[Qemu-devel] [RFC PATCH v2 4/8] linux-aio: Implement .cancel_async

[Fam Zheng <famz@redhat.com>]

Just call io_cancel (2), if it fails, it means the request is not
canceled, so the event loop will eventually call
qemu_laio_process_completion.

In qemu_laio_process_completion, change to call the cb unconditionally.
It is required by .cancel_async, and also acceptable by .cancel.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/linux-aio.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/block/linux-aio.c b/block/linux-aio.c
index 7ac7e8c..adf3b2e 100644
--- a/block/linux-aio.c
+++ b/block/linux-aio.c
@@ -79,9 +79,8 @@ static void qemu_laio_process_completion(struct qemu_laio_state *s,
                 ret = -EINVAL;
             }
         }
-
-        laiocb->common.cb(laiocb->common.opaque, ret);
     }
+    laiocb->common.cb(laiocb->common.opaque, ret);
 
     qemu_aio_release(laiocb);
 }
@@ -110,6 +109,22 @@ static void qemu_laio_completion_cb(EventNotifier *e)
     }
 }
 
+static void laio_cancel_async(BlockDriverAIOCB *blockacb)
+{
+    struct qemu_laiocb *laiocb = (struct qemu_laiocb *)blockacb;
+    struct io_event event;
+    int ret;
+
+    ret = io_cancel(laiocb->ctx->ctx, &laiocb->iocb, &event);
+    laiocb->ret = -ECANCELED;
+    if (!ret) {
+        /* iocb is not cancelled, cb will be called by the event loop later */
+        return;
+    }
+
+    laiocb->common.cb(laiocb->common.opaque, laiocb->ret);
+}
+
 static void laio_cancel(BlockDriverAIOCB *blockacb)
 {
     struct qemu_laiocb *laiocb = (struct qemu_laiocb *)blockacb;
@@ -145,6 +160,7 @@ static void laio_cancel(BlockDriverAIOCB *blockacb)
 static const AIOCBInfo laio_aiocb_info = {
     .aiocb_size         = sizeof(struct qemu_laiocb),
     .cancel             = laio_cancel,
+    .cancel_async       = laio_cancel_async,
 };
 
 static void ioq_init(LaioQueue *io_q)
-- 
2.1.0