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Re: [libvirt] [libvirt PATCH] qemu: Support discard for disk



Il 14/05/2013 14:44, Osier Yang ha scritto:
> QEMU introduced "discard" option for drive since commit a9384aff53,
> 
> <...>
> @var{discard} is one of "ignore" (or "off") or "unmap" (or "on") and
> controls whether @dfn{discard} (also known as @dfn{trim} or @dfn{unmap})
> requests are ignored or passed to the filesystem.  Some machine types
> may not support discard requests.
> </...>
> 
> This patch exposes the support in libvirt.
> 
> QEMU supported "discard" for "-drive" since v1.5.0-rc0:

I would prefer to use ignore/unmap instead of off/on in libvirt.

Paolo

> % git tag --contains a9384aff53
> contains
> v1.5.0-rc0
> v1.5.0-rc1
> 
> So this only detects the capability bit using virQEMUCapsProbeQMPCommandLine.
> 
> ---
> This is on top of https://www.redhat.com/archives/libvir-list/2013-May/msg00979.html
> ---
>  docs/formatdomain.html.in                          |  8 +++++
>  docs/schemas/domaincommon.rng                      | 11 +++++++
>  src/conf/domain_conf.c                             | 18 +++++++++++
>  src/conf/domain_conf.h                             | 10 ++++++
>  src/libvirt_private.syms                           |  1 +
>  src/qemu/qemu_capabilities.c                       |  2 ++
>  src/qemu/qemu_capabilities.h                       |  1 +
>  src/qemu/qemu_command.c                            | 11 +++++++
>  .../qemuxml2argv-disk-drive-discard.args           |  8 +++++
>  .../qemuxml2argv-disk-drive-discard.xml            | 37 ++++++++++++++++++++++
>  tests/qemuxml2argvtest.c                           |  3 ++
>  tests/qemuxml2xmltest.c                            |  2 ++
>  12 files changed, 112 insertions(+)
>  create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-disk-drive-discard.args
>  create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-disk-drive-discard.xml
> 
> diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
> index 9ade507..a73d72e 100644
> --- a/docs/formatdomain.html.in
> +++ b/docs/formatdomain.html.in
> @@ -1681,6 +1681,14 @@
>              network. By default copy-on-read is off.
>              <span class='since'>Since 0.9.10 (QEMU and KVM only)</span>
>            </li>
> +          <li>
> +            The optional <code>discard</code> attribute controls whether
> +            to discard (also known as "trim" or "unmap") requests are
> +            ignored or passed to the filesystem. The value can be either
> +            "on" (allow the discard request to be passed) or "off" (ingore
> +            the discard request).
> +            <span class='since'>Since 1.0.6 (QEMU and KVM only)</span>
> +          </li>
>          </ul>
>        </dd>
>        <dt><code>boot</code></dt>
> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
> index 8004428..2083e95 100644
> --- a/docs/schemas/domaincommon.rng
> +++ b/docs/schemas/domaincommon.rng
> @@ -1304,6 +1304,9 @@
>        <optional>
>          <ref name="copy_on_read"/>
>        </optional>
> +      <optional>
> +        <ref name="discard"/>
> +      </optional>
>        <empty/>
>      </element>
>    </define>
> @@ -1399,6 +1402,14 @@
>          <value>off</value>
>        </choice>
>      </attribute>
> +    </define>
> +  <define name="discard">
> +    <attribute name='discard'>
> +      <choice>
> +        <value>on</value>
> +        <value>off</value>
> +      </choice>
> +    </attribute>
>    </define>
>    <define name="controller">
