block/blklogwrites.c

   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_int.h"
  16 #include "qapi/qmp/qdict.h"
  17 #include "qapi/qmp/qstring.h"
  18 #include "qemu/cutils.h"
  19 #include "qemu/option.h"
  20
  21 /* Disk format stuff - taken from Linux drivers/md/dm-log-writes.c */
  22
  23 #define LOG_FLUSH_FLAG   (1 << 0)
  24 #define LOG_FUA_FLAG     (1 << 1)
  25 #define LOG_DISCARD_FLAG (1 << 2)
  26 #define LOG_MARK_FLAG    (1 << 3)
  27 #define LOG_FLAG_MASK    (LOG_FLUSH_FLAG \
  28                          | LOG_FUA_FLAG \
  29                          | LOG_DISCARD_FLAG \
  30                          | LOG_MARK_FLAG)
  31
  32 #define WRITE_LOG_VERSION 1ULL
  33 #define WRITE_LOG_MAGIC 0x6a736677736872ULL
  34
  35 /* All fields are little-endian. */
  36 struct log_write_super {
  37     uint64_t magic;
  38     uint64_t version;
  39     uint64_t nr_entries;
  40     uint32_t sectorsize;
  41 } QEMU_PACKED;
  42
  43 struct log_write_entry {
  44     uint64_t sector;
  45     uint64_t nr_sectors;
  46     uint64_t flags;
  47     uint64_t data_len;
  48 } QEMU_PACKED;
  49
  50 /* End of disk format structures. */
  51
  52 typedef struct {
  53     BdrvChild *log_file;
  54     uint32_t sectorsize;
  55     uint32_t sectorbits;
  56     uint64_t cur_log_sector;
  57     uint64_t nr_entries;
  58     uint64_t update_interval;
  59 } BDRVBlkLogWritesState;
  60
  61 static QemuOptsList runtime_opts = {
  62     .name = "blklogwrites",
  63     .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
  64     .desc = {
  65         {
  66             .name = "log-append",
  67             .type = QEMU_OPT_BOOL,
  68             .help = "Append to an existing log",
  69         },
  70         {
  71             .name = "log-sector-size",
  72             .type = QEMU_OPT_SIZE,
  73             .help = "Log sector size",
  74         },
  75         {
  76             .name = "log-super-update-interval",
  77             .type = QEMU_OPT_NUMBER,
  78             .help = "Log superblock update interval (# of write requests)",
  79         },
  80         { /* end of list */ }
  81     },
  82 };
  83
  84 static inline uint32_t blk_log_writes_log2(uint32_t value)
  85 {
  86     assert(value > 0);
  87     return 31 - clz32(value);
  88 }
  89
  90 static inline bool blk_log_writes_sector_size_valid(uint32_t sector_size)
  91 {
  92     return sector_size < (1ull << 24) && is_power_of_2(sector_size);
  93 }
  94
  95 static uint64_t blk_log_writes_find_cur_log_sector(BdrvChild *log,
  96                                                    uint32_t sector_size,
  97                                                    uint64_t nr_entries,
  98                                                    Error **errp)
  99 {
 100     uint64_t cur_sector = 1;
 101     uint64_t cur_idx = 0;
 102     uint32_t sector_bits = blk_log_writes_log2(sector_size);
 103     struct log_write_entry cur_entry;
 104
 105     while (cur_idx < nr_entries) {
 106         int read_ret = bdrv_pread(log, cur_sector << sector_bits, &cur_entry,
 107                                   sizeof(cur_entry));
 108         if (read_ret < 0) {
 109             error_setg_errno(errp, -read_ret,
 110                              "Failed to read log entry %"PRIu64, cur_idx);
 111             return (uint64_t)-1ull;
 112         }
 113
 114         if (cur_entry.flags & ~cpu_to_le64(LOG_FLAG_MASK)) {
 115             error_setg(errp, "Invalid flags 0x%"PRIx64" in log entry %"PRIu64,
 116                        le64_to_cpu(cur_entry.flags), cur_idx);
 117             return (uint64_t)-1ull;
 118         }
 119
 120         /* Account for the sector of the entry itself */
 121         ++cur_sector;
 122
 123         /*
 124          * Account for the data of the write.
 125          * For discards, this data is not present.
