text: /*
   * Copyright (C) 2008 Red Hat.  All rights reserved.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License v2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public
   * License along with this program; if not, write to the
   * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   * Boston, MA 021110-1307, USA.
   */
  
  #include <linux/pagemap.h>
  #include <linux/sched.h>
  #include <linux/sched/signal.h>
  #include <linux/slab.h>
  #include <linux/math64.h>
  #include <linux/ratelimit.h>
  #include "ctree.h"
  #include "free-space-cache.h"
  #include "transaction.h"
  #include "disk-io.h"
  #include "extent_io.h"
  #include "inode-map.h"
  #include "volumes.h"
  
  #define BITS_PER_BITMAP		(PAGE_SIZE * 8UL)
  #define MAX_CACHE_BYTES_PER_GIG	SZ_32K
  
  struct btrfs_trim_range {
  	u64 start;
  	u64 bytes;
  	struct list_head list;
  };
  
  static int link_free_space(struct btrfs_free_space_ctl *ctl,
  			   struct btrfs_free_space *info);
  static void unlink_free_space(struct btrfs_free_space_ctl *ctl,
  			      struct btrfs_free_space *info);
  static int btrfs_wait_cache_io_root(struct btrfs_root *root,
  			     struct btrfs_trans_handle *trans,
  			     struct btrfs_io_ctl *io_ctl,
  			     struct btrfs_path *path);
  
  static struct inode *__lookup_free_space_inode(struct btrfs_root *root,
  					       struct btrfs_path *path,
  					       u64 offset)
  {
  	struct btrfs_fs_info *fs_info = root->fs_info;
  	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(fs_info->sb, &location, root, NULL);
  	if (IS_ERR(inode))
  		return inode;
  	if (is_bad_inode(inode)) {
  		iput(inode);
  		return ERR_PTR(-ENOENT);
  	}
  
  	mapping_set_gfp_mask(inode->i_mapping,
  			mapping_gfp_constraint(inode->i_mapping,
  			~(__GFP_FS | __GFP_HIGHMEM)));
  
  	return inode;
  }
  
  struct inode *lookup_free_space_inode(struct btrfs_fs_info *fs_info,
  				      struct btrfs_block_group_cache
  				      *block_group, struct btrfs_path *path)
  {
  	struct inode *inode = NULL;
  	u32 flags = BTRFS_INODE_NODATASUM | BTRFS_INODE_NODATACOW;
  
  	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(fs_info->tree_root, path,
  					  block_group->key.objectid);
  	if (IS_ERR(inode))
  		return inode;
  
  	spin_lock(&block_group->lock);
  	if (!((BTRFS_I(inode)->flags & flags) == flags)) {
  		btrfs_info(fs_info, "Old style space inode found, converting.");
  		BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM |
  			BTRFS_INODE_NODATACOW;
  		block_group->disk_cache_state = BTRFS_DC_CLEAR;
  	}
  
  	if (!block_group->iref) {
  		block_group->inode = igrab(inode);
  		block_group->iref = 1;
  	}
  	spin_unlock(&block_group->lock);
  
  	return inode;
  }
  
  static 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;
  	u64 flags = BTRFS_INODE_NOCOMPRESS | BTRFS_INODE_PREALLOC;
  	int ret;
  
  	ret = btrfs_insert_empty_inode(trans, root, path, ino);
  	if (ret)
  		return ret;
  
  	/* We inline crc's for the free disk space cache */
  	if (ino != BTRFS_FREE_INO_OBJECTID)
  		flags |= BTRFS_INODE_NODATASUM | BTRFS_INODE_NODATACOW;
  
  	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]);
  	memzero_extent_buffer(leaf, (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, flags);
  	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);
  	memzero_extent_buffer(leaf, (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_fs_info *fs_info,
  			    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(fs_info->tree_root, &ino);
  	if (ret < 0)
  		return ret;
  
  	return __create_free_space_inode(fs_info->tree_root, trans, path, ino,
  					 block_group->key.objectid);
  }
  
  int btrfs_check_trunc_cache_free_space(struct btrfs_fs_info *fs_info,
  				       struct btrfs_block_rsv *rsv)
  {
  	u64 needed_bytes;
  	int ret;
  
  	/* 1 for slack space, 1 for updating the inode */
  	needed_bytes = btrfs_calc_trunc_metadata_size(fs_info, 1) +
  		btrfs_calc_trans_metadata_size(fs_info, 1);
  
  	spin_lock(&rsv->lock);
  	if (rsv->reserved < needed_bytes)
  		ret = -ENOSPC;
  	else
  		ret = 0;
  	spin_unlock(&rsv->lock);
  	return ret;
  }
  
  int btrfs_truncate_free_space_cache(struct btrfs_trans_handle *trans,
  				    struct btrfs_block_group_cache *block_group,
  				    struct inode *inode)
  {
  	struct btrfs_root *root = BTRFS_I(inode)->root;
  	int ret = 0;
  	bool locked = false;
  
  	if (block_group) {
  		struct btrfs_path *path = btrfs_alloc_path();
  
  		if (!path) {
  			ret = -ENOMEM;
  			goto fail;
  		}
  		locked = true;
  		mutex_lock(&trans->transaction->cache_write_mutex);
  		if (!list_empty(&block_group->io_list)) {
  			list_del_init(&block_group->io_list);
  
  			btrfs_wait_cache_io(trans, block_group, path);
  			btrfs_put_block_group(block_group);
  		}
  
  		/*
  		 * now that we've truncated the cache away, its no longer
  		 * setup or written
  		 */
  		spin_lock(&block_group->lock);
  		block_group->disk_cache_state = BTRFS_DC_CLEAR;
  		spin_unlock(&block_group->lock);
  		btrfs_free_path(path);
  	}
  
  	btrfs_i_size_write(BTRFS_I(inode), 0);
  	truncate_pagecache(inode, 0);
  
  	/*
  	 * We don't need an orphan item because truncating the free space cache
  	 * will never be split across transactions.
  	 * We don't need to check for -EAGAIN because we're a free space
  	 * cache inode
  	 */
  	ret = btrfs_truncate_inode_items(trans, root, inode,
  					 0, BTRFS_EXTENT_DATA_KEY);
  	if (ret)
  		goto fail;
  
  	ret = btrfs_update_inode(trans, root, inode);
  
  fail:
  	if (locked)
  		mutex_unlock(&trans->transaction->cache_write_mutex);
  	if (ret)
  		btrfs_abort_transaction(trans, ret);
  
  	return ret;
  }
  
  static void readahead_cache(struct inode *inode)
  {
  	struct file_ra_state *ra;
  	unsigned long last_index;
  
  	ra = kzalloc(sizeof(*ra), GFP_NOFS);
  	if (!ra)
  		return;
  
  	file_ra_state_init(ra, inode->i_mapping);
  	last_index = (i_size_read(inode) - 1) >> PAGE_SHIFT;
  
  	page_cache_sync_readahead(inode->i_mapping, ra, NULL, 0, last_index);
  
  	kfree(ra);
  }
  
  static int io_ctl_init(struct btrfs_io_ctl *io_ctl, struct inode *inode,
  		       int write)
  {
  	int num_pages;
  	int check_crcs = 0;
  
  	num_pages = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
  
  	if (btrfs_ino(BTRFS_I(inode)) != BTRFS_FREE_INO_OBJECTID)
  		check_crcs = 1;
  
  	/* Make sure we can fit our crcs into the first page */
  	if (write && check_crcs &&
  	    (num_pages * sizeof(u32)) >= PAGE_SIZE)
  		return -ENOSPC;
  
  	memset(io_ctl, 0, sizeof(struct btrfs_io_ctl));
  
  	io_ctl->pages = kcalloc(num_pages, sizeof(struct page *), GFP_NOFS);
  	if (!io_ctl->pages)
  		return -ENOMEM;
  
  	io_ctl->num_pages = num_pages;
  	io_ctl->fs_info = btrfs_sb(inode->i_sb);
  	io_ctl->check_crcs = check_crcs;
  	io_ctl->inode = inode;
  
  	return 0;
  }
  
  static void io_ctl_free(struct btrfs_io_ctl *io_ctl)
  {
  	kfree(io_ctl->pages);
  	io_ctl->pages = NULL;
  }
  
  static void io_ctl_unmap_page(struct btrfs_io_ctl *io_ctl)
  {
  	if (io_ctl->cur) {
  		io_ctl->cur = NULL;
  		io_ctl->orig = NULL;
  	}
  }
  
  static void io_ctl_map_page(struct btrfs_io_ctl *io_ctl, int clear)
  {
  	ASSERT(io_ctl->index < io_ctl->num_pages);
  	io_ctl->page = io_ctl->pages[io_ctl->index++];
  	io_ctl->cur = page_address(io_ctl->page);
  	io_ctl->orig = io_ctl->cur;
  	io_ctl->size = PAGE_SIZE;
  	if (clear)
  		clear_page(io_ctl->cur);
  }
  
  static void io_ctl_drop_pages(struct btrfs_io_ctl *io_ctl)
  {
  	int i;
  
  	io_ctl_unmap_page(io_ctl);
  
  	for (i = 0; i < io_ctl->num_pages; i++) {
  		if (io_ctl->pages[i]) {
  			ClearPageChecked(io_ctl->pages[i]);
  			unlock_page(io_ctl->pages[i]);
  			put_page(io_ctl->pages[i]);
  		}
  	}
  }
  
  static int io_ctl_prepare_pages(struct btrfs_io_ctl *io_ctl, struct inode *inode,
  				int uptodate)
  {
  	struct page *page;
  	gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
  	int i;
  
  	for (i = 0; i < io_ctl->num_pages; i++) {
  		page = find_or_create_page(inode->i_mapping, i, mask);
  		if (!page) {
  			io_ctl_drop_pages(io_ctl);
  			return -ENOMEM;
  		}
  		io_ctl->pages[i] = page;
  		if (uptodate && !PageUptodate(page)) {
  			btrfs_readpage(NULL, page);
  			lock_page(page);
  			if (!PageUptodate(page)) {
  				btrfs_err(BTRFS_I(inode)->root->fs_info,
  					   "error reading free space cache");
  				io_ctl_drop_pages(io_ctl);
  				return -EIO;
  			}
  		}
  	}
  
  	for (i = 0; i < io_ctl->num_pages; i++) {
  		clear_page_dirty_for_io(io_ctl->pages[i]);
  		set_page_extent_mapped(io_ctl->pages[i]);
  	}
  
  	return 0;
  }
  
  static void io_ctl_set_generation(struct btrfs_io_ctl *io_ctl, u64 generation)
  {
  	__le64 *val;
  
  	io_ctl_map_page(io_ctl, 1);
  
  	/*
  	 * Skip the csum areas.  If we don't check crcs then we just have a
  	 * 64bit chunk at the front of the first page.
  	 */
  	if (io_ctl->check_crcs) {
  		io_ctl->cur += (sizeof(u32) * io_ctl->num_pages);
  		io_ctl->size -= sizeof(u64) + (sizeof(u32) * io_ctl->num_pages);
  	} else {
  		io_ctl->cur += sizeof(u64);
  		io_ctl->size -= sizeof(u64) * 2;
  	}
  
  	val = io_ctl->cur;
  	*val = cpu_to_le64(generation);
  	io_ctl->cur += sizeof(u64);
  }
  
  static int io_ctl_check_generation(struct btrfs_io_ctl *io_ctl, u64 generation)
  {
  	__le64 *gen;
  
