Patchwork [v4,2/3] The support for block queue

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Submitter Zhi Yong Wu
Date Aug. 1, 2011, 6:25 a.m.
Message ID <1312179955-23536-3-git-send-email-wuzhy@linux.vnet.ibm.com>
Download mbox | patch
Permalink /patch/107672/
State New
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Comments

Zhi Yong Wu - Aug. 1, 2011, 6:25 a.m.
Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
---
 block/blk-queue.c |  122 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 block/blk-queue.h |   71 +++++++++++++++++++++++++++++++
 2 files changed, 193 insertions(+), 0 deletions(-)
 create mode 100644 block/blk-queue.c
 create mode 100644 block/blk-queue.h
Ryan Harper - Aug. 1, 2011, 8:21 p.m.
* Zhi Yong Wu <wuzhy@linux.vnet.ibm.com> [2011-08-01 01:30]:

> +static AIOPool block_queue_pool = {
> +    .aiocb_size         = sizeof(struct BlockDriverAIOCB),
> +    .cancel             = qemu_block_queue_cancel,
> +};
> +
> +static void qemu_block_queue_callback(void *opaque, int ret)
> +{
> +    BlockDriverAIOCB *acb = opaque;
> +
> +    qemu_aio_release(acb);
> +}
> +

So, here we really want to invoke the original commands callback, and
then free the request here (via qemu_aio_release()).  see below.


> +BlockDriverAIOCB *qemu_block_queue_enqueue(BlockQueue *queue,
> +                        BlockDriverState *bs,
> +                        BlockRequestHandler *handler,
> +                        int64_t sector_num,
> +                        QEMUIOVector *qiov,
> +                        int nb_sectors,
> +                        BlockDriverCompletionFunc *cb,
> +                        void *opaque)
> +{
> +    BlockIORequest *request;
> +    BlockDriverAIOCB *acb;
> +
> +    request = qemu_malloc(sizeof(BlockIORequest));
> +    request->bs = bs;
> +    request->handler = handler;
> +    request->sector_num = sector_num;
> +    request->qiov = qiov;
> +    request->nb_sectors = nb_sectors;
> +    request->cb = cb;
> +    request->opaque = opaque;
> +
> +    QTAILQ_INSERT_TAIL(&queue->requests, request, entry);
> +
> +    acb = qemu_aio_get(&block_queue_pool, bs,
> +                       qemu_block_queue_callback, opaque);
> +    request->acb = acb;
> +
> +    return acb;
> +}
> +
> +int qemu_block_queue_handler(BlockIORequest *request)
> +{
> +    int ret;
> +    BlockDriverAIOCB *res;
> +
> +    /* indicate this req is from block queue */
> +    request->bs->req_from_queue = true;
> +
> +    res = request->handler(request->bs, request->sector_num,
> +                           request->qiov, request->nb_sectors,
> +                           request->cb, request->opaque);
> +
> +    if (request->acb) {
> +        qemu_block_queue_callback(request->acb, 0);
> +    }
> +
> +    ret = (res == NULL) ? 0 : 1;
> +
> +    return ret;
> +}


You don't want to malloc the BlockIORequest directly in _enqueue(), rather
you want to allocate that from your AIOPool via qemu_aio_get().  As it
is now, we're allocating two BlockIORequests (malloc and then a
aio_get()).  You'll need a BlockDriverAIOCB in the BlockIORequest
structure.  Then in your queue_handler, instead of passing the original
read or write callback (request->cb), you want to hook the block_queue callback
(qemu_block_queue_callback()), in that callback you can then invoke the
request callback and then release the request.

