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-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_unref_child(bs, s->log_file);
 255         s->log_file = NULL;
 256     }
 257 fail:
 258     qemu_opts_del(opts);
 259     return ret;
 260 }
 261
 262 static void blk_log_writes_close(BlockDriverState *bs)
 263 {
 264     BDRVBlkLogWritesState *s = bs->opaque;
 265
 266     bdrv_unref_child(bs, s->log_file);
 267     s->log_file = NULL;
 268 }
 269
 270 static int64_t coroutine_fn GRAPH_RDLOCK
 271 blk_log_writes_co_getlength(BlockDriverState *bs)
 272 {
 273     return bdrv_co_getlength(bs->file->bs);
 274 }
 275
 276 static void blk_log_writes_child_perm(BlockDriverState *bs, BdrvChild *c,
 277                                       BdrvChildRole role,
 278                                       BlockReopenQueue *ro_q,
 279                                       uint64_t perm, uint64_t shrd,
 280                                       uint64_t *nperm, uint64_t *nshrd)
 281 {
 282     if (!c) {
 283         *nperm = perm & DEFAULT_PERM_PASSTHROUGH;
 284         *nshrd = (shrd & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED;
 285         return;
 286     }
 287
 288     bdrv_default_perms(bs, c, role, ro_q, perm, shrd,
 289                        nperm, nshrd);
 290 }
 291
 292 static void blk_log_writes_refresh_limits(BlockDriverState *bs, Error **errp)
 293 {
 294     BDRVBlkLogWritesState *s = bs->opaque;
 295     bs->bl.request_alignment = s->sectorsize;
 296 }
 297
 298 static int coroutine_fn GRAPH_RDLOCK
 299 blk_log_writes_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
 300                          QEMUIOVector *qiov, BdrvRequestFlags flags)
 301 {
 302     return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
 303 }
 304
 305 typedef struct BlkLogWritesFileReq {
 306     BlockDriverState *bs;
 307     uint64_t offset;
 308     uint64_t bytes;
 309     int file_flags;
 310     QEMUIOVector *qiov;
 311     int GRAPH_RDLOCK_PTR (*func)(struct BlkLogWritesFileReq *r);
 312     int file_ret;
 313 } BlkLogWritesFileReq;
 314
 315 typedef struct {
 316     BlockDriverState *bs;
 317     QEMUIOVector *qiov;
 318     struct log_write_entry entry;
 319     uint64_t zero_size;
 320     int log_ret;
 321 } BlkLogWritesLogReq;
 322
 323 static void coroutine_fn GRAPH_RDLOCK
 324 blk_log_writes_co_do_log(BlkLogWritesLogReq *lr)
 325 {
 326     BDRVBlkLogWritesState *s = lr->bs->opaque;
 327     uint64_t cur_log_offset = s->cur_log_sector << s->sectorbits;
 328
 329     s->nr_entries++;
 330     s->cur_log_sector +=
 331             ROUND_UP(lr->qiov->size, s->sectorsize) >> s->sectorbits;
 332
 333     lr->log_ret = bdrv_co_pwritev(s->log_file, cur_log_offset, lr->qiov->size,
 334                                   lr->qiov, 0);
 335
 336     /* Logging for the "write zeroes" operation */
 337     if (lr->log_ret == 0 && lr->zero_size) {
 338         cur_log_offset = s->cur_log_sector << s->sectorbits;
 339         s->cur_log_sector +=
 340                 ROUND_UP(lr->zero_size, s->sectorsize) >> s->sectorbits;
 341
 342         lr->log_ret = bdrv_co_pwrite_zeroes(s->log_file, cur_log_offset,
 343                                             lr->zero_size, 0);
 344     }
 345
 346     /* Update super block on flush or every update interval */
 347     if (lr->log_ret == 0 && ((lr->entry.flags & LOG_FLUSH_FLAG)
