[06/25,virtio-9p] coroutines for readlink

diff --git a/Makefile.objs b/Makefile.objs
index 96f6a24..36005bb 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -297,7 +297,7 @@  hw-obj-$(CONFIG_SOUND) += $(sound-obj-y)
 9pfs-nested-$(CONFIG_VIRTFS) = virtio-9p.o virtio-9p-debug.o
 9pfs-nested-$(CONFIG_VIRTFS) +=  virtio-9p-local.o virtio-9p-xattr.o
 9pfs-nested-$(CONFIG_VIRTFS) +=   virtio-9p-xattr-user.o virtio-9p-posix-acl.o
-9pfs-nested-$(CONFIG_VIRTFS) += virtio-9p-coth.o
+9pfs-nested-$(CONFIG_VIRTFS) += virtio-9p-coth.o cofs.o
 
 hw-obj-$(CONFIG_REALLY_VIRTFS) += $(addprefix 9pfs/, $(9pfs-nested-y))
 $(addprefix 9pfs/, $(9pfs-nested-y)): QEMU_CFLAGS+=$(GLIB_CFLAGS)
diff --git a/hw/9pfs/cofs.c b/hw/9pfs/cofs.c
new file mode 100644
index 0000000..b972561
--- /dev/null
+++ b/hw/9pfs/cofs.c
@@ -0,0 +1,60 @@ 
+
+/*
+ * Virtio 9p backend
+ *
+ * Copyright IBM, Corp. 2011
+ *
+ * Authors:
+ *  Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include "fsdev/qemu-fsdev.h"
+#include "qemu-thread.h"
+#include "qemu-coroutine.h"
+#include "virtio-9p-coth.h"
+
+typedef struct V9fsThReadlinkState {
+    V9fsState *s;
+    V9fsString *path;
+    V9fsString *buf;
+    ssize_t len;
+    int err;
+    V9fsRequest request;
+} V9fsThReadlinkState;
+
+static void v9fs_th_do_readlink(V9fsRequest *request)
+{
+    V9fsThReadlinkState *vsp = container_of(request, V9fsThReadlinkState,
+            request);
+    vsp->buf->data = qemu_malloc(PATH_MAX);
+
+    vsp->len = vsp->s->ops->readlink(&vsp->s->ctx, vsp->path->data,
+                                     vsp->buf->data, PATH_MAX - 1);
+    if (vsp->len > -1) {
+        vsp->buf->size = vsp->len;
+        vsp->buf->data[vsp->len] = 0;
+        vsp->err = 0;
+    } else {
+        vsp->err = -errno;
+    }
+}
+
+int v9fs_co_readlink(V9fsState *s, V9fsString *path, V9fsString *buf,
+        ssize_t *len)
+{
+    V9fsThReadlinkState vs;
+    vs.s = s;
+    vs.path = path;
+    vs.buf = buf;
+    vs.request.func = v9fs_th_do_readlink;
+    vs.request.coroutine = qemu_coroutine_self();
+    v9fs_qemu_submit_request(&vs.request);
+    qemu_coroutine_yield();
+    buf->size = vs.buf->size;
+    buf->data = vs.buf->data;
+    return vs.err;
+}
diff --git a/hw/9pfs/virtio-9p-coth.h b/hw/9pfs/virtio-9p-coth.h
index 2ec1401..d0b856e 100644
--- a/hw/9pfs/virtio-9p-coth.h
+++ b/hw/9pfs/virtio-9p-coth.h
@@ -48,5 +48,6 @@  extern void v9fs_thread_routine(gpointer data, gpointer user_data);
 extern void v9fs_qemu_process_req_done(void *arg);
 extern void v9fs_qemu_submit_request(V9fsRequest *req);
 
-
+extern int v9fs_co_readlink(V9fsState *, V9fsString *,
+                            V9fsString *, ssize_t *);
 #endif
diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c
index a748c34..7ef6ad8 100644
--- a/hw/9pfs/virtio-9p.c
+++ b/hw/9pfs/virtio-9p.c
@@ -82,23 +82,6 @@  static int v9fs_do_lstat(V9fsState *s, V9fsString *path, struct stat *stbuf)
     return s->ops->lstat(&s->ctx, path->data, stbuf);
 }
 
-static int v9fs_do_readlink(V9fsState *s, V9fsString *path, V9fsString *buf,
-        ssize_t *len)
-{
-    int err;
-    buf->data = qemu_malloc(1024);
-
-    *len = s->ops->readlink(&s->ctx, path->data, buf->data, 1024 - 1);
-    if (*len > -1) {
-        buf->size = *len;
-        buf->data[*len] = 0;
-        err = 0;
-    } else {
-        err = -errno;
-    }
-    return err;
-}
-
 static int v9fs_do_close(V9fsState *s, int fd)
 {
     return s->ops->close(&s->ctx, fd);
@@ -1058,7 +1041,7 @@  static int stat_to_v9stat(V9fsState *s, V9fsString *name,
 
     if (v9stat->mode & P9_STAT_MODE_SYMLINK) {
         ssize_t symlink_len;
-        err = v9fs_do_readlink(s, name, &v9stat->extension, &symlink_len);
+        err = v9fs_co_readlink(s, name, &v9stat->extension, &symlink_len);
         if (err < 0) {
             return err;
         }
@@ -3655,10 +3638,11 @@  static void v9fs_readlink(void *opaque)
     }
 
     v9fs_string_init(&target);
-    err = v9fs_do_readlink(copdu->s, &fidp->path, &target, &symlink_len);
+    err = v9fs_co_readlink(copdu->s, &fidp->path, &target, &symlink_len);
     if (err < 0) {
         goto out;
     }
+
     offset += pdu_marshal(copdu->pdu, offset, "s", &target);
     err = offset;
     v9fs_string_free(&target);