qemu: add support for libiscsi

libiscsi provides a userspace iSCSI initiator.

The main advantage over the kernel initiator is that it is very
easy to provide different initiator names for VMs on the same host.
Thus libiscsi supports usage of persistent reservations in the VM,
which otherwise would only be possible with NPIV.

libiscsi uses "iscsi" as the scheme, not "iscsi+tcp".  We can change
this in the tests (while remaining backwards-compatible manner, because
QEMU uses TCP as the default transport for both Gluster and NBD).
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

docs/formatdomain.html.in

@@ -1446,10 +1446,13 @@
         are "nbd", "iscsi", "rbd", "sheepdog" or "gluster".  If the
         <code>protocol</code> attribute is "rbd", "sheepdog" or "gluster", an
         additional attribute <code>name</code> is mandatory to specify which
-        volume/image will be used; for "nbd" it is optional.  When the disk
-        <code>type</code> is "network", the <code>source</code> may have zero
-        or more <code>host</code> sub-elements used to specify the hosts
-        to connect.
+        volume/image will be used; for "nbd" it is optional.  For "iscsi",
+        the <code>name</code> attribute may include a logical unit number,
+        separated from the target's name by a slash (for example,
+        <code>iqn.1992-01.com.example/1</code>); the default LUN is zero.
+        When the disk <code>type</code> is "network", the <code>source</code>
+        may have zero or more <code>host</code> sub-elements used to
+        specify the hosts to connect.
         <span class="since">Since 0.0.3; <code>type='dir'</code> since
         0.7.5; <code>type='network'</code> since
         0.8.7; <code>protocol='iscsi'</code> since 1.0.4</span><br/>

src/qemu/qemu_command.c

@@ -2390,6 +2390,31 @@ qemuParseGlusterString(virDomainDiskDefPtr def)
     return qemuParseDriveURIString(def, uri, "gluster");
 }
 
+static int
+qemuParseISCSIString(virDomainDiskDefPtr def)
+{
+    virURIPtr uri = NULL;
+    char *slash;
+    unsigned lun;
+
+    if (!(uri = virURIParse(def->src)))
+        return -1;
+
+    if (uri->path &&
+        (slash = strchr(uri->path + 1, '/')) != NULL) {
+
+        if (slash[1] == '\0')
+            *slash = '\0';
+        else if (virStrToLong_ui(slash + 1, NULL, 10, &lun) == -1) {
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("invalid name '%s' for iSCSI disk"), def->src);
+            return -1;
+        }
+    }
+
+    return qemuParseDriveURIString(def, uri, "iscsi");
+}
+
 static int
 qemuParseNBDString(virDomainDiskDefPtr disk)
 {
@@ -2484,8 +2509,14 @@ qemuBuildDriveURIString(virDomainDiskDefPtr disk, virBufferPtr opt,
     virBufferAddLit(opt, "file=");
     transp = virDomainDiskProtocolTransportTypeToString(disk->hosts->transport);
 
-    if (virAsprintf(&tmpscheme, "%s+%s", scheme, transp) < 0)
-        goto no_memory;
+    if (disk->hosts->transport == VIR_DOMAIN_DISK_PROTO_TRANS_TCP) {
+        tmpscheme = strdup(scheme);
+        if (tmpscheme == NULL)
+            goto no_memory;
+    } else {
+        if (virAsprintf(&tmpscheme, "%s+%s", scheme, transp) < 0)
+            goto no_memory;
+    }
 
     if (disk->src && virAsprintf(&volimg, "/%s", disk->src) < 0)
         goto no_memory;
@@ -2530,6 +2561,12 @@ qemuBuildGlusterString(virDomainDiskDefPtr disk, virBufferPtr opt)
 
 #define QEMU_DEFAULT_NBD_PORT "10809"
 
+static int
+qemuBuildISCSIString(virDomainDiskDefPtr disk, virBufferPtr opt)
+{
+    return qemuBuildDriveURIString(disk, opt, "iscsi");
+}
+
 static int
 qemuBuildNBDString(virDomainDiskDefPtr disk, virBufferPtr opt)
 {
@@ -2713,6 +2750,11 @@ qemuBuildDriveStr(virConnectPtr conn ATTRIBUTE_UNUSED,
                     goto error;
                 virBufferAddChar(&opt, ',');
                 break;
+            case VIR_DOMAIN_DISK_PROTOCOL_ISCSI:
+                if (qemuBuildISCSIString(disk, &opt) < 0)
+                    goto error;
+                virBufferAddChar(&opt, ',');
+                break;
 
             case VIR_DOMAIN_DISK_PROTOCOL_SHEEPDOG:
                 if (disk->nhosts == 0) {
@@ -7909,6 +7951,12 @@ qemuParseCommandLineDisk(virCapsPtr qemuCaps,
 
                     if (qemuParseGlusterString(def) < 0)
                         goto error;
+                } else if (STRPREFIX(def->src, "iscsi:")) {
+                    def->type = VIR_DOMAIN_DISK_TYPE_NETWORK;
+                    def->protocol = VIR_DOMAIN_DISK_PROTOCOL_ISCSI;
+
+                    if (qemuParseISCSIString(def) < 0)
+                        goto error;
                 } else if (STRPREFIX(def->src, "sheepdog:")) {
                     char *p = def->src;
                     char *port, *vdi;
@@ -9199,6 +9247,11 @@ virDomainDefPtr qemuParseCommandLine(virCapsPtr qemuCaps,
                     if (qemuParseGlusterString(disk) < 0)
                         goto error;
 
