include/linux/dm-dirty-log.h

Source file repositories/reference/linux-study-clean/include/linux/dm-dirty-log.h

File Facts

System
Linux kernel
Corpus path
include/linux/dm-dirty-log.h
Extension
.h
Size
4095 bytes
Lines
148
Domain
Core OS
Bucket
Core Kernel Interface
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 dm_dirty_log {
	struct dm_dirty_log_type *type;
	int (*flush_callback_fn)(struct dm_target *ti);
	void *context;
};

struct dm_dirty_log_type {
	const char *name;
	struct module *module;

	/* For internal device-mapper use */
	struct list_head list;

	int (*ctr)(struct dm_dirty_log *log, struct dm_target *ti,
		   unsigned int argc, char **argv);
	void (*dtr)(struct dm_dirty_log *log);

	/*
	 * There are times when we don't want the log to touch
	 * the disk.
	 */
	int (*presuspend)(struct dm_dirty_log *log);
	int (*postsuspend)(struct dm_dirty_log *log);
	int (*resume)(struct dm_dirty_log *log);

	/*
	 * Retrieves the smallest size of region that the log can
	 * deal with.
	 */
	uint32_t (*get_region_size)(struct dm_dirty_log *log);

	/*
	 * A predicate to say whether a region is clean or not.
	 * May block.
	 */
	int (*is_clean)(struct dm_dirty_log *log, region_t region);

	/*
	 *  Returns: 0, 1, -EWOULDBLOCK, < 0
	 *
	 * A predicate function to check the area given by
	 * [sector, sector + len) is in sync.
	 *
	 * If -EWOULDBLOCK is returned the state of the region is
	 * unknown, typically this will result in a read being
	 * passed to a daemon to deal with, since a daemon is
	 * allowed to block.
	 */
	int (*in_sync)(struct dm_dirty_log *log, region_t region,
		       int can_block);

	/*
	 * Flush the current log state (eg, to disk).  This
	 * function may block.
	 */
	int (*flush)(struct dm_dirty_log *log);

	/*
	 * Mark an area as clean or dirty.  These functions may
	 * block, though for performance reasons blocking should
	 * be extremely rare (eg, allocating another chunk of
	 * memory for some reason).
	 */
	void (*mark_region)(struct dm_dirty_log *log, region_t region);
	void (*clear_region)(struct dm_dirty_log *log, region_t region);

	/*
	 * Returns: <0 (error), 0 (no region), 1 (region)
	 *
	 * The mirrord will need perform recovery on regions of
	 * the mirror that are in the NOSYNC state.  This
	 * function asks the log to tell the caller about the
	 * next region that this machine should recover.
	 *
	 * Do not confuse this function with 'in_sync()', one
	 * tells you if an area is synchronised, the other
	 * assigns recovery work.
	 */
	int (*get_resync_work)(struct dm_dirty_log *log, region_t *region);

	/*
	 * This notifies the log that the resync status of a region
	 * has changed.  It also clears the region from the recovering
	 * list (if present).
	 */
	void (*set_region_sync)(struct dm_dirty_log *log,
				region_t region, int in_sync);

	/*
	 * Returns the number of regions that are in sync.

Annotation

Implementation Notes