1 /* 2 * Write logging blk driver based on blkverify and blkdebug. 3 * 4 * Copyright (c) 2017 Tuomas Tynkkynen <tuomas@tuxera.com> 5 * Copyright (c) 2018 Aapo Vienamo <aapo@tuxera.com> 6 * Copyright (c) 2018 Ari Sundholm <ari@tuxera.com> 7 * 8 * This work is licensed under the terms of the GNU GPL, version 2 or later. 9 * See the COPYING file in the top-level directory. 10 */ 11 12 #include "qemu/osdep.h" 13 #include "qapi/error.h" 14 #include "qemu/sockets.h" /* for EINPROGRESS on Windows */ 15 #include "block/block-io.h" 16 #include "block/block_int.h" 17 #include "qapi/qmp/qdict.h" 18 #include "qapi/qmp/qstring.h" 19 #include "qemu/cutils.h" 20 #include "qemu/module.h" 21 #include "qemu/option.h" 22 23 /* Disk format stuff - taken from Linux drivers/md/dm-log-writes.c */ 24 25 #define LOG_FLUSH_FLAG (1 << 0) 26 #define LOG_FUA_FLAG (1 << 1) 27 #define LOG_DISCARD_FLAG (1 << 2) 28 #define LOG_MARK_FLAG (1 << 3) 29 #define LOG_FLAG_MASK (LOG_FLUSH_FLAG \ 30 | LOG_FUA_FLAG \ 31 | LOG_DISCARD_FLAG \ 32 | LOG_MARK_FLAG) 33 34 #define WRITE_LOG_VERSION 1ULL 35 #define WRITE_LOG_MAGIC 0x6a736677736872ULL 36 37 /* All fields are little-endian. */ 38 struct log_write_super { 39 uint64_t magic; 40 uint64_t version; 41 uint64_t nr_entries; 42 uint32_t sectorsize; 43 } QEMU_PACKED; 44 45 struct log_write_entry { 46 uint64_t sector; 47 uint64_t nr_sectors; 48 uint64_t flags; 49 uint64_t data_len; 50 } QEMU_PACKED; 51 52 /* End of disk format structures. */ 53 54 typedef struct { 55 BdrvChild *log_file; 56 uint32_t sectorsize; 57 uint32_t sectorbits; 58 uint64_t cur_log_sector; 59 uint64_t nr_entries; 60 uint64_t update_interval; 61 } BDRVBlkLogWritesState; 62 63 static QemuOptsList runtime_opts = { 64 .name = "blklogwrites", 65 .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head), 66 .desc = { 67 { 68 .name = "log-append", 69 .type = QEMU_OPT_BOOL, 70 .help = "Append to an existing log", 71 }, 72 { 73 .name = "log-sector-size", 74 .type = QEMU_OPT_SIZE, 75 .help = "Log sector size", 76 }, 77 { 78 .name = "log-super-update-interval", 79 .type = QEMU_OPT_NUMBER, 80 .help = "Log superblock update interval (# of write requests)", 81 }, 82 { /* end of list */ } 83 }, 84 }; 85 86 static inline uint32_t blk_log_writes_log2(uint32_t value) 87 { 88 assert(value > 0); 89 return 31 - clz32(value); 90 } 91 92 static inline bool blk_log_writes_sector_size_valid(uint32_t sector_size) 93 { 94 return is_power_of_2(sector_size) && 95 sector_size >= sizeof(struct log_write_super) && 96 sector_size >= sizeof(struct log_write_entry) && 97 sector_size < (1ull << 24); 98 } 99 100 static uint64_t blk_log_writes_find_cur_log_sector(BdrvChild *log, 101 uint32_t sector_size, 102 uint64_t nr_entries, 103 Error **errp) 104 { 105 uint64_t cur_sector = 1; 106 uint64_t cur_idx = 0; 107 uint32_t sector_bits = blk_log_writes_log2(sector_size); 108 struct log_write_entry cur_entry; 109 110 while (cur_idx < nr_entries) { 111 int read_ret = bdrv_pread(log, cur_sector << sector_bits, 112 sizeof(cur_entry), &cur_entry, 0); 113 