 126          */
 127         if (!(cur_entry.flags & cpu_to_le64(LOG_DISCARD_FLAG))) {
 128             cur_sector += le64_to_cpu(cur_entry.nr_sectors);
 129         }
 130
 131         ++cur_idx;
 132     }
 133
 134     return cur_sector;
 135 }
 136
 137 static int blk_log_writes_open(BlockDriverState *bs, QDict *options, int flags,
 138                                Error **errp)
 139 {
 140     BDRVBlkLogWritesState *s = bs->opaque;
 141     QemuOpts *opts;
 142     Error *local_err = NULL;
 143     int ret;
 144     uint64_t log_sector_size;
 145     bool log_append;
 146
 147     opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
 148     qemu_opts_absorb_qdict(opts, options, &local_err);
 149     if (local_err) {
 150         ret = -EINVAL;
 151         error_propagate(errp, local_err);
 152         goto fail;
 153     }
 154
 155     /* Open the file */
 156     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file, false,
 157                                &local_err);
 158     if (local_err) {
 159         ret = -EINVAL;
 160         error_propagate(errp, local_err);
 161         goto fail;
 162     }
 163
 164     /* Open the log file */
 165     s->log_file = bdrv_open_child(NULL, options, "log", bs, &child_file, false,
 166                                   &local_err);
 167     if (local_err) {
 168         ret = -EINVAL;
 169         error_propagate(errp, local_err);
 170         goto fail;
 171     }
 172
 173     log_append = qemu_opt_get_bool(opts, "log-append", false);
 174
 175     if (log_append) {
 176         struct log_write_super log_sb = { 0, 0, 0, 0 };
 177
 178         if (qemu_opt_find(opts, "log-sector-size")) {
 179             ret = -EINVAL;
 180             error_setg(errp, "log-append and log-sector-size are mutually "
 181                        "exclusive");
 182             goto fail_log;
 183         }
 184
 185         /* Read log superblock or fake one for an empty log */
 186         if (!bdrv_getlength(s->log_file->bs)) {
 187             log_sb.magic      = cpu_to_le64(WRITE_LOG_MAGIC);
 188             log_sb.version    = cpu_to_le64(WRITE_LOG_VERSION);
 189             log_sb.nr_entries = cpu_to_le64(0);
 190             log_sb.sectorsize = cpu_to_le32(BDRV_SECTOR_SIZE);
 191         } else {
 192             ret = bdrv_pread(s->log_file, 0, &log_sb, sizeof(log_sb));
 193             if (ret < 0) {
 194                 error_setg_errno(errp, -ret, "Could not read log superblock");
 195                 goto fail_log;
 196             }
 197         }
 198
 199         if (log_sb.magic != cpu_to_le64(WRITE_LOG_MAGIC)) {
 200             ret = -EINVAL;
 201             error_setg(errp, "Invalid log superblock magic");
 202             goto fail_log;
 203         }
 204
 205         if (log_sb.version != cpu_to_le64(WRITE_LOG_VERSION)) {
 206             ret = -EINVAL;
 207             error_setg(errp, "Unsupported log version %"PRIu64,
 208                        le64_to_cpu(log_sb.version));
 209             goto fail_log;
 210         }
 211
 212         log_sector_size = le32_to_cpu(log_sb.sectorsize);
 213         s->cur_log_sector = 1;
 214         s->nr_entries = 0;
 215
 216         if (blk_log_writes_sector_size_valid(log_sector_size)) {
 217             s->cur_log_sector =
 218                 blk_log_writes_find_cur_log_sector(s->log_file, log_sector_size,
 219                                     le64_to_cpu(log_sb.nr_entries), &local_err);
 220             if (local_err) {
 221                 ret = -EINVAL;
 222                 error_propagate(errp, local_err);
 223                 goto fail_log;
 224             }
 225
 226             s->nr_entries = le64_to_cpu(log_sb.nr_entries);
 227         }
 228     } else {
 229         log_sector_size = qemu_opt_get_size(opts, "log-sector-size",
 230                                             BDRV_SECTOR_SIZE);
