6 files changed, 509 insertions, 74 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index aaa049b8e134..b82931f97ef3 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -633,11 +633,29 @@ struct btrfs_space_info {
         struct rw_semaphore groups_sem;
 };
 
-struct btrfs_free_space {
-        struct rb_node bytes_index;
-        struct rb_node offset_index;
-        u64 offset;
-        u64 bytes;
+/*
+ * free clusters are used to claim free space in relatively large chunks,
+ * allowing us to do less seeky writes.  They are used for all metadata
+ * allocations and data allocations in ssd mode.
+ */
+struct btrfs_free_cluster {
+        spinlock_t lock;
+        spinlock_t refill_lock;
+        struct rb_root root;
+
+        /* largest extent in this cluster */
+        u64 max_size;
+
+        /* first extent starting offset */
+        u64 window_start;
+
+        struct btrfs_block_group_cache *block_group;
+        /*
+         * when a cluster is allocated from a block group, we put the
+         * cluster onto a list in the block group so that it can
+         * be freed before the block group is freed.
+         */
+        struct list_head block_group_list;
 };
 
 struct btrfs_block_group_cache {
@@ -667,6 +685,11 @@ struct btrfs_block_group_cache {
 
         /* usage count */
         atomic_t count;
+
+        /* List of struct btrfs_free_clusters for this block group.
+         * Today it will only have one thing on it, but that may change
+         */
+        struct list_head cluster_list;
 };
 
 struct btrfs_leaf_ref_tree {
@@ -838,8 +861,12 @@ struct btrfs_fs_info {
         spinlock_t delalloc_lock;
         spinlock_t new_trans_lock;
         u64 delalloc_bytes;
-        u64 last_alloc;
-        u64 last_data_alloc;
+
+        /* data_alloc_cluster is only used in ssd mode */
+        struct btrfs_free_cluster data_alloc_cluster;
+
+        /* all metadata allocations go through this cluster */
+        struct btrfs_free_cluster meta_alloc_cluster;
 
         spinlock_t ref_cache_lock;
         u64 total_ref_cache_size;
@@ -1747,6 +1774,7 @@ static inline struct dentry *fdentry(struct file *file)
 }
 
 /* extent-tree.c */
+void btrfs_put_block_group(struct btrfs_block_group_cache *cache);
 int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
                            struct btrfs_root *root, unsigned long count);
 int btrfs_lookup_extent(struct btrfs_root *root, u64 start, u64 len);
@@ -2173,16 +2201,4 @@ int btrfs_check_acl(struct inode *inode, int mask);
 int btrfs_init_acl(struct inode *inode, struct inode *dir);
 int btrfs_acl_chmod(struct inode *inode);
 
-/* free-space-cache.c */
-int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
-                         u64 bytenr, u64 size);
-int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
-                            u64 bytenr, u64 size);
-void btrfs_remove_free_space_cache(struct btrfs_block_group_cache
-                                   *block_group);
-u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
-                               u64 offset, u64 bytes, u64 empty_size);
-void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
-                           u64 bytes);
-u64 btrfs_block_group_free_space(struct btrfs_block_group_cache *block_group);
 #endif
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index ea59ebfa505d..e68ef7b456b0 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -38,6 +38,7 @@
 #include "locking.h"
 #include "ref-cache.h"
 #include "tree-log.h"
+#include "free-space-cache.h"
 
 static struct extent_io_ops btree_extent_io_ops;
 static void end_workqueue_fn(struct btrfs_work *work);
@@ -1652,6 +1653,10 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         mutex_init(&fs_info->cleaner_mutex);
         mutex_init(&fs_info->volume_mutex);
         mutex_init(&fs_info->tree_reloc_mutex);
+
+        btrfs_init_free_cluster(&fs_info->meta_alloc_cluster);
+        btrfs_init_free_cluster(&fs_info->data_alloc_cluster);
+
         init_waitqueue_head(&fs_info->transaction_throttle);
         init_waitqueue_head(&fs_info->transaction_wait);
         init_waitqueue_head(&fs_info->async_submit_wait);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 15d62a9214b7..178df4c67de4 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -31,6 +31,7 @@
 #include "volumes.h"
 #include "locking.h"
 #include "ref-cache.h"
+#include "free-space-cache.h"
 
