[V3,05/24,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..3e5f4c7
--- /dev/null
+++ b/hw/9pfs/cofs.c
@@ -0,0 +1,43 @@ 
+
+/*
+ * 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"
+
+int v9fs_co_readlink(V9fsState *s, V9fsString *path, V9fsString *buf)
+{
+    int err;
+    ssize_t len;
+    V9fsString tbuf;
+
+    v9fs_string_init(&tbuf);
+    tbuf.data = qemu_malloc(PATH_MAX);
+    v9fs_co_run_in_worker(
+        {
+            len = s->ops->readlink(&s->ctx, path->data,
+                                   tbuf.data, PATH_MAX - 1);
+            if (len > -1) {
+                tbuf.size = len;
+                tbuf.data[len] = 0;
+                err = 0;
+            } else {
+                err = -errno;
+            }
+        });
+    buf->size = tbuf.size;
+    buf->data = tbuf.data;
+    return err;
+}
diff --git a/hw/9pfs/virtio-9p-coth.h b/hw/9pfs/virtio-9p-coth.h
index 9388f9b..94c5147 100644
--- a/hw/9pfs/virtio-9p-coth.h
+++ b/hw/9pfs/virtio-9p-coth.h
@@ -56,4 +56,5 @@  typedef struct V9fsThPool {
 
 extern void co_run_in_worker_bh(void *);
 extern int v9fs_init_worker_threads(void);
+extern int v9fs_co_readlink(V9fsState *, V9fsString *, V9fsString *);
 #endif
diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c
index 4efbbca..3e0d933 100644
--- a/hw/9pfs/virtio-9p.c
+++ b/hw/9pfs/virtio-9p.c
@@ -82,21 +82,6 @@  static int v9fs_do_lstat(V9fsState *s, V9fsString *path, struct stat *stbuf)
     return s->ops->lstat(&s->ctx, path->data, stbuf);
 }
 
-static ssize_t v9fs_do_readlink(V9fsState *s, V9fsString *path, V9fsString *buf)
-{
-    ssize_t len;
-
-    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;
-    }
-
-    return len;
-}
-
 static int v9fs_do_close(V9fsState *s, int fd)
 {
     return s->ops->close(&s->ctx, fd);
@@ -291,7 +276,7 @@  static int v9fs_do_lremovexattr(V9fsState *s, V9fsString *path,
 }
 
 
-static void v9fs_string_init(V9fsString *str)
+void v9fs_string_init(V9fsString *str)
 {
     str->data = NULL;
     str->size = 0;
@@ -1055,13 +1040,10 @@  static int stat_to_v9stat(V9fsState *s, V9fsString *name,
     v9fs_string_null(&v9stat->extension);
 
     if (v9stat->mode & P9_STAT_MODE_SYMLINK) {
-        err = v9fs_do_readlink(s, name, &v9stat->extension);
-        if (err == -1) {
-            err = -errno;
+        err = v9fs_co_readlink(s, name, &v9stat->extension);
+        if (err < 0) {
             return err;
         }
-        v9stat->extension.data[err] = 0;
-        v9stat->extension.size = err;
     } else if (v9stat->mode & P9_STAT_MODE_DEVICE) {
         v9fs_string_sprintf(&v9stat->extension, "%c %u %u",
                 S_ISCHR(stbuf->st_mode) ? 'c' : 'b',
@@ -3600,9 +3582,8 @@  static void v9fs_readlink(void *opaque)
     }
 
     v9fs_string_init(&target);
-    err = v9fs_do_readlink(pdu->s, &fidp->path, &target);
+    err = v9fs_co_readlink(pdu->s, &fidp->path, &target);
     if (err < 0) {
-        err = -errno;
         goto out;
     }
     offset += pdu_marshal(pdu, offset, "s", &target);
diff --git a/hw/9pfs/virtio-9p.h b/hw/9pfs/virtio-9p.h
index e95b63d..78d45b5 100644
--- a/hw/9pfs/virtio-9p.h
+++ b/hw/9pfs/virtio-9p.h
@@ -505,5 +505,5 @@  static inline size_t do_pdu_unpack(void *dst, struct iovec *sg, int sg_count,
 }
 
 extern void handle_9p_output(VirtIODevice *vdev, VirtQueue *vq);
-
+void v9fs_string_init(V9fsString *str);
 #endif