snapshots: Avoid term 'checkpoint' for full system snapshot

Upcoming patches plan to introduce virDomainCheckpointPtr as a new
object for use in incremental backups, along with documentation on
how incremental backups differ from snapshots.  But first, we need
to rename any existing mention of a 'system checkpoint' to instead
be a 'full system snapshot', so that we aren't overloading
the term checkpoint.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>

docs/formatsnapshot.html.in

@@ -33,7 +33,7 @@
         resume in a consistent state; but if the disks are modified
         externally in the meantime, this is likely to lead to data
         corruption.</dd>
-      <dt>system checkpoint</dt>
+      <dt>full system</dt>
       <dd>A combination of disk snapshots for all disks as well as VM
         memory state, which can be used to resume the guest from where it
         left off with symptoms similar to hibernation (that is, TCP
@@ -55,11 +55,12 @@
       as <code>virDomainSaveImageGetXMLDesc()</code> to work with
       those files.
     </p>
-    <p>System checkpoints are created
+    <p>Full system snapshots are created
-      by <code>virDomainSnapshotCreateXML()</code> with no flags, and
+      by <code>virDomainSnapshotCreateXML()</code> with no flags, while
       disk snapshots are created by the same function with
-      the <code>VIR_DOMAIN_SNAPSHOT_CREATE_DISK_ONLY</code> flag; in
+      the <code>VIR_DOMAIN_SNAPSHOT_CREATE_DISK_ONLY</code>
-      both cases, they are restored by
+      flag. Regardless of the flags provided, restoration of the
+      snapshot is handled by
       the <code>virDomainRevertToSnapshot()</code> function.  For
       these types of snapshots, libvirt tracks each snapshot as a
       separate <code>virDomainSnapshotPtr</code> object, and maintains
@@ -128,13 +129,10 @@
         what file name is created in an external snapshot.  On output,
         this is fully populated to show the state of each disk in the
         snapshot, including any properties that were generated by the
-        hypervisor defaults.  For system checkpoints, this field is
+        hypervisor defaults.  For full system snapshots, this field is
-        ignored on input and omitted on output (a system checkpoint
+        ignored on input and omitted on output (a full system snapshot
-        implies that all disks participate in the snapshot process,
+        implies that all disks participate in the snapshot process).
-        and since the current implementation only does internal system
+        This element has a list of <code>disk</code>
-        checkpoints, there are no extra details to add); a future
-        release may allow the use of <code>disks</code> with a system
-        checkpoint.  This element has a list of <code>disk</code>
         sub-elements, describing anywhere from zero to all of the
         disks associated with the domain.  <span class="since">Since
         0.9.5</span>
@@ -206,11 +204,12 @@
       </dd>
       <dt><code>state</code></dt>
       <dd>The state of the domain at the time this snapshot was taken.
-        If the snapshot was created as a system checkpoint, then this
+        If a full system snapshot was created, then this
-        is the state of the domain at that time; when the domain is
+        is the state of the domain at that time. When the domain is
         reverted to this snapshot, the domain's state will default to
-        whatever is in this field unless additional flags are passed
+        this state, unless overridden
-        to <code>virDomainRevertToSnapshot()</code>.  Additionally,
+        by <code>virDomainRevertToSnapshot()</code> flags to revert to
+        a running or paused state. Additionally,
         this field can be the value "disk-snapshot"
         (<span class="since">since 0.9.5</span>) when it represents
         only a disk snapshot (no VM memory state), and reverting to this

include/libvirt/libvirt-domain-snapshot.h

@@ -59,7 +59,7 @@ typedef enum {
     VIR_DOMAIN_SNAPSHOT_CREATE_HALT        = (1 << 3), /* Stop running guest
                                                           after snapshot */
     VIR_DOMAIN_SNAPSHOT_CREATE_DISK_ONLY   = (1 << 4), /* disk snapshot, not
-                                                          system checkpoint */
+                                                          full system */
     VIR_DOMAIN_SNAPSHOT_CREATE_REUSE_EXT   = (1 << 5), /* reuse any existing
                                                           external files */
     VIR_DOMAIN_SNAPSHOT_CREATE_QUIESCE     = (1 << 6), /* use guest agent to

