[libvirt] [PATCHv4 25/51] snapshot: teach virsh about new undefine flags
Eric Blake
eblake at redhat.com
Fri Sep 2 04:25:02 UTC 2011
Similar to 'undefine --managed-save' (commit 83e849c1), we must
assume that the old API is unsafe; however, we cannot emulate
metadata-only deletion on older servers. Additionally, we have
the wrinkle that while virDomainUndefineFlags and managed save
cleanup were introduced in 0.9.4, it wasn't until 0.9.5 that
snapshots block undefine of a domain. Do the best we can given
the server we are talking to.
* tools/virsh.c (cmdUndefine): Add --snapshots-metadata flag.
* tools/virsh.pod (undefine, destroy, shutdown): Document effect
of snapshots.
---
tools/virsh.c | 156 ++++++++++++++++++++++++++++++++++++++++--------------
tools/virsh.pod | 25 ++++++++-
2 files changed, 138 insertions(+), 43 deletions(-)
diff --git a/tools/virsh.c b/tools/virsh.c
index e6a053b..2fa25ea 100644
--- a/tools/virsh.c
+++ b/tools/virsh.c
@@ -1434,6 +1434,8 @@ static const vshCmdInfo info_undefine[] = {
static const vshCmdOptDef opts_undefine[] = {
{"domain", VSH_OT_DATA, VSH_OFLAG_REQ, N_("domain name or uuid")},
{"managed-save", VSH_OT_BOOL, 0, N_("remove domain managed state file")},
+ {"snapshots-metadata", VSH_OT_BOOL, 0,
+ N_("remove all domain snapshot metadata, if inactive")},
{NULL, 0, 0, NULL}
};
@@ -1441,18 +1443,31 @@ static bool
cmdUndefine(vshControl *ctl, const vshCmd *cmd)
{
virDomainPtr dom;
- bool ret = true;
+ bool ret = false;
const char *name = NULL;
+ /* Flags to attempt. */
unsigned int flags = 0;
- int managed_save = vshCommandOptBool(cmd, "managed-save");
+ /* User-requested actions. */
+ bool managed_save = vshCommandOptBool(cmd, "managed-save");
+ bool snapshots_metadata = vshCommandOptBool(cmd, "snapshots-metadata");
+ /* Positive if these items exist. */
int has_managed_save = 0;
+ int has_snapshots_metadata = 0;
+ int has_snapshots = 0;
+ /* True if undefine will not strand data, even on older servers. */
+ bool managed_save_safe = false;
+ bool snapshots_safe = false;
int rc = -1;
+ int running;
- if (managed_save)
+ if (managed_save) {
flags |= VIR_DOMAIN_UNDEFINE_MANAGED_SAVE;
-
- if (!managed_save)
- flags = -1;
+ managed_save_safe = true;
+ }
+ if (snapshots_metadata) {
+ flags |= VIR_DOMAIN_UNDEFINE_SNAPSHOTS_METADATA;
+ snapshots_safe = true;
+ }
if (!vshConnectionUsability(ctl, ctl->conn))
return false;
@@ -1460,61 +1475,120 @@ cmdUndefine(vshControl *ctl, const vshCmd *cmd)
if (!(dom = vshCommandOptDomain(ctl, cmd, &name)))
return false;
- has_managed_save = virDomainHasManagedSaveImage(dom, 0);
- if (has_managed_save < 0) {
- if (last_error->code != VIR_ERR_NO_SUPPORT) {
- virshReportError(ctl);
- virDomainFree(dom);
- return false;
- } else {
+ /* Do some flag manipulation. The goal here is to disable bits
+ * from flags to reduce the likelihood of a server rejecting
+ * unknown flag bits, as well as to track conditions which are
+ * safe by default for the given hypervisor and server version. */
+ running = virDomainIsActive(dom);
+ if (running < 0) {
+ virshReportError(ctl);
+ goto cleanup;
+ }
+ if (!running) {
+ /* Undefine with snapshots only fails for inactive domains,
+ * and managed save only exists on inactive domains; if
+ * running, then we don't want to remove anything. */
+ has_managed_save = virDomainHasManagedSaveImage(dom, 0);
+ if (has_managed_save < 0) {
+ if (last_error->code != VIR_ERR_NO_SUPPORT) {
+ virshReportError(ctl);
+ goto cleanup;
+ }
virFreeError(last_error);
last_error = NULL;
+ has_managed_save = 0;
}
- }
-
- if (flags == -1) {
- if (has_managed_save == 1) {
- vshError(ctl,
- _("Refusing to undefine while domain managed save "
- "image exists"));
- virDomainFree(dom);
- return false;
- }
-
- rc = virDomainUndefine(dom);
- } else {
- rc = virDomainUndefineFlags(dom, flags);
- /* It might fail when virDomainUndefineFlags is not
- * supported on older libvirt, try to undefine the
- * domain with combo virDomainManagedSaveRemove and
- * virDomainUndefine.
