Re: [Qemu-devel] [PATCH 2/6] VMDK: add twoGbMaxExtentSparse support

[Fam Zheng]

On Tue, Aug 2, 2011 at 6:32 PM, Stefan Hajnoczi <address@hidden> wrote:
> On Wed, Jul 27, 2011 at 10:27 AM, Fam Zheng <address@hidden> wrote:
>> Add twoGbMaxExtentSparse support. Only opening code is changed.
>>
>> Signed-off-by: Fam Zheng <address@hidden>
>> ---
>>  block/vmdk.c |  124 
>> ++++++++++++++++++++++++++++++++++++----------------------
>>  1 files changed, 77 insertions(+), 47 deletions(-)
>>
>> diff --git a/block/vmdk.c b/block/vmdk.c
>> index 9e6c67a..9d1ae32 100644
>> --- a/block/vmdk.c
>> +++ b/block/vmdk.c
>> @@ -357,7 +357,9 @@ static int vmdk_init_tables(BlockDriverState *bs, 
>> VmdkExtent *extent)
>>     return ret;
>>  }
>>
>> -static int vmdk_open_vmdk3(BlockDriverState *bs, int flags)
>> +static int vmdk_open_vmdk3(BlockDriverState *bs,
>> +                           BlockDriverState *file,
>> +                           int flags)
>>  {
>>     int ret;
>>     uint32_t magic;
>> @@ -365,10 +367,9 @@ static int vmdk_open_vmdk3(BlockDriverState *bs, int 
>> flags)
>>     BDRVVmdkState *s = bs->opaque;
>>     VmdkExtent *extent;
>>
>> -    s->desc_offset = 0x200;
>> -    ret = bdrv_pread(bs->file, sizeof(magic), &header, sizeof(header));
>> +    ret = bdrv_pread(file, sizeof(magic), &header, sizeof(header));
>>     if (ret < 0) {
>> -        goto fail;
>> +        return ret;
>>     }
>>     extent = vmdk_add_extent(bs,
>>                              bs->file, false,
>> @@ -378,17 +379,16 @@ static int vmdk_open_vmdk3(BlockDriverState *bs, int 
>> flags)
>>                              le32_to_cpu(header.granularity));
>>     ret = vmdk_init_tables(bs, extent);
>>     if (ret) {
>> -        /* vmdk_init_tables cleans up on fail, so only free allocation of
>> -         * vmdk_add_extent here. */
>> -        goto fail;
>> +        /* free extent allocated by vmdk_add_extent */
>> +        s->num_extents--;
>> +        qemu_realloc(s->extents, s->num_extents * sizeof(VmdkExtent));
>
> The return value of qemu_realloc() is the new address of s->extents[].
>  You are ignoring the new address and continue to use the old one.
>
> Please add a vmdk_free_last_extent() function that encapsulates this.
> The rest of the vmdk.c code should not manipulate
> s->extents[]/s->num_extents.  Use vmdk_add_extent(),
> vmdk_free_last_extent(), vmdk_free_extents() instead of spreading the
> extent management code in various places.
>
>>     }
>> -    return 0;
>> - fail:
>> -    vmdk_free_extents(bs);
>>     return ret;
>>  }
>>
>> -static int vmdk_open_vmdk4(BlockDriverState *bs, int flags)
>> +static int vmdk_open_vmdk4(BlockDriverState *bs,
>> +                           BlockDriverState *file,
>> +                           int flags)
>>  {
>>     int ret;
>>     uint32_t magic;
>> @@ -397,39 +397,30 @@ static int vmdk_open_vmdk4(BlockDriverState *bs, int 
>> flags)
>>     BDRVVmdkState *s = bs->opaque;
>>     VmdkExtent *extent;
>>
>> -    s->desc_offset = 0x200;
>> -    ret = bdrv_pread(bs->file, sizeof(magic), &header, sizeof(header));
>> +    ret = bdrv_pread(file, sizeof(magic), &header, sizeof(header));
>>     if (ret < 0) {
>> -        goto fail;
>> +        return ret;
>>     }
>>     l1_entry_sectors = le32_to_cpu(header.num_gtes_per_gte)
>>                         * le64_to_cpu(header.granularity);
>> +    if (l1_entry_sectors <= 0) {
>> +        return -EINVAL;
>> +    }
>>     l1_size = (le64_to_cpu(header.capacity) + l1_entry_sectors - 1)
>>                 / l1_entry_sectors;
>> -    extent = vmdk_add_extent(bs, bs->file, false,
>> +    extent = vmdk_add_extent(bs, file, false,
>>                           le64_to_cpu(header.capacity),
>>                           le64_to_cpu(header.gd_offset) << 9,
>>                           le64_to_cpu(header.rgd_offset) << 9,
>>                           l1_size,
>>                           le32_to_cpu(header.num_gtes_per_gte),
>>                           le64_to_cpu(header.granularity));
>> -    if (extent->l1_entry_sectors <= 0) {
>> -        ret = -EINVAL;
>> -        goto fail;
>> -    }
>> -    /* try to open parent images, if exist */
>> -    ret = vmdk_parent_open(bs);
>> -    if (ret) {
>> -        goto fail;
>> -    }
>> -    s->parent_cid = vmdk_read_cid(bs, 1);
>>     ret = vmdk_init_tables(bs, extent);
>>     if (ret) {
>> -        goto fail;
>> +        /* free extent allocated by vmdk_add_extent */
>> +        s->num_extents--;
>> +        qemu_realloc(s->extents, s->num_extents * sizeof(VmdkExtent));
>
