July 2011 - Devel - libvirt List Archives

[libvirt] libvirt-0.9.3 and qemu-0.14.1
by Zdenek Styblik 28 Jul '11

28 Jul '11

Hello, I'm not sure if this has been reported or fixed, but ... ~~~ SNIP ~~~ 21:02:59.981: 13171: info : libvirt version: 0.9.3 21:02:59.981: 13171: error : virCommandWait:1957 : internal error Child process (LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/sbin:/usr/sbin:/bin:/usr/bin HOME=/root USER=root LOGNAME=root /usr/bin/qemu-kvm -help) status unexpected: exit status 1 21:02:59.986: 13171: error : virCommandWait:1957 : internal error Child process (LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/sbin:/usr/sbin:/bin:/usr/bin HOME=/root USER=root LOGNAME=root /usr/bin/qemu-kvm -help) status unexpected: exit status 1 21:02:59.988: 13171: error : virDomainDefParseXML:6069 : unknown OS type hvm ~~~ SNIP ~~~ qemu-0.14.1 and libvirt-0.9.3 What am I missing here? Thanks, Z. -- Zdenek Styblik email: stybla(a)turnovfree.net jabber: stybla(a)jabber.turnovfree.net

1 1

[libvirt] [PATCH] freebsd: Fix build problem due to picking up the wrong libvirt.h
by Matthias Bolte 28 Jul '11

28 Jul '11

AM_GNU_GETTEXT calls AM_ICONV_LINK. AM_ICONV_LINK saves and alters CPPFLAGS, but doesn't restore it when it finds libiconv. This results in /usr/local/include ending up in the gcc command line before the include path for the local include directory. This makes gcc pick a previous installed libvirt.h instead of the correct one from the source tree. Workaround this problem by saving and restoring CPPFLAGS around the AM_GNU_GETTEXT call. --- configure.ac | 8 ++++++++ 1 files changed, 8 insertions(+), 0 deletions(-) diff --git a/configure.ac b/configure.ac index b2ba930..8f46dbd 100644 --- a/configure.ac +++ b/configure.ac @@ -2011,8 +2011,16 @@ dnl Enable building libvirtd? AM_CONDITIONAL([WITH_LIBVIRTD],[test "x$with_libvirtd" = "xyes"]) dnl Check for gettext - don't go any newer than what RHEL 5 supports +dnl +dnl save and restore CPPFLAGS around gettext check as the internal iconv +dnl check might leave -I/usr/local/include in CPPFLAGS on FreeBSD resulting +dnl in the build picking up previously installed libvirt/libvirt.h instead +dnl of the correct one from the soucre tree + +save_CPPFLAGS="$CPPFLAGS" AM_GNU_GETTEXT_VERSION([0.17]) AM_GNU_GETTEXT([external]) +CPPFLAGS="$save_CPPFLAGS" ALL_LINGUAS=`cd "$srcdir/po" > /dev/null && ls *.po | sed 's+\.po$++'` -- 1.7.0.4

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[libvirt] [PATCH v4] virsh: avoid missing zero value judgement in cmdBlkiotune
by ajia＠redhat.com 28 Jul '11