  	/*
  	 * Skip the crc area.  If we don't check crcs then we just have a 64bit
  	 * chunk at the front of the first page.
  	 */
  	if (io_ctl->check_crcs) {
  		io_ctl->cur += sizeof(u32) * io_ctl->num_pages;
  		io_ctl->size -= sizeof(u64) +
  			(sizeof(u32) * io_ctl->num_pages);
  	} else {
  		io_ctl->cur += sizeof(u64);
  		io_ctl->size -= sizeof(u64) * 2;
  	}
  
  	gen = io_ctl->cur;
  	if (le64_to_cpu(*gen) != generation) {
  		btrfs_err_rl(io_ctl->fs_info,
  			"space cache generation (%llu) does not match inode (%llu)",
  				*gen, generation);
  		io_ctl_unmap_page(io_ctl);
  		return -EIO;
  	}
  	io_ctl->cur += sizeof(u64);
  	return 0;
  }
  
  static void io_ctl_set_crc(struct btrfs_io_ctl *io_ctl, int index)
  {
  	u32 *tmp;
  	u32 crc = ~(u32)0;
  	unsigned offset = 0;
  
  	if (!io_ctl->check_crcs) {
  		io_ctl_unmap_page(io_ctl);
  		return;
  	}
  
  	if (index == 0)
  		offset = sizeof(u32) * io_ctl->num_pages;
  
  	crc = btrfs_csum_data(io_ctl->orig + offset, crc,
  			      PAGE_SIZE - offset);
  	btrfs_csum_final(crc, (u8 *)&crc);
  	io_ctl_unmap_page(io_ctl);
  	tmp = page_address(io_ctl->pages[0]);
  	tmp += index;
  	*tmp = crc;
  }
  
  static int io_ctl_check_crc(struct btrfs_io_ctl *io_ctl, int index)
  {
  	u32 *tmp, val;
  	u32 crc = ~(u32)0;
  	unsigned offset = 0;
  
  	if (!io_ctl->check_crcs) {
  		io_ctl_map_page(io_ctl, 0);
  		return 0;
  	}
  
  	if (index == 0)
  		offset = sizeof(u32) * io_ctl->num_pages;
  
  	tmp = page_address(io_ctl->pages[0]);
  	tmp += index;
  	val = *tmp;
  
  	io_ctl_map_page(io_ctl, 0);
  	crc = btrfs_csum_data(io_ctl->orig + offset, crc,
  			      PAGE_SIZE - offset);
  	btrfs_csum_final(crc, (u8 *)&crc);
  	if (val != crc) {
  		btrfs_err_rl(io_ctl->fs_info,
  			"csum mismatch on free space cache");
  		io_ctl_unmap_page(io_ctl);
  		return -EIO;
  	}
  
  	return 0;
  }
  
  static int io_ctl_add_entry(struct btrfs_io_ctl *io_ctl, u64 offset, u64 bytes,
  			    void *bitmap)
  {
  	struct btrfs_free_space_entry *entry;
  
  	if (!io_ctl->cur)
  		return -ENOSPC;
  
  	entry = io_ctl->cur;
  	entry->offset = cpu_to_le64(offset);
  	entry->bytes = cpu_to_le64(bytes);
  	entry->type = (bitmap) ? BTRFS_FREE_SPACE_BITMAP :
  		BTRFS_FREE_SPACE_EXTENT;
  	io_ctl->cur += sizeof(struct btrfs_free_space_entry);
  	io_ctl->size -= sizeof(struct btrfs_free_space_entry);
  
  	if (io_ctl->size >= sizeof(struct btrfs_free_space_entry))
  		return 0;
  
  	io_ctl_set_crc(io_ctl, io_ctl->index - 1);
  
  	/* No more pages to map */
  	if (io_ctl->index >= io_ctl->num_pages)
  		return 0;
  
  	/* map the next page */
  	io_ctl_map_page(io_ctl, 1);
  	return 0;
  }
  
  static int io_ctl_add_bitmap(struct btrfs_io_ctl *io_ctl, void *bitmap)
  {
  	if (!io_ctl->cur)
  		return -ENOSPC;
  
  	/*
  	 * If we aren't at the start of the current page, unmap this one and
  	 * map the next one if there is any left.
  	 */
  	if (io_ctl->cur != io_ctl->orig) {
  		io_ctl_set_crc(io_ctl, io_ctl->index - 1);
  		if (io_ctl->index >= io_ctl->num_pages)
  			return -ENOSPC;
  		io_ctl_map_page(io_ctl, 0);
  	}
  
  	memcpy(io_ctl->cur, bitmap, PAGE_SIZE);
  	io_ctl_set_crc(io_ctl, io_ctl->index - 1);
  	if (io_ctl->index < io_ctl->num_pages)
  		io_ctl_map_page(io_ctl, 0);
  	return 0;
  }
  
  static void io_ctl_zero_remaining_pages(struct btrfs_io_ctl *io_ctl)
  {
  	/*
  	 * If we're not on the boundary we know we've modified the page and we
  	 * need to crc the page.
  	 */
  	if (io_ctl->cur != io_ctl->orig)
  		io_ctl_set_crc(io_ctl, io_ctl->index - 1);
  	else
  		io_ctl_unmap_page(io_ctl);
  
  	while (io_ctl->index < io_ctl->num_pages) {
  		io_ctl_map_page(io_ctl, 1);
  		io_ctl_set_crc(io_ctl, io_ctl->index - 1);
  	}
  }
  
  static int io_ctl_read_entry(struct btrfs_io_ctl *io_ctl,
  			    struct btrfs_free_space *entry, u8 *type)
  {
  	struct btrfs_free_space_entry *e;
  	int ret;
  
  	if (!io_ctl->cur) {
  		ret = io_ctl_check_crc(io_ctl, io_ctl->index);
  		if (ret)
  			return ret;
  	}
  
  	e = io_ctl->cur;
  	entry->offset = le64_to_cpu(e->offset);
  	entry->bytes = le64_to_cpu(e->bytes);
  	*type = e->type;
  	io_ctl->cur += sizeof(struct btrfs_free_space_entry);
  	io_ctl->size -= sizeof(struct btrfs_free_space_entry);
  
  	if (io_ctl->size >= sizeof(struct btrfs_free_space_entry))
  		return 0;
  
  	io_ctl_unmap_page(io_ctl);
  
  	return 0;
  }
  
  static int io_ctl_read_bitmap(struct btrfs_io_ctl *io_ctl,
  			      struct btrfs_free_space *entry)
  {
  	int ret;
  
  	ret = io_ctl_check_crc(io_ctl, io_ctl->index);
  	if (ret)
  		return ret;
  
  	memcpy(entry->bitmap, io_ctl->cur, PAGE_SIZE);
  	io_ctl_unmap_page(io_ctl);
  
  	return 0;
  }
  
  /*
   * Since we attach pinned extents after the fact we can have contiguous sections
   * of free space that are split up in entries.  This poses a problem with the
   * tree logging stuff since it could have allocated across what appears to be 2
   * entries since we would have merged the entries when adding the pinned extents
   * back to the free space cache.  So run through the space cache that we just
   * loaded and merge contiguous entries.  This will make the log replay stuff not
   * blow up and it will make for nicer allocator behavior.
   */
  static void merge_space_tree(struct btrfs_free_space_ctl *ctl)
  {
  	struct btrfs_free_space *e, *prev = NULL;
  	struct rb_node *n;
  
  again:
  	spin_lock(&ctl->tree_lock);
  	for (n = rb_first(&ctl->free_space_offset); n; n = rb_next(n)) {
  		e = rb_entry(n, struct btrfs_free_space, offset_index);
  		if (!prev)
  			goto next;
  		if (e->bitmap || prev->bitmap)
  			goto next;
  		if (prev->offset + prev->bytes == e->offset) {
  			unlink_free_space(ctl, prev);
  			unlink_free_space(ctl, e);
  			prev->bytes += e->bytes;
  			kmem_cache_free(btrfs_free_space_cachep, e);
  			link_free_space(ctl, prev);
  			prev = NULL;
  			spin_unlock(&ctl->tree_lock);
  			goto again;
  		}
  next:
  		prev = e;
  	}
  	spin_unlock(&ctl->tree_lock);
  }
  
  static 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_fs_info *fs_info = btrfs_sb(inode->i_sb);
  	struct btrfs_free_space_header *header;
  	struct extent_buffer *leaf;
  	struct btrfs_io_ctl io_ctl;
  	struct btrfs_key key;
  	struct btrfs_free_space *e, *n;
  	LIST_HEAD(bitmaps);
  	u64 num_entries;
  	u64 num_bitmaps;
  	u64 generation;
  	u8 type;
  	int ret = 0;
  
  	/* Nothing in the space cache, goodbye */
  	if (!i_size_read(inode))
  		return 0;
  
  	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 0;
  	else if (ret > 0) {
  		btrfs_release_path(path);
  		return 0;
  	}
  
  	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) {
  		btrfs_info(fs_info,
  			   "the free space cache file (%llu) is invalid, skip it",
  			   offset);
  		return 0;
  	}
  
  	if (BTRFS_I(inode)->generation != generation) {
  		btrfs_err(fs_info,
  			  "free space inode generation (%llu) did not match free space cache generation (%llu)",
  			  BTRFS_I(inode)->generation, generation);
  		return 0;
  	}
  
  	if (!num_entries)
  		return 0;
  
  	ret = io_ctl_init(&io_ctl, inode, 0);
  	if (ret)
  		return ret;
  
  	readahead_cache(inode);
  
  	ret = io_ctl_prepare_pages(&io_ctl, inode, 1);
  	if (ret)
  		goto out;
  
  	ret = io_ctl_check_crc(&io_ctl, 0);
  	if (ret)
  		goto free_cache;
  
  	ret = io_ctl_check_generation(&io_ctl, generation);
  	if (ret)
  		goto free_cache;
  
  	while (num_entries) {
  		e = kmem_cache_zalloc(btrfs_free_space_cachep,
  				      GFP_NOFS);
  		if (!e)
  			goto free_cache;
  
  		ret = io_ctl_read_entry(&io_ctl, e, &type);
  		if (ret) {
  			kmem_cache_free(btrfs_free_space_cachep, e);
  			goto free_cache;
  		}
  
  		if (!e->bytes) {
  			kmem_cache_free(btrfs_free_space_cachep, e);
  			goto free_cache;
  		}
  
  		if (type == BTRFS_FREE_SPACE_EXTENT) {
  			spin_lock(&ctl->tree_lock);
  			ret = link_free_space(ctl, e);
  			spin_unlock(&ctl->tree_lock);
  			if (ret) {
  				btrfs_err(fs_info,
  					"Duplicate entries in free space cache, dumping");
  				kmem_cache_free(btrfs_free_space_cachep, e);
  				goto free_cache;
  			}
  		} else {
  			ASSERT(num_bitmaps);
  			num_bitmaps--;
  			e->bitmap = kzalloc(PAGE_SIZE, GFP_NOFS);
  			if (!e->bitmap) {
  				kmem_cache_free(
  					btrfs_free_space_cachep, e);
  				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) {
  				btrfs_err(fs_info,
  					"Duplicate entries in free space cache, dumping");
  				kmem_cache_free(btrfs_free_space_cachep, e);
  				goto free_cache;
  			}
  			list_add_tail(&e->list, &bitmaps);
  		}
  
  		num_entries--;
  	}
  
  	io_ctl_unmap_page(&io_ctl);
  
  	/*
  	 * We add the bitmaps at the end of the entries in order that
  	 * the bitmap entries are added to the cache.
  	 */
  	list_for_each_entry_safe(e, n, &bitmaps, list) {
  		list_del_init(&e->list);
  		ret = io_ctl_read_bitmap(&io_ctl, e);
  		if (ret)
  			goto free_cache;
  	}
  
  	io_ctl_drop_pages(&io_ctl);
  	merge_space_tree(ctl);
  	ret = 1;
  out:
  	io_ctl_free(&io_ctl);
  	return ret;
  free_cache:
  	io_ctl_drop_pages(&io_ctl);
  	__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 inode *inode;
  	struct btrfs_path *path;
  	int ret = 0;
  	bool matched;
  	u64 used = btrfs_block_group_used(&block_group->item);
  
  	/*
  	 * 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;
  	path->search_commit_root = 1;
  	path->skip_locking = 1;
  
  	inode = lookup_free_space_inode(fs_info, block_group, path);
  	if (IS_ERR(inode)) {
  		btrfs_free_path(path);
  		return 0;
  	}
  
  	/* We may have converted the inode and made the cache invalid. */
  	spin_lock(&block_group->lock);
  	if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
  		spin_unlock(&block_group->lock);
  		btrfs_free_path(path);
  		goto out;
  	}
  	spin_unlock(&block_group->lock);
  
