text: /*
   * Block driver for Hyper-V VHDX Images
   *
   * Copyright (c) 2013 Red Hat, Inc.,
   *
   * Authors:
   *  Jeff Cody <jcody@redhat.com>
   *
   *  This is based on the "VHDX Format Specification v1.00", published 8/25/2012
   *  by Microsoft:
   *      https://www.microsoft.com/en-us/download/details.aspx?id=34750
   *
   * This work is licensed under the terms of the GNU LGPL, version 2 or later.
   * See the COPYING.LIB file in the top-level directory.
   *
   */
  
  #include "qemu/osdep.h"
  #include "qapi/error.h"
  #include "block/block_int.h"
  #include "block/qdict.h"
  #include "sysemu/block-backend.h"
  #include "qemu/module.h"
  #include "qemu/option.h"
  #include "qemu/crc32c.h"
  #include "qemu/bswap.h"
  #include "vhdx.h"
  #include "migration/blocker.h"
  #include "qemu/uuid.h"
  #include "qapi/qmp/qdict.h"
  #include "qapi/qobject-input-visitor.h"
  #include "qapi/qapi-visit-block-core.h"
  
  /* Options for VHDX creation */
  
  #define VHDX_BLOCK_OPT_LOG_SIZE   "log_size"
  #define VHDX_BLOCK_OPT_BLOCK_SIZE "block_size"
  #define VHDX_BLOCK_OPT_ZERO "block_state_zero"
  
  typedef enum VHDXImageType {
      VHDX_TYPE_DYNAMIC = 0,
      VHDX_TYPE_FIXED,
      VHDX_TYPE_DIFFERENCING,   /* Currently unsupported */
  } VHDXImageType;
  
  static QemuOptsList vhdx_create_opts;
  
  /* Several metadata and region table data entries are identified by
   * guids in  a MS-specific GUID format. */
  
  
  /* ------- Known Region Table GUIDs ---------------------- */
  static const MSGUID bat_guid =      { .data1 = 0x2dc27766,
                                        .data2 = 0xf623,
                                        .data3 = 0x4200,
                                        .data4 = { 0x9d, 0x64, 0x11, 0x5e,
                                                   0x9b, 0xfd, 0x4a, 0x08} };
  
  static const MSGUID metadata_guid = { .data1 = 0x8b7ca206,
                                        .data2 = 0x4790,
                                        .data3 = 0x4b9a,
                                        .data4 = { 0xb8, 0xfe, 0x57, 0x5f,
                                                   0x05, 0x0f, 0x88, 0x6e} };
  
  
  
  /* ------- Known Metadata Entry GUIDs ---------------------- */
  static const MSGUID file_param_guid =   { .data1 = 0xcaa16737,
                                            .data2 = 0xfa36,
                                            .data3 = 0x4d43,
                                            .data4 = { 0xb3, 0xb6, 0x33, 0xf0,
                                                       0xaa, 0x44, 0xe7, 0x6b} };
  
  static const MSGUID virtual_size_guid = { .data1 = 0x2FA54224,
                                            .data2 = 0xcd1b,
                                            .data3 = 0x4876,
                                            .data4 = { 0xb2, 0x11, 0x5d, 0xbe,
                                                       0xd8, 0x3b, 0xf4, 0xb8} };
  
  static const MSGUID page83_guid =       { .data1 = 0xbeca12ab,
                                            .data2 = 0xb2e6,
                                            .data3 = 0x4523,
                                            .data4 = { 0x93, 0xef, 0xc3, 0x09,
                                                       0xe0, 0x00, 0xc7, 0x46} };
  
  
  static const MSGUID phys_sector_guid =  { .data1 = 0xcda348c7,
                                            .data2 = 0x445d,
                                            .data3 = 0x4471,
                                            .data4 = { 0x9c, 0xc9, 0xe9, 0x88,
                                                       0x52, 0x51, 0xc5, 0x56} };
  
  static const MSGUID parent_locator_guid = { .data1 = 0xa8d35f2d,
                                              .data2 = 0xb30b,
                                              .data3 = 0x454d,
                                              .data4 = { 0xab, 0xf7, 0xd3,
                                                         0xd8, 0x48, 0x34,
                                                         0xab, 0x0c} };
  
  static const MSGUID logical_sector_guid = { .data1 = 0x8141bf1d,
                                              .data2 = 0xa96f,
                                              .data3 = 0x4709,
                                              .data4 = { 0xba, 0x47, 0xf2,
                                                         0x33, 0xa8, 0xfa,
                                                         0xab, 0x5f} };
  
  /* Each parent type must have a valid GUID; this is for parent images
   * of type 'VHDX'.  If we were to allow e.g. a QCOW2 parent, we would
   * need to make up our own QCOW2 GUID type */
  static const MSGUID parent_vhdx_guid __attribute__((unused))
                                       = { .data1 = 0xb04aefb7,
                                           .data2 = 0xd19e,
                                           .data3 = 0x4a81,
                                           .data4 = { 0xb7, 0x89, 0x25, 0xb8,
                                                      0xe9, 0x44, 0x59, 0x13} };
  
  
  #define META_FILE_PARAMETER_PRESENT      0x01
  #define META_VIRTUAL_DISK_SIZE_PRESENT   0x02
  #define META_PAGE_83_PRESENT             0x04
  #define META_LOGICAL_SECTOR_SIZE_PRESENT 0x08
  #define META_PHYS_SECTOR_SIZE_PRESENT    0x10
  #define META_PARENT_LOCATOR_PRESENT      0x20
  
  #define META_ALL_PRESENT    \
      (META_FILE_PARAMETER_PRESENT | META_VIRTUAL_DISK_SIZE_PRESENT | \
       META_PAGE_83_PRESENT | META_LOGICAL_SECTOR_SIZE_PRESENT | \
       META_PHYS_SECTOR_SIZE_PRESENT)
  
  
  typedef struct VHDXSectorInfo {
      uint32_t bat_idx;       /* BAT entry index */
      uint32_t sectors_avail; /* sectors available in payload block */
      uint32_t bytes_left;    /* bytes left in the block after data to r/w */
      uint32_t bytes_avail;   /* bytes available in payload block */
      uint64_t file_offset;   /* absolute offset in bytes, in file */
      uint64_t block_offset;  /* block offset, in bytes */
  } VHDXSectorInfo;
  
  /* Calculates new checksum.
   *
   * Zero is substituted during crc calculation for the original crc field
   * crc_offset: byte offset in buf of the buffer crc
   * buf: buffer pointer
   * size: size of buffer (must be > crc_offset+4)
   *
   * Note: The buffer should have all multi-byte data in little-endian format,
   *       and the resulting checksum is in little endian format.
   */
  uint32_t vhdx_update_checksum(uint8_t *buf, size_t size, int crc_offset)
  {
      uint32_t crc;
  
      assert(buf != NULL);
      assert(size > (crc_offset + sizeof(crc)));
  
      memset(buf + crc_offset, 0, sizeof(crc));
      crc =  crc32c(0xffffffff, buf, size);
      crc = cpu_to_le32(crc);
      memcpy(buf + crc_offset, &crc, sizeof(crc));
  
      return crc;
  }
  
  uint32_t vhdx_checksum_calc(uint32_t crc, uint8_t *buf, size_t size,
                              int crc_offset)
  {
      uint32_t crc_new;
      uint32_t crc_orig;
      assert(buf != NULL);
  
      if (crc_offset > 0) {
          memcpy(&crc_orig, buf + crc_offset, sizeof(crc_orig));
          memset(buf + crc_offset, 0, sizeof(crc_orig));
      }
  
      crc_new = crc32c(crc, buf, size);
      if (crc_offset > 0) {
          memcpy(buf + crc_offset, &crc_orig, sizeof(crc_orig));
      }
  
      return crc_new;
  }
  
  /* Validates the checksum of the buffer, with an in-place CRC.
   *
   * Zero is substituted during crc calculation for the original crc field,
   * and the crc field is restored afterwards.  But the buffer will be modified
   * during the calculation, so this may not be not suitable for multi-threaded
   * use.
   *
   * crc_offset: byte offset in buf of the buffer crc
   * buf: buffer pointer
   * size: size of buffer (must be > crc_offset+4)
   *
   * returns true if checksum is valid, false otherwise
   */
  bool vhdx_checksum_is_valid(uint8_t *buf, size_t size, int crc_offset)
  {
      uint32_t crc_orig;
      uint32_t crc;
  
      assert(buf != NULL);
      assert(size > (crc_offset + 4));
  
      memcpy(&crc_orig, buf + crc_offset, sizeof(crc_orig));
      crc_orig = le32_to_cpu(crc_orig);
  
      crc = vhdx_checksum_calc(0xffffffff, buf, size, crc_offset);
  
      return crc == crc_orig;
  }
  
  
  /*
   * This generates a UUID that is compliant with the MS GUIDs used
   * in the VHDX spec (and elsewhere).
   */
  void vhdx_guid_generate(MSGUID *guid)
  {
      QemuUUID uuid;
      assert(guid != NULL);
  
      qemu_uuid_generate(&uuid);
      memcpy(guid, &uuid, sizeof(MSGUID));
  }
  
  /* Check for region overlaps inside the VHDX image */
  static int vhdx_region_check(BDRVVHDXState *s, uint64_t start, uint64_t length)
  {
      int ret = 0;
      uint64_t end;
      VHDXRegionEntry *r;
  
      end = start + length;
      QLIST_FOREACH(r, &s->regions, entries) {
          if (!((start >= r->end) || (end <= r->start))) {
              ret = -EINVAL;
              goto exit;
          }
      }
  
  exit:
      return ret;
  }
  
  /* Register a region for future checks */
  static void vhdx_region_register(BDRVVHDXState *s,
                                   uint64_t start, uint64_t length)
  {
      VHDXRegionEntry *r;
  
      r = g_malloc0(sizeof(*r));
  
      r->start = start;
      r->end = start + length;
  
