Re: [Qemu-devel] [PATCH v6 04/12] VMDK: separate vmdk_open by format version

[Kevin Wolf]

Am 01.07.2011 06:55, schrieb Fam Zheng:
> Separate vmdk_open by subformats to:
> * vmdk_open_vmdk3
> * vmdk_open_vmdk4
> 
> Signed-off-by: Fam Zheng <address@hidden>
> ---
>  block/vmdk.c |  197 ++++++++++++++++++++++++++++++++++++++-------------------
>  1 files changed, 131 insertions(+), 66 deletions(-)
> 
> diff --git a/block/vmdk.c b/block/vmdk.c
> index 4684670..03248f3 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -456,74 +456,26 @@ static VmdkExtent *vmdk_add_extent(BlockDriverState *bs,
>      return extent;
>  }
>  
> -
> -static int vmdk_open(BlockDriverState *bs, int flags)
> +static int vmdk_init_tables(BlockDriverState *bs, VmdkExtent *extent)
>  {
> -    BDRVVmdkState *s = bs->opaque;
> -    uint32_t magic;
> -    int i;
> -    uint32_t l1_size, l1_entry_sectors;
> -    VmdkExtent *extent = NULL;
> -
> -    if (bdrv_pread(bs->file, 0, &magic, sizeof(magic)) != sizeof(magic))
> -        goto fail;
> -
> -    magic = be32_to_cpu(magic);
> -    if (magic == VMDK3_MAGIC) {
> -        VMDK3Header header;
> -        if (bdrv_pread(bs->file, sizeof(magic), &header, sizeof(header))
> -                != sizeof(header)) {
> -            goto fail;
> -        }
> -        extent = vmdk_add_extent(bs, bs->file, false,
> -                              le32_to_cpu(header.disk_sectors),
> -                              le32_to_cpu(header.l1dir_offset) << 9, 0,
> -                              1 << 6, 1 << 9, 
> le32_to_cpu(header.granularity));
> -    } else if (magic == VMDK4_MAGIC) {
> -        VMDK4Header header;
> -        if (bdrv_pread(bs->file, sizeof(magic), &header, sizeof(header))
> -                != sizeof(header)) {
> -            goto fail;
> -        }
> -        l1_entry_sectors = le32_to_cpu(header.num_gtes_per_gte)
> -                            * le64_to_cpu(header.granularity);
> -        l1_size = (le64_to_cpu(header.capacity) + l1_entry_sectors - 1)
> -                    / l1_entry_sectors;
> -        extent = vmdk_add_extent(bs, 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) {
> -            goto fail;
> -        }
> -        // try to open parent images, if exist
> -        if (vmdk_parent_open(bs) != 0)
> -            goto fail;
> -        // write the CID once after the image creation
> -        s->parent_cid = vmdk_read_cid(bs,1);
> -    } else {
> -        goto fail;
> -    }
> -
> -    /* sum up the total sectors */
> -    bs->total_sectors = 0;
> -    for (i = 0; i < s->num_extents; i++) {
> -        bs->total_sectors += s->extents[i].sectors;
> -    }
> +    int ret;
> +    int l1_size, i;
>  
>      /* read the L1 table */
>      l1_size = extent->l1_size * sizeof(uint32_t);
>      extent->l1_table = qemu_malloc(l1_size);
> -    if (bdrv_pread(bs->file,
> -            extent->l1_table_offset,
> -            extent->l1_table,
> -            l1_size)
> -        != l1_size) {
> +    if (!extent->l1_table) {
> +        ret = -ENOMEM;
>          goto fail;
>      }

qemu_malloc() never fails, so you don't need this check.

> +    ret = bdrv_pread(bs->file,
> +                extent->l1_table_offset,
> +                extent->l1_table,
> +                l1_size);
> +    if (ret != l1_size) {
> +        ret = ret < 0 ? ret : -EIO;
> +        goto fail_l1;
> +    }

bdrv_pread only ever returns 0 for success or -errno for errors. So you
can simplify the code like this:

ret = bdrv_pread(...);
if (ret < 0) {
    goto fail_l1;
}

You have the same pattern in other places, too.

>      for (i = 0; i < extent->l1_size; i++) {
>          le32_to_cpus(&extent->l1_table[i]);
>      }
> @@ -538,16 +490,129 @@ static int vmdk_open(BlockDriverState *bs, int flags)
>              goto fail;
>          }
>          for (i = 0; i < extent->l1_size; i++) {
> +            if (!extent->l1_backup_table) {
> +                ret = -ENOMEM;
> +                goto fail_l1;
> +            }
> +        }

Hm, isn't this checking the same thing multiple times?

Anyway, qemu_malloc() still doesn't fail. ;-)

> +        ret = bdrv_pread(bs->file,
> +                            extent->l1_backup_table_offset,
> +                            extent->l1_backup_table,
> +                            l1_size);

This duplicates a read from a few lines above. Mismerge?