if (read_ret < 0) { 114 error_setg_errno(errp, -read_ret, 115 "Failed to read log entry %"PRIu64, cur_idx); 116 return (uint64_t)-1ull; 117 } 118 119 if (cur_entry.flags & ~cpu_to_le64(LOG_FLAG_MASK)) { 120 error_setg(errp, "Invalid flags 0x%"PRIx64" in log entry %"PRIu64, 121 le64_to_cpu(cur_entry.flags), cur_idx); 122 return (uint64_t)-1ull; 123 } 124 125 /* Account for the sector of the entry itself */ 126 ++cur_sector; 127 128 /* 129 * Account for the data of the write. 130 * For discards, this data is not present. 131 */ 132 if (!(cur_entry.flags & cpu_to_le64(LOG_DISCARD_FLAG))) { 133 cur_sector += le64_to_cpu(cur_entry.nr_sectors); 134 } 135 136 ++cur_idx; 137 } 138 139 return cur_sector; 140 } 141 142 static int blk_log_writes_open(BlockDriverState *bs, QDict *options, int flags, 143 Error **errp) 144 { 145 BDRVBlkLogWritesState *s = bs->opaque; 146 QemuOpts *opts; 147 Error *local_err = NULL; 148 int ret; 149 uint64_t log_sector_size; 150 bool log_append; 151 152 opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort); 153 if (!qemu_opts_absorb_qdict(opts, options, errp)) { 154 ret = -EINVAL; 155 goto fail; 156 } 157 158 /* Open the file */ 159 ret = bdrv_open_file_child(NULL, options, "file", bs, errp); 160 if (ret < 0) { 161 goto fail; 162 } 163 164 /* Open the log file */ 165 s->log_file = bdrv_open_child(NULL, options, "log", bs, &child_of_bds, 166 BDRV_CHILD_METADATA, false, errp); 167 if (!s->log_file) { 168 ret = -EINVAL; 169 goto fail; 170 } 171 172 log_append = qemu_opt_get_bool(opts, "log-append", false); 173 174 if (log_append) { 175 struct log_write_super log_sb = { 0, 0, 0, 0 }; 176 177 if (qemu_opt_find(opts, "log-sector-size")) { 178 ret = -EINVAL; 179 error_setg(errp, "log-append and log-sector-size are mutually " 180 "exclusive"); 181 goto fail_log; 182 } 183 184 /* Read log superblock or fake one for an empty log */ 185 if (!bdrv_getlength(s->log_file->bs)) { 186 log_sb.magic = cpu_to_le64(WRITE_LOG_MAGIC); 187 log_sb.version = cpu_to_le64(WRITE_LOG_VERSION); 188 log_sb.nr_entries = cpu_to_le64(0); 189 log_sb.sectorsize = cpu_to_le32(BDRV_SECTOR_SIZE); 190 } else { 191 ret = bdrv_pread(s->log_file, 0, sizeof(log_sb), &log_sb, 0); 192 if (ret < 0) { 193 error_setg_errno(errp, -ret, "Could not read log superblock"); 194 goto fail_log; 195 } 196 } 197 198 if (log_sb.magic != cpu_to_le64(WRITE_LOG_MAGIC)) { 199 ret = -EINVAL; 200 error_setg(errp, "Invalid log superblock magic"); 201 goto fail_log; 202 } 203 204 if (log_sb.version != cpu_to_le64(WRITE_LOG_VERSION)) { 205 ret = -EINVAL; 206 error_setg(errp, "Unsupported log version %"PRIu64, 207 le64_to_cpu(log_sb.version)); 208 goto fail_log; 209 } 210 211 log_sector_size = le32_to_cpu(log_sb.sectorsize); 212 s->cur_log_sector = 1; 213 s->nr_entries = 0; 214 215 if (blk_log_writes_sector_size_valid(log_sector_size)) { 216 s->cur_log_sector = 217 blk_log_writes_find_cur_log_sector(s->log_file, log_sector_size, 218 le64_to_cpu(log_sb.nr_entries), &local_err); 219 if (local_err) { 220 ret = -EINVAL; 221 