[Qemu-devel] [PATCH] ISCSI: Pick default initiator-name based on the name of the VM

[Ronnie Sahlberg]

Version 2 based on suggestions from Paolo B.
Use a function 'qemu_get_vm_name()' to pass the -name from qemu to
block/iscsi.c instead of #ifdefs

This patch updates the iscsi layer to automatically pick a
'unique' initiator-name based on the name of the vm in case the user
has not set an explicit iqn-name to use.

Save the -name of the vm so that we can use it in the default iscsi name.

Add a new variable that holds the name for the vm as specified by -name
and assign this name to the iscsi_name pointer gtom block/iscsi.c

This way we can thus create default names to use as the initiator name
based on the guest session.

If -name is not specified, iscsi will use a default initiator-name of
iqn.2008-11.org.linux-kvm

If -name is specified, then iscsi will use a default initiatorname of
iqn.2008-11.org.linux-kvm:<name>

Signed-off-by: Ronnie Sahlberg <address@hidden>
---
 block/iscsi.c   |   14 +++++++++++---
 qemu-common.h   |    1 +
 qemu-doc.texi   |    5 +++++
 qemu-options.hx |    8 ++++++++
 qemu-tool.c     |    5 +++++
 vl.c            |    5 +++++
 6 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/block/iscsi.c b/block/iscsi.c
index 993a86d..243496b 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -896,23 +896,31 @@ static char *parse_initiator_name(const char *target)
     QemuOptsList *list;
     QemuOpts *opts;
     const char *name = NULL;
+    char *default_name;
+    const char *iscsi_name = qemu_get_vm_name();
+
+    if (asprintf(&default_name, "iqn.2008-11.org.linux-kvm%s%s",
+                 iscsi_name ? ":" : "",
+                 iscsi_name ? iscsi_name : "") == -1) {
+        default_name = (char *)"iqn.2008-11.org.linux-kvm";
+    }
 
     list = qemu_find_opts("iscsi");
     if (!list) {
-        return g_strdup("iqn.2008-11.org.linux-kvm");
+        return g_strdup(default_name);
     }
 
     opts = qemu_opts_find(list, target);
     if (opts == NULL) {
         opts = QTAILQ_FIRST(&list->head);
         if (!opts) {
-            return g_strdup("iqn.2008-11.org.linux-kvm");
+            return g_strdup(default_name);
         }
     }
 
     name = qemu_opt_get(opts, "initiator-name");
     if (!name) {
-        return g_strdup("iqn.2008-11.org.linux-kvm");
+        return g_strdup(default_name);
     }
 
     return g_strdup(name);
diff --git a/qemu-common.h b/qemu-common.h
index 7c8dac8..702b410 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -358,6 +358,7 @@ bool buffer_is_zero(const void *buf, size_t len);
 void qemu_progress_init(int enabled, float min_skip);
 void qemu_progress_end(void);
 void qemu_progress_print(float delta, int max);
+const char *qemu_get_vm_name(void);
 
 #define QEMU_FILE_TYPE_BIOS   0
 #define QEMU_FILE_TYPE_KEYMAP 1
diff --git a/qemu-doc.texi b/qemu-doc.texi
index 84dad19..2360f7b 100644
--- a/qemu-doc.texi
+++ b/qemu-doc.texi
@@ -734,6 +734,11 @@ Various session related parameters can be set via special 
options, either
 in a configuration file provided via '-readconfig' or directly on the
 command line.
 
+If the initiator-name is not specified qemu will use a default name
+of 'iqn.2008-11.org.linux-kvm[:<name>'] where <name> is the name of the
+virtual machine.
+
+
 @example
 Setting a specific initiator name to use when logging in to the target
 -iscsi initiator-name=iqn.qemu.test:my-initiator
diff --git a/qemu-options.hx b/qemu-options.hx
index dc68e15..3335bcc 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1893,6 +1893,11 @@ images for the guest storage. Both disk and cdrom images 
are supported.
 Syntax for specifying iSCSI LUNs is
 ``iscsi://<target-ip>[:<port>]/<target-iqn>/<lun>''
 
+By default qemu will use the iSCSI initiator-name
+'iqn.2008-11.org.linux-kvm[:<name>]' but this can also be set from the command
+line or a configuration file.
+
+
 Example (without authentication):
 @example
 qemu-system-i386 -iscsi initiator-name=iqn.2001-04.com.example:my-initiator \
@@ -1922,6 +1927,9 @@ DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi,
     "                iSCSI session parameters\n", QEMU_ARCH_ALL)
 STEXI
 
+iSCSI parameters such as username and password can also be specified via
+a configuration file. See qemu-doc for more information and examples.
+
 @item NBD
 QEMU supports NBD (Network Block Devices) both using TCP protocol as well
 as Unix Domain Sockets.
diff --git a/qemu-tool.c b/qemu-tool.c
index 318c5fc..64b5e88 100644
--- a/qemu-tool.c
+++ b/qemu-tool.c
@@ -30,6 +30,11 @@ struct QEMUBH
     void *opaque;
 };
 
+const char *qemu_get_vm_name(void)
+{
+    return NULL;
+}
+
 Monitor *cur_mon;
 
 int monitor_cur_is_qmp(void)
diff --git a/vl.c b/vl.c
index 8904db1..dd5716c 100644
--- a/vl.c
+++ b/vl.c
@@ -291,6 +291,11 @@ static struct {
     { .driver = "qxl-vga",              .flag = &default_vga       },
 };
 
+const char *qemu_get_vm_name(void)
+{
+    return qemu_name;
+}
+
 static void res_free(void)
 {
     if (boot_splash_filedata != NULL) {
-- 
1.7.3.1