Btrfs: Add support for mirroring across drives

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

6 files changed, 198 insertions, 93 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 67d533cf8f47..0a207861472e 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -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;
 };
 
 /*
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index e40fb318ad99..ff75ad586767 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -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;
 
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index a34c289aec21..4ab98d8b73fa 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -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),
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 0fa7cf227f1a..a8ae68c6fbb8 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -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;
         }
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 169be0f7285b..bc3c0b97588e 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -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);
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 12f297eb0559..35dec3efd78c 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -18,12 +18,16 @@
 
 #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,