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