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     qemu_opts_absorb_qdict(opts, options, &local_err);
 153     if (local_err) {
 154         ret = -EINVAL;
 155         error_propagate(errp, local_err);
 156         goto fail;
 157     }
 158
 159     /* Open the file */
 160     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
 161                                BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY, false,
 162                                &local_err);
 163     if (local_err) {
 164         ret = -EINVAL;
 165         error_propagate(errp, local_err);
 166         goto fail;
 167     }
 168
 169     /* Open the log file */
 170     s->log_file = bdrv_open_child(NULL, options, "log", bs, &child_of_bds,
 171                                   BDRV_CHILD_METADATA, false, &local_err);
 172     if (local_err) {
 173         ret = -EINVAL;
 174         error_propagate(errp, local_err);
 175         goto fail;
 176     }
 177
 178     log_append = qemu_opt_get_bool(opts, "log-append", false);
 179
 180     if (log_append) {
 181         struct log_write_super log_sb = { 0, 0, 0, 0 };
 182
 183         if (qemu_opt_find(opts, "log-sector-size")) {
 184             ret = -EINVAL;
 185             error_setg(errp, "log-append and log-sector-size are mutually "
 186                        "exclusive");
 187             goto fail_log;
 188         }
 189
 190         /* Read log superblock or fake one for an empty log */
 191         if (!bdrv_getlength(s->log_file->bs)) {
 192             log_sb.magic      = cpu_to_le64(WRITE_LOG_MAGIC);
 193             log_sb.version    = cpu_to_le64(WRITE_LOG_VERSION);
 194             log_sb.nr_entries = cpu_to_le64(0);
 195             log_sb.sectorsize = cpu_to_le32(BDRV_SECTOR_SIZE);
 196         } else {
 197             ret = bdrv_pread(s->log_file, 0, &log_sb, sizeof(log_sb));
 198             if (ret < 0) {
 199                 error_setg_errno(errp, -ret, "Could not read log superblock");
 200                 goto fail_log;
 201             }
 202         }
 203
 204         if (log_sb.magic != cpu_to_le64(WRITE_LOG_MAGIC)) {
 205             ret = -EINVAL;
 206             error_setg(errp, "Invalid log superblock magic");
 207             goto fail_log;
 208         }
 209
 210         if (log_sb.version != cpu_to_le64(WRITE_LOG_VERSION)) {
 211             ret = -EINVAL;
 212             error_setg(errp, "Unsupported log version %"PRIu64,
 213                        le64_to_cpu(log_sb.version));
 214             goto fail_log;
 215         }
 216
 217         log_sector_size = le32_to_cpu(log_sb.sectorsize);
 218         s->cur_log_sector = 1;
 219         s->nr_entries = 0;
 220
 221         if (blk_log_writes_sector_size_valid(log_sector_size)) {
 222             s->cur_log_sector =
 223                 blk_log_writes_find_cur_log_sector(s->log_file, log_sector_size,
 224                                     le64_to_cpu(log_sb.nr_entries), &local_err);
 225             if (local_err) {
 226                 ret = -EINVAL;
 227                 error_propagate(errp, local_err);
 228                 goto fail_log;
 229             }
 230
 231             s->nr_entries = le64_to_cpu(log_sb.nr_entries);
 232         }
 233     } else {
 234         log_sector_size = qemu_opt_get_size(opts, "log-sector-size",
 235                                             BDRV_SECTOR_SIZE);
 236         s->cur_log_sector = 1;
 237         s->nr_entries = 0;
 238     }
 239
 240     if (!blk_log_writes_sector_size_valid(log_sector_size)) {
 241         ret = -EINVAL;
