Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

Block pull request

# gpg: Signature made Thu 13 Mar 2014 13:50:49 GMT using RSA key ID 81AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/block-pull-request: (24 commits)
  block/raw-win32: bdrv_parse_filename() for hdev
  block/raw-posix: Strip protocol prefix on creation
  block/raw-posix: bdrv_parse_filename() for cdrom
  block/raw-posix: bdrv_parse_filename() for floppy
  block/raw-posix: bdrv_parse_filename() for hdev
  qemu-io: Fix warnings from static code analysis
  block: Unlink temporary file
  qcow2: Don't write with BDRV_O_INCOMING
  qcow2: Keep option in qcow2_invalidate_cache()
  qmp: add query-iothreads command
  iothread: stash thread ID away
  dataplane: replace internal thread with IOThread
  iothread: add "iothread" qdev property type
  qdev: make get_pointer() handle temporary strings
  iothread: add I/O thread object
  aio: add aio_context_acquire() and aio_context_release()
  rfifolock: add recursive FIFO lock
  object: add object_get_canonical_path_component()
  block: Rewrite the snapshot authorization mechanism for block filters.
  iotests: Test corruption during COW request
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 54 insertions, 42 deletions

diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index d1c7ad4574..a5afc217c0 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -23,6 +23,7 @@
 #include "virtio-blk.h"
 #include "block/aio.h"
 #include "hw/virtio/virtio-bus.h"
+#include "monitor/monitor.h" /* for object_add() */
 
 enum {
     SEG_MAX = 126,                  /* maximum number of I/O segments */
@@ -44,8 +45,6 @@ struct VirtIOBlockDataPlane {
     bool started;
     bool starting;
     bool stopping;
-    QEMUBH *start_bh;
-    QemuThread thread;
 
     VirtIOBlkConf *blk;
     int fd;                         /* image file descriptor */
@@ -59,12 +58,14 @@ struct VirtIOBlockDataPlane {
      * (because you don't own the file descriptor or handle; you just
      * use it).
      */
+    IOThread *iothread;
+    bool internal_iothread;
     AioContext *ctx;
     EventNotifier io_notifier;      /* Linux AIO completion */
     EventNotifier host_notifier;    /* doorbell */
 
     IOQueue ioqueue;                /* Linux AIO queue (should really be per
-                                       dataplane thread) */
+                                       IOThread) */
     VirtIOBlockRequest requests[REQ_MAX]; /* pool of requests, managed by the
                                              queue */
 
@@ -342,26 +343,7 @@ static void handle_io(EventNotifier *e)
     }
 }
 
-static void *data_plane_thread(void *opaque)
-{
-    VirtIOBlockDataPlane *s = opaque;
-
-    while (!s->stopping || s->num_reqs > 0) {
-        aio_poll(s->ctx, true);
-    }
-    return NULL;
-}
-
-static void start_data_plane_bh(void *opaque)
-{
-    VirtIOBlockDataPlane *s = opaque;
-
-    qemu_bh_delete(s->start_bh);
-    s->start_bh = NULL;
-    qemu_thread_create(&s->thread, "data_plane", data_plane_thread,
-                       s, QEMU_THREAD_JOINABLE);
-}
-
+/* Context: QEMU global mutex held */
 void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,
                                   VirtIOBlockDataPlane **dataplane,
                                   Error **errp)
@@ -408,12 +390,33 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *blk,
     s->fd = fd;
     s->blk = blk;
 
+    if (blk->iothread) {
+        s->internal_iothread = false;
+        s->iothread = blk->iothread;
+        object_ref(OBJECT(s->iothread));
+    } else {
+        /* Create per-device IOThread if none specified */
+        Error *local_err = NULL;
+
+        s->internal_iothread = true;
+        object_add(TYPE_IOTHREAD, vdev->name, NULL, NULL, &local_err);
+        if (error_is_set(&local_err)) {
+            error_propagate(errp, local_err);
+            g_free(s);
+            return;
+        }
+        s->iothread = iothread_find(vdev->name);
+        assert(s->iothread);
+    }
+    s->ctx = iothread_get_aio_context(s->iothread);
+
     /* Prevent block operations that conflict with data plane thread */
     bdrv_set_in_use(blk->conf.bs, 1);
 