 348         || (s->nr_entries % s->update_interval == 0)))
 349     {
 350         struct log_write_super super = {
 351             .magic      = cpu_to_le64(WRITE_LOG_MAGIC),
 352             .version    = cpu_to_le64(WRITE_LOG_VERSION),
 353             .nr_entries = cpu_to_le64(s->nr_entries),
 354             .sectorsize = cpu_to_le32(s->sectorsize),
 355         };
 356         void *zeroes = g_malloc0(s->sectorsize - sizeof(super));
 357         QEMUIOVector qiov;
 358
 359         qemu_iovec_init(&qiov, 2);
 360         qemu_iovec_add(&qiov, &super, sizeof(super));
 361         qemu_iovec_add(&qiov, zeroes, s->sectorsize - sizeof(super));
 362
 363         lr->log_ret =
 364             bdrv_co_pwritev(s->log_file, 0, s->sectorsize, &qiov, 0);
 365         if (lr->log_ret == 0) {
 366             lr->log_ret = bdrv_co_flush(s->log_file->bs);
 367         }
 368         qemu_iovec_destroy(&qiov);
 369         g_free(zeroes);
 370     }
 371 }
 372
 373 static void coroutine_fn GRAPH_RDLOCK
 374 blk_log_writes_co_do_file(BlkLogWritesFileReq *fr)
 375 {
 376     fr->file_ret = fr->func(fr);
 377 }
 378
 379 static int coroutine_fn GRAPH_RDLOCK
 380 blk_log_writes_co_log(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 381                       QEMUIOVector *qiov, int flags,
 382                       int /*GRAPH_RDLOCK*/ (*file_func)(BlkLogWritesFileReq *r),
 383                       uint64_t entry_flags, bool is_zero_write)
 384 {
 385     QEMUIOVector log_qiov;
 386     size_t niov = qiov ? qiov->niov : 0;
 387     BDRVBlkLogWritesState *s = bs->opaque;
 388     BlkLogWritesFileReq fr = {
 389         .bs         = bs,
 390         .offset     = offset,
 391         .bytes      = bytes,
 392         .file_flags = flags,
 393         .qiov       = qiov,
 394         .func       = file_func,
 395     };
 396     BlkLogWritesLogReq lr = {
 397         .bs             = bs,
 398         .qiov           = &log_qiov,
 399         .entry = {
 400             .sector     = cpu_to_le64(offset >> s->sectorbits),
 401             .nr_sectors = cpu_to_le64(bytes >> s->sectorbits),
 402             .flags      = cpu_to_le64(entry_flags),
 403             .data_len   = 0,
 404         },
 405         .zero_size = is_zero_write ? bytes : 0,
 406     };
 407     void *zeroes = g_malloc0(s->sectorsize - sizeof(lr.entry));
 408
 409     assert((1 << s->sectorbits) == s->sectorsize);
 410     assert(bs->bl.request_alignment == s->sectorsize);
 411     assert(QEMU_IS_ALIGNED(offset, bs->bl.request_alignment));
 412     assert(QEMU_IS_ALIGNED(bytes, bs->bl.request_alignment));
 413
 414     qemu_iovec_init(&log_qiov, niov + 2);
 415     qemu_iovec_add(&log_qiov, &lr.entry, sizeof(lr.entry));
 416     qemu_iovec_add(&log_qiov, zeroes, s->sectorsize - sizeof(lr.entry));
 417     if (qiov) {
 418         qemu_iovec_concat(&log_qiov, qiov, 0, qiov->size);
 419     }
 420
 421     blk_log_writes_co_do_file(&fr);
 422     blk_log_writes_co_do_log(&lr);
 423
 424     qemu_iovec_destroy(&log_qiov);
 425     g_free(zeroes);
 426
 427     if (lr.log_ret < 0) {
 428         return lr.log_ret;
 429     }
 430
 431     return fr.file_ret;
 432 }
 433
 434 static int coroutine_fn GRAPH_RDLOCK
 435 blk_log_writes_co_do_file_pwritev(BlkLogWritesFileReq *fr)
 436 {
 437     return bdrv_co_pwritev(fr->bs->file, fr->offset, fr->bytes,
