[PATCH 19/24] checkpoint: Mention that VIR_DOMAIN_CHECKPOINT_XML_SIZE is expensive and stale

Data is valid only when queried as guest writes may increase the backup size. Signed-off-by: Peter Krempa <pkrempa(a)redhat.com&gt; --- docs/formatcheckpoint.rst | 4 ++++ src/libvirt-domain-checkpoint.c | 3 ++- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/docs/formatcheckpoint.rst b/docs/formatcheckpoint.rst index e45745390a..f159f2a7a3 100644 --- a/docs/formatcheckpoint.rst +++ b/docs/formatcheckpoint.rst @@ -86,6 +86,10 @@ The top-level ``domaincheckpoint`` element may contain the following elements: perform a dynamic query of the estimated size in bytes of the changes made since the checkpoint was created. + Note that updating the backup ``size`` may be expensive and + the actual required size may increase if the guest OS is actively + writing to the disk. + ``creationTime`` A readonly representation of the time this checkpoint was created. The time is specified in seconds since the Epoch, UTC (i.e. Unix time). diff --git a/src/libvirt-domain-checkpoint.c b/src/libvirt-domain-checkpoint.c index 50627c486c..8a7b55dcd2 100644 --- a/src/libvirt-domain-checkpoint.c +++ b/src/libvirt-domain-checkpoint.c @@ -191,7 +191,8 @@ virDomainCheckpointCreateXML(virDomainPtr domain, * VIR_DOMAIN_CHECKPOINT_XML_SIZE, each <disk> listing adds an additional * attribute that shows an estimate of the current size in bytes that * have been dirtied between the time the checkpoint was created and the - * current point in time. + * current point in time. Note that updating the size may be expensive and + * data will be inaccurate once guest OS writes to the disk. * * Returns a 0 terminated UTF-8 encoded XML instance or NULL in case * of error. The caller must free() the returned value. -- 2.26.2