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qemuSnapshotCreateActiveExternal: Don't thaw filesystems when freeze fails

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If we didn't freeze any filesystems we should not even attempt thawing
them. Additionally 'guest-fsfreeze-freeze' fails if the filesystems are
already frozen, where thawing them may break users data integrity if
they used VIR_DOMAIN_SNAPSHOT_CREATE_QUIESCE accidentally after an
explicit virDomainFSFreeze and the next snapshot without that flag would
be taken with already thawed filesystems.

This effectively reverts 7c736bab06479ccec59df69fb79a5c06d112d8fb .
Libvirt nowadays checks whether the guest agent is connected and pings
it before issuing an command so it's very unlikely that we'd end up in a
situation where qemuSnapshotCreateActiveExternal froze filesystems and
didn't thaw them.

Additionally we now discourage the use of
VIR_DOMAIN_SNAPSHOT_CREATE_QUIESCE since users have better control if
they freeze the FS themselves.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>
This commit is contained in:
Peter Krempa 2021-02-15 17:52:24 +01:00
parent ec86b8fa29
commit ee91c82533
1 changed files with 12 additions and 16 deletions
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28
src/qemu/qemu_snapshot.c
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@ -1403,7 +1403,7 @@ qemuSnapshotCreateActiveExternal(virQEMUDriverPtr driver,
virDomainSnapshotDefPtr snapdef = virDomainSnapshotObjGetDef(snap);
bool memory = snapdef->memory == VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL;
bool memory_unlink = false;
int thaw = 0; /* 1 if freeze succeeded, -1 if freeze failed */
bool thaw = false;
bool pmsuspended = false;
int compressed;
g_autoptr(virCommand) compressor = NULL;
@ -1415,7 +1415,7 @@ qemuSnapshotCreateActiveExternal(virQEMUDriverPtr driver,
* The command will fail if the guest is paused or the guest agent
* is not running, or is already quiesced. */
if (flags & VIR_DOMAIN_SNAPSHOT_CREATE_QUIESCE) {
int freeze;
int frozen;
if (qemuDomainObjBeginAgentJob(driver, vm, QEMU_AGENT_JOB_MODIFY) < 0)
goto cleanup;
@ -1425,16 +1425,14 @@ qemuSnapshotCreateActiveExternal(virQEMUDriverPtr driver,
goto cleanup;
}
freeze = qemuSnapshotFSFreeze(vm, NULL, 0);
frozen = qemuSnapshotFSFreeze(vm, NULL, 0);
qemuDomainObjEndAgentJob(vm);
if (freeze < 0) {
/* the helper reported the error */
if (freeze == -2)
thaw = -1; /* the command is sent but agent failed */
if (frozen < 0)
goto cleanup;
}
thaw = 1;
if (frozen > 0)
thaw = true;
}
/* We need to track what state the guest is in, since taking the
@ -1527,7 +1525,7 @@ qemuSnapshotCreateActiveExternal(virQEMUDriverPtr driver,
QEMU_ASYNC_JOB_SNAPSHOT, 0);
virDomainAuditStop(vm, "from-snapshot");
resume = false;
thaw = 0;
thaw = false;
virObjectEventStateQueue(driver->domainEventState, event);
} else if (memory && pmsuspended) {
/* qemu 1.3 is unable to save a domain in pm-suspended (S3)
@ -1559,14 +1557,12 @@ qemuSnapshotCreateActiveExternal(virQEMUDriverPtr driver,
ret = -1;
}
if (thaw != 0 &&
if (thaw &&
qemuDomainObjBeginAgentJob(driver, vm, QEMU_AGENT_JOB_MODIFY) >= 0 &&
virDomainObjIsActive(vm)) {
if (qemuSnapshotFSThaw(vm, ret == 0 && thaw > 0) < 0) {
/* helper reported the error, if it was needed */
if (thaw > 0)
ret = -1;
}
/* report error only on an otherwise successful snapshot */
if (qemuSnapshotFSThaw(vm, ret == 0) < 0)
ret = -1;
qemuDomainObjEndAgentJob(vm);
}