 #define PENDING_EXTENT_INSERT 0
 #define PENDING_EXTENT_DELETE 1
@@ -324,7 +325,7 @@ struct btrfs_block_group_cache *btrfs_lookup_block_group(
         return cache;
 }
 
-static inline void put_block_group(struct btrfs_block_group_cache *cache)
+void btrfs_put_block_group(struct btrfs_block_group_cache *cache)
 {
         if (atomic_dec_and_test(&cache->count))
                 kfree(cache);
@@ -397,12 +398,12 @@ again:
                             div_factor(cache->key.offset, factor)) {
                                 group_start = cache->key.objectid;
                                 spin_unlock(&cache->lock);
-                                put_block_group(cache);
+                                btrfs_put_block_group(cache);
                                 goto found;
                         }
                 }
                 spin_unlock(&cache->lock);
-                put_block_group(cache);
+                btrfs_put_block_group(cache);
                 cond_resched();
         }
         if (!wrapped) {
@@ -1592,7 +1593,7 @@ int btrfs_extent_readonly(struct btrfs_root *root, u64 bytenr)
         if (!block_group || block_group->ro)
                 readonly = 1;
         if (block_group)
-                put_block_group(block_group);
+                btrfs_put_block_group(block_group);
         return readonly;
 }
 
@@ -2016,7 +2017,7 @@ static int update_block_group(struct btrfs_trans_handle *trans,
                                 WARN_ON(ret);
                         }
                 }
-                put_block_group(cache);
+                btrfs_put_block_group(cache);
                 total -= num_bytes;
                 bytenr += num_bytes;
         }
@@ -2033,7 +2034,7 @@ static u64 first_logical_byte(struct btrfs_root *root, u64 search_start)
                 return 0;
 
         bytenr = cache->key.objectid;
-        put_block_group(cache);
+        btrfs_put_block_group(cache);
 
         return bytenr;
 }
@@ -2077,7 +2078,7 @@ int btrfs_update_pinned_extents(struct btrfs_root *root,
                         if (cache->cached)
                                 btrfs_add_free_space(cache, bytenr, len);
                 }
-                put_block_group(cache);
+                btrfs_put_block_group(cache);
                 bytenr += len;
                 num -= len;
         }
@@ -2108,7 +2109,7 @@ static int update_reserved_extents(struct btrfs_root *root,
                 }
                 spin_unlock(&cache->lock);
                 spin_unlock(&cache->space_info->lock);
-                put_block_group(cache);
+                btrfs_put_block_group(cache);
                 bytenr += len;
                 num -= len;
         }
@@ -2543,12 +2544,13 @@ static noinline int find_free_extent(struct btrfs_trans_handle *trans,
 {
         int ret = 0;
         struct btrfs_root *root = orig_root->fs_info->extent_root;
-        u64 *last_ptr = NULL;
+        struct btrfs_free_cluster *last_ptr = NULL;
         struct btrfs_block_group_cache *block_group = NULL;
         int empty_cluster = 2 * 1024 * 1024;
         int allowed_chunk_alloc = 0;
-        int using_hint = 0;
         struct btrfs_space_info *space_info;
+        int last_ptr_loop = 0;
+        int loop = 0;
 
         WARN_ON(num_bytes < root->sectorsize);
         btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
@@ -2561,38 +2563,39 @@ static noinline int find_free_extent(struct btrfs_trans_handle *trans,
                 allowed_chunk_alloc = 1;
 
         if (data & BTRFS_BLOCK_GROUP_METADATA) {
-                last_ptr = &root->fs_info->last_alloc;
+                last_ptr = &root->fs_info->meta_alloc_cluster;
                 if (!btrfs_test_opt(root, SSD))
                         empty_cluster = 64 * 1024;
         }
 