28 Jul '11

* tools/virsh.c: fix missing zero value judgement in cmdBlkiotune and correct vshError information. when weight is equal to 0, the cmdBlkiotune will not raise any error information when judge weight value first time, and execute else branch to judge weight value again, strncpy(temp->field, VIR_DOMAIN_BLKIO_WEIGHT, sizeof(temp->field)) will be not executed for ever. However, if and only if param->field is equal to VIR_DOMAIN_BLKIO_WEIGHT, underlying qemuDomainSetBlkioParameters function will check whether weight value is in range [100, 1000]. * how to reproduce? % virsh blkiotune ${guestname} --weight 0 Signed-off-by: Alex Jia <ajia(a)redhat.com> --- tools/virsh.c | 9 +++++---- 1 files changed, 5 insertions(+), 4 deletions(-) diff --git a/tools/virsh.c b/tools/virsh.c index 8bd22dc..feb45de 100644 --- a/tools/virsh.c +++ b/tools/virsh.c @@ -4004,6 +4004,7 @@ cmdBlkiotune(vshControl * ctl, const vshCmd * cmd) virDomainPtr dom; int weight = 0; int nparams = 0; + int rv = 0; unsigned int i = 0; virTypedParameterPtr params = NULL, temp = NULL; bool ret = false; @@ -4031,15 +4032,15 @@ cmdBlkiotune(vshControl * ctl, const vshCmd * cmd) if (!(dom = vshCommandOptDomain(ctl, cmd, NULL))) return false; - if (vshCommandOptInt(cmd, "weight", &weight) < 0) { + if ((rv = vshCommandOptInt(cmd, "weight", &weight)) < 0) { vshError(ctl, "%s", - _("Unable to parse integer parameter")); + _("Unable to parse non-integer parameter")); goto cleanup; } - if (weight) { + if (rv > 0) { nparams++; - if (weight < 0) { + if (weight <= 0) { vshError(ctl, _("Invalid value of %d for I/O weight"), weight); goto cleanup; } -- 1.7.1

4 4

[libvirt] [PATCH] qemu: fix nested job with driver lock held
by Eric Blake 28 Jul '11