>      <element name="controller">
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index 862b997..f632c02 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -743,6 +743,10 @@ VIR_ENUM_IMPL(virDomainTPMModel, VIR_DOMAIN_TPM_MODEL_LAST,
>  VIR_ENUM_IMPL(virDomainTPMBackend, VIR_DOMAIN_TPM_TYPE_LAST,
>                "passthrough")
>  
> +VIR_ENUM_IMPL(virDomainDiskDiscard, VIR_DOMAIN_DISK_DISCARD_LAST,
> +              "default",
> +              "on",
> +              "off")
>  
>  #define VIR_DOMAIN_XML_WRITE_FLAGS  VIR_DOMAIN_XML_SECURE
>  #define VIR_DOMAIN_XML_READ_FLAGS   VIR_DOMAIN_XML_INACTIVE
> @@ -4534,6 +4538,7 @@ virDomainDiskDefParseXML(virDomainXMLOptionPtr xmlopt,
>      char *wwn = NULL;
>      char *vendor = NULL;
>      char *product = NULL;
> +    char *discard = NULL;
>      int expected_secret_usage = -1;
>      int auth_secret_usage = -1;
>  
> @@ -4761,6 +4766,7 @@ virDomainDiskDefParseXML(virDomainXMLOptionPtr xmlopt,
>                  ioeventfd = virXMLPropString(cur, "ioeventfd");
>                  event_idx = virXMLPropString(cur, "event_idx");
>                  copy_on_read = virXMLPropString(cur, "copy_on_read");
> +                discard = virXMLPropString(cur, "discard");
>              } else if (!mirror && xmlStrEqual(cur->name, BAD_CAST "mirror") &&
>                         !(flags & VIR_DOMAIN_XML_INACTIVE)) {
>                  char *ready;
> @@ -5207,6 +5213,14 @@ virDomainDiskDefParseXML(virDomainXMLOptionPtr xmlopt,
>          def->copy_on_read = cor;
>      }
>  
> +    if (discard) {
> +        if ((def->discard = virDomainDiskDiscardTypeFromString(discard)) <= 0) {
> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                           _("unknown disk discard mode '%s'"), discard);
> +            goto error;
> +        }
> +    }
> +
>      if (devaddr) {
>          if (virDomainParseLegacyDeviceAddress(devaddr,
>                                                &def->info.addr.pci) < 0) {
> @@ -5326,6 +5340,7 @@ cleanup:
>      VIR_FREE(ioeventfd);
>      VIR_FREE(event_idx);
>      VIR_FREE(copy_on_read);
> +    VIR_FREE(discard);
>      VIR_FREE(devaddr);
>      VIR_FREE(serial);
>      virStorageEncryptionFree(encryption);
> @@ -13642,6 +13657,7 @@ virDomainDiskDefFormat(virBufferPtr buf,
>      const char *event_idx = virDomainVirtioEventIdxTypeToString(def->event_idx);
>      const char *copy_on_read = virDomainVirtioEventIdxTypeToString(def->copy_on_read);
>      const char *sgio = virDomainDiskSGIOTypeToString(def->sgio);
> +    const char *discard = virDomainDiskDiscardTypeToString(def->discard);
>  
>      char uuidstr[VIR_UUID_STRING_BUFLEN];
>  
> @@ -13718,6 +13734,8 @@ virDomainDiskDefFormat(virBufferPtr buf,
>              virBufferAsprintf(buf, " event_idx='%s'", event_idx);
>          if (def->copy_on_read)
>              virBufferAsprintf(buf, " copy_on_read='%s'", copy_on_read);
> +        if (def->discard)
> +            virBufferAsprintf(buf, " discard='%s'", discard);
>          virBufferAddLit(buf, "/>\n");
>      }
>  
> diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
> index a9d3410..67ea91e 100644
> --- a/src/conf/domain_conf.h
> +++ b/src/conf/domain_conf.h
> @@ -625,6 +625,14 @@ enum virDomainDiskSGIO {
>      VIR_DOMAIN_DISK_SGIO_LAST
>  };
>  
> +enum virDomainDiskDiscard {
> +    VIR_DOMAIN_DISK_DISCARD_DEFAULT = 0,
> +    VIR_DOMAIN_DISK_DISCARD_ON,
> +    VIR_DOMAIN_DISK_DISCARD_OFF,
> +
> +    VIR_DOMAIN_DISK_DISCARD_LAST
> +};
> +
