9:15 p.m.
This series introduce flag VIR_DOMAIN_SAVE_DIRECT
to enable command 'save' to write to PIPE.
Base upon patches from Roy Keene <rkeene(a)knightpoint.com>
with some fixes.
Change from original patch:
1) Check whether the specified path is a PIPE.
2) Rebase on upstream.
3) Add doc for virsh command
v2:
rename VIR_DOMAIN_SAVE_PIPE to VIR_DOMAIN_SAVE_DIRECT
remove S_ISFIFO check
Chen Hanxiao (2):
qemu: Allow saving QEMU libvirt state to a pipe
virsh: introduce flage --direct for save command
include/libvirt/libvirt-domain.h | 1 +
src/qemu/qemu_driver.c | 54 ++++++++++++++++++++++++++--------------
tools/virsh-domain.c | 6 +++++
tools/virsh.pod | 5 +++-
4 files changed, 47 insertions(+), 19 deletions(-)
--
2.7.4
9:15 p.m.
New subject: [libvirt] [PATCH v2 1/2] qemu: Allow saving QEMU libvirt state to a pipe
From: Chen Hanxiao <chenhanxiao(a)gmail.com>
Base upon patches from Roy Keene <rkeene(a)knightpoint.com>
Currently qemuDomainSaveMemory can save vm's config
and memory to fd.
It write a magic QEMU_SAVE_PARTIAL firstly,
then re-open it to change QEMU_SAVE_PARTIAL as QEMU_SAVE_MAGIC.
For pipes this is not possible, attempting to re-open the pipe
will not connect you to the same consumer.
Seeking is also not possible on a pipe.
This patch introduce VIR_DOMAIN_SAVE_DIRECT
If set, write QEMU_SAVE_MAGIC directly.
This is useful to me for saving a VM state directly to
Ceph RBD images without having an intermediate file.
Signed-off-by: Roy Keene <rkeene(a)knightpoint.com>
Signed-off-by: Chen Hanxiao <chenhanxiao(a)gmail.com>
---
v2:
rename VIR_DOMAIN_SAVE_PIPE to VIR_DOMAIN_SAVE_DIRECT
remove S_ISFIFO check for dst path
include/libvirt/libvirt-domain.h | 1 +
src/qemu/qemu_driver.c | 54 ++++++++++++++++++++++++++--------------
2 files changed, 37 insertions(+), 18 deletions(-)
diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-domain.h
index 3290b10..48865a8 100644
--- a/include/libvirt/libvirt-domain.h
+++ b/include/libvirt/libvirt-domain.h
@@ -1169,6 +1169,7 @@ typedef enum {
VIR_DOMAIN_SAVE_BYPASS_CACHE = 1 << 0, /* Avoid file system cache pollution */
VIR_DOMAIN_SAVE_RUNNING = 1 << 1, /* Favor running over paused */
VIR_DOMAIN_SAVE_PAUSED = 1 << 2, /* Favor paused over running */
+ VIR_DOMAIN_SAVE_DIRECT = 1 << 3, /* Write QEMU_SAVE_MAGIC directly */
} virDomainSaveRestoreFlags;
int virDomainSave (virDomainPtr domain,
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 88778d4..76b25ad 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -3051,6 +3051,7 @@ qemuDomainSaveMemory(virQEMUDriverPtr driver,
virQEMUSaveHeader header;
bool bypassSecurityDriver = false;
bool needUnlink = false;
+ bool canReopen = true;
int ret = -1;
int fd = -1;
int directFlag = 0;
@@ -3058,7 +3059,6 @@ qemuDomainSaveMemory(virQEMUDriverPtr driver,
unsigned int wrapperFlags = VIR_FILE_WRAPPER_NON_BLOCKING;
memset(&header, 0, sizeof(header));
- memcpy(header.magic, QEMU_SAVE_PARTIAL, sizeof(header.magic));
header.version = QEMU_SAVE_VERSION;
header.was_running = was_running ? 1 : 0;
header.compressed = compressed;
@@ -3074,6 +3074,7 @@ qemuDomainSaveMemory(virQEMUDriverPtr driver,
goto cleanup;
}
}
+
fd = qemuOpenFile(driver, vm, path,
O_WRONLY | O_TRUNC | O_CREAT | directFlag,
&needUnlink, &bypassSecurityDriver);
@@ -3086,6 +3087,20 @@ qemuDomainSaveMemory(virQEMUDriverPtr driver,
if (!(wrapperFd = virFileWrapperFdNew(&fd, path, wrapperFlags)))
goto cleanup;
+ /* Set the header magic.
+ * Setting flags VIR_DOMAIN_SAVE_DIRECT will write
+ * magic QEMU_SAVE_MAGIC directly.
+ * For PIPE, we should do this because it can't be reopen.
+ * Otherwise we'll update the magic after
+ * the saving completes successfully.