28 Jul '11

qemuMigrationUpdateJobStatus (called in a loop by migration and save tasks) uses qemuDomainObjEnterMonitorWithDriver; however, that function ended up starting a nested job without releasing the driver. Since no one else is making nested calls, we can inline the internal functions to properly track driver_locked. * src/qemu/qemu_domain.h (qemuDomainObjBeginNestedJob) (qemuDomainObjBeginNestedJobWithDriver) (qemuDomainObjEndNestedJob): Drop unused prototypes. * src/qemu/qemu_domain.c (qemuDomainObjEnterMonitorInternal): Reflect driver lock to nested job. (qemuDomainObjBeginNestedJob) (qemuDomainObjBeginNestedJobWithDriver) (qemuDomainObjEndNestedJob): Drop unused functions. --- This does not solve the crash in 'virsh managedsave', but hopefully will make analysis easier in finding where we are freeing the monitor too early when probing to see if outgoing migration is completed. src/qemu/qemu_domain.c | 59 +++++++++++------------------------------------ src/qemu/qemu_domain.h | 9 ------- 2 files changed, 14 insertions(+), 54 deletions(-) diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index fe88ce3..2eaaf3a 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -832,31 +832,6 @@ int qemuDomainObjBeginAsyncJobWithDriver(struct qemud_driver *driver, } /* - * Use this to protect monitor sections within active async job. - * - * The caller must call qemuDomainObjBeginAsyncJob{,WithDriver} before it can - * use this method. Never use this method if you only own non-async job, use - * qemuDomainObjBeginJob{,WithDriver} instead. - */ -int -qemuDomainObjBeginNestedJob(struct qemud_driver *driver, - virDomainObjPtr obj) -{ - return qemuDomainObjBeginJobInternal(driver, false, obj, - QEMU_JOB_ASYNC_NESTED, - QEMU_ASYNC_JOB_NONE); -} - -int -qemuDomainObjBeginNestedJobWithDriver(struct qemud_driver *driver, - virDomainObjPtr obj) -{ - return qemuDomainObjBeginJobInternal(driver, true, obj, - QEMU_JOB_ASYNC_NESTED, - QEMU_ASYNC_JOB_NONE); -} - -/* * obj must be locked before calling, qemud_driver does not matter * * To be called after completing the work associated with the @@ -888,21 +863,6 @@ qemuDomainObjEndAsyncJob(struct qemud_driver *driver, virDomainObjPtr obj) return virDomainObjUnref(obj); } -void -qemuDomainObjEndNestedJob(struct qemud_driver *driver, virDomainObjPtr obj) -{ - qemuDomainObjPrivatePtr priv = obj->privateData; - - qemuDomainObjResetJob(priv); - qemuDomainObjSaveJob(driver, obj); - virCondSignal(&priv->job.cond); - - /* safe to ignore since the surrounding async job increased the reference - * counter as well */ - ignore_value(virDomainObjUnref(obj)); -} - - static int ATTRIBUTE_NONNULL(1) qemuDomainObjEnterMonitorInternal(struct qemud_driver *driver, bool driver_locked, @@ -911,7 +871,9 @@ qemuDomainObjEnterMonitorInternal(struct qemud_driver *driver, qemuDomainObjPrivatePtr priv = obj->privateData; if (priv->job.active == QEMU_JOB_NONE && priv->job.asyncJob) { - if (qemuDomainObjBeginNestedJob(driver, obj) < 0) + if (qemuDomainObjBeginJobInternal(driver, driver_locked, obj, + QEMU_JOB_ASYNC_NESTED, + QEMU_ASYNC_JOB_NONE) < 0) return -1; if (!virDomainObjIsActive(obj)) { qemuReportError(VIR_ERR_OPERATION_FAILED, "%s", @@ -952,8 +914,15 @@ qemuDomainObjExitMonitorInternal(struct qemud_driver *driver, priv->mon = NULL; } - if (priv->job.active == QEMU_JOB_ASYNC_NESTED) - qemuDomainObjEndNestedJob(driver, obj); + if (priv->job.active == QEMU_JOB_ASYNC_NESTED) { + qemuDomainObjResetJob(priv); + qemuDomainObjSaveJob(driver, obj); + virCondSignal(&priv->job.cond); + + /* safe to ignore since the surrounding async job increased + * the reference counter as well */ + ignore_value(virDomainObjUnref(obj)); + } } /* @@ -962,7 +931,7 @@ qemuDomainObjExitMonitorInternal(struct qemud_driver *driver, * To be called immediately before any QEMU monitor API call * Must have already either called qemuDomainObjBeginJob() and checked * that the VM is still active or called qemuDomainObjBeginAsyncJob, in which - * case this will call qemuDomainObjBeginNestedJob. + * case this will start a nested job. * * To be followed with qemuDomainObjExitMonitor() once complete */ @@ -988,7 +957,7 @@ void qemuDomainObjExitMonitor(struct qemud_driver *driver, * To be called immediately before any QEMU monitor API call * Must have already either called qemuDomainObjBeginJobWithDriver() and * checked that the VM is still active or called qemuDomainObjBeginAsyncJob, - * in which case this will call qemuDomainObjBeginNestedJobWithDriver. + * in which case this will start a nested job. * * To be followed with qemuDomainObjExitMonitorWithDriver() once complete */ diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h index 679259f..8bff8b0 100644 --- a/src/qemu/qemu_domain.h +++ b/src/qemu/qemu_domain.h @@ -143,9 +143,6 @@ int qemuDomainObjBeginAsyncJob(struct qemud_driver *driver, virDomainObjPtr obj, enum qemuDomainAsyncJob asyncJob) ATTRIBUTE_RETURN_CHECK; -int qemuDomainObjBeginNestedJob(struct qemud_driver *driver, - virDomainObjPtr obj) - ATTRIBUTE_RETURN_CHECK; int qemuDomainObjBeginJobWithDriver(struct qemud_driver *driver, virDomainObjPtr obj, enum qemuDomainJob job) @@ -154,9 +151,6 @@ int qemuDomainObjBeginAsyncJobWithDriver(struct qemud_driver *driver, virDomainObjPtr obj, enum qemuDomainAsyncJob asyncJob) ATTRIBUTE_RETURN_CHECK; -int qemuDomainObjBeginNestedJobWithDriver(struct qemud_driver *driver, - virDomainObjPtr obj) - ATTRIBUTE_RETURN_CHECK; int qemuDomainObjEndJob(struct qemud_driver *driver, virDomainObjPtr obj) @@ -164,9 +158,6 @@ int qemuDomainObjEndJob(struct qemud_driver *driver, int qemuDomainObjEndAsyncJob(struct qemud_driver *driver, virDomainObjPtr obj) ATTRIBUTE_RETURN_CHECK; -void qemuDomainObjEndNestedJob(struct qemud_driver *driver, - virDomainObjPtr obj); - void qemuDomainObjSetJobPhase(struct qemud_driver *driver, virDomainObjPtr obj, int phase); -- 1.7.4.4

