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/*
* Copyright (C) 2003 Sistina Software
*
* This file is released under the LGPL.
*/
#ifndef DM_DIRTY_LOG
#define DM_DIRTY_LOG
#include "dm.h"
typedef sector_t region_t;
struct dirty_log_type;
struct dirty_log {
struct dirty_log_type *type;
void *context;
};
struct dirty_log_type {
struct list_head list;
const char *name;
struct module *module;
unsigned int use_count;
int (*ctr)(struct dirty_log *log, struct dm_target *ti,
unsigned int argc, char **argv);
void (*dtr)(struct dirty_log *log);
/*
* There are times when we don't want the log to touch
* the disk.
*/
int (*suspend)(struct dirty_log *log);
int (*resume)(struct dirty_log *log);
/*
* Retrieves the smallest size of region that the log can
* deal with.
*/
uint32_t (*get_region_size)(struct dirty_log *log);
/*
* A predicate to say whether a region is clean or not.
* May block.
*/
int (*is_clean)(struct 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 dirty_log *log, region_t region, int can_block);
/*
* Flush the current log state (eg, to disk). This
* function may block.
*/
int (*flush)(struct 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 dirty_log *log, region_t region);
void (*clear_region)(struct 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 dirty_log *log, region_t *region);
/*
* This notifies the log that the resync of an area has
* been completed. The log should then mark this region
* as CLEAN.
*/
void (*complete_resync_work)(struct dirty_log *log,
region_t region, int success);
/*
* Returns the number of regions that are in sync.
*/
region_t (*get_sync_count)(struct dirty_log *log);
/*
* Support function for mirror status requests.
*/
int (*status)(struct dirty_log *log, status_type_t status_type,
char *result, unsigned int maxlen);
};
int dm_register_dirty_log_type(struct dirty_log_type *type);
int dm_unregister_dirty_log_type(struct dirty_log_type *type);
/*
* Make sure you use these two functions, rather than calling
* type->constructor/destructor() directly.
*/
struct dirty_log *dm_create_dirty_log(const char *type_name, struct dm_target *ti,
unsigned int argc, char **argv);
void dm_destroy_dirty_log(struct dirty_log *log);
/*
* init/exit functions.
*/
int dm_dirty_log_init(void);
void dm_dirty_log_exit(void);
#endif
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