src/conf/snapshot_conf.c

@@ -1296,8 +1296,8 @@ virDomainSnapshotRedefinePrep(virDomainPtr domain,
         if ((other->def->state == VIR_DOMAIN_DISK_SNAPSHOT) !=
             (def->state == VIR_DOMAIN_DISK_SNAPSHOT)) {
             virReportError(VIR_ERR_INVALID_ARG,
-                           _("cannot change between disk snapshot and "
+                           _("cannot change between disk only and "
-                             "system checkpoint in snapshot %s"),
+                             "full system in snapshot %s"),
                            def->name);
             goto cleanup;
         }

src/libvirt-domain-snapshot.c

@@ -105,8 +105,9 @@ virDomainSnapshotGetConnect(virDomainSnapshotPtr snapshot)
  * contained in xmlDesc.
  *
  * If @flags is 0, the domain can be active, in which case the
- * snapshot will be a system checkpoint (both disk state and runtime
+ * snapshot will be a full system snapshot (capturing both disk state,
- * VM state such as RAM contents), where reverting to the snapshot is
+ * and runtime VM state such as RAM contents), where reverting to the
+ * snapshot is
  * the same as resuming from hibernation (TCP connections may have
  * timed out, but everything else picks up where it left off); or
  * the domain can be inactive, in which case the snapshot includes
@@ -149,7 +150,7 @@ virDomainSnapshotGetConnect(virDomainSnapshotPtr snapshot)
  * is not paused while creating the snapshot. This increases the size
  * of the memory dump file, but reduces downtime of the guest while
  * taking the snapshot. Some hypervisors only support this flag during
- * external checkpoints.
+ * external snapshots.
  *
  * If @flags includes VIR_DOMAIN_SNAPSHOT_CREATE_DISK_ONLY, then the
  * snapshot will be limited to the disks described in @xmlDesc, and no

src/qemu/qemu_driver.c

@@ -2148,7 +2148,7 @@ qemuDomainReset(virDomainPtr dom, unsigned int flags)
 }
 
 
-/* Count how many snapshots in a set are external snapshots or checkpoints.  */
+/* Count how many snapshots in a set are external snapshots.  */
 static int
 qemuDomainSnapshotCountExternal(void *payload,
                                 const void *name ATTRIBUTE_UNUSED,
@@ -15093,7 +15093,7 @@ qemuDomainSnapshotPrepare(virDomainObjPtr vm,
     if ((def->memory == VIR_DOMAIN_SNAPSHOT_LOCATION_INTERNAL && !found_internal) ||
         (found_internal && forbid_internal)) {
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
-                       _("internal snapshots and checkpoints require all "
+                       _("internal and full system snapshots require all "
                          "disks to be selected for snapshot"));
         goto cleanup;
     }
@@ -15543,7 +15543,7 @@ qemuDomainSnapshotCreateActiveExternal(virQEMUDriverPtr driver,
     if (virDomainObjGetState(vm, NULL) == VIR_DOMAIN_PMSUSPENDED) {
         pmsuspended = true;
     } else if (virDomainObjGetState(vm, NULL) == VIR_DOMAIN_RUNNING) {
-        /* For external checkpoints (those with memory), the guest
+        /* For full system external snapshots (those with memory), the guest
          * must pause (either by libvirt up front, or by qemu after
          * _LIVE converges). */
         if (memory)
@@ -15771,7 +15771,7 @@ qemuDomainSnapshotCreateXML(virDomainPtr domain,
          redefine)) {
         virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
                        _("live snapshot creation is supported only "
-                         "with external checkpoints"));
+                         "during full system snapshots"));
         goto cleanup;
     }
 