  	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);
  		btrfs_warn(fs_info,
  			   "block group %llu has wrong amount of free space",
  			   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;
  
  		btrfs_warn(fs_info,
  			   "failed to load free space cache for block group %llu, rebuilding it now",
  			   block_group->key.objectid);
  	}
  
  	iput(inode);
  	return ret;
  }
  
  static noinline_for_stack
  int write_cache_extent_entries(struct btrfs_io_ctl *io_ctl,
  			      struct btrfs_free_space_ctl *ctl,
  			      struct btrfs_block_group_cache *block_group,
  			      int *entries, int *bitmaps,
  			      struct list_head *bitmap_list)
  {
  	int ret;
  	struct btrfs_free_cluster *cluster = NULL;
  	struct btrfs_free_cluster *cluster_locked = NULL;
  	struct rb_node *node = rb_first(&ctl->free_space_offset);
  	struct btrfs_trim_range *trim_entry;
  
  	/* 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);
  	}
  
  	if (!node && cluster) {
  		cluster_locked = cluster;
  		spin_lock(&cluster_locked->lock);
  		node = rb_first(&cluster->root);
  		cluster = NULL;
  	}
  
  	/* Write out the extent entries */
  	while (node) {
  		struct btrfs_free_space *e;
  
  		e = rb_entry(node, struct btrfs_free_space, offset_index);
  		*entries += 1;
  
  		ret = io_ctl_add_entry(io_ctl, e->offset, e->bytes,
  				       e->bitmap);
  		if (ret)
  			goto fail;
  
  		if (e->bitmap) {
  			list_add_tail(&e->list, bitmap_list);
  			*bitmaps += 1;
  		}
  		node = rb_next(node);
  		if (!node && cluster) {
  			node = rb_first(&cluster->root);
  			cluster_locked = cluster;
  			spin_lock(&cluster_locked->lock);
  			cluster = NULL;
  		}
  	}
  	if (cluster_locked) {
  		spin_unlock(&cluster_locked->lock);
  		cluster_locked = NULL;
  	}
  
  	/*
  	 * Make sure we don't miss any range that was removed from our rbtree
  	 * because trimming is running. Otherwise after a umount+mount (or crash
  	 * after committing the transaction) we would leak free space and get
  	 * an inconsistent free space cache report from fsck.
  	 */
  	list_for_each_entry(trim_entry, &ctl->trimming_ranges, list) {
  		ret = io_ctl_add_entry(io_ctl, trim_entry->start,
  				       trim_entry->bytes, NULL);
  		if (ret)
  			goto fail;
  		*entries += 1;
  	}
  
  	return 0;
  fail:
  	if (cluster_locked)
  		spin_unlock(&cluster_locked->lock);
  	return -ENOSPC;
  }
  
  static noinline_for_stack int
  update_cache_item(struct btrfs_trans_handle *trans,
  		  struct btrfs_root *root,
  		  struct inode *inode,
  		  struct btrfs_path *path, u64 offset,
  		  int entries, int bitmaps)
  {
  	struct btrfs_key key;
  	struct btrfs_free_space_header *header;
  	struct extent_buffer *leaf;
  	int ret;
  
  	key.objectid = BTRFS_FREE_SPACE_OBJECTID;
  	key.offset = offset;
  	key.type = 0;
  
  	ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
  	if (ret < 0) {
  		clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, inode->i_size - 1,
  				 EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, NULL,
  				 GFP_NOFS);
  		goto fail;
  	}
  	leaf = path->nodes[0];
  	if (ret > 0) {
  		struct btrfs_key found_key;
  		ASSERT(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) {
  			clear_extent_bit(&BTRFS_I(inode)->io_tree, 0,
  					 inode->i_size - 1,
  					 EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0,
  					 NULL, GFP_NOFS);
  			btrfs_release_path(path);
  			goto fail;
  		}
  	}
  
  	BTRFS_I(inode)->generation = trans->transid;
  	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);
  
  	return 0;
  
  fail:
  	return -1;
  }
  
  static noinline_for_stack int
  write_pinned_extent_entries(struct btrfs_fs_info *fs_info,
  			    struct btrfs_block_group_cache *block_group,
  			    struct btrfs_io_ctl *io_ctl,
  			    int *entries)
  {
  	u64 start, extent_start, extent_end, len;
  	struct extent_io_tree *unpin = NULL;
  	int ret;
  
  	if (!block_group)
  		return 0;
  
  	/*
  	 * We want to add any pinned extents to our free space cache
  	 * so we don't leak the space
  	 *
  	 * We shouldn't have switched the pinned extents yet so this is the
  	 * right one
  	 */
  	unpin = fs_info->pinned_extents;
  
  	start = block_group->key.objectid;
  
  	while (start < block_group->key.objectid + block_group->key.offset) {
  		ret = find_first_extent_bit(unpin, start,
  					    &extent_start, &extent_end,
  					    EXTENT_DIRTY, NULL);
  		if (ret)
  			return 0;
  
  		/* This pinned extent is out of our range */
  		if (extent_start >= block_group->key.objectid +
  		    block_group->key.offset)
  			return 0;
  
  		extent_start = max(extent_start, start);
  		extent_end = min(block_group->key.objectid +
  				 block_group->key.offset, extent_end + 1);
  		len = extent_end - extent_start;
  
  		*entries += 1;
  		ret = io_ctl_add_entry(io_ctl, extent_start, len, NULL);
  		if (ret)
  			return -ENOSPC;
  
  		start = extent_end;
  	}
  
  	return 0;
  }
  
  static noinline_for_stack int
  write_bitmap_entries(struct btrfs_io_ctl *io_ctl, struct list_head *bitmap_list)
  {
  	struct btrfs_free_space *entry, *next;
  	int ret;
  
  	/* Write out the bitmaps */
  	list_for_each_entry_safe(entry, next, bitmap_list, list) {
  		ret = io_ctl_add_bitmap(io_ctl, entry->bitmap);
  		if (ret)
  			return -ENOSPC;
  		list_del_init(&entry->list);
  	}
  
  	return 0;
  }
  
  static int flush_dirty_cache(struct inode *inode)
  {
  	int ret;
  
  	ret = btrfs_wait_ordered_range(inode, 0, (u64)-1);
  	if (ret)
  		clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, inode->i_size - 1,
  				 EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, NULL,
  				 GFP_NOFS);
  
  	return ret;
  }
  
  static void noinline_for_stack
  cleanup_bitmap_list(struct list_head *bitmap_list)
  {
  	struct btrfs_free_space *entry, *next;
  
  	list_for_each_entry_safe(entry, next, bitmap_list, list)
  		list_del_init(&entry->list);
  }
  
  static void noinline_for_stack
  cleanup_write_cache_enospc(struct inode *inode,
  			   struct btrfs_io_ctl *io_ctl,
  			   struct extent_state **cached_state)
  {
  	io_ctl_drop_pages(io_ctl);
  	unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
  			     i_size_read(inode) - 1, cached_state,
  			     GFP_NOFS);
  }
  
  static int __btrfs_wait_cache_io(struct btrfs_root *root,
  				 struct btrfs_trans_handle *trans,
  				 struct btrfs_block_group_cache *block_group,
  				 struct btrfs_io_ctl *io_ctl,
  				 struct btrfs_path *path, u64 offset)
  {
  	int ret;
  	struct inode *inode = io_ctl->inode;
  	struct btrfs_fs_info *fs_info;
  
  	if (!inode)
  		return 0;
  
  	fs_info = btrfs_sb(inode->i_sb);
  
  	/* Flush the dirty pages in the cache file. */
  	ret = flush_dirty_cache(inode);
  	if (ret)
  		goto out;
  
  	/* Update the cache item to tell everyone this cache file is valid. */
  	ret = update_cache_item(trans, root, inode, path, offset,
  				io_ctl->entries, io_ctl->bitmaps);
  out:
  	io_ctl_free(io_ctl);
  	if (ret) {
  		invalidate_inode_pages2(inode->i_mapping);
  		BTRFS_I(inode)->generation = 0;
  		if (block_group) {
  #ifdef DEBUG
  			btrfs_err(fs_info,
  				  "failed to write free space cache for block group %llu",
  				  block_group->key.objectid);
  #endif
  		}
  	}
  	btrfs_update_inode(trans, root, inode);
  
  	if (block_group) {
  		/* the dirty list is protected by the dirty_bgs_lock */
  		spin_lock(&trans->transaction->dirty_bgs_lock);
  
  		/* the disk_cache_state is protected by the block group lock */
  		spin_lock(&block_group->lock);
  
  		/*
  		 * only mark this as written if we didn't get put back on
  		 * the dirty list while waiting for IO.   Otherwise our
  		 * cache state won't be right, and we won't get written again
  		 */
  		if (!ret && list_empty(&block_group->dirty_list))
  			block_group->disk_cache_state = BTRFS_DC_WRITTEN;
  		else if (ret)
  			block_group->disk_cache_state = BTRFS_DC_ERROR;
  
  		spin_unlock(&block_group->lock);
  		spin_unlock(&trans->transaction->dirty_bgs_lock);
  		io_ctl->inode = NULL;
  		iput(inode);
  	}
  
  	return ret;
  
  }
  
  static int btrfs_wait_cache_io_root(struct btrfs_root *root,
  				    struct btrfs_trans_handle *trans,
  				    struct btrfs_io_ctl *io_ctl,
  				    struct btrfs_path *path)
  {
  	return __btrfs_wait_cache_io(root, trans, NULL, io_ctl, path, 0);
  }
  
  int btrfs_wait_cache_io(struct btrfs_trans_handle *trans,
  			struct btrfs_block_group_cache *block_group,
  			struct btrfs_path *path)
  {
  	return __btrfs_wait_cache_io(block_group->fs_info->tree_root, trans,
  				     block_group, &block_group->io_ctl,
  				     path, block_group->key.objectid);
  }
  
  /**
   * __btrfs_write_out_cache - write out cached info to an inode
   * @root - the root the inode belongs to
   * @ctl - the free space cache we are going to write out
   * @block_group - the block_group for this cache if it belongs to a block_group
   * @trans - the trans handle
   *
   * This function writes out a free space cache struct to disk for quick recovery
   * on mount.  This will return 0 if it was successful in writing the cache out,
   * or an errno if it was not.
   */
  static 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_io_ctl *io_ctl,
  				   struct btrfs_trans_handle *trans)
  {
  	struct btrfs_fs_info *fs_info = root->fs_info;
  	struct extent_state *cached_state = NULL;
  	LIST_HEAD(bitmap_list);
  	int entries = 0;
  	int bitmaps = 0;
  	int ret;
  	int must_iput = 0;
  
  	if (!i_size_read(inode))
  		return -EIO;
  
  	WARN_ON(io_ctl->pages);
  	ret = io_ctl_init(io_ctl, inode, 1);
  	if (ret)
  		return ret;
  
  	if (block_group && (block_group->flags & BTRFS_BLOCK_GROUP_DATA)) {
  		down_write(&block_group->data_rwsem);
  		spin_lock(&block_group->lock);
  		if (block_group->delalloc_bytes) {
  			block_group->disk_cache_state = BTRFS_DC_WRITTEN;
  			spin_unlock(&block_group->lock);
  			up_write(&block_group->data_rwsem);
  			BTRFS_I(inode)->generation = 0;
  			ret = 0;
  			must_iput = 1;
  			goto out;
  		}
  		spin_unlock(&block_group->lock);
  	}
  
  	/* Lock all pages first so we can lock the extent safely. */
  	ret = io_ctl_prepare_pages(io_ctl, inode, 0);
  	if (ret)
  		goto out;
  
  	lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
  			 &cached_state);
  
  	io_ctl_set_generation(io_ctl, trans->transid);
  
  	mutex_lock(&ctl->cache_writeout_mutex);
  	/* Write out the extent entries in the free space cache */
  	spin_lock(&ctl->tree_lock);
  	ret = write_cache_extent_entries(io_ctl, ctl,
  					 block_group, &entries, &bitmaps,
  					 &bitmap_list);
  	if (ret)
  		goto out_nospc_locked;
  
  	/*
  	 * Some spaces that are freed in the current transaction are pinned,
  	 * they will be added into free space cache after the transaction is
  	 * committed, we shouldn't lose them.
  	 *
  	 * If this changes while we are working we'll get added back to
  	 * the dirty list and redo it.  No locking needed
  	 */
  	ret = write_pinned_extent_entries(fs_info, block_group,
  					  io_ctl, &entries);
  	if (ret)
  		goto out_nospc_locked;
  
