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