> Same bug.
>
>>     }
>> -    return 0;
>> - fail:
>> -    vmdk_free_extents(bs);
>>     return ret;
>>  }
>>
>> @@ -460,6 +451,35 @@ static int vmdk_parse_description(const char *desc, 
>> const char *opt_name,
>>     return 0;
>>  }
>>
>> +/* Open an extent file and append to bs array */
>> +static int vmdk_open_sparse(BlockDriverState *bs,
>> +                            BlockDriverState *file,
>> +                            int flags)
>> +{
>> +    int ret;
>> +    uint32_t magic;
>> +
>> +    if (bdrv_pread(file, 0, &magic, sizeof(magic)) != sizeof(magic)) {
>> +        return -EIO;
>> +    }
>> +
>> +    magic = be32_to_cpu(magic);
>> +    if (magic == VMDK3_MAGIC) {
>> +        ret = vmdk_open_vmdk3(bs, file, flags);
>> +        if (ret) {
>> +            return ret;
>> +        }
>> +    } else if (magic == VMDK4_MAGIC) {
>> +        ret = vmdk_open_vmdk4(bs, file, flags);
>> +        if (ret) {
>> +            return ret;
>> +        }
>> +    } else {
>> +        return -EINVAL;
>> +    }
>> +    return 0;
>
> Shorter way of writing this (ret is no longer necessary):
>
> switch (magic) {
> case VMDK3_MAGIC:
>    return vmdk_open_vmdk3(bs, file, flags);
> case VMDK4_MAGIC:
>    return vmdk_open_vmdk4(bs, file, flags);
> default:
>    return -EINVAL;
> }
>
>> +}
>> +
>>  static int vmdk_parse_extents(const char *desc, BlockDriverState *bs,
>>         const char *desc_file_path)
>>  {
>> @@ -470,6 +490,8 @@ static int vmdk_parse_extents(const char *desc, 
>> BlockDriverState *bs,
>>     const char *p = desc;
>>     int64_t sectors = 0;
>>     int64_t flat_offset;
>> +    char extent_path[PATH_MAX];
>> +    BlockDriverState *extent_file;
>>
>>     while (*p) {
>>         /* parse extent line:
>> @@ -504,22 +526,28 @@ static int vmdk_parse_extents(const char *desc, 
>> BlockDriverState *bs,
>>             goto next_line;
>>         }
>>
>> +        path_combine(extent_path, sizeof(extent_path),
>> +                desc_file_path, fname);
>> +        ret = bdrv_file_open(&extent_file, extent_path, bs->open_flags);
>> +        if (ret) {
>> +            return ret;
>> +        }
>> +
>>         /* save to extents array */
>>         if (!strcmp(type, "FLAT")) {
>>             /* FLAT extent */
>> -            char extent_path[PATH_MAX];
>> -            BlockDriverState *extent_file;
>>             VmdkExtent *extent;
>>
>> -            path_combine(extent_path, sizeof(extent_path),
>> -                    desc_file_path, fname);
>> -            ret = bdrv_file_open(&extent_file, extent_path, bs->open_flags);
>> -            if (ret) {
>> -                return ret;
>> -            }
>>             extent = vmdk_add_extent(bs, extent_file, true, sectors,
>>                             0, 0, 0, 0, sectors);
>>             extent->flat_start_offset = flat_offset;
>> +        } else if (!strcmp(type, "SPARSE")) {
>> +            /* SPARSE extent */
>> +            ret = vmdk_open_sparse(bs, extent_file, bs->open_flags);
>> +            if (ret) {
>> +                bdrv_delete(extent_file);
>> +                return ret;
>> +            }
>>         } else {
>>             /* SPARSE extent, not supported for now */
>
> This comment is outdated.
>
>>             fprintf(stderr,
>> @@ -552,6 +580,7 @@ static int vmdk_open_desc_file(BlockDriverState *bs, int 
>> flags)
>>         return -EINVAL;
>>     }
>>     if (strcmp(ct, "monolithicFlat") &&
>> +        strcmp(ct, "twoGbMaxExtentSparse") &&
>>         strcmp(ct, "twoGbMaxExtentFlat")) {
>>         fprintf(stderr,
>>                 "VMDK: Not supported image type \"%s\""".\n", ct);
>> @@ -574,17 +603,18 @@ static int vmdk_open_desc_file(BlockDriverState *bs, 
>> int flags)
>>
>>  static int vmdk_open(BlockDriverState *bs, int flags)
>>  {
>> -    uint32_t magic;
>> -
>> -    if (bdrv_pread(bs->file, 0, &magic, sizeof(magic)) != sizeof(magic)) {
>> -        return -EIO;
>> -    }
>> +    int ret;
>> +    BDRVVmdkState *s = bs->opaque;
>>
>> -    magic = be32_to_cpu(magic);
>> -    if (magic == VMDK3_MAGIC) {
>> -        return vmdk_open_vmdk3(bs, flags);
>> -    } else if (magic == VMDK4_MAGIC) {
>> -        return vmdk_open_vmdk4(bs, flags);
>> +    if (vmdk_open_sparse(bs, bs->file, flags) == 0) {
>> +        s->desc_offset = 0x200;
>> +        /* try to open parent images, if exist */
>> +        ret = vmdk_parent_open(bs);
>> +        if (ret) {
>> +            return ret;
>
> What needs to be freed here?
>

No resource allocation in vmdk_parent_open, so I think none.


-- 
Best regards!
Fam Zheng