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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 (*presuspend)(struct dirty_log *log);

        int (*postsuspend)(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 status of a region

         * has changed.  It also clears the region from the recovering

         * list (if present).

         */

        void (*set_region_sync)(struct dirty_log *log,

                                region_t region, int in_sync);

        /*

         * 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