1 files changed, 1743 insertions, 415 deletions

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index f488fac04d99..bf0d61567f3d 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -23,34 +23,937 @@
 #include "ctree.h"
 #include "free-space-cache.h"
 #include "transaction.h"
+#include "disk-io.h"
+#include "extent_io.h"
+#include "inode-map.h"
 
 #define BITS_PER_BITMAP         (PAGE_CACHE_SIZE * 8)
 #define MAX_CACHE_BYTES_PER_GIG (32 * 1024)
 
-static inline unsigned long offset_to_bit(u64 bitmap_start, u64 sectorsize,
+static int link_free_space(struct btrfs_free_space_ctl *ctl,
+                           struct btrfs_free_space *info);
+
+static struct inode *__lookup_free_space_inode(struct btrfs_root *root,
+                                               struct btrfs_path *path,
+                                               u64 offset)
+{
+        struct btrfs_key key;
+        struct btrfs_key location;
+        struct btrfs_disk_key disk_key;
+        struct btrfs_free_space_header *header;
+        struct extent_buffer *leaf;
+        struct inode *inode = NULL;
+        int ret;
+
+        key.objectid = BTRFS_FREE_SPACE_OBJECTID;
+        key.offset = offset;
+        key.type = 0;
+
+        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+        if (ret < 0)
+                return ERR_PTR(ret);
+        if (ret > 0) {
+                btrfs_release_path(path);
+                return ERR_PTR(-ENOENT);
+        }
+
+        leaf = path->nodes[0];
+        header = btrfs_item_ptr(leaf, path->slots[0],
+                                struct btrfs_free_space_header);
+        btrfs_free_space_key(leaf, header, &disk_key);
+        btrfs_disk_key_to_cpu(&location, &disk_key);
+        btrfs_release_path(path);
+
+        inode = btrfs_iget(root->fs_info->sb, &location, root, NULL);
+        if (!inode)
+                return ERR_PTR(-ENOENT);
+        if (IS_ERR(inode))
+                return inode;
+        if (is_bad_inode(inode)) {
+                iput(inode);
+                return ERR_PTR(-ENOENT);
+        }
+
+        inode->i_mapping->flags &= ~__GFP_FS;
+
+        return inode;
+}
+
+struct inode *lookup_free_space_inode(struct btrfs_root *root,
+                                      struct btrfs_block_group_cache
+                                      *block_group, struct btrfs_path *path)
+{
+        struct inode *inode = NULL;
+
+        spin_lock(&block_group->lock);
+        if (block_group->inode)
+                inode = igrab(block_group->inode);
+        spin_unlock(&block_group->lock);
+        if (inode)
+                return inode;
+
+        inode = __lookup_free_space_inode(root, path,
+                                          block_group->key.objectid);
+        if (IS_ERR(inode))
+                return inode;
+
+        spin_lock(&block_group->lock);
+        if (!btrfs_fs_closing(root->fs_info)) {
+                block_group->inode = igrab(inode);
+                block_group->iref = 1;
+        }
+        spin_unlock(&block_group->lock);
+
+        return inode;
+}
+
+int __create_free_space_inode(struct btrfs_root *root,
+                              struct btrfs_trans_handle *trans,
+                              struct btrfs_path *path, u64 ino, u64 offset)
+{
+        struct btrfs_key key;
+        struct btrfs_disk_key disk_key;
+        struct btrfs_free_space_header *header;
+        struct btrfs_inode_item *inode_item;
+        struct extent_buffer *leaf;
+        int ret;
+
+        ret = btrfs_insert_empty_inode(trans, root, path, ino);
+        if (ret)
+                return ret;
+
+        leaf = path->nodes[0];
+        inode_item = btrfs_item_ptr(leaf, path->slots[0],
+                                    struct btrfs_inode_item);
+        btrfs_item_key(leaf, &disk_key, path->slots[0]);
+        memset_extent_buffer(leaf, 0, (unsigned long)inode_item,
+                             sizeof(*inode_item));
+        btrfs_set_inode_generation(leaf, inode_item, trans->transid);
+        btrfs_set_inode_size(leaf, inode_item, 0);
+        btrfs_set_inode_nbytes(leaf, inode_item, 0);
+        btrfs_set_inode_uid(leaf, inode_item, 0);
+        btrfs_set_inode_gid(leaf, inode_item, 0);
+        btrfs_set_inode_mode(leaf, inode_item, S_IFREG | 0600);
+        btrfs_set_inode_flags(leaf, inode_item, BTRFS_INODE_NOCOMPRESS |
+                              BTRFS_INODE_PREALLOC | BTRFS_INODE_NODATASUM);
+        btrfs_set_inode_nlink(leaf, inode_item, 1);
+        btrfs_set_inode_transid(leaf, inode_item, trans->transid);
+        btrfs_set_inode_block_group(leaf, inode_item, offset);
+        btrfs_mark_buffer_dirty(leaf);
+        btrfs_release_path(path);
+
+        key.objectid = BTRFS_FREE_SPACE_OBJECTID;
+        key.offset = offset;
+        key.type = 0;
+
+        ret = btrfs_insert_empty_item(trans, root, path, &key,
+                                      sizeof(struct btrfs_free_space_header));
+        if (ret < 0) {
+                btrfs_release_path(path);
+                return ret;
+        }
+        leaf = path->nodes[0];
+        header = btrfs_item_ptr(leaf, path->slots[0],
+                                struct btrfs_free_space_header);
+        memset_extent_buffer(leaf, 0, (unsigned long)header, sizeof(*header));
+        btrfs_set_free_space_key(leaf, header, &disk_key);
+        btrfs_mark_buffer_dirty(leaf);
+        btrfs_release_path(path);
+
+        return 0;
+}
+
+int create_free_space_inode(struct btrfs_root *root,
+                            struct btrfs_trans_handle *trans,
+                            struct btrfs_block_group_cache *block_group,
+                            struct btrfs_path *path)
+{
+        int ret;
+        u64 ino;
+
+        ret = btrfs_find_free_objectid(root, &ino);
+        if (ret < 0)
+                return ret;
+
+        return __create_free_space_inode(root, trans, path, ino,
+                                         block_group->key.objectid);
+}
+
+int btrfs_truncate_free_space_cache(struct btrfs_root *root,
+                                    struct btrfs_trans_handle *trans,
+                                    struct btrfs_path *path,
+                                    struct inode *inode)
+{
+        loff_t oldsize;
+        int ret = 0;
+
+        trans->block_rsv = root->orphan_block_rsv;
+        ret = btrfs_block_rsv_check(trans, root,
+                                    root->orphan_block_rsv,
+                                    0, 5);
+        if (ret)
+                return ret;
+
+        oldsize = i_size_read(inode);
+        btrfs_i_size_write(inode, 0);
+        truncate_pagecache(inode, oldsize, 0);
+
+        /*
+         * We don't need an orphan item because truncating the free space cache
+         * will never be split across transactions.
+         */
+        ret = btrfs_truncate_inode_items(trans, root, inode,
+                                         0, BTRFS_EXTENT_DATA_KEY);
+        if (ret) {
+                WARN_ON(1);
+                return ret;
+        }
+
+        ret = btrfs_update_inode(trans, root, inode);
+        return ret;
+}
+
+static int readahead_cache(struct inode *inode)
+{
+        struct file_ra_state *ra;
+        unsigned long last_index;
+
+        ra = kzalloc(sizeof(*ra), GFP_NOFS);
+        if (!ra)
+                return -ENOMEM;
+
+        file_ra_state_init(ra, inode->i_mapping);
+        last_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
+
+        page_cache_sync_readahead(inode->i_mapping, ra, NULL, 0, last_index);
+
+        kfree(ra);
+
+        return 0;
+}
+
+int __load_free_space_cache(struct btrfs_root *root, struct inode *inode,
+                            struct btrfs_free_space_ctl *ctl,
+                            struct btrfs_path *path, u64 offset)
+{
+        struct btrfs_free_space_header *header;
+        struct extent_buffer *leaf;
+        struct page *page;
+        u32 *checksums = NULL, *crc;
+        char *disk_crcs = NULL;
+        struct btrfs_key key;
+        struct list_head bitmaps;
+        u64 num_entries;
+        u64 num_bitmaps;
+        u64 generation;
+        u32 cur_crc = ~(u32)0;
+        pgoff_t index = 0;
+        unsigned long first_page_offset;
+        int num_checksums;
+        int ret = 0;
+
+        INIT_LIST_HEAD(&bitmaps);
+
+        /* Nothing in the space cache, goodbye */
+        if (!i_size_read(inode))
+                goto out;
+
+        key.objectid = BTRFS_FREE_SPACE_OBJECTID;
+        key.offset = offset;
+        key.type = 0;
+
+        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+        if (ret < 0)
+                goto out;
+        else if (ret > 0) {
+                btrfs_release_path(path);
+                ret = 0;
+                goto out;
+        }
+
+        ret = -1;
+
+        leaf = path->nodes[0];
+        header = btrfs_item_ptr(leaf, path->slots[0],
+                                struct btrfs_free_space_header);
+        num_entries = btrfs_free_space_entries(leaf, header);
+        num_bitmaps = btrfs_free_space_bitmaps(leaf, header);
+        generation = btrfs_free_space_generation(leaf, header);
+        btrfs_release_path(path);
+
+        if (BTRFS_I(inode)->generation != generation) {
+                printk(KERN_ERR "btrfs: free space inode generation (%llu) did"
+                       " not match free space cache generation (%llu)\n",
+                       (unsigned long long)BTRFS_I(inode)->generation,
+                       (unsigned long long)generation);
+                goto out;
+        }
+
+        if (!num_entries)
+                goto out;
+
+        /* Setup everything for doing checksumming */
+        num_checksums = i_size_read(inode) / PAGE_CACHE_SIZE;
+        checksums = crc = kzalloc(sizeof(u32) * num_checksums, GFP_NOFS);
+        if (!checksums)
+                goto out;
+        first_page_offset = (sizeof(u32) * num_checksums) + sizeof(u64);
+        disk_crcs = kzalloc(first_page_offset, GFP_NOFS);
+        if (!disk_crcs)
+                goto out;
+
+        ret = readahead_cache(inode);
+        if (ret)
+                goto out;
+
+        while (1) {
+                struct btrfs_free_space_entry *entry;
+                struct btrfs_free_space *e;
+                void *addr;
+                unsigned long offset = 0;
+                unsigned long start_offset = 0;
+                int need_loop = 0;
+
+                if (!num_entries && !num_bitmaps)
+                        break;
+
+                if (index == 0) {
+                        start_offset = first_page_offset;
+                        offset = start_offset;
+                }
+
+                page = grab_cache_page(inode->i_mapping, index);
+                if (!page)
+                        goto free_cache;
+
+                if (!PageUptodate(page)) {
+                        btrfs_readpage(NULL, page);
+                        lock_page(page);
+                        if (!PageUptodate(page)) {
+                                unlock_page(page);
+                                page_cache_release(page);
+                                printk(KERN_ERR "btrfs: error reading free "
+                                       "space cache\n");
+                                goto free_cache;
+                        }
+                }
+                addr = kmap(page);
+
+                if (index == 0) {
+                        u64 *gen;
+
+                        memcpy(disk_crcs, addr, first_page_offset);
+                        gen = addr + (sizeof(u32) * num_checksums);
+                        if (*gen != BTRFS_I(inode)->generation) {
+                                printk(KERN_ERR "btrfs: space cache generation"
+                                       " (%llu) does not match inode (%llu)\n",
+                                       (unsigned long long)*gen,
+                                       (unsigned long long)
+                                       BTRFS_I(inode)->generation);
+                                kunmap(page);
+                                unlock_page(page);
+                                page_cache_release(page);
+                                goto free_cache;
+                        }
+                        crc = (u32 *)disk_crcs;
+                }
+                entry = addr + start_offset;
+
+                /* First lets check our crc before we do anything fun */
+                cur_crc = ~(u32)0;
+                cur_crc = btrfs_csum_data(root, addr + start_offset, cur_crc,
+                                          PAGE_CACHE_SIZE - start_offset);
+                btrfs_csum_final(cur_crc, (char *)&cur_crc);
+                if (cur_crc != *crc) {
+                        printk(KERN_ERR "btrfs: crc mismatch for page %lu\n",
+                               index);
+                        kunmap(page);
+                        unlock_page(page);
+                        page_cache_release(page);
+                        goto free_cache;
+                }
+                crc++;
+
+                while (1) {
+                        if (!num_entries)
+                                break;
+
+                        need_loop = 1;
+                        e = kmem_cache_zalloc(btrfs_free_space_cachep,
+                                              GFP_NOFS);
+                        if (!e) {
+                                kunmap(page);
+                                unlock_page(page);
+                                page_cache_release(page);
+                                goto free_cache;
+                        }
+
+                        e->offset = le64_to_cpu(entry->offset);
+                        e->bytes = le64_to_cpu(entry->bytes);
+                        if (!e->bytes) {
+                                kunmap(page);
+                                kmem_cache_free(btrfs_free_space_cachep, e);
+                                unlock_page(page);
+                                page_cache_release(page);
+                                goto free_cache;
+                        }
+
+                        if (entry->type == BTRFS_FREE_SPACE_EXTENT) {
+                                spin_lock(&ctl->tree_lock);
+                                ret = link_free_space(ctl, e);
+                                spin_unlock(&ctl->tree_lock);
+                                if (ret) {
+                                        printk(KERN_ERR "Duplicate entries in "
+                                               "free space cache, dumping\n");
+                                        kunmap(page);
+                                        unlock_page(page);
+                                        page_cache_release(page);
+                                        goto free_cache;
+                                }
+                        } else {
+                                e->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
+                                if (!e->bitmap) {
+                                        kunmap(page);
+                                        kmem_cache_free(
+                                                btrfs_free_space_cachep, e);
+                                        unlock_page(page);
+                                        page_cache_release(page);
+                                        goto free_cache;
+                                }
+                                spin_lock(&ctl->tree_lock);
+                                ret = link_free_space(ctl, e);
+                                ctl->total_bitmaps++;
+                                ctl->op->recalc_thresholds(ctl);
+                                spin_unlock(&ctl->tree_lock);
+                                if (ret) {
+                                        printk(KERN_ERR "Duplicate entries in "
+                                               "free space cache, dumping\n");
+                                        kunmap(page);
+                                        unlock_page(page);
+                                        page_cache_release(page);
+                                        goto free_cache;
+                                }
+                                list_add_tail(&e->list, &bitmaps);
+                        }
+
+                        num_entries--;
+                        offset += sizeof(struct btrfs_free_space_entry);
+                        if (offset + sizeof(struct btrfs_free_space_entry) >=
+                            PAGE_CACHE_SIZE)
+                                break;
+                        entry++;
+                }
+
+                /*
+                 * We read an entry out of this page, we need to move on to the
+                 * next page.
+                 */
+                if (need_loop) {
+                        kunmap(page);
+                        goto next;
+                }
+
+                /*
+                 * We add the bitmaps at the end of the entries in order that
+                 * the bitmap entries are added to the cache.
+                 */
+                e = list_entry(bitmaps.next, struct btrfs_free_space, list);
+                list_del_init(&e->list);
+                memcpy(e->bitmap, addr, PAGE_CACHE_SIZE);
+                kunmap(page);
+                num_bitmaps--;
+next:
+                unlock_page(page);
+                page_cache_release(page);
+                index++;
+        }
+
+        ret = 1;
+out:
+        kfree(checksums);
+        kfree(disk_crcs);
+        return ret;
+free_cache:
+        __btrfs_remove_free_space_cache(ctl);
+        goto out;
+}
+
+int load_free_space_cache(struct btrfs_fs_info *fs_info,
+                          struct btrfs_block_group_cache *block_group)
+{
+        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
+        struct btrfs_root *root = fs_info->tree_root;
+        struct inode *inode;
+        struct btrfs_path *path;
+        int ret;
+        bool matched;
+        u64 used = btrfs_block_group_used(&block_group->item);
+
+        /*
+         * If we're unmounting then just return, since this does a search on the
+         * normal root and not the commit root and we could deadlock.
+         */
+        if (btrfs_fs_closing(fs_info))
+                return 0;
+
+        /*
+         * If this block group has been marked to be cleared for one reason or
+         * another then we can't trust the on disk cache, so just return.
+         */
+        spin_lock(&block_group->lock);
+        if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
+                spin_unlock(&block_group->lock);
+                return 0;
+        }
+        spin_unlock(&block_group->lock);
+
+        path = btrfs_alloc_path();
+        if (!path)
+                return 0;
+
+        inode = lookup_free_space_inode(root, block_group, path);
+        if (IS_ERR(inode)) {
+                btrfs_free_path(path);
+                return 0;
+        }
+
+        ret = __load_free_space_cache(fs_info->tree_root, inode, ctl,
+                                      path, block_group->key.objectid);
+        btrfs_free_path(path);
+        if (ret <= 0)
+                goto out;
+
+        spin_lock(&ctl->tree_lock);
+        matched = (ctl->free_space == (block_group->key.offset - used -
+                                       block_group->bytes_super));
+        spin_unlock(&ctl->tree_lock);
+
+        if (!matched) {
+                __btrfs_remove_free_space_cache(ctl);
+                printk(KERN_ERR "block group %llu has an wrong amount of free "
+                       "space\n", block_group->key.objectid);
+                ret = -1;
+        }
+out:
+        if (ret < 0) {
+                /* This cache is bogus, make sure it gets cleared */
+                spin_lock(&block_group->lock);
+                block_group->disk_cache_state = BTRFS_DC_CLEAR;
+                spin_unlock(&block_group->lock);
+                ret = 0;
+
+                printk(KERN_ERR "btrfs: failed to load free space cache "
+                       "for block group %llu\n", block_group->key.objectid);
+        }
+
+        iput(inode);
+        return ret;
+}
+
+int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
+                            struct btrfs_free_space_ctl *ctl,
+                            struct btrfs_block_group_cache *block_group,
+                            struct btrfs_trans_handle *trans,
+                            struct btrfs_path *path, u64 offset)
+{
+        struct btrfs_free_space_header *header;
+        struct extent_buffer *leaf;
+        struct rb_node *node;
+        struct list_head *pos, *n;
+        struct page **pages;
+        struct page *page;
+        struct extent_state *cached_state = NULL;
+        struct btrfs_free_cluster *cluster = NULL;
+        struct extent_io_tree *unpin = NULL;
+        struct list_head bitmap_list;
+        struct btrfs_key key;
+        u64 start, end, len;
+        u64 bytes = 0;
+        u32 *crc, *checksums;
+        unsigned long first_page_offset;
+        int index = 0, num_pages = 0;
+        int entries = 0;
+        int bitmaps = 0;
+        int ret = -1;
+        bool next_page = false;
+        bool out_of_space = false;
+
+        INIT_LIST_HEAD(&bitmap_list);
+
+        node = rb_first(&ctl->free_space_offset);
+        if (!node)
+                return 0;
+
+        if (!i_size_read(inode))
+                return -1;
+
+        num_pages = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
+                PAGE_CACHE_SHIFT;
+
+        /* Since the first page has all of our checksums and our generation we
+         * need to calculate the offset into the page that we can start writing
+         * our entries.
+         */
+        first_page_offset = (sizeof(u32) * num_pages) + sizeof(u64);
+
+        filemap_write_and_wait(inode->i_mapping);
+        btrfs_wait_ordered_range(inode, inode->i_size &
+                                 ~(root->sectorsize - 1), (u64)-1);
+
+        /* make sure we don't overflow that first page */
+        if (first_page_offset + sizeof(struct btrfs_free_space_entry) >= PAGE_CACHE_SIZE) {
+                /* this is really the same as running out of space, where we also return 0 */
+                printk(KERN_CRIT "Btrfs: free space cache was too big for the crc page\n");
+                ret = 0;
+                goto out_update;
+        }
+
+        /* We need a checksum per page. */
+        crc = checksums = kzalloc(sizeof(u32) * num_pages, GFP_NOFS);
+        if (!crc)
+                return -1;
+
+        pages = kzalloc(sizeof(struct page *) * num_pages, GFP_NOFS);
+        if (!pages) {
+                kfree(crc);
+                return -1;
+        }
+
+        /* Get the cluster for this block_group if it exists */
+        if (block_group && !list_empty(&block_group->cluster_list))
+                cluster = list_entry(block_group->cluster_list.next,
+                                     struct btrfs_free_cluster,
+                                     block_group_list);
+
+        /*
+         * We shouldn't have switched the pinned extents yet so this is the
+         * right one
+         */
+        unpin = root->fs_info->pinned_extents;
+
+        /*
+         * Lock all pages first so we can lock the extent safely.
+         *
+         * NOTE: Because we hold the ref the entire time we're going to write to
+         * the page find_get_page should never fail, so we don't do a check
+         * after find_get_page at this point.  Just putting this here so people
+         * know and don't freak out.
+         */
+        while (index < num_pages) {
+                page = grab_cache_page(inode->i_mapping, index);
+                if (!page) {
+                        int i;
+
+                        for (i = 0; i < num_pages; i++) {
+                                unlock_page(pages[i]);
+                                page_cache_release(pages[i]);
+                        }
+                        goto out_free;
+                }
+                pages[index] = page;
+                index++;
+        }
+
+        index = 0;
+        lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
+                         0, &cached_state, GFP_NOFS);
+
+        /*
+         * When searching for pinned extents, we need to start at our start
+         * offset.
+         */
+        if (block_group)
+                start = block_group->key.objectid;
+
+        /* Write out the extent entries */
+        do {
+                struct btrfs_free_space_entry *entry;
+                void *addr;
+                unsigned long offset = 0;
+                unsigned long start_offset = 0;
+
+                next_page = false;
+
+                if (index == 0) {
+                        start_offset = first_page_offset;
+                        offset = start_offset;
+                }
+
+                if (index >= num_pages) {
+                        out_of_space = true;
+                        break;
+                }
+
+                page = pages[index];
+
+                addr = kmap(page);
+                entry = addr + start_offset;
+
+                memset(addr, 0, PAGE_CACHE_SIZE);
+                while (node && !next_page) {
+                        struct btrfs_free_space *e;
+
+                        e = rb_entry(node, struct btrfs_free_space, offset_index);
+                        entries++;
+
+                        entry->offset = cpu_to_le64(e->offset);
+                        entry->bytes = cpu_to_le64(e->bytes);
+                        if (e->bitmap) {
+                                entry->type = BTRFS_FREE_SPACE_BITMAP;
+                                list_add_tail(&e->list, &bitmap_list);
+                                bitmaps++;
+                        } else {
+                                entry->type = BTRFS_FREE_SPACE_EXTENT;
+                        }
+                        node = rb_next(node);
+                        if (!node && cluster) {
+                                node = rb_first(&cluster->root);
+                                cluster = NULL;
+                        }
+                        offset += sizeof(struct btrfs_free_space_entry);
+                        if (offset + sizeof(struct btrfs_free_space_entry) >=
+                            PAGE_CACHE_SIZE)
+                                next_page = true;
+                        entry++;
+                }
+
+                /*
+                 * We want to add any pinned extents to our free space cache
+                 * so we don't leak the space
+                 */
+                while (block_group && !next_page &&
+                       (start < block_group->key.objectid +
+                        block_group->key.offset)) {
+                        ret = find_first_extent_bit(unpin, start, &start, &end,
+                                                    EXTENT_DIRTY);
+                        if (ret) {
+                                ret = 0;
+                                break;
+                        }
+
+                        /* This pinned extent is out of our range */
+                        if (start >= block_group->key.objectid +
+                            block_group->key.offset)
+                                break;
+
+                        len = block_group->key.objectid +
+                                block_group->key.offset - start;
+                        len = min(len, end + 1 - start);
+
+                        entries++;
+                        entry->offset = cpu_to_le64(start);
+                        entry->bytes = cpu_to_le64(len);
+                        entry->type = BTRFS_FREE_SPACE_EXTENT;
+
+                        start = end + 1;
+                        offset += sizeof(struct btrfs_free_space_entry);
+                        if (offset + sizeof(struct btrfs_free_space_entry) >=
+                            PAGE_CACHE_SIZE)
+                                next_page = true;
+                        entry++;
+                }
+                *crc = ~(u32)0;
+                *crc = btrfs_csum_data(root, addr + start_offset, *crc,
+                                       PAGE_CACHE_SIZE - start_offset);
+                kunmap(page);
+
+                btrfs_csum_final(*crc, (char *)crc);
+                crc++;
+
+                bytes += PAGE_CACHE_SIZE;
+
+                index++;
+        } while (node || next_page);
+
+        /* Write out the bitmaps */
+        list_for_each_safe(pos, n, &bitmap_list) {
+                void *addr;
+                struct btrfs_free_space *entry =
+                        list_entry(pos, struct btrfs_free_space, list);
+
+                if (index >= num_pages) {
+                        out_of_space = true;
+                        break;
+                }
+                page = pages[index];
+
+                addr = kmap(page);
+                memcpy(addr, entry->bitmap, PAGE_CACHE_SIZE);
+                *crc = ~(u32)0;
+                *crc = btrfs_csum_data(root, addr, *crc, PAGE_CACHE_SIZE);
+                kunmap(page);
+                btrfs_csum_final(*crc, (char *)crc);
+                crc++;
+                bytes += PAGE_CACHE_SIZE;
+
+                list_del_init(&entry->list);
+                index++;
+        }
+
+        if (out_of_space) {
+                btrfs_drop_pages(pages, num_pages);
+                unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
+                                     i_size_read(inode) - 1, &cached_state,
+                                     GFP_NOFS);
+                ret = 0;
+                goto out_free;
+        }
+
+        /* Zero out the rest of the pages just to make sure */
+        while (index < num_pages) {
+                void *addr;
+
+                page = pages[index];
+                addr = kmap(page);
+                memset(addr, 0, PAGE_CACHE_SIZE);
+                kunmap(page);
+                bytes += PAGE_CACHE_SIZE;
+                index++;
+        }
+
+        /* Write the checksums and trans id to the first page */
+        {
+                void *addr;
+                u64 *gen;
+
+                page = pages[0];
+
+                addr = kmap(page);
+                memcpy(addr, checksums, sizeof(u32) * num_pages);
+                gen = addr + (sizeof(u32) * num_pages);
+                *gen = trans->transid;
+                kunmap(page);
+        }
+
+        ret = btrfs_dirty_pages(root, inode, pages, num_pages, 0,
+                                            bytes, &cached_state);
+        btrfs_drop_pages(pages, num_pages);
+        unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
+                             i_size_read(inode) - 1, &cached_state, GFP_NOFS);
+
+        if (ret) {
+                ret = 0;
+                goto out_free;
+        }
+
+        BTRFS_I(inode)->generation = trans->transid;
+
+        filemap_write_and_wait(inode->i_mapping);
+
+        key.objectid = BTRFS_FREE_SPACE_OBJECTID;
+        key.offset = offset;
+        key.type = 0;
+
+        ret = btrfs_search_slot(trans, root, &key, path, 1, 1);
+        if (ret < 0) {
+                ret = -1;
+                clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
+                                 EXTENT_DIRTY | EXTENT_DELALLOC |
+                                 EXTENT_DO_ACCOUNTING, 0, 0, NULL, GFP_NOFS);
+                goto out_free;
+        }
+        leaf = path->nodes[0];
+        if (ret > 0) {
+                struct btrfs_key found_key;
+                BUG_ON(!path->slots[0]);
+                path->slots[0]--;
+                btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+                if (found_key.objectid != BTRFS_FREE_SPACE_OBJECTID ||
+                    found_key.offset != offset) {
+                        ret = -1;
+                        clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
+                                         EXTENT_DIRTY | EXTENT_DELALLOC |
+                                         EXTENT_DO_ACCOUNTING, 0, 0, NULL,
+                                         GFP_NOFS);
+                        btrfs_release_path(path);
+                        goto out_free;
+                }
+        }
+        header = btrfs_item_ptr(leaf, path->slots[0],
+                                struct btrfs_free_space_header);
+        btrfs_set_free_space_entries(leaf, header, entries);
+        btrfs_set_free_space_bitmaps(leaf, header, bitmaps);
+        btrfs_set_free_space_generation(leaf, header, trans->transid);
+        btrfs_mark_buffer_dirty(leaf);
+        btrfs_release_path(path);
+
+        ret = 1;
+
+out_free:
+        kfree(checksums);
+        kfree(pages);
+
+out_update:
+        if (ret != 1) {
+                invalidate_inode_pages2_range(inode->i_mapping, 0, index);
+                BTRFS_I(inode)->generation = 0;
+        }
+        btrfs_update_inode(trans, root, inode);
+        return ret;
+}
+
+int btrfs_write_out_cache(struct btrfs_root *root,
+                          struct btrfs_trans_handle *trans,
+                          struct btrfs_block_group_cache *block_group,
+                          struct btrfs_path *path)
+{
+        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
+        struct inode *inode;
+        int ret = 0;
+
+        root = root->fs_info->tree_root;
+
+        spin_lock(&block_group->lock);
+        if (block_group->disk_cache_state < BTRFS_DC_SETUP) {
+                spin_unlock(&block_group->lock);
+                return 0;
+        }
+        spin_unlock(&block_group->lock);
+
+        inode = lookup_free_space_inode(root, block_group, path);
+        if (IS_ERR(inode))
+                return 0;
+
+        ret = __btrfs_write_out_cache(root, inode, ctl, block_group, trans,
+                                      path, block_group->key.objectid);
+        if (ret < 0) {
+                spin_lock(&block_group->lock);
+                block_group->disk_cache_state = BTRFS_DC_ERROR;
+                spin_unlock(&block_group->lock);
+                ret = 0;
+
+                printk(KERN_ERR "btrfs: failed to write free space cace "
+                       "for block group %llu\n", block_group->key.objectid);
+        }
+
+        iput(inode);
+        return ret;
+}
+
+static inline unsigned long offset_to_bit(u64 bitmap_start, u32 unit,
                                           u64 offset)
 {
         BUG_ON(offset < bitmap_start);
         offset -= bitmap_start;
-        return (unsigned long)(div64_u64(offset, sectorsize));
+        return (unsigned long)(div_u64(offset, unit));
 }
 