  	/*
  	 * At last, we write out all the bitmaps and keep cache_writeout_mutex
  	 * locked while doing it because a concurrent trim can be manipulating
  	 * or freeing the bitmap.
  	 */
  	ret = write_bitmap_entries(io_ctl, &bitmap_list);
  	spin_unlock(&ctl->tree_lock);
  	mutex_unlock(&ctl->cache_writeout_mutex);
  	if (ret)
  		goto out_nospc;
  
  	/* Zero out the rest of the pages just to make sure */
  	io_ctl_zero_remaining_pages(io_ctl);
  
  	/* Everything is written out, now we dirty the pages in the file. */
  	ret = btrfs_dirty_pages(inode, io_ctl->pages, io_ctl->num_pages, 0,
  				i_size_read(inode), &cached_state);
  	if (ret)
  		goto out_nospc;
  
  	if (block_group && (block_group->flags & BTRFS_BLOCK_GROUP_DATA))
  		up_write(&block_group->data_rwsem);
  	/*
  	 * Release the pages and unlock the extent, we will flush
  	 * them out later
  	 */
  	io_ctl_drop_pages(io_ctl);
  
  	unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
  			     i_size_read(inode) - 1, &cached_state, GFP_NOFS);
  
  	/*
  	 * at this point the pages are under IO and we're happy,
  	 * The caller is responsible for waiting on them and updating the
  	 * the cache and the inode
  	 */
  	io_ctl->entries = entries;
  	io_ctl->bitmaps = bitmaps;
  
  	ret = btrfs_fdatawrite_range(inode, 0, (u64)-1);
  	if (ret)
  		goto out;
  
  	return 0;
  
  out:
  	io_ctl->inode = NULL;
  	io_ctl_free(io_ctl);
  	if (ret) {
  		invalidate_inode_pages2(inode->i_mapping);
  		BTRFS_I(inode)->generation = 0;
  	}
  	btrfs_update_inode(trans, root, inode);
  	if (must_iput)
  		iput(inode);
  	return ret;
  
  out_nospc_locked:
  	cleanup_bitmap_list(&bitmap_list);
  	spin_unlock(&ctl->tree_lock);
  	mutex_unlock(&ctl->cache_writeout_mutex);
  
  out_nospc:
  	cleanup_write_cache_enospc(inode, io_ctl, &cached_state);
  
  	if (block_group && (block_group->flags & BTRFS_BLOCK_GROUP_DATA))
  		up_write(&block_group->data_rwsem);
  
  	goto out;
  }
  
  int btrfs_write_out_cache(struct btrfs_fs_info *fs_info,
  			  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;
  
  	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(fs_info, block_group, path);
  	if (IS_ERR(inode))
  		return 0;
  
  	ret = __btrfs_write_out_cache(fs_info->tree_root, inode, ctl,
  				block_group, &block_group->io_ctl, trans);
  	if (ret) {
  #ifdef DEBUG
  		btrfs_err(fs_info,
  			  "failed to write free space cache for block group %llu",
  			  block_group->key.objectid);
  #endif
  		spin_lock(&block_group->lock);
  		block_group->disk_cache_state = BTRFS_DC_ERROR;
  		spin_unlock(&block_group->lock);
  
  		block_group->io_ctl.inode = NULL;
  		iput(inode);
  	}
  
  	/*
  	 * if ret == 0 the caller is expected to call btrfs_wait_cache_io
  	 * to wait for IO and put the inode
  	 */
  
  	return ret;
  }
  
  static inline unsigned long offset_to_bit(u64 bitmap_start, u32 unit,
  					  u64 offset)
  {
  	ASSERT(offset >= bitmap_start);
  	offset -= bitmap_start;
  	return (unsigned long)(div_u64(offset, unit));
  }
  
  static inline unsigned long bytes_to_bits(u64 bytes, u32 unit)
  {
  	return (unsigned long)(div_u64(bytes, unit));
  }
  
  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 * ctl->unit;
  	bitmap_start = offset - ctl->start;
  	bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
  	bitmap_start *= bytes_per_bitmap;
  	bitmap_start += ctl->start;
  
  	return bitmap_start;
  }
  
  static int tree_insert_offset(struct rb_root *root, u64 offset,
  			      struct rb_node *node, int bitmap)
  {
  	struct rb_node **p = &root->rb_node;
  	struct rb_node *parent = NULL;
  	struct btrfs_free_space *info;
  
  	while (*p) {
  		parent = *p;
  		info = rb_entry(parent, struct btrfs_free_space, offset_index);
  
  		if (offset < info->offset) {
  			p = &(*p)->rb_left;
  		} else if (offset > info->offset) {
  			p = &(*p)->rb_right;
  		} else {
  			/*
  			 * we could have a bitmap entry and an extent entry
  			 * share the same offset.  If this is the case, we want
  			 * the extent entry to always be found first if we do a
  			 * linear search through the tree, since we want to have
  			 * the quickest allocation time, and allocating from an
  			 * extent is faster than allocating from a bitmap.  So
  			 * if we're inserting a bitmap and we find an entry at
  			 * this offset, we want to go right, or after this entry
  			 * logically.  If we are inserting an extent and we've
  			 * found a bitmap, we want to go left, or before
  			 * logically.
  			 */
  			if (bitmap) {
  				if (info->bitmap) {
  					WARN_ON_ONCE(1);
  					return -EEXIST;
  				}
  				p = &(*p)->rb_right;
  			} else {
  				if (!info->bitmap) {
  					WARN_ON_ONCE(1);
  					return -EEXIST;
  				}
  				p = &(*p)->rb_left;
  			}
  		}
  	}
  
  	rb_link_node(node, parent, p);
  	rb_insert_color(node, root);
  
  	return 0;
  }
  
  /*
   * searches the tree for the given offset.
   *
   * fuzzy - If this is set, then we are trying to make an allocation, and we just
   * want a section that has at least bytes size and comes at or after the given
   * offset.
   */
  static struct btrfs_free_space *
  tree_search_offset(struct btrfs_free_space_ctl *ctl,
  		   u64 offset, int bitmap_only, int fuzzy)
  {
  	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' */
  	while (1) {
  		if (!n) {
  			entry = NULL;
  			break;
  		}
  
  		entry = rb_entry(n, struct btrfs_free_space, offset_index);
  		prev = entry;
  
  		if (offset < entry->offset)
  			n = n->rb_left;
  		else if (offset > entry->offset)
  			n = n->rb_right;
  		else
  			break;
  	}
  
  	if (bitmap_only) {
  		if (!entry)
  			return NULL;
  		if (entry->bitmap)
  			return entry;
  
  		/*
  		 * bitmap entry and extent entry may share same offset,
  		 * in that case, bitmap entry comes after extent entry.
  		 */
  		n = rb_next(n);
  		if (!n)
  			return NULL;
  		entry = rb_entry(n, struct btrfs_free_space, offset_index);
  		if (entry->offset != offset)
  			return NULL;
  
  		WARN_ON(!entry->bitmap);
  		return entry;
  	} else if (entry) {
  		if (entry->bitmap) {
  			/*
  			 * if previous extent entry covers the offset,
  			 * we should return it instead of the bitmap entry
  			 */
  			n = rb_prev(&entry->offset_index);
  			if (n) {
  				prev = rb_entry(n, struct btrfs_free_space,
  						offset_index);
  				if (!prev->bitmap &&
  				    prev->offset + prev->bytes > offset)
  					entry = prev;
  			}
  		}
  		return entry;
  	}
  
  	if (!prev)
  		return NULL;
  
  	/* find last entry before the 'offset' */
  	entry = prev;
  	if (entry->offset > offset) {
  		n = rb_prev(&entry->offset_index);
  		if (n) {
  			entry = rb_entry(n, struct btrfs_free_space,
  					offset_index);
  			ASSERT(entry->offset <= offset);
  		} else {
  			if (fuzzy)
  				return entry;
  			else
  				return NULL;
  		}
  	}
  
  	if (entry->bitmap) {
  		n = rb_prev(&entry->offset_index);
  		if (n) {
  			prev = rb_entry(n, struct btrfs_free_space,
  					offset_index);
  			if (!prev->bitmap &&
  			    prev->offset + prev->bytes > offset)
  				return prev;
  		}
  		if (entry->offset + BITS_PER_BITMAP * ctl->unit > offset)
  			return entry;
  	} else if (entry->offset + entry->bytes > offset)
  		return entry;
  
  	if (!fuzzy)
  		return NULL;
  
  	while (1) {
  		if (entry->bitmap) {
  			if (entry->offset + BITS_PER_BITMAP *
  			    ctl->unit > offset)
  				break;
  		} else {
  			if (entry->offset + entry->bytes > offset)
  				break;
  		}
  
  		n = rb_next(&entry->offset_index);
  		if (!n)
  			return NULL;
  		entry = rb_entry(n, struct btrfs_free_space, offset_index);
  	}
  	return entry;
  }
  
  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)
  {
  	__unlink_free_space(ctl, info);
  	ctl->free_space -= info->bytes;
  }
  
  static int link_free_space(struct btrfs_free_space_ctl *ctl,
  			   struct btrfs_free_space *info)
  {
  	int ret = 0;
  
  	ASSERT(info->bytes || info->bitmap);
  	ret = tree_insert_offset(&ctl->free_space_offset, info->offset,
  				 &info->offset_index, (info->bitmap != NULL));
  	if (ret)
  		return ret;
  
  	ctl->free_space += info->bytes;
  	ctl->free_extents++;
  	return ret;
  }
  
  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 * ctl->unit;
  	u64 max_bitmaps = div64_u64(size + bytes_per_bg - 1, bytes_per_bg);
  
  	max_bitmaps = max_t(u64, max_bitmaps, 1);
  
  	ASSERT(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
  	 */
  	if (size < SZ_1G)
  		max_bytes = MAX_CACHE_BYTES_PER_GIG;
  	else
  		max_bytes = MAX_CACHE_BYTES_PER_GIG * div_u64(size, SZ_1G);
  
  	/*
  	 * 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 = (ctl->total_bitmaps + 1) * ctl->unit;
  
  	if (bitmap_bytes >= max_bytes) {
  		ctl->extents_thresh = 0;
  		return;
  	}
  
  	/*
  	 * we want the extent entry threshold to always be at most 1/2 the max
  	 * bytes we can have, or whatever is less than that.
  	 */
  	extent_bytes = max_bytes - bitmap_bytes;
  	extent_bytes = min_t(u64, extent_bytes, max_bytes >> 1);
  
  	ctl->extents_thresh =
  		div_u64(extent_bytes, sizeof(struct btrfs_free_space));
  }
  
  static inline void __bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
  				       struct btrfs_free_space *info,
  				       u64 offset, u64 bytes)
  {
  	unsigned long start, count;
  
  	start = offset_to_bit(info->offset, ctl->unit, offset);
  	count = bytes_to_bits(bytes, ctl->unit);
  	ASSERT(start + count <= BITS_PER_BITMAP);
  
  	bitmap_clear(info->bitmap, start, count);
  
  	info->bytes -= bytes;
  }
  
  static void bitmap_clear_bits(struct btrfs_free_space_ctl *ctl,
  			      struct btrfs_free_space *info, u64 offset,
  			      u64 bytes)
  {
  	__bitmap_clear_bits(ctl, info, offset, bytes);
  	ctl->free_space -= bytes;
  }
  
  static void bitmap_set_bits(struct btrfs_free_space_ctl *ctl,
  			    struct btrfs_free_space *info, u64 offset,
  			    u64 bytes)
  {
  	unsigned long start, count;
  
  	start = offset_to_bit(info->offset, ctl->unit, offset);
  	count = bytes_to_bits(bytes, ctl->unit);
  	ASSERT(start + count <= BITS_PER_BITMAP);
  
  	bitmap_set(info->bitmap, start, count);
  
  	info->bytes += bytes;
  	ctl->free_space += bytes;
  }
  
  /*
   * If we can not find suitable extent, we will use bytes to record
   * the size of the max extent.
   */
  static int search_bitmap(struct btrfs_free_space_ctl *ctl,
  			 struct btrfs_free_space *bitmap_info, u64 *offset,
  			 u64 *bytes, bool for_alloc)
  {
  	unsigned long found_bits = 0;
  	unsigned long max_bits = 0;
  	unsigned long bits, i;
  	unsigned long next_zero;
  	unsigned long extent_bits;
  
