[Qemu-devel] [PATCH -V3 30/32] virtio-9p: Create a syntactic shortcut for the file-system pass-thru

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

From: Gautham R Shenoy <ego@in.ibm.com>

Currently the commandline to create a virtual-filesystem pass-through between
the guest and the host is as follows:
#qemu -fsdev fstype,id=ID,path=path/to/share \
      -device virtio-9p-pci,fsdev=ID,mount_tag=tag \

This patch provides a syntactic short-cut to achieve the same as follows:
#qemu -virtfs fstype,path=path/to/share,mount_tag=tag

This will be internally expanded as:
#qemu -fsdev fstype,id=tag,path=path/to/share, \
      -device virtio-9p-pci,fsdev=tag,mount_tag=tag \

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 qemu-config.c   |   20 ++++++++++++++++++++
 qemu-config.h   |    1 +
 qemu-options.hx |   32 ++++++++++++++++++++++++++++++++
 vl.c            |   42 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 95 insertions(+), 0 deletions(-)

diff --git a/qemu-config.c b/qemu-config.c
index 0c06e1b..5564a24 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -167,6 +167,26 @@ QemuOptsList qemu_fsdev_opts = {
     },
 };
 
+QemuOptsList qemu_virtfs_opts = {
+    .name = "virtfs",
+    .implied_opt_name = "fstype",
+    .head = QTAILQ_HEAD_INITIALIZER(qemu_virtfs_opts.head),
+    .desc = {
+        {
+            .name = "fstype",
+            .type = QEMU_OPT_STRING,
+        },{
+            .name = "path",
+            .type = QEMU_OPT_STRING,
+        },{
+            .name = "mount_tag",
+            .type = QEMU_OPT_STRING,
+        },
+
+        { /*End of list */ }
+    },
+};
+
 QemuOptsList qemu_device_opts = {
     .name = "device",
     .implied_opt_name = "driver",
diff --git a/qemu-config.h b/qemu-config.h
index b01306c..8612747 100644
--- a/qemu-config.h
+++ b/qemu-config.h
@@ -4,6 +4,7 @@
 extern QemuOptsList qemu_drive_opts;
 extern QemuOptsList qemu_chardev_opts;
 extern QemuOptsList qemu_fsdev_opts;
+extern QemuOptsList qemu_virtfs_opts;
 extern QemuOptsList qemu_device_opts;
 extern QemuOptsList qemu_netdev_opts;
 extern QemuOptsList qemu_net_opts;
diff --git a/qemu-options.hx b/qemu-options.hx
index 71a6fda..cbdc22b 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -498,6 +498,38 @@ Create a file-system-"device" for local-filesystem.
 @end table
 ETEXI
 
+DEFHEADING(Virtual File system pass-through options:)
+
+DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs,
+    "-virtfs local,path=path,mount_tag=tag\n")
+
+STEXI
+
+The general form of a Virtual File system pass-through option is:
+@table @option
+
+@item -virtfs @var{fstype} [,@var{options}]
+@findex -virtfs
+Fstype is one of:
+@option{local},
+The specific Fstype will determine the applicable options.
+
+Options to each backend are described below.
+
+@item -virtfs local ,path=@var{path} ,mount_tag=@var{mount_tag}
+
+Create a Virtual file-system-pass through for local-filesystem.
+
+@option{local} is only available on Linux.
+
+@option{path} specifies the path to be exported. @option{path} is required.
+
+@option{mount_tag} specifies the tag with which the exported file is mounted.
+@option{mount_tag} is required.
+
+@end table
+ETEXI
+
 DEFHEADING()
 
 DEF("name", HAS_ARG, QEMU_OPTION_name,
diff --git a/vl.c b/vl.c
index 0228045..e9e597b 100644
--- a/vl.c
+++ b/vl.c
@@ -3747,6 +3747,8 @@ int main(int argc, char **argv, char **envp)
     CPUState *env;
     int show_vnc_port = 0;
     int defconfig = 1;
+    char *arg_fsdev = NULL;
+    char *arg_9p = NULL;
 
     error_set_progname(argv[0]);
 
@@ -4272,6 +4274,46 @@ int main(int argc, char **argv, char **envp)
                     exit(1);
                 }
                 break;
+            case QEMU_OPTION_virtfs:
+                opts = qemu_opts_parse(&qemu_virtfs_opts, optarg, 1);
+                if (!opts) {
+                    fprintf(stderr, "parse error: %s\n", optarg);
+                    exit(1);
+                }
+
+                qemu_asprintf(&arg_fsdev, "%s,id=%s,path=%s",
+                                qemu_opt_get(opts, "fstype"),
+                                qemu_opt_get(opts, "mount_tag"),
+                                qemu_opt_get(opts, "path"));
+                if (!arg_fsdev) {
+                    fprintf(stderr, "No memory to parse -fsdev for %s\n",
+                            optarg);
+                    exit(1);
+                }
+
+
+                qemu_asprintf(&arg_9p, "virtio-9p-pci,fsdev=%s,mount_tag=%s",
+                                qemu_opt_get(opts, "mount_tag"),
+                                qemu_opt_get(opts, "mount_tag"));
+                if (!arg_9p) {
+                    fprintf(stderr, "No memory to parse -device for %s\n",
+                            optarg);
+                    exit(1);
+                }
+
+                if (!qemu_opts_parse(&qemu_fsdev_opts, arg_fsdev, 1)) {
+                    fprintf(stderr, "parse error [fsdev]: %s\n", optarg);
+                    exit(1);
+                }
+
+                if (!qemu_opts_parse(&qemu_device_opts, arg_9p, 1)) {
+                    fprintf(stderr, "parse error [device]: %s\n", optarg);
+                    exit(1);
+                }
+
+                qemu_free(arg_fsdev);
+                qemu_free(arg_9p);
+                break;
             case QEMU_OPTION_serial:
                 add_device_config(DEV_SERIAL, optarg);
                 default_serial = 0;
-- 
1.7.0.2.323.g0d092