error_propagate(errp, local_err); 222 goto fail_log; 223 } 224 225 s->nr_entries = le64_to_cpu(log_sb.nr_entries); 226 } 227 } else { 228 log_sector_size = qemu_opt_get_size(opts, "log-sector-size", 229 BDRV_SECTOR_SIZE); 230 s->cur_log_sector = 1; 231 s->nr_entries = 0; 232 } 233 234 if (!blk_log_writes_sector_size_valid(log_sector_size)) { 235 ret = -EINVAL; 236 error_setg(errp, "Invalid log sector size %"PRIu64, log_sector_size); 237 goto fail_log; 238 } 239 240 s->sectorsize = log_sector_size; 241 s->sectorbits = blk_log_writes_log2(log_sector_size); 242 s->update_interval = qemu_opt_get_number(opts, "log-super-update-interval", 243 4096); 244 if (!s->update_interval) { 245 ret = -EINVAL; 246 error_setg(errp, "Invalid log superblock update interval %"PRIu64, 247 s->update_interval); 248 goto fail_log; 249 } 250 251 ret = 0; 252 fail_log: 253 if (ret < 0) { 254 bdrv_graph_wrlock(); 255 bdrv_unref_child(bs, s->log_file); 256 bdrv_graph_wrunlock(); 257 s->log_file = NULL; 258 } 259 fail: 260 qemu_opts_del(opts); 261 return ret; 262 } 263 264 static void blk_log_writes_close(BlockDriverState *bs) 265 { 266 BDRVBlkLogWritesState *s = bs->opaque; 267 268 bdrv_graph_wrlock(); 269 bdrv_unref_child(bs, s->log_file); 270 s->log_file = NULL; 271 bdrv_graph_wrunlock(); 272 } 273 274 static int64_t coroutine_fn GRAPH_RDLOCK 275 blk_log_writes_co_getlength(BlockDriverState *bs) 276 { 277 return bdrv_co_getlength(bs->file->bs); 278 } 279 280 static void blk_log_writes_child_perm(BlockDriverState *bs, BdrvChild *c, 281 BdrvChildRole role, 282 BlockReopenQueue *ro_q, 283 uint64_t perm, uint64_t shrd, 284 uint64_t *nperm, uint64_t *nshrd) 285 { 286 if (!c) { 287 *nperm = perm & DEFAULT_PERM_PASSTHROUGH; 288 *nshrd = (shrd & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED; 289 return; 290 } 291 292 bdrv_default_perms(bs, c, role, ro_q, perm, shrd, 293 nperm, nshrd); 294 } 295 296 static void blk_log_writes_refresh_limits(BlockDriverState *bs, Error **errp) 297 { 298 BDRVBlkLogWritesState *s = bs->opaque; 299 bs->bl.request_alignment = s->sectorsize; 300 } 301 302 static int coroutine_fn GRAPH_RDLOCK 303 blk_log_writes_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes, 304 QEMUIOVector *qiov, BdrvRequestFlags flags) 305 { 306 return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags); 307 } 308 309 typedef struct BlkLogWritesFileReq { 310 BlockDriverState *bs; 311 uint64_t offset; 312 uint64_t bytes; 313 int file_flags; 314 QEMUIOVector *qiov; 315 int GRAPH_RDLOCK_PTR (*func)(struct BlkLogWritesFileReq *r); 316 int file_ret; 317 } BlkLogWritesFileReq; 318 319 typedef struct { 320 BlockDriverState *bs; 321 QEMUIOVector *qiov; 322 struct log_write_entry entry; 323 uint64_t zero_size; 324 int log_ret; 325 } BlkLogWritesLogReq; 326 327 static void coroutine_fn GRAPH_RDLOCK 328 blk_log_writes_co_do_log(BlkLogWritesLogReq *lr) 329 { 330 BDRVBlkLogWritesState *s = lr->bs->opaque; 331 uint64_t cur_log_offset = s->cur_log_sector << s->sectorbits; 332 333 s->nr_entries++; 334 s->cur_log_sector += 335 