  	/*
  	 * Skip searching the bitmap if we don't have a contiguous section that
  	 * is large enough for this allocation.
  	 */
  	if (for_alloc &&
  	    bitmap_info->max_extent_size &&
  	    bitmap_info->max_extent_size < *bytes) {
  		*bytes = bitmap_info->max_extent_size;
  		return -1;
  	}
  
  	i = offset_to_bit(bitmap_info->offset, ctl->unit,
  			  max_t(u64, *offset, bitmap_info->offset));
  	bits = bytes_to_bits(*bytes, ctl->unit);
  
  	for_each_set_bit_from(i, bitmap_info->bitmap, BITS_PER_BITMAP) {
  		if (for_alloc && bits == 1) {
  			found_bits = 1;
  			break;
  		}
  		next_zero = find_next_zero_bit(bitmap_info->bitmap,
  					       BITS_PER_BITMAP, i);
  		extent_bits = next_zero - i;
  		if (extent_bits >= bits) {
  			found_bits = extent_bits;
  			break;
  		} else if (extent_bits > max_bits) {
  			max_bits = extent_bits;
  		}
  		i = next_zero;
  	}
  
  	if (found_bits) {
  		*offset = (u64)(i * ctl->unit) + bitmap_info->offset;
  		*bytes = (u64)(found_bits) * ctl->unit;
  		return 0;
  	}
  
  	*bytes = (u64)(max_bits) * ctl->unit;
  	bitmap_info->max_extent_size = *bytes;
  	return -1;
  }
  
  /* Cache the size of the max extent in bytes */
  static struct btrfs_free_space *
  find_free_space(struct btrfs_free_space_ctl *ctl, u64 *offset, u64 *bytes,
  		unsigned long align, u64 *max_extent_size)
  {
  	struct btrfs_free_space *entry;
  	struct rb_node *node;
  	u64 tmp;
  	u64 align_off;
  	int ret;
  
  	if (!ctl->free_space_offset.rb_node)
  		goto out;
  
  	entry = tree_search_offset(ctl, offset_to_bitmap(ctl, *offset), 0, 1);
  	if (!entry)
  		goto out;
  
  	for (node = &entry->offset_index; node; node = rb_next(node)) {
  		entry = rb_entry(node, struct btrfs_free_space, offset_index);
  		if (entry->bytes < *bytes) {
  			if (entry->bytes > *max_extent_size)
  				*max_extent_size = entry->bytes;
  			continue;
  		}
  
  		/* make sure the space returned is big enough
  		 * to match our requested alignment
  		 */
  		if (*bytes >= align) {
  			tmp = entry->offset - ctl->start + align - 1;
  			tmp = div64_u64(tmp, align);
  			tmp = tmp * align + ctl->start;
  			align_off = tmp - entry->offset;
  		} else {
  			align_off = 0;
  			tmp = entry->offset;
  		}
  
  		if (entry->bytes < *bytes + align_off) {
  			if (entry->bytes > *max_extent_size)
  				*max_extent_size = entry->bytes;
  			continue;
  		}
  
  		if (entry->bitmap) {
  			u64 size = *bytes;
  
  			ret = search_bitmap(ctl, entry, &tmp, &size, true);
  			if (!ret) {
  				*offset = tmp;
  				*bytes = size;
  				return entry;
  			} else if (size > *max_extent_size) {
  				*max_extent_size = size;
  			}
  			continue;
  		}
  
  		*offset = tmp;
  		*bytes = entry->bytes - align_off;
  		return entry;
  	}
  out:
  	return NULL;
  }
  
  static void add_new_bitmap(struct btrfs_free_space_ctl *ctl,
  			   struct btrfs_free_space *info, u64 offset)
  {
  	info->offset = offset_to_bitmap(ctl, offset);
  	info->bytes = 0;
  	INIT_LIST_HEAD(&info->list);
  	link_free_space(ctl, info);
  	ctl->total_bitmaps++;
  
  	ctl->op->recalc_thresholds(ctl);
  }
  
  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)
  {
  	u64 end;
  	u64 search_start, search_bytes;
  	int ret;
  
  again:
  	end = bitmap_info->offset + (u64)(BITS_PER_BITMAP * ctl->unit) - 1;
  
  	/*
  	 * We need to search for bits in this bitmap.  We could only cover some
  	 * of the extent in this bitmap thanks to how we add space, so we need
  	 * to search for as much as it as we can and clear that amount, and then
  	 * go searching for the next bit.
  	 */
  	search_start = *offset;
  	search_bytes = ctl->unit;
  	search_bytes = min(search_bytes, end - search_start + 1);
  	ret = search_bitmap(ctl, bitmap_info, &search_start, &search_bytes,
  			    false);
  	if (ret < 0 || search_start != *offset)
  		return -EINVAL;
  
  	/* We may have found more bits than what we need */
  	search_bytes = min(search_bytes, *bytes);
  
  	/* Cannot clear past the end of the bitmap */
  	search_bytes = min(search_bytes, end - search_start + 1);
  
  	bitmap_clear_bits(ctl, bitmap_info, search_start, search_bytes);
  	*offset += search_bytes;
  	*bytes -= search_bytes;
  
  	if (*bytes) {
  		struct rb_node *next = rb_next(&bitmap_info->offset_index);
  		if (!bitmap_info->bytes)
  			free_bitmap(ctl, bitmap_info);
  
  		/*
  		 * no entry after this bitmap, but we still have bytes to
  		 * remove, so something has gone wrong.
  		 */
  		if (!next)
  			return -EINVAL;
  
  		bitmap_info = rb_entry(next, struct btrfs_free_space,
  				       offset_index);
  
  		/*
  		 * if the next entry isn't a bitmap we need to return to let the
  		 * extent stuff do its work.
  		 */
  		if (!bitmap_info->bitmap)
  			return -EAGAIN;
  
  		/*
  		 * Ok the next item is a bitmap, but it may not actually hold
  		 * the information for the rest of this free space stuff, so
  		 * look for it, and if we don't find it return so we can try
  		 * everything over again.
  		 */
  		search_start = *offset;
  		search_bytes = ctl->unit;
  		ret = search_bitmap(ctl, bitmap_info, &search_start,
  				    &search_bytes, false);
  		if (ret < 0 || search_start != *offset)
  			return -EAGAIN;
  
  		goto again;
  	} else if (!bitmap_info->bytes)
  		free_bitmap(ctl, bitmap_info);
  
  	return 0;
  }
  
  static u64 add_bytes_to_bitmap(struct btrfs_free_space_ctl *ctl,
  			       struct btrfs_free_space *info, u64 offset,
  			       u64 bytes)
  {
  	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);
  
  	/*
  	 * We set some bytes, we have no idea what the max extent size is
  	 * anymore.
  	 */
  	info->max_extent_size = 0;
  
  	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;
  	struct btrfs_fs_info *fs_info = block_group->fs_info;
  	bool forced = false;
  
  #ifdef CONFIG_BTRFS_DEBUG
  	if (btrfs_should_fragment_free_space(block_group))
  		forced = true;
  #endif
  
  	/*
  	 * 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 (!forced && 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 plenty
  		 * 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 <= fs_info->sectorsize * 4) {
  			if (ctl->free_extents * 2 <= ctl->extents_thresh)
  				return false;
  		} else {
  			return false;
  		}
  	}
  
  	/*
  	 * The original block groups from mkfs can be really small, like 8
  	 * megabytes, so don't bother with a bitmap for those entries.  However
  	 * some block groups can be smaller than what a bitmap would cover but
  	 * are still large enough that they could overflow the 32k memory limit,
  	 * so allow those block groups to still be allowed to have a bitmap
  	 * entry.
  	 */
  	if (((BITS_PER_BITMAP * ctl->unit) >> 1) > block_group->key.offset)
  		return false;
  
  	return true;
  }
  
  static const 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:
  	/*
  	 * 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) {
  		ASSERT(added == 0);
  		goto new_bitmap;
  	}
  
  	bytes_added = add_bytes_to_bitmap(ctl, bitmap_info, offset, bytes);
  	bytes -= bytes_added;
  	offset += bytes_added;
  	added = 0;
  
  	if (!bytes) {
  		ret = 1;
  		goto out;
  	} else
  		goto again;
  
  new_bitmap:
  	if (info && info->bitmap) {
  		add_new_bitmap(ctl, info, offset);
  		added = 1;
  		info = NULL;
  		goto again;
  	} else {
  		spin_unlock(&ctl->tree_lock);
  
  		/* no pre-allocated info, allocate a new one */
  		if (!info) {
  			info = kmem_cache_zalloc(btrfs_free_space_cachep,
  						 GFP_NOFS);
  			if (!info) {
  				spin_lock(&ctl->tree_lock);
  				ret = -ENOMEM;
  				goto out;
  			}
  		}
  
  		/* allocate the bitmap */
  		info->bitmap = kzalloc(PAGE_SIZE, GFP_NOFS);
  		spin_lock(&ctl->tree_lock);
  		if (!info->bitmap) {
  			ret = -ENOMEM;
  			goto out;
  		}
  		goto again;
  	}
  
  out:
  	if (info) {
  		if (info->bitmap)
  			kfree(info->bitmap);
  		kmem_cache_free(btrfs_free_space_cachep, info);
  	}
  
  	return ret;
  }
  
  static bool try_merge_free_space(struct btrfs_free_space_ctl *ctl,
  			  struct btrfs_free_space *info, bool update_stat)
  {
  	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(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(ctl, offset - 1, 0, 0);
  
  	if (right_info && !right_info->bitmap) {
  		if (update_stat)
  			unlink_free_space(ctl, right_info);
  		else
  			__unlink_free_space(ctl, right_info);
  		info->bytes += right_info->bytes;
  		kmem_cache_free(btrfs_free_space_cachep, right_info);
  		merged = true;
  	}
  
  	if (left_info && !left_info->bitmap &&
  	    left_info->offset + left_info->bytes == offset) {
  		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;
  		kmem_cache_free(btrfs_free_space_cachep, left_info);
  		merged = true;
  	}
  
  	return merged;
  }
  
  static bool steal_from_bitmap_to_end(struct btrfs_free_space_ctl *ctl,
  				     struct btrfs_free_space *info,
  				     bool update_stat)
  {
  	struct btrfs_free_space *bitmap;
  	unsigned long i;
  	unsigned long j;
  	const u64 end = info->offset + info->bytes;
  	const u64 bitmap_offset = offset_to_bitmap(ctl, end);
  	u64 bytes;
  
  	bitmap = tree_search_offset(ctl, bitmap_offset, 1, 0);
  	if (!bitmap)
  		return false;
  
  	i = offset_to_bit(bitmap->offset, ctl->unit, end);
  	j = find_next_zero_bit(bitmap->bitmap, BITS_PER_BITMAP, i);
  	if (j == i)
  		return false;
  	bytes = (j - i) * ctl->unit;
  	info->bytes += bytes;
  
  	if (update_stat)
  		bitmap_clear_bits(ctl, bitmap, end, bytes);
  	else
  		__bitmap_clear_bits(ctl, bitmap, end, bytes);
  
  	if (!bitmap->bytes)
  		free_bitmap(ctl, bitmap);
  
  	return true;
  }
  
  static bool steal_from_bitmap_to_front(struct btrfs_free_space_ctl *ctl,
  				       struct btrfs_free_space *info,
  				       bool update_stat)
  {
  	struct btrfs_free_space *bitmap;
  	u64 bitmap_offset;
  	unsigned long i;
  	unsigned long j;
  	unsigned long prev_j;
  	u64 bytes;
  
  	bitmap_offset = offset_to_bitmap(ctl, info->offset);
  	/* If we're on a boundary, try the previous logical bitmap. */
  	if (bitmap_offset == info->offset) {
  		if (info->offset == 0)
  			return false;
  		bitmap_offset = offset_to_bitmap(ctl, info->offset - 1);
  	}
  
  	bitmap = tree_search_offset(ctl, bitmap_offset, 1, 0);
  	if (!bitmap)
  		return false;
  
  	i = offset_to_bit(bitmap->offset, ctl->unit, info->offset) - 1;
  	j = 0;
  	prev_j = (unsigned long)-1;
  	for_each_clear_bit_from(j, bitmap->bitmap, BITS_PER_BITMAP) {
  		if (j > i)
  			break;
  		prev_j = j;
  	}
  	if (prev_j == i)
  		return false;
  