      QLIST_INSERT_HEAD(&s->regions, r, entries);
  }
  
  /* Free all registered regions */
  static void vhdx_region_unregister_all(BDRVVHDXState *s)
  {
      VHDXRegionEntry *r, *r_next;
  
      QLIST_FOREACH_SAFE(r, &s->regions, entries, r_next) {
          QLIST_REMOVE(r, entries);
          g_free(r);
      }
  }
  
  static void vhdx_set_shift_bits(BDRVVHDXState *s)
  {
      s->logical_sector_size_bits = ctz32(s->logical_sector_size);
      s->sectors_per_block_bits =   ctz32(s->sectors_per_block);
      s->chunk_ratio_bits =         ctz64(s->chunk_ratio);
      s->block_size_bits =          ctz32(s->block_size);
  }
  
  /*
   * Per the MS VHDX Specification, for every VHDX file:
   *      - The header section is fixed size - 1 MB
   *      - The header section is always the first "object"
   *      - The first 64KB of the header is the File Identifier
   *      - The first uint64 (8 bytes) is the VHDX Signature ("vhdxfile")
   *      - The following 512 bytes constitute a UTF-16 string identifiying the
   *        software that created the file, and is optional and diagnostic only.
   *
   *  Therefore, we probe by looking for the vhdxfile signature "vhdxfile"
   */
  static int vhdx_probe(const uint8_t *buf, int buf_size, const char *filename)
  {
      if (buf_size >= 8 && !memcmp(buf, "vhdxfile", 8)) {
          return 100;
      }
      return 0;
  }
  
  /*
   * Writes the header to the specified offset.
   *
   * This will optionally read in buffer data from disk (otherwise zero-fill),
   * and then update the header checksum.  Header is converted to proper
   * endianness before being written to the specified file offset
   */
  static int vhdx_write_header(BdrvChild *file, VHDXHeader *hdr,
                               uint64_t offset, bool read)
  {
      BlockDriverState *bs_file = file->bs;
      uint8_t *buffer = NULL;
      int ret;
      VHDXHeader *header_le;
  
      assert(bs_file != NULL);
      assert(hdr != NULL);
  
      /* the header checksum is not over just the packed size of VHDXHeader,
       * but rather over the entire 'reserved' range for the header, which is
       * 4KB (VHDX_HEADER_SIZE). */
  
      buffer = qemu_blockalign(bs_file, VHDX_HEADER_SIZE);
      if (read) {
          /* if true, we can't assume the extra reserved bytes are 0 */
          ret = bdrv_pread(file, offset, buffer, VHDX_HEADER_SIZE);
          if (ret < 0) {
              goto exit;
          }
      } else {
          memset(buffer, 0, VHDX_HEADER_SIZE);
      }
  
      /* overwrite the actual VHDXHeader portion */
      header_le = (VHDXHeader *)buffer;
      memcpy(header_le, hdr, sizeof(VHDXHeader));
      vhdx_header_le_export(hdr, header_le);
      vhdx_update_checksum(buffer, VHDX_HEADER_SIZE,
                           offsetof(VHDXHeader, checksum));
      ret = bdrv_pwrite_sync(file, offset, header_le, sizeof(VHDXHeader));
  
  exit:
      qemu_vfree(buffer);
      return ret;
  }
  
  /* Update the VHDX headers
   *
   * This follows the VHDX spec procedures for header updates.
   *
   *  - non-current header is updated with largest sequence number
   */
  static int vhdx_update_header(BlockDriverState *bs, BDRVVHDXState *s,
                                bool generate_data_write_guid, MSGUID *log_guid)
  {
      int ret = 0;
      int hdr_idx = 0;
      uint64_t header_offset = VHDX_HEADER1_OFFSET;
  
      VHDXHeader *active_header;
      VHDXHeader *inactive_header;
  
      /* operate on the non-current header */
      if (s->curr_header == 0) {
          hdr_idx = 1;
          header_offset = VHDX_HEADER2_OFFSET;
      }
  
      active_header   = s->headers[s->curr_header];
      inactive_header = s->headers[hdr_idx];
  
      inactive_header->sequence_number = active_header->sequence_number + 1;
  
      /* a new file guid must be generated before any file write, including
       * headers */
      inactive_header->file_write_guid = s->session_guid;
  
      /* a new data guid only needs to be generated before any guest-visible
       * writes (i.e. something observable via virtual disk read) */
      if (generate_data_write_guid) {
          vhdx_guid_generate(&inactive_header->data_write_guid);
      }
  
      /* update the log guid if present */
      if (log_guid) {
          inactive_header->log_guid = *log_guid;
      }
  
      ret = vhdx_write_header(bs->file, inactive_header, header_offset, true);
      if (ret < 0) {
          goto exit;
      }
      s->curr_header = hdr_idx;
  
  exit:
      return ret;
  }
  
  /*
   * The VHDX spec calls for header updates to be performed twice, so that both
   * the current and non-current header have valid info
   */
  int vhdx_update_headers(BlockDriverState *bs, BDRVVHDXState *s,
                          bool generate_data_write_guid, MSGUID *log_guid)
  {
      int ret;
  
      ret = vhdx_update_header(bs, s, generate_data_write_guid, log_guid);
      if (ret < 0) {
          return ret;
      }
      ret = vhdx_update_header(bs, s, generate_data_write_guid, log_guid);
      return ret;
  }
  
  /* opens the specified header block from the VHDX file header section */
  static void vhdx_parse_header(BlockDriverState *bs, BDRVVHDXState *s,
                                Error **errp)
  {
      int ret;
      VHDXHeader *header1;
      VHDXHeader *header2;
      bool h1_valid = false;
      bool h2_valid = false;
      uint64_t h1_seq = 0;
      uint64_t h2_seq = 0;
      uint8_t *buffer;
  
      /* header1 & header2 are freed in vhdx_close() */
      header1 = qemu_blockalign(bs, sizeof(VHDXHeader));
      header2 = qemu_blockalign(bs, sizeof(VHDXHeader));
  
      buffer = qemu_blockalign(bs, VHDX_HEADER_SIZE);
  
      s->headers[0] = header1;
      s->headers[1] = header2;
  
      /* We have to read the whole VHDX_HEADER_SIZE instead of
       * sizeof(VHDXHeader), because the checksum is over the whole
       * region */
      ret = bdrv_pread(bs->file, VHDX_HEADER1_OFFSET, buffer,
                       VHDX_HEADER_SIZE);
      if (ret < 0) {
          goto fail;
      }
      /* copy over just the relevant portion that we need */
      memcpy(header1, buffer, sizeof(VHDXHeader));
  
      if (vhdx_checksum_is_valid(buffer, VHDX_HEADER_SIZE, 4)) {
          vhdx_header_le_import(header1);
          if (header1->signature == VHDX_HEADER_SIGNATURE &&
              header1->version == 1) {
              h1_seq = header1->sequence_number;
              h1_valid = true;
          }
      }
  
      ret = bdrv_pread(bs->file, VHDX_HEADER2_OFFSET, buffer,
                       VHDX_HEADER_SIZE);
      if (ret < 0) {
          goto fail;
      }
      /* copy over just the relevant portion that we need */
      memcpy(header2, buffer, sizeof(VHDXHeader));
  
      if (vhdx_checksum_is_valid(buffer, VHDX_HEADER_SIZE, 4)) {
          vhdx_header_le_import(header2);
          if (header2->signature == VHDX_HEADER_SIGNATURE &&
              header2->version == 1) {
              h2_seq = header2->sequence_number;
              h2_valid = true;
          }
      }
  
      /* If there is only 1 valid header (or no valid headers), we
       * don't care what the sequence numbers are */
      if (h1_valid && !h2_valid) {
          s->curr_header = 0;
      } else if (!h1_valid && h2_valid) {
          s->curr_header = 1;
      } else if (!h1_valid && !h2_valid) {
          goto fail;
      } else {
          /* If both headers are valid, then we choose the active one by the
           * highest sequence number.  If the sequence numbers are equal, that is
           * invalid */
          if (h1_seq > h2_seq) {
              s->curr_header = 0;
          } else if (h2_seq > h1_seq) {
              s->curr_header = 1;
          } else {
              /* The Microsoft Disk2VHD tool will create 2 identical
               * headers, with identical sequence numbers.  If the headers are
               * identical, don't consider the file corrupt */
              if (!memcmp(header1, header2, sizeof(VHDXHeader))) {
                  s->curr_header = 0;
              } else {
                  goto fail;
              }
          }
      }
  
      vhdx_region_register(s, s->headers[s->curr_header]->log_offset,
                              s->headers[s->curr_header]->log_length);
      goto exit;
  
  fail:
      error_setg_errno(errp, -ret, "No valid VHDX header found");
      qemu_vfree(header1);
      qemu_vfree(header2);
      s->headers[0] = NULL;
      s->headers[1] = NULL;
  exit:
      qemu_vfree(buffer);
  }
  
  
  static int vhdx_open_region_tables(BlockDriverState *bs, BDRVVHDXState *s)
  {
      int ret = 0;
      uint8_t *buffer;
      int offset = 0;
      VHDXRegionTableEntry rt_entry;
      uint32_t i;
      bool bat_rt_found = false;
      bool metadata_rt_found = false;
  
      /* We have to read the whole 64KB block, because the crc32 is over the
       * whole block */
      buffer = qemu_blockalign(bs, VHDX_HEADER_BLOCK_SIZE);
  
      ret = bdrv_pread(bs->file, VHDX_REGION_TABLE_OFFSET, buffer,
                       VHDX_HEADER_BLOCK_SIZE);
      if (ret < 0) {
          goto fail;
      }
      memcpy(&s->rt, buffer, sizeof(s->rt));
      offset += sizeof(s->rt);
  
      if (!vhdx_checksum_is_valid(buffer, VHDX_HEADER_BLOCK_SIZE, 4)) {
          ret = -EINVAL;
          goto fail;
      }
  
      vhdx_region_header_le_import(&s->rt);
  
      if (s->rt.signature != VHDX_REGION_SIGNATURE) {
          ret = -EINVAL;
          goto fail;
      }
  