-static inline unsigned long bytes_to_bits(u64 bytes, u64 sectorsize)
+static inline unsigned long bytes_to_bits(u64 bytes, u32 unit)
 {
-        return (unsigned long)(div64_u64(bytes, sectorsize));
+        return (unsigned long)(div_u64(bytes, unit));
 }
 
-static inline u64 offset_to_bitmap(struct btrfs_block_group_cache *block_group,
+static inline u64 offset_to_bitmap(struct btrfs_free_space_ctl *ctl,
                                    u64 offset)
 {
         u64 bitmap_start;
         u64 bytes_per_bitmap;
 
-        bytes_per_bitmap = BITS_PER_BITMAP * block_group->sectorsize;
-        bitmap_start = offset - block_group->key.objectid;
+        bytes_per_bitmap = BITS_PER_BITMAP * ctl->unit;
+        bitmap_start = offset - ctl->start;
         bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
         bitmap_start *= bytes_per_bitmap;
-        bitmap_start += block_group->key.objectid;
+        bitmap_start += ctl->start;
 
         return bitmap_start;
 }
@@ -85,10 +988,16 @@ static int tree_insert_offset(struct rb_root *root, u64 offset,
                          * logically.
                          */
                         if (bitmap) {
-                                WARN_ON(info->bitmap);
+                                if (info->bitmap) {
+                                        WARN_ON_ONCE(1);
+                                        return -EEXIST;
+                                }
                                 p = &(*p)->rb_right;
                         } else {
-                                WARN_ON(!info->bitmap);
+                                if (!info->bitmap) {
+                                        WARN_ON_ONCE(1);
+                                        return -EEXIST;
+                                }
                                 p = &(*p)->rb_left;
                         }
                 }
@@ -108,10 +1017,10 @@ static int tree_insert_offset(struct rb_root *root, u64 offset,
  * offset.
  */
 static struct btrfs_free_space *
-tree_search_offset(struct btrfs_block_group_cache *block_group,
+tree_search_offset(struct btrfs_free_space_ctl *ctl,
                    u64 offset, int bitmap_only, int fuzzy)
 {
-        struct rb_node *n = block_group->free_space_offset.rb_node;
+        struct rb_node *n = ctl->free_space_offset.rb_node;
         struct btrfs_free_space *entry, *prev = NULL;
 
         /* find entry that is closest to the 'offset' */
@@ -207,8 +1116,7 @@ tree_search_offset(struct btrfs_block_group_cache *block_group,
                                 break;
                         }
                 }
-                if (entry->offset + BITS_PER_BITMAP *
-                    block_group->sectorsize > offset)
+                if (entry->offset + BITS_PER_BITMAP * ctl->unit > offset)
                         return entry;
         } else if (entry->offset + entry->bytes > offset)
                 return entry;
@@ -219,7 +1127,7 @@ tree_search_offset(struct btrfs_block_group_cache *block_group,
         while (1) {
                 if (entry->bitmap) {
                         if (entry->offset + BITS_PER_BITMAP *
-                            block_group->sectorsize > offset)
+                            ctl->unit > offset)
                                 break;
                 } else {
                         if (entry->offset + entry->bytes > offset)
@@ -234,53 +1142,69 @@ tree_search_offset(struct btrfs_block_group_cache *block_group,
         return entry;
 }
 
