Re: [Qemu-devel] [PATCH 1/2] vmdk: support vmfsSparse files

[Andreas Färber]

Am 11.08.2013 18:13, schrieb Paolo Bonzini:
> VMware ESX hosts use a variant of the VMDK3 format, identified by the
> vmfsSparse create type ad the VMFSSPARSE extent type.

"and"?

> It has 16 KB grain tables (L2) and a variable-size grain directory (L1).
> In addition, the grain size is always 512, but that is not a problem
> because it is included in the header.
> 
> The format of the extents is documented in the VMDK spec.  The format
> of the descriptor file is not documented precisely, but it can be
> found at http://kb.vmware.com/kb/10026353 (Recreating a missing virtual
> machine disk (VMDK) descriptor file for delta disks).
> 
> With these patches, vmfsSparse files only work if opened through the
> descriptor file.  Data files without descriptor files, as far as I
> could understand, are not supported by ESX.
> 
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
>  block/vmdk.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++-----
>  1 file changed, 46 insertions(+), 5 deletions(-)
> 
> diff --git a/block/vmdk.c b/block/vmdk.c
> index b16d509..eaf484a 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -505,6 +505,34 @@ static int vmdk_open_vmdk3(BlockDriverState *bs,
>      return ret;
>  }
>  
> +static int vmdk_open_vmfs_sparse(BlockDriverState *bs,
> +                                 BlockDriverState *file,
> +                                 int flags)
> +{
> +    int ret;
> +    uint32_t magic;
> +    VMDK3Header header;
> +    VmdkExtent *extent;
> +
> +    ret = bdrv_pread(file, sizeof(magic), &header, sizeof(header));
> +    if (ret < 0) {
> +        return ret;
> +    }
> +    extent = vmdk_add_extent(bs, file, false,
> +                          le64_to_cpu(header.disk_sectors),
> +                          le64_to_cpu(header.l1dir_offset) << 9,
> +                          0,
> +                          le64_to_cpu(header.l1dir_size) * 4,
> +                          4096,
> +                          le64_to_cpu(header.granularity)); /* always 512 */

Indentation is 3 off (guessing the variable was called ext before ;)).

Andreas

> +    ret = vmdk_init_tables(bs, extent);
> +    if (ret) {
> +        /* free extent allocated by vmdk_add_extent */
> +        vmdk_free_last_extent(bs);
> +    }
> +    return ret;
> +}
> +
>  static int vmdk_open_desc_file(BlockDriverState *bs, int flags,
>                                 uint64_t desc_offset);
>  
> @@ -663,7 +691,7 @@ static int vmdk_parse_description(const char *desc, const 
> char *opt_name,
>  /* Open an extent file and append to bs array */
>  static int vmdk_open_sparse(BlockDriverState *bs,
>                              BlockDriverState *file,
> -                            int flags)
> +                            int flags, bool vmfs_sparse)
>  {
>      uint32_t magic;
>  
> @@ -674,7 +702,11 @@ static int vmdk_open_sparse(BlockDriverState *bs,
>      magic = be32_to_cpu(magic);
>      switch (magic) {
>          case VMDK3_MAGIC:
> -            return vmdk_open_vmdk3(bs, file, flags);
> +            if (vmfs_sparse) {
> +                return vmdk_open_vmfs_sparse(bs, file, flags);
> +            } else {
> +                return vmdk_open_vmdk3(bs, file, flags);
> +            }
>              break;
>          case VMDK4_MAGIC:
>              return vmdk_open_vmdk4(bs, file, flags);
> @@ -718,7 +750,8 @@ static int vmdk_parse_extents(const char *desc, 
> BlockDriverState *bs,
>          }
>  
>          if (sectors <= 0 ||
> -            (strcmp(type, "FLAT") && strcmp(type, "SPARSE")) ||
> +            (strcmp(type, "FLAT") && strcmp(type, "SPARSE") &&
> +             strcmp(type, "VMFSSPARSE")) ||
>              (strcmp(access, "RW"))) {
>              goto next_line;
>          }
> @@ -743,7 +776,14 @@ static int vmdk_parse_extents(const char *desc, 
> BlockDriverState *bs,
>              extent->flat_start_offset = flat_offset << 9;
>          } else if (!strcmp(type, "SPARSE")) {
>              /* SPARSE extent */
> -            ret = vmdk_open_sparse(bs, extent_file, bs->open_flags);
> +            ret = vmdk_open_sparse(bs, extent_file, bs->open_flags, false);
> +            if (ret) {
> +                bdrv_delete(extent_file);
> +                return ret;
> +            }
> +        } else if (!strcmp(type, "VMFSSPARSE")) {
> +            /* VMFSSPARSE extent */
> +            ret = vmdk_open_sparse(bs, extent_file, bs->open_flags, true);
>              if (ret) {
>                  bdrv_delete(extent_file);
>                  return ret;
> @@ -789,6 +829,7 @@ static int vmdk_open_desc_file(BlockDriverState *bs, int 
> flags,
>          goto exit;
>      }
>      if (strcmp(ct, "monolithicFlat") &&
> +        strcmp(ct, "vmfsSparse") &&
>          strcmp(ct, "twoGbMaxExtentSparse") &&
>          strcmp(ct, "twoGbMaxExtentFlat")) {
>          fprintf(stderr,
> @@ -808,7 +849,7 @@ static int vmdk_open(BlockDriverState *bs, QDict 
> *options, int flags)
>      int ret;
>      BDRVVmdkState *s = bs->opaque;
>  
> -    if (vmdk_open_sparse(bs, bs->file, flags) == 0) {
> +    if (vmdk_open_sparse(bs, bs->file, flags, false) == 0) {
>          s->desc_offset = 0x200;
>      } else {
>          ret = vmdk_open_desc_file(bs, flags, 0);
> 


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