  
      /* Per spec, maximum region table entry count is 2047 */
      if (s->rt.entry_count > 2047) {
          ret = -EINVAL;
          goto fail;
      }
  
      for (i = 0; i < s->rt.entry_count; i++) {
          memcpy(&rt_entry, buffer + offset, sizeof(rt_entry));
          offset += sizeof(rt_entry);
  
          vhdx_region_entry_le_import(&rt_entry);
  
          /* check for region overlap between these entries, and any
           * other memory regions in the file */
          ret = vhdx_region_check(s, rt_entry.file_offset, rt_entry.length);
          if (ret < 0) {
              goto fail;
          }
  
          vhdx_region_register(s, rt_entry.file_offset, rt_entry.length);
  
          /* see if we recognize the entry */
          if (guid_eq(rt_entry.guid, bat_guid)) {
              /* must be unique; if we have already found it this is invalid */
              if (bat_rt_found) {
                  ret = -EINVAL;
                  goto fail;
              }
              bat_rt_found = true;
              s->bat_rt = rt_entry;
              continue;
          }
  
          if (guid_eq(rt_entry.guid, metadata_guid)) {
              /* must be unique; if we have already found it this is invalid */
              if (metadata_rt_found) {
                  ret = -EINVAL;
                  goto fail;
              }
              metadata_rt_found = true;
              s->metadata_rt = rt_entry;
              continue;
          }
  
          if (rt_entry.data_bits & VHDX_REGION_ENTRY_REQUIRED) {
              /* cannot read vhdx file - required region table entry that
               * we do not understand.  per spec, we must fail to open */
              ret = -ENOTSUP;
              goto fail;
          }
      }
  
      if (!bat_rt_found || !metadata_rt_found) {
          ret = -EINVAL;
          goto fail;
      }
  
      ret = 0;
  
  fail:
      qemu_vfree(buffer);
      return ret;
  }
  
  
  
  /* Metadata initial parser
   *
   * This loads all the metadata entry fields.  This may cause additional
   * fields to be processed (e.g. parent locator, etc..).
   *
   * There are 5 Metadata items that are always required:
   *      - File Parameters (block size, has a parent)
   *      - Virtual Disk Size (size, in bytes, of the virtual drive)
   *      - Page 83 Data (scsi page 83 guid)
   *      - Logical Sector Size (logical sector size in bytes, either 512 or
   *                             4096.  We only support 512 currently)
   *      - Physical Sector Size (512 or 4096)
   *
   * Also, if the File Parameters indicate this is a differencing file,
   * we must also look for the Parent Locator metadata item.
   */
  static int vhdx_parse_metadata(BlockDriverState *bs, BDRVVHDXState *s)
  {
      int ret = 0;
      uint8_t *buffer;
      int offset = 0;
      uint32_t i = 0;
      VHDXMetadataTableEntry md_entry;
  
      buffer = qemu_blockalign(bs, VHDX_METADATA_TABLE_MAX_SIZE);
  
      ret = bdrv_pread(bs->file, s->metadata_rt.file_offset, buffer,
                       VHDX_METADATA_TABLE_MAX_SIZE);
      if (ret < 0) {
          goto exit;
      }
      memcpy(&s->metadata_hdr, buffer, sizeof(s->metadata_hdr));
      offset += sizeof(s->metadata_hdr);
  
      vhdx_metadata_header_le_import(&s->metadata_hdr);
  
      if (s->metadata_hdr.signature != VHDX_METADATA_SIGNATURE) {
          ret = -EINVAL;
          goto exit;
      }
  
      s->metadata_entries.present = 0;
  
      if ((s->metadata_hdr.entry_count * sizeof(md_entry)) >
          (VHDX_METADATA_TABLE_MAX_SIZE - offset)) {
          ret = -EINVAL;
          goto exit;
      }
  
      for (i = 0; i < s->metadata_hdr.entry_count; i++) {
          memcpy(&md_entry, buffer + offset, sizeof(md_entry));
          offset += sizeof(md_entry);
  
          vhdx_metadata_entry_le_import(&md_entry);
  
          if (guid_eq(md_entry.item_id, file_param_guid)) {
              if (s->metadata_entries.present & META_FILE_PARAMETER_PRESENT) {
                  ret = -EINVAL;
                  goto exit;
              }
              s->metadata_entries.file_parameters_entry = md_entry;
              s->metadata_entries.present |= META_FILE_PARAMETER_PRESENT;
              continue;
          }
  
          if (guid_eq(md_entry.item_id, virtual_size_guid)) {
              if (s->metadata_entries.present & META_VIRTUAL_DISK_SIZE_PRESENT) {
                  ret = -EINVAL;
                  goto exit;
              }
              s->metadata_entries.virtual_disk_size_entry = md_entry;
              s->metadata_entries.present |= META_VIRTUAL_DISK_SIZE_PRESENT;
              continue;
          }
  
          if (guid_eq(md_entry.item_id, page83_guid)) {
              if (s->metadata_entries.present & META_PAGE_83_PRESENT) {
                  ret = -EINVAL;
                  goto exit;
              }
              s->metadata_entries.page83_data_entry = md_entry;
              s->metadata_entries.present |= META_PAGE_83_PRESENT;
              continue;
          }
  
          if (guid_eq(md_entry.item_id, logical_sector_guid)) {
              if (s->metadata_entries.present &
                  META_LOGICAL_SECTOR_SIZE_PRESENT) {
                  ret = -EINVAL;
                  goto exit;
              }
              s->metadata_entries.logical_sector_size_entry = md_entry;
              s->metadata_entries.present |= META_LOGICAL_SECTOR_SIZE_PRESENT;
              continue;
          }
  
          if (guid_eq(md_entry.item_id, phys_sector_guid)) {
              if (s->metadata_entries.present & META_PHYS_SECTOR_SIZE_PRESENT) {
                  ret = -EINVAL;
                  goto exit;
              }
              s->metadata_entries.phys_sector_size_entry = md_entry;
              s->metadata_entries.present |= META_PHYS_SECTOR_SIZE_PRESENT;
              continue;
          }
  
          if (guid_eq(md_entry.item_id, parent_locator_guid)) {
              if (s->metadata_entries.present & META_PARENT_LOCATOR_PRESENT) {
                  ret = -EINVAL;
                  goto exit;
              }
              s->metadata_entries.parent_locator_entry = md_entry;
              s->metadata_entries.present |= META_PARENT_LOCATOR_PRESENT;
              continue;
          }
  
          if (md_entry.data_bits & VHDX_META_FLAGS_IS_REQUIRED) {
              /* cannot read vhdx file - required region table entry that
               * we do not understand.  per spec, we must fail to open */
              ret = -ENOTSUP;
              goto exit;
          }
      }
  
      if (s->metadata_entries.present != META_ALL_PRESENT) {
          ret = -ENOTSUP;
          goto exit;
      }
  
      ret = bdrv_pread(bs->file,
                       s->metadata_entries.file_parameters_entry.offset
                                           + s->metadata_rt.file_offset,
                       &s->params,
                       sizeof(s->params));
  
      if (ret < 0) {
          goto exit;
      }
  
      s->params.block_size = le32_to_cpu(s->params.block_size);
      s->params.data_bits = le32_to_cpu(s->params.data_bits);
  
  
      /* We now have the file parameters, so we can tell if this is a
       * differencing file (i.e.. has_parent), is dynamic or fixed
       * sized (leave_blocks_allocated), and the block size */
  
      /* The parent locator required iff the file parameters has_parent set */
      if (s->params.data_bits & VHDX_PARAMS_HAS_PARENT) {
          if (s->metadata_entries.present & META_PARENT_LOCATOR_PRESENT) {
              /* TODO: parse  parent locator fields */
              ret = -ENOTSUP; /* temp, until differencing files are supported */
              goto exit;
          } else {
              /* if has_parent is set, but there is not parent locator present,
               * then that is an invalid combination */
              ret = -EINVAL;
              goto exit;
          }
      }
  
      /* determine virtual disk size, logical sector size,
       * and phys sector size */
  
      ret = bdrv_pread(bs->file,
                       s->metadata_entries.virtual_disk_size_entry.offset
                                             + s->metadata_rt.file_offset,
                       &s->virtual_disk_size,
                       sizeof(uint64_t));
      if (ret < 0) {
          goto exit;
      }
      ret = bdrv_pread(bs->file,
                       s->metadata_entries.logical_sector_size_entry.offset
                                               + s->metadata_rt.file_offset,
                       &s->logical_sector_size,
                       sizeof(uint32_t));
      if (ret < 0) {
          goto exit;
      }
      ret = bdrv_pread(bs->file,
                       s->metadata_entries.phys_sector_size_entry.offset
                                            + s->metadata_rt.file_offset,
                       &s->physical_sector_size,
                       sizeof(uint32_t));
      if (ret < 0) {
          goto exit;
      }
  
      s->virtual_disk_size = le64_to_cpu(s->virtual_disk_size);
      s->logical_sector_size = le32_to_cpu(s->logical_sector_size);
      s->physical_sector_size = le32_to_cpu(s->physical_sector_size);
  
      if (s->params.block_size < VHDX_BLOCK_SIZE_MIN ||
          s->params.block_size > VHDX_BLOCK_SIZE_MAX) {
          ret = -EINVAL;
          goto exit;
      }
  
      /* only 2 supported sector sizes */
      if (s->logical_sector_size != 512 && s->logical_sector_size != 4096) {
          ret = -EINVAL;
          goto exit;
      }
  
