From: Peter Krempa <pkrempa@redhat.com> In certain cases it's useful for the caller to be able to determine if given API supports some flags. To do this with 'virDomainBlockResize', if 'VIR_DOMAIN_BLOCK_RESIZE_PROBE_FLAGS' is specified, the API will return success right after flag verification, regardless of other input arguments and without modifying anything. Signed-off-by: Peter Krempa <pkrempa@redhat.com> --- include/libvirt/libvirt-domain.h | 9 +++++++++ src/libvirt-domain.c | 12 ++++++++++++ src/qemu/qemu_driver.c | 7 ++++++- src/vz/vz_driver.c | 7 ++++++- 4 files changed, 33 insertions(+), 2 deletions(-) diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-domain.h index 4a8e3114b3..113c7eefe6 100644 --- a/include/libvirt/libvirt-domain.h +++ b/include/libvirt/libvirt-domain.h @@ -2354,6 +2354,15 @@ typedef enum { /* Disallow shrinking (Since: 12.3.0) */ VIR_DOMAIN_BLOCK_RESIZE_EXTEND = 1 << 2, + + /* Ensures that the 'virDomainBlockResize' API returns success after + * checking support of 'flags' regardless of other arguments without + * actually modifying any aspect of the domain. + * + * Use of the flag thus allows probing for support of other flags of this + * API. (Since: 12.3.0) */ + VIR_DOMAIN_BLOCK_RESIZE_PROBE_FLAGS = 1 << 3, + } virDomainBlockResizeFlags; int virDomainBlockResize (virDomainPtr dom, diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c index db9eea5774..1b49d2f7e5 100644 --- a/src/libvirt-domain.c +++ b/src/libvirt-domain.c @@ -6469,6 +6469,18 @@ virDomainBlockPeek(virDomainPtr dom, * can be found by calling virDomainGetXMLDesc() and inspecting * elements within //domain/devices/disk. * + * If @flags contains VIR_DOMAIN_BLOCK_RESIZE_PROBE_FLAGS (since 12.3.0) the + * API will return success right after checking flags for support without + * modifying the disk in any way, thus allowing probing of flags with the + * following algorithm + * + * supp = virDomainBlockResize(dom, "", 0, VIR_DOMAIN_BLOCK_RESIZE_PROBE_FLAGS | VIR_DOMAIN_BLOCK_RESIZE_EXTEND); + * + * if (supp == 0) + * //flag supported + * else + * virResetLastError(); + * * Note that this call may fail if the underlying virtualization hypervisor * does not support it; this call requires privileged access to the * hypervisor. diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 551553df14..aa064ca7a9 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -9449,7 +9449,12 @@ qemuDomainBlockResize(virDomainPtr dom, virCheckFlags(VIR_DOMAIN_BLOCK_RESIZE_BYTES | VIR_DOMAIN_BLOCK_RESIZE_CAPACITY | - VIR_DOMAIN_BLOCK_RESIZE_EXTEND, -1); + VIR_DOMAIN_BLOCK_RESIZE_EXTEND | + VIR_DOMAIN_BLOCK_RESIZE_PROBE_FLAGS, -1); + + /* Assume success if flag probing is requested */ + if (flags & VIR_DOMAIN_BLOCK_RESIZE_PROBE_FLAGS) + return 0; /* We prefer operating on bytes. */ if ((flags & VIR_DOMAIN_BLOCK_RESIZE_BYTES) == 0) { diff --git a/src/vz/vz_driver.c b/src/vz/vz_driver.c index 2d8878fe7f..efb0144093 100644 --- a/src/vz/vz_driver.c +++ b/src/vz/vz_driver.c @@ -3901,7 +3901,12 @@ vzDomainBlockResize(virDomainPtr domain, int ret = -1; bool job = false; - virCheckFlags(VIR_DOMAIN_BLOCK_RESIZE_BYTES, -1); + virCheckFlags(VIR_DOMAIN_BLOCK_RESIZE_BYTES | + VIR_DOMAIN_BLOCK_RESIZE_PROBE_FLAGS, -1); + + /* Assume success if flag probing is requested */ + if (flags & VIR_DOMAIN_BLOCK_RESIZE_PROBE_FLAGS) + return 0; if (!(dom = vzDomObjFromDomain(domain))) goto cleanup; -- 2.53.0