       }
+                       *total_devs = 1;
+               }
+       } 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 = do_div(stripe_nr, map->num_stripes);
+       }
        BUG_ON(stripe_index >= map->num_stripes);
-
        *phys = map->stripes[stripe_index].physical + stripe_offset +
                stripe_nr * map->stripe_len;
 
-       if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
+       if (map->type & (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1)) {
                /* we limit the length of each bio to what fits in a stripe */
                *length = min_t(u64, em->len - offset,
                              map->stripe_len - stripe_offset);
@@ -833,33 +864,98 @@ int btrfs_map_block(struct btrfs_mapping_tree *map_tree,
        return 0;
 }
 
+#if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
+static void end_bio_multi_stripe(struct bio *bio, int err)
+#else
+static int end_bio_multi_stripe(struct bio *bio,
+                                  unsigned int bytes_done, int err)
+#endif
+{
+       struct multi_bio *multi = bio->bi_private;
+
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
+       if (bio->bi_size)
+               return 1;
+#endif
+       if (err)
+               multi->error = err;
+
+       if (atomic_dec_and_test(&multi->stripes)) {
+               bio->bi_private = multi->private;
+               bio->bi_end_io = multi->end_io;
+
+               if (!err && multi->error)
+                       err = multi->error;
+               kfree(multi);
+
+               bio_endio(bio, err);
+       } else {
+               bio_put(bio);
+       }
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
+       return 0;
+#endif
+}
+
 int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio)
 {
        struct btrfs_mapping_tree *map_tree;
        struct btrfs_device *dev;
+       struct bio *first_bio = bio;
        u64 logical = bio->bi_sector << 9;
        u64 physical;
        u64 length = 0;
        u64 map_length;
        struct bio_vec *bvec;
+       struct multi_bio *multi = NULL;
        int i;
        int ret;
+       int dev_nr = 0;
+       int total_devs = 1;
 
        bio_for_each_segment(bvec, bio, i) {
                length += bvec->bv_len;
        }
+
        map_tree = &root->fs_info->mapping_tree;
        map_length = length;
-       ret = btrfs_map_block(map_tree, logical, &physical, &map_length, &dev);
-       if (map_length < length) {
-               printk("mapping failed logical %Lu bio len %Lu physical %Lu "
-                      "len %Lu\n", logical, length, physical, map_length);
-               BUG();
+       while(dev_nr < total_devs) {
+               ret = btrfs_map_block(map_tree, rw, dev_nr, logical,
+                                     &physical, &map_length, &dev,
+                                     &total_devs);
+               if (map_length < length) {
+                       printk("mapping failed logical %Lu bio len %Lu physical %Lu "
+                              "len %Lu\n", logical, length, physical, map_length);
+                       BUG();
+               }
+               BUG_ON(map_length < length);
+               if (total_devs > 1) {
+                       if (!multi) {
+                               multi = kmalloc(sizeof(*multi), GFP_NOFS);
+                               atomic_set(&multi->stripes, 1);
+                               multi->end_io = bio->bi_end_io;
+                               multi->private = first_bio->bi_private;
+                               multi->error = 0;
+                       } else {
+                               atomic_inc(&multi->stripes);
+                       }
+                       if (dev_nr < total_devs - 1) {
+                               bio = bio_clone(first_bio, GFP_NOFS);
+                               BUG_ON(!bio);
+                       } else {
+                               bio = first_bio;
+                       }
+                       bio->bi_private = multi;
+                       bio->bi_end_io = end_bio_multi_stripe;
+               }
+               bio->bi_sector = physical >> 9;
+               bio->bi_bdev = dev->bdev;
+               spin_lock(&dev->io_lock);
+               dev->total_ios++;
+               spin_unlock(&dev->io_lock);
+               submit_bio(rw, bio);
+               dev_nr++;
        }
-       BUG_ON(map_length < length);
-       bio->bi_sector = physical >> 9;
-       bio->bi_bdev = dev->bdev;
-       submit_bio(rw, bio);
        return 0;
 }
 
@@ -982,6 +1078,8 @@ static int read_one_dev(struct btrfs_root *root,
                        return -ENOMEM;
                list_add(&device->dev_list,
                         &root->fs_info->fs_devices->devices);
+               device->total_ios = 0;
+               spin_lock_init(&device->io_lock);
        }
 
        fill_device_from_item(leaf, dev_item, device);
index 12f297eb05597313c2f370cf502d75dffb693102..35dec3efd78cc83d89d413488a398d710c8650a6 100644 (file)
 
 #ifndef __BTRFS_VOLUMES_
 #define __BTRFS_VOLUMES_
+
 struct btrfs_device {
        struct list_head dev_list;
        struct btrfs_root *dev_root;
+       spinlock_t io_lock;
 
        struct block_device *bdev;
 
+       u64 total_ios;
+
        char *name;
 
        /* the internal btrfs device id */
@@ -68,9 +72,9 @@ struct btrfs_fs_devices {
 int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
                           struct btrfs_device *device,
                           u64 owner, u64 num_bytes, u64 *start);
-int btrfs_map_block(struct btrfs_mapping_tree *map_tree,
+int btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw, int stripe_nr,
                    u64 logical, u64 *phys, u64 *length,
-                   struct btrfs_device **dev);
+                   struct btrfs_device **dev, int *total_stripes);
 int btrfs_read_sys_array(struct btrfs_root *root);
 int btrfs_read_chunk_tree(struct btrfs_root *root);
 int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
@@ -80,9 +84,6 @@ void btrfs_mapping_init(struct btrfs_mapping_tree *tree);
 void btrfs_mapping_tree_free(struct btrfs_mapping_tree *tree);
 int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio);
 int btrfs_read_super_device(struct btrfs_root *root, struct extent_buffer *buf);
-int btrfs_map_block(struct btrfs_mapping_tree *map_tree,
-                   u64 logical, u64 *phys, u64 *length,
-                   struct btrfs_device **dev);
 int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
                       int flags, void *holder);
 int btrfs_scan_one_device(const char *path, int flags, void *holder,