      /* Both block_size and sector_size are guaranteed powers of 2, below.
         Due to range checks above, s->sectors_per_block can never be < 256 */
      s->sectors_per_block = s->params.block_size / s->logical_sector_size;
      s->chunk_ratio = (VHDX_MAX_SECTORS_PER_BLOCK) *
                       (uint64_t)s->logical_sector_size /
                       (uint64_t)s->params.block_size;
  
      /* These values are ones we will want to use for division / multiplication
       * later on, and they are all guaranteed (per the spec) to be powers of 2,
       * so we can take advantage of that for shift operations during
       * reads/writes */
      if (s->logical_sector_size & (s->logical_sector_size - 1)) {
          ret = -EINVAL;
          goto exit;
      }
      if (s->sectors_per_block & (s->sectors_per_block - 1)) {
          ret = -EINVAL;
          goto exit;
      }
      if (s->chunk_ratio & (s->chunk_ratio - 1)) {
          ret = -EINVAL;
          goto exit;
      }
      s->block_size = s->params.block_size;
      if (s->block_size & (s->block_size - 1)) {
          ret = -EINVAL;
          goto exit;
      }
  
      vhdx_set_shift_bits(s);
  
      ret = 0;
  
  exit:
      qemu_vfree(buffer);
      return ret;
  }
  
  /*
   * Calculate the number of BAT entries, including sector
   * bitmap entries.
   */
  static void vhdx_calc_bat_entries(BDRVVHDXState *s)
  {
      uint32_t data_blocks_cnt, bitmap_blocks_cnt;
  
      data_blocks_cnt = DIV_ROUND_UP(s->virtual_disk_size, s->block_size);
      bitmap_blocks_cnt = DIV_ROUND_UP(data_blocks_cnt, s->chunk_ratio);
  
      if (s->parent_entries) {
          s->bat_entries = bitmap_blocks_cnt * (s->chunk_ratio + 1);
      } else {
          s->bat_entries = data_blocks_cnt +
                           ((data_blocks_cnt - 1) >> s->chunk_ratio_bits);
      }
  
  }
  
  static void vhdx_close(BlockDriverState *bs)
  {
      BDRVVHDXState *s = bs->opaque;
      qemu_vfree(s->headers[0]);
      s->headers[0] = NULL;
      qemu_vfree(s->headers[1]);
      s->headers[1] = NULL;
      qemu_vfree(s->bat);
      s->bat = NULL;
      qemu_vfree(s->parent_entries);
      s->parent_entries = NULL;
      migrate_del_blocker(s->migration_blocker);
      error_free(s->migration_blocker);
      qemu_vfree(s->log.hdr);
      s->log.hdr = NULL;
      vhdx_region_unregister_all(s);
  }
  
  static int vhdx_open(BlockDriverState *bs, QDict *options, int flags,
                       Error **errp)
  {
      BDRVVHDXState *s = bs->opaque;
      int ret = 0;
      uint32_t i;
      uint64_t signature;
      Error *local_err = NULL;
  
      bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
                                 false, errp);
      if (!bs->file) {
          return -EINVAL;
      }
  
      s->bat = NULL;
      s->first_visible_write = true;
  
      qemu_co_mutex_init(&s->lock);
      QLIST_INIT(&s->regions);
  
      /* validate the file signature */
      ret = bdrv_pread(bs->file, 0, &signature, sizeof(uint64_t));
      if (ret < 0) {
          goto fail;
      }
      if (memcmp(&signature, "vhdxfile", 8)) {
          ret = -EINVAL;
          goto fail;
      }
  
      /* This is used for any header updates, for the file_write_guid.
       * The spec dictates that a new value should be used for the first
       * header update */
      vhdx_guid_generate(&s->session_guid);
  
      vhdx_parse_header(bs, s, &local_err);
      if (local_err != NULL) {
          error_propagate(errp, local_err);
          ret = -EINVAL;
          goto fail;
      }
  
      ret = vhdx_parse_log(bs, s, &s->log_replayed_on_open, errp);
      if (ret < 0) {
          goto fail;
      }
  
      ret = vhdx_open_region_tables(bs, s);
      if (ret < 0) {
          goto fail;
      }
  
      ret = vhdx_parse_metadata(bs, s);
      if (ret < 0) {
          goto fail;
      }
  
      s->block_size = s->params.block_size;
  
      /* the VHDX spec dictates that virtual_disk_size is always a multiple of
       * logical_sector_size */
      bs->total_sectors = s->virtual_disk_size >> s->logical_sector_size_bits;
  
      vhdx_calc_bat_entries(s);
  
      s->bat_offset = s->bat_rt.file_offset;
  
      if (s->bat_entries > s->bat_rt.length / sizeof(VHDXBatEntry)) {
          /* BAT allocation is not large enough for all entries */
          ret = -EINVAL;
          goto fail;
      }
  
      /* s->bat is freed in vhdx_close() */
      s->bat = qemu_try_blockalign(bs->file->bs, s->bat_rt.length);
      if (s->bat == NULL) {
          ret = -ENOMEM;
          goto fail;
      }
  
      ret = bdrv_pread(bs->file, s->bat_offset, s->bat, s->bat_rt.length);
      if (ret < 0) {
          goto fail;
      }
  
      uint64_t payblocks = s->chunk_ratio;
      /* endian convert, and verify populated BAT field file offsets against
       * region table and log entries */
      for (i = 0; i < s->bat_entries; i++) {
          s->bat[i] = le64_to_cpu(s->bat[i]);
          if (payblocks--) {
              /* payload bat entries */
              if ((s->bat[i] & VHDX_BAT_STATE_BIT_MASK) ==
                      PAYLOAD_BLOCK_FULLY_PRESENT) {
                  ret = vhdx_region_check(s, s->bat[i] & VHDX_BAT_FILE_OFF_MASK,
                                          s->block_size);
                  if (ret < 0) {
                      goto fail;
                  }
              }
          } else {
              payblocks = s->chunk_ratio;
              /* Once differencing files are supported, verify sector bitmap
               * blocks here */
          }
      }
  
      /* Disable migration when VHDX images are used */
      error_setg(&s->migration_blocker, "The vhdx format used by node '%s' "
                 "does not support live migration",
                 bdrv_get_device_or_node_name(bs));
      ret = migrate_add_blocker(s->migration_blocker, &local_err);
      if (local_err) {
          error_propagate(errp, local_err);
          error_free(s->migration_blocker);
          goto fail;
      }
  
      /* TODO: differencing files */
  
      return 0;
  fail:
      vhdx_close(bs);
      return ret;
  }
  
  static int vhdx_reopen_prepare(BDRVReopenState *state,
                                 BlockReopenQueue *queue, Error **errp)
  {
      return 0;
  }
  
  
  /*
   * Perform sector to block offset translations, to get various
   * sector and file offsets into the image.  See VHDXSectorInfo
   */
  static void vhdx_block_translate(BDRVVHDXState *s, int64_t sector_num,
                                   int nb_sectors, VHDXSectorInfo *sinfo)
  {
      uint32_t block_offset;
  
      sinfo->bat_idx = sector_num >> s->sectors_per_block_bits;
      /* effectively a modulo - this gives us the offset into the block
       * (in sector sizes) for our sector number */
      block_offset = sector_num - (sinfo->bat_idx << s->sectors_per_block_bits);
      /* the chunk ratio gives us the interleaving of the sector
       * bitmaps, so we need to advance our page block index by the
       * sector bitmaps entry number */
      sinfo->bat_idx += sinfo->bat_idx >> s->chunk_ratio_bits;
  
      /* the number of sectors we can read/write in this cycle */
      sinfo->sectors_avail = s->sectors_per_block - block_offset;
  
      sinfo->bytes_left = sinfo->sectors_avail << s->logical_sector_size_bits;
  
      if (sinfo->sectors_avail > nb_sectors) {
          sinfo->sectors_avail = nb_sectors;
      }
  
      sinfo->bytes_avail = sinfo->sectors_avail << s->logical_sector_size_bits;
  
      sinfo->file_offset = s->bat[sinfo->bat_idx] & VHDX_BAT_FILE_OFF_MASK;
  
      sinfo->block_offset = block_offset << s->logical_sector_size_bits;
  
      /* The file offset must be past the header section, so must be > 0 */
      if (sinfo->file_offset == 0) {
          return;
      }
  
      /* block offset is the offset in vhdx logical sectors, in
       * the payload data block. Convert that to a byte offset
       * in the block, and add in the payload data block offset
       * in the file, in bytes, to get the final read address */
  
      sinfo->file_offset += sinfo->block_offset;
  }
  
  
  static int vhdx_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
  {
      BDRVVHDXState *s = bs->opaque;
  
      bdi->cluster_size = s->block_size;
  
      bdi->unallocated_blocks_are_zero =
          (s->params.data_bits & VHDX_PARAMS_HAS_PARENT) == 0;
  
      return 0;
  }
  
  
  static coroutine_fn int vhdx_co_readv(BlockDriverState *bs, int64_t sector_num,
                                        int nb_sectors, QEMUIOVector *qiov)
  {
      BDRVVHDXState *s = bs->opaque;
      int ret = 0;
      VHDXSectorInfo sinfo;
      uint64_t bytes_done = 0;
      QEMUIOVector hd_qiov;
  
      qemu_iovec_init(&hd_qiov, qiov->niov);
  
      qemu_co_mutex_lock(&s->lock);
  
      while (nb_sectors > 0) {
          /* We are a differencing file, so we need to inspect the sector bitmap
           * to see if we have the data or not */
          if (s->params.data_bits & VHDX_PARAMS_HAS_PARENT) {
              /* not supported yet */
              ret = -ENOTSUP;
              goto exit;
          } else {
              vhdx_block_translate(s, sector_num, nb_sectors, &sinfo);
  
              qemu_iovec_reset(&hd_qiov);
              qemu_iovec_concat(&hd_qiov, qiov,  bytes_done, sinfo.bytes_avail);
  