ROUND_UP(lr->qiov->size, s->sectorsize) >> s->sectorbits; 336 337 lr->log_ret = bdrv_co_pwritev(s->log_file, cur_log_offset, lr->qiov->size, 338 lr->qiov, 0); 339 340 /* Logging for the "write zeroes" operation */ 341 if (lr->log_ret == 0 && lr->zero_size) { 342 cur_log_offset = s->cur_log_sector << s->sectorbits; 343 s->cur_log_sector += 344 ROUND_UP(lr->zero_size, s->sectorsize) >> s->sectorbits; 345 346 lr->log_ret = bdrv_co_pwrite_zeroes(s->log_file, cur_log_offset, 347 lr->zero_size, 0); 348 } 349 350 /* Update super block on flush or every update interval */ 351 if (lr->log_ret == 0 && ((lr->entry.flags & LOG_FLUSH_FLAG) 352 || (s->nr_entries % s->update_interval == 0))) 353 { 354 struct log_write_super super = { 355 .magic = cpu_to_le64(WRITE_LOG_MAGIC), 356 .version = cpu_to_le64(WRITE_LOG_VERSION), 357 .nr_entries = cpu_to_le64(s->nr_entries), 358 .sectorsize = cpu_to_le32(s->sectorsize), 359 }; 360 void *zeroes = g_malloc0(s->sectorsize - sizeof(super)); 361 QEMUIOVector qiov; 362 363 qemu_iovec_init(&qiov, 2); 364 qemu_iovec_add(&qiov, &super, sizeof(super)); 365 qemu_iovec_add(&qiov, zeroes, s->sectorsize - sizeof(super)); 366 367 lr->log_ret = 368 bdrv_co_pwritev(s->log_file, 0, s->sectorsize, &qiov, 0); 369 if (lr->log_ret == 0) { 370 lr->log_ret = bdrv_co_flush(s->log_file->bs); 371 } 372 qemu_iovec_destroy(&qiov); 373 g_free(zeroes); 374 } 375 } 376 377 static void coroutine_fn GRAPH_RDLOCK 378 blk_log_writes_co_do_file(BlkLogWritesFileReq *fr) 379 { 380 fr->file_ret = fr->func(fr); 381 } 382 383 static int coroutine_fn GRAPH_RDLOCK 384 blk_log_writes_co_log(BlockDriverState *bs, uint64_t offset, uint64_t bytes, 385 QEMUIOVector *qiov, int flags, 386 int /*GRAPH_RDLOCK*/ (*file_func)(BlkLogWritesFileReq *r), 387 uint64_t entry_flags, bool is_zero_write) 388 { 389 QEMUIOVector log_qiov; 390 size_t niov = qiov ? qiov->niov : 0; 391 BDRVBlkLogWritesState *s = bs->opaque; 392 BlkLogWritesFileReq fr = { 393 .bs = bs, 394 .offset = offset, 395 .bytes = bytes, 396 .file_flags = flags, 397 .qiov = qiov, 398 .func = file_func, 399 }; 400 BlkLogWritesLogReq lr = { 401 .bs = bs, 402 .qiov = &log_qiov, 403 .entry = { 404 .sector = cpu_to_le64(offset >> s->sectorbits), 405 .nr_sectors = cpu_to_le64(bytes >> s->sectorbits), 406 .flags = cpu_to_le64(entry_flags), 407 .data_len = 0, 408 }, 409 .zero_size = is_zero_write ? bytes : 0, 410 }; 411 void *zeroes = g_malloc0(s->sectorsize - sizeof(lr.entry)); 412 413 assert((1 << s->sectorbits) == s->sectorsize); 414 assert(bs->bl.request_alignment == s->sectorsize); 415 assert(QEMU_IS_ALIGNED(offset, bs->bl.request_alignment)); 416 assert(QEMU_IS_ALIGNED(bytes, bs->bl.request_alignment)); 417 418 qemu_iovec_init(&log_qiov, niov + 2); 419 qemu_iovec_add(&log_qiov, &lr.entry, sizeof(lr.entry)); 420 qemu_iovec_add(&log_qiov, zeroes, s->sectorsize - sizeof(lr.entry)); 421 if (qiov) { 422 qemu_iovec_concat(&log_qiov, qiov, 0, qiov->size); 423 } 424 425 blk_log_writes_co_do_file(&fr); 426 blk_log_writes_co_do_log(&lr); 427 428 qemu_iovec_destroy(&log_qiov); 