  	if (prev_j == (unsigned long)-1)
  		bytes = (i + 1) * ctl->unit;
  	else
  		bytes = (i - prev_j) * ctl->unit;
  
  	info->offset -= bytes;
  	info->bytes += bytes;
  
  	if (update_stat)
  		bitmap_clear_bits(ctl, bitmap, info->offset, bytes);
  	else
  		__bitmap_clear_bits(ctl, bitmap, info->offset, bytes);
  
  	if (!bitmap->bytes)
  		free_bitmap(ctl, bitmap);
  
  	return true;
  }
  
  /*
   * We prefer always to allocate from extent entries, both for clustered and
   * non-clustered allocation requests. So when attempting to add a new extent
   * entry, try to see if there's adjacent free space in bitmap entries, and if
   * there is, migrate that space from the bitmaps to the extent.
   * Like this we get better chances of satisfying space allocation requests
   * because we attempt to satisfy them based on a single cache entry, and never
   * on 2 or more entries - even if the entries represent a contiguous free space
   * region (e.g. 1 extent entry + 1 bitmap entry starting where the extent entry
   * ends).
   */
  static void steal_from_bitmap(struct btrfs_free_space_ctl *ctl,
  			      struct btrfs_free_space *info,
  			      bool update_stat)
  {
  	/*
  	 * Only work with disconnected entries, as we can change their offset,
  	 * and must be extent entries.
  	 */
  	ASSERT(!info->bitmap);
  	ASSERT(RB_EMPTY_NODE(&info->offset_index));
  
  	if (ctl->total_bitmaps > 0) {
  		bool stole_end;
  		bool stole_front = false;
  
  		stole_end = steal_from_bitmap_to_end(ctl, info, update_stat);
  		if (ctl->total_bitmaps > 0)
  			stole_front = steal_from_bitmap_to_front(ctl, info,
  								 update_stat);
  
  		if (stole_end || stole_front)
  			try_merge_free_space(ctl, info, update_stat);
  	}
  }
  
  int __btrfs_add_free_space(struct btrfs_fs_info *fs_info,
  			   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;
  	RB_CLEAR_NODE(&info->offset_index);
  
  	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:
  	/*
  	 * Only steal free space from adjacent bitmaps if we're sure we're not
  	 * going to add the new free space to existing bitmap entries - because
  	 * that would mean unnecessary work that would be reverted. Therefore
  	 * attempt to steal space from bitmaps if we're adding an extent entry.
  	 */
  	steal_from_bitmap(ctl, info, true);
  
  	ret = link_free_space(ctl, info);
  	if (ret)
  		kmem_cache_free(btrfs_free_space_cachep, info);
  out:
  	spin_unlock(&ctl->tree_lock);
  
  	if (ret) {
  		btrfs_crit(fs_info, "unable to add free space :%d", ret);
  		ASSERT(ret != -EEXIST);
  	}
  
  	return ret;
  }
  
  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;
  	int ret;
  	bool re_search = false;
  
  	spin_lock(&ctl->tree_lock);
  
  again:
  	ret = 0;
  	if (!bytes)
  		goto out_lock;
  
  	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(ctl, offset_to_bitmap(ctl, offset),
  					  1, 0);
  		if (!info) {
  			/*
  			 * If we found a partial bit of our free space in a
  			 * bitmap but then couldn't find the other part this may
  			 * be a problem, so WARN about it.
  			 */
  			WARN_ON(re_search);
  			goto out_lock;
  		}
  	}
  
  	re_search = false;
  	if (!info->bitmap) {
  		unlink_free_space(ctl, info);
  		if (offset == info->offset) {
  			u64 to_free = min(bytes, info->bytes);
  
  			info->bytes -= to_free;
  			info->offset += to_free;
  			if (info->bytes) {
  				ret = link_free_space(ctl, info);
  				WARN_ON(ret);
  			} else {
  				kmem_cache_free(btrfs_free_space_cachep, info);
  			}
  
  			offset += to_free;
  			bytes -= to_free;
  			goto again;
  		} else {
  			u64 old_end = info->bytes + info->offset;
  
  			info->bytes = offset - info->offset;
  			ret = link_free_space(ctl, info);
  			WARN_ON(ret);
  			if (ret)
  				goto out_lock;
  
  			/* Not enough bytes in this entry to satisfy us */
  			if (old_end < offset + bytes) {
  				bytes -= old_end - offset;
  				offset = old_end;
  				goto again;
  			} else if (old_end == offset + bytes) {
  				/* all done */
  				goto out_lock;
  			}
  			spin_unlock(&ctl->tree_lock);
  
  			ret = btrfs_add_free_space(block_group, offset + bytes,
  						   old_end - (offset + bytes));
  			WARN_ON(ret);
  			goto out;
  		}
  	}
  
  	ret = remove_from_bitmap(ctl, info, &offset, &bytes);
  	if (ret == -EAGAIN) {
  		re_search = true;
  		goto again;
  	}
  out_lock:
  	spin_unlock(&ctl->tree_lock);
  out:
  	return ret;
  }
  
  void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
  			   u64 bytes)
  {
  	struct btrfs_fs_info *fs_info = block_group->fs_info;
  	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(&ctl->free_space_offset); n; n = rb_next(n)) {
  		info = rb_entry(n, struct btrfs_free_space, offset_index);
  		if (info->bytes >= bytes && !block_group->ro)
  			count++;
  		btrfs_crit(fs_info, "entry offset %llu, bytes %llu, bitmap %s",
  			   info->offset, info->bytes,
  		       (info->bitmap) ? "yes" : "no");
  	}
  	btrfs_info(fs_info, "block group has cluster?: %s",
  	       list_empty(&block_group->cluster_list) ? "no" : "yes");
  	btrfs_info(fs_info,
  		   "%d blocks of free space at or bigger than bytes is", count);
  }
  
  void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group)
  {
  	struct btrfs_fs_info *fs_info = block_group->fs_info;
  	struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
  
  	spin_lock_init(&ctl->tree_lock);
  	ctl->unit = fs_info->sectorsize;
  	ctl->start = block_group->key.objectid;
  	ctl->private = block_group;
  	ctl->op = &free_space_op;
  	INIT_LIST_HEAD(&ctl->trimming_ranges);
  	mutex_init(&ctl->cache_writeout_mutex);
  
  	/*
  	 * 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 = (SZ_32K / 2) / sizeof(struct btrfs_free_space);
  }
  
  /*
   * for a given cluster, put all of its extents back into the free
   * space cache.  If the block group passed doesn't match the block group
   * pointed to by the cluster, someone else raced in and freed the
   * cluster already.  In that case, we just return without changing anything
   */
  static int
  __btrfs_return_cluster_to_free_space(
  			     struct btrfs_block_group_cache *block_group,
  			     struct btrfs_free_cluster *cluster)
  {
  	struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
  	struct btrfs_free_space *entry;
  	struct rb_node *node;
  
  	spin_lock(&cluster->lock);
  	if (cluster->block_group != block_group)
  		goto out;
  
  	cluster->block_group = NULL;
  	cluster->window_start = 0;
  	list_del_init(&cluster->block_group_list);
  
  	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);
  		RB_CLEAR_NODE(&entry->offset_index);
  
  		bitmap = (entry->bitmap != NULL);
  		if (!bitmap) {
  			try_merge_free_space(ctl, entry, false);
  			steal_from_bitmap(ctl, entry, false);
  		}
  		tree_insert_offset(&ctl->free_space_offset,
  				   entry->offset, &entry->offset_index, bitmap);
  	}
  	cluster->root = RB_ROOT;
  
  out:
  	spin_unlock(&cluster->lock);
  	btrfs_put_block_group(block_group);
  	return 0;
  }
  
  static 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);
  		}
  
  		cond_resched_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(&ctl->tree_lock);
  	while ((head = block_group->cluster_list.next) !=
  	       &block_group->cluster_list) {
  		cluster = list_entry(head, struct btrfs_free_cluster,
  				     block_group_list);
  
  		WARN_ON(cluster->block_group != block_group);
  		__btrfs_return_cluster_to_free_space(block_group, cluster);
  
  		cond_resched_lock(&ctl->tree_lock);
  	}
  	__btrfs_remove_free_space_cache_locked(ctl);
  	spin_unlock(&ctl->tree_lock);
  
  }
  
  u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
  			       u64 offset, u64 bytes, u64 empty_size,
  			       u64 *max_extent_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;
  	u64 align_gap = 0;
  	u64 align_gap_len = 0;
  
  	spin_lock(&ctl->tree_lock);
  	entry = find_free_space(ctl, &offset, &bytes_search,
  				block_group->full_stripe_len, max_extent_size);
  	if (!entry)
  		goto out;
  
  	ret = offset;
  	if (entry->bitmap) {
  		bitmap_clear_bits(ctl, entry, offset, bytes);
  		if (!entry->bytes)
  			free_bitmap(ctl, entry);
  	} else {
  		unlink_free_space(ctl, entry);
  		align_gap_len = offset - entry->offset;
  		align_gap = entry->offset;
  
  		entry->offset = offset + bytes;
  		WARN_ON(entry->bytes < bytes + align_gap_len);
  
  		entry->bytes -= bytes + align_gap_len;
  		if (!entry->bytes)
  			kmem_cache_free(btrfs_free_space_cachep, entry);
  		else
  			link_free_space(ctl, entry);
  	}
  out:
  	spin_unlock(&ctl->tree_lock);
  
  	if (align_gap_len)
  		__btrfs_add_free_space(block_group->fs_info, ctl,
  				       align_gap, align_gap_len);
  	return ret;
  }
  
  /*
   * given a cluster, put all of its extents back into the free space
   * cache.  If a block group is passed, this function will only free
   * a cluster that belongs to the passed block group.
   *
   * Otherwise, it'll get a reference on the block group pointed to by the
   * cluster and remove the cluster from it.
   */
  int btrfs_return_cluster_to_free_space(
  			       struct btrfs_block_group_cache *block_group,
  			       struct btrfs_free_cluster *cluster)
  {
  	struct btrfs_free_space_ctl *ctl;
  	int ret;
  
  	/* first, get a safe pointer to the block group */
  	spin_lock(&cluster->lock);
  	if (!block_group) {
  		block_group = cluster->block_group;
  		if (!block_group) {
  			spin_unlock(&cluster->lock);
  			return 0;
  		}
  	} else if (cluster->block_group != block_group) {
  		/* someone else has already freed it don't redo their work */
  		spin_unlock(&cluster->lock);
  		return 0;
  	}
  	atomic_inc(&block_group->count);
  	spin_unlock(&cluster->lock);
  
  	ctl = block_group->free_space_ctl;
  
  	/* now return any extents the cluster had on it */
  	spin_lock(&ctl->tree_lock);
  	ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
  	spin_unlock(&ctl->tree_lock);
  
  	/* finally drop our ref */
  	btrfs_put_block_group(block_group);
  	return ret;
  }
  