              /* check the payload block state */
              switch (s->bat[sinfo.bat_idx] & VHDX_BAT_STATE_BIT_MASK) {
              case PAYLOAD_BLOCK_NOT_PRESENT: /* fall through */
              case PAYLOAD_BLOCK_UNDEFINED:
              case PAYLOAD_BLOCK_UNMAPPED:
              case PAYLOAD_BLOCK_UNMAPPED_v095:
              case PAYLOAD_BLOCK_ZERO:
                  /* return zero */
                  qemu_iovec_memset(&hd_qiov, 0, 0, sinfo.bytes_avail);
                  break;
              case PAYLOAD_BLOCK_FULLY_PRESENT:
                  qemu_co_mutex_unlock(&s->lock);
                  ret = bdrv_co_preadv(bs->file, sinfo.file_offset,
                                       sinfo.sectors_avail * BDRV_SECTOR_SIZE,
                                       &hd_qiov, 0);
                  qemu_co_mutex_lock(&s->lock);
                  if (ret < 0) {
                      goto exit;
                  }
                  break;
              case PAYLOAD_BLOCK_PARTIALLY_PRESENT:
                  /* we don't yet support difference files, fall through
                   * to error */
              default:
                  ret = -EIO;
                  goto exit;
                  break;
              }
              nb_sectors -= sinfo.sectors_avail;
              sector_num += sinfo.sectors_avail;
              bytes_done += sinfo.bytes_avail;
          }
      }
      ret = 0;
  exit:
      qemu_co_mutex_unlock(&s->lock);
      qemu_iovec_destroy(&hd_qiov);
      return ret;
  }
  
  /*
   * Allocate a new payload block at the end of the file.
   *
   * Allocation will happen at 1MB alignment inside the file
   *
   * Returns the file offset start of the new payload block
   */
  static int vhdx_allocate_block(BlockDriverState *bs, BDRVVHDXState *s,
                                      uint64_t *new_offset)
  {
      int64_t current_len;
  
      current_len = bdrv_getlength(bs->file->bs);
      if (current_len < 0) {
          return current_len;
      }
  
      *new_offset = current_len;
  
      /* per the spec, the address for a block is in units of 1MB */
      *new_offset = ROUND_UP(*new_offset, 1024 * 1024);
      if (*new_offset > INT64_MAX) {
          return -EINVAL;
      }
  
      return bdrv_truncate(bs->file, *new_offset + s->block_size,
                           PREALLOC_MODE_OFF, NULL);
  }
  
  /*
   * Update the BAT table entry with the new file offset, and the new entry
   * state */
  static void vhdx_update_bat_table_entry(BlockDriverState *bs, BDRVVHDXState *s,
                                         VHDXSectorInfo *sinfo,
                                         uint64_t *bat_entry_le,
                                         uint64_t *bat_offset, int state)
  {
      /* The BAT entry is a uint64, with 44 bits for the file offset in units of
       * 1MB, and 3 bits for the block state. */
      if ((state == PAYLOAD_BLOCK_ZERO)        ||
          (state == PAYLOAD_BLOCK_UNDEFINED)   ||
          (state == PAYLOAD_BLOCK_NOT_PRESENT) ||
          (state == PAYLOAD_BLOCK_UNMAPPED)) {
          s->bat[sinfo->bat_idx]  = 0;  /* For PAYLOAD_BLOCK_ZERO, the
                                           FileOffsetMB field is denoted as
                                           'reserved' in the v1.0 spec.  If it is
                                           non-zero, MS Hyper-V will fail to read
                                           the disk image */
      } else {
          s->bat[sinfo->bat_idx]  = sinfo->file_offset;
      }
  
      s->bat[sinfo->bat_idx] |= state & VHDX_BAT_STATE_BIT_MASK;
  
      *bat_entry_le = cpu_to_le64(s->bat[sinfo->bat_idx]);
      *bat_offset = s->bat_offset + sinfo->bat_idx * sizeof(VHDXBatEntry);
  
  }
  
  /* Per the spec, on the first write of guest-visible data to the file the
   * data write guid must be updated in the header */
  int vhdx_user_visible_write(BlockDriverState *bs, BDRVVHDXState *s)
  {
      int ret = 0;
      if (s->first_visible_write) {
          s->first_visible_write = false;
          ret = vhdx_update_headers(bs, s, true, NULL);
      }
      return ret;
  }
  
  static coroutine_fn int vhdx_co_writev(BlockDriverState *bs, int64_t sector_num,
                                         int nb_sectors, QEMUIOVector *qiov,
                                         int flags)
  {
      int ret = -ENOTSUP;
      BDRVVHDXState *s = bs->opaque;
      VHDXSectorInfo sinfo;
      uint64_t bytes_done = 0;
      uint64_t bat_entry = 0;
      uint64_t bat_entry_offset = 0;
      QEMUIOVector hd_qiov;
      struct iovec iov1 = { 0 };
      struct iovec iov2 = { 0 };
      int sectors_to_write;
      int bat_state;
      uint64_t bat_prior_offset = 0;
      bool bat_update = false;
  
      assert(!flags);
      qemu_iovec_init(&hd_qiov, qiov->niov);
  
      qemu_co_mutex_lock(&s->lock);
  
      ret = vhdx_user_visible_write(bs, s);
      if (ret < 0) {
          goto exit;
      }
  
      while (nb_sectors > 0) {
          bool use_zero_buffers = false;
          bat_update = false;
          if (s->params.data_bits & VHDX_PARAMS_HAS_PARENT) {
              /* not supported yet */
              ret = -ENOTSUP;
              goto exit;
          } else {
              vhdx_block_translate(s, sector_num, nb_sectors, &sinfo);
              sectors_to_write = sinfo.sectors_avail;
  
              qemu_iovec_reset(&hd_qiov);
              /* check the payload block state */
              bat_state = s->bat[sinfo.bat_idx] & VHDX_BAT_STATE_BIT_MASK;
              switch (bat_state) {
              case PAYLOAD_BLOCK_ZERO:
                  /* in this case, we need to preserve zero writes for
                   * data that is not part of this write, so we must pad
                   * the rest of the buffer to zeroes */
  
                  /* if we are on a posix system with ftruncate() that extends
                   * a file, then it is zero-filled for us.  On Win32, the raw
                   * layer uses SetFilePointer and SetFileEnd, which does not
                   * zero fill AFAIK */
  
                  /* Queue another write of zero buffers if the underlying file
                   * does not zero-fill on file extension */
  
                  if (bdrv_has_zero_init(bs->file->bs) == 0) {
                      use_zero_buffers = true;
  
                      /* zero fill the front, if any */
                      if (sinfo.block_offset) {
                          iov1.iov_len = sinfo.block_offset;
                          iov1.iov_base = qemu_blockalign(bs, iov1.iov_len);
                          memset(iov1.iov_base, 0, iov1.iov_len);
                          qemu_iovec_concat_iov(&hd_qiov, &iov1, 1, 0,
                                                iov1.iov_len);
                          sectors_to_write += iov1.iov_len >> BDRV_SECTOR_BITS;
                      }
  
                      /* our actual data */
                      qemu_iovec_concat(&hd_qiov, qiov,  bytes_done,
                                        sinfo.bytes_avail);
  
                      /* zero fill the back, if any */
                      if ((sinfo.bytes_avail - sinfo.block_offset) <
                           s->block_size) {
                          iov2.iov_len = s->block_size -
                                        (sinfo.bytes_avail + sinfo.block_offset);
                          iov2.iov_base = qemu_blockalign(bs, iov2.iov_len);
                          memset(iov2.iov_base, 0, iov2.iov_len);
                          qemu_iovec_concat_iov(&hd_qiov, &iov2, 1, 0,
                                                iov2.iov_len);
                          sectors_to_write += iov2.iov_len >> BDRV_SECTOR_BITS;
                      }
                  }
                  /* fall through */
              case PAYLOAD_BLOCK_NOT_PRESENT: /* fall through */
              case PAYLOAD_BLOCK_UNMAPPED:
              case PAYLOAD_BLOCK_UNMAPPED_v095:
              case PAYLOAD_BLOCK_UNDEFINED:
                  bat_prior_offset = sinfo.file_offset;
                  ret = vhdx_allocate_block(bs, s, &sinfo.file_offset);
                  if (ret < 0) {
                      goto exit;
                  }
                  /* once we support differencing files, this may also be
                   * partially present */
                  /* update block state to the newly specified state */
                  vhdx_update_bat_table_entry(bs, s, &sinfo, &bat_entry,
                                              &bat_entry_offset,
                                              PAYLOAD_BLOCK_FULLY_PRESENT);
                  bat_update = true;
                  /* since we just allocated a block, file_offset is the
                   * beginning of the payload block. It needs to be the
                   * write address, which includes the offset into the block */
                  if (!use_zero_buffers) {
                      sinfo.file_offset += sinfo.block_offset;
                  }
                  /* fall through */
              case PAYLOAD_BLOCK_FULLY_PRESENT:
                  /* if the file offset address is in the header zone,
                   * there is a problem */
                  if (sinfo.file_offset < (1024 * 1024)) {
                      ret = -EFAULT;
                      goto error_bat_restore;
                  }
  
                  if (!use_zero_buffers) {
                      qemu_iovec_concat(&hd_qiov, qiov,  bytes_done,
                                        sinfo.bytes_avail);
                  }
                  /* block exists, so we can just overwrite it */
                  qemu_co_mutex_unlock(&s->lock);
                  ret = bdrv_co_pwritev(bs->file, sinfo.file_offset,
                                        sectors_to_write * BDRV_SECTOR_SIZE,
                                        &hd_qiov, 0);
                  qemu_co_mutex_lock(&s->lock);
                  if (ret < 0) {
                      goto error_bat_restore;
                  }
                  break;
              case PAYLOAD_BLOCK_PARTIALLY_PRESENT:
                  /* we don't yet support difference files, fall through
                   * to error */
              default:
                  ret = -EIO;
                  goto exit;
                  break;
              }
  
              if (bat_update) {
                  /* this will update the BAT entry into the log journal, and
                   * then flush the log journal out to disk */
                  ret =  vhdx_log_write_and_flush(bs, s, &bat_entry,
                                                  sizeof(VHDXBatEntry),
                                                  bat_entry_offset);
                  if (ret < 0) {
                      goto exit;
                  }
              }
  
              nb_sectors -= sinfo.sectors_avail;
              sector_num += sinfo.sectors_avail;
              bytes_done += sinfo.bytes_avail;
  
