[Qemu-devel] [PATCH 5/6] This patch converts v9fs_open() to make use of the threadlets infrastructure.

[Arun R Bharadwaj <arun@linux.vnet.ibm.com>]

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

This patch offloads all the blocking calls invoked for v9fs_open onto the
helper threads belonging to the threadlets infrastructure. The handling of
the v9fs_post_*open* calls is done from the io-thread context.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
---
 hw/virtio-9p.c |   86 +++++++++++++++++++++++++++++++++++++++++---------------
 hw/virtio-9p.h |    5 +++
 2 files changed, 68 insertions(+), 23 deletions(-)

diff --git a/hw/virtio-9p.c b/hw/virtio-9p.c
index 5fb7dc4..75d4be3 100644
--- a/hw/virtio-9p.c
+++ b/hw/virtio-9p.c
@@ -1777,6 +1777,41 @@ out:
     v9fs_walk_complete(s, vs, err);
 }
 
+/********************* v9fs_open calls *********************************/
+static void v9fs_open_do_lstat(ThreadletWork *work)
+{
+    V9fsOpenState *vs;
+
+    vs = container_of(work, V9fsOpenState, work);
+    vs->err = v9fs_do_lstat(vs->s, &vs->fidp->path, &vs->stbuf);
+    vs->v9fs_errno = errno;
+
+    v9fs_async_helper_done(vs->post_fn, vs);
+}
+
+static void v9fs_open_do_opendir(ThreadletWork *work)
+{
+    V9fsOpenState *vs;
+
+    vs = container_of(work, V9fsOpenState, work);
+    vs->fidp->fs.dir = v9fs_do_opendir(vs->s, &vs->fidp->path);
+    vs->v9fs_errno = errno;
+
+    v9fs_async_helper_done(vs->post_fn, vs);
+}
+
+static void v9fs_open_do_open(ThreadletWork *work)
+{
+    V9fsOpenState *vs;
+
+    vs = container_of(work, V9fsOpenState, work);
+    vs->fidp->fs.fd = v9fs_do_open(vs->s, &vs->fidp->path,
+                                omode_to_uflags(vs->mode));
+    vs->v9fs_errno = errno;
+
+    v9fs_async_helper_done(vs->post_fn, vs);
+}
+
 static int32_t get_iounit(V9fsState *s, V9fsString *name)
 {
     struct statfs stbuf;
@@ -1797,17 +1832,19 @@ static int32_t get_iounit(V9fsState *s, V9fsString *name)
     return iounit;
 }
 
-static void v9fs_open_post_opendir(V9fsState *s, V9fsOpenState *vs, int err)
+static void v9fs_open_post_opendir(void *opaque)
 {
+    V9fsOpenState *vs = (V9fsOpenState *)opaque;
+
     if (vs->fidp->fs.dir == NULL) {
-        err = -errno;
+        vs->err = -errno;
         goto out;
     }
     vs->fidp->fid_type = P9_FID_DIR;
     vs->offset += pdu_marshal(vs->pdu, vs->offset, "Qd", &vs->qid, 0);
-    err = vs->offset;
+    vs->err = vs->offset;
 out:
-    complete_pdu(s, vs->pdu, err);
+    complete_pdu(vs->s, vs->pdu, vs->err);
     qemu_free(vs);
 
 }
@@ -1821,35 +1858,39 @@ static void v9fs_open_post_getiounit(V9fsState *s, V9fsOpenState *vs)
     qemu_free(vs);
 }
 
-static void v9fs_open_post_open(V9fsState *s, V9fsOpenState *vs, int err)
+static void v9fs_open_post_open(void *opaque)
 {
+    V9fsOpenState *vs = (V9fsOpenState *)opaque;
+
     if (vs->fidp->fs.fd == -1) {
-        err = -errno;
+        vs->err = -errno;
         goto out;
     }
     vs->fidp->fid_type = P9_FID_FILE;
-    vs->iounit = get_iounit(s, &vs->fidp->path);
-    v9fs_open_post_getiounit(s, vs);
+    /* FIXME: Need a new state here */
+    vs->iounit = get_iounit(vs->s, &vs->fidp->path);
+    v9fs_open_post_getiounit(vs->s, vs);
     return;
 out:
-    complete_pdu(s, vs->pdu, err);
+    complete_pdu(vs->s, vs->pdu, vs->err);
     qemu_free(vs);
 }
 