-        if ((data & BTRFS_BLOCK_GROUP_DATA) && btrfs_test_opt(root, SSD))
-                last_ptr = &root->fs_info->last_data_alloc;
+        if ((data & BTRFS_BLOCK_GROUP_DATA) && btrfs_test_opt(root, SSD)) {
+                last_ptr = &root->fs_info->data_alloc_cluster;
+        }
 
         if (last_ptr) {
-                if (*last_ptr)
-                        hint_byte = *last_ptr;
-                else
-                        empty_size += empty_cluster;
-        } else {
-                empty_cluster = 0;
+                spin_lock(&last_ptr->lock);
+                if (last_ptr->block_group)
+                        hint_byte = last_ptr->window_start;
+                spin_unlock(&last_ptr->lock);
         }
+
         search_start = max(search_start, first_logical_byte(root, 0));
         search_start = max(search_start, hint_byte);
 
+        if (!last_ptr) {
+                empty_cluster = 0;
+                loop = 1;
+        }
+
         if (search_start == hint_byte) {
-                using_hint = 1;
                 block_group = btrfs_lookup_block_group(root->fs_info,
                                                        search_start);
                 if (block_group && block_group_bits(block_group, data)) {
                         down_read(&space_info->groups_sem);
                         goto have_block_group;
                 } else if (block_group) {
-                        put_block_group(block_group);
+                        btrfs_put_block_group(block_group);
                 }
-
-                empty_size += empty_cluster;
-                using_hint = 0;
         }
 
 search:
@@ -2609,7 +2612,7 @@ have_block_group:
                         ret = cache_block_group(root, block_group);
                         mutex_unlock(&block_group->cache_mutex);
                         if (ret) {
-                                put_block_group(block_group);
+                                btrfs_put_block_group(block_group);
                                 break;
                         }
                 }
@@ -2617,11 +2620,88 @@ have_block_group:
                 if (unlikely(block_group->ro))
                         goto loop;
 
+                if (last_ptr) {
+                        /*
+                         * the refill lock keeps out other
+                         * people trying to start a new cluster
+                         */
+                        spin_lock(&last_ptr->refill_lock);
+                        offset = btrfs_alloc_from_cluster(block_group, last_ptr,
+                                                 num_bytes, search_start);
+                        if (offset) {
+                                /* we have a block, we're done */
+                                spin_unlock(&last_ptr->refill_lock);
+                                goto checks;
+                        }
+
+                        spin_lock(&last_ptr->lock);
+                        /*
+                         * whoops, this cluster doesn't actually point to
+                         * this block group.  Get a ref on the block
+                         * group is does point to and try again
+                         */
+                        if (!last_ptr_loop && last_ptr->block_group &&
+                            last_ptr->block_group != block_group) {
+
+                                btrfs_put_block_group(block_group);
+                                block_group = last_ptr->block_group;
+                                atomic_inc(&block_group->count);
+                                spin_unlock(&last_ptr->lock);
+                                spin_unlock(&last_ptr->refill_lock);
+
+                                last_ptr_loop = 1;
+                                search_start = block_group->key.objectid;
+                                goto have_block_group;
+                        }
+                        spin_unlock(&last_ptr->lock);
+
+                        /*
+                         * this cluster didn't work out, free it and
+                         * start over
+                         */
+                        btrfs_return_cluster_to_free_space(NULL, last_ptr);
+
+                        last_ptr_loop = 0;
+
+                        /* allocate a cluster in this block group */
+                        ret = btrfs_find_space_cluster(trans,
+                                               block_group, last_ptr,
+                                               offset, num_bytes,
+                                               empty_cluster + empty_size);
+                        if (ret == 0) {
+                                /*
+                                 * now pull our allocation out of this
+                                 * cluster
+                                 */
+                                offset = btrfs_alloc_from_cluster(block_group,
+                                                  last_ptr, num_bytes,
+                                                  search_start);
+                                if (offset) {
+                                        /* we found one, proceed */
+                                        spin_unlock(&last_ptr->refill_lock);
+                                        goto checks;
+                                }
+                        }
+                        /*
+                         * at this point we either didn't find a cluster
+                         * or we weren't able to allocate a block from our
+                         * cluster.  Free the cluster we've been trying
+                         * to use, and go to the next block group
+                         */
+                        if (loop < 2) {
+                                btrfs_return_cluster_to_free_space(NULL,
+                                                                   last_ptr);
+                                spin_unlock(&last_ptr->refill_lock);
+                                goto loop;
+                        }
+                        spin_unlock(&last_ptr->refill_lock);
+                }
+
                 offset = btrfs_find_space_for_alloc(block_group, search_start,
                                                     num_bytes, empty_size);
                 if (!offset)
                         goto loop;
-
+checks:
                 search_start = stripe_align(root, offset);
 
