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