/* * 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; void *context; }; struct dm_dirty_log_type { const char *name; struct module *module; 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); }; 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, unsigned argc, char **argv); void dm_dirty_log_destroy(struct dm_dirty_log *log); #endif /* __KERNEL__ */ #endif /* _LINUX_DM_DIRTY_LOG_H */