-static void unlink_free_space(struct btrfs_block_group_cache *block_group,
+static inline void
+__unlink_free_space(struct btrfs_free_space_ctl *ctl,
+                    struct btrfs_free_space *info)
+{
+        rb_erase(&info->offset_index, &ctl->free_space_offset);
+        ctl->free_extents--;
+}
+
+static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
                               struct btrfs_free_space *info)
 {
-        rb_erase(&info->offset_index, &block_group->free_space_offset);
-        block_group->free_extents--;
-        block_group->free_space -= info->bytes;
+        __unlink_free_space(ctl, info);
+        ctl->free_space -= info->bytes;
 }
 
-static int link_free_space(struct btrfs_block_group_cache *block_group,
+static int link_free_space(struct btrfs_free_space_ctl *ctl,
                            struct btrfs_free_space *info)
 {
         int ret = 0;
 
         BUG_ON(!info->bitmap && !info->bytes);
-        ret = tree_insert_offset(&block_group->free_space_offset, info->offset,
+        ret = tree_insert_offset(&ctl->free_space_offset, info->offset,
                                  &info->offset_index, (info->bitmap != NULL));
         if (ret)
                 return ret;
 
-        block_group->free_space += info->bytes;
-        block_group->free_extents++;
+        ctl->free_space += info->bytes;
+        ctl->free_extents++;
         return ret;
 }
 
-static void recalculate_thresholds(struct btrfs_block_group_cache *block_group)
+static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
 {
+        struct btrfs_block_group_cache *block_group = ctl->private;
         u64 max_bytes;
         u64 bitmap_bytes;
         u64 extent_bytes;
+        u64 size = block_group->key.offset;
+        u64 bytes_per_bg = BITS_PER_BITMAP * block_group->sectorsize;
+        int max_bitmaps = div64_u64(size + bytes_per_bg - 1, bytes_per_bg);
+
+        BUG_ON(ctl->total_bitmaps > max_bitmaps);
 
         /*
          * The goal is to keep the total amount of memory used per 1gb of space
          * at or below 32k, so we need to adjust how much memory we allow to be
          * used by extent based free space tracking
          */
-        max_bytes = MAX_CACHE_BYTES_PER_GIG *
-                (div64_u64(block_group->key.offset, 1024 * 1024 * 1024));
+        if (size < 1024 * 1024 * 1024)
+                max_bytes = MAX_CACHE_BYTES_PER_GIG;
+        else
+                max_bytes = MAX_CACHE_BYTES_PER_GIG *
+                        div64_u64(size, 1024 * 1024 * 1024);
 
         /*
          * we want to account for 1 more bitmap than what we have so we can make
          * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
          * we add more bitmaps.
          */
-        bitmap_bytes = (block_group->total_bitmaps + 1) * PAGE_CACHE_SIZE;
+        bitmap_bytes = (ctl->total_bitmaps + 1) * PAGE_CACHE_SIZE;
 
         if (bitmap_bytes >= max_bytes) {
-                block_group->extents_thresh = 0;
+                ctl->extents_thresh = 0;
                 return;
         }
 
@@ -291,47 +1215,43 @@ static void recalculate_thresholds(struct btrfs_block_group_cache *block_group)
         extent_bytes = max_bytes - bitmap_bytes;
         extent_bytes = min_t(u64, extent_bytes, div64_u64(max_bytes, 2));
 
-        block_group->extents_thresh =
+        ctl->extents_thresh =
                 div64_u64(extent_bytes, (sizeof(struct btrfs_free_space)));
 }
 
-static void bitmap_clear_bits(struct btrfs_block_group_cache *block_group,
+static void bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
                               struct btrfs_free_space *info, u64 offset,
                               u64 bytes)
 {
-        unsigned long start, end;
-        unsigned long i;
+        unsigned long start, count;
 
-        start = offset_to_bit(info->offset, block_group->sectorsize, offset);
-        end = start + bytes_to_bits(bytes, block_group->sectorsize);
-        BUG_ON(end > BITS_PER_BITMAP);
+        start = offset_to_bit(info->offset, ctl->unit, offset);
+        count = bytes_to_bits(bytes, ctl->unit);
+        BUG_ON(start + count > BITS_PER_BITMAP);
 
-        for (i = start; i < end; i++)
-                clear_bit(i, info->bitmap);
+        bitmap_clear(info->bitmap, start, count);
 
         info->bytes -= bytes;
-        block_group->free_space -= bytes;
+        ctl->free_space -= bytes;
 }
 
-static void bitmap_set_bits(struct btrfs_block_group_cache *block_group,
+static void bitmap_set_bits(struct btrfs_free_space_ctl *ctl,
                             struct btrfs_free_space *info, u64 offset,
                             u64 bytes)
 {
-        unsigned long start, end;
-        unsigned long i;
+        unsigned long start, count;
 
-        start = offset_to_bit(info->offset, block_group->sectorsize, offset);
-        end = start + bytes_to_bits(bytes, block_group->sectorsize);
-        BUG_ON(end > BITS_PER_BITMAP);
+        start = offset_to_bit(info->offset, ctl->unit, offset);
+        count = bytes_to_bits(bytes, ctl->unit);
+        BUG_ON(start + count > BITS_PER_BITMAP);
 
-        for (i = start; i < end; i++)
-                set_bit(i, info->bitmap);
+        bitmap_set(info->bitmap, start, count);
 
         info->bytes += bytes;
-        block_group->free_space += bytes;
+        ctl->free_space += bytes;
 }
 
-static int search_bitmap(struct btrfs_block_group_cache *block_group,
+static int search_bitmap(struct btrfs_free_space_ctl *ctl,
                          struct btrfs_free_space *bitmap_info, u64 *offset,
                          u64 *bytes)
 {
@@ -339,9 +1259,9 @@ static int search_bitmap(struct btrfs_block_group_cache *block_group,
         unsigned long bits, i;
         unsigned long next_zero;
 
-        i = offset_to_bit(bitmap_info->offset, block_group->sectorsize,
+        i = offset_to_bit(bitmap_info->offset, ctl->unit,
                           max_t(u64, *offset, bitmap_info->offset));
-        bits = bytes_to_bits(*bytes, block_group->sectorsize);
+        bits = bytes_to_bits(*bytes, ctl->unit);
 
         for (i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i);
              i < BITS_PER_BITMAP;
@@ -356,29 +1276,25 @@ static int search_bitmap(struct btrfs_block_group_cache *block_group,
         }
 
         if (found_bits) {
-                *offset = (u64)(i * block_group->sectorsize) +
-                        bitmap_info->offset;
-                *bytes = (u64)(found_bits) * block_group->sectorsize;
+                *offset = (u64)(i * ctl->unit) + bitmap_info->offset;
+                *bytes = (u64)(found_bits) * ctl->unit;
                 return 0;
         }
 
         return -1;
 }
 
-static struct btrfs_free_space *find_free_space(struct btrfs_block_group_cache
-                                                *block_group, u64 *offset,
-                                                u64 *bytes, int debug)
+static struct btrfs_free_space *
+find_free_space(struct btrfs_free_space_ctl *ctl, u64 *offset, u64 *bytes)
 {
         struct btrfs_free_space *entry;
         struct rb_node *node;
         int ret;
 
-        if (!block_group->free_space_offset.rb_node)
+        if (!ctl->free_space_offset.rb_node)
                 return NULL;
 
-        entry = tree_search_offset(block_group,
-                                   offset_to_bitmap(block_group, *offset),
-                                   0, 1);
+        entry = tree_search_offset(ctl, offset_to_bitmap(ctl, *offset), 0, 1);
         if (!entry)
                 return NULL;
 
@@ -388,7 +1304,7 @@ static struct btrfs_free_space *find_free_space(struct btrfs_block_group_cache
                         continue;
 
                 if (entry->bitmap) {
-                        ret = search_bitmap(block_group, entry, offset, bytes);
+                        ret = search_bitmap(ctl, entry, offset, bytes);
                         if (!ret)
                                 return entry;
                         continue;
@@ -402,23 +1318,28 @@ static struct btrfs_free_space *find_free_space(struct btrfs_block_group_cache
         return NULL;
 }
 
-static void add_new_bitmap(struct btrfs_block_group_cache *block_group,
+static void add_new_bitmap(struct btrfs_free_space_ctl *ctl,
                            struct btrfs_free_space *info, u64 offset)
 {
-        u64 bytes_per_bg = BITS_PER_BITMAP * block_group->sectorsize;
-        int max_bitmaps = (int)div64_u64(block_group->key.offset +
-                                         bytes_per_bg - 1, bytes_per_bg);
-        BUG_ON(block_group->total_bitmaps >= max_bitmaps);
-
-        info->offset = offset_to_bitmap(block_group, offset);
+        info->offset = offset_to_bitmap(ctl, offset);
         info->bytes = 0;
-        link_free_space(block_group, info);
-        block_group->total_bitmaps++;
+        link_free_space(ctl, info);
+        ctl->total_bitmaps++;
 
-        recalculate_thresholds(block_group);
+        ctl->op->recalc_thresholds(ctl);
 }
 
-static noinline int remove_from_bitmap(struct btrfs_block_group_cache *block_group,
+static void free_bitmap(struct btrfs_free_space_ctl *ctl,
+                        struct btrfs_free_space *bitmap_info)
+{
+        unlink_free_space(ctl, bitmap_info);
+        kfree(bitmap_info->bitmap);
+        kmem_cache_free(btrfs_free_space_cachep, bitmap_info);
+        ctl->total_bitmaps--;
+        ctl->op->recalc_thresholds(ctl);
+}
+
+static noinline int remove_from_bitmap(struct btrfs_free_space_ctl *ctl,
                               struct btrfs_free_space *bitmap_info,
                               u64 *offset, u64 *bytes)
 {
@@ -427,8 +1348,7 @@ static noinline int remove_from_bitmap(struct btrfs_block_group_cache *block_gro
         int ret;
 
 again:
-        end = bitmap_info->offset +
-                (u64)(BITS_PER_BITMAP * block_group->sectorsize) - 1;
+        end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit) - 1;
 
         /*
          * XXX - this can go away after a few releases.
@@ -442,29 +1362,23 @@ again:
          */
         search_start = *offset;
         search_bytes = *bytes;
-        ret = search_bitmap(block_group, bitmap_info, &search_start,
-                            &search_bytes);
+        search_bytes = min(search_bytes, end - search_start + 1);
+        ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes);
         BUG_ON(ret < 0 || search_start != *offset);
 
         if (*offset > bitmap_info->offset && *offset + *bytes > end) {
-                bitmap_clear_bits(block_group, bitmap_info, *offset,
-                                  end - *offset + 1);
+                bitmap_clear_bits(ctl, bitmap_info, *offset, end - *offset + 1);
                 *bytes -= end - *offset + 1;
                 *offset = end + 1;
         } else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) {
-                bitmap_clear_bits(block_group, bitmap_info, *offset, *bytes);
+                bitmap_clear_bits(ctl, bitmap_info, *offset, *bytes);
                 *bytes = 0;
         }
 
         if (*bytes) {
                 struct rb_node *next = rb_next(&bitmap_info->offset_index);
-                if (!bitmap_info->bytes) {
-                        unlink_free_space(block_group, bitmap_info);
-                        kfree(bitmap_info->bitmap);
-                        kfree(bitmap_info);
-                        block_group->total_bitmaps--;
-                        recalculate_thresholds(block_group);
-                }
+                if (!bitmap_info->bytes)
+                        free_bitmap(ctl, bitmap_info);
 
