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Re: [libvirt] [PATCH] Introduce startupPolicy for chardev to make guest OS bootable when hardware failure happens in log disk



Any comments?

> -----Original Message-----
> From: Seiji Aguchi
> Sent: Thursday, May 02, 2013 1:26 PM
> To: libvir-list redhat com
> Cc: dle-develop lists sourceforge net; Tomoki Sekiyama (tomoki sekiyama 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 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>
>    ...
>    &lt;devices&gt;
>      &lt;serial type="file"&gt;
> -      &lt;source path="/var/log/vm/vm-serial.log"/&gt;
> +      &lt;source path="/var/log/vm/vm-serial.log" startupPolicy="optional"/&gt;
>        &lt;target port="1"/&gt;
>      &lt;/serial&gt;
>    &lt;/devices&gt;
> 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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