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