>  typedef struct _virDomainBlockIoTuneInfo virDomainBlockIoTuneInfo;
>  struct _virDomainBlockIoTuneInfo {
>      unsigned long long total_bytes_sec;
> @@ -707,6 +715,7 @@ struct _virDomainDiskDef {
>      bool rawio_specified;
>      int rawio; /* no = 0, yes = 1 */
>      int sgio; /* enum virDomainDiskSGIO */
> +    int discard; /* enum virDomainDiskDiscard */
>  
>      size_t nseclabels;
>      virSecurityDeviceLabelDefPtr *seclabels;
> @@ -2462,6 +2471,7 @@ VIR_ENUM_DECL(virDomainDiskIo)
>  VIR_ENUM_DECL(virDomainDiskSecretType)
>  VIR_ENUM_DECL(virDomainDiskSGIO)
>  VIR_ENUM_DECL(virDomainDiskTray)
> +VIR_ENUM_DECL(virDomainDiskDiscard)
>  VIR_ENUM_DECL(virDomainIoEventFd)
>  VIR_ENUM_DECL(virDomainVirtioEventIdx)
>  VIR_ENUM_DECL(virDomainDiskCopyOnRead)
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index cdd0b41..cc734da 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -142,6 +142,7 @@ virDomainDiskDefFree;
>  virDomainDiskDefGenSecurityLabelDef;
>  virDomainDiskDefGetSecurityLabelDef;
>  virDomainDiskDeviceTypeToString;
> +virDomainDiskDiscardTypeToString;
>  virDomainDiskErrorPolicyTypeFromString;
>  virDomainDiskErrorPolicyTypeToString;
>  virDomainDiskFindByBusAndDst;
> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
> index c711e92..e6cb091 100644
> --- a/src/qemu/qemu_capabilities.c
> +++ b/src/qemu/qemu_capabilities.c
> @@ -228,6 +228,7 @@ VIR_ENUM_IMPL(virQEMUCaps, QEMU_CAPS_LAST,
>  
>                "scsi-generic.bootindex", /* 145 */
>                "mem-merge",
> +              "drive-discard",
>      );
>  
>  struct _virQEMUCaps {
> @@ -2243,6 +2244,7 @@ struct virQEMUCapsCommandLineProps {
>  
>  static struct virQEMUCapsCommandLineProps virQEMUCapsCommandLine[] = {
>      { "machine", "mem-merge", QEMU_CAPS_MEM_MERGE },
> +    { "drive", "discard", QEMU_CAPS_DRIVE_DISCARD },
>  };
>  
>  static int
> diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h
> index 477e526..e30a550 100644
> --- a/src/qemu/qemu_capabilities.h
> +++ b/src/qemu/qemu_capabilities.h
> @@ -185,6 +185,7 @@ enum virQEMUCapsFlags {
>      QEMU_CAPS_DEVICE_SCSI_GENERIC = 144,  /* -device scsi-generic */
>      QEMU_CAPS_DEVICE_SCSI_GENERIC_BOOTINDEX = 145,  /* -device scsi-generic.bootindex */
>      QEMU_CAPS_MEM_MERGE          = 146, /* -machine mem-merge */
> +    QEMU_CAPS_DRIVE_DISCARD      = 147, /* -drive discard=off(ignore)|on(unmap) */
>  
>      QEMU_CAPS_LAST,                   /* this must always be the last item */
>  };
> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index eddc263..053f553 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
> @@ -3267,6 +3267,17 @@ qemuBuildDriveStr(virConnectPtr conn ATTRIBUTE_UNUSED,
>          }
>      }
>  
> +    if (disk->discard) {
> +        if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_DRIVE_DISCARD)) {
> +            virBufferAsprintf(&opt, ",discard=%s",
> +                              virDomainDiskDiscardTypeToString(disk->discard));
> +        } else {
> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> +                           _("discard is not supported by this QEMU binary"));
> +            goto error;
> +        }
> +    }
> +
>      if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_MONITOR_JSON)) {
>          const char *wpolicy = NULL, *rpolicy = NULL;
>  
> diff --git a/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-discard.args b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-discard.args
> new file mode 100644
> index 0000000..02e2ddb
> --- /dev/null