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[libvirt] [PATCH] build: avoid type-punning compiler warning
by Eric Blake 28 Jul '11

28 Jul '11

On RHEL 5, with gcc 4.1.2: rpc/virnetsaslcontext.c: In function 'virNetSASLSessionUpdateBufSize': rpc/virnetsaslcontext.c:396: warning: dereferncing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing] * src/rpc/virnetsaslcontext.c (virNetSASLSessionUpdateBufSize): Use a union to work around gcc warning. --- src/rpc/virnetsaslcontext.c | 11 +++++++---- 1 files changed, 7 insertions(+), 4 deletions(-) diff --git a/src/rpc/virnetsaslcontext.c b/src/rpc/virnetsaslcontext.c index 71796b9..a0752dd 100644 --- a/src/rpc/virnetsaslcontext.c +++ b/src/rpc/virnetsaslcontext.c @@ -390,10 +390,13 @@ cleanup: static int virNetSASLSessionUpdateBufSize(virNetSASLSessionPtr sasl) { - unsigned *maxbufsize; + union { + unsigned *maxbufsize; + const void *ptr; + } u; int err; - err = sasl_getprop(sasl->conn, SASL_MAXOUTBUF, (const void **)&maxbufsize); + err = sasl_getprop(sasl->conn, SASL_MAXOUTBUF, &u.ptr); if (err != SASL_OK) { virNetError(VIR_ERR_INTERNAL_ERROR, _("cannot get security props %d (%s)"), @@ -402,8 +405,8 @@ static int virNetSASLSessionUpdateBufSize(virNetSASLSessionPtr sasl) } VIR_DEBUG("Negotiated bufsize is %u vs requested size %zu", - *maxbufsize, sasl->maxbufsize); - sasl->maxbufsize = *maxbufsize; + *u.maxbufsize, sasl->maxbufsize); + sasl->maxbufsize = *u.maxbufsize; return 0; } -- 1.7.4.4

2 2

[libvirt] [PATCH] qemu: Fix memory leak on metadata fetching
by Michal Privoznik 28 Jul '11

28 Jul '11

As written in virStorageFileGetMetadataFromFD decription, caller must free metadata after use. Qemu driver miss this and therefore leak metadata which can grow to huge mem leak if somebody query for blockInfo a lot. --- src/qemu/qemu_driver.c | 14 ++++++++++---- 1 files changed, 10 insertions(+), 4 deletions(-) diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 0f91910..d45c7c5 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -6949,7 +6949,7 @@ static int qemuDomainGetBlockInfo(virDomainPtr dom, int ret = -1; int fd = -1; off_t end; - virStorageFileMetadata meta; + virStorageFileMetadata *meta = NULL; virDomainDiskDefPtr disk = NULL; struct stat sb; int i; @@ -7017,9 +7017,14 @@ static int qemuDomainGetBlockInfo(virDomainPtr dom, } } + if (VIR_ALLOC(meta) < 0) { + virReportOOMError(); + goto cleanup; + } + if (virStorageFileGetMetadataFromFD(path, fd, format, - &meta) < 0) + meta) < 0) goto cleanup; /* Get info for normal formats */ @@ -7056,8 +7061,8 @@ static int qemuDomainGetBlockInfo(virDomainPtr dom, /* If the file we probed has a capacity set, then override * what we calculated from file/block extents */ - if (meta.capacity) - info->capacity = meta.capacity; + if (meta->capacity) + info->capacity = meta->capacity; /* Set default value .. */ info->allocation = info->physical; @@ -7091,6 +7096,7 @@ static int qemuDomainGetBlockInfo(virDomainPtr dom, } cleanup: + virStorageFileFreeMetadata(meta); VIR_FORCE_CLOSE(fd); if (vm) virDomainObjUnlock(vm); -- 1.7.5.rc3

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Re: [libvirt] PCI devices passthough to LXC containers using libvirt
by Devendra K. Modium 28 Jul '11