                 /* move on to the next group */
@@ -2637,11 +2717,6 @@ have_block_group:
                         goto loop;
                 }
 
-                if (using_hint && search_start > hint_byte) {
-                        btrfs_add_free_space(block_group, offset, num_bytes);
-                        goto loop;
-                }
-
                 if (exclude_nr > 0 &&
                     (search_start + num_bytes > exclude_start &&
                      search_start < exclude_start + exclude_nr)) {
@@ -2670,33 +2745,33 @@ have_block_group:
                 /* we are all good, lets return */
                 break;
 loop:
-                put_block_group(block_group);
-                if (using_hint) {
-                        empty_size += empty_cluster;
-                        using_hint = 0;
-                        up_read(&space_info->groups_sem);
-                        goto search;
-                }
+                btrfs_put_block_group(block_group);
         }
         up_read(&space_info->groups_sem);
 
-        if (!ins->objectid && (empty_size || allowed_chunk_alloc)) {
-                int try_again = empty_size;
-
-                empty_size = 0;
+        /* loop == 0, try to find a clustered alloc in every block group
+         * loop == 1, try again after forcing a chunk allocation
+         * loop == 2, set empty_size and empty_cluster to 0 and try again
+         */
+        if (!ins->objectid && loop < 3 &&
+            (empty_size || empty_cluster || allowed_chunk_alloc)) {
+                if (loop >= 2) {
+                        empty_size = 0;
+                        empty_cluster = 0;
+                }
 
                 if (allowed_chunk_alloc) {
                         ret = do_chunk_alloc(trans, root, num_bytes +
                                              2 * 1024 * 1024, data, 1);
-                        if (!ret)
-                                try_again = 1;
                         allowed_chunk_alloc = 0;
                 } else {
                         space_info->force_alloc = 1;
                 }
 
-                if (try_again)
+                if (loop < 3) {
+                        loop++;
                         goto search;
+                }
                 ret = -ENOSPC;
         } else if (!ins->objectid) {
                 ret = -ENOSPC;
@@ -2707,9 +2782,7 @@ loop:
                 if (!(data & BTRFS_BLOCK_GROUP_DATA))
                         trans->block_group = block_group->key.objectid;
 
-                if (last_ptr)
-                        *last_ptr = ins->objectid + ins->offset;
-                put_block_group(block_group);
+                btrfs_put_block_group(block_group);
                 ret = 0;
         }
 
@@ -2817,7 +2890,7 @@ int btrfs_free_reserved_extent(struct btrfs_root *root, u64 start, u64 len)
         ret = btrfs_discard_extent(root, start, len);
 
         btrfs_add_free_space(cache, start, len);
-        put_block_group(cache);
+        btrfs_put_block_group(cache);
         update_reserved_extents(root, start, len, 0);
 
         return ret;
@@ -2955,7 +3028,7 @@ int btrfs_alloc_logged_extent(struct btrfs_trans_handle *trans,
         ret = btrfs_remove_free_space(block_group, ins->objectid,
                                       ins->offset);
         BUG_ON(ret);
-        put_block_group(block_group);
+        btrfs_put_block_group(block_group);
         ret = __btrfs_alloc_reserved_extent(trans, root, parent, root_objectid,
                                             ref_generation, owner, ins, 1);
         return ret;
@@ -5644,7 +5717,7 @@ next:
         WARN_ON(block_group->reserved > 0);
         WARN_ON(btrfs_block_group_used(&block_group->item) > 0);
         spin_unlock(&block_group->lock);
-        put_block_group(block_group);
+        btrfs_put_block_group(block_group);
         ret = 0;
 out:
         btrfs_free_path(path);
@@ -5774,6 +5847,7 @@ int btrfs_read_block_groups(struct btrfs_root *root)
                 spin_lock_init(&cache->tree_lock);
                 mutex_init(&cache->cache_mutex);
                 INIT_LIST_HEAD(&cache->list);
+                INIT_LIST_HEAD(&cache->cluster_list);
                 read_extent_buffer(leaf, &cache->item,
                                    btrfs_item_ptr_offset(leaf, path->slots[0]),
                                    sizeof(cache->item));
@@ -5830,6 +5904,7 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans,
         spin_lock_init(&cache->tree_lock);
         mutex_init(&cache->cache_mutex);
         INIT_LIST_HEAD(&cache->list);
+        INIT_LIST_HEAD(&cache->cluster_list);
 
