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We have been trying to implement the ALLOCATE flag to mean
"the volume should be fully allocated after the resize".
Since commit b0579ed9 we do not allocate from the existing
capacity, but from the existing allocation value.
However this value is a total of all the allocated bytes,
not an offset.
For a sparsely allocated file:
$ perl -e 'print "x"x8192;' > vol1
$ fallocate -p -o 0 -l 4096 vol1
$ virsh vol-info vol1 default
Capacity: 8.00 KiB
Allocation: 4.00 KiB
Treating allocation as an offset would result in an incompletely
allocated file:
$ virsh vol-resize vol1 --pool default 16384 --allocate
Capacity: 16.00 KiB
Allocation: 12.00 KiB
Call fallocate from zero on the whole requested capacity to fully
allocate the file. After that, the volume is fully allocated
after the resize:
$ virsh vol-resize vol1 --pool default 16384 --allocate
$ virsh vol-info vol1 default
Capacity: 16.00 KiB
Allocation: 16.00 KiB
libvirt library code README
===========================
The directory provides the bulk of the libvirt codebase. Everything
except for the libvirtd daemon and client tools. The build uses a
large number of libtool convenience libraries - one for each child
directory, and then links them together for the final libvirt.so,
although some bits get linked directly to libvirtd daemon instead.
The files directly in this directory are supporting the public API
entry points & data structures.
There are two core shared modules to be aware of:
* util/ - a collection of shared APIs that can be used by any
code. This directory is always in the include path
for all things built
* conf/ - APIs for parsing / manipulating all the official XML
files used by the public API. This directory is only
in the include path for driver implementation modules
* vmx/ - VMware VMX config handling (used by esx/ and vmware/)
Then there are the hypervisor implementations:
* bhyve - bhyve - The BSD Hypervisor
* esx/ - VMware ESX and GSX support using vSphere API over SOAP
* hyperv/ - Microsoft Hyper-V support using WinRM
* lxc/ - Linux Native Containers
* openvz/ - OpenVZ containers using cli tools
* phyp/ - IBM Power Hypervisor using CLI tools over SSH
* qemu/ - QEMU / KVM using qemu CLI/monitor
* remote/ - Generic libvirt native RPC client
* test/ - A "mock" driver for testing
* uml/ - User Mode Linux
* vbox/ - Virtual Box using native API
* vmware/ - VMware Workstation and Player using the vmrun tool
* xen/ - Xen using hypercalls, XenD SEXPR & XenStore
* xenapi/ - Xen using libxenserver
Finally some secondary drivers that are shared for several HVs.
Currently these are used by LXC, OpenVZ, QEMU, UML and Xen drivers.
The ESX, Hyper-V, Power Hypervisor, Remote, Test & VirtualBox drivers all
implement the secondary drivers directly
* cpu/ - CPU feature management
* interface/ - Host network interface management
* network/ - Virtual NAT networking
* nwfilter/ - Network traffic filtering rules
* node_device/ - Host device enumeration
* secret/ - Secret management
* security/ - Mandatory access control drivers
* storage/ - Storage management drivers
Since both the hypervisor and secondary drivers can be built as
dlopen()able modules, it is *FORBIDDEN* to have build dependencies
between these directories. Drivers are only allowed to depend on
the public API, and the internal APIs in the util/ and conf/
directories