28 Jul '11

Hi Thanks for the reply. I think the links that you provided show how to deal with pci devices in case the hypervisor is kvm. Please correct me if I am wrong. But I am using LXC containers.I have skimmed through the libvirt lxc driver code and found no functionality of allowing specified devices into a container exists other than currently where only hard coded devices are allowed which can be seen in the file lxc_controller.c struct cgroup_device_policy devices[] = { {'c', LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_NULL}, {'c', LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_ZERO}, {'c', LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_FULL}, {'c', LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_RANDOM}, {'c', LXC_DEV_MAJ_MEMORY, LXC_DEV_MIN_URANDOM}, {'c', LXC_DEV_MAJ_TTY, LXC_DEV_MIN_TTY}, {'c', LXC_DEV_MAJ_TTY, LXC_DEV_MIN_PTMX}, {0, 0, 0}}; Please confirm this or let me know if there is any other interface libvirt_lxc provides to allow specific pci/other devices into container. Thanks in advance Regards Devendra ----- Original Message ----- From: "Alex Jia" <ajia(a)redhat.com> To: "Devendra K. Modium" <dmodium(a)isi.edu> Sent: Thursday, July 28, 2011 3:22:36 AM Subject: Re: [libvirt] PCI devices passthough to LXC containers using libvirt On 07/28/2011 05:13 AM, Devendra K. Modium wrote: > Hi All > > Please let me know if anyone have given access to > PCI devices for a LXC container. > > I have tried getting the xml from > "virsh nodedev-dumpxml pci_device" and > added to the libvirt xml file as shown below > > <device> > <name>pci_0000_03_00_0</name> > <parent>pci_0000_00_03_0</parent> > <driver> > <name>nvidia</name> > </driver> > <capability type='pci'> > <domain>0</domain> > <bus>3</bus> > <slot>0</slot> > <function>0</function> > <product id='0x06fd' /> > <vendor id='0x10de'>nVidia Corporation</vendor> > </capability> > </device> You shouldn't directly add the above xml to guest xml configuration, here is a usage, it should be helpful for you: http://libvirt.org/formatdomain.html#elementsUSB http://fedoraproject.org/wiki/Category:Virtualization_KVM_PCI_Device_Assign… Good Luck! Alex > > But it didn't work. I see the logs and it says > couldn't get physical and virtual functions of these devices with error > > get_physical_function_linux:323 : Attempting to get SR IOV physical function for device with sysfs path '/sys/devices/pci0000:00/0000:00:00.0' > 16:48:34.033: 13802: debug : get_sriov_function:270 : Attempting to resolve device path from device link '/sys/devices/pci0000:00/0000:00:00.0/physfn' > 16:48:34.033: 13802: debug : get_sriov_function:274 : SR IOV function link '/sys/devices/pci0000:00/0000:00:00.0/physfn' does not exist > 16:48:34.033: 13802: debug : get_virtual_functions_linux:348 : Attempting to get SR IOV virtual functions for devicewith sysfs path '/sys/devices/pci0000:00/0000:00:00.0' > > > If anyone got some guidelines how to debug, please let me know. > > > Thanks in advance > > Regards > Devendra > > > > > > > > -- > libvir-list mailing list > libvir-list(a)redhat.com > https://www.redhat.com/mailman/listinfo/libvir-list

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[libvirt] [PATCH v3] virsh: avoid missing zero value judgement in cmdBlkiotune
by ajia＠redhat.com 28 Jul '11

28 Jul '11

* tools/virsh.c: avoid missing zero value judgement in cmdBlkiotune, when weight is equal to 0, the cmdBlkiotune will not raise any error information when judge weight value first time, and execute else branch to judge weight value again, strncpy(temp->field, VIR_DOMAIN_BLKIO_WEIGHT, sizeof(temp->field)) will be not executed for ever. However, if and only if param->field is equal to VIR_DOMAIN_BLKIO_WEIGHT, underlying qemuDomainSetBlkioParameters function will check whether weight value is in range [100, 1000]. * how to reproduce? % virsh blkiotune ${guestname} --weight 0 Signed-off-by: Alex Jia <ajia(a)redhat.com> --- tools/virsh.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-) diff --git a/tools/virsh.c b/tools/virsh.c index 8bd22dc..f24050d 100644 --- a/tools/virsh.c +++ b/tools/virsh.c @@ -4037,12 +4037,12 @@ cmdBlkiotune(vshControl * ctl, const vshCmd * cmd) goto cleanup; } - if (weight) { - nparams++; - if (weight < 0) { + if (vshCommandOptInt(cmd, "weight", &weight) > 0) { + if (weight <= 0) { vshError(ctl, _("Invalid value of %d for I/O weight"), weight); goto cleanup; } + nparams++; } if (nparams == 0) { -- 1.7.1