                 /*
                  * no entry after this bitmap, but we still have bytes to
@@ -491,38 +1405,59 @@ again:
                  */
                 search_start = *offset;
                 search_bytes = *bytes;
-                ret = search_bitmap(block_group, bitmap_info, &search_start,
+                ret = search_bitmap(ctl, bitmap_info, &search_start,
                                     &search_bytes);
                 if (ret < 0 || search_start != *offset)
                         return -EAGAIN;
 
                 goto again;
-        } else if (!bitmap_info->bytes) {
-                unlink_free_space(block_group, bitmap_info);
-                kfree(bitmap_info->bitmap);
-                kfree(bitmap_info);
-                block_group->total_bitmaps--;
-                recalculate_thresholds(block_group);
-        }
+        } else if (!bitmap_info->bytes)
+                free_bitmap(ctl, bitmap_info);
 
         return 0;
 }
 
-static int insert_into_bitmap(struct btrfs_block_group_cache *block_group,
-                              struct btrfs_free_space *info)
+static u64 add_bytes_to_bitmap(struct btrfs_free_space_ctl *ctl,
+                               struct btrfs_free_space *info, u64 offset,
+                               u64 bytes)
 {
-        struct btrfs_free_space *bitmap_info;
-        int added = 0;
-        u64 bytes, offset, end;
-        int ret;
+        u64 bytes_to_set = 0;
+        u64 end;
+
+        end = info->offset + (u64)(BITS_PER_BITMAP * ctl->unit);
+
+        bytes_to_set = min(end - offset, bytes);
+
+        bitmap_set_bits(ctl, info, offset, bytes_to_set);
+
+        return bytes_to_set;
+
+}
+
+static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
+                      struct btrfs_free_space *info)
+{
+        struct btrfs_block_group_cache *block_group = ctl->private;
 
         /*
          * If we are below the extents threshold then we can add this as an
          * extent, and don't have to deal with the bitmap
          */
-        if (block_group->free_extents < block_group->extents_thresh &&
-            info->bytes > block_group->sectorsize * 4)
-                return 0;
+        if (ctl->free_extents < ctl->extents_thresh) {
+                /*
+                 * If this block group has some small extents we don't want to
+                 * use up all of our free slots in the cache with them, we want
+                 * to reserve them to larger extents, however if we have plent
+                 * of cache left then go ahead an dadd them, no sense in adding
+                 * the overhead of a bitmap if we don't have to.
+                 */
+                if (info->bytes <= block_group->sectorsize * 4) {
+                        if (ctl->free_extents * 2 <= ctl->extents_thresh)
+                                return false;
+                } else {
+                        return false;
+                }
+        }
 
         /*
          * some block groups are so tiny they can't be enveloped by a bitmap, so
@@ -530,35 +1465,85 @@ static int insert_into_bitmap(struct btrfs_block_group_cache *block_group,
          */
         if (BITS_PER_BITMAP * block_group->sectorsize >
             block_group->key.offset)
-                return 0;
+                return false;
+
+        return true;
+}
+
+static struct btrfs_free_space_op free_space_op = {
+        .recalc_thresholds      = recalculate_thresholds,
+        .use_bitmap             = use_bitmap,
+};
+
+static int insert_into_bitmap(struct btrfs_free_space_ctl *ctl,
+                              struct btrfs_free_space *info)
+{
+        struct btrfs_free_space *bitmap_info;
+        struct btrfs_block_group_cache *block_group = NULL;
+        int added = 0;
+        u64 bytes, offset, bytes_added;
+        int ret;
 
         bytes = info->bytes;
         offset = info->offset;
 
+        if (!ctl->op->use_bitmap(ctl, info))
+                return 0;
+
+        if (ctl->op == &free_space_op)
+                block_group = ctl->private;
 again:
-        bitmap_info = tree_search_offset(block_group,
-                                         offset_to_bitmap(block_group, offset),
+        /*
+         * Since we link bitmaps right into the cluster we need to see if we
+         * have a cluster here, and if so and it has our bitmap we need to add
+         * the free space to that bitmap.
+         */
+        if (block_group && !list_empty(&block_group->cluster_list)) {
+                struct btrfs_free_cluster *cluster;
+                struct rb_node *node;
+                struct btrfs_free_space *entry;
+
+                cluster = list_entry(block_group->cluster_list.next,
+                                     struct btrfs_free_cluster,
+                                     block_group_list);
+                spin_lock(&cluster->lock);
+                node = rb_first(&cluster->root);
+                if (!node) {
+                        spin_unlock(&cluster->lock);
+                        goto no_cluster_bitmap;
+                }
+
+                entry = rb_entry(node, struct btrfs_free_space, offset_index);
+                if (!entry->bitmap) {
+                        spin_unlock(&cluster->lock);
+                        goto no_cluster_bitmap;
+                }
+
+                if (entry->offset == offset_to_bitmap(ctl, offset)) {
+                        bytes_added = add_bytes_to_bitmap(ctl, entry,
+                                                          offset, bytes);
+                        bytes -= bytes_added;
+                        offset += bytes_added;
+                }
+                spin_unlock(&cluster->lock);
+                if (!bytes) {
+                        ret = 1;
+                        goto out;
+                }
+        }
+
+no_cluster_bitmap:
+        bitmap_info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
                                          1, 0);
         if (!bitmap_info) {
                 BUG_ON(added);
                 goto new_bitmap;
         }
 
-        end = bitmap_info->offset +
-                (u64)(BITS_PER_BITMAP * block_group->sectorsize);
-
-        if (offset >= bitmap_info->offset && offset + bytes > end) {
-                bitmap_set_bits(block_group, bitmap_info, offset,
-                                end - offset);
-                bytes -= end - offset;
-                offset = end;
-                added = 0;
-        } else if (offset >= bitmap_info->offset && offset + bytes <= end) {
-                bitmap_set_bits(block_group, bitmap_info, offset, bytes);
-                bytes = 0;
-        } else {
-                BUG();
-        }
+        bytes_added = add_bytes_to_bitmap(ctl, bitmap_info, offset, bytes);
+        bytes -= bytes_added;
+        offset += bytes_added;
+        added = 0;
 
         if (!bytes) {
                 ret = 1;
@@ -568,19 +1553,19 @@ again:
 
 new_bitmap:
         if (info && info->bitmap) {
-                add_new_bitmap(block_group, info, offset);
+                add_new_bitmap(ctl, info, offset);
                 added = 1;
                 info = NULL;
                 goto again;
         } else {
-                spin_unlock(&block_group->tree_lock);
+                spin_unlock(&ctl->tree_lock);
 
                 /* no pre-allocated info, allocate a new one */
                 if (!info) {
-                        info = kzalloc(sizeof(struct btrfs_free_space),
-                                       GFP_NOFS);
+                        info = kmem_cache_zalloc(btrfs_free_space_cachep,
+                                                 GFP_NOFS);
                         if (!info) {
-                                spin_lock(&block_group->tree_lock);
+                                spin_lock(&ctl->tree_lock);
                                 ret = -ENOMEM;
                                 goto out;
                         }
@@ -588,7 +1573,7 @@ new_bitmap:
 
                 /* allocate the bitmap */
                 info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
-                spin_lock(&block_group->tree_lock);
+                spin_lock(&ctl->tree_lock);
                 if (!info->bitmap) {
                         ret = -ENOMEM;
                         goto out;
@@ -600,77 +1585,94 @@ out:
         if (info) {
                 if (info->bitmap)
                         kfree(info->bitmap);
-                kfree(info);
+                kmem_cache_free(btrfs_free_space_cachep, info);
         }
 
         return ret;
 }
 
-int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
-                         u64 offset, u64 bytes)
+static bool try_merge_free_space(struct btrfs_free_space_ctl *ctl,
+                          struct btrfs_free_space *info, bool update_stat)
 {
-        struct btrfs_free_space *right_info = NULL;
-        struct btrfs_free_space *left_info = NULL;
-        struct btrfs_free_space *info = NULL;
-        int ret = 0;
-
-        info = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS);
-        if (!info)
-                return -ENOMEM;
-
-        info->offset = offset;
-        info->bytes = bytes;
-
-        spin_lock(&block_group->tree_lock);
+        struct btrfs_free_space *left_info;
+        struct btrfs_free_space *right_info;
+        bool merged = false;
+        u64 offset = info->offset;
+        u64 bytes = info->bytes;
 
         /*
          * first we want to see if there is free space adjacent to the range we
          * are adding, if there is remove that struct and add a new one to
          * cover the entire range
          */
-        right_info = tree_search_offset(block_group, offset + bytes, 0, 0);
+        right_info = tree_search_offset(ctl, offset + bytes, 0, 0);
         if (right_info && rb_prev(&right_info->offset_index))
                 left_info = rb_entry(rb_prev(&right_info->offset_index),
                                      struct btrfs_free_space, offset_index);
         else
-                left_info = tree_search_offset(block_group, offset - 1, 0, 0);
-
-        /*
-         * If there was no extent directly to the left or right of this new
-         * extent then we know we're going to have to allocate a new extent, so
-         * before we do that see if we need to drop this into a bitmap
-         */
-        if ((!left_info || left_info->bitmap) &&
-            (!right_info || right_info->bitmap)) {
-                ret = insert_into_bitmap(block_group, info);
-
-                if (ret < 0) {
-                        goto out;
-                } else if (ret) {
-                        ret = 0;
-                        goto out;
-                }
-        }
+                left_info = tree_search_offset(ctl, offset - 1, 0, 0);
 
         if (right_info && !right_info->bitmap) {
-                unlink_free_space(block_group, right_info);
+                if (update_stat)
+                        unlink_free_space(ctl, right_info);
+                else
+                        __unlink_free_space(ctl, right_info);
                 info->bytes += right_info->bytes;
-                kfree(right_info);
+                kmem_cache_free(btrfs_free_space_cachep, right_info);
+                merged = true;
         }
 
         if (left_info && !left_info->bitmap &&
             left_info->offset + left_info->bytes == offset) {
-                unlink_free_space(block_group, left_info);
+                if (update_stat)
+                        unlink_free_space(ctl, left_info);
+                else
+                        __unlink_free_space(ctl, left_info);
                 info->offset = left_info->offset;
                 info->bytes += left_info->bytes;
-                kfree(left_info);
+                kmem_cache_free(btrfs_free_space_cachep, left_info);
+                merged = true;
         }
 
-        ret = link_free_space(block_group, info);
+        return merged;
+}
+
+int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
+                           u64 offset, u64 bytes)
+{
+        struct btrfs_free_space *info;
+        int ret = 0;
+
+        info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
+        if (!info)
+                return -ENOMEM;
+
+        info->offset = offset;
+        info->bytes = bytes;
+
+        spin_lock(&ctl->tree_lock);
+
+        if (try_merge_free_space(ctl, info, true))
+                goto link;
+
+        /*
+         * There was no extent directly to the left or right of this new
+         * extent then we know we're going to have to allocate a new extent, so
+         * before we do that see if we need to drop this into a bitmap
+         */
+        ret = insert_into_bitmap(ctl, info);
+        if (ret < 0) {
+                goto out;
+        } else if (ret) {
+                ret = 0;
+                goto out;
+        }
+link:
+        ret = link_free_space(ctl, info);
         if (ret)
-                kfree(info);
+                kmem_cache_free(btrfs_free_space_cachep, info);
 out:
-        spin_unlock(&block_group->tree_lock);
+        spin_unlock(&ctl->tree_lock);
 
         if (ret) {
                 printk(KERN_CRIT "btrfs: unable to add free space :%d\n", ret);
@@ -683,21 +1685,21 @@ out:
 int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
                             u64 offset, u64 bytes)
 {
+        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
         struct btrfs_free_space *info;
         struct btrfs_free_space *next_info = NULL;
         int ret = 0;
 