- */
- if (rc < 0) {
+ has_snapshots = virDomainSnapshotNum(dom, 0);
+ if (has_snapshots < 0) {
if (last_error->code != VIR_ERR_NO_SUPPORT) {
virshReportError(ctl);
- goto end;
- } else {
+ goto cleanup;
+ }
+ virFreeError(last_error);
+ last_error = NULL;
+ has_snapshots = 0;
+ }
+ if (has_snapshots) {
+ has_snapshots_metadata
+ = virDomainSnapshotNum(dom, VIR_DOMAIN_SNAPSHOT_LIST_METADATA);
+ if (has_snapshots_metadata < 0) {
+ /* The server did not know the new flag, assume that all
+ snapshots have metadata. */
virFreeError(last_error);
last_error = NULL;
+ has_snapshots_metadata = has_snapshots;
+ } else {
+ /* The server knew the new flag, all aspects of
+ * undefineFlags are safe. */
+ managed_save_safe = snapshots_safe = true;
}
+ }
+ }
+ if (!has_managed_save) {
+ flags &= ~VIR_DOMAIN_UNDEFINE_MANAGED_SAVE;
+ managed_save_safe = true;
+ }
+ if (has_snapshots == 0) {
+ snapshots_safe = true;
+ }
+ if (has_snapshots_metadata == 0) {
+ flags &= ~VIR_DOMAIN_UNDEFINE_SNAPSHOTS_METADATA;
+ snapshots_safe = true;
+ }
- if ((has_managed_save == 1) &&
- virDomainManagedSaveRemove(dom, 0) < 0)
- goto end;
+ /* Generally we want to try the new API first. However, while
+ * virDomainUndefineFlags was introduced at the same time as
+ * VIR_DOMAIN_UNDEFINE_MANAGED_SAVE in 0.9.4, the
+ * VIR_DOMAIN_UNDEFINE_SNAPSHOTS_METADATA flag was not present
+ * until 0.9.5; skip to piecewise emulation if we couldn't prove
+ * above that the new API is safe. */
+ if (managed_save_safe && snapshots_safe) {
+ rc = virDomainUndefineFlags(dom, flags);
+ if (rc == 0 || (last_error->code != VIR_ERR_NO_SUPPORT &&
+ last_error->code != VIR_ERR_INVALID_ARG))
+ goto out;
+ virFreeError(last_error);
+ last_error = NULL;
+ }
- rc = virDomainUndefine(dom);
+ /* The new API is unsupported or unsafe; fall back to doing things
+ * piecewise. */
+ if (has_managed_save) {
+ if (!managed_save) {
+ vshError(ctl, "%s",
+ _("Refusing to undefine while domain managed save "
+ "image exists"));
+ goto cleanup;
+ }
+ if (virDomainManagedSaveRemove(dom, 0) < 0) {
+ virshReportError(ctl);
+ goto cleanup;
}
}
-end:
+ /* No way to emulate deletion of just snapshot metadata
+ * without support for the newer flags. Oh well. */
+ if (has_snapshots_metadata) {
+ vshError(ctl,
+ snapshots_metadata ?
+ _("Unable to remove metadata of %d snapshots") :
+ _("Refusing to undefine while %d snapshots exist"),
+ has_snapshots_metadata);
+ goto cleanup;
+ }
+
+ rc = virDomainUndefine(dom);
+
+out:
if (rc == 0) {
vshPrint(ctl, _("Domain %s has been undefined\n"), name);
+ ret = true;
} else {
vshError(ctl, _("Failed to undefine domain %s"), name);
- ret = false;
}
+cleanup:
virDomainFree(dom);
return ret;
}
diff --git a/tools/virsh.pod b/tools/virsh.pod
index 2c8d66c..e5d6b71 100644
--- a/tools/virsh.pod
+++ b/tools/virsh.pod
@@ -496,6 +496,11 @@ the B<shutdown> command instead. However, this does not delete any
storage volumes used by the guest, and if the domain is persistent, it
can be restarted later.
+If I<domain-id> is transient, then the metadata of any snapshots will
+be lost once the guest stops running, but the snapshot contents still
+exist, and a new domain with the same name and UUID can restore the
+snapshot metadata with B<snapshot-create>.
+
=item B<domblkstat> I<domain> I<block-device>
Get device block stats for a running domain.
@@ -998,6 +1003,11 @@ services must be shutdown in the domain.
The exact behavior of a domain when it shuts down is set by the
I<on_shutdown> parameter in the domain's XML definition.
+If I<domain-id> is transient, then the metadata of any snapshots will
+be lost once the guest stops running, but the snapshot contents still
+exist, and a new domain with the same name and UUID can restore the
+snapshot metadata with B<snapshot-create>.
+
=item B<start> I<domain-name> [I<--console>] [I<--paused>] [I<--autodestroy>]
[I<--bypass-cache>] [I<--force-boot>]
@@ -1029,16 +1039,22 @@ hypervisor.
Output the device used for the TTY console of the domain. If the information
is not available the processes will provide an exit code of 1.
-=item B<undefine> I<domain-id> [I<--managed-save>]
+=item B<undefine> I<domain-id> [I<--managed-save>] [I<--snapshots-metadata]
Undefine a domain. If the domain is running, this converts it to a
transient domain, without stopping it. If the domain is inactive,
the domain configuration is removed.
-The I<--managed-save> flag guarantees that any managed save image(see
+The I<--managed-save> flag guarantees that any managed save image (see
the B<managedsave> command) is also cleaned up. Without the flag, attempts
to undefine a domain with a managed save image will fail.
+The I<--snapshots-metadata> flag guarantees that any snapshots (see the
+B<snapshot-list> command) are also cleaned up when undefining an inactive
+domain. Without the flag, attempts to undefine an inactive domain with
+snapshot metadata will fail. If the domain is active, this flag is
+ignored.
+
NOTE: For an inactive domain, the domain name or UUID must be used as the
I<domain-id>.
@@ -1701,6 +1717,11 @@ treat the snapshot as current, and cannot revert to the snapshot
unless I<--redefine> is later used to teach libvirt about the
metadata again).
+Existence of snapshot metadata will prevent attempts to B<undefine>
+a persistent domain. However, for transient domains, snapshot
+metadata is silently lost when the domain quits running (whether
+by command such as B<destroy> or by internal guest action).
+
=item B<snapshot-create-as> I<domain> {[I<--print-xml>] | [I<--no-metadata>]}
[I<name>] [I<description>]
--
1.7.4.4
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