text: /*
   * Write logging blk driver based on blkverify and blkdebug.
   *
   * Copyright (c) 2017 Tuomas Tynkkynen <tuomas@tuxera.com>
   * Copyright (c) 2018 Aapo Vienamo <aapo@tuxera.com>
   * Copyright (c) 2018 Ari Sundholm <ari@tuxera.com>
   *
   * This work is licensed under the terms of the GNU GPL, version 2 or later.
   * See the COPYING file in the top-level directory.
   */
  
  #include "qemu/osdep.h"
  #include "qapi/error.h"
  #include "qemu/sockets.h" /* for EINPROGRESS on Windows */
  #include "block/block_int.h"
  #include "qapi/qmp/qdict.h"
  #include "qapi/qmp/qstring.h"
  #include "qemu/cutils.h"
  #include "qemu/module.h"
  #include "qemu/option.h"
  
  /* Disk format stuff - taken from Linux drivers/md/dm-log-writes.c */
  
  #define LOG_FLUSH_FLAG   (1 << 0)
  #define LOG_FUA_FLAG     (1 << 1)
  #define LOG_DISCARD_FLAG (1 << 2)
  #define LOG_MARK_FLAG    (1 << 3)
  #define LOG_FLAG_MASK    (LOG_FLUSH_FLAG \
                           | LOG_FUA_FLAG \
                           | LOG_DISCARD_FLAG \
                           | LOG_MARK_FLAG)
  
  #define WRITE_LOG_VERSION 1ULL
  #define WRITE_LOG_MAGIC 0x6a736677736872ULL
  
  /* All fields are little-endian. */
  struct log_write_super {
      uint64_t magic;
      uint64_t version;
      uint64_t nr_entries;
      uint32_t sectorsize;
  } QEMU_PACKED;
  
  struct log_write_entry {
      uint64_t sector;
      uint64_t nr_sectors;
      uint64_t flags;
      uint64_t data_len;
  } QEMU_PACKED;
  
  /* End of disk format structures. */
  
  typedef struct {
      BdrvChild *log_file;
      uint32_t sectorsize;
      uint32_t sectorbits;
      uint64_t cur_log_sector;
      uint64_t nr_entries;
      uint64_t update_interval;
  } BDRVBlkLogWritesState;
  
  static QemuOptsList runtime_opts = {
      .name = "blklogwrites",
      .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
      .desc = {
          {
              .name = "log-append",
              .type = QEMU_OPT_BOOL,
              .help = "Append to an existing log",
          },
          {
              .name = "log-sector-size",
              .type = QEMU_OPT_SIZE,
              .help = "Log sector size",
          },
          {
              .name = "log-super-update-interval",
              .type = QEMU_OPT_NUMBER,
              .help = "Log superblock update interval (# of write requests)",
          },
          { /* end of list */ }
      },
  };
  
  static inline uint32_t blk_log_writes_log2(uint32_t value)
  {
      assert(value > 0);
      return 31 - clz32(value);
  }
  
  static inline bool blk_log_writes_sector_size_valid(uint32_t sector_size)
  {
      return is_power_of_2(sector_size) &&
          sector_size >= sizeof(struct log_write_super) &&
          sector_size >= sizeof(struct log_write_entry) &&
          sector_size < (1ull << 24);
  }
  
  static uint64_t blk_log_writes_find_cur_log_sector(BdrvChild *log,
                                                     uint32_t sector_size,
                                                     uint64_t nr_entries,
                                                     Error **errp)
  {
      uint64_t cur_sector = 1;
      uint64_t cur_idx = 0;
      uint32_t sector_bits = blk_log_writes_log2(sector_size);
      struct log_write_entry cur_entry;
  
      while (cur_idx < nr_entries) {
          int read_ret = bdrv_pread(log, cur_sector << sector_bits, &cur_entry,
                                    sizeof(cur_entry));
          if (read_ret < 0) {
              error_setg_errno(errp, -read_ret,
                               "Failed to read log entry %"PRIu64, cur_idx);
              return (uint64_t)-1ull;
          }
  
          if (cur_entry.flags & ~cpu_to_le64(LOG_FLAG_MASK)) {
              error_setg(errp, "Invalid flags 0x%"PRIx64" in log entry %"PRIu64,
                         le64_to_cpu(cur_entry.flags), cur_idx);
              return (uint64_t)-1ull;
          }
  
          /* Account for the sector of the entry itself */
          ++cur_sector;
  
          /*
           * Account for the data of the write.
           * For discards, this data is not present.
           */
          if (!(cur_entry.flags & cpu_to_le64(LOG_DISCARD_FLAG))) {
              cur_sector += le64_to_cpu(cur_entry.nr_sectors);
          }
  
