1 /* $NetBSD: dm_target_snapshot.c,v 1.12 2010/01/04 00:12:22 haad Exp $ */ 2 3 /* 4 * Copyright (c) 2008 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Adam Hamsik. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /* 33 * 1. Suspend my_data to temporarily stop any I/O while the snapshot is being 34 * activated. 35 * dmsetup suspend my_data 36 * 37 * 2. Create the snapshot-origin device with no table. 38 * dmsetup create my_data_org 39 * 40 * 3. Read the table from my_data and load it into my_data_org. 41 * dmsetup table my_data | dmsetup load my_data_org 42 * 43 * 4. Resume this new table. 44 * dmsetup resume my_data_org 45 * 46 * 5. Create the snapshot device with no table. 47 * dmsetup create my_data_snap 48 * 49 * 6. Load the table into my_data_snap. This uses /dev/hdd1 as the COW device and 50 * uses a 32kB chunk-size. 51 * echo "0 `blockdev --getsize /dev/mapper/my_data` snapshot \ 52 * /dev/mapper/my_data_org /dev/hdd1 p 64" | dmsetup load my_data_snap 53 * 54 * 7. Reload my_data as a snapshot-origin device that points to my_data_org. 55 * echo "0 `blockdev --getsize /dev/mapper/my_data` snapshot-origin \ 56 * /dev/mapper/my_data_org" | dmsetup load my_data 57 * 58 * 8. Resume the snapshot and origin devices. 59 * dmsetup resume my_data_snap 60 * dmsetup resume my_data 61 * 62 * Before snapshot creation 63 * dev_name; dev table 64 * | my_data; 0 1024 linear /dev/sd1a 384| 65 * 66 * After snapshot creation 67 * |my_data_org;0 1024 linear /dev/sd1a 384| 68 * / 69 * |my_data; 0 1024 snapshot-origin /dev/vg00/my_data_org| 70 * / 71 * |my_data_snap; 0 1024 snapshot /dev/vg00/my_data /dev/mapper/my_data_cow P 8 72 * \ 73 * |my_data_cow; 0 256 linear /dev/sd1a 1408| 74 */ 75 76 /* 77 * This file implements initial version of device-mapper snapshot target. 78 */ 79 #include <sys/kmem.h> 80 81 #include <dev/disk/dm/dm.h> 82 83 typedef struct target_snapshot_config { 84 dm_pdev_t *tsc_snap_dev; 85 /* cow dev is set only for persistent snapshot devices */ 86 dm_pdev_t *tsc_cow_dev; 87 88 uint64_t tsc_chunk_size; 89 uint32_t tsc_persistent_dev; 90 } dm_target_snapshot_config_t; 91 92 typedef struct target_snapshot_origin_config { 93 dm_pdev_t *tsoc_real_dev; 94 /* list of snapshots ? */ 95 } dm_target_snapshot_origin_config_t; 96 97 int dm_target_snapshot_init(dm_table_entry_t *, int, char **); 98 char *dm_target_snapshot_table(void *); 99 int dm_target_snapshot_strategy(dm_table_entry_t *, struct buf *); 100 int dm_target_snapshot_destroy(dm_table_entry_t *); 101 102 int dm_target_snapshot_orig_init(dm_table_entry_t *, int, char **); 103 char *dm_target_snapshot_orig_table(void *); 104 int dm_target_snapshot_orig_strategy(dm_table_entry_t *, struct buf *); 105 int dm_target_snapshot_orig_destroy(dm_table_entry_t *); 106 107 /* 108 * Init function called from dm_table_load_ioctl. 109 * argv: /dev/mapper/my_data_org /dev/mapper/tsc_cow_dev p 64 110 * snapshot_origin device, cow device, persistent flag, chunk size 111 */ 112 int 113 dm_target_snapshot_init(dm_table_entry_t *table_en, int argc, char **argv) 114 { 115 dm_target_snapshot_config_t *tsc; 116 dm_pdev_t *dmp_snap, *dmp_cow; 117 118 dmp_cow = NULL; 119 120 kprintf("Snapshot target init function called!!