-        spin_lock(&block_group->tree_lock);
+        spin_lock(&ctl->tree_lock);
 
 again:
-        info = tree_search_offset(block_group, offset, 0, 0);
+        info = tree_search_offset(ctl, offset, 0, 0);
         if (!info) {
                 /*
                  * oops didn't find an extent that matched the space we wanted
                  * to remove, look for a bitmap instead
                  */
-                info = tree_search_offset(block_group,
-                                          offset_to_bitmap(block_group, offset),
+                info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
                                           1, 0);
                 if (!info) {
                         WARN_ON(1);
@@ -712,8 +1714,8 @@ again:
                                              offset_index);
 
                 if (next_info->bitmap)
-                        end = next_info->offset + BITS_PER_BITMAP *
-                                block_group->sectorsize - 1;
+                        end = next_info->offset +
+                              BITS_PER_BITMAP * ctl->unit - 1;
                 else
                         end = next_info->offset + next_info->bytes;
 
@@ -733,20 +1735,20 @@ again:
         }
 
         if (info->bytes == bytes) {
-                unlink_free_space(block_group, info);
+                unlink_free_space(ctl, info);
                 if (info->bitmap) {
                         kfree(info->bitmap);
-                        block_group->total_bitmaps--;
+                        ctl->total_bitmaps--;
                 }
-                kfree(info);
+                kmem_cache_free(btrfs_free_space_cachep, info);
                 goto out_lock;
         }
 
         if (!info->bitmap && info->offset == offset) {
-                unlink_free_space(block_group, info);
+                unlink_free_space(ctl, info);
                 info->offset += bytes;
                 info->bytes -= bytes;
-                link_free_space(block_group, info);
+                link_free_space(ctl, info);
                 goto out_lock;
         }
 
@@ -760,13 +1762,13 @@ again:
                  * first unlink the old info and then
                  * insert it again after the hole we're creating
                  */
-                unlink_free_space(block_group, info);
+                unlink_free_space(ctl, info);
                 if (offset + bytes < info->offset + info->bytes) {
                         u64 old_end = info->offset + info->bytes;
 
                         info->offset = offset + bytes;
                         info->bytes = old_end - info->offset;
-                        ret = link_free_space(block_group, info);
+                        ret = link_free_space(ctl, info);
                         WARN_ON(ret);
                         if (ret)
                                 goto out_lock;
@@ -774,9 +1776,9 @@ again:
                         /* the hole we're creating ends at the end
                          * of the info struct, just free the info
                          */
-                        kfree(info);
+                        kmem_cache_free(btrfs_free_space_cachep, info);
                 }
-                spin_unlock(&block_group->tree_lock);
+                spin_unlock(&ctl->tree_lock);
 
                 /* step two, insert a new info struct to cover
                  * anything before the hole
@@ -787,12 +1789,12 @@ again:
                 goto out;
         }
 
-        ret = remove_from_bitmap(block_group, info, &offset, &bytes);
+        ret = remove_from_bitmap(ctl, info, &offset, &bytes);
         if (ret == -EAGAIN)
                 goto again;
         BUG_ON(ret);
 out_lock:
-        spin_unlock(&block_group->tree_lock);
+        spin_unlock(&ctl->tree_lock);
 out:
         return ret;
 }
@@ -800,11 +1802,12 @@ out:
 void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
                            u64 bytes)
 {
+        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
         struct btrfs_free_space *info;
         struct rb_node *n;
         int count = 0;
 
-        for (n = rb_first(&block_group->free_space_offset); n; n = rb_next(n)) {
+        for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
                 info = rb_entry(n, struct btrfs_free_space, offset_index);
                 if (info->bytes >= bytes)
                         count++;
@@ -819,19 +1822,23 @@ void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
                "\n", count);
 }
 
-u64 btrfs_block_group_free_space(struct btrfs_block_group_cache *block_group)
+void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group)
 {
-        struct btrfs_free_space *info;
-        struct rb_node *n;
-        u64 ret = 0;
+        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
 
-        for (n = rb_first(&block_group->free_space_offset); n;
-             n = rb_next(n)) {
-                info = rb_entry(n, struct btrfs_free_space, offset_index);
-                ret += info->bytes;
-        }
+        spin_lock_init(&ctl->tree_lock);
+        ctl->unit = block_group->sectorsize;
+        ctl->start = block_group->key.objectid;
+        ctl->private = block_group;
+        ctl->op = &free_space_op;
 
-        return ret;
+        /*
+         * we only want to have 32k of ram per block group for keeping
+         * track of free space, and if we pass 1/2 of that we want to
+         * start converting things over to using bitmaps
+         */
+        ctl->extents_thresh = ((1024 * 32) / 2) /
+                                sizeof(struct btrfs_free_space);
 }
 
 /*
@@ -845,31 +1852,31 @@ __btrfs_return_cluster_to_free_space(
                              struct btrfs_block_group_cache *block_group,
                              struct btrfs_free_cluster *cluster)
 {
+        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
         struct btrfs_free_space *entry;
         struct rb_node *node;
-        bool bitmap;
 
         spin_lock(&cluster->lock);
         if (cluster->block_group != block_group)
                 goto out;
 
-        bitmap = cluster->points_to_bitmap;
         cluster->block_group = NULL;
         cluster->window_start = 0;
         list_del_init(&cluster->block_group_list);
-        cluster->points_to_bitmap = false;
-
-        if (bitmap)
-                goto out;
 
         node = rb_first(&cluster->root);
         while (node) {
+                bool bitmap;
+
                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
                 node = rb_next(&entry->offset_index);
                 rb_erase(&entry->offset_index, &cluster->root);
-                BUG_ON(entry->bitmap);
-                tree_insert_offset(&block_group->free_space_offset,
-                                   entry->offset, &entry->offset_index, 0);
+
+                bitmap = (entry->bitmap != NULL);
+                if (!bitmap)
+                        try_merge_free_space(ctl, entry, false);
+                tree_insert_offset(&ctl->free_space_offset,
+                                   entry->offset, &entry->offset_index, bitmap);
         }
         cluster->root = RB_ROOT;
 
@@ -879,14 +1886,41 @@ out:
         return 0;
 }
 
-void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
+void __btrfs_remove_free_space_cache_locked(struct btrfs_free_space_ctl *ctl)
 {
         struct btrfs_free_space *info;
         struct rb_node *node;
+
+        while ((node = rb_last(&ctl->free_space_offset)) != NULL) {
+                info = rb_entry(node, struct btrfs_free_space, offset_index);
+                if (!info->bitmap) {
+                        unlink_free_space(ctl, info);
+                        kmem_cache_free(btrfs_free_space_cachep, info);
+                } else {
+                        free_bitmap(ctl, info);
+                }
+                if (need_resched()) {
+                        spin_unlock(&ctl->tree_lock);
+                        cond_resched();
+                        spin_lock(&ctl->tree_lock);
+                }
+        }
+}
+
+void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl)
+{
+        spin_lock(&ctl->tree_lock);
+        __btrfs_remove_free_space_cache_locked(ctl);
+        spin_unlock(&ctl->tree_lock);
+}
+
+void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
+{
+        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
         struct btrfs_free_cluster *cluster;
         struct list_head *head;
 
-        spin_lock(&block_group->tree_lock);
+        spin_lock(&ctl->tree_lock);
         while ((head = block_group->cluster_list.next) !=
                &block_group->cluster_list) {
                 cluster = list_entry(head, struct btrfs_free_cluster,
@@ -895,62 +1929,46 @@ void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
                 WARN_ON(cluster->block_group != block_group);
                 __btrfs_return_cluster_to_free_space(block_group, cluster);
                 if (need_resched()) {
-                        spin_unlock(&block_group->tree_lock);
-                        cond_resched();
-                        spin_lock(&block_group->tree_lock);
-                }
-        }
-
-        while ((node = rb_last(&block_group->free_space_offset)) != NULL) {
-                info = rb_entry(node, struct btrfs_free_space, offset_index);
-                unlink_free_space(block_group, info);
-                if (info->bitmap)
-                        kfree(info->bitmap);
-                kfree(info);
-                if (need_resched()) {
-                        spin_unlock(&block_group->tree_lock);
+                        spin_unlock(&ctl->tree_lock);
                         cond_resched();
-                        spin_lock(&block_group->tree_lock);
+                        spin_lock(&ctl->tree_lock);
                 }
         }
+        __btrfs_remove_free_space_cache_locked(ctl);
+        spin_unlock(&ctl->tree_lock);
 
-        spin_unlock(&block_group->tree_lock);
 }
 
 u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
                                u64 offset, u64 bytes, u64 empty_size)
 {
+        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
         struct btrfs_free_space *entry = NULL;
         u64 bytes_search = bytes + empty_size;
         u64 ret = 0;
 
-        spin_lock(&block_group->tree_lock);
-        entry = find_free_space(block_group, &offset, &bytes_search, 0);
+        spin_lock(&ctl->tree_lock);
+        entry = find_free_space(ctl, &offset, &bytes_search);
         if (!entry)
                 goto out;
 
         ret = offset;
         if (entry->bitmap) {
-                bitmap_clear_bits(block_group, entry, offset, bytes);
-                if (!entry->bytes) {
-                        unlink_free_space(block_group, entry);
-                        kfree(entry->bitmap);
-                        kfree(entry);
-                        block_group->total_bitmaps--;
-                        recalculate_thresholds(block_group);
-                }
+                bitmap_clear_bits(ctl, entry, offset, bytes);
+                if (!entry->bytes)
+                        free_bitmap(ctl, entry);
         } else {
-                unlink_free_space(block_group, entry);
+                unlink_free_space(ctl, entry);
                 entry->offset += bytes;
                 entry->bytes -= bytes;
                 if (!entry->bytes)
-                        kfree(entry);
+                        kmem_cache_free(btrfs_free_space_cachep, entry);
                 else
-                        link_free_space(block_group, entry);
+                        link_free_space(ctl, entry);
         }
 
 out:
-        spin_unlock(&block_group->tree_lock);
+        spin_unlock(&ctl->tree_lock);
 
         return ret;
 }
@@ -967,6 +1985,7 @@ int btrfs_return_cluster_to_free_space(
                                struct btrfs_block_group_cache *block_group,
                                struct btrfs_free_cluster *cluster)
 {
+        struct btrfs_free_space_ctl *ctl;
         int ret;
 
         /* first, get a safe pointer to the block group */
@@ -985,10 +2004,12 @@ int btrfs_return_cluster_to_free_space(
         atomic_inc(&block_group->count);
         spin_unlock(&cluster->lock);
 
+        ctl = block_group->free_space_ctl;
+
         /* now return any extents the cluster had on it */
-        spin_lock(&block_group->tree_lock);
+        spin_lock(&ctl->tree_lock);
         ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
-        spin_unlock(&block_group->tree_lock);
+        spin_unlock(&ctl->tree_lock);
 