> +        if (ret != l1_size) {
> +                ret = ret < 0 ? ret : -EIO;
> +            goto fail;
> +        }
> +        for (i = 0; i < extent->l1_size; i++) {
>              le32_to_cpus(&extent->l1_backup_table[i]);
>          }
>      }
>  
>      extent->l2_cache =
>          qemu_malloc(extent->l2_size * L2_CACHE_SIZE * sizeof(uint32_t));
> +    if (!extent->l2_cache) {
> +        ret = -ENOMEM;
> +        goto fail_l1b;
> +    }

Unnecessary check.

>      return 0;
> + fail_l1b:
> +    qemu_free(extent->l1_backup_table);
> + fail_l1:
> +    qemu_free(extent->l1_table);
>   fail:
> -    vmdk_free_extents(bs);
> -    return -1;
> +    return ret;
> +}
> +
> +static int vmdk_open_vmdk3(BlockDriverState *bs, int flags)
> +{
> +    int ret;
> +    uint32_t magic;
> +    VMDK3Header header;
> +    VmdkExtent *extent;
> +    BDRVVmdkState *s = bs->opaque;
> +
> +    ret = bdrv_pread(bs->file, sizeof(magic), &header, sizeof(header));
> +    if (ret != sizeof(header)) {
> +        ret = ret < 0 ? ret : -EIO;
> +        goto fail;
> +    }
> +    extent = vmdk_add_extent(bs,
> +                             bs->file, false,
> +                             le32_to_cpu(header.disk_sectors),
> +                             le32_to_cpu(header.l1dir_offset) << 9,
> +                             0, 1 << 6, 1 << 9,
> +                             le32_to_cpu(header.granularity));
> +    ret = vmdk_init_tables(bs, extent);
> +    if (ret) {
> +        return ret;

Are the extents leaked here?

> +    }
> +    return 0;
> + fail:
> +    qemu_free(s->extents);

Why not vmdk_free_extents? Does this leak the tables/caches?

> +    return ret;
> +}
> +
> +static int vmdk_open_vmdk4(BlockDriverState *bs, int flags)
> +{
> +    int ret;
> +    uint32_t magic;
> +    uint32_t l1_size, l1_entry_sectors;
> +    VMDK4Header header;
> +    BDRVVmdkState *s = bs->opaque;
> +    VmdkExtent *extent;
> +
> +    ret = bdrv_pread(bs->file, sizeof(magic), &header, sizeof(header));
> +    if (ret != sizeof(header)) {
> +        ret = ret < 0 ? ret : -EIO;
> +        goto fail;
> +    }
> +    l1_entry_sectors = le32_to_cpu(header.num_gtes_per_gte)
> +                        * le64_to_cpu(header.granularity);
> +    l1_size = (le64_to_cpu(header.capacity) + l1_entry_sectors - 1)
> +                / l1_entry_sectors;
> +    extent = vmdk_add_extent(bs, 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;
> +    }
> +    return 0;
> + fail:
> +    qemu_free(s->extents);
> +    return ret;
> +}

The same comments as for the version 3 function apply.

> +
> +static int vmdk_open(BlockDriverState *bs, int flags)
> +{
> +    uint32_t magic;
> +
> +    if (bdrv_pread(bs->file, 0, &magic, sizeof(magic)) != sizeof(magic)) {
> +        return -EIO;
> +    }
> +
> +    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);
> +    } else {
> +        return -EINVAL;
> +    }
>  }
>  
>  static int get_whole_cluster(BlockDriverState *bs,
> @@ -634,11 +699,11 @@ static uint64_t get_cluster_offset(BlockDriverState *bs,
>      if (!l2_offset) {
>          return 0;
>      }
> -    for(i = 0; i < L2_CACHE_SIZE; i++) {
> +    for (i = 0; i < L2_CACHE_SIZE; i++) {
>          if (l2_offset == extent->l2_cache_offsets[i]) {
>              /* increment the hit count */
>              if (++extent->l2_cache_counts[i] == 0xffffffff) {
> -                for(j = 0; j < L2_CACHE_SIZE; j++) {
> +                for (j = 0; j < L2_CACHE_SIZE; j++) {
>                      extent->l2_cache_counts[j] >>= 1;
>                  }
>              }
> @@ -649,7 +714,7 @@ static uint64_t get_cluster_offset(BlockDriverState *bs,
>      /* not found: load a new entry in the least used one */
>      min_index = 0;
>      min_count = 0xffffffff;
> -    for(i = 0; i < L2_CACHE_SIZE; i++) {
> +    for (i = 0; i < L2_CACHE_SIZE; i++) {
>          if (extent->l2_cache_counts[i] < min_count) {
>              min_count = extent->l2_cache_counts[i];
>              min_index = i;

Kevin