         btrfs_set_block_group_used(&cache->item, bytes_used);
         btrfs_set_block_group_chunk_objectid(&cache->item, chunk_objectid);
@@ -5889,8 +5964,8 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
         spin_unlock(&block_group->space_info->lock);
         block_group->space_info->full = 0;
 
-        put_block_group(block_group);
-        put_block_group(block_group);
+        btrfs_put_block_group(block_group);
+        btrfs_put_block_group(block_group);
 
         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
         if (ret > 0)
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index df19b60eef61..3fdadd28e935 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -18,6 +18,15 @@
 
 #include <linux/sched.h>
 #include "ctree.h"
+#include "free-space-cache.h"
+#include "transaction.h"
+
+struct btrfs_free_space {
+        struct rb_node bytes_index;
+        struct rb_node offset_index;
+        u64 offset;
+        u64 bytes;
+};
 
 static int tree_insert_offset(struct rb_root *root, u64 offset,
                               struct rb_node *node)
@@ -371,12 +380,58 @@ u64 btrfs_block_group_free_space(struct btrfs_block_group_cache *block_group)
         return ret;
 }
 
+/*
+ * for a given cluster, put all of its extents back into the free
+ * space cache.  If the block group passed doesn't match the block group
+ * pointed to by the cluster, someone else raced in and freed the
+ * cluster already.  In that case, we just return without changing anything
+ */
+static int
+__btrfs_return_cluster_to_free_space(
+                             struct btrfs_block_group_cache *block_group,
+                             struct btrfs_free_cluster *cluster)
+{
+        struct btrfs_free_space *entry;
+        struct rb_node *node;
+
+        spin_lock(&cluster->lock);
+        if (cluster->block_group != block_group)
+                goto out;
+
+        cluster->window_start = 0;
+        node = rb_first(&cluster->root);
+        while(node) {
+                entry = rb_entry(node, struct btrfs_free_space, offset_index);
+                node = rb_next(&entry->offset_index);
+                rb_erase(&entry->offset_index, &cluster->root);
+                link_free_space(block_group, entry);
+        }
+        list_del_init(&cluster->block_group_list);
+
+        btrfs_put_block_group(cluster->block_group);
+        cluster->block_group = NULL;
+        cluster->root.rb_node = NULL;
+out:
+        spin_unlock(&cluster->lock);
+        return 0;
+}
+
 void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
 {
         struct btrfs_free_space *info;
         struct rb_node *node;
+        struct btrfs_free_cluster *cluster;
+        struct btrfs_free_cluster *safe;
 
         spin_lock(&block_group->tree_lock);
+
+        list_for_each_entry_safe(cluster, safe, &block_group->cluster_list,
+                                 block_group_list) {
+
+                WARN_ON(cluster->block_group != block_group);
+                __btrfs_return_cluster_to_free_space(block_group, cluster);
+        }
+
         while ((node = rb_last(&block_group->free_space_bytes)) != NULL) {
                 info = rb_entry(node, struct btrfs_free_space, bytes_index);
                 unlink_free_space(block_group, info);
@@ -417,3 +472,245 @@ u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
 