 242         error_setg(errp, "Invalid log sector size %"PRIu64, log_sector_size);
 243         goto fail_log;
 244     }
 245
 246     s->sectorsize = log_sector_size;
 247     s->sectorbits = blk_log_writes_log2(log_sector_size);
 248     s->update_interval = qemu_opt_get_number(opts, "log-super-update-interval",
 249                                              4096);
 250     if (!s->update_interval) {
 251         ret = -EINVAL;
 252         error_setg(errp, "Invalid log superblock update interval %"PRIu64,
 253                    s->update_interval);
 254         goto fail_log;
 255     }
 256
 257     ret = 0;
 258 fail_log:
 259     if (ret < 0) {
 260         bdrv_unref_child(bs, s->log_file);
 261         s->log_file = NULL;
 262     }
 263 fail:
 264     if (ret < 0) {
 265         bdrv_unref_child(bs, bs->file);
 266         bs->file = NULL;
 267     }
 268     qemu_opts_del(opts);
 269     return ret;
 270 }
 271
 272 static void blk_log_writes_close(BlockDriverState *bs)
 273 {
 274     BDRVBlkLogWritesState *s = bs->opaque;
 275
 276     bdrv_unref_child(bs, s->log_file);
 277     s->log_file = NULL;
 278 }
 279
 280 static int64_t blk_log_writes_getlength(BlockDriverState *bs)
 281 {
 282     return bdrv_getlength(bs->file->bs);
 283 }
 284
 285 static void blk_log_writes_child_perm(BlockDriverState *bs, BdrvChild *c,
 286                                       const BdrvChildClass *child_class,
 287                                       BdrvChildRole role,
 288                                       BlockReopenQueue *ro_q,
 289                                       uint64_t perm, uint64_t shrd,
 290                                       uint64_t *nperm, uint64_t *nshrd)
 291 {
 292     if (!c) {
 293         *nperm = perm & DEFAULT_PERM_PASSTHROUGH;
 294         *nshrd = (shrd & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED;
 295         return;
 296     }
 297
 298     bdrv_default_perms(bs, c, child_class, role, ro_q, perm, shrd,
 299                        nperm, nshrd);
 300 }
 301
 302 static void blk_log_writes_refresh_limits(BlockDriverState *bs, Error **errp)
 303 {
 304     BDRVBlkLogWritesState *s = bs->opaque;
 305     bs->bl.request_alignment = s->sectorsize;
 306 }
 307
 308 static int coroutine_fn
 309 blk_log_writes_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 310                          QEMUIOVector *qiov, int flags)
 311 {
 312     return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
 313 }
 314
 315 typedef struct BlkLogWritesFileReq {
 316     BlockDriverState *bs;
 317     uint64_t offset;
 318     uint64_t bytes;
 319     int file_flags;
 320     QEMUIOVector *qiov;
 321     int (*func)(struct BlkLogWritesFileReq *r);
 322     int file_ret;
 323 } BlkLogWritesFileReq;
 324
 325 typedef struct {
 326     BlockDriverState *bs;
 327     QEMUIOVector *qiov;
 328     struct log_write_entry entry;
 329     uint64_t zero_size;
 330     int log_ret;
 331 } BlkLogWritesLogReq;
 332
 333 static void coroutine_fn blk_log_writes_co_do_log(BlkLogWritesLogReq *lr)
 334 {
 335     BDRVBlkLogWritesState *s = lr->bs->opaque;
 336     uint64_t cur_log_offset = s->cur_log_sector << s->sectorbits;
 337
 338     s->nr_entries++;
 339     s->cur_log_sector +=
 340             ROUND_UP(lr->qiov->size, s->sectorsize) >> s->sectorbits;
 341
 342     lr->log_ret = bdrv_co_pwritev(s->log_file, cur_log_offset, lr->qiov->size,
 343                                   lr->qiov, 0);
 344
 345     /* Logging for the "write zeroes" operation */