          ++cur_idx;
      }
  
      return cur_sector;
  }
  
  static int blk_log_writes_open(BlockDriverState *bs, QDict *options, int flags,
                                 Error **errp)
  {
      BDRVBlkLogWritesState *s = bs->opaque;
      QemuOpts *opts;
      Error *local_err = NULL;
      int ret;
      uint64_t log_sector_size;
      bool log_append;
  
      opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
      if (!qemu_opts_absorb_qdict(opts, options, errp)) {
          ret = -EINVAL;
          goto fail;
      }
  
      /* Open the file */
      bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
                                 BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY, false,
                                 errp);
      if (!bs->file) {
          ret = -EINVAL;
          goto fail;
      }
  
      /* Open the log file */
      s->log_file = bdrv_open_child(NULL, options, "log", bs, &child_of_bds,
                                    BDRV_CHILD_METADATA, false, errp);
      if (!s->log_file) {
          ret = -EINVAL;
          goto fail;
      }
  
      log_append = qemu_opt_get_bool(opts, "log-append", false);
  
      if (log_append) {
          struct log_write_super log_sb = { 0, 0, 0, 0 };
  
          if (qemu_opt_find(opts, "log-sector-size")) {
              ret = -EINVAL;
              error_setg(errp, "log-append and log-sector-size are mutually "
                         "exclusive");
              goto fail_log;
          }
  
          /* Read log superblock or fake one for an empty log */
          if (!bdrv_getlength(s->log_file->bs)) {
              log_sb.magic      = cpu_to_le64(WRITE_LOG_MAGIC);
              log_sb.version    = cpu_to_le64(WRITE_LOG_VERSION);
              log_sb.nr_entries = cpu_to_le64(0);
              log_sb.sectorsize = cpu_to_le32(BDRV_SECTOR_SIZE);
          } else {
              ret = bdrv_pread(s->log_file, 0, &log_sb, sizeof(log_sb));
              if (ret < 0) {
                  error_setg_errno(errp, -ret, "Could not read log superblock");
                  goto fail_log;
              }
          }
  
          if (log_sb.magic != cpu_to_le64(WRITE_LOG_MAGIC)) {
              ret = -EINVAL;
              error_setg(errp, "Invalid log superblock magic");
              goto fail_log;
          }
  
          if (log_sb.version != cpu_to_le64(WRITE_LOG_VERSION)) {
              ret = -EINVAL;
              error_setg(errp, "Unsupported log version %"PRIu64,
                         le64_to_cpu(log_sb.version));
              goto fail_log;
          }
  
          log_sector_size = le32_to_cpu(log_sb.sectorsize);
          s->cur_log_sector = 1;
          s->nr_entries = 0;
  
          if (blk_log_writes_sector_size_valid(log_sector_size)) {
              s->cur_log_sector =
                  blk_log_writes_find_cur_log_sector(s->log_file, log_sector_size,
                                      le64_to_cpu(log_sb.nr_entries), &local_err);
              if (local_err) {
                  ret = -EINVAL;
                  error_propagate(errp, local_err);
                  goto fail_log;
              }
  
              s->nr_entries = le64_to_cpu(log_sb.nr_entries);
          }
      } else {
          log_sector_size = qemu_opt_get_size(opts, "log-sector-size",
                                              BDRV_SECTOR_SIZE);
          s->cur_log_sector = 1;
          s->nr_entries = 0;
      }
  
      if (!blk_log_writes_sector_size_valid(log_sector_size)) {
          ret = -EINVAL;
          error_setg(errp, "Invalid log sector size %"PRIu64, log_sector_size);
          goto fail_log;
      }
  
      s->sectorsize = log_sector_size;
      s->sectorbits = blk_log_writes_log2(log_sector_size);
      s->update_interval = qemu_opt_get_number(opts, "log-super-update-interval",
                                               4096);
      if (!s->update_interval) {
          ret = -EINVAL;
          error_setg(errp, "Invalid log superblock update interval %"PRIu64,
                     s->update_interval);
          goto fail_log;
      }
  
      ret = 0;
  fail_log:
      if (ret < 0) {
          bdrv_unref_child(bs, s->log_file);
          s->log_file = NULL;
      }
  fail:
      if (ret < 0) {
          bdrv_unref_child(bs, bs->file);
          bs->file = NULL;
      }
      qemu_opts_del(opts);
      return ret;
  }
  
  static void blk_log_writes_close(BlockDriverState *bs)
  {
      BDRVBlkLogWritesState *s = bs->opaque;
  
      bdrv_unref_child(bs, s->log_file);
      s->log_file = NULL;
  }
  
  static int64_t blk_log_writes_getlength(BlockDriverState *bs)
  {
      return bdrv_getlength(bs->file->bs);
  }
  