         /* finally drop our ref */
         btrfs_put_block_group(block_group);
@@ -997,48 +2018,24 @@ int btrfs_return_cluster_to_free_space(
 
 static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
                                    struct btrfs_free_cluster *cluster,
+                                   struct btrfs_free_space *entry,
                                    u64 bytes, u64 min_start)
 {
-        struct btrfs_free_space *entry;
+        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
         int err;
         u64 search_start = cluster->window_start;
         u64 search_bytes = bytes;
         u64 ret = 0;
 
-        spin_lock(&block_group->tree_lock);
-        spin_lock(&cluster->lock);
-
-        if (!cluster->points_to_bitmap)
-                goto out;
-
-        if (cluster->block_group != block_group)
-                goto out;
-
-        /*
-         * search_start is the beginning of the bitmap, but at some point it may
-         * be a good idea to point to the actual start of the free area in the
-         * bitmap, so do the offset_to_bitmap trick anyway, and set bitmap_only
-         * to 1 to make sure we get the bitmap entry
-         */
-        entry = tree_search_offset(block_group,
-                                   offset_to_bitmap(block_group, search_start),
-                                   1, 0);
-        if (!entry || !entry->bitmap)
-                goto out;
-
         search_start = min_start;
         search_bytes = bytes;
 
-        err = search_bitmap(block_group, entry, &search_start,
-                            &search_bytes);
+        err = search_bitmap(ctl, entry, &search_start, &search_bytes);
         if (err)
-                goto out;
+                return 0;
 
         ret = search_start;
-        bitmap_clear_bits(block_group, entry, ret, bytes);
-out:
-        spin_unlock(&cluster->lock);
-        spin_unlock(&block_group->tree_lock);
+        bitmap_clear_bits(ctl, entry, ret, bytes);
 
         return ret;
 }
@@ -1052,14 +2049,11 @@ 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_ctl *ctl = block_group->free_space_ctl;
         struct btrfs_free_space *entry = NULL;
         struct rb_node *node;
         u64 ret = 0;
 
-        if (cluster->points_to_bitmap)
-                return btrfs_alloc_from_bitmap(block_group, cluster, bytes,
-                                               min_start);
-
         spin_lock(&cluster->lock);
         if (bytes > cluster->max_size)
                 goto out;
@@ -1072,11 +2066,9 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
                 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;
-
+                if (entry->bytes < bytes ||
+                    (!entry->bitmap && entry->offset < min_start)) {
                         node = rb_next(&entry->offset_index);
                         if (!node)
                                 break;
@@ -1084,20 +2076,52 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
                                          offset_index);
                         continue;
                 }
-                ret = entry->offset;
 
-                entry->offset += bytes;
-                entry->bytes -= bytes;
+                if (entry->bitmap) {
+                        ret = btrfs_alloc_from_bitmap(block_group,
+                                                      cluster, entry, bytes,
+                                                      min_start);
+                        if (ret == 0) {
+                                node = rb_next(&entry->offset_index);
+                                if (!node)
+                                        break;
+                                entry = rb_entry(node, struct btrfs_free_space,
+                                                 offset_index);
+                                continue;
+                        }
+                } else {
 
-                if (entry->bytes == 0) {
-                        rb_erase(&entry->offset_index, &cluster->root);
-                        kfree(entry);
+                        ret = entry->offset;
+
+                        entry->offset += bytes;
+                        entry->bytes -= bytes;
                 }
+
+                if (entry->bytes == 0)
+                        rb_erase(&entry->offset_index, &cluster->root);
                 break;
         }
 out:
         spin_unlock(&cluster->lock);
 
+        if (!ret)
+                return 0;
+
+        spin_lock(&ctl->tree_lock);
+
+        ctl->free_space -= bytes;
+        if (entry->bytes == 0) {
+                ctl->free_extents--;
+                if (entry->bitmap) {
+                        kfree(entry->bitmap);
+                        ctl->total_bitmaps--;
+                        ctl->op->recalc_thresholds(ctl);
+                }
+                kmem_cache_free(btrfs_free_space_cachep, entry);
+        }
+
+        spin_unlock(&ctl->tree_lock);
+
         return ret;
 }
 
@@ -1106,6 +2130,7 @@ static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
                                 struct btrfs_free_cluster *cluster,
                                 u64 offset, u64 bytes, u64 min_bytes)
 {
+        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
         unsigned long next_zero;
         unsigned long i;
         unsigned long search_bits;
@@ -1113,12 +2138,13 @@ static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
         unsigned long found_bits;
         unsigned long start = 0;
         unsigned long total_found = 0;
+        int ret;
         bool found = false;
 
         i = offset_to_bit(entry->offset, block_group->sectorsize,
                           max_t(u64, offset, entry->offset));
-        search_bits = bytes_to_bits(min_bytes, block_group->sectorsize);
-        total_bits = bytes_to_bits(bytes, block_group->sectorsize);
+        search_bits = bytes_to_bits(bytes, block_group->sectorsize);
+        total_bits = bytes_to_bits(min_bytes, block_group->sectorsize);
 
 again:
         found_bits = 0;
@@ -1135,7 +2161,7 @@ again:
         }
 
         if (!found_bits)
-                return -1;
+                return -ENOSPC;
 
         if (!found) {
                 start = i;
@@ -1159,131 +2185,67 @@ again:
 
         cluster->window_start = start * block_group->sectorsize +
                 entry->offset;
-        cluster->points_to_bitmap = true;
+        rb_erase(&entry->offset_index, &ctl->free_space_offset);
+        ret = tree_insert_offset(&cluster->root, entry->offset,
+                                 &entry->offset_index, 1);
+        BUG_ON(ret);
 
         return 0;
 }
 
 /*
- * 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
+ * This searches the block group for just extents to fill the cluster with.
  */
-int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
-                             struct btrfs_root *root,
-                             struct btrfs_block_group_cache *block_group,
-                             struct btrfs_free_cluster *cluster,
-                             u64 offset, u64 bytes, u64 empty_size)
+static noinline int
+setup_cluster_no_bitmap(struct btrfs_block_group_cache *block_group,
+                        struct btrfs_free_cluster *cluster,
+                        struct list_head *bitmaps, u64 offset, u64 bytes,
+                        u64 min_bytes)
 {
+        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
+        struct btrfs_free_space *first = NULL;
         struct btrfs_free_space *entry = NULL;
+        struct btrfs_free_space *prev = NULL;
+        struct btrfs_free_space *last;
         struct rb_node *node;
-        struct btrfs_free_space *next;
-        struct btrfs_free_space *last = NULL;
-        u64 min_bytes;
         u64 window_start;
         u64 window_free;
-        u64 max_extent = 0;
-        bool found_bitmap = false;
-        int ret;
+        u64 max_extent;
+        u64 max_gap = 128 * 1024;
 
-        /* for metadata, allow allocates with more holes */
-        if (btrfs_test_opt(root, SSD_SPREAD)) {
-                min_bytes = bytes + empty_size;
-        } else 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:
-        entry = tree_search_offset(block_group, offset, found_bitmap, 1);
-        if (!entry) {
-                ret = -ENOSPC;
-                goto out;
-        }
+        entry = tree_search_offset(ctl, offset, 0, 1);
+        if (!entry)
+                return -ENOSPC;
 
         /*
-         * If found_bitmap is true, we exhausted our search for extent entries,
-         * and we just want to search all of the bitmaps that we can find, and
-         * ignore any extent entries we find.
+         * We don't want bitmaps, so just move along until we find a normal
+         * extent entry.
          */
-        while (entry->bitmap || found_bitmap ||
-               (!entry->bitmap && entry->bytes < min_bytes)) {
-                struct rb_node *node = rb_next(&entry->offset_index);
-
-                if (entry->bitmap && entry->bytes > bytes + empty_size) {
-                        ret = btrfs_bitmap_cluster(block_group, entry, cluster,
-                                                   offset, bytes + empty_size,
-                                                   min_bytes);
-                        if (!ret)
-                                goto got_it;
-                }
-
-                if (!node) {
-                        ret = -ENOSPC;
-                        goto out;
-                }
+        while (entry->bitmap) {
+                if (list_empty(&entry->list))
+                        list_add_tail(&entry->list, bitmaps);
+                node = rb_next(&entry->offset_index);
+                if (!node)
+                        return -ENOSPC;
                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
         }
 
-        /*
-         * We already searched all the extent entries from the passed in offset
-         * to the end and didn't find enough space for the cluster, and we also
-         * didn't find any bitmaps that met our criteria, just go ahead and exit
-         */
-        if (found_bitmap) {
-                ret = -ENOSPC;
-                goto out;
-        }
-
-        cluster->points_to_bitmap = false;
         window_start = entry->offset;
         window_free = entry->bytes;
-        last = entry;
         max_extent = entry->bytes;
+        first = entry;
+        last = entry;
+        prev = entry;
 
-        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) {
-                        if (found_bitmap)
-                                goto again;
-                        ret = -ENOSPC;
-                        goto out;
-                }
-                next = rb_entry(node, struct btrfs_free_space, offset_index);
+        while (window_free <= min_bytes) {
+                node = rb_next(&entry->offset_index);
+                if (!node)
+                        return -ENOSPC;
+                entry = rb_entry(node, struct btrfs_free_space, offset_index);
 
-                /*
-                 * we found a bitmap, so if this search doesn't result in a
-                 * cluster, we know to go and search again for the bitmaps and
-                 * start looking for space there
-                 */
-                if (next->bitmap) {
-                        if (!found_bitmap)
-                                offset = next->offset;
-                        found_bitmap = true;
-                        last = next;
+                if (entry->bitmap) {
+                        if (list_empty(&entry->list))
+                                list_add_tail(&entry->list, bitmaps);
                         continue;
                 }
 
@@ -1291,60 +2253,190 @@ again:
                  * we haven't filled the empty size and the window is
                  * very large.  reset and try again
                  */
-                if (next->offset - (last->offset + last->bytes) > 128 * 1024 ||
-                    next->offset - window_start > (bytes + empty_size) * 2) {
-                        entry = next;
+                if (entry->offset - (prev->offset + prev->bytes) > max_gap ||
+                    entry->offset - window_start > (min_bytes * 2)) {
+                        first = entry;
                         window_start = entry->offset;
                         window_free = entry->bytes;
                         last = entry;
                         max_extent = entry->bytes;
                 } else {
-                        last = next;
-                        window_free += next->bytes;
+                        last = entry;
+                        window_free += entry->bytes;
                         if (entry->bytes > max_extent)
                                 max_extent = entry->bytes;
                 }
+                prev = entry;
         }
 
-        cluster->window_start = entry->offset;
+        cluster->window_start = first->offset;
+
+        node = &first->offset_index;
 
         /*
          * 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) {
+        do {
+                int ret;
+
+                entry = rb_entry(node, struct btrfs_free_space, offset_index);
                 node = rb_next(&entry->offset_index);
-                if (entry->bitmap && node) {
-                        entry = rb_entry(node, struct btrfs_free_space,
-                                         offset_index);
+                if (entry->bitmap)
                         continue;
-                } else if (entry->bitmap && !node) {
-                        break;
-                }
 
-                rb_erase(&entry->offset_index, &block_group->free_space_offset);
+                rb_erase(&entry->offset_index, &ctl->free_space_offset);
                 ret = tree_insert_offset(&cluster->root, entry->offset,
                                          &entry->offset_index, 0);
                 BUG_ON(ret);
+        } while (node && entry != last);
 