  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,
  				   u64 *max_extent_size)
  {
  	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;
  
  	search_start = min_start;
  	search_bytes = bytes;
  
  	err = search_bitmap(ctl, entry, &search_start, &search_bytes, true);
  	if (err) {
  		if (search_bytes > *max_extent_size)
  			*max_extent_size = search_bytes;
  		return 0;
  	}
  
  	ret = search_start;
  	__bitmap_clear_bits(ctl, entry, ret, bytes);
  
  	return ret;
  }
  
  /*
   * given a cluster, try to allocate 'bytes' from it, returns 0
   * if it couldn't find anything suitably large, or a logical disk offset
   * if things worked out
   */
  u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
  			     struct btrfs_free_cluster *cluster, u64 bytes,
  			     u64 min_start, u64 *max_extent_size)
  {
  	struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
  	struct btrfs_free_space *entry = NULL;
  	struct rb_node *node;
  	u64 ret = 0;
  
  	spin_lock(&cluster->lock);
  	if (bytes > cluster->max_size)
  		goto out;
  
  	if (cluster->block_group != block_group)
  		goto out;
  
  	node = rb_first(&cluster->root);
  	if (!node)
  		goto out;
  
  	entry = rb_entry(node, struct btrfs_free_space, offset_index);
  	while (1) {
  		if (entry->bytes < bytes && entry->bytes > *max_extent_size)
  			*max_extent_size = entry->bytes;
  
  		if (entry->bytes < bytes ||
  		    (!entry->bitmap && entry->offset < min_start)) {
  			node = rb_next(&entry->offset_index);
  			if (!node)
  				break;
  			entry = rb_entry(node, struct btrfs_free_space,
  					 offset_index);
  			continue;
  		}
  
  		if (entry->bitmap) {
  			ret = btrfs_alloc_from_bitmap(block_group,
  						      cluster, entry, bytes,
  						      cluster->window_start,
  						      max_extent_size);
  			if (ret == 0) {
  				node = rb_next(&entry->offset_index);
  				if (!node)
  					break;
  				entry = rb_entry(node, struct btrfs_free_space,
  						 offset_index);
  				continue;
  			}
  			cluster->window_start += bytes;
  		} else {
  			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;
  }
  
  static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
  				struct btrfs_free_space *entry,
  				struct btrfs_free_cluster *cluster,
  				u64 offset, u64 bytes,
  				u64 cont1_bytes, u64 min_bytes)
  {
  	struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
  	unsigned long next_zero;
  	unsigned long i;
  	unsigned long want_bits;
  	unsigned long min_bits;
  	unsigned long found_bits;
  	unsigned long max_bits = 0;
  	unsigned long start = 0;
  	unsigned long total_found = 0;
  	int ret;
  
  	i = offset_to_bit(entry->offset, ctl->unit,
  			  max_t(u64, offset, entry->offset));
  	want_bits = bytes_to_bits(bytes, ctl->unit);
  	min_bits = bytes_to_bits(min_bytes, ctl->unit);
  
  	/*
  	 * Don't bother looking for a cluster in this bitmap if it's heavily
  	 * fragmented.
  	 */
  	if (entry->max_extent_size &&
  	    entry->max_extent_size < cont1_bytes)
  		return -ENOSPC;
  again:
  	found_bits = 0;
  	for_each_set_bit_from(i, entry->bitmap, BITS_PER_BITMAP) {
  		next_zero = find_next_zero_bit(entry->bitmap,
  					       BITS_PER_BITMAP, i);
  		if (next_zero - i >= min_bits) {
  			found_bits = next_zero - i;
  			if (found_bits > max_bits)
  				max_bits = found_bits;
  			break;
  		}
  		if (next_zero - i > max_bits)
  			max_bits = next_zero - i;
  		i = next_zero;
  	}
  
  	if (!found_bits) {
  		entry->max_extent_size = (u64)max_bits * ctl->unit;
  		return -ENOSPC;
  	}
  
  	if (!total_found) {
  		start = i;
  		cluster->max_size = 0;
  	}
  
  	total_found += found_bits;
  
  	if (cluster->max_size < found_bits * ctl->unit)
  		cluster->max_size = found_bits * ctl->unit;
  
  	if (total_found < want_bits || cluster->max_size < cont1_bytes) {
  		i = next_zero + 1;
  		goto again;
  	}
  
  	cluster->window_start = start * ctl->unit + entry->offset;
  	rb_erase(&entry->offset_index, &ctl->free_space_offset);
  	ret = tree_insert_offset(&cluster->root, entry->offset,
  				 &entry->offset_index, 1);
  	ASSERT(!ret); /* -EEXIST; Logic error */
  
  	trace_btrfs_setup_cluster(block_group, cluster,
  				  total_found * ctl->unit, 1);
  	return 0;
  }
  
  /*
   * This searches the block group for just extents to fill the cluster with.
   * Try to find a cluster with at least bytes total bytes, at least one
   * extent of cont1_bytes, and other clusters of at least min_bytes.
   */
  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 cont1_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 *last;
  	struct rb_node *node;
  	u64 window_free;
  	u64 max_extent;
  	u64 total_size = 0;
  
  	entry = tree_search_offset(ctl, offset, 0, 1);
  	if (!entry)
  		return -ENOSPC;
  
  	/*
  	 * We don't want bitmaps, so just move along until we find a normal
  	 * extent entry.
  	 */
  	while (entry->bitmap || entry->bytes < min_bytes) {
  		if (entry->bitmap && 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);
  	}
  
  	window_free = entry->bytes;
  	max_extent = entry->bytes;
  	first = entry;
  	last = entry;
  
  	for (node = rb_next(&entry->offset_index); node;
  	     node = rb_next(&entry->offset_index)) {
  		entry = rb_entry(node, struct btrfs_free_space, offset_index);
  
  		if (entry->bitmap) {
  			if (list_empty(&entry->list))
  				list_add_tail(&entry->list, bitmaps);
  			continue;
  		}
  
  		if (entry->bytes < min_bytes)
  			continue;
  
  		last = entry;
  		window_free += entry->bytes;
  		if (entry->bytes > max_extent)
  			max_extent = entry->bytes;
  	}
  
  	if (window_free < bytes || max_extent < cont1_bytes)
  		return -ENOSPC;
  
  	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
  	 */
  	do {
  		int ret;
  
  		entry = rb_entry(node, struct btrfs_free_space, offset_index);
  		node = rb_next(&entry->offset_index);
  		if (entry->bitmap || entry->bytes < min_bytes)
  			continue;
  
  		rb_erase(&entry->offset_index, &ctl->free_space_offset);
  		ret = tree_insert_offset(&cluster->root, entry->offset,
  					 &entry->offset_index, 0);
  		total_size += entry->bytes;
  		ASSERT(!ret); /* -EEXIST; Logic error */
  	} while (node && entry != last);
  
  	cluster->max_size = max_extent;
  	trace_btrfs_setup_cluster(block_group, cluster, total_size, 0);
  	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 cont1_bytes, u64 min_bytes)
  {
  	struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
  	struct btrfs_free_space *entry = NULL;
  	int ret = -ENOSPC;
  	u64 bitmap_offset = offset_to_bitmap(ctl, offset);
  
  	if (ctl->total_bitmaps == 0)
  		return -ENOSPC;
  
  	/*
  	 * The bitmap that covers offset won't be in the list unless offset
  	 * is just its start offset.
  	 */
  	if (!list_empty(bitmaps))
  		entry = list_first_entry(bitmaps, struct btrfs_free_space, list);
  
  	if (!entry || entry->offset != bitmap_offset) {
  		entry = tree_search_offset(ctl, bitmap_offset, 1, 0);
  		if (entry && list_empty(&entry->list))
  			list_add(&entry->list, bitmaps);
  	}
  
  	list_for_each_entry(entry, bitmaps, list) {
  		if (entry->bytes < bytes)
  			continue;
  		ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
  					   bytes, cont1_bytes, min_bytes);
  		if (!ret)
  			return 0;
  	}
  
  	/*
  	 * The bitmaps list has all the bitmaps that record free space
  	 * starting after offset, so no more search is required.
  	 */
  	return -ENOSPC;
  }
  
  /*
   * here we try to find a cluster of blocks in a block group.  The goal
   * is to find at least bytes+empty_size.
   * 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_fs_info *fs_info,
  			     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 btrfs_free_space *entry, *tmp;
  	LIST_HEAD(bitmaps);
  	u64 min_bytes;
  	u64 cont1_bytes;
  	int ret;
  
  	/*
  	 * Choose the minimum extent size we'll require for this
  	 * cluster.  For SSD_SPREAD, don't allow any fragmentation.
  	 * For metadata, allow allocates with smaller extents.  For
  	 * data, keep it dense.
  	 */
  	if (btrfs_test_opt(fs_info, SSD_SPREAD)) {
  		cont1_bytes = min_bytes = bytes + empty_size;
  	} else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
  		cont1_bytes = bytes;
  		min_bytes = fs_info->sectorsize;
  	} else {
  		cont1_bytes = max(bytes, (bytes + empty_size) >> 2);
  		min_bytes = fs_info->sectorsize;
  	}
  
  	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 < 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;
  	}
  
  	trace_btrfs_find_cluster(block_group, offset, bytes, empty_size,
  				 min_bytes);
  
  	ret = setup_cluster_no_bitmap(block_group, cluster, &bitmaps, offset,
  				      bytes + empty_size,
  				      cont1_bytes, min_bytes);
  	if (ret)
  		ret = setup_cluster_bitmap(block_group, cluster, &bitmaps,
  					   offset, bytes + empty_size,
  					   cont1_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;
  	} else {
  		trace_btrfs_failed_cluster_setup(block_group);
  	}
  out:
  	spin_unlock(&cluster->lock);
  	spin_unlock(&ctl->tree_lock);
  
  	return ret;
  }
  
  /*
   * simple code to zero out a cluster
   */
  void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
  {
  	spin_lock_init(&cluster->lock);
  	spin_lock_init(&cluster->refill_lock);
  	cluster->root = RB_ROOT;
  	cluster->max_size = 0;
  	cluster->fragmented = false;
  	INIT_LIST_HEAD(&cluster->block_group_list);
  	cluster->block_group = NULL;
  }
  
  static int do_trimming(struct btrfs_block_group_cache *block_group,
  		       u64 *total_trimmed, u64 start, u64 bytes,
  		       u64 reserved_start, u64 reserved_bytes,
  		       struct btrfs_trim_range *trim_entry)
  {
  	struct btrfs_space_info *space_info = block_group->space_info;
  	struct btrfs_fs_info *fs_info = block_group->fs_info;
  	struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
  	int ret;
  	int update = 0;
  	u64 trimmed = 0;
  
  	spin_lock(&space_info->lock);
  	spin_lock(&block_group->lock);
  	if (!block_group->ro) {
  		block_group->reserved += reserved_bytes;
  		space_info->bytes_reserved += reserved_bytes;
  		update = 1;
  	}
  	spin_unlock(&block_group->lock);
  	spin_unlock(&space_info->lock);
  
  	ret = btrfs_discard_extent(fs_info, start, bytes, &trimmed);
  	if (!ret)
  		*total_trimmed += trimmed;
  
  	mutex_lock(&ctl->cache_writeout_mutex);
  	btrfs_add_free_space(block_group, reserved_start, reserved_bytes);
  	list_del(&trim_entry->list);
  	mutex_unlock(&ctl->cache_writeout_mutex);
  
  	if (update) {
  		spin_lock(&space_info->lock);
  		spin_lock(&block_group->lock);
  		if (block_group->ro)
  			space_info->bytes_readonly += reserved_bytes;
  		block_group->reserved -= reserved_bytes;
  		space_info->bytes_reserved -= reserved_bytes;
  		spin_unlock(&space_info->lock);
  		spin_unlock(&block_group->lock);
  	}
  
  	return ret;
  }
  
  static int trim_no_bitmap(struct btrfs_block_group_cache *block_group,
  			  u64 *total_trimmed, u64 start, u64 end, u64 minlen)
  {
  	struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
  	struct btrfs_free_space *entry;
  	struct rb_node *node;
  	int ret = 0;
  	u64 extent_start;
  	u64 extent_bytes;
  	u64 bytes;
  
  	while (start < end) {
  		struct btrfs_trim_range trim_entry;
  
  		mutex_lock(&ctl->cache_writeout_mutex);
  		spin_lock(&ctl->tree_lock);
  
  		if (ctl->free_space < minlen) {
  			spin_unlock(&ctl->tree_lock);
  			mutex_unlock(&ctl->cache_writeout_mutex);
  			break;
  		}
  
  		entry = tree_search_offset(ctl, start, 0, 1);
  		if (!entry) {
  			spin_unlock(&ctl->tree_lock);
  			mutex_unlock(&ctl->cache_writeout_mutex);
  			break;
  		}
  
