linux/fs/btrfs/free-space-cache.h
Li Zefan 581bb05094 Btrfs: Cache free inode numbers in memory
Currently btrfs stores the highest objectid of the fs tree, and it always
returns (highest+1) inode number when we create a file, so inode numbers
won't be reclaimed when we delete files, so we'll run out of inode numbers
as we keep create/delete files in 32bits machines.

This fixes it, and it works similarly to how we cache free space in block
cgroups.

We start a kernel thread to read the file tree. By scanning inode items,
we know which chunks of inode numbers are free, and we cache them in
an rb-tree.

Because we are searching the commit root, we have to carefully handle the
cross-transaction case.

The rb-tree is a hybrid extent+bitmap tree, so if we have too many small
chunks of inode numbers, we'll use bitmaps. Initially we allow 16K ram
of extents, and a bitmap will be used if we exceed this threshold. The
extents threshold is adjusted in runtime.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
2011-04-25 16:46:04 +08:00

103 lines
3.7 KiB
C

/*
* Copyright (C) 2009 Oracle. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#ifndef __BTRFS_FREE_SPACE_CACHE
#define __BTRFS_FREE_SPACE_CACHE
struct btrfs_free_space {
struct rb_node offset_index;
u64 offset;
u64 bytes;
unsigned long *bitmap;
struct list_head list;
};
struct btrfs_free_space_ctl {
spinlock_t tree_lock;
struct rb_root free_space_offset;
u64 free_space;
int extents_thresh;
int free_extents;
int total_bitmaps;
int unit;
u64 start;
struct btrfs_free_space_op *op;
void *private;
};
struct btrfs_free_space_op {
void (*recalc_thresholds)(struct btrfs_free_space_ctl *ctl);
bool (*use_bitmap)(struct btrfs_free_space_ctl *ctl,
struct btrfs_free_space *info);
};
struct inode *lookup_free_space_inode(struct btrfs_root *root,
struct btrfs_block_group_cache
*block_group, struct btrfs_path *path);
int create_free_space_inode(struct btrfs_root *root,
struct btrfs_trans_handle *trans,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path);
int btrfs_truncate_free_space_cache(struct btrfs_root *root,
struct btrfs_trans_handle *trans,
struct btrfs_path *path,
struct inode *inode);
int load_free_space_cache(struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group);
int btrfs_write_out_cache(struct btrfs_root *root,
struct btrfs_trans_handle *trans,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path);
void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group);
int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
u64 bytenr, u64 size);
static inline int
btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
u64 bytenr, u64 size)
{
return __btrfs_add_free_space(block_group->free_space_ctl,
bytenr, size);
}
int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
u64 bytenr, u64 size);
void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl);
void btrfs_remove_free_space_cache(struct btrfs_block_group_cache
*block_group);
u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
u64 offset, u64 bytes, u64 empty_size);
u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root);
void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
u64 bytes);
int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_block_group_cache *block_group,
struct btrfs_free_cluster *cluster,
u64 offset, u64 bytes, u64 empty_size);
void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster);
u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
struct btrfs_free_cluster *cluster, u64 bytes,
u64 min_start);
int btrfs_return_cluster_to_free_space(
struct btrfs_block_group_cache *block_group,
struct btrfs_free_cluster *cluster);
int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
u64 *trimmed, u64 start, u64 end, u64 minlen);
#endif