4 3

[libvirt] [PATCH v2] virsh: avoid missing zero value judgement in cmdBlkiotune
by ajia＠redhat.com 28 Jul '11

28 Jul '11

* tools/virsh.c: avoid missing zero value judgement in cmdBlkiotune, when weight is equal to 0, the cmdBlkiotune will not raise any error information when judge weight value first time, and execute else branch to judge weight value again, strncpy(temp->field, VIR_DOMAIN_BLKIO_WEIGHT, sizeof(temp->field)) will be not executed for ever. However, if and only if param->field is equal to VIR_DOMAIN_BLKIO_WEIGHT, underlying qemuDomainSetBlkioParameters function will check whether weight value is in range [100, 1000]. * how to reproduce? % virsh blkiotune ${guestname} --weight 0 Signed-off-by: Alex Jia <ajia(a)redhat.com> --- tools/virsh.c | 11 +++++------ 1 files changed, 5 insertions(+), 6 deletions(-) diff --git a/tools/virsh.c b/tools/virsh.c index 8bd22dc..512f2c6 100644 --- a/tools/virsh.c +++ b/tools/virsh.c @@ -4037,14 +4037,13 @@ cmdBlkiotune(vshControl * ctl, const vshCmd * cmd) goto cleanup; } - if (weight) { - nparams++; - if (weight < 0) { - vshError(ctl, _("Invalid value of %d for I/O weight"), weight); - goto cleanup; - } + if (weight <= 0) { + vshError(ctl, _("Invalid value of %d for I/O weight"), weight); + goto cleanup; } + nparams++; + if (nparams == 0) { /* get the number of blkio parameters */ if (virDomainGetBlkioParameters(dom, NULL, &nparams, flags) != 0) { -- 1.7.1

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[libvirt] RFC: API additions for enhanced snapshot support
by Eric Blake 28 Jul '11