 231         s->cur_log_sector = 1;
 232         s->nr_entries = 0;
 233     }
 234
 235     if (!blk_log_writes_sector_size_valid(log_sector_size)) {
 236         ret = -EINVAL;
 237         error_setg(errp, "Invalid log sector size %"PRIu64, log_sector_size);
 238         goto fail_log;
 239     }
 240
 241     s->sectorsize = log_sector_size;
 242     s->sectorbits = blk_log_writes_log2(log_sector_size);
 243     s->update_interval = qemu_opt_get_number(opts, "log-super-update-interval",
 244                                              4096);
 245     if (!s->update_interval) {
 246         ret = -EINVAL;
 247         error_setg(errp, "Invalid log superblock update interval %"PRIu64,
 248                    s->update_interval);
 249         goto fail_log;
 250     }
 251
 252     ret = 0;
 253 fail_log:
 254     if (ret < 0) {
 255         bdrv_unref_child(bs, s->log_file);
 256         s->log_file = NULL;
 257     }
 258 fail:
 259     if (ret < 0) {
 260         bdrv_unref_child(bs, bs->file);
 261         bs->file = NULL;
 262     }
 263     qemu_opts_del(opts);
 264     return ret;
 265 }
 266
 267 static void blk_log_writes_close(BlockDriverState *bs)
 268 {
 269     BDRVBlkLogWritesState *s = bs->opaque;
 270
 271     bdrv_unref_child(bs, s->log_file);
 272     s->log_file = NULL;
 273 }
 274
 275 static int64_t blk_log_writes_getlength(BlockDriverState *bs)
 276 {
 277     return bdrv_getlength(bs->file->bs);
 278 }
 279
 280 static void blk_log_writes_refresh_filename(BlockDriverState *bs,
 281                                             QDict *options)
 282 {
 283     BDRVBlkLogWritesState *s = bs->opaque;
 284
 285     /* bs->file->bs has already been refreshed */
 286     bdrv_refresh_filename(s->log_file->bs);
 287
 288     if (bs->file->bs->full_open_options
 289         && s->log_file->bs->full_open_options)
 290     {
 291         QDict *opts = qdict_new();
 292         qdict_put_str(opts, "driver", "blklogwrites");
 293
 294         qobject_ref(bs->file->bs->full_open_options);
 295         qdict_put_obj(opts, "file", QOBJECT(bs->file->bs->full_open_options));
 296         qobject_ref(s->log_file->bs->full_open_options);
 297         qdict_put_obj(opts, "log",
 298                       QOBJECT(s->log_file->bs->full_open_options));
 299         qdict_put_int(opts, "log-sector-size", s->sectorsize);
 300
 301         bs->full_open_options = opts;
 302     }
 303 }
 304
 305 static void blk_log_writes_child_perm(BlockDriverState *bs, BdrvChild *c,
 306                                       const BdrvChildRole *role,
 307                                       BlockReopenQueue *ro_q,
 308                                       uint64_t perm, uint64_t shrd,
 309                                       uint64_t *nperm, uint64_t *nshrd)
 310 {
 311     if (!c) {
 312         *nperm = perm & DEFAULT_PERM_PASSTHROUGH;
 313         *nshrd = (shrd & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED;
 314         return;
 315     }
 316
 317     if (!strcmp(c->name, "log")) {
 318         bdrv_format_default_perms(bs, c, role, ro_q, perm, shrd, nperm, nshrd);
 319     } else {
 320         bdrv_filter_default_perms(bs, c, role, ro_q, perm, shrd, nperm, nshrd);
 321     }
 322 }
 323
 324 static void blk_log_writes_refresh_limits(BlockDriverState *bs, Error **errp)
 325 {
 326     BDRVBlkLogWritesState *s = bs->opaque;
 327     bs->bl.request_alignment = s->sectorsize;
 328 }
 329
 330 static int coroutine_fn
 331 blk_log_writes_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 332                          QEMUIOVector *qiov, int flags)
 333 {
 334     return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
 335 }
 336
 337 typedef struct BlkLogWritesFileReq {
 338     BlockDriverState *bs;
 339     uint64_t offset;
 340     uint64_t bytes;
 341     int file_flags;
 342     QEMUIOVector *qiov;
 343     int (*func)(struct BlkLogWritesFileReq *r);