          }
      }
  
      goto exit;
  
  error_bat_restore:
      if (bat_update) {
          /* keep metadata in sync, and restore the bat entry state
           * if error. */
          sinfo.file_offset = bat_prior_offset;
          vhdx_update_bat_table_entry(bs, s, &sinfo, &bat_entry,
                                      &bat_entry_offset, bat_state);
      }
  exit:
      qemu_vfree(iov1.iov_base);
      qemu_vfree(iov2.iov_base);
      qemu_co_mutex_unlock(&s->lock);
      qemu_iovec_destroy(&hd_qiov);
      return ret;
  }
  
  
  
  /*
   * Create VHDX Headers
   *
   * There are 2 headers, and the highest sequence number will represent
   * the active header
   */
  static int vhdx_create_new_headers(BlockBackend *blk, uint64_t image_size,
                                     uint32_t log_size)
  {
      BlockDriverState *bs = blk_bs(blk);
      BdrvChild *child;
      int ret = 0;
      VHDXHeader *hdr = NULL;
  
      hdr = g_new0(VHDXHeader, 1);
  
      hdr->signature       = VHDX_HEADER_SIGNATURE;
      hdr->sequence_number = g_random_int();
      hdr->log_version     = 0;
      hdr->version         = 1;
      hdr->log_length      = log_size;
      hdr->log_offset      = VHDX_HEADER_SECTION_END;
      vhdx_guid_generate(&hdr->file_write_guid);
      vhdx_guid_generate(&hdr->data_write_guid);
  
      /* XXX Ugly way to get blk->root, but that's a feature, not a bug. This
       * hack makes it obvious that vhdx_write_header() bypasses the BlockBackend
       * here, which it really shouldn't be doing. */
      child = QLIST_FIRST(&bs->parents);
      assert(!QLIST_NEXT(child, next_parent));
  
      ret = vhdx_write_header(child, hdr, VHDX_HEADER1_OFFSET, false);
      if (ret < 0) {
          goto exit;
      }
      hdr->sequence_number++;
      ret = vhdx_write_header(child, hdr, VHDX_HEADER2_OFFSET, false);
      if (ret < 0) {
          goto exit;
      }
  
  exit:
      g_free(hdr);
      return ret;
  }
  
  #define VHDX_METADATA_ENTRY_BUFFER_SIZE \
                                      (sizeof(VHDXFileParameters)               +\
                                       sizeof(VHDXVirtualDiskSize)              +\
                                       sizeof(VHDXPage83Data)                   +\
                                       sizeof(VHDXVirtualDiskLogicalSectorSize) +\
                                       sizeof(VHDXVirtualDiskPhysicalSectorSize))
  
  /*
   * Create the Metadata entries.
   *
   * For more details on the entries, see section 3.5 (pg 29) in the
   * VHDX 1.00 specification.
   *
   * We support 5 metadata entries (all required by spec):
   *          File Parameters,
   *          Virtual Disk Size,
   *          Page 83 Data,
   *          Logical Sector Size,
   *          Physical Sector Size
   *
   * The first 64KB of the Metadata section is reserved for the metadata
   * header and entries; beyond that, the metadata items themselves reside.
   */
  static int vhdx_create_new_metadata(BlockBackend *blk,
                                      uint64_t image_size,
                                      uint32_t block_size,
                                      uint32_t sector_size,
                                      uint64_t metadata_offset,
                                      VHDXImageType type)
  {
      int ret = 0;
      uint32_t offset = 0;
      void *buffer = NULL;
      void *entry_buffer;
      VHDXMetadataTableHeader *md_table;
      VHDXMetadataTableEntry  *md_table_entry;
  
      /* Metadata entries */
      VHDXFileParameters     *mt_file_params;
      VHDXVirtualDiskSize    *mt_virtual_size;
      VHDXPage83Data         *mt_page83;
      VHDXVirtualDiskLogicalSectorSize  *mt_log_sector_size;
      VHDXVirtualDiskPhysicalSectorSize *mt_phys_sector_size;
  
      entry_buffer = g_malloc0(VHDX_METADATA_ENTRY_BUFFER_SIZE);
  
      mt_file_params = entry_buffer;
      offset += sizeof(VHDXFileParameters);
      mt_virtual_size = entry_buffer + offset;
      offset += sizeof(VHDXVirtualDiskSize);
      mt_page83 = entry_buffer + offset;
      offset += sizeof(VHDXPage83Data);
      mt_log_sector_size = entry_buffer + offset;
      offset += sizeof(VHDXVirtualDiskLogicalSectorSize);
      mt_phys_sector_size = entry_buffer + offset;
  
      mt_file_params->block_size = cpu_to_le32(block_size);
      if (type == VHDX_TYPE_FIXED) {
          mt_file_params->data_bits |= VHDX_PARAMS_LEAVE_BLOCKS_ALLOCED;
          mt_file_params->data_bits = cpu_to_le32(mt_file_params->data_bits);
      }
  
      vhdx_guid_generate(&mt_page83->page_83_data);
      cpu_to_leguids(&mt_page83->page_83_data);
      mt_virtual_size->virtual_disk_size        = cpu_to_le64(image_size);
      mt_log_sector_size->logical_sector_size   = cpu_to_le32(sector_size);
      mt_phys_sector_size->physical_sector_size = cpu_to_le32(sector_size);
  
      buffer = g_malloc0(VHDX_HEADER_BLOCK_SIZE);
      md_table = buffer;
  
      md_table->signature   = VHDX_METADATA_SIGNATURE;
      md_table->entry_count = 5;
      vhdx_metadata_header_le_export(md_table);
  
  
      /* This will reference beyond the reserved table portion */
      offset = 64 * KiB;
  
      md_table_entry = buffer + sizeof(VHDXMetadataTableHeader);
  
      md_table_entry[0].item_id = file_param_guid;
      md_table_entry[0].offset  = offset;
      md_table_entry[0].length  = sizeof(VHDXFileParameters);
      md_table_entry[0].data_bits |= VHDX_META_FLAGS_IS_REQUIRED;
      offset += md_table_entry[0].length;
      vhdx_metadata_entry_le_export(&md_table_entry[0]);
  
      md_table_entry[1].item_id = virtual_size_guid;
      md_table_entry[1].offset  = offset;
      md_table_entry[1].length  = sizeof(VHDXVirtualDiskSize);
      md_table_entry[1].data_bits |= VHDX_META_FLAGS_IS_REQUIRED |
                                     VHDX_META_FLAGS_IS_VIRTUAL_DISK;
      offset += md_table_entry[1].length;
      vhdx_metadata_entry_le_export(&md_table_entry[1]);
  
      md_table_entry[2].item_id = page83_guid;
      md_table_entry[2].offset  = offset;
      md_table_entry[2].length  = sizeof(VHDXPage83Data);
      md_table_entry[2].data_bits |= VHDX_META_FLAGS_IS_REQUIRED |
                                     VHDX_META_FLAGS_IS_VIRTUAL_DISK;
      offset += md_table_entry[2].length;
      vhdx_metadata_entry_le_export(&md_table_entry[2]);
  
      md_table_entry[3].item_id = logical_sector_guid;
      md_table_entry[3].offset  = offset;
      md_table_entry[3].length  = sizeof(VHDXVirtualDiskLogicalSectorSize);
      md_table_entry[3].data_bits |= VHDX_META_FLAGS_IS_REQUIRED |
                                     VHDX_META_FLAGS_IS_VIRTUAL_DISK;
      offset += md_table_entry[3].length;
      vhdx_metadata_entry_le_export(&md_table_entry[3]);
  
      md_table_entry[4].item_id = phys_sector_guid;
      md_table_entry[4].offset  = offset;
      md_table_entry[4].length  = sizeof(VHDXVirtualDiskPhysicalSectorSize);
      md_table_entry[4].data_bits |= VHDX_META_FLAGS_IS_REQUIRED |
                                     VHDX_META_FLAGS_IS_VIRTUAL_DISK;
      vhdx_metadata_entry_le_export(&md_table_entry[4]);
  
      ret = blk_pwrite(blk, metadata_offset, buffer, VHDX_HEADER_BLOCK_SIZE, 0);
      if (ret < 0) {
          goto exit;
      }
  
      ret = blk_pwrite(blk, metadata_offset + (64 * KiB), entry_buffer,
                       VHDX_METADATA_ENTRY_BUFFER_SIZE, 0);
      if (ret < 0) {
          goto exit;
      }
  
  
  exit:
      g_free(buffer);
      g_free(entry_buffer);
      return ret;
  }
  
  /* This create the actual BAT itself.  We currently only support
   * 'Dynamic' and 'Fixed' image types.
   *
   *  Dynamic images: default state of the BAT is all zeroes.
   *
   *  Fixed images: default state of the BAT is fully populated, with
   *                file offsets and state PAYLOAD_BLOCK_FULLY_PRESENT.
   */
  static int vhdx_create_bat(BlockBackend *blk, BDRVVHDXState *s,
                             uint64_t image_size, VHDXImageType type,
                             bool use_zero_blocks, uint64_t file_offset,
                             uint32_t length, Error **errp)
  {
      int ret = 0;
      uint64_t data_file_offset;
      uint64_t total_sectors = 0;
      uint64_t sector_num = 0;
      uint64_t unused;
      int block_state;
      VHDXSectorInfo sinfo;
  
      assert(s->bat == NULL);
  
