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