/* SPDX-License-Identifier: GPL-2.0 */

  /*
   * Copyright (C) 2008 Oracle.  All rights reserved.

   */

  #ifndef BTRFS_COMPRESSION_H
  #define BTRFS_COMPRESSION_H

  #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 */
  #define BTRFS_MAX_COMPRESSED		(SZ_128K)
  /* Maximum size of data before compression */
  #define BTRFS_MAX_UNCOMPRESSED		(SZ_128K)

  #define	BTRFS_ZLIB_DEFAULT_LEVEL		3

  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);

  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 {
  	BTRFS_COMPRESS_NONE  = 0,
  	BTRFS_COMPRESS_ZLIB  = 1,
  	BTRFS_COMPRESS_LZO   = 2,

  	BTRFS_COMPRESS_ZSTD  = 3,
  	BTRFS_COMPRESS_TYPES = 3,

  };

  struct workspace_manager {
  	const struct btrfs_compress_op *ops;
  	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;
  };
  
  void btrfs_init_workspace_manager(struct workspace_manager *wsm,
  				  const struct btrfs_compress_op *ops);

  struct list_head *btrfs_get_workspace(struct workspace_manager *wsm,
  				      unsigned int level);

  void btrfs_put_workspace(struct workspace_manager *wsm, struct list_head *ws);
  void btrfs_cleanup_workspace_manager(struct workspace_manager *wsm);

  struct btrfs_compress_op {

  	void (*init_workspace_manager)(void);
  
  	void (*cleanup_workspace_manager)(void);

  	struct list_head *(*get_workspace)(unsigned int level);

  
  	void (*put_workspace)(struct list_head *ws);

  	struct list_head *(*alloc_workspace)(unsigned int level);

  
  	void (*free_workspace)(struct list_head *workspace);
  
  	int (*compress_pages)(struct list_head *workspace,
  			      struct address_space *mapping,

  			      u64 start,

  			      struct page **pages,

  			      unsigned long *out_pages,
  			      unsigned long *total_in,

  			      unsigned long *total_out);

  	int (*decompress_bio)(struct list_head *workspace,

  				struct compressed_bio *cb);

  
  	int (*decompress)(struct list_head *workspace,
  			  unsigned char *data_in,
  			  struct page *dest_page,
  			  unsigned long start_byte,
  			  size_t srclen, size_t destlen);

  	/* 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 */
  #define BTRFS_NR_WORKSPACE_MANAGERS	(BTRFS_COMPRESS_TYPES + 1)
  
  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);

  #endif