 344     int file_ret;
 345 } BlkLogWritesFileReq;
 346
 347 typedef struct {
 348     BlockDriverState *bs;
 349     QEMUIOVector *qiov;
 350     struct log_write_entry entry;
 351     uint64_t zero_size;
 352     int log_ret;
 353 } BlkLogWritesLogReq;
 354
 355 static void coroutine_fn blk_log_writes_co_do_log(BlkLogWritesLogReq *lr)
 356 {
 357     BDRVBlkLogWritesState *s = lr->bs->opaque;
 358     uint64_t cur_log_offset = s->cur_log_sector << s->sectorbits;
 359
 360     s->nr_entries++;
 361     s->cur_log_sector +=
 362             ROUND_UP(lr->qiov->size, s->sectorsize) >> s->sectorbits;
 363
 364     lr->log_ret = bdrv_co_pwritev(s->log_file, cur_log_offset, lr->qiov->size,
 365                                   lr->qiov, 0);
 366
 367     /* Logging for the "write zeroes" operation */
 368     if (lr->log_ret == 0 && lr->zero_size) {
 369         cur_log_offset = s->cur_log_sector << s->sectorbits;
 370         s->cur_log_sector +=
 371                 ROUND_UP(lr->zero_size, s->sectorsize) >> s->sectorbits;
 372
 373         lr->log_ret = bdrv_co_pwrite_zeroes(s->log_file, cur_log_offset,
 374                                             lr->zero_size, 0);
 375     }
 376
 377     /* Update super block on flush or every update interval */
 378     if (lr->log_ret == 0 && ((lr->entry.flags & LOG_FLUSH_FLAG)
 379         || (s->nr_entries % s->update_interval == 0)))
 380     {
 381         struct log_write_super super = {
 382             .magic      = cpu_to_le64(WRITE_LOG_MAGIC),
 383             .version    = cpu_to_le64(WRITE_LOG_VERSION),
 384             .nr_entries = cpu_to_le64(s->nr_entries),
 385             .sectorsize = cpu_to_le32(s->sectorsize),
 386         };
 387         void *zeroes = g_malloc0(s->sectorsize - sizeof(super));
 388         QEMUIOVector qiov;
 389
 390         qemu_iovec_init(&qiov, 2);
 391         qemu_iovec_add(&qiov, &super, sizeof(super));
 392         qemu_iovec_add(&qiov, zeroes, s->sectorsize - sizeof(super));
 393
 394         lr->log_ret =
 395             bdrv_co_pwritev(s->log_file, 0, s->sectorsize, &qiov, 0);
 396         if (lr->log_ret == 0) {
 397             lr->log_ret = bdrv_co_flush(s->log_file->bs);
 398         }
 399         qemu_iovec_destroy(&qiov);
 400         g_free(zeroes);
 401     }
 402 }
 403
 404 static void coroutine_fn blk_log_writes_co_do_file(BlkLogWritesFileReq *fr)
 405 {
 406     fr->file_ret = fr->func(fr);
 407 }
 408
 409 static int coroutine_fn
 410 blk_log_writes_co_log(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 411                       QEMUIOVector *qiov, int flags,
 412                       int (*file_func)(BlkLogWritesFileReq *r),
 413                       uint64_t entry_flags, bool is_zero_write)
 414 {
 415     QEMUIOVector log_qiov;
 416     size_t niov = qiov ? qiov->niov : 0;
 417     BDRVBlkLogWritesState *s = bs->opaque;
 418     BlkLogWritesFileReq fr = {
 419         .bs         = bs,
 420         .offset     = offset,
 421         .bytes      = bytes,
 422         .file_flags = flags,
 423         .qiov       = qiov,
 424         .func       = file_func,
 425     };
 426     BlkLogWritesLogReq lr = {
 427         .bs             = bs,
 428         .qiov           = &log_qiov,
 429         .entry = {
 430             .sector     = cpu_to_le64(offset >> s->sectorbits),
 431             .nr_sectors = cpu_to_le64(bytes >> s->sectorbits),
 432             .flags      = cpu_to_le64(entry_flags),
 433             .data_len   = 0,
 434         },
 435         .zero_size = is_zero_write ? bytes : 0,
 436     };
 437     void *zeroes = g_malloc0(s->sectorsize - sizeof(lr.entry));
 438
 439     assert((1 << s->sectorbits) == s->sectorsize);
 440     assert(bs->bl.request_alignment == s->sectorsize);
 441     assert(QEMU_IS_ALIGNED(offset, bs->bl.request_alignment));
 442     assert(QEMU_IS_ALIGNED(bytes, bs->bl.request_alignment));
