[PATCH 3/3] qemuSnapshotFSFreeze: Don't return -2

[Peter Krempa]

On Mon, Feb 15, 2021 at 19:20:25 +0100, Pavel Hrdina wrote:
> On Mon, Feb 15, 2021 at 06:27:51PM +0100, Peter Krempa wrote:
> > The -2 value is misleading because if 'qemuAgentFSFreeze' fails it
> > doesn't necessarily mean that the command was sent to the agent.
> > 
> > Since callers don't care about the -2 value specifically, remove it.
> 
> In addition this indirectly fixes virDomainFSFreeze public API where
> we return result of qemuSnapshotFSFreeze directly. Now we comply with
> the API description.

Luckily -2 happens only internally, so we never broke any public API
promise:

This is caused by virNetServerProgramDispatchCall treating any negative
value as error and transporting it over RPC and then
virNetClientProgramCall in the client returning -1 if the returned reply
is of VIR_NET_ERROR type.

Thread 1 "virsh" hit Breakpoint 1, virDomainFSFreeze (dom=dom at entry=0x55555569b550, mountpoints=0x0, nmountpoints=0, flags=flags at entry=0) at ../../../libvirt/src/libvirt-domain.c:11327
11327	{
(gdb) next
11328	    VIR_DOMAIN_DEBUG(dom, "mountpoints=%p, nmountpoints=%d, flags=0x%x",
(gdb)
11331	    virResetLastError();
(gdb)
11333	    virCheckDomainReturn(dom, -1);
(gdb)
11334	    virCheckReadOnlyGoto(dom->conn->flags, error);
(gdb)
11335	    virCheckNonNullArrayArgGoto(mountpoints, nmountpoints, error);
(gdb)
11337	    if (dom->conn->driver->domainFSFreeze) {
(gdb)
11338	        int ret = dom->conn->driver->domainFSFreeze(
(gdb)
11340	        if (ret < 0)
(gdb) p ret
$1 = -1
(gdb) c
Continuing.
error: Unable to freeze filesystems
error: internal error: unable to execute QEMU agent command 'guest-fsfreeze-freeze': The command guest-fsfreeze-freeze has been disabled for this instance