  static void blk_log_writes_child_perm(BlockDriverState *bs, BdrvChild *c,
                                        BdrvChildRole role,
                                        BlockReopenQueue *ro_q,
                                        uint64_t perm, uint64_t shrd,
                                        uint64_t *nperm, uint64_t *nshrd)
  {
      if (!c) {
          *nperm = perm & DEFAULT_PERM_PASSTHROUGH;
          *nshrd = (shrd & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED;
          return;
      }
  
      bdrv_default_perms(bs, c, role, ro_q, perm, shrd,
                         nperm, nshrd);
  }
  
  static void blk_log_writes_refresh_limits(BlockDriverState *bs, Error **errp)
  {
      BDRVBlkLogWritesState *s = bs->opaque;
      bs->bl.request_alignment = s->sectorsize;
  }
  
  static int coroutine_fn
  blk_log_writes_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
                           QEMUIOVector *qiov, int flags)
  {
      return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
  }
  
  typedef struct BlkLogWritesFileReq {
      BlockDriverState *bs;
      uint64_t offset;
      uint64_t bytes;
      int file_flags;
      QEMUIOVector *qiov;
      int (*func)(struct BlkLogWritesFileReq *r);
      int file_ret;
  } BlkLogWritesFileReq;
  
  typedef struct {
      BlockDriverState *bs;
      QEMUIOVector *qiov;
      struct log_write_entry entry;
      uint64_t zero_size;
      int log_ret;
  } BlkLogWritesLogReq;
  
  static void coroutine_fn blk_log_writes_co_do_log(BlkLogWritesLogReq *lr)
  {
      BDRVBlkLogWritesState *s = lr->bs->opaque;
      uint64_t cur_log_offset = s->cur_log_sector << s->sectorbits;
  
      s->nr_entries++;
      s->cur_log_sector +=
              ROUND_UP(lr->qiov->size, s->sectorsize) >> s->sectorbits;
  
      lr->log_ret = bdrv_co_pwritev(s->log_file, cur_log_offset, lr->qiov->size,
                                    lr->qiov, 0);
  
      /* Logging for the "write zeroes" operation */
      if (lr->log_ret == 0 && lr->zero_size) {
          cur_log_offset = s->cur_log_sector << s->sectorbits;
          s->cur_log_sector +=
                  ROUND_UP(lr->zero_size, s->sectorsize) >> s->sectorbits;
  
          lr->log_ret = bdrv_co_pwrite_zeroes(s->log_file, cur_log_offset,
                                              lr->zero_size, 0);
      }
  
      /* Update super block on flush or every update interval */
      if (lr->log_ret == 0 && ((lr->entry.flags & LOG_FLUSH_FLAG)
          || (s->nr_entries % s->update_interval == 0)))
      {
          struct log_write_super super = {
              .magic      = cpu_to_le64(WRITE_LOG_MAGIC),
              .version    = cpu_to_le64(WRITE_LOG_VERSION),
              .nr_entries = cpu_to_le64(s->nr_entries),
              .sectorsize = cpu_to_le32(s->sectorsize),
          };
          void *zeroes = g_malloc0(s->sectorsize - sizeof(super));
          QEMUIOVector qiov;
  
          qemu_iovec_init(&qiov, 2);
          qemu_iovec_add(&qiov, &super, sizeof(super));
          qemu_iovec_add(&qiov, zeroes, s->sectorsize - sizeof(super));
  
          lr->log_ret =
              bdrv_co_pwritev(s->log_file, 0, s->sectorsize, &qiov, 0);
          if (lr->log_ret == 0) {
              lr->log_ret = bdrv_co_flush(s->log_file->bs);
          }
          qemu_iovec_destroy(&qiov);
          g_free(zeroes);
      }
  }
  
  static void coroutine_fn blk_log_writes_co_do_file(BlkLogWritesFileReq *fr)
  {
      fr->file_ret = fr->func(fr);
  }
  
  static int coroutine_fn
  blk_log_writes_co_log(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
                        QEMUIOVector *qiov, int flags,
                        int (*file_func)(BlkLogWritesFileReq *r),
                        uint64_t entry_flags, bool is_zero_write)
  {
      QEMUIOVector log_qiov;
      size_t niov = qiov ? qiov->niov : 0;
      BDRVBlkLogWritesState *s = bs->opaque;
      BlkLogWritesFileReq fr = {
          .bs         = bs,
          .offset     = offset,
          .bytes      = bytes,
          .file_flags = flags,
          .qiov       = qiov,
          .func       = file_func,
      };
      BlkLogWritesLogReq lr = {
          .bs             = bs,
          .qiov           = &log_qiov,
          .entry = {
              .sector     = cpu_to_le64(offset >> s->sectorbits),
              .nr_sectors = cpu_to_le64(bytes >> s->sectorbits),
              .flags      = cpu_to_le64(entry_flags),
              .data_len   = 0,
          },
          .zero_size = is_zero_write ? bytes : 0,
      };
      void *zeroes = g_malloc0(s->sectorsize - sizeof(lr.entry));
  