  		/* skip bitmaps */
  		while (entry->bitmap) {
  			node = rb_next(&entry->offset_index);
  			if (!node) {
  				spin_unlock(&ctl->tree_lock);
  				mutex_unlock(&ctl->cache_writeout_mutex);
  				goto out;
  			}
  			entry = rb_entry(node, struct btrfs_free_space,
  					 offset_index);
  		}
  
  		if (entry->offset >= end) {
  			spin_unlock(&ctl->tree_lock);
  			mutex_unlock(&ctl->cache_writeout_mutex);
  			break;
  		}
  
  		extent_start = entry->offset;
  		extent_bytes = entry->bytes;
  		start = max(start, extent_start);
  		bytes = min(extent_start + extent_bytes, end) - start;
  		if (bytes < minlen) {
  			spin_unlock(&ctl->tree_lock);
  			mutex_unlock(&ctl->cache_writeout_mutex);
  			goto next;
  		}
  
  		unlink_free_space(ctl, entry);
  		kmem_cache_free(btrfs_free_space_cachep, entry);
  
  		spin_unlock(&ctl->tree_lock);
  		trim_entry.start = extent_start;
  		trim_entry.bytes = extent_bytes;
  		list_add_tail(&trim_entry.list, &ctl->trimming_ranges);
  		mutex_unlock(&ctl->cache_writeout_mutex);
  
  		ret = do_trimming(block_group, total_trimmed, start, bytes,
  				  extent_start, extent_bytes, &trim_entry);
  		if (ret)
  			break;
  next:
  		start += bytes;
  
  		if (fatal_signal_pending(current)) {
  			ret = -ERESTARTSYS;
  			break;
  		}
  
  		cond_resched();
  	}
  out:
  	return ret;
  }
  
  static int trim_bitmaps(struct btrfs_block_group_cache *block_group,
  			u64 *total_trimmed, u64 start, u64 end, u64 minlen)
  {
  	struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
  	struct btrfs_free_space *entry;
  	int ret = 0;
  	int ret2;
  	u64 bytes;
  	u64 offset = offset_to_bitmap(ctl, start);
  
  	while (offset < end) {
  		bool next_bitmap = false;
  		struct btrfs_trim_range trim_entry;
  
  		mutex_lock(&ctl->cache_writeout_mutex);
  		spin_lock(&ctl->tree_lock);
  
  		if (ctl->free_space < minlen) {
  			spin_unlock(&ctl->tree_lock);
  			mutex_unlock(&ctl->cache_writeout_mutex);
  			break;
  		}
  
  		entry = tree_search_offset(ctl, offset, 1, 0);
  		if (!entry) {
  			spin_unlock(&ctl->tree_lock);
  			mutex_unlock(&ctl->cache_writeout_mutex);
  			next_bitmap = true;
  			goto next;
  		}
  
  		bytes = minlen;
  		ret2 = search_bitmap(ctl, entry, &start, &bytes, false);
  		if (ret2 || start >= end) {
  			spin_unlock(&ctl->tree_lock);
  			mutex_unlock(&ctl->cache_writeout_mutex);
  			next_bitmap = true;
  			goto next;
  		}
  
  		bytes = min(bytes, end - start);
  		if (bytes < minlen) {
  			spin_unlock(&ctl->tree_lock);
  			mutex_unlock(&ctl->cache_writeout_mutex);
  			goto next;
  		}
  
  		bitmap_clear_bits(ctl, entry, start, bytes);
  		if (entry->bytes == 0)
  			free_bitmap(ctl, entry);
  
  		spin_unlock(&ctl->tree_lock);
  		trim_entry.start = start;
  		trim_entry.bytes = bytes;
  		list_add_tail(&trim_entry.list, &ctl->trimming_ranges);
  		mutex_unlock(&ctl->cache_writeout_mutex);
  
  		ret = do_trimming(block_group, total_trimmed, start, bytes,
  				  start, bytes, &trim_entry);
  		if (ret)
  			break;
  next:
  		if (next_bitmap) {
  			offset += BITS_PER_BITMAP * ctl->unit;
  		} else {
  			start += bytes;
  			if (start >= offset + BITS_PER_BITMAP * ctl->unit)
  				offset += BITS_PER_BITMAP * ctl->unit;
  		}
  
  		if (fatal_signal_pending(current)) {
  			ret = -ERESTARTSYS;
  			break;
  		}
  
  		cond_resched();
  	}
  
  	return ret;
  }
  
  void btrfs_get_block_group_trimming(struct btrfs_block_group_cache *cache)
  {
  	atomic_inc(&cache->trimming);
  }
  
  void btrfs_put_block_group_trimming(struct btrfs_block_group_cache *block_group)
  {
  	struct btrfs_fs_info *fs_info = block_group->fs_info;
  	struct extent_map_tree *em_tree;
  	struct extent_map *em;
  	bool cleanup;
  
  	spin_lock(&block_group->lock);
  	cleanup = (atomic_dec_and_test(&block_group->trimming) &&
  		   block_group->removed);
  	spin_unlock(&block_group->lock);
  
  	if (cleanup) {
  		mutex_lock(&fs_info->chunk_mutex);
  		em_tree = &fs_info->mapping_tree.map_tree;
  		write_lock(&em_tree->lock);
  		em = lookup_extent_mapping(em_tree, block_group->key.objectid,
  					   1);
  		BUG_ON(!em); /* logic error, can't happen */
  		/*
  		 * remove_extent_mapping() will delete us from the pinned_chunks
  		 * list, which is protected by the chunk mutex.
  		 */
  		remove_extent_mapping(em_tree, em);
  		write_unlock(&em_tree->lock);
  		mutex_unlock(&fs_info->chunk_mutex);
  
  		/* once for us and once for the tree */
  		free_extent_map(em);
  		free_extent_map(em);
  
  		/*
  		 * We've left one free space entry and other tasks trimming
  		 * this block group have left 1 entry each one. Free them.
  		 */
  		__btrfs_remove_free_space_cache(block_group->free_space_ctl);
  	}
  }
  
  int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
  			   u64 *trimmed, u64 start, u64 end, u64 minlen)
  {
  	int ret;
  
  	*trimmed = 0;
  
  	spin_lock(&block_group->lock);
  	if (block_group->removed) {
  		spin_unlock(&block_group->lock);
  		return 0;
  	}
  	btrfs_get_block_group_trimming(block_group);
  	spin_unlock(&block_group->lock);
  
  	ret = trim_no_bitmap(block_group, trimmed, start, end, minlen);
  	if (ret)
  		goto out;
  
  	ret = trim_bitmaps(block_group, trimmed, start, end, minlen);
  out:
  	btrfs_put_block_group_trimming(block_group);
  	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, true);
  		/* Logic error; Should be empty if it can't find anything */
  		ASSERT(!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->ino_cache_lock);
  	if (root->ino_cache_inode)
  		inode = igrab(root->ino_cache_inode);
  	spin_unlock(&root->ino_cache_lock);
  	if (inode)
  		return inode;
  
  	inode = __lookup_free_space_inode(root, path, 0);
  	if (IS_ERR(inode))
  		return inode;
  
  	spin_lock(&root->ino_cache_lock);
  	if (!btrfs_fs_closing(root->fs_info))
  		root->ino_cache_inode = igrab(inode);
  	spin_unlock(&root->ino_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(fs_info, 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)
  		btrfs_err(fs_info,
  			"failed to load free ino cache for root %llu",
  			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 inode *inode)
  {
  	struct btrfs_fs_info *fs_info = root->fs_info;
  	struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
  	int ret;
  	struct btrfs_io_ctl io_ctl;
  	bool release_metadata = true;
  
  	if (!btrfs_test_opt(fs_info, INODE_MAP_CACHE))
  		return 0;
  
  	memset(&io_ctl, 0, sizeof(io_ctl));
  	ret = __btrfs_write_out_cache(root, inode, ctl, NULL, &io_ctl, trans);
  	if (!ret) {
  		/*
  		 * At this point writepages() didn't error out, so our metadata
  		 * reservation is released when the writeback finishes, at
  		 * inode.c:btrfs_finish_ordered_io(), regardless of it finishing
  		 * with or without an error.
  		 */
  		release_metadata = false;
  		ret = btrfs_wait_cache_io_root(root, trans, &io_ctl, path);
  	}
  
  	if (ret) {
  		if (release_metadata)
  			btrfs_delalloc_release_metadata(BTRFS_I(inode),
  					inode->i_size);
  #ifdef DEBUG
  		btrfs_err(fs_info,
  			  "failed to write free ino cache for root %llu",
  			  root->root_key.objectid);
  #endif
  	}
  
  	return ret;
  }
  
  #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
  /*
   * Use this if you need to make a bitmap or extent entry specifically, it
   * doesn't do any of the merging that add_free_space does, this acts a lot like
   * how the free space cache loading stuff works, so you can get really weird
   * configurations.
   */
  int test_add_free_space_entry(struct btrfs_block_group_cache *cache,
  			      u64 offset, u64 bytes, bool bitmap)
  {
  	struct btrfs_free_space_ctl *ctl = cache->free_space_ctl;
  	struct btrfs_free_space *info = NULL, *bitmap_info;
  	void *map = NULL;
  	u64 bytes_added;
  	int ret;
  
  again:
  	if (!info) {
  		info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
  		if (!info)
  			return -ENOMEM;
  	}
  
  	if (!bitmap) {
  		spin_lock(&ctl->tree_lock);
  		info->offset = offset;
  		info->bytes = bytes;
  		info->max_extent_size = 0;
  		ret = link_free_space(ctl, info);
  		spin_unlock(&ctl->tree_lock);
  		if (ret)
  			kmem_cache_free(btrfs_free_space_cachep, info);
  		return ret;
  	}
  
  	if (!map) {
  		map = kzalloc(PAGE_SIZE, GFP_NOFS);
  		if (!map) {
  			kmem_cache_free(btrfs_free_space_cachep, info);
  			return -ENOMEM;
  		}
  	}
  
  	spin_lock(&ctl->tree_lock);
  	bitmap_info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
  					 1, 0);
  	if (!bitmap_info) {
  		info->bitmap = map;
  		map = NULL;
  		add_new_bitmap(ctl, info, offset);
  		bitmap_info = info;
  		info = NULL;
  	}
  
  	bytes_added = add_bytes_to_bitmap(ctl, bitmap_info, offset, bytes);
  
  	bytes -= bytes_added;
  	offset += bytes_added;
  	spin_unlock(&ctl->tree_lock);
  
  	if (bytes)
  		goto again;
  
  	if (info)
  		kmem_cache_free(btrfs_free_space_cachep, info);
  	if (map)
  		kfree(map);
  	return 0;
  }
  
  /*
   * Checks to see if the given range is in the free space cache.  This is really
   * just used to check the absence of space, so if there is free space in the
   * range at all we will return 1.
   */
  int test_check_exists(struct btrfs_block_group_cache *cache,
  		      u64 offset, u64 bytes)
  {
  	struct btrfs_free_space_ctl *ctl = cache->free_space_ctl;
  	struct btrfs_free_space *info;
  	int ret = 0;
  
  	spin_lock(&ctl->tree_lock);
  	info = tree_search_offset(ctl, offset, 0, 0);
  	if (!info) {
  		info = tree_search_offset(ctl, offset_to_bitmap(ctl, offset),
  					  1, 0);
  		if (!info)
  			goto out;
  	}
  
  have_info:
  	if (info->bitmap) {
  		u64 bit_off, bit_bytes;
  		struct rb_node *n;
  		struct btrfs_free_space *tmp;
  
  		bit_off = offset;
  		bit_bytes = ctl->unit;
  		ret = search_bitmap(ctl, info, &bit_off, &bit_bytes, false);
  		if (!ret) {
  			if (bit_off == offset) {
  				ret = 1;
  				goto out;
  			} else if (bit_off > offset &&
  				   offset + bytes > bit_off) {
  				ret = 1;
  				goto out;
  			}
  		}
  
  		n = rb_prev(&info->offset_index);
  		while (n) {
  			tmp = rb_entry(n, struct btrfs_free_space,
  				       offset_index);
  			if (tmp->offset + tmp->bytes < offset)
  				break;
  			if (offset + bytes < tmp->offset) {
  				n = rb_prev(&tmp->offset_index);
  				continue;
  			}
  			info = tmp;
  			goto have_info;
  		}
  
  		n = rb_next(&info->offset_index);
  		while (n) {
  			tmp = rb_entry(n, struct btrfs_free_space,
  				       offset_index);
  			if (offset + bytes < tmp->offset)
  				break;
  			if (tmp->offset + tmp->bytes < offset) {
  				n = rb_next(&tmp->offset_index);
  				continue;
  			}
  			info = tmp;
  			goto have_info;
  		}
  
  		ret = 0;
  		goto out;
  	}
  
  	if (info->offset == offset) {
  		ret = 1;
  		goto out;
  	}
  
  	if (offset > info->offset && offset < info->offset + info->bytes)
  		ret = 1;
  out:
  	spin_unlock(&ctl->tree_lock);
  	return ret;
  }
  #endif /* CONFIG_BTRFS_FS_RUN_SANITY_TESTS */
  