429 g_free(zeroes); 430 431 if (lr.log_ret < 0) { 432 return lr.log_ret; 433 } 434 435 return fr.file_ret; 436 } 437 438 static int coroutine_fn GRAPH_RDLOCK 439 blk_log_writes_co_do_file_pwritev(BlkLogWritesFileReq *fr) 440 { 441 return bdrv_co_pwritev(fr->bs->file, fr->offset, fr->bytes, 442 fr->qiov, fr->file_flags); 443 } 444 445 static int coroutine_fn GRAPH_RDLOCK 446 blk_log_writes_co_do_file_pwrite_zeroes(BlkLogWritesFileReq *fr) 447 { 448 return bdrv_co_pwrite_zeroes(fr->bs->file, fr->offset, fr->bytes, 449 fr->file_flags); 450 } 451 452 static int coroutine_fn GRAPH_RDLOCK 453 blk_log_writes_co_do_file_flush(BlkLogWritesFileReq *fr) 454 { 455 return bdrv_co_flush(fr->bs->file->bs); 456 } 457 458 static int coroutine_fn GRAPH_RDLOCK 459 blk_log_writes_co_do_file_pdiscard(BlkLogWritesFileReq *fr) 460 { 461 return bdrv_co_pdiscard(fr->bs->file, fr->offset, fr->bytes); 462 } 463 464 static int coroutine_fn GRAPH_RDLOCK 465 blk_log_writes_co_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes, 466 QEMUIOVector *qiov, BdrvRequestFlags flags) 467 { 468 return blk_log_writes_co_log(bs, offset, bytes, qiov, flags, 469 blk_log_writes_co_do_file_pwritev, 0, false); 470 } 471 472 static int coroutine_fn GRAPH_RDLOCK 473 blk_log_writes_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, 474 int64_t bytes, BdrvRequestFlags flags) 475 { 476 return blk_log_writes_co_log(bs, offset, bytes, NULL, flags, 477 blk_log_writes_co_do_file_pwrite_zeroes, 0, 478 true); 479 } 480 481 static int coroutine_fn GRAPH_RDLOCK 482 blk_log_writes_co_flush_to_disk(BlockDriverState *bs) 483 { 484 return blk_log_writes_co_log(bs, 0, 0, NULL, 0, 485 blk_log_writes_co_do_file_flush, 486 LOG_FLUSH_FLAG, false); 487 } 488 489 static int coroutine_fn GRAPH_RDLOCK 490 blk_log_writes_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes) 491 { 492 return blk_log_writes_co_log(bs, offset, bytes, NULL, 0, 493 blk_log_writes_co_do_file_pdiscard, 494 LOG_DISCARD_FLAG, false); 495 } 496 497 static const char *const blk_log_writes_strong_runtime_opts[] = { 498 "log-append", 499 "log-sector-size", 500 501 NULL 502 }; 503 504 static BlockDriver bdrv_blk_log_writes = { 505 .format_name = "blklogwrites", 506 .instance_size = sizeof(BDRVBlkLogWritesState), 507 508 .bdrv_open = blk_log_writes_open, 509 .bdrv_close = blk_log_writes_close, 510 .bdrv_co_getlength = blk_log_writes_co_getlength, 511 .bdrv_child_perm = blk_log_writes_child_perm, 512 .bdrv_refresh_limits = blk_log_writes_refresh_limits, 513 514 .bdrv_co_preadv = blk_log_writes_co_preadv, 515 .bdrv_co_pwritev = blk_log_writes_co_pwritev, 516 .bdrv_co_pwrite_zeroes = blk_log_writes_co_pwrite_zeroes, 517 .bdrv_co_flush_to_disk = blk_log_writes_co_flush_to_disk, 518 .bdrv_co_pdiscard = blk_log_writes_co_pdiscard, 519 520 .is_filter = true, 521 .strong_runtime_opts = blk_log_writes_strong_runtime_opts, 522 }; 523 524 static void bdrv_blk_log_writes_init(void) 525 { 526 bdrv_register(&bdrv_blk_log_writes); 527 } 528 529 block_init(bdrv_blk_log_writes_init); 530