The request should be, only one malloc (via the pool which will re-use
the memory instead of incuring a malloc on every request), and then you 
release the memory back to the pool once your request is complete, which
you'll know after wiring up the block_queue callback to the completion
of the request's handler.  And then since we don't double allocate, you
won't need to do the qemu_free(request) in block.c in block_timer...
Zhiyong Wu - Aug. 5, 2011, 2:57 a.m.
On Tue, Aug 2, 2011 at 4:21 AM, Ryan Harper <ryanh@us.ibm.com> wrote:
> * Zhi Yong Wu <wuzhy@linux.vnet.ibm.com> [2011-08-01 01:30]:
>
>> +static AIOPool block_queue_pool = {
>> +    .aiocb_size         = sizeof(struct BlockDriverAIOCB),
>> +    .cancel             = qemu_block_queue_cancel,
>> +};
>> +
>> +static void qemu_block_queue_callback(void *opaque, int ret)
>> +{
>> +    BlockDriverAIOCB *acb = opaque;
>> +
>> +    qemu_aio_release(acb);
>> +}
>> +
>
> So, here we really want to invoke the original commands callback, and
> then free the request here (via qemu_aio_release()).  see below.
>
>
>> +BlockDriverAIOCB *qemu_block_queue_enqueue(BlockQueue *queue,
>> +                        BlockDriverState *bs,
>> +                        BlockRequestHandler *handler,
>> +                        int64_t sector_num,
>> +                        QEMUIOVector *qiov,
>> +                        int nb_sectors,
>> +                        BlockDriverCompletionFunc *cb,
>> +                        void *opaque)
>> +{
>> +    BlockIORequest *request;
>> +    BlockDriverAIOCB *acb;
>> +
>> +    request = qemu_malloc(sizeof(BlockIORequest));
>> +    request->bs = bs;
>> +    request->handler = handler;
>> +    request->sector_num = sector_num;
>> +    request->qiov = qiov;
>> +    request->nb_sectors = nb_sectors;
>> +    request->cb = cb;
>> +    request->opaque = opaque;
>> +
>> +    QTAILQ_INSERT_TAIL(&queue->requests, request, entry);
>> +
>> +    acb = qemu_aio_get(&block_queue_pool, bs,
>> +                       qemu_block_queue_callback, opaque);
>> +    request->acb = acb;
>> +
>> +    return acb;
>> +}
>> +
>> +int qemu_block_queue_handler(BlockIORequest *request)
>> +{
>> +    int ret;
>> +    BlockDriverAIOCB *res;
>> +
>> +    /* indicate this req is from block queue */
>> +    request->bs->req_from_queue = true;
>> +
>> +    res = request->handler(request->bs, request->sector_num,
>> +                           request->qiov, request->nb_sectors,
>> +                           request->cb, request->opaque);
>> +
>> +    if (request->acb) {
>> +        qemu_block_queue_callback(request->acb, 0);
>> +    }
>> +
>> +    ret = (res == NULL) ? 0 : 1;
>> +
>> +    return ret;
>> +}
>
>
> You don't want to malloc the BlockIORequest directly in _enqueue(), rather
> you want to allocate that from your AIOPool via qemu_aio_get().  As it
> is now, we're allocating two BlockIORequests (malloc and then a
> aio_get()).  You'll need a BlockDriverAIOCB in the BlockIORequest
> structure.  Then in your queue_handler, instead of passing the original
> read or write callback (request->cb), you want to hook the block_queue callback
> (qemu_block_queue_callback()), in that callback you can then invoke the
> request callback and then release the request.
Right
>
> The request should be, only one malloc (via the pool which will re-use
> the memory instead of incuring a malloc on every request), and then you
> release the memory back to the pool once your request is complete, which
> you'll know after wiring up the block_queue callback to the completion
> of the request's handler.  And then since we don't double allocate, you
> won't need to do the qemu_free(request) in block.c in block_timer...
No, please see the comments in another patch. We need to return a
valid acb to upper layer in order to tell it the request has been
succeeded in starting. But actually the request is enqueued, so normal
acb can not be returned immediately because this request is not
handled by the driver; so we need to malloc an immediate acb struct,
and return it to upper layer.
>
>
> --
> Ryan Harper
> Software Engineer; Linux Technology Center
> IBM Corp., Austin, Tx
> ryanh@us.ibm.com
>