     *dataplane = s;
 }
 
+/* Context: QEMU global mutex held */
 void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
 {
     if (!s) {
@@ -422,9 +425,14 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
 
     virtio_blk_data_plane_stop(s);
     bdrv_set_in_use(s->blk->conf.bs, 0);
+    object_unref(OBJECT(s->iothread));
+    if (s->internal_iothread) {
+        object_unparent(OBJECT(s->iothread));
+    }
     g_free(s);
 }
 
+/* Context: QEMU global mutex held */
 void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
 {
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev)));
@@ -448,8 +456,6 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
         return;
     }
 
-    s->ctx = aio_context_new();
-
     /* Set up guest notifier (irq) */
     if (k->set_guest_notifiers(qbus->parent, 1, true) != 0) {
         fprintf(stderr, "virtio-blk failed to set guest notifier, "
@@ -464,7 +470,6 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
         exit(1);
     }
     s->host_notifier = *virtio_queue_get_host_notifier(vq);
-    aio_set_event_notifier(s->ctx, &s->host_notifier, handle_notify);
 
     /* Set up ioqueue */
     ioq_init(&s->ioqueue, s->fd, REQ_MAX);
@@ -472,7 +477,6 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
         ioq_put_iocb(&s->ioqueue, &s->requests[i].iocb);
     }
     s->io_notifier = *ioq_get_notifier(&s->ioqueue);
-    aio_set_event_notifier(s->ctx, &s->io_notifier, handle_io);
 
     s->starting = false;
     s->started = true;
@@ -481,11 +485,14 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
     /* Kick right away to begin processing requests already in vring */
     event_notifier_set(virtio_queue_get_host_notifier(vq));
 
-    /* Spawn thread in BH so it inherits iothread cpusets */
-    s->start_bh = qemu_bh_new(start_data_plane_bh, s);
-    qemu_bh_schedule(s->start_bh);
+    /* Get this show started by hooking up our callbacks */
+    aio_context_acquire(s->ctx);
+    aio_set_event_notifier(s->ctx, &s->host_notifier, handle_notify);
+    aio_set_event_notifier(s->ctx, &s->io_notifier, handle_io);
+    aio_context_release(s->ctx);
 }
 
+/* Context: QEMU global mutex held */
 void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
 {
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s->vdev)));
@@ -496,27 +503,32 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
     s->stopping = true;
     trace_virtio_blk_data_plane_stop(s);
 
-    /* Stop thread or cancel pending thread creation BH */
-    if (s->start_bh) {
-        qemu_bh_delete(s->start_bh);
-        s->start_bh = NULL;
-    } else {
-        aio_notify(s->ctx);
-        qemu_thread_join(&s->thread);
+    aio_context_acquire(s->ctx);
+
+    /* Stop notifications for new requests from guest */
+    aio_set_event_notifier(s->ctx, &s->host_notifier, NULL);
+
+    /* Complete pending requests */
+    while (s->num_reqs > 0) {
+        aio_poll(s->ctx, true);
     }
 
+    /* Stop ioq callbacks (there are no pending requests left) */
     aio_set_event_notifier(s->ctx, &s->io_notifier, NULL);
-    ioq_cleanup(&s->ioqueue);
 
-    aio_set_event_notifier(s->ctx, &s->host_notifier, NULL);
-    k->set_host_notifier(qbus->parent, 0, false);
+    aio_context_release(s->ctx);
 
-    aio_context_unref(s->ctx);
+    /* Sync vring state back to virtqueue so that non-dataplane request
+     * processing can continue when we disable the host notifier below.
+     */
+    vring_teardown(&s->vring, s->vdev, 0);
+
+    ioq_cleanup(&s->ioqueue);
+    k->set_host_notifier(qbus->parent, 0, false);
 
     /* Clean up guest notifier (irq) */
     k->set_guest_notifiers(qbus->parent, 1, false);
 
-    vring_teardown(&s->vring, s->vdev, 0);
     s->started = false;
     s->stopping = false;
 }