 346     if (lr->log_ret == 0 && lr->zero_size) {
 347         cur_log_offset = s->cur_log_sector << s->sectorbits;
 348         s->cur_log_sector +=
 349                 ROUND_UP(lr->zero_size, s->sectorsize) >> s->sectorbits;
 350
 351         lr->log_ret = bdrv_co_pwrite_zeroes(s->log_file, cur_log_offset,
 352                                             lr->zero_size, 0);
 353     }
 354
 355     /* Update super block on flush or every update interval */
 356     if (lr->log_ret == 0 && ((lr->entry.flags & LOG_FLUSH_FLAG)
 357         || (s->nr_entries % s->update_interval == 0)))
 358     {
 359         struct log_write_super super = {
 360             .magic      = cpu_to_le64(WRITE_LOG_MAGIC),
 361             .version    = cpu_to_le64(WRITE_LOG_VERSION),
 362             .nr_entries = cpu_to_le64(s->nr_entries),
 363             .sectorsize = cpu_to_le32(s->sectorsize),
 364         };
 365         void *zeroes = g_malloc0(s->sectorsize - sizeof(super));
 366         QEMUIOVector qiov;
 367
 368         qemu_iovec_init(&qiov, 2);
 369         qemu_iovec_add(&qiov, &super, sizeof(super));
 370         qemu_iovec_add(&qiov, zeroes, s->sectorsize - sizeof(super));
 371
 372         lr->log_ret =
 373             bdrv_co_pwritev(s->log_file, 0, s->sectorsize, &qiov, 0);
 374         if (lr->log_ret == 0) {
 375             lr->log_ret = bdrv_co_flush(s->log_file->bs);
 376         }
 377         qemu_iovec_destroy(&qiov);
 378         g_free(zeroes);
 379     }
 380 }
 381
 382 static void coroutine_fn blk_log_writes_co_do_file(BlkLogWritesFileReq *fr)
 383 {
 384     fr->file_ret = fr->func(fr);
 385 }
 386
 387 static int coroutine_fn
 388 blk_log_writes_co_log(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 389                       QEMUIOVector *qiov, int flags,
 390                       int (*file_func)(BlkLogWritesFileReq *r),
 391                       uint64_t entry_flags, bool is_zero_write)
 392 {
 393     QEMUIOVector log_qiov;
 394     size_t niov = qiov ? qiov->niov : 0;
 395     BDRVBlkLogWritesState *s = bs->opaque;
 396     BlkLogWritesFileReq fr = {
 397         .bs         = bs,
 398         .offset     = offset,
 399         .bytes      = bytes,
 400         .file_flags = flags,
 401         .qiov       = qiov,
 402         .func       = file_func,
 403     };
 404     BlkLogWritesLogReq lr = {
 405         .bs             = bs,
 406         .qiov           = &log_qiov,
 407         .entry = {
 408             .sector     = cpu_to_le64(offset >> s->sectorbits),
 409             .nr_sectors = cpu_to_le64(bytes >> s->sectorbits),
 410             .flags      = cpu_to_le64(entry_flags),
 411             .data_len   = 0,
 412         },
 413         .zero_size = is_zero_write ? bytes : 0,
 414     };
 415     void *zeroes = g_malloc0(s->sectorsize - sizeof(lr.entry));
 416
 417     assert((1 << s->sectorbits) == s->sectorsize);
 418     assert(bs->bl.request_alignment == s->sectorsize);
 419     assert(QEMU_IS_ALIGNED(offset, bs->bl.request_alignment));
 420     assert(QEMU_IS_ALIGNED(bytes, bs->bl.request_alignment));
 421
 422     qemu_iovec_init(&log_qiov, niov + 2);
 423     qemu_iovec_add(&log_qiov, &lr.entry, sizeof(lr.entry));
 424     qemu_iovec_add(&log_qiov, zeroes, s->sectorsize - sizeof(lr.entry));
 425     if (qiov) {
 426         qemu_iovec_concat(&log_qiov, qiov, 0, qiov->size);
 427     }
 428
 429     blk_log_writes_co_do_file(&fr);
 430     blk_log_writes_co_do_log(&lr);
 431
 432     qemu_iovec_destroy(&log_qiov);
 433     g_free(zeroes);
 434
 435     if (lr.log_ret < 0) {
