dm-dirty-log.h

  1/* SPDX-License-Identifier: GPL-2.0-only */
  2/*
  3 * Copyright (C) 2003 Sistina Software
  4 * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
  5 *
  6 * Device-Mapper dirty region log.
  7 *
  8 * This file is released under the LGPL.
  9 */
 10
 11#ifndef _LINUX_DM_DIRTY_LOG
 12#define _LINUX_DM_DIRTY_LOG
 13
 14#ifdef __KERNEL__
 15
 16#include <linux/types.h>
 17#include <linux/device-mapper.h>
 18
 19typedef sector_t region_t;
 20
 21struct dm_dirty_log_type;
 22
 23struct dm_dirty_log {
 24	struct dm_dirty_log_type *type;
 25	int (*flush_callback_fn)(struct dm_target *ti);
 26	void *context;
 27};
 28
 29struct dm_dirty_log_type {
 30	const char *name;
 31	struct module *module;
 32
 33	/* For internal device-mapper use */
 34	struct list_head list;
 35
 36	int (*ctr)(struct dm_dirty_log *log, struct dm_target *ti,
 37		   unsigned int argc, char **argv);
 38	void (*dtr)(struct dm_dirty_log *log);
 39
 40	/*
 41	 * There are times when we don't want the log to touch
 42	 * the disk.
 43	 */
 44	int (*presuspend)(struct dm_dirty_log *log);
 45	int (*postsuspend)(struct dm_dirty_log *log);
 46	int (*resume)(struct dm_dirty_log *log);
 47
 48	/*
 49	 * Retrieves the smallest size of region that the log can
 50	 * deal with.
 51	 */
 52	uint32_t (*get_region_size)(struct dm_dirty_log *log);
 53
 54	/*
 55	 * A predicate to say whether a region is clean or not.
 56	 * May block.
 57	 */
 58	int (*is_clean)(struct dm_dirty_log *log, region_t region);
 59
 60	/*
 61	 *  Returns: 0, 1, -EWOULDBLOCK, < 0
 62	 *
 63	 * A predicate function to check the area given by
 64	 * [sector, sector + len) is in sync.
 65	 *
 66	 * If -EWOULDBLOCK is returned the state of the region is
 67	 * unknown, typically this will result in a read being
 68	 * passed to a daemon to deal with, since a daemon is
 69	 * allowed to block.
 70	 */
 71	int (*in_sync)(struct dm_dirty_log *log, region_t region,
 72		       int can_block);
 73
 74	/*
 75	 * Flush the current log state (eg, to disk).  This
 76	 * function may block.
 77	 */
 78	int (*flush)(struct dm_dirty_log *log);
 79
 80	/*
 81	 * Mark an area as clean or dirty.  These functions may
 82	 * block, though for performance reasons blocking should
 83	 * be extremely rare (eg, allocating another chunk of
 84	 * memory for some reason).
 85	 */
 86	void (*mark_region)(struct dm_dirty_log *log, region_t region);
 87	void (*clear_region)(struct dm_dirty_log *log, region_t region);
 88
 89	/*
 90	 * Returns: <0 (error), 0 (no region), 1 (region)
 91	 *
 92	 * The mirrord will need perform recovery on regions of
 93	 * the mirror that are in the NOSYNC state.  This
 94	 * function asks the log to tell the caller about the
 95	 * next region that this machine should recover.
 96	 *
 97	 * Do not confuse this function with 'in_sync()', one
 98	 * tells you if an area is synchronised, the other
 99	 * assigns recovery work.
100	 */
101	int (*get_resync_work)(struct dm_dirty_log *log, region_t *region);
102
103	/*
104	 * This notifies the log that the resync status of a region
105	 * has changed.  It also clears the region from the recovering
106	 * list (if present).
107	 */
108	void (*set_region_sync)(struct dm_dirty_log *log,
109				region_t region, int in_sync);
110
111	/*
112	 * Returns the number of regions that are in sync.
113	 */
114	region_t (*get_sync_count)(struct dm_dirty_log *log);
115
116	/*
117	 * Support function for mirror status requests.
118	 */
119	int (*status)(struct dm_dirty_log *log, status_type_t status_type,
120		      char *result, unsigned int maxlen);
121
122	/*
123	 * is_remote_recovering is necessary for cluster mirroring. It provides
124	 * a way to detect recovery on another node, so we aren't writing
125	 * concurrently.  This function is likely to block (when a cluster log
126	 * is used).
127	 *
128	 * Returns: 0, 1
129	 */
130	int (*is_remote_recovering)(struct dm_dirty_log *log, region_t region);
131};
132
133int dm_dirty_log_type_register(struct dm_dirty_log_type *type);
134int dm_dirty_log_type_unregister(struct dm_dirty_log_type *type);
135
136/*
137 * Make sure you use these two functions, rather than calling
138 * type->constructor/destructor() directly.
139 */
140struct dm_dirty_log *dm_dirty_log_create(const char *type_name,
141			struct dm_target *ti,
142			int (*flush_callback_fn)(struct dm_target *ti),
143			unsigned int argc, char **argv);
144void dm_dirty_log_destroy(struct dm_dirty_log *log);
145
146#endif	/* __KERNEL__ */
147#endif	/* _LINUX_DM_DIRTY_LOG_H */