Re: [libvirt] [PATCH 2/2] Storage : Fix cloning of raw, sparse volumes

On Mon, Jun 22, 2015 at 05:09:18PM +0530, Prerna Saxena wrote: > From: Prerna Saxena <prerna(a)linux.vnet.ibm.com&gt; > Date: Mon, 22 Jun 2015 02:54:32 -0500 > > 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(a)linux.vnet.ibm.com&gt; > --- > src/storage/storage_backend.c | 10 +++++----- > src/storage/storage_driver.c | 5 ----- > 2 files changed, 5 insertions(+), 10 deletions(-) > > diff --git a/src/storage/storage_backend.c b/src/storage/storage_backend.c > index ce59f63..c99b718 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, > @@ -397,7 +397,7 @@ createRawFile(int fd, virStorageVolDefPtr vol, > virStorageVolDefPtr inputvol, > bool reflink_copy) > { > - bool need_alloc = true; > + bool need_alloc = !(inputvol && (inputvol->target.capacity > inputvol->target.allocation)); Comparing 'inputvol->target.capacity > vol->target.allocation' would allow creating a sparse volume from a non-sparse one and vice-versa by specifying the correct allocation.

> int ret = 0; > unsigned long long remain; > > @@ -420,7 +420,7 @@ 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) { > @@ -433,14 +433,14 @@ createRawFile(int fd, virStorageVolDefPtr vol, > } > #endif > > - remain = vol->target.allocation; > + remain = vol->target.capacity; > > if (inputvol) { > /* 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); > + (inputvol->target.allocation < inputvol->target.capacity); If allocation < capacity, then need_alloc is already false.