      /* this gives a data start after BAT/bitmap entries, and well
       * past any metadata entries (with a 4 MB buffer for future
       * expansion */
      data_file_offset = file_offset + length + 5 * MiB;
      total_sectors = image_size >> s->logical_sector_size_bits;
  
      if (type == VHDX_TYPE_DYNAMIC) {
          /* All zeroes, so we can just extend the file - the end of the BAT
           * is the furthest thing we have written yet */
          ret = blk_truncate(blk, data_file_offset, PREALLOC_MODE_OFF, errp);
          if (ret < 0) {
              goto exit;
          }
      } else if (type == VHDX_TYPE_FIXED) {
          ret = blk_truncate(blk, data_file_offset + image_size,
                             PREALLOC_MODE_OFF, errp);
          if (ret < 0) {
              goto exit;
          }
      } else {
          error_setg(errp, "Unsupported image type");
          ret = -ENOTSUP;
          goto exit;
      }
  
      if (type == VHDX_TYPE_FIXED ||
                  use_zero_blocks ||
                  bdrv_has_zero_init(blk_bs(blk)) == 0) {
          /* for a fixed file, the default BAT entry is not zero */
          s->bat = g_try_malloc0(length);
          if (length && s->bat == NULL) {
              error_setg(errp, "Failed to allocate memory for the BAT");
              ret = -ENOMEM;
              goto exit;
          }
          block_state = type == VHDX_TYPE_FIXED ? PAYLOAD_BLOCK_FULLY_PRESENT :
                                                  PAYLOAD_BLOCK_NOT_PRESENT;
          block_state = use_zero_blocks ? PAYLOAD_BLOCK_ZERO : block_state;
          /* fill the BAT by emulating sector writes of sectors_per_block size */
          while (sector_num < total_sectors) {
              vhdx_block_translate(s, sector_num, s->sectors_per_block, &sinfo);
              sinfo.file_offset = data_file_offset +
                                  (sector_num << s->logical_sector_size_bits);
              sinfo.file_offset = ROUND_UP(sinfo.file_offset, MiB);
              vhdx_update_bat_table_entry(blk_bs(blk), s, &sinfo, &unused, &unused,
                                          block_state);
              s->bat[sinfo.bat_idx] = cpu_to_le64(s->bat[sinfo.bat_idx]);
              sector_num += s->sectors_per_block;
          }
          ret = blk_pwrite(blk, file_offset, s->bat, length, 0);
          if (ret < 0) {
              error_setg_errno(errp, -ret, "Failed to write the BAT");
              goto exit;
          }
      }
  
  
  
  exit:
      g_free(s->bat);
      return ret;
  }
  
  /* Creates the region table header, and region table entries.
   * There are 2 supported region table entries: BAT, and Metadata/
   *
   * As the calculations for the BAT region table are also needed
   * to create the BAT itself, we will also cause the BAT to be
   * created.
   */
  static int vhdx_create_new_region_table(BlockBackend *blk,
                                          uint64_t image_size,
                                          uint32_t block_size,
                                          uint32_t sector_size,
                                          uint32_t log_size,
                                          bool use_zero_blocks,
                                          VHDXImageType type,
                                          uint64_t *metadata_offset,
                                          Error **errp)
  {
      int ret = 0;
      uint32_t offset = 0;
      void *buffer = NULL;
      uint64_t bat_file_offset;
      uint32_t bat_length;
      BDRVVHDXState *s = NULL;
      VHDXRegionTableHeader *region_table;
      VHDXRegionTableEntry *rt_bat;
      VHDXRegionTableEntry *rt_metadata;
  
      assert(metadata_offset != NULL);
  
      /* Populate enough of the BDRVVHDXState to be able to use the
       * pre-existing BAT calculation, translation, and update functions */
      s = g_new0(BDRVVHDXState, 1);
  
      s->chunk_ratio = (VHDX_MAX_SECTORS_PER_BLOCK) *
                       (uint64_t) sector_size / (uint64_t) block_size;
  
      s->sectors_per_block = block_size / sector_size;
      s->virtual_disk_size = image_size;
      s->block_size = block_size;
      s->logical_sector_size = sector_size;
  
      vhdx_set_shift_bits(s);
  
      vhdx_calc_bat_entries(s);
  
      /* At this point the VHDX state is populated enough for creation */
  
      /* a single buffer is used so we can calculate the checksum over the
       * entire 64KB block */
      buffer = g_malloc0(VHDX_HEADER_BLOCK_SIZE);
      region_table = buffer;
      offset += sizeof(VHDXRegionTableHeader);
      rt_bat = buffer + offset;
      offset += sizeof(VHDXRegionTableEntry);
      rt_metadata  = buffer + offset;
  
      region_table->signature = VHDX_REGION_SIGNATURE;
      region_table->entry_count = 2;   /* BAT and Metadata */
  
      rt_bat->guid        = bat_guid;
      rt_bat->length      = ROUND_UP(s->bat_entries * sizeof(VHDXBatEntry), MiB);
      rt_bat->file_offset = ROUND_UP(VHDX_HEADER_SECTION_END + log_size, MiB);
      s->bat_offset = rt_bat->file_offset;
  
      rt_metadata->guid        = metadata_guid;
      rt_metadata->file_offset = ROUND_UP(rt_bat->file_offset + rt_bat->length,
                                          MiB);
      rt_metadata->length      = 1 * MiB; /* min size, and more than enough */
      *metadata_offset = rt_metadata->file_offset;
  
      bat_file_offset = rt_bat->file_offset;
      bat_length = rt_bat->length;
  
      vhdx_region_header_le_export(region_table);
      vhdx_region_entry_le_export(rt_bat);
      vhdx_region_entry_le_export(rt_metadata);
  
      vhdx_update_checksum(buffer, VHDX_HEADER_BLOCK_SIZE,
                           offsetof(VHDXRegionTableHeader, checksum));
  
  
      /* The region table gives us the data we need to create the BAT,
       * so do that now */
      ret = vhdx_create_bat(blk, s, image_size, type, use_zero_blocks,
                            bat_file_offset, bat_length, errp);
      if (ret < 0) {
          goto exit;
      }
  
      /* Now write out the region headers to disk */
      ret = blk_pwrite(blk, VHDX_REGION_TABLE_OFFSET, buffer,
                       VHDX_HEADER_BLOCK_SIZE, 0);
      if (ret < 0) {
          error_setg_errno(errp, -ret, "Failed to write first region table");
          goto exit;
      }
  
      ret = blk_pwrite(blk, VHDX_REGION_TABLE2_OFFSET, buffer,
                       VHDX_HEADER_BLOCK_SIZE, 0);
      if (ret < 0) {
          error_setg_errno(errp, -ret, "Failed to write second region table");
          goto exit;
      }
  
  exit:
      g_free(s);
      g_free(buffer);
      return ret;
  }
  
  /* We need to create the following elements:
   *
   *    .-----------------------------------------------------------------.
   *    |   (A)    |   (B)    |    (C)    |     (D)       |     (E)       |
   *    |  File ID |  Header1 |  Header 2 |  Region Tbl 1 |  Region Tbl 2 |
   *    |          |          |           |               |               |
   *    .-----------------------------------------------------------------.
   *    0         64KB      128KB       192KB           256KB           320KB
   *
   *
   *    .---- ~ ----------- ~ ------------ ~ ---------------- ~ -----------.
   *    |     (F)     |     (G)       |    (H)    |                        |
   *    | Journal Log |  BAT / Bitmap |  Metadata |  .... data ......      |
   *    |             |               |           |                        |
   *    .---- ~ ----------- ~ ------------ ~ ---------------- ~ -----------.
   *   1MB
   */
  static int coroutine_fn vhdx_co_create(BlockdevCreateOptions *opts,
                                         Error **errp)
  {
      BlockdevCreateOptionsVhdx *vhdx_opts;
      BlockBackend *blk = NULL;
      BlockDriverState *bs = NULL;
  
      int ret = 0;
      uint64_t image_size;
      uint32_t log_size;
      uint32_t block_size;
      uint64_t signature;
      uint64_t metadata_offset;
      bool use_zero_blocks = false;
  
      gunichar2 *creator = NULL;
      glong creator_items;
      VHDXImageType image_type;
  
      assert(opts->driver == BLOCKDEV_DRIVER_VHDX);
      vhdx_opts = &opts->u.vhdx;
  
      /* Validate options and set default values */
      image_size = vhdx_opts->size;
      if (image_size > VHDX_MAX_IMAGE_SIZE) {
          error_setg(errp, "Image size too large; max of 64TB");
          return -EINVAL;
      }
  
      if (!vhdx_opts->has_log_size) {
          log_size = DEFAULT_LOG_SIZE;
      } else {
          if (vhdx_opts->log_size > UINT32_MAX) {
              error_setg(errp, "Log size must be smaller than 4 GB");
              return -EINVAL;
          }
          log_size = vhdx_opts->log_size;
      }
      if (log_size < MiB || (log_size % MiB) != 0) {
          error_setg(errp, "Log size must be a multiple of 1 MB");
          return -EINVAL;
      }
  
      if (!vhdx_opts->has_block_state_zero) {
          use_zero_blocks = true;
      } else {
          use_zero_blocks = vhdx_opts->block_state_zero;
      }
  
      if (!vhdx_opts->has_subformat) {
          vhdx_opts->subformat = BLOCKDEV_VHDX_SUBFORMAT_DYNAMIC;
      }
  
      switch (vhdx_opts->subformat) {
      case BLOCKDEV_VHDX_SUBFORMAT_DYNAMIC:
          image_type = VHDX_TYPE_DYNAMIC;
          break;
      case BLOCKDEV_VHDX_SUBFORMAT_FIXED:
          image_type = VHDX_TYPE_FIXED;
          break;
      default:
          g_assert_not_reached();
      }
  
