[libvirt] [PATCHv4 2/2] Fix cloning of raw, sparse volumes

John Ferlan jferlan at redhat.com
Thu Jul 9 14:42:49 UTC 2015



On 07/03/2015 09:54 AM, Ján Tomko wrote:
> From: Prerna Saxena <prerna at linux.vnet.ibm.com>
> 
> When virsh vol-clone is attempted on a raw file where capacity > allocation,
> the resulting cloned volume has a size that matches the virtual-size of
> the parent; in place of matching its actual, disk size.
> This patch fixes the cloned disk to have same _allocated_size_ as
> the parent file from which it was cloned.
> 
> Ref: http://www.redhat.com/archives/libvir-list/2015-May/msg00050.html
> 
> Also fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1130739
> 
> Signed-off-by: Prerna Saxena <prerna at linux.vnet.ibm.com>
> Signed-off-by: Ján Tomko <jtomko at redhat.com>
> ---
>  src/storage/storage_backend.c | 23 ++++++++++++++---------
>  src/storage/storage_driver.c  |  5 -----
>  2 files changed, 14 insertions(+), 14 deletions(-)
> 
> diff --git a/src/storage/storage_backend.c b/src/storage/storage_backend.c
> index c71545c..bab81e3 100644
> --- a/src/storage/storage_backend.c
> +++ b/src/storage/storage_backend.c
> @@ -342,7 +342,7 @@ virStorageBackendCreateBlockFrom(virConnectPtr conn ATTRIBUTE_UNUSED,
>          goto cleanup;
>      }
>  
> -    remain = vol->target.allocation;
> +    remain = vol->target.capacity;
>  
>      if (inputvol) {
>          int res = virStorageBackendCopyToFD(vol, inputvol,
> @@ -401,6 +401,12 @@ createRawFile(int fd, virStorageVolDefPtr vol,
>      int ret = 0;
>      unsigned long long pos = 0;
>  
> +    /* If the new allocation is lower than the capacity of the orignal file,

s/orignal/original

ACK series


John

> +     * the cloned volume will be sparse */
> +    if (inputvol &&
> +        vol->target.allocation < inputvol->target.capacity)
> +        need_alloc = false;
> +
>      /* Seek to the final size, so the capacity is available upfront
>       * for progress reporting */
>      if (ftruncate(fd, vol->target.capacity) < 0) {
> @@ -420,7 +426,7 @@ createRawFile(int fd, virStorageVolDefPtr vol,
>       * to writing zeroes block by block in case fallocate isn't
>       * available, and since we're going to copy data from another
>       * file it doesn't make sense to write the file twice. */
> -    if (vol->target.allocation) {
> +    if (vol->target.allocation && need_alloc) {
>          if (fallocate(fd, 0, 0, vol->target.allocation) == 0) {
>              need_alloc = false;
>          } else if (errno != ENOSYS && errno != EOPNOTSUPP) {
> @@ -433,21 +439,20 @@ createRawFile(int fd, virStorageVolDefPtr vol,
>      }
>  #endif
>  
> -
>      if (inputvol) {
> -        unsigned long long remain = vol->target.allocation;
> +        unsigned long long remain = inputvol->target.capacity;
>          /* allow zero blocks to be skipped if we've requested sparse
>           * allocation (allocation < capacity) or we have already
>           * been able to allocate the required space. */
> -        bool want_sparse = !need_alloc ||
> -            (vol->target.allocation < inputvol->target.capacity);
> -
>          ret = virStorageBackendCopyToFD(vol, inputvol, fd, &remain,
> -                                        want_sparse, reflink_copy);
> +                                        !need_alloc, reflink_copy);
>          if (ret < 0)
>              goto cleanup;
>  
> -        pos = vol->target.allocation - remain;
> +        /* If the new allocation is greater than the original capacity,
> +         * but fallocate failed, fill the rest with zeroes.
> +         */
> +        pos = inputvol->target.capacity - remain;
>      }
>  
>      if (need_alloc) {
> diff --git a/src/storage/storage_driver.c b/src/storage/storage_driver.c
> index e600514..ba27acf 100644
> --- a/src/storage/storage_driver.c
> +++ b/src/storage/storage_driver.c
> @@ -1975,11 +1975,6 @@ storageVolCreateXMLFrom(virStoragePoolPtr obj,
>      if (newvol->target.capacity < origvol->target.capacity)
>          newvol->target.capacity = origvol->target.capacity;
>  
> -    /* Make sure allocation is at least as large as the destination cap,
> -     * to make absolutely sure we copy all possible contents */
> -    if (newvol->target.allocation < origvol->target.capacity)
> -        newvol->target.allocation = origvol->target.capacity;
> -
>      if (!backend->buildVolFrom) {
>          virReportError(VIR_ERR_NO_SUPPORT,
>                         "%s", _("storage pool does not support"
> 




More information about the libvir-list mailing list