-                if (!node || entry == last)
-                        break;
+        cluster->max_size = max_extent;
 
+        return 0;
+}
+
+/*
+ * This specifically looks for bitmaps that may work in the cluster, we assume
+ * that we have already failed to find extents that will work.
+ */
+static noinline int
+setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
+                     struct btrfs_free_cluster *cluster,
+                     struct list_head *bitmaps, u64 offset, u64 bytes,
+                     u64 min_bytes)
+{
+        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
+        struct btrfs_free_space *entry;
+        struct rb_node *node;
+        int ret = -ENOSPC;
+
+        if (ctl->total_bitmaps == 0)
+                return -ENOSPC;
+
+        /*
+         * First check our cached list of bitmaps and see if there is an entry
+         * here that will work.
+         */
+        list_for_each_entry(entry, bitmaps, list) {
+                if (entry->bytes < min_bytes)
+                        continue;
+                ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
+                                           bytes, min_bytes);
+                if (!ret)
+                        return 0;
+        }
+
+        /*
+         * If we do have entries on our list and we are here then we didn't find
+         * anything, so go ahead and get the next entry after the last entry in
+         * this list and start the search from there.
+         */
+        if (!list_empty(bitmaps)) {
+                entry = list_entry(bitmaps->prev, struct btrfs_free_space,
+                                   list);
+                node = rb_next(&entry->offset_index);
+                if (!node)
+                        return -ENOSPC;
                 entry = rb_entry(node, struct btrfs_free_space, offset_index);
+                goto search;
         }
 
-        cluster->max_size = max_extent;
-got_it:
-        ret = 0;
-        atomic_inc(&block_group->count);
-        list_add_tail(&cluster->block_group_list, &block_group->cluster_list);
-        cluster->block_group = block_group;
+        entry = tree_search_offset(ctl, offset_to_bitmap(ctl, offset), 0, 1);
+        if (!entry)
+                return -ENOSPC;
+
+search:
+        node = &entry->offset_index;
+        do {
+                entry = rb_entry(node, struct btrfs_free_space, offset_index);
+                node = rb_next(&entry->offset_index);
+                if (!entry->bitmap)
+                        continue;
+                if (entry->bytes < min_bytes)
+                        continue;
+                ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
+                                           bytes, min_bytes);
+        } while (ret && node);
+
+        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_root *root,
+                             struct btrfs_block_group_cache *block_group,
+                             struct btrfs_free_cluster *cluster,
+                             u64 offset, u64 bytes, u64 empty_size)
+{
+        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
+        struct list_head bitmaps;
+        struct btrfs_free_space *entry, *tmp;
+        u64 min_bytes;
+        int ret;
+
+        /* for metadata, allow allocates with more holes */
+        if (btrfs_test_opt(root, SSD_SPREAD)) {
+                min_bytes = bytes + empty_size;
+        } else 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(&ctl->tree_lock);
+
+        /*
+         * If we know we don't have enough space to make a cluster don't even
+         * bother doing all the work to try and find one.
+         */
+        if (ctl->free_space < min_bytes) {
+                spin_unlock(&ctl->tree_lock);
+                return -ENOSPC;
+        }
+
+        spin_lock(&cluster->lock);
+
+        /* someone already found a cluster, hooray */
+        if (cluster->block_group) {
+                ret = 0;
+                goto out;
+        }
+
+        INIT_LIST_HEAD(&bitmaps);
+        ret = setup_cluster_no_bitmap(block_group, cluster, &bitmaps, offset,
+                                      bytes, min_bytes);
+        if (ret)
+                ret = setup_cluster_bitmap(block_group, cluster, &bitmaps,
+                                           offset, bytes, min_bytes);
+
+        /* Clear our temporary list */
+        list_for_each_entry_safe(entry, tmp, &bitmaps, list)
+                list_del_init(&entry->list);
+
+        if (!ret) {
+                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);
+        spin_unlock(&ctl->tree_lock);
 
         return ret;
 }
@@ -1358,8 +2450,244 @@ void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
         spin_lock_init(&cluster->refill_lock);
         cluster->root = RB_ROOT;
         cluster->max_size = 0;
-        cluster->points_to_bitmap = false;
         INIT_LIST_HEAD(&cluster->block_group_list);
         cluster->block_group = NULL;
 }
 
+int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
+                           u64 *trimmed, u64 start, u64 end, u64 minlen)
+{
+        struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
+        struct btrfs_free_space *entry = NULL;
+        struct btrfs_fs_info *fs_info = block_group->fs_info;
+        u64 bytes = 0;
+        u64 actually_trimmed;
+        int ret = 0;
+
+        *trimmed = 0;
+
+        while (start < end) {
+                spin_lock(&ctl->tree_lock);
+
+                if (ctl->free_space < minlen) {
+                        spin_unlock(&ctl->tree_lock);
+                        break;
+                }
+
+                entry = tree_search_offset(ctl, start, 0, 1);
+                if (!entry)
+                        entry = tree_search_offset(ctl,
+                                                   offset_to_bitmap(ctl, start),
+                                                   1, 1);
+
+                if (!entry || entry->offset >= end) {
+                        spin_unlock(&ctl->tree_lock);
+                        break;
+                }
+
+                if (entry->bitmap) {
+                        ret = search_bitmap(ctl, entry, &start, &bytes);
+                        if (!ret) {
+                                if (start >= end) {
+                                        spin_unlock(&ctl->tree_lock);
+                                        break;
+                                }
+                                bytes = min(bytes, end - start);
+                                bitmap_clear_bits(ctl, entry, start, bytes);
+                                if (entry->bytes == 0)
+                                        free_bitmap(ctl, entry);
+                        } else {
+                                start = entry->offset + BITS_PER_BITMAP *
+                                        block_group->sectorsize;
+                                spin_unlock(&ctl->tree_lock);
+                                ret = 0;
+                                continue;
+                        }
+                } else {
+                        start = entry->offset;
+                        bytes = min(entry->bytes, end - start);
+                        unlink_free_space(ctl, entry);
+                        kmem_cache_free(btrfs_free_space_cachep, entry);
+                }
+
+                spin_unlock(&ctl->tree_lock);
+
+                if (bytes >= minlen) {
+                        int update_ret;
+                        update_ret = btrfs_update_reserved_bytes(block_group,
+                                                                 bytes, 1, 1);
+
+                        ret = btrfs_error_discard_extent(fs_info->extent_root,
+                                                         start,
+                                                         bytes,
+                                                         &actually_trimmed);
+
+                        btrfs_add_free_space(block_group, start, bytes);
+                        if (!update_ret)
+                                btrfs_update_reserved_bytes(block_group,
+                                                            bytes, 0, 1);
+
+                        if (ret)
+                                break;
+                        *trimmed += actually_trimmed;
+                }
+                start += bytes;
+                bytes = 0;
+
+                if (fatal_signal_pending(current)) {
+                        ret = -ERESTARTSYS;
+                        break;
+                }
+
+                cond_resched();
+        }
+
+        return ret;
+}
+
+/*
+ * Find the left-most item in the cache tree, and then return the
+ * smallest inode number in the item.
+ *
+ * Note: the returned inode number may not be the smallest one in
+ * the tree, if the left-most item is a bitmap.
+ */
+u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root)
+{
+        struct btrfs_free_space_ctl *ctl = fs_root->free_ino_ctl;
+        struct btrfs_free_space *entry = NULL;
+        u64 ino = 0;
+
+        spin_lock(&ctl->tree_lock);
+
+        if (RB_EMPTY_ROOT(&ctl->free_space_offset))
+                goto out;
+
+        entry = rb_entry(rb_first(&ctl->free_space_offset),
+                         struct btrfs_free_space, offset_index);
+
+        if (!entry->bitmap) {
+                ino = entry->offset;
+
+                unlink_free_space(ctl, entry);
+                entry->offset++;
+                entry->bytes--;
+                if (!entry->bytes)
+                        kmem_cache_free(btrfs_free_space_cachep, entry);
+                else
+                        link_free_space(ctl, entry);
+        } else {
+                u64 offset = 0;
+                u64 count = 1;
+                int ret;
+
+                ret = search_bitmap(ctl, entry, &offset, &count);
+                BUG_ON(ret);
+
+                ino = offset;
+                bitmap_clear_bits(ctl, entry, offset, 1);
+                if (entry->bytes == 0)
+                        free_bitmap(ctl, entry);
+        }
+out:
+        spin_unlock(&ctl->tree_lock);
+
+        return ino;
+}
+
+struct inode *lookup_free_ino_inode(struct btrfs_root *root,
+                                    struct btrfs_path *path)
+{
+        struct inode *inode = NULL;
+
+        spin_lock(&root->cache_lock);
+        if (root->cache_inode)
+                inode = igrab(root->cache_inode);
+        spin_unlock(&root->cache_lock);
+        if (inode)
+                return inode;
+
+        inode = __lookup_free_space_inode(root, path, 0);
+        if (IS_ERR(inode))
+                return inode;
+
+        spin_lock(&root->cache_lock);
+        if (!btrfs_fs_closing(root->fs_info))
+                root->cache_inode = igrab(inode);
+        spin_unlock(&root->cache_lock);
+
+        return inode;
+}
+
+int create_free_ino_inode(struct btrfs_root *root,
+                          struct btrfs_trans_handle *trans,
+                          struct btrfs_path *path)
+{
+        return __create_free_space_inode(root, trans, path,
+                                         BTRFS_FREE_INO_OBJECTID, 0);
+}
+
+int load_free_ino_cache(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
+{
+        struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
+        struct btrfs_path *path;
+        struct inode *inode;
+        int ret = 0;
+        u64 root_gen = btrfs_root_generation(&root->root_item);
+
+        if (!btrfs_test_opt(root, INODE_MAP_CACHE))
+                return 0;
+
+        /*
+         * If we're unmounting then just return, since this does a search on the
+         * normal root and not the commit root and we could deadlock.
+         */
+        if (btrfs_fs_closing(fs_info))
+                return 0;
+
+        path = btrfs_alloc_path();
+        if (!path)
+                return 0;
+
+        inode = lookup_free_ino_inode(root, path);
+        if (IS_ERR(inode))
+                goto out;
+
+        if (root_gen != BTRFS_I(inode)->generation)
+                goto out_put;
+
+        ret = __load_free_space_cache(root, inode, ctl, path, 0);
+
+        if (ret < 0)
+                printk(KERN_ERR "btrfs: failed to load free ino cache for "
+                       "root %llu\n", root->root_key.objectid);
+out_put:
+        iput(inode);
+out:
+        btrfs_free_path(path);
+        return ret;
+}
+
+int btrfs_write_out_ino_cache(struct btrfs_root *root,
+                              struct btrfs_trans_handle *trans,
+                              struct btrfs_path *path)
+{
+        struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
+        struct inode *inode;
+        int ret;
+
+        if (!btrfs_test_opt(root, INODE_MAP_CACHE))
+                return 0;
+
+        inode = lookup_free_ino_inode(root, path);
+        if (IS_ERR(inode))
+                return 0;
+
+        ret = __btrfs_write_out_cache(root, inode, ctl, NULL, trans, path, 0);
+        if (ret < 0)
+                printk(KERN_ERR "btrfs: failed to write free ino cache "
+                       "for root %llu\n", root->root_key.objectid);
+
+        iput(inode);
+        return ret;
+}