Re: [libvirt] [PATCH v3 2/2] virsh: introduce flage --direct for save command

From: Chen Hanxiao <chenhanxiao(a)gmail.com&gt; Base upon patches from Roy Keene <rkeene(a)knightpoint.com&gt; This patch introduces --direct flag for save command. We could use this flag to save vm to a PIPE. We could saving a VM state directly to Ceph RBD images without having an intermediate file. How to test: fifo="$(mktemp -u)"; mkfifo "${fifo}" && virsh save --pipe cirros "${fifo}" & cat "${fifo}" | rbd --id cinder import - hotsnapshot/test1234 & wait; rm -f "${fifo}"

Signed-off-by: Roy Keene <rkeene(a)knightpoint.com&gt; Signed-off-by: Chen Hanxiao <chenhanxiao(a)gmail.com&gt; --- v3: rebase on upstream v2-resend: rebase on upstream v2: rename VIR_DOMAIN_SAVE_PIPE to VIR_DOMAIN_SAVE_DIRECT tools/virsh-domain.c | 6 ++++++ tools/virsh.pod | 5 ++++- 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/tools/virsh-domain.c b/tools/virsh-domain.c index 09a9f82..d96e894 100644 --- a/tools/virsh-domain.c +++ b/tools/virsh-domain.c @@ -4192,6 +4192,10 @@ static const vshCmdOptDef opts_save[] = { .type = VSH_OT_BOOL, .help = N_("set domain to be paused on restore") }, + {.name = "direct", + .type = VSH_OT_BOOL, + .help = N_("write the file directly, needed by PIPE/FIFO")

+ }, {.name = "verbose", .type = VSH_OT_BOOL, .help = N_("display the progress of save") @@ -4228,6 +4232,8 @@ doSave(void *opaque) flags |= VIR_DOMAIN_SAVE_RUNNING; if (vshCommandOptBool(cmd, "paused")) flags |= VIR_DOMAIN_SAVE_PAUSED; + if (vshCommandOptBool(cmd, "direct")) + flags |= VIR_DOMAIN_SAVE_DIRECT; if (vshCommandOptStringReq(ctl, cmd, "xml", &xmlfile) < 0) goto out; diff --git a/tools/virsh.pod b/tools/virsh.pod index ee79046..9dcb527 100644 --- a/tools/virsh.pod +++ b/tools/virsh.pod @@ -1928,7 +1928,7 @@ have also reverted all storage volumes back to the same contents as when the state file was created. =item B<save> I<domain> I<state-file> [I<--bypass-cache>] [I<--xml> B<file>] -[{I<--running> | I<--paused>}] [I<--verbose>] +[{I<--running> | I<--paused>}] [I<--direct>] [I<--verbose>] Saves a running domain (RAM, but not disk state) to a state file so that it can be restored @@ -1943,6 +1943,9 @@ with B<domjobabort> command (sent by another virsh instance). Another option is to send SIGINT (usually with C<Ctrl-C>) to the virsh process running B<save> command. I<--verbose> displays the progress of save. +Usually B<save> command will save the domain's state as a regular file. +If you want to save it into a PIPE/FIFO, then flag I<--direct> must be set. +

This is roughly equivalent to doing a hibernate on a running computer, with all the same limitations. Open network connections may be severed upon restore, as TCP timeouts may have expired.