[libvirt] [PATCH] Introduce startupPolicy for chardev to make guest OS bootable when hardware failure happens in log disk
Seiji Aguchi
seiji.aguchi at hds.com
Sat May 11 00:10:38 UTC 2013
Any comments?
> -----Original Message-----
> From: Seiji Aguchi
> Sent: Thursday, May 02, 2013 1:26 PM
> To: libvir-list at redhat.com
> Cc: dle-develop at lists.sourceforge.net; Tomoki Sekiyama (tomoki.sekiyama at hds.com)
> Subject: [PATCH] Introduce startupPolicy for chardev to make guest OS bootable when hardware failure happens in log disk
>
> [Problem]
> Currently, guest OS's messages can be logged to a local disk of host OS
> by creating chadevs with options below.
> -chardev file,id=charserial0,path=<log file's path> -device isa-serial,chardev=chardevserial0,id=serial0
>
> When a hardware failure happens in the disk, qemu-kvm can't create the chardevs.
> In this case, guest OS doesn't boot up.
>
> Actually, there are users who don't desire that guest OS goes down due to a hardware failure
> of a log disk only.Therefore, qemu should offer some way to boot guest OS up even if the log
> disk is broken.
>
> [Solution]
> This patch supports startupPolicy for chardev.
>
> The starupPolicy is introduced just in case where chardev is "file"
> because this patch aims for making guest OS boot up when a hardware failure happens.
>
> In other cases ,pty, dev, pipe and unix, it is not introduced
> because they don't access to hardware.
>
> The policy works as follows.
> - If the value is "optional", guestOS boots up by dropping the chardev.
> - If other values are specified, guestOS fails to boot up. (the default)
>
> Description about original startupPolicy attribute:
> http://libvirt.org/git/?p=libvirt.git;a=commitdiff;h=e5a84d74a2789a917bf394f15de9989ec48fded0
>
> Signed-off-by: Seiji Aguchi <seiji.aguchi at hds.com>
> ---
> docs/formatdomain.html.in | 9 ++++++++-
> docs/schemas/domaincommon.rng | 3 +++
> src/conf/domain_conf.c | 8 ++++++++
> src/conf/domain_conf.h | 1 +
> src/qemu/qemu_process.c | 25 ++++++++++++++++++++++++-
> tests/virt-aa-helper-test | 3 +++
> 6 files changed, 47 insertions(+), 2 deletions(-)
>
> diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
> index f325c3c..1e1bf27 100644
> --- a/docs/formatdomain.html.in
> +++ b/docs/formatdomain.html.in
> @@ -4044,13 +4044,20 @@ qemu-kvm -net nic,model=? /dev/null
> <p>
> A file is opened and all data sent to the character
> device is written to the file.
> + It is possible to define policy whether guestOS boots up
> + if the file is not accessible. This is done by a startupPolicy
> + attribute:
> + <ul>
> + <li>If the vaule is "optional", guestOS boots up by dropping the file.</li>
> + <li>If other values are specified, guestOS fails to boot up. (the default)</li>
> + </ul>
> </p>
>
> <pre>
> ...