+ */
+ if (flags & VIR_DOMAIN_SAVE_DIRECT) {
+ canReopen = false;
+ memcpy(header.magic, QEMU_SAVE_MAGIC, sizeof(header.magic));
+ } else {
+ memcpy(header.magic, QEMU_SAVE_PARTIAL, sizeof(header.magic));
+ }
+
/* Write header to file, followed by XML */
if (qemuDomainSaveHeader(fd, path, domXML, &header) < 0)
goto cleanup;
@@ -3094,28 +3109,30 @@ qemuDomainSaveMemory(virQEMUDriverPtr driver,
if (qemuMigrationToFile(driver, vm, fd, compressedpath, asyncJob) < 0)
goto cleanup;
- /* Touch up file header to mark image complete. */
+ if (canReopen) {
+ /* Touch up file header to mark image complete. */
- /* Reopen the file to touch up the header, since we aren't set
- * up to seek backwards on wrapperFd. The reopened fd will
- * trigger a single page of file system cache pollution, but
- * that's acceptable. */
- if (VIR_CLOSE(fd) < 0) {
- virReportSystemError(errno, _("unable to close %s"), path);
- goto cleanup;
- }
+ /* Reopen the file to touch up the header, since we aren't set
+ * up to seek backwards on wrapperFd. The reopened fd will
+ * trigger a single page of file system cache pollution, but
+ * that's acceptable. */
+ if (VIR_CLOSE(fd) < 0) {
+ virReportSystemError(errno, _("unable to close %s"), path);
+ goto cleanup;
+ }
- if (virFileWrapperFdClose(wrapperFd) < 0)
- goto cleanup;
+ if (virFileWrapperFdClose(wrapperFd) < 0)
+ goto cleanup;
- if ((fd = qemuOpenFile(driver, vm, path, O_WRONLY, NULL, NULL)) < 0)
- goto cleanup;
+ if ((fd = qemuOpenFile(driver, vm, path, O_WRONLY, NULL, NULL)) < 0)
+ goto cleanup;
- memcpy(header.magic, QEMU_SAVE_MAGIC, sizeof(header.magic));
+ memcpy(header.magic, QEMU_SAVE_MAGIC, sizeof(header.magic));
- if (safewrite(fd, &header, sizeof(header)) != sizeof(header)) {
- virReportSystemError(errno, _("unable to write %s"), path);
- goto cleanup;
+ if (safewrite(fd, &header, sizeof(header)) != sizeof(header)) {
+ virReportSystemError(errno, _("unable to write %s"), path);
+ goto cleanup;
+ }
}
if (VIR_CLOSE(fd) < 0) {
@@ -3345,6 +3362,7 @@ qemuDomainSaveFlags(virDomainPtr dom, const char *path, const char
*dxml,
virCheckFlags(VIR_DOMAIN_SAVE_BYPASS_CACHE |
VIR_DOMAIN_SAVE_RUNNING |
+ VIR_DOMAIN_SAVE_DIRECT |
VIR_DOMAIN_SAVE_PAUSED, -1);
cfg = virQEMUDriverGetConfig(driver);
--
2.7.4
9:15 p.m.
New subject: [libvirt] [PATCH v2 2/2] virsh: introduce flage --direct for save command
From: Chen Hanxiao <chenhanxiao(a)gmail.com>
Base upon patches from Roy Keene <rkeene(a)knightpoint.com>
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 --direct
cirros "${fifo}" &
cat "${fifo}" | rbd --id cinder import - hotsnapshot/test1234 & wait; rm -f
"${fifo}"
Signed-off-by: Roy Keene <rkeene(a)knightpoint.com>
Signed-off-by: Chen Hanxiao <chenhanxiao(a)gmail.com>
---
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 3a6fa5c..3ab7457 100644
--- a/tools/virsh-domain.c
+++ b/tools/virsh-domain.c
@@ -4187,6 +4187,10 @@ 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")
@@ -4223,6 +4227,8 @@ 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 74c05c9..a2c2cfe 100644
--- a/tools/virsh.pod
+++ b/tools/virsh.pod
@@ -1898,7 +1898,7 @@ 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
@@ -1913,6 +1913,9 @@ 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.
--
2.7.4
3:12 p.m.
At 2016-12-15 11:15:13, "Chen Hanxiao" <chen_han_xiao(a)126.com> wrote:
This series introduce flag VIR_DOMAIN_SAVE_DIRECT
to enable command 'save' to write to PIPE.
Base upon patches from Roy Keene <rkeene(a)knightpoint.com>
with some fixes.
Change from original patch:
1) Check whether the specified path is a PIPE.
2) Rebase on upstream.
3) Add doc for virsh command
v2:
rename VIR_DOMAIN_SAVE_PIPE to VIR_DOMAIN_SAVE_DIRECT
remove S_ISFIFO check
Chen Hanxiao (2):
qemu: Allow saving QEMU libvirt state to a pipe
virsh: introduce flage --direct for save command
Any comments？
Regards,
- Chen
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Chen Hanxiao