On Tue, Aug 9, 2011 at 4:46 PM, Ram Pai <linuxram@xxxxxxxxxx> wrote:
> On Tue, Aug 09, 2011 at 12:17:50PM +0800, Zhi Yong Wu wrote:
>> The patch introduce one block queue for QEMU block layer.
>>
>> Signed-off-by: Zhi Yong Wu <wuzhy@xxxxxxxxxxxxxxxxxx>
>> ---
>> block/blk-queue.c | 141 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>> block/blk-queue.h | 73 +++++++++++++++++++++++++++
>> 2 files changed, 214 insertions(+), 0 deletions(-)
>> create mode 100644 block/blk-queue.c
>> create mode 100644 block/blk-queue.h
>>
>> diff --git a/block/blk-queue.c b/block/blk-queue.c
>> new file mode 100644
>> index 0000000..f36f3e2
>> --- /dev/null
>> +++ b/block/blk-queue.c
>> @@ -0,0 +1,141 @@
>> +/*
>> + * QEMU System Emulator queue definition for block layer
>> + *
>> + * Copyright (c) 2011 Zhi Yong Wu <zwu.kernel@xxxxxxxxx>
>> + *
>> + * 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);
>
>
> should'nt you return with a failure here if res == NULL?
> Otherwise qemu_block_queue_callback() gets called which
> will release the acb.
Thanks, Pai. When req handler fails, acb should not be released. A
condition determination should be done before callback function is
invoked. It should be like as below:
res = request->handler(request->bs, request->sector_num,
request->qiov, request->nb_sectors,
request->cb, request->opaque);
ret = (res == NULL) ? 0 : 1;
if ( ret && request->acb) {
qemu_block_queue_callback(request->acb, 0);
}
>
>
>> +
>> + if (request->acb) {
>> + qemu_block_queue_callback(request->acb, 0);
>> + }
>> +
>> + ret = (res == NULL) ? 0 : 1;
>> +
>> + return ret;
>> +}
>
>
> RP
>
>
--
Regards,
Zhi Yong Wu
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