Patch

diff --git a/block/blk-queue.c b/block/blk-queue.c
new file mode 100644
index 0000000..332ff13
--- /dev/null
+++ b/block/blk-queue.c
@@ -0,0 +1,122 @@ 
+/*
+ * QEMU System Emulator queue definition for block layer
+ *
+ * Copyright (c) 2011 Zhi Yong Wu  <zwu.kernel@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "block_int.h"
+#include "qemu-queue.h"
+#include "block/blk-queue.h"
+
+/* The APIs for block request queue on qemu block layer.
+ */
+
+static void qemu_block_queue_cancel(BlockDriverAIOCB *acb)
+{
+    qemu_aio_release(acb);
+}
+
+static AIOPool block_queue_pool = {
+    .aiocb_size         = sizeof(struct BlockDriverAIOCB),
+    .cancel             = qemu_block_queue_cancel,
+};
+
+static void qemu_block_queue_callback(void *opaque, int ret)
+{
+    BlockDriverAIOCB *acb = opaque;
+
+    qemu_aio_release(acb);
+}
+
+BlockQueue *qemu_new_block_queue(void)
+{
+    BlockQueue *queue;
+
+    queue = qemu_mallocz(sizeof(BlockQueue));
+
+    QTAILQ_INIT(&queue->requests);
+
+    return queue;
+}
+
+void qemu_del_block_queue(BlockQueue *queue)
+{
+    BlockIORequest *request, *next;
+
+    QTAILQ_FOREACH_SAFE(request, &queue->requests, entry, next) {
+        QTAILQ_REMOVE(&queue->requests, request, entry);
+        qemu_free(request);
+    }
+
+    qemu_free(queue);
+}
+
+BlockDriverAIOCB *qemu_block_queue_enqueue(BlockQueue *queue,
+                        BlockDriverState *bs,
+                        BlockRequestHandler *handler,
+                        int64_t sector_num,
+                        QEMUIOVector *qiov,
+                        int nb_sectors,
+                        BlockDriverCompletionFunc *cb,
+                        void *opaque)
+{
+    BlockIORequest *request;
+    BlockDriverAIOCB *acb;
+
+    request = qemu_malloc(sizeof(BlockIORequest));
+    request->bs = bs;
+    request->handler = handler;
+    request->sector_num = sector_num;
+    request->qiov = qiov;
+    request->nb_sectors = nb_sectors;
+    request->cb = cb;
+    request->opaque = opaque;
+
+    QTAILQ_INSERT_TAIL(&queue->requests, request, entry);
+
+    acb = qemu_aio_get(&block_queue_pool, bs,
+                       qemu_block_queue_callback, opaque);
+
+    request->acb = acb;
+
+    return acb;
+}
+
+int qemu_block_queue_handler(BlockIORequest *request)
+{
+    int ret;
+    BlockDriverAIOCB *res;
+
+    /* indicate this req is from block queue */
+    request->bs->req_from_queue = true;
+
+    res = request->handler(request->bs, request->sector_num,
+                           request->qiov, request->nb_sectors,
+                           request->cb, request->opaque);
+
+    if (request->acb) {
+        qemu_block_queue_callback(request->acb, 0);
+    }
+
+    ret = (res == NULL) ? 0 : 1;
+
+    return ret;
+}
diff --git a/block/blk-queue.h b/block/blk-queue.h
new file mode 100644
index 0000000..72a5b24
--- /dev/null
+++ b/block/blk-queue.h
@@ -0,0 +1,71 @@ 
+/*
+ * QEMU System Emulator queue declaration for block layer
+ *
+ * Copyright (c) 2011 Zhi Yong Wu  <zwu.kernel@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef QEMU_BLOCK_QUEUE_H
+#define QEMU_BLOCK_QUEUE_H
+
+#include "block.h"
+#include "qemu-queue.h"
+#include "qemu-common.h"
+
+typedef BlockDriverAIOCB* (BlockRequestHandler) (BlockDriverState *bs,
+                                int64_t sector_num, QEMUIOVector *qiov,
+                                int nb_sectors, BlockDriverCompletionFunc *cb,
+                                void *opaque);
+
+struct BlockIORequest {
+    QTAILQ_ENTRY(BlockIORequest) entry;
+    BlockDriverState *bs;
+    BlockRequestHandler *handler;
+    int64_t sector_num;
+    QEMUIOVector *qiov;
+    int nb_sectors;
+    BlockDriverCompletionFunc *cb;
+    void *opaque;
+    BlockDriverAIOCB *acb;
+};
+
+typedef struct BlockIORequest BlockIORequest;
+
+struct BlockQueue {
+    QTAILQ_HEAD(requests, BlockIORequest) requests;
+};
+
+typedef struct BlockQueue BlockQueue;
+
+BlockQueue *qemu_new_block_queue(void);
+
+void qemu_del_block_queue(BlockQueue *queue);
+
+BlockDriverAIOCB *qemu_block_queue_enqueue(BlockQueue *queue,
+                        BlockDriverState *bs,
+                        BlockRequestHandler *handler,
+                        int64_t sector_num,
+                        QEMUIOVector *qiov,
+                        int nb_sectors,
+                        BlockDriverCompletionFunc *cb,
+                        void *opaque);
+
+int qemu_block_queue_handler(BlockIORequest *request);
+#endif /* QEMU_BLOCK_QUEUE_H */