> <devices>
> <serial type="file">
> - <source path="/var/log/vm/vm-serial.log"/>
> + <source path="/var/log/vm/vm-serial.log" startupPolicy="optional"/>
> <target port="1"/>
> </serial>
> </devices>
> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
> index 10596dc..6fc0a3c 100644
> --- a/docs/schemas/domaincommon.rng
> +++ b/docs/schemas/domaincommon.rng
> @@ -2706,6 +2706,9 @@
> </optional>
> <optional>
> <attribute name="path"/>
> + <optional>
> + <ref name='startupPolicy'/>
> + </optional>
> </optional>
> <optional>
> <attribute name="host"/>
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index a8b5dfd..6680f15 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -6467,6 +6467,7 @@ virDomainChrSourceDefParseXML(virDomainChrSourceDefPtr def,
> char *path = NULL;
> char *mode = NULL;
> char *protocol = NULL;
> + char *startupPolicy = NULL;
> int remaining = 0;
>
> while (cur != NULL) {
> @@ -6487,6 +6488,9 @@ virDomainChrSourceDefParseXML(virDomainChrSourceDefPtr def,
> !(flags & VIR_DOMAIN_XML_INACTIVE)))
> path = virXMLPropString(cur, "path");
>
> + if (startupPolicy == NULL &&
> + def->type == VIR_DOMAIN_CHR_TYPE_FILE)
> + startupPolicy = virXMLPropString(cur, "startupPolicy");
> break;
>
> case VIR_DOMAIN_CHR_TYPE_UDP:
> @@ -6559,6 +6563,10 @@ virDomainChrSourceDefParseXML(virDomainChrSourceDefPtr def,
>
> def->data.file.path = path;
> path = NULL;
> +
> + def->data.file.startupPolicy =
> + virDomainStartupPolicyTypeFromString(startupPolicy);
> + startupPolicy = NULL;
> break;
>
> case VIR_DOMAIN_CHR_TYPE_STDIO:
> diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
> index 3a0f23a..e709951 100644
> --- a/src/conf/domain_conf.h
> +++ b/src/conf/domain_conf.h
> @@ -1052,6 +1052,7 @@ struct _virDomainChrSourceDef {
> /* no <source> for null, vc, stdio */
> struct {
> char *path;
> + int startupPolicy; /* enum virDomainStartupPolicy */
> } file; /* pty, file, pipe, or device */
> struct {
> char *host;
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index e75c8c9..6e2f78e 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -2442,7 +2442,30 @@ qemuProcessPrepareChardevDevice(virDomainDefPtr def ATTRIBUTE_UNUSED,
> virReportSystemError(errno,
> _("Unable to pre-create chardev file '%s'"),
> dev->source.data.file.path);
> - return -1;
> + if (dev->source.data.file.startupPolicy !=
> + VIR_DOMAIN_STARTUP_POLICY_OPTIONAL) {
> + return -1;
> + }
> + VIR_FREE(dev->source.data.file.path);
> + /*
> + * Change a destination to /dev/null to boot guest OS up
> + * even if a log disk is broken.
> + */
> + VIR_WARN("Switch the destination to /dev/null");
> + dev->source.data.file.path = strdup("/dev/null");
> +
> + if (!(dev->source.data.file.path)) {
> + virReportOOMError();
> + return -1;
> + }
> +
> + if ((fd = open(dev->source.data.file.path,
> + O_CREAT | O_APPEND, S_IRUSR|S_IWUSR)) < 0) {
> + virReportSystemError(errno,
> + _("Unable to pre-create chardev file '%s'"),
> + dev->source.data.file.path);
> + return -1;
> + }
> }
>
> VIR_FORCE_CLOSE(fd);
> diff --git a/tests/virt-aa-helper-test b/tests/virt-aa-helper-test
> index af91c61..7172fd6 100755
> --- a/tests/virt-aa-helper-test
> +++ b/tests/virt-aa-helper-test
> @@ -255,6 +255,9 @@ testme "0" "disk (empty cdrom)" "-r -u $valid_uuid" "$test_xml"
> sed -e "s,###UUID###,$uuid,g" -e "s,###DISK###,$disk1,g" -e "s,</devices>,<serial type='file'><source
> path='$tmpdir/serial.log'/><target port='0'/></serial></devices>,g" "$template_xml" > "$test_xml"
> testme "0" "serial" "-r -u $valid_uuid" "$test_xml"
>
> +sed -e "s,###UUID###,$uuid,g" -e "s,###DISK###,$disk1,g" -e "s,</devices>,<serial type='file'><source path='$tmpdir/serial.log'
> startupPolicy='optional'/><target port='0'/></serial></devices>,g" "$template_xml" > "$test_xml"
> +testme "0" "serial" "-r -u $valid_uuid" "$test_xml"
> +
> sed -e "s,###UUID###,$uuid,g" -e "s,###DISK###,$disk1,g" -e "s,</devices>,<serial type='pty'><target
> port='0'/></serial></devices>,g" "$template_xml" > "$test_xml"
> testme "0" "serial (pty)" "-r -u $valid_uuid" "$test_xml"
>
> --
> 1.7.1
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