fs/btrfs/compression.h

Source file repositories/reference/linux-study-clean/fs/btrfs/compression.h

File Facts

System
Linux kernel
Corpus path
fs/btrfs/compression.h
Extension
.h
Size
6543 bytes
Lines
184
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

struct compressed_bio {
	/* starting offset in the inode for our pages */
	u64 start;

	/* Number of bytes in the inode we're working on */
	unsigned int len;

	/* The compression algorithm for this bio */
	u8 compress_type;

	/* Whether this is a write for writeback. */
	bool writeback;

	/* For reads, this is the bio we are copying the data into. */
	struct btrfs_bio *orig_bbio;

	/* Must be last. */
	struct btrfs_bio bbio;
};

static inline struct btrfs_fs_info *cb_to_fs_info(const struct compressed_bio *cb)
{
	return cb->bbio.inode->root->fs_info;
}

/* @range_end must be exclusive. */
static inline u32 btrfs_calc_input_length(struct folio *folio, u64 range_end, u64 cur)
{
	/* @cur must be inside the folio. */
	ASSERT(folio_pos(folio) <= cur);
	ASSERT(cur < folio_next_pos(folio));
	return umin(range_end, folio_next_pos(folio)) - cur;
}

int btrfs_alloc_compress_wsm(struct btrfs_fs_info *fs_info);
void btrfs_free_compress_wsm(struct btrfs_fs_info *fs_info);

int __init btrfs_init_compress(void);
void __cold btrfs_exit_compress(void);

bool btrfs_compress_level_valid(unsigned int type, int level);
int btrfs_decompress(int type, const u8 *data_in, struct folio *dest_folio,
		     unsigned long dest_pgoff, size_t srclen, size_t destlen);
int btrfs_decompress_buf2page(const char *buf, u32 buf_len,
			      struct compressed_bio *cb, u32 decompressed);

struct compressed_bio *btrfs_alloc_compressed_write(struct btrfs_inode *inode,
						    u64 start, u64 len);
void btrfs_submit_compressed_write(struct btrfs_ordered_extent *ordered,
				   struct compressed_bio *cb);
void btrfs_submit_compressed_read(struct btrfs_bio *bbio);

int btrfs_compress_str2level(unsigned int type, const char *str, int *level_ret);

struct folio *btrfs_alloc_compr_folio(struct btrfs_fs_info *fs_info, gfp_t gfp);
void btrfs_free_compr_folio(struct folio *folio);

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(struct btrfs_fs_info *fs_info, int type, int level);
void btrfs_put_workspace(struct btrfs_fs_info *fs_info, int type, struct list_head *ws);

struct btrfs_compress_levels {
	/* Maximum level supported by the compression algorithm */
	int min_level;
	int max_level;
	int default_level;
};

/* The heuristic workspaces are managed via the 0th workspace manager */
#define BTRFS_NR_WORKSPACE_MANAGERS	BTRFS_NR_COMPRESS_TYPES

extern const struct btrfs_compress_levels btrfs_heuristic_compress;
extern const struct btrfs_compress_levels btrfs_zlib_compress;
extern const struct btrfs_compress_levels btrfs_lzo_compress;
extern const struct btrfs_compress_levels 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);

int btrfs_compress_heuristic(struct btrfs_inode *inode, u64 start, u64 end);

Annotation

Implementation Notes