         return ret;
 }
+
+/*
+ * given a cluster, put all of its extents back into the free space
+ * cache.  If a block group is passed, this function will only free
+ * a cluster that belongs to the passed block group.
+ *
+ * Otherwise, it'll get a reference on the block group pointed to by the
+ * cluster and remove the cluster from it.
+ */
+int btrfs_return_cluster_to_free_space(
+                               struct btrfs_block_group_cache *block_group,
+                               struct btrfs_free_cluster *cluster)
+{
+        int ret;
+
+        /* first, get a safe pointer to the block group */
+        spin_lock(&cluster->lock);
+        if (!block_group) {
+                block_group = cluster->block_group;
+                if (!block_group) {
+                        spin_unlock(&cluster->lock);
+                        return 0;
+                }
+        } else if (cluster->block_group != block_group) {
+                /* someone else has already freed it don't redo their work */
+                spin_unlock(&cluster->lock);
+                return 0;
+        }
+        atomic_inc(&block_group->count);
+        spin_unlock(&cluster->lock);
+
+        /* now return any extents the cluster had on it */
+        spin_lock(&block_group->tree_lock);
+        ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
+        spin_unlock(&block_group->tree_lock);
+
+        /* finally drop our ref */
+        btrfs_put_block_group(block_group);
+        return ret;
+}
+
+/*
+ * given a cluster, try to allocate 'bytes' from it, returns 0
+ * if it couldn't find anything suitably large, or a logical disk offset
+ * if things worked out
+ */
+u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
+                             struct btrfs_free_cluster *cluster, u64 bytes,
+                             u64 min_start)
+{
+        struct btrfs_free_space *entry = NULL;
+        struct rb_node *node;
+        u64 ret = 0;
+
+        spin_lock(&cluster->lock);
+        if (bytes > cluster->max_size)
+                goto out;
+
+        if (cluster->block_group != block_group)
+                goto out;
+
+        node = rb_first(&cluster->root);
+        if (!node)
+                goto out;
+
+        entry = rb_entry(node, struct btrfs_free_space, offset_index);
+
+        while(1) {
+                if (entry->bytes < bytes || entry->offset < min_start) {
+                        struct rb_node *node;
+
+                        node = rb_next(&entry->offset_index);
+                        if (!node)
+                                break;
+                        entry = rb_entry(node, struct btrfs_free_space,
+                                         offset_index);
+                        continue;
+                }
+                ret = entry->offset;
+
+                entry->offset += bytes;
+                entry->bytes -= bytes;
+
+                if (entry->bytes == 0) {
+                        rb_erase(&entry->offset_index, &cluster->root);
+                        kfree(entry);
+                }
+                break;
+        }
+out:
+        spin_unlock(&cluster->lock);
+        return ret;
+}
+
+/*
+ * here we try to find a cluster of blocks in a block group.  The goal
+ * is to find at least bytes free and up to empty_size + bytes free.
+ * We might not find them all in one contiguous area.
+ *
+ * returns zero and sets up cluster if things worked out, otherwise
+ * it returns -enospc
+ */
+int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
+                             struct btrfs_block_group_cache *block_group,
+                             struct btrfs_free_cluster *cluster,
+                             u64 offset, u64 bytes, u64 empty_size)
+{
+        struct btrfs_free_space *entry = NULL;
+        struct rb_node *node;
+        struct btrfs_free_space *next;
+        struct btrfs_free_space *last;
+        u64 min_bytes;
+        u64 window_start;
+        u64 window_free;
+        u64 max_extent = 0;
+        int total_retries = 0;
+        int ret;
+
+        /* for metadata, allow allocates with more holes */
+        if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
+                /*
+                 * we want to do larger allocations when we are
+                 * flushing out the delayed refs, it helps prevent
+                 * making more work as we go along.
+                 */
+                if (trans->transaction->delayed_refs.flushing)
+                        min_bytes = max(bytes, (bytes + empty_size) >> 1);
+                else
+                        min_bytes = max(bytes, (bytes + empty_size) >> 4);
+        } else
+                min_bytes = max(bytes, (bytes + empty_size) >> 2);
+
+        spin_lock(&block_group->tree_lock);
+        spin_lock(&cluster->lock);
+
+        /* someone already found a cluster, hooray */
+        if (cluster->block_group) {
+                ret = 0;
+                goto out;
+        }
+again:
+        min_bytes = min(min_bytes, bytes + empty_size);
+        entry = tree_search_bytes(&block_group->free_space_bytes,
+                                  offset, min_bytes);
+        if (!entry) {
+                ret = -ENOSPC;
+                goto out;
+        }
+        window_start = entry->offset;
+        window_free = entry->bytes;
+        last = entry;
+        max_extent = entry->bytes;
+
+        while(1) {
+                /* out window is just right, lets fill it */
+                if (window_free >= bytes + empty_size)
