[libvirt] [PATCHv2] xml: introduce startupPolicy for chardev device

From: Seiji Aguchi <seiji.aguchi(a)hds.com&gt; [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 cases 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=e5a84d74a278 Signed-off-by: Seiji Aguchi <seiji.aguchi(a)hds.com&gt; Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- Seiji's patch plus my initial review comments; I've ack'd this much, but want to add a round-trip xml2xml test before pushing anything (Seiji, if you want to use this as a starting point, rather than waiting for my long weekend, feel free to post a v3). docs/formatdomain.html.in | 15 ++++++++++++++- docs/schemas/domaincommon.rng | 3 +++ src/conf/domain_conf.c | 8 ++++++++ src/conf/domain_conf.h | 1 + src/qemu/qemu_process.c | 23 ++++++++++++++++------- tests/virt-aa-helper-test | 3 +++ 6 files changed, 45 insertions(+), 8 deletions(-) diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index 755d084..299fa49 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -4212,13 +4212,26 @@ 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. + <span class="since">Since 1.0.6</span>, it is possible to define + policy on what happens if the file is not accessible when + booting or migrating. This is done by + a <code>startupPolicy</code> attribute: </p> + <ul> + <li>If the value is "mandatory" (the default), the guest fails + to boot or migrate if the file is not found.</li> + <li>If the value is "optional", a missing file is at boot or + migration is substituted with /dev/null, so the guest still sees + the device but the host no longer tracks guest data on the device.</li> + <li>If the value is "requisite", the file is required for + booting, but optional on migration.</li> + </ul> <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 3cace35..e8eec6c 100644 --- a/docs/schemas/domaincommon.rng +++ b/docs/schemas/domaincommon.rng @@ -2780,6 +2780,9 @@ </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 a9656af..c24a9f0 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -6626,6 +6626,7 @@ virDomainChrSourceDefParseXML(virDomainChrSourceDefPtr def, char *path = NULL; char *mode = NULL; char *protocol = NULL; + char *startupPolicy = NULL; int remaining = 0; while (cur != NULL) { @@ -6646,6 +6647,9 @@ 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: @@ -6718,6 +6722,10 @@ 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 3a71d6c..4d49dd5 100644 --- a/src/conf/domain_conf.h +++ b/src/conf/domain_conf.h @@ -1074,6 +1074,7 @@ 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 d4fd4fb..154445d 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -2439,15 +2439,24 @@ qemuProcessPrepareChardevDevice(virDomainDefPtr def ATTRIBUTE_UNUSED, return 0; 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; + O_CREAT | O_APPEND | O_RDONLY, S_IRUSR|S_IWUSR)) < 0) { + if (dev->source.data.file.startupPolicy != + VIR_DOMAIN_STARTUP_POLICY_OPTIONAL) { + virReportSystemError(errno, + _("Unable to pre-create chardev file '%s'"), + dev->source.data.file.path); + return -1; + } + /* Change destination to /dev/null to work around missing file. */ + VIR_WARN("chardev file '%s' not found, switching to /dev/null", + dev->source.data.file.path); + VIR_FREE(dev->source.data.file.path); + if (VIR_STRDUP(dev->source.data.file.path, "/dev/null") < 0) + return -1; + } else { + VIR_FORCE_CLOSE(fd); } - VIR_FORCE_CLOSE(fd); - return 0; } 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" -- 1.8.1.4