On 09/02/2014 12:04 PM, Prerna Saxena wrote:
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.
For example : Given this image:
[root@localhost]# qemu-img info /var/lib/libvirt/images/f20.raw
image: /var/lib/libvirt/images/f20.raw
file format: raw
virtual size: 2.0G (2147483648 bytes)
disk size: 617M
When this disk is copied using virsh vol-clone :
[root@localhost~] vol-clone --vol f20.raw --newname f20-copy.raw
--pool default
Vol f20-copy.raw cloned from f20.raw
[root@localhost~]
The characteristics of the cloned disk differ in "disk size".
Its allocated disk size is more than the allocated size of parent file;
which is an anomaly. It has picked up an allocated size matching
the parent's virtual size.
[root@localhost~] qemu-img info /var/lib/libvirt/images/f20-copy.raw
image: /var/lib/libvirt/images/f20-copy.raw
file format: raw
virtual size: 2.0G (2147483648 bytes)
disk size: 2.0G
This patch fixes the cloned disk to have same _allocated_size_ as
the parent file from which it was cloned.
A bug has been filed for this recently:
https://bugzilla.redhat.com/show_bug.cgi?id=1130739
It would be nice to mention it in the commit message.
Signed-off-by: Prerna Saxena <prerna(a)linux.vnet.ibm.com>
---
src/storage/storage_driver.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/src/storage/storage_driver.c b/src/storage/storage_driver.c
index 433d7b7..930b45a 100644
--- a/src/storage/storage_driver.c
+++ b/src/storage/storage_driver.c
@@ -1821,11 +1821,6 @@ 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;
-
This essentially reverts commit 5ea25b7 [1], which means requesting a clone
with <allocation> less than <capacity> will result in only the first
<allocation> bytes being copied, thus losing any data after that point.
The virStorageBackendCopyToFD call in createRawFile also needs to be adjusted
to copy the non-zero data after the 'allocation' position.
if (!backend->buildVolFrom) {
virReportError(VIR_ERR_NO_SUPPORT,
"%s", _("storage pool does not support volume
creation from an existing volume"));
Jan
[1]
http://libvirt.org/git/?p=libvirt.git;a=commitdiff;h=5ea25b7