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/* SPDX-License-Identifier: GPL-2.0 */
* Copyright (C) 2008 Oracle. All rights reserved.
#include <linux/sizes.h>
* We want to make sure that amount of RAM required to uncompress an extent is
* reasonable, so we limit the total size in ram of a compressed extent to
* 128k. This is a crucial number because it also controls how easily we can
* spread reads across cpus for decompression.
* We also want to make sure the amount of IO required to do a random read is
* reasonably small, so we limit the size of a compressed extent to 128k.
/* Maximum length of compressed data stored on disk */
/* Maximum size of data before compression */
struct compressed_bio {
/* number of bios pending for this compressed extent */
refcount_t pending_bios;
/* the pages with the compressed data on them */
struct page **compressed_pages;
/* inode that owns this data */
struct inode *inode;
/* starting offset in the inode for our pages */
u64 start;
/* number of bytes in the inode we're working on */
unsigned long len;
/* number of bytes on disk */
unsigned long compressed_len;
/* the compression algorithm for this bio */
int compress_type;
/* number of compressed pages in the array */
unsigned long nr_pages;
/* IO errors */
int errors;
int mirror_num;
/* for reads, this is the bio we are copying the data into */
struct bio *orig_bio;
* the start of a variable length array of checksums only
* used by reads
u8 sums[];
static inline unsigned int btrfs_compress_type(unsigned int type_level)
return (type_level & 0xF);
static inline unsigned int btrfs_compress_level(unsigned int type_level)
return ((type_level & 0xF0) >> 4);
void __init btrfs_init_compress(void);
void __cold btrfs_exit_compress(void);
int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping,
u64 start, struct page **pages,
unsigned long *out_pages,
unsigned long *total_in,
unsigned long *total_out);
int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
unsigned long start_byte, size_t srclen, size_t destlen);
int btrfs_decompress_buf2page(const char *buf, unsigned long buf_start,
unsigned long total_out, u64 disk_start,
struct bio *bio);
blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start,
unsigned long len, u64 disk_start,
unsigned long compressed_len,
struct page **compressed_pages,
unsigned long nr_pages,
unsigned int write_flags,
struct cgroup_subsys_state *blkcg_css);
blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
int mirror_num, unsigned long bio_flags);
unsigned int btrfs_compress_str2level(unsigned int type, const char *str);
enum btrfs_compression_type {
struct workspace_manager {
struct list_head idle_ws;
spinlock_t ws_lock;
/* Number of free workspaces */
int free_ws;
/* Total number of allocated workspaces */
atomic_t total_ws;
/* Waiters for a free workspace */
wait_queue_head_t ws_wait;
struct list_head *btrfs_get_workspace(int type, unsigned int level);
void btrfs_put_workspace(int type, struct list_head *ws);
struct btrfs_compress_op {
struct workspace_manager *workspace_manager;
/* Maximum level supported by the compression algorithm */
unsigned int max_level;
unsigned int default_level;
/* The heuristic workspaces are managed via the 0th workspace manager */
extern const struct btrfs_compress_op btrfs_heuristic_compress;
extern const struct btrfs_compress_op btrfs_zlib_compress;
extern const struct btrfs_compress_op btrfs_lzo_compress;
extern const struct btrfs_compress_op btrfs_zstd_compress;
const char* btrfs_compress_type2str(enum btrfs_compression_type type);
bool btrfs_compress_is_valid_type(const char *str, size_t len);
unsigned int btrfs_compress_set_level(int type, unsigned level);
int btrfs_compress_heuristic(struct inode *inode, u64 start, u64 end);