      assert((1 << s->sectorbits) == s->sectorsize);
      assert(bs->bl.request_alignment == s->sectorsize);
      assert(QEMU_IS_ALIGNED(offset, bs->bl.request_alignment));
      assert(QEMU_IS_ALIGNED(bytes, bs->bl.request_alignment));
  
      qemu_iovec_init(&log_qiov, niov + 2);
      qemu_iovec_add(&log_qiov, &lr.entry, sizeof(lr.entry));
      qemu_iovec_add(&log_qiov, zeroes, s->sectorsize - sizeof(lr.entry));
      if (qiov) {
          qemu_iovec_concat(&log_qiov, qiov, 0, qiov->size);
      }
  
      blk_log_writes_co_do_file(&fr);
      blk_log_writes_co_do_log(&lr);
  
      qemu_iovec_destroy(&log_qiov);
      g_free(zeroes);
  
      if (lr.log_ret < 0) {
          return lr.log_ret;
      }
  
      return fr.file_ret;
  }
  
  static int coroutine_fn
  blk_log_writes_co_do_file_pwritev(BlkLogWritesFileReq *fr)
  {
      return bdrv_co_pwritev(fr->bs->file, fr->offset, fr->bytes,
                             fr->qiov, fr->file_flags);
  }
  
  static int coroutine_fn
  blk_log_writes_co_do_file_pwrite_zeroes(BlkLogWritesFileReq *fr)
  {
      return bdrv_co_pwrite_zeroes(fr->bs->file, fr->offset, fr->bytes,
                                   fr->file_flags);
  }
  
  static int coroutine_fn blk_log_writes_co_do_file_flush(BlkLogWritesFileReq *fr)
  {
      return bdrv_co_flush(fr->bs->file->bs);
  }
  
  static int coroutine_fn
  blk_log_writes_co_do_file_pdiscard(BlkLogWritesFileReq *fr)
  {
      return bdrv_co_pdiscard(fr->bs->file, fr->offset, fr->bytes);
  }
  
  static int coroutine_fn
  blk_log_writes_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
                            QEMUIOVector *qiov, int flags)
  {
      return blk_log_writes_co_log(bs, offset, bytes, qiov, flags,
                                   blk_log_writes_co_do_file_pwritev, 0, false);
  }
  
  static int coroutine_fn
  blk_log_writes_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int bytes,
                                  BdrvRequestFlags flags)
  {
      return blk_log_writes_co_log(bs, offset, bytes, NULL, flags,
                                   blk_log_writes_co_do_file_pwrite_zeroes, 0,
                                   true);
  }
  
  static int coroutine_fn blk_log_writes_co_flush_to_disk(BlockDriverState *bs)
  {
      return blk_log_writes_co_log(bs, 0, 0, NULL, 0,
                                   blk_log_writes_co_do_file_flush,
                                   LOG_FLUSH_FLAG, false);
  }
  
  static int coroutine_fn
  blk_log_writes_co_pdiscard(BlockDriverState *bs, int64_t offset, int count)
  {
      return blk_log_writes_co_log(bs, offset, count, NULL, 0,
                                   blk_log_writes_co_do_file_pdiscard,
                                   LOG_DISCARD_FLAG, false);
  }
  
  static const char *const blk_log_writes_strong_runtime_opts[] = {
      "log-append",
      "log-sector-size",
  
      NULL
  };
  
  static BlockDriver bdrv_blk_log_writes = {
      .format_name            = "blklogwrites",
      .instance_size          = sizeof(BDRVBlkLogWritesState),
  
      .bdrv_open              = blk_log_writes_open,
      .bdrv_close             = blk_log_writes_close,
      .bdrv_getlength         = blk_log_writes_getlength,
      .bdrv_child_perm        = blk_log_writes_child_perm,
      .bdrv_refresh_limits    = blk_log_writes_refresh_limits,
  
      .bdrv_co_preadv         = blk_log_writes_co_preadv,
      .bdrv_co_pwritev        = blk_log_writes_co_pwritev,
      .bdrv_co_pwrite_zeroes  = blk_log_writes_co_pwrite_zeroes,
      .bdrv_co_flush_to_disk  = blk_log_writes_co_flush_to_disk,
      .bdrv_co_pdiscard       = blk_log_writes_co_pdiscard,
  
      .is_filter              = true,
      .strong_runtime_opts    = blk_log_writes_strong_runtime_opts,
  };
  
  static void bdrv_blk_log_writes_init(void)
  {
      bdrv_register(&bdrv_blk_log_writes);
  }
  
  block_init(bdrv_blk_log_writes_init);
  