+                        break;
+
+                node = rb_next(&last->offset_index);
+                if (!node) {
+                        ret = -ENOSPC;
+                        goto out;
+                }
+                next = rb_entry(node, struct btrfs_free_space, offset_index);
+
+                /*
+                 * we haven't filled the empty size and the window is
+                 * very large.  reset and try again
+                 */
+                if (next->offset - window_start > (bytes + empty_size) * 2) {
+                        entry = next;
+                        window_start = entry->offset;
+                        window_free = entry->bytes;
+                        last = entry;
+                        max_extent = 0;
+                        total_retries++;
+                        if (total_retries % 256 == 0) {
+                                if (min_bytes >= (bytes + empty_size)) {
+                                        ret = -ENOSPC;
+                                        goto out;
+                                }
+                                /*
+                                 * grow our allocation a bit, we're not having
+                                 * much luck
+                                 */
+                                min_bytes *= 2;
+                                goto again;
+                        }
+                } else {
+                        last = next;
+                        window_free += next->bytes;
+                        if (entry->bytes > max_extent)
+                                max_extent = entry->bytes;
+                }
+        }
+
+        cluster->window_start = entry->offset;
+
+        /*
+         * now we've found our entries, pull them out of the free space
+         * cache and put them into the cluster rbtree
+         *
+         * The cluster includes an rbtree, but only uses the offset index
+         * of each free space cache entry.
+         */
+        while(1) {
+                node = rb_next(&entry->offset_index);
+                unlink_free_space(block_group, entry);
+                ret = tree_insert_offset(&cluster->root, entry->offset,
+                                         &entry->offset_index);
+                BUG_ON(ret);
+
+                if (!node || entry == last)
+                        break;
+
+                entry = rb_entry(node, struct btrfs_free_space, offset_index);
+        }
+        ret = 0;
+        cluster->max_size = max_extent;
+        atomic_inc(&block_group->count);
+        list_add_tail(&cluster->block_group_list, &block_group->cluster_list);
+        cluster->block_group = block_group;
+out:
+        spin_unlock(&cluster->lock);
+        spin_unlock(&block_group->tree_lock);
+
+        return ret;
+}
+
+/*
+ * simple code to zero out a cluster
+ */
+void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
+{
+        spin_lock_init(&cluster->lock);
+        spin_lock_init(&cluster->refill_lock);
+        cluster->root.rb_node = NULL;
+        cluster->max_size = 0;
+        INIT_LIST_HEAD(&cluster->block_group_list);
+        cluster->block_group = NULL;
+}
+
diff --git a/fs/btrfs/free-space-cache.h b/fs/btrfs/free-space-cache.h
new file mode 100644
index 000000000000..ab0bdc0a63ce
--- /dev/null
+++ b/fs/btrfs/free-space-cache.h
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2009 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#ifndef __BTRFS_FREE_SPACE_CACHE
+#define __BTRFS_FREE_SPACE_CACHE
+
+int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
+                         u64 bytenr, u64 size);
+int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
+                            u64 bytenr, u64 size);
+void btrfs_remove_free_space_cache(struct btrfs_block_group_cache
+                                   *block_group);
+u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
+                               u64 offset, u64 bytes, u64 empty_size);
+void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
+                           u64 bytes);
+u64 btrfs_block_group_free_space(struct btrfs_block_group_cache *block_group);
+int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
+                             struct btrfs_block_group_cache *block_group,
+                             struct btrfs_free_cluster *cluster,
+                             u64 offset, u64 bytes, u64 empty_size);
+void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster);
+u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
+                             struct btrfs_free_cluster *cluster, u64 bytes,
+                             u64 min_start);
+int btrfs_return_cluster_to_free_space(
+                               struct btrfs_block_group_cache *block_group,
+                               struct btrfs_free_cluster *cluster);
+#endif
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 664782c6a2df..3e8225de4e9d 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -53,8 +53,6 @@ static noinline int join_transaction(struct btrfs_root *root)
                                              GFP_NOFS);
                 BUG_ON(!cur_trans);
                 root->fs_info->generation++;
-                root->fs_info->last_alloc = 0;
-                root->fs_info->last_data_alloc = 0;
                 cur_trans->num_writers = 1;
                 cur_trans->num_joined = 0;
                 cur_trans->transid = root->fs_info->generation;