dm-dirty-log.h
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/*
* Copyright (C) 2003 Sistina Software
* Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
*
* Device-Mapper dirty region log.
*
* This file is released under the LGPL.
*/
#ifndef _LINUX_DM_DIRTY_LOG
#define _LINUX_DM_DIRTY_LOG
#ifdef __KERNEL__
#include <linux/types.h>
#include <linux/device-mapper.h>
typedef sector_t region_t;
struct dm_dirty_log_type;
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 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.
*/
region_t (*get_sync_count)(struct dm_dirty_log *log);
/*
* Support function for mirror status requests.
*/
int (*status)(struct dm_dirty_log *log, status_type_t status_type,
char *result, unsigned maxlen);
/*
* is_remote_recovering is necessary for cluster mirroring. It provides
* a way to detect recovery on another node, so we aren't writing
* concurrently. This function is likely to block (when a cluster log
* is used).
*
* Returns: 0, 1
*/
int (*is_remote_recovering)(struct dm_dirty_log *log, region_t region);
};
int dm_dirty_log_type_register(struct dm_dirty_log_type *type);
int dm_dirty_log_type_unregister(struct dm_dirty_log_type *type);
/*
* Make sure you use these two functions, rather than calling
* type->constructor/destructor() directly.
*/
struct dm_dirty_log *dm_dirty_log_create(const char *type_name,
struct dm_target *ti,
int (*flush_callback_fn)(struct dm_target *ti),
unsigned argc, char **argv);
void dm_dirty_log_destroy(struct dm_dirty_log *log);
#endif /* __KERNEL__ */
#endif /* _LINUX_DM_DIRTY_LOG_H */