 443
 444     qemu_iovec_init(&log_qiov, niov + 2);
 445     qemu_iovec_add(&log_qiov, &lr.entry, sizeof(lr.entry));
 446     qemu_iovec_add(&log_qiov, zeroes, s->sectorsize - sizeof(lr.entry));
 447     if (qiov) {
 448         qemu_iovec_concat(&log_qiov, qiov, 0, qiov->size);
 449     }
 450
 451     blk_log_writes_co_do_file(&fr);
 452     blk_log_writes_co_do_log(&lr);
 453
 454     qemu_iovec_destroy(&log_qiov);
 455     g_free(zeroes);
 456
 457     if (lr.log_ret < 0) {
 458         return lr.log_ret;
 459     }
 460
 461     return fr.file_ret;
 462 }
 463
 464 static int coroutine_fn
 465 blk_log_writes_co_do_file_pwritev(BlkLogWritesFileReq *fr)
 466 {
 467     return bdrv_co_pwritev(fr->bs->file, fr->offset, fr->bytes,
 468                            fr->qiov, fr->file_flags);
 469 }
 470
 471 static int coroutine_fn
 472 blk_log_writes_co_do_file_pwrite_zeroes(BlkLogWritesFileReq *fr)
 473 {
 474     return bdrv_co_pwrite_zeroes(fr->bs->file, fr->offset, fr->bytes,
 475                                  fr->file_flags);
 476 }
 477
 478 static int coroutine_fn blk_log_writes_co_do_file_flush(BlkLogWritesFileReq *fr)
 479 {
 480     return bdrv_co_flush(fr->bs->file->bs);
 481 }
 482
 483 static int coroutine_fn
 484 blk_log_writes_co_do_file_pdiscard(BlkLogWritesFileReq *fr)
 485 {
 486     return bdrv_co_pdiscard(fr->bs->file->bs, fr->offset, fr->bytes);
 487 }
 488
 489 static int coroutine_fn
 490 blk_log_writes_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 491                           QEMUIOVector *qiov, int flags)
 492 {
 493     return blk_log_writes_co_log(bs, offset, bytes, qiov, flags,
 494                                  blk_log_writes_co_do_file_pwritev, 0, false);
 495 }
 496
 497 static int coroutine_fn
 498 blk_log_writes_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int bytes,
 499                                 BdrvRequestFlags flags)
 500 {
 501     return blk_log_writes_co_log(bs, offset, bytes, NULL, flags,
 502                                  blk_log_writes_co_do_file_pwrite_zeroes, 0,
 503                                  true);
 504 }
 505
 506 static int coroutine_fn blk_log_writes_co_flush_to_disk(BlockDriverState *bs)
 507 {
 508     return blk_log_writes_co_log(bs, 0, 0, NULL, 0,
 509                                  blk_log_writes_co_do_file_flush,
 510                                  LOG_FLUSH_FLAG, false);
 511 }
 512
 513 static int coroutine_fn
 514 blk_log_writes_co_pdiscard(BlockDriverState *bs, int64_t offset, int count)
 515 {
 516     return blk_log_writes_co_log(bs, offset, count, NULL, 0,
 517                                  blk_log_writes_co_do_file_pdiscard,
 518                                  LOG_DISCARD_FLAG, false);
 519 }
 520
 521 static BlockDriver bdrv_blk_log_writes = {
 522     .format_name            = "blklogwrites",
 523     .instance_size          = sizeof(BDRVBlkLogWritesState),
 524
 525     .bdrv_open              = blk_log_writes_open,
 526     .bdrv_close             = blk_log_writes_close,
 527     .bdrv_getlength         = blk_log_writes_getlength,
 528     .bdrv_refresh_filename  = blk_log_writes_refresh_filename,
 529     .bdrv_child_perm        = blk_log_writes_child_perm,
 530     .bdrv_refresh_limits    = blk_log_writes_refresh_limits,
 531
 532     .bdrv_co_preadv         = blk_log_writes_co_preadv,
 533     .bdrv_co_pwritev        = blk_log_writes_co_pwritev,
 534     .bdrv_co_pwrite_zeroes  = blk_log_writes_co_pwrite_zeroes,
 535     .bdrv_co_flush_to_disk  = blk_log_writes_co_flush_to_disk,
 536     .bdrv_co_pdiscard       = blk_log_writes_co_pdiscard,
 537     .bdrv_co_block_status   = bdrv_co_block_status_from_file,
 538
 539     .is_filter              = true,
 540 };
 541
 542 static void bdrv_blk_log_writes_init(void)
 543 {
 544     bdrv_register(&bdrv_blk_log_writes);
 545 }
 546
 547 block_init(bdrv_blk_log_writes_init);