 438                            fr->qiov, fr->file_flags);
 439 }
 440
 441 static int coroutine_fn GRAPH_RDLOCK
 442 blk_log_writes_co_do_file_pwrite_zeroes(BlkLogWritesFileReq *fr)
 443 {
 444     return bdrv_co_pwrite_zeroes(fr->bs->file, fr->offset, fr->bytes,
 445                                  fr->file_flags);
 446 }
 447
 448 static int coroutine_fn GRAPH_RDLOCK
 449 blk_log_writes_co_do_file_flush(BlkLogWritesFileReq *fr)
 450 {
 451     return bdrv_co_flush(fr->bs->file->bs);
 452 }
 453
 454 static int coroutine_fn GRAPH_RDLOCK
 455 blk_log_writes_co_do_file_pdiscard(BlkLogWritesFileReq *fr)
 456 {
 457     return bdrv_co_pdiscard(fr->bs->file, fr->offset, fr->bytes);
 458 }
 459
 460 static int coroutine_fn GRAPH_RDLOCK
 461 blk_log_writes_co_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes,
 462                           QEMUIOVector *qiov, BdrvRequestFlags flags)
 463 {
 464     return blk_log_writes_co_log(bs, offset, bytes, qiov, flags,
 465                                  blk_log_writes_co_do_file_pwritev, 0, false);
 466 }
 467
 468 static int coroutine_fn GRAPH_RDLOCK
 469 blk_log_writes_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
 470                                 int64_t bytes, BdrvRequestFlags flags)
 471 {
 472     return blk_log_writes_co_log(bs, offset, bytes, NULL, flags,
 473                                  blk_log_writes_co_do_file_pwrite_zeroes, 0,
 474                                  true);
 475 }
 476
 477 static int coroutine_fn GRAPH_RDLOCK
 478 blk_log_writes_co_flush_to_disk(BlockDriverState *bs)
 479 {
 480     return blk_log_writes_co_log(bs, 0, 0, NULL, 0,
 481                                  blk_log_writes_co_do_file_flush,
 482                                  LOG_FLUSH_FLAG, false);
 483 }
 484
 485 static int coroutine_fn GRAPH_RDLOCK
 486 blk_log_writes_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes)
 487 {
 488     return blk_log_writes_co_log(bs, offset, bytes, NULL, 0,
 489                                  blk_log_writes_co_do_file_pdiscard,
 490                                  LOG_DISCARD_FLAG, false);
 491 }
 492
 493 static const char *const blk_log_writes_strong_runtime_opts[] = {
 494     "log-append",
 495     "log-sector-size",
 496
 497     NULL
 498 };
 499
 500 static BlockDriver bdrv_blk_log_writes = {
 501     .format_name            = "blklogwrites",
 502     .instance_size          = sizeof(BDRVBlkLogWritesState),
 503
 504     .bdrv_open              = blk_log_writes_open,
 505     .bdrv_close             = blk_log_writes_close,
 506     .bdrv_co_getlength      = blk_log_writes_co_getlength,
 507     .bdrv_child_perm        = blk_log_writes_child_perm,
 508     .bdrv_refresh_limits    = blk_log_writes_refresh_limits,
 509
 510     .bdrv_co_preadv         = blk_log_writes_co_preadv,
 511     .bdrv_co_pwritev        = blk_log_writes_co_pwritev,
 512     .bdrv_co_pwrite_zeroes  = blk_log_writes_co_pwrite_zeroes,
 513     .bdrv_co_flush_to_disk  = blk_log_writes_co_flush_to_disk,
 514     .bdrv_co_pdiscard       = blk_log_writes_co_pdiscard,
 515
 516     .is_filter              = true,
 517     .strong_runtime_opts    = blk_log_writes_strong_runtime_opts,
 518 };
 519
 520 static void bdrv_blk_log_writes_init(void)
 521 {
 522     bdrv_register(&bdrv_blk_log_writes);
 523 }
 524
 525 block_init(bdrv_blk_log_writes_init);