28 Jul '11

Right now, libvirt has a snapshot API via virDomainSnapshotCreateXML, but for qemu domains, it only works if all the guest disk images are qcow2, and qemu rather than libvirt does all the work. However, it has a couple of drawbacks: it is inherently tied to domains (there is no way to manage snapshots of storage volumes not tied to a domain, even though libvirt does that for qcow2 images associated with offline qemu domains by using the qemu-img application). And it necessarily operates on all of the images associated with a domain in parallel - if any disk image is not qcow2, the snapshot fails, and there is no way to select a subset of disks to save. However, it works on both active (disk and memory state) and inactive domains (just disk state). Upstream qemu is developing a 'live snapshot' feature, which allows the creation of a snapshot without the current downtime of several seconds required by the current 'savevm' monitor command, as well as means for controlling applications (libvirt) to request that qemu pause I/O to a particular disk, then externally perform a snapshot, then tell qemu to resume I/O (perhaps on a different file name or fd from the host, but with no change to the contents seen by the guest). Eventually, these changes will make it possible for libvirt to create fast snapshots of LVM partitions or btrfs files for guest disk images, as well as to select which disks are saved in a snapshot (that is, save a crash-consistent state of a subset of disks, without the corresponding RAM state, rather than making a full system restore point); the latter would work best with guest cooperation to quiesce disks before qemu pauses I/O to that disk, but that is an orthogonal enhancement. However, my first goal with API enhancements is to merely prove that libvirt can manage a live snapshot by using qemu-img on a qcow2 image rather than the current 'savevm' approach of qemu doing all the work. Additionally, libvirt provides the virDomainSave command, which saves just the state of the domain's memory, and stops the guest. A crude libvirt-only snapshot could thus already be done by using virDomainSave, then externally doing a snapshot of all disk images associated with the domain by using virStorageVol APIs, except that such APIs don't yet exist. Additionally, virDomainSave has no flags argument, so there is no way to request that the guest be resumed after the snapshot completes. Right now, I'm proposing the addition of virDomainSaveFlags, along with a series of virStorageVolSnapshot* APIs that mirror the virDomainSnapshot* APIs. This would mean adding: /* Opaque type to manage a snapshot of a single storage volume. */ typedef virStorageVolSnapshotPtr; /* Create a snapshot of a storage volume. XML is optional, if non-NULL, it would be a new top-level element <volsnapshot> which is similar to the top-level <domainsnapshot> for virDomainSnapshotCreateXML, to specify name and description. Flags is 0 for now. */ virStorageVolSnapshotPtr virDomainSnapshotCreateXML(virStorageVolPtr vol, const char *xml, unsigned int flags); [For qcow2, this would be implemented with 'qemu-img snapshot -c', similar to what virDomainSnapshotXML already does on inactive domains. Later, we can add LVM and btrfs support, or even allow full file copies of any file type. Also in the future, we could enhance XML to take a new element that describes a relationship between the name of the original and of the snapshot, in the case where a new filename has to be created to complete the snapshot process.] /* Probe if vol has snapshots. 1 if true, 0 if false, -1 on error. Flags is 0 for now. */ int virStorageVolHasCurrentSnapshot(virStorageVolPtr vol, unsigned int flags); [For qcow2 images, snapshots can be contained within the same file and managed with qemu-img -l, but for other formats, this may mean that libvirt has to start managing externally saved data associated with the storage pool that associates snapshots with filenames. In fact, even for qcow2 it might be useful to support creation of new files backed by the previous snapshot rather than cramming multiple snapshots in one file, so we may have a use for flags to filter out the presence of single-file vs. multiple-file snapshot setups.] /* Revert a volume back to the state of a snapshot, returning 0 on success. Flags is 0 for now. */ int virStorageVolRevertToSnapsot(virStorageVolSnapshotPtr snapshot, unsigned int flags); [For qcow2, this would involve qemu-img snapshot -a. Here, a useful flag might be whether to delete any changes made after the point of the snapshot; virDomainRevertToSnapshot should probably honor the same type of flag.] /* Return the most recent snapshot of a volume, if one exists, or NULL on failure. Flags is 0 for now. */ virStorageVolSnapshotPtr virStorageVolSnapshotCurrent(virStorageVolPtr vol, unsigned int flags); /* Delete the storage associated with a snapshot (although the opaque snapshot object must still be independently freed). If flags is 0, any child snapshots based off of this one are rebased onto the parent; if flags is VIR_STORAGE_VOL_SNAPSHOT_DELETE_CHILDREN , then any child snapshots based off of this one are also deleted. */ int virStorageVolSnapshotDelete(virStorageVolSnapshotPtr snapshot, unsigned int flags); [For qcow2, this would involve qemu-img snapshot -d. For multiple-file