      /* These are pretty arbitrary, and mainly designed to keep the BAT
       * size reasonable to load into RAM */
      if (vhdx_opts->has_block_size) {
          block_size = vhdx_opts->block_size;
      } else {
          if (image_size > 32 * TiB) {
              block_size = 64 * MiB;
          } else if (image_size > (uint64_t) 100 * GiB) {
              block_size = 32 * MiB;
          } else if (image_size > 1 * GiB) {
              block_size = 16 * MiB;
          } else {
              block_size = 8 * MiB;
          }
      }
  
      if (block_size < MiB || (block_size % MiB) != 0) {
          error_setg(errp, "Block size must be a multiple of 1 MB");
          return -EINVAL;
      }
      if (!is_power_of_2(block_size)) {
          error_setg(errp, "Block size must be a power of two");
          return -EINVAL;
      }
      if (block_size > VHDX_BLOCK_SIZE_MAX) {
          error_setg(errp, "Block size must not exceed %d", VHDX_BLOCK_SIZE_MAX);
          return -EINVAL;
      }
  
      /* Create BlockBackend to write to the image */
      bs = bdrv_open_blockdev_ref(vhdx_opts->file, errp);
      if (bs == NULL) {
          return -EIO;
      }
  
      blk = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
      ret = blk_insert_bs(blk, bs, errp);
      if (ret < 0) {
          goto delete_and_exit;
      }
      blk_set_allow_write_beyond_eof(blk, true);
  
      /* Create (A) */
  
      /* The creator field is optional, but may be useful for
       * debugging / diagnostics */
      creator = g_utf8_to_utf16("QEMU v" QEMU_VERSION, -1, NULL,
                                &creator_items, NULL);
      signature = cpu_to_le64(VHDX_FILE_SIGNATURE);
      ret = blk_pwrite(blk, VHDX_FILE_ID_OFFSET, &signature, sizeof(signature),
                       0);
      if (ret < 0) {
          error_setg_errno(errp, -ret, "Failed to write file signature");
          goto delete_and_exit;
      }
      if (creator) {
          ret = blk_pwrite(blk, VHDX_FILE_ID_OFFSET + sizeof(signature),
                           creator, creator_items * sizeof(gunichar2), 0);
          if (ret < 0) {
              error_setg_errno(errp, -ret, "Failed to write creator field");
              goto delete_and_exit;
          }
      }
  
  
      /* Creates (B),(C) */
      ret = vhdx_create_new_headers(blk, image_size, log_size);
      if (ret < 0) {
          error_setg_errno(errp, -ret, "Failed to write image headers");
          goto delete_and_exit;
      }
  
      /* Creates (D),(E),(G) explicitly. (F) created as by-product */
      ret = vhdx_create_new_region_table(blk, image_size, block_size, 512,
                                         log_size, use_zero_blocks, image_type,
                                         &metadata_offset, errp);
      if (ret < 0) {
          goto delete_and_exit;
      }
  
      /* Creates (H) */
      ret = vhdx_create_new_metadata(blk, image_size, block_size, 512,
                                     metadata_offset, image_type);
      if (ret < 0) {
          error_setg_errno(errp, -ret, "Failed to initialize metadata");
          goto delete_and_exit;
      }
  
      ret = 0;
  delete_and_exit:
      blk_unref(blk);
      bdrv_unref(bs);
      g_free(creator);
      return ret;
  }
  
  static int coroutine_fn vhdx_co_create_opts(const char *filename,
                                              QemuOpts *opts,
                                              Error **errp)
  {
      BlockdevCreateOptions *create_options = NULL;
      QDict *qdict;
      Visitor *v;
      BlockDriverState *bs = NULL;
      Error *local_err = NULL;
      int ret;
  
      static const QDictRenames opt_renames[] = {
          { VHDX_BLOCK_OPT_LOG_SIZE,      "log-size" },
          { VHDX_BLOCK_OPT_BLOCK_SIZE,    "block-size" },
          { VHDX_BLOCK_OPT_ZERO,          "block-state-zero" },
          { NULL, NULL },
      };
  
      /* Parse options and convert legacy syntax */
      qdict = qemu_opts_to_qdict_filtered(opts, NULL, &vhdx_create_opts, true);
  
      if (!qdict_rename_keys(qdict, opt_renames, errp)) {
          ret = -EINVAL;
          goto fail;
      }
  
      /* Create and open the file (protocol layer) */
      ret = bdrv_create_file(filename, opts, &local_err);
      if (ret < 0) {
          error_propagate(errp, local_err);
          goto fail;
      }
  
      bs = bdrv_open(filename, NULL, NULL,
                     BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL, errp);
      if (bs == NULL) {
          ret = -EIO;
          goto fail;
      }
  
      /* Now get the QAPI type BlockdevCreateOptions */
      qdict_put_str(qdict, "driver", "vhdx");
      qdict_put_str(qdict, "file", bs->node_name);
  
      v = qobject_input_visitor_new_flat_confused(qdict, errp);
      if (!v) {
          ret = -EINVAL;
          goto fail;
      }
  
      visit_type_BlockdevCreateOptions(v, NULL, &create_options, &local_err);
      visit_free(v);
  
      if (local_err) {
          error_propagate(errp, local_err);
          ret = -EINVAL;
          goto fail;
      }
  
      /* Silently round up sizes:
       * The image size is rounded to 512 bytes. Make the block and log size
       * close to what was specified, but must be at least 1MB, and a multiple of
       * 1 MB. Also respect VHDX_BLOCK_SIZE_MAX for block sizes. block_size = 0
       * means auto, which is represented by a missing key in QAPI. */
      assert(create_options->driver == BLOCKDEV_DRIVER_VHDX);
      create_options->u.vhdx.size =
          ROUND_UP(create_options->u.vhdx.size, BDRV_SECTOR_SIZE);
  
      if (create_options->u.vhdx.has_log_size) {
          create_options->u.vhdx.log_size =
              ROUND_UP(create_options->u.vhdx.log_size, MiB);
      }
      if (create_options->u.vhdx.has_block_size) {
          create_options->u.vhdx.block_size =
              ROUND_UP(create_options->u.vhdx.block_size, MiB);
  
          if (create_options->u.vhdx.block_size == 0) {
              create_options->u.vhdx.has_block_size = false;
          }
          if (create_options->u.vhdx.block_size > VHDX_BLOCK_SIZE_MAX) {
              create_options->u.vhdx.block_size = VHDX_BLOCK_SIZE_MAX;
          }
      }
  
      /* Create the vhdx image (format layer) */
      ret = vhdx_co_create(create_options, errp);
  
  fail:
      qobject_unref(qdict);
      bdrv_unref(bs);
      qapi_free_BlockdevCreateOptions(create_options);
      return ret;
  }
  
  /* If opened r/w, the VHDX driver will automatically replay the log,
   * if one is present, inside the vhdx_open() call.
   *
   * If qemu-img check -r all is called, the image is automatically opened
   * r/w and any log has already been replayed, so there is nothing (currently)
   * for us to do here
   */
  static int coroutine_fn vhdx_co_check(BlockDriverState *bs,
                                        BdrvCheckResult *result,
                                        BdrvCheckMode fix)
  {
      BDRVVHDXState *s = bs->opaque;
  
      if (s->log_replayed_on_open) {
          result->corruptions_fixed++;
      }
      return 0;
  }
  
  static QemuOptsList vhdx_create_opts = {
      .name = "vhdx-create-opts",
      .head = QTAILQ_HEAD_INITIALIZER(vhdx_create_opts.head),
      .desc = {
          {
             .name = BLOCK_OPT_SIZE,
             .type = QEMU_OPT_SIZE,
             .help = "Virtual disk size; max of 64TB."
         },
         {
             .name = VHDX_BLOCK_OPT_LOG_SIZE,
             .type = QEMU_OPT_SIZE,
             .def_value_str = stringify(DEFAULT_LOG_SIZE),
             .help = "Log size; min 1MB."
         },
         {
             .name = VHDX_BLOCK_OPT_BLOCK_SIZE,
             .type = QEMU_OPT_SIZE,
             .def_value_str = stringify(0),
             .help = "Block Size; min 1MB, max 256MB. " \
                     "0 means auto-calculate based on image size."
         },
         {
             .name = BLOCK_OPT_SUBFMT,
             .type = QEMU_OPT_STRING,
             .help = "VHDX format type, can be either 'dynamic' or 'fixed'. "\
                     "Default is 'dynamic'."
         },
         {
             .name = VHDX_BLOCK_OPT_ZERO,
             .type = QEMU_OPT_BOOL,
             .help = "Force use of payload blocks of type 'ZERO'. "\
                     "Non-standard, but default.  Do not set to 'off' when "\
                     "using 'qemu-img convert' with subformat=dynamic."
         },
         { NULL }
      }
  };
  
  static BlockDriver bdrv_vhdx = {
      .format_name            = "vhdx",
      .instance_size          = sizeof(BDRVVHDXState),
      .bdrv_probe             = vhdx_probe,
      .bdrv_open              = vhdx_open,
      .bdrv_close             = vhdx_close,
      .bdrv_reopen_prepare    = vhdx_reopen_prepare,
      .bdrv_child_perm        = bdrv_format_default_perms,
      .bdrv_co_readv          = vhdx_co_readv,
      .bdrv_co_writev         = vhdx_co_writev,
      .bdrv_co_create         = vhdx_co_create,
      .bdrv_co_create_opts    = vhdx_co_create_opts,
      .bdrv_get_info          = vhdx_get_info,
      .bdrv_co_check          = vhdx_co_check,
      .bdrv_has_zero_init     = bdrv_has_zero_init_1,
  
      .create_opts            = &vhdx_create_opts,
  };
  
  static void bdrv_vhdx_init(void)
  {
      bdrv_register(&bdrv_vhdx);
  }
  
  block_init(bdrv_vhdx_init);
  