 436         return lr.log_ret;
 437     }
 438
 439     return fr.file_ret;
 440 }
 441
 442 static int coroutine_fn
 443 blk_log_writes_co_do_file_pwritev(BlkLogWritesFileReq *fr)
 444 {
 445     return bdrv_co_pwritev(fr->bs->file, fr->offset, fr->bytes,
 446                            fr->qiov, fr->file_flags);
 447 }
 448
 449 static int coroutine_fn
 450 blk_log_writes_co_do_file_pwrite_zeroes(BlkLogWritesFileReq *fr)
 451 {
 452     return bdrv_co_pwrite_zeroes(fr->bs->file, fr->offset, fr->bytes,
 453                                  fr->file_flags);
 454 }
 455
 456 static int coroutine_fn blk_log_writes_co_do_file_flush(BlkLogWritesFileReq *fr)
 457 {
 458     return bdrv_co_flush(fr->bs->file->bs);
 459 }
 460
 461 static int coroutine_fn
 462 blk_log_writes_co_do_file_pdiscard(BlkLogWritesFileReq *fr)
 463 {
 464     return bdrv_co_pdiscard(fr->bs->file, fr->offset, fr->bytes);
 465 }
 466
 467 static int coroutine_fn
 468 blk_log_writes_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 469                           QEMUIOVector *qiov, int flags)
 470 {
 471     return blk_log_writes_co_log(bs, offset, bytes, qiov, flags,
 472                                  blk_log_writes_co_do_file_pwritev, 0, false);
 473 }
 474
 475 static int coroutine_fn
 476 blk_log_writes_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int bytes,
 477                                 BdrvRequestFlags flags)
 478 {
 479     return blk_log_writes_co_log(bs, offset, bytes, NULL, flags,
 480                                  blk_log_writes_co_do_file_pwrite_zeroes, 0,
 481                                  true);
 482 }
 483
 484 static int coroutine_fn blk_log_writes_co_flush_to_disk(BlockDriverState *bs)
 485 {
 486     return blk_log_writes_co_log(bs, 0, 0, NULL, 0,
 487                                  blk_log_writes_co_do_file_flush,
 488                                  LOG_FLUSH_FLAG, false);
 489 }
 490
 491 static int coroutine_fn
 492 blk_log_writes_co_pdiscard(BlockDriverState *bs, int64_t offset, int count)
 493 {
 494     return blk_log_writes_co_log(bs, offset, count, NULL, 0,
 495                                  blk_log_writes_co_do_file_pdiscard,
 496                                  LOG_DISCARD_FLAG, false);
 497 }
 498
 499 static const char *const blk_log_writes_strong_runtime_opts[] = {
 500     "log-append",
 501     "log-sector-size",
 502
 503     NULL
 504 };
 505
 506 static BlockDriver bdrv_blk_log_writes = {
 507     .format_name            = "blklogwrites",
 508     .instance_size          = sizeof(BDRVBlkLogWritesState),
 509
 510     .bdrv_open              = blk_log_writes_open,
 511     .bdrv_close             = blk_log_writes_close,
 512     .bdrv_getlength         = blk_log_writes_getlength,
 513     .bdrv_child_perm        = blk_log_writes_child_perm,
 514     .bdrv_refresh_limits    = blk_log_writes_refresh_limits,
 515
 516     .bdrv_co_preadv         = blk_log_writes_co_preadv,
 517     .bdrv_co_pwritev        = blk_log_writes_co_pwritev,
 518     .bdrv_co_pwrite_zeroes  = blk_log_writes_co_pwrite_zeroes,
 519     .bdrv_co_flush_to_disk  = blk_log_writes_co_flush_to_disk,
 520     .bdrv_co_pdiscard       = blk_log_writes_co_pdiscard,
 521     .bdrv_co_block_status   = bdrv_co_block_status_from_file,
 522
 523     .is_filter              = true,
 524     .strong_runtime_opts    = blk_log_writes_strong_runtime_opts,
 525 };
 526
 527 static void bdrv_blk_log_writes_init(void)
 528 {
 529     bdrv_register(&bdrv_blk_log_writes);
 530 }
 531
 532 block_init(bdrv_blk_log_writes_init);