\n"); 121 kprintf("Snapshotted device: %s, cow device %s,\n\t persistent flag: %s, " 122 "chunk size: %s\n", argv[0], argv[1], argv[2], argv[3]); 123 124 /* Insert snap device to global pdev list */ 125 if ((dmp_snap = dm_pdev_insert(argv[0])) == NULL) 126 return ENOENT; 127 128 if ((tsc = kmem_alloc(sizeof(dm_target_snapshot_config_t), KM_NOSLEEP)) 129 == NULL) 130 return 1; 131 132 tsc->tsc_persistent_dev = 0; 133 134 /* There is now cow device for nonpersistent snapshot devices */ 135 if (strcmp(argv[2], "p") == 0) { 136 tsc->tsc_persistent_dev = 1; 137 138 /* Insert cow device to global pdev list */ 139 if ((dmp_cow = dm_pdev_insert(argv[1])) == NULL) 140 return ENOENT; 141 } 142 tsc->tsc_chunk_size = atoi64(argv[3]); 143 144 tsc->tsc_snap_dev = dmp_snap; 145 tsc->tsc_cow_dev = dmp_cow; 146 147 dm_table_add_deps(table_en, dmp_snap); 148 dm_table_add_deps(table_en, dmp_cow); 149 150 dm_table_init_target(table_en, tsc); 151 152 return 0; 153 } 154 155 /* 156 * Table routine is called to get params string, which is target 157 * specific. When dm_table_status_ioctl is called with flag 158 * DM_STATUS_TABLE_FLAG I have to sent params string back. 159 */ 160 char * 161 dm_target_snapshot_table(void *target_config) 162 { 163 dm_target_snapshot_config_t *tsc; 164 165 uint32_t i; 166 uint32_t count; 167 size_t prm_len, cow_len; 168 char *params, *cow_name; 169 170 tsc = target_config; 171 172 prm_len = 0; 173 cow_len = 0; 174 count = 0; 175 cow_name = NULL; 176 177 kprintf("Snapshot target table function called\n"); 178 179 /* count number of chars in offset */ 180 for (i = tsc->tsc_chunk_size; i != 0; i /= 10) 181 count++; 182 183 if (tsc->tsc_persistent_dev) 184 cow_len = strlen(tsc->tsc_cow_dev->name); 185 186 /* length of names + count of chars + spaces and null char */ 187 prm_len = strlen(tsc->tsc_snap_dev->name) + cow_len + count + 5; 188 189 params = dm_alloc_string(prm_len); 190 191 kprintf("%s %s %s %" PRIu64 "\n", tsc->tsc_snap_dev->name, 192 tsc->tsc_cow_dev->name, tsc->tsc_persistent_dev ? "p" : "n", 193 tsc->tsc_chunk_size); 194 195 ksnprintf(params, prm_len, "%s %s %s %" PRIu64, tsc->tsc_snap_dev->name, 196 tsc->tsc_persistent_dev ? tsc->tsc_cow_dev->name : "", 197 tsc->tsc_persistent_dev ? "p" : "n", 198 tsc->tsc_chunk_size); 199 200 return params; 201 } 202 203 /* Strategy routine called from dm_strategy. */ 204 int 205 dm_target_snapshot_strategy(dm_table_entry_t *table_en, struct buf *bp) 206 { 207 208 kprintf("Snapshot target read function called!!\n"); 209 210 bp->b_error = EIO; 211 bp->b_resid = 0; 212 213 biodone(bp); 214 215 return 0; 216 } 217 218 /* Doesn't do anything here. */ 219 int 220 dm_target_snapshot_destroy(dm_table_entry_t *table_en) 221 { 222 dm_target_snapshot_config_t *tsc; 223 224 /* 225 * Destroy function is called for every target even if it 226 * doesn't have target_config. 227 */ 228 229 if (table_en->target_config == NULL) 230 return 0; 231 232 kprintf("Snapshot target destroy function called\n"); 233 234 tsc = table_en->target_config; 235 236 /* Decrement pdev ref counter if 0 remove it */ 237 dm_pdev_decr(tsc->tsc_snap_dev); 238 239 if (tsc->tsc_persistent_dev) 240 dm_pdev_decr(tsc->tsc_cow_dev); 241 242 kmem_free(table_en->target_config, sizeof(dm_target_snapshot_config_t)); 243 244 return 0; 245 } 246 247 /* 248 * dm target snapshot origin routines. 