[PATCH 1/3] qemu: implementation of transient option for qcow2 file

From: Masayoshi Mizuma <m.mizuma(a)jp.fujitsu.com&gt; Here is the implementation of transient option for qcow2 file. This gets available <transient/> directive in domain xml file like as: <disk type='file' device='disk'> <driver name='qemu' type='qcow2'/> <source file='/var/lib/libvirt/images/guest.qcow2'/> <target dev='vda' bus='virtio'/> <transient/> </disk> The internal procedure is as follows. When the qemu command line options are built, a new qcow2 image is created with backing qcow2 image by using qemu-img command. The backing image is the qcow2 file which is set as <source>. The filename of the new qcow2 image is original-source-file.TRANSIENT. The qemu-img will be: qemu-img create -f qcow2 -F qcow2 \ -b /var/lib/libvirt/images/guest.qcow2 \ /var/lib/libvirt/images/guest.qcow2.TRANSIENT Then, it switches the disk path, virStorageSourcePtr src->path, to the new qcow2 image. The new image and the backing image is handled and the blockdev option of qemu will be built like as: -blockdev '{"driver":"file","filename":"/var/lib/libvirt/images/guest.qcow2", "node-name":"libvirt-2-storage","auto-read-only":true,"discard":"unmap"}' \ -blockdev '{"node-name":"libvirt-2-format","read-only":true,"driver":"qcow2", "file":"libvirt-2-storage","backing":null}' \ -blockdev '{"driver":"file","filename":"/var/lib/libvirt/images/guest.qcow2.TRANSIENT", "node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}' \ -blockdev '{"node-name":"libvirt-1-format","read-only":false,"driver":"qcow2", "file":"libvirt-1-storage","backing":"libvirt-2-format"}' The new qcow2 image is removed when the Guest is shutdowned, Signed-off-by: Masayoshi Mizuma <m.mizuma(a)jp.fujitsu.com&gt; --- src/qemu/qemu_block.c | 71 ++++++++++++++++++++++++++++++++++++++++ src/qemu/qemu_block.h | 7 ++++ src/qemu/qemu_domain.c | 4 +++ src/qemu/qemu_process.c | 3 ++ src/qemu/qemu_validate.c | 2 +- 5 files changed, 86 insertions(+), 1 deletion(-) diff --git a/src/qemu/qemu_block.c b/src/qemu/qemu_block.c index 6f9c707..5eb0225 100644 --- a/src/qemu/qemu_block.c +++ b/src/qemu/qemu_block.c @@ -27,6 +27,7 @@ #include "viralloc.h" #include "virstring.h" #include "virlog.h" +#include "virqemu.h" #define VIR_FROM_THIS VIR_FROM_QEMU @@ -3438,3 +3439,73 @@ qemuBlockUpdateRelativeBacking(virDomainObjPtr vm, return 0; } + +int +qemuBlockCreateTransientDisk(virStorageSourcePtr src, + qemuDomainObjPrivatePtr priv) +{ + virBuffer buf = VIR_BUFFER_INITIALIZER; + virCommandPtr cmd = NULL; + g_autofree char *filename = NULL; + g_autofree char *dirname = NULL; + const char *qemuImgPath; + char *newpath; + int err = -1; + + if ((src->format != VIR_STORAGE_FILE_QCOW2)) { + virReportError(VIR_ERR_OPERATION_INVALID, + "%s", _("transient option supports qcow2")); + return -1; + } + + if (!(qemuImgPath = qemuFindQemuImgBinary(priv->driver))) + return -1; + + newpath = g_strdup_printf("%s.TRANSIENT", src->path); + + if (virFileExists(newpath)) { + virReportError(VIR_ERR_INVALID_ARG, + _(" '%s' is already exists. Please remove it."), newpath); + goto cleanup; + } + + if (!(cmd = virCommandNewArgList(qemuImgPath, + "create", + "-f", + "qcow2", + "-F", + "qcow2", + "-b", + NULL))) + goto cleanup; + + virQEMUBuildBufferEscapeComma(&buf, src->path); + virCommandAddArgBuffer(cmd, &buf); + + virQEMUBuildBufferEscapeComma(&buf, newpath); + virCommandAddArgBuffer(cmd, &buf); + + if (virCommandRun(cmd, NULL) < 0) + goto cleanup; + + VIR_DEBUG("Original disk: %s Transient disk: %s", src->path, newpath); + + g_free(src->path); + src->path = newpath; + + err = 0; + cleanup: + virBufferFreeAndReset(&buf); + virCommandFree(cmd); + if (err) + g_free(newpath); + + return err; +} + +void +qemuBlockRemoveTransientDisk(virStorageSourcePtr src) +{ + VIR_DEBUG("unlink transient disk: %s ", src->path); + unlink(src->path); +} diff --git a/src/qemu/qemu_block.h b/src/qemu/qemu_block.h index 2ad2ce1..60c6898 100644 --- a/src/qemu/qemu_block.h +++ b/src/qemu/qemu_block.h @@ -266,3 +266,10 @@ int qemuBlockUpdateRelativeBacking(virDomainObjPtr vm, virStorageSourcePtr src, virStorageSourcePtr topsrc); + +int +qemuBlockCreateTransientDisk(virStorageSourcePtr src, + qemuDomainObjPrivatePtr priv); + +void +qemuBlockRemoveTransientDisk(virStorageSourcePtr src); diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index d5e3d1a..9dbf73c 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -8301,6 +8301,10 @@ qemuDomainDetermineDiskChain(virQEMUDriverPtr driver, qemuDomainGetImageIds(cfg, vm, src, disksrc, &uid, &gid); + if (disk->transient) + if (qemuBlockCreateTransientDisk(src, vm->privateData) < 0) + return -1; + if (virStorageFileGetMetadata(src, uid, gid, report_broken) < 0) return -1; diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index 999e576..859ef82 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -7597,6 +7597,9 @@ void qemuProcessStop(virQEMUDriverPtr driver, } qemuBlockRemoveImageMetadata(driver, vm, disk->dst, disk->src); + + if (disk->transient) + qemuBlockRemoveTransientDisk(disk->src); } } diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c index 584d137..cdda6ac 100644 --- a/src/qemu/qemu_validate.c +++ b/src/qemu/qemu_validate.c @@ -2098,7 +2098,7 @@ qemuValidateDomainDeviceDefDiskFrontend(const virDomainDiskDef *disk, } } - if (disk->transient) { + if ((disk->transient) && (disk->src->format != VIR_STORAGE_FILE_QCOW2)) { virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", _("transient disks not supported yet")); return -1; -- 2.27.0