> +++ b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-discard.args
> @@ -0,0 +1,8 @@
> +LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test \
> +/usr/bin/qemu -S -M pc-0.13 -m 1024 -smp 1 -nographic -nodefaults \
> +-monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot dc -usb \
> +-drive file=/var/lib/libvirt/images/f14.img,if=none,id=drive-virtio-disk0,discard=on \
> +-device virtio-blk-pci,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0 \
> +-drive file=/var/lib/libvirt/Fedora-14-x86_64-Live-KDE.iso,if=none,media=cdrom,id=drive-ide0-1-0,discard=off \
> +-device ide-drive,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 \
> +-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3
> diff --git a/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-discard.xml b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-discard.xml
> new file mode 100644
> index 0000000..a6a8135
> --- /dev/null
> +++ b/tests/qemuxml2argvdata/qemuxml2argv-disk-drive-discard.xml
> @@ -0,0 +1,37 @@
> +<domain type='qemu'>
> +  <name>test</name>
> +  <uuid>92d7a226-cfae-425b-a6d3-00bbf9ec5c9e</uuid>
> +  <memory unit='KiB'>1048576</memory>
> +  <currentMemory unit='KiB'>1048576</currentMemory>
> +  <vcpu placement='static'>1</vcpu>
> +  <os>
> +    <type arch='x86_64' machine='pc-0.13'>hvm</type>
> +    <boot dev='cdrom'/>
> +    <boot dev='hd'/>
> +    <bootmenu enable='yes'/>
> +  </os>
> +  <clock offset='utc'/>
> +  <on_poweroff>destroy</on_poweroff>
> +  <on_reboot>restart</on_reboot>
> +  <on_crash>restart</on_crash>
> +  <devices>
> +    <emulator>/usr/bin/qemu</emulator>
> +    <disk type='file' device='disk'>
> +      <driver name='qemu' type='qcow2' discard='on'/>
> +      <source file='/var/lib/libvirt/images/f14.img'/>
> +      <target dev='vda' bus='virtio'/>
> +      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
> +    </disk>
> +    <disk type='file' device='cdrom'>
> +      <driver name='qemu' type='raw' discard='off'/>
> +      <source file='/var/lib/libvirt/Fedora-14-x86_64-Live-KDE.iso'/>
> +      <target dev='hdc' bus='ide'/>
> +      <readonly/>
> +      <address type='drive' controller='0' bus='1' target='0' unit='0'/>
> +    </disk>
> +    <controller type='usb' index='0'/>
> +    <controller type='ide' index='0'/>
> +    <controller type='pci' index='0' model='pci-root'/>
> +    <memballoon model='virtio'/>
> +  </devices>
> +</domain>
> diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c
> index 98ceb83..46dd7de 100644
> --- a/tests/qemuxml2argvtest.c
> +++ b/tests/qemuxml2argvtest.c
> @@ -579,6 +579,9 @@ mymain(void)
>              QEMU_CAPS_DRIVE, QEMU_CAPS_DRIVE_COPY_ON_READ,
>              QEMU_CAPS_VIRTIO_TX_ALG, QEMU_CAPS_DEVICE,
>              QEMU_CAPS_VIRTIO_BLK_SCSI, QEMU_CAPS_VIRTIO_BLK_SG_IO);
> +    DO_TEST("disk-drive-discard",
> +            QEMU_CAPS_DRIVE, QEMU_CAPS_DRIVE_DISCARD,
> +            QEMU_CAPS_DEVICE);
>      DO_TEST("disk-snapshot",
>              QEMU_CAPS_DRIVE, QEMU_CAPS_DRIVE_CACHE_V2, QEMU_CAPS_DRIVE_FORMAT);
>      DO_TEST("event_idx",
> diff --git a/tests/qemuxml2xmltest.c b/tests/qemuxml2xmltest.c
> index 492ac60..ffb0e87 100644
> --- a/tests/qemuxml2xmltest.c
> +++ b/tests/qemuxml2xmltest.c
> @@ -259,6 +259,8 @@ mymain(void)
>      DO_TEST("disk-scsi-disk-vpd");
>      DO_TEST("disk-source-pool");
>  
> +    DO_TEST("disk-drive-discard");
> +
>      DO_TEST("virtio-rng-random");
>      DO_TEST("virtio-rng-egd");
>  
> 


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