249 * 250 * Keep for compatibility with linux lvm2tools. They use two targets 251 * to implement snapshots. Snapshot target will implement exception 252 * store and snapshot origin will implement device which calls every 253 * snapshot device when write is done on master device. 254 */ 255 256 /* 257 * Init function called from dm_table_load_ioctl. 258 * 259 * argv: /dev/mapper/my_data_real 260 */ 261 int 262 dm_target_snapshot_orig_init(dm_table_entry_t *table_en, int argc, char **argv) 263 { 264 dm_target_snapshot_origin_config_t *tsoc; 265 dm_pdev_t *dmp_real; 266 267 kprintf("Snapshot origin target init function called!!\n"); 268 kprintf("Parent device: %s\n", argv[0]); 269 270 /* Insert snap device to global pdev list */ 271 if ((dmp_real = dm_pdev_insert(argv[0])) == NULL) 272 return ENOENT; 273 274 if ((tsoc = kmem_alloc(sizeof(dm_target_snapshot_origin_config_t), KM_NOSLEEP)) 275 == NULL) 276 return 1; 277 278 tsoc->tsoc_real_dev = dmp_real; 279 280 dm_table_add_deps(table_en, dmp_real); 281 282 dm_table_init_target(table_en, tsoc); 283 284 return 0; 285 } 286 287 /* 288 * Table routine is called to get params string, which is target 289 * specific. When dm_table_status_ioctl is called with flag 290 * DM_STATUS_TABLE_FLAG I have to sent params string back. 291 */ 292 char * 293 dm_target_snapshot_orig_table(void *target_config) 294 { 295 dm_target_snapshot_origin_config_t *tsoc; 296 297 size_t prm_len; 298 char *params; 299 300 tsoc = target_config; 301 302 prm_len = 0; 303 304 kprintf("Snapshot origin target table function called\n"); 305 306 /* length of names + count of chars + spaces and null char */ 307 prm_len = strlen(tsoc->tsoc_real_dev->name) + 1; 308 309 kprintf("real_dev name %s\n", tsoc->tsoc_real_dev->name); 310 311 if ((params = kmem_alloc(prm_len, KM_NOSLEEP)) == NULL) 312 return NULL; 313 314 kprintf("%s\n", tsoc->tsoc_real_dev->name); 315 316 snprintf(params, prm_len, "%s", tsoc->tsoc_real_dev->name); 317 318 return params; 319 } 320 321 /* Strategy routine called from dm_strategy. */ 322 int 323 dm_target_snapshot_orig_strategy(dm_table_entry_t *table_en, struct buf *bp) 324 { 325 326 kprintf("Snapshot_Orig target read function called!!\n"); 327 328 bp->b_error = EIO; 329 bp->b_resid = 0; 330 331 biodone(bp); 332 333 return 0; 334 } 335 336 /* Decrement pdev and free allocated space. */ 337 int 338 dm_target_snapshot_orig_destroy(dm_table_entry_t *table_en) 339 { 340 dm_target_snapshot_origin_config_t *tsoc; 341 342 /* 343 * Destroy function is called for every target even if it 344 * doesn't have target_config. 345 */ 346 347 if (table_en->target_config == NULL) 348 return 0; 349 350 tsoc = table_en->target_config; 351 352 /* Decrement pdev ref counter if 0 remove it */ 353 dm_pdev_decr(tsoc->tsoc_real_dev); 354 355 /* Unbusy target so we can unload it */ 356 dm_target_unbusy(table_en->target); 357 358 kmem_free(table_en->target_config, sizeof(dm_target_snapshot_origin_config_t)); 359 360 return 0; 361 } 362