snapshots, this would also involve qemu-img commit.] /* Free the object returned by virStorageVolSnapshot{Current,CreateXML,LookupByName}. The storage snapshot associated with this object still exists, if it has not been deleted by virStorageVolSnapshotDelete. */ int virStorageVolSnapshotFree(virStorageVolSnapshotPtr snapshot); /* Return the <volsnapshot> XML details about this snapshot object. Flags is 0 for now. */ int virStorageVolSnapshotGetXMLDesc(virStorageVolSnapshotPtr snapshot, unsigned int flags); /* Return the names of all snapshots associated with this volume, using len from virStorageVolSnapshotLen. Flags is 0 for now. */ int virStorageVolSnapshotListNames(virStorageVolPtr vol, char **names, int nameslen, unsigned int flags); [For qcow2, this involves qemu-img -l. Additionally, if virStorageVolHasCurrentSnapshot learns to filter on in-file vs. multi-file snapshots, then the same flags would apply here.] /* Get the opaque object tied to a snapshot name. Flags is 0 for now. */ virStorageVolSnapshotPtr virStorageVolSnapshotLookupByName(virStorageVolPtr vol, const char *name, unsigned int flags); /* Determine how many snapshots are tied to a volume, or -1 on error. Flags is 0 for now. */ int virStorageVolSnapshotNum(virStorageVolPtr vol, unsigned int flags); [Same flags as for virStorageVolSnapshotListNames.] /* Save a domain into the file 'to' with additional actions. If flags is 0, then xml is ignored, and this is like virDomainSave. If flags includes VIR_DOMAIN_SAVE_DISKS, then all of the associated disk images are also snapshotted, as if by virStorageVolSnapshotCreateXML; the xml argument is optional, but if present, it should be a <domainsnapshot> element with <disk> sub-elements for directions on each disk that needs a non-empty xml argument for proper volume snapshot creation. If flags includes VIR_DOMAIN_SAVE_RESUME, then the guest is resumed after the offline snapshot is complete (note that VIR_DOMAIN_SAVE_RESUME without VIR_DOMAIN_SAVE_DISKS makes little sense, as a saved state file is rendered useless if the disk images are modified before it is resumed). If flags includes VIR_DOMAIN_SAVE_QUIESCE, this requests that a guest agent quiesce disk state before the saved state file is created. */ int virDomainSaveFlags(virDomainPtr domain, const char *to, const char *xml, unsigned int flags); Also, the existing virDomainSnapshotCreateXML can be made more powerful by adding new flags and enhancing the existing XML for <domainsnapshot>. When flags is 0, the current behavior of saving memory state alongside all disks (for running domains, via savevm) or just snapshotting all disks with default settings (for offline domains, via qemu-img) is kept. If flags includes VIR_DOMAIN_SNAPSHOT_LIVE, then the guest must be running, and the new monitor commands for live snapshots are used. If flags includes VIR_DOMAIN_SNAPSHOT_DISKS_ONLY, then only the disks are snapshotted (on a running guest, this generally means they will only be crash-consistent, and will need an fsck before that disk state can be remounted), but it will shave off time by not saving memory. If flags includes VIR_DOMAIN_SNAPSHOT_QUIESCE, then this will additionally request that a guest agent quiesce disk state before the live snapshot is taken (increasing the likelihood of a stable disk, rather than a crash-consistent disk; but it requires cooperation from the guest so it is no more reliable than memballoon changes). As for the XML changes, it makes sense to snapshot just a subset of disks when you only care about crash-consistent state or if you can rely on a guest agent to quiesce the subset of disk(s) you care about, so the existing <domainsnapshot> element needs a new optional subelement to control which disks are snapshotted; additionally, this subelement will be useful for disk image formats that require additional complexity (such as a secondary file name, rather than the inline snapshot feature of qcow2). I'm envisioning something like the following: <domainsnapshot> <name>whatever</name> <disk name='/path/to/image1' snapshot='no'/> <disk name='/path/to/image2'> <volsnapshot>...</volsnapshot> </disk> </domainsnapshot> where there can be up to as many <disk> elements as there are disk <devices> in the domain xml; any domain disk not listed is given default treatment. The name attribute of <disk> is mandatory, in order to match this disk element to one of the domain disks. The snapshot='yes|no' attribute is optional, defaulting to yes, in order to skip a particular disk. The <volsnapshot> subelement is optional, but if present, it would be the same XML as is provided to the virStorageVolSnapshotCreateXML. [And since my first phase of implementation will be focused on inline qcow2 snapshots, I don't yet know what that XML will need to contain for any other type of snapshots, such as mapping out how the snapshot backing file will be named in relation to the possibly new live file.] Any feedback on this approach? Any other APIs that would be useful to add? I'd like to get all the new APIs in place for 0.9.3 with minimal qcow2 functionality, then use the time before 0.9.4 to further enhance the APIs to cover more snapshot cases but without having to add any new APIs. -- Eric Blake eblake(a)redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org

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