+                    break;
+                case VIR_DOMAIN_DISK_PROTOCOL_ISCSI:
+                    if (qemuParseISCSIString(disk) < 0)
+                        goto error;
+
                     break;
                 }
             }

tests/qemuargv2xmltest.c

@@ -189,6 +189,7 @@ mymain(void)
     DO_TEST("disk-drive-network-nbd-ipv6");
     DO_TEST("disk-drive-network-nbd-ipv6-export");
     DO_TEST("disk-drive-network-nbd-unix");
+    DO_TEST("disk-drive-network-iscsi");
     DO_TEST("disk-drive-network-gluster");
     DO_TEST("disk-drive-network-rbd");
     DO_TEST("disk-drive-network-rbd-ipv6");

tests/qemuxml2argvdata/qemuxml2argv-disk-drive-network-gluster.args

-LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu -S -M pc -m 214 -smp 1 -nographic -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -usb -drive file=gluster+tcp://example.org:6000/Volume1/Image,if=virtio,format=raw -drive 'file=gluster+unix:///Volume2/Image?socket=/path/to/sock,if=virtio,format=raw' -net none -serial none -parallel none
+LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu -S -M pc -m 214 -smp 1 -nographic -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -usb -drive file=gluster://example.org:6000/Volume1/Image,if=virtio,format=raw -drive 'file=gluster+unix:///Volume2/Image?socket=/path/to/sock,if=virtio,format=raw' -net none -serial none -parallel none

tests/qemuxml2argvdata/qemuxml2argv-disk-drive-network-iscsi.args

+LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu -S -M pc -m 214 -smp 1 -nographic -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -usb -drive file=iscsi://example.org:6000/iqn.1992-01.com.example,if=virtio,format=raw -drive file=iscsi://example.org:6000/iqn.1992-01.com.example/1,if=virtio,format=raw -net none -serial none -parallel none

tests/qemuxml2argvdata/qemuxml2argv-disk-drive-network-iscsi.xml

@@ -21,6 +21,13 @@
       </source>
       <target dev='vda' bus='virtio'/>
     </disk>
+    <disk type='network' device='disk'>
+      <driver name='qemu' type='raw'/>
+      <source protocol='iscsi' name='iqn.1992-01.com.example/1'>
+        <host name='example.org' port='6000'/>
+      </source>
+      <target dev='vdb' bus='virtio'/>
+    </disk>
     <controller type='usb' index='0'/>
     <memballoon model='virtio'/>
   </devices>

tests/qemuxml2argvdata/qemuxml2argv-disk-drive-network-nbd-ipv6-export.args

 LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu -S -M \
 pc -m 214 -smp 1 -nographic -monitor unix:/tmp/test-monitor,server,nowait \
 -no-acpi -boot c -usb -drive file=/dev/HostVG/QEMUGuest1,if=ide,bus=0,unit=0 \
--drive 'file=nbd+tcp://[::1]:6000/bar,if=virtio,format=raw' -net none \
+-drive 'file=nbd://[::1]:6000/bar,if=virtio,format=raw' -net none \
 -serial none -parallel none

tests/qemuxml2argvdata/qemuxml2argv-disk-drive-network-nbd-ipv6.args

 LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu -S -M \
 pc -m 214 -smp 1 -nographic -monitor unix:/tmp/test-monitor,server,nowait \
 -no-acpi -boot c -usb -drive file=/dev/HostVG/QEMUGuest1,if=ide,bus=0,unit=0 \
--drive 'file=nbd+tcp://[::1]:6000,if=virtio,format=raw' -net none \
+-drive 'file=nbd://[::1]:6000,if=virtio,format=raw' -net none \
 -serial none -parallel none

tests/qemuxml2argvtest.c

@@ -501,6 +501,8 @@ mymain(void)
             QEMU_CAPS_DRIVE, QEMU_CAPS_DRIVE_FORMAT);
     DO_TEST("disk-drive-network-nbd-unix",
             QEMU_CAPS_DRIVE, QEMU_CAPS_DRIVE_FORMAT);
+    DO_TEST("disk-drive-network-iscsi",
+            QEMU_CAPS_DRIVE, QEMU_CAPS_DRIVE_FORMAT);
     DO_TEST("disk-drive-network-gluster",
             QEMU_CAPS_DRIVE, QEMU_CAPS_DRIVE_FORMAT);
     DO_TEST("disk-drive-network-rbd",