@@ -15891,12 +15891,12 @@ qemuDomainSnapshotCreateXML(virDomainPtr domain,
     } else if (virDomainObjIsActive(vm)) {
         if (flags & VIR_DOMAIN_SNAPSHOT_CREATE_DISK_ONLY ||
             snap->def->memory == VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL) {
-            /* external checkpoint or disk snapshot */
+            /* external full system or disk snapshot */
             if (qemuDomainSnapshotCreateActiveExternal(driver,
                                                        vm, snap, flags) < 0)
                 goto endjob;
         } else {
-            /* internal checkpoint */
+            /* internal full system */
             if (qemuDomainSnapshotCreateActiveInternal(driver,
                                                        vm, snap, flags) < 0)
                 goto endjob;

tools/virsh-snapshot.c

@@ -1421,7 +1421,7 @@ static const vshCmdOptDef opts_snapshot_list[] = {
     },
     {.name = "active",
      .type = VSH_OT_BOOL,
-     .help = N_("filter by snapshots taken while active (system checkpoints)")
+     .help = N_("filter by snapshots taken while active (full system snapshots)")
     },
     {.name = "disk-only",
      .type = VSH_OT_BOOL,

tools/virsh.pod

@@ -4560,8 +4560,8 @@ If I<--halt> is specified, the domain will be left in an inactive state
 after the snapshot is created.
 
 If I<--disk-only> is specified, the snapshot will only include disk
-state rather than the usual system checkpoint with vm state.  Disk
+content rather than the usual full system snapshot with vm state.  Disk
-snapshots are faster than full system checkpoints, but reverting to a
+snapshots are captured faster than full system snapshots, but reverting to a
 disk snapshot may require fsck or journal replays, since it is like
 the disk state at the point when the power cord is abruptly pulled;
 and mixing I<--halt> and I<--disk-only> loses any data that was not
@@ -4600,10 +4600,10 @@ this.  If this flag is not specified, then some hypervisors may fail
 after partially performing the action, and B<dumpxml> must be used to
 see whether any partial changes occurred.
 
-If I<--live> is specified, libvirt takes the snapshot (checkpoint) while
+If I<--live> is specified, libvirt takes the snapshot while
 the guest is running. Both disk snapshot and domain memory snapshot are
 taken. This increases the size of the memory image of the external
-checkpoint. This is currently supported only for external checkpoints.
+snapshot. This is currently supported only for full system external snapshots.
 
 Existence of snapshot metadata will prevent attempts to B<undefine>
 a persistent domain.  However, for transient domains, snapshot
@@ -4623,7 +4623,7 @@ Otherwise, if I<--halt> is specified, the domain will be left in an
 inactive state after the snapshot is created, and if I<--disk-only>
 is specified, the snapshot will not include vm state.
 
-The I<--memspec> option can be used to control whether a checkpoint
+The I<--memspec> option can be used to control whether a full system snapshot
 is internal or external.  The I<--memspec> flag is mandatory, followed
 by a B<memspec> of the form B<[file=]name[,snapshot=type]>, where
 type can be B<no>, B<internal>, or B<external>.  To include a literal
@@ -4631,7 +4631,7 @@ comma in B<file=name>, escape it with a second comma. I<--memspec> cannot
 be used together with I<--disk-only>.
 
 The I<--diskspec> option can be used to control how I<--disk-only> and
-external checkpoints create external files.  This option can occur
+external full system snapshots create external files.  This option can occur
 multiple times, according to the number of <disk> elements in the domain
 xml.  Each <diskspec> is in the
 form B<disk[,snapshot=type][,driver=type][,file=name]>.  A I<diskspec>
@@ -4671,7 +4671,7 @@ see whether any partial changes occurred.
 
 If I<--live> is specified, libvirt takes the snapshot while the guest is
 running. This increases the size of the memory image of the external
-checkpoint. This is currently supported only for external checkpoints.
+snapshot. This is currently supported only for external full system snapshots.
 
 =item B<snapshot-current> I<domain> {[I<--name>] | [I<--security-info>]
 | [I<snapshotname>]}