-static void v9fs_open_post_lstat(V9fsState *s, V9fsOpenState *vs, int err)
+static void v9fs_open_post_lstat(void *opaque)
 {
+    V9fsOpenState *vs = (V9fsOpenState *)opaque;
     int flags;
 
-    if (err) {
-        err = -errno;
+    if (vs->err) {
+        vs->err = -errno;
         goto out;
     }
 
     stat_to_qid(&vs->stbuf, &vs->qid);
 
     if (S_ISDIR(vs->stbuf.st_mode)) {
-        vs->fidp->fs.dir = v9fs_do_opendir(s, &vs->fidp->path);
-        v9fs_open_post_opendir(s, vs, err);
+        v9fs_do_async_posix(&vs->work, v9fs_open_do_opendir, &vs->post_fn,
+                            v9fs_open_post_opendir);
     } else {
         if (s->proto_version == V9FS_PROTO_2000L) {
             flags = vs->mode;
@@ -1859,12 +1900,12 @@ static void v9fs_open_post_lstat(V9fsState *s, V9fsOpenState *vs, int err)
         } else {
             flags = omode_to_uflags(vs->mode);
         }
-        vs->fidp->fs.fd = v9fs_do_open(s, &vs->fidp->path, flags);
-        v9fs_open_post_open(s, vs, err);
+        v9fs_do_async_posix(&vs->work, v9fs_open_do_open, &vs->post_fn,
+                             v9fs_open_post_open);
     }
     return;
 out:
-    complete_pdu(s, vs->pdu, err);
+    complete_pdu(vs->s, vs->pdu, vs->err);
     qemu_free(vs);
 }
 
@@ -1872,12 +1913,12 @@ static void v9fs_open(V9fsState *s, V9fsPDU *pdu)
 {
     int32_t fid;
     V9fsOpenState *vs;
-    ssize_t err = 0;
 
     vs = qemu_malloc(sizeof(*vs));
     vs->pdu = pdu;
     vs->offset = 7;
     vs->mode = 0;
+    vs->s = s;
 
     if (s->proto_version == V9FS_PROTO_2000L) {
         pdu_unmarshal(vs->pdu, vs->offset, "dd", &fid, &vs->mode);
@@ -1887,18 +1928,17 @@ static void v9fs_open(V9fsState *s, V9fsPDU *pdu)
 
     vs->fidp = lookup_fid(s, fid);
     if (vs->fidp == NULL) {
-        err = -ENOENT;
+        vs->err = -ENOENT;
         goto out;
     }
 
     BUG_ON(vs->fidp->fid_type != P9_FID_NONE);
 
-    err = v9fs_do_lstat(s, &vs->fidp->path, &vs->stbuf);
-
-    v9fs_open_post_lstat(s, vs, err);
+    v9fs_do_async_posix(&vs->work, v9fs_open_do_lstat, &vs->post_fn,
+                        v9fs_open_post_lstat);
     return;
 out:
-    complete_pdu(s, pdu, err);
+    complete_pdu(vs->s, pdu, vs->err);
     qemu_free(vs);
 }
 
diff --git a/hw/virtio-9p.h b/hw/virtio-9p.h
index be87d5f..294de83 100644
--- a/hw/virtio-9p.h
+++ b/hw/virtio-9p.h
@@ -306,6 +306,11 @@ typedef struct V9fsOpenState {
     V9fsQID qid;
     struct stat stbuf;
     int iounit;
+    V9fsState *s;
+    int err;
+    int v9fs_errno;
+    ThreadletWork work;
+    void (*post_fn)(void *arg);
 } V9fsOpenState;
 
 typedef struct V9fsReadState {