hw/dataplane/ioq.h

   1 /*
   2  * Linux AIO request queue
   3  *
   4  * Copyright 2012 IBM, Corp.
   5  * Copyright 2012 Red Hat, Inc. and/or its affiliates
   6  *
   7  * Authors:
   8  *   Stefan Hajnoczi <stefanha@redhat.com>
   9  *
  10  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  11  * See the COPYING file in the top-level directory.
  12  *
  13  */
  14
  15 #ifndef IOQ_H
  16 #define IOQ_H
  17
  18 #include <libaio.h>
  19 #include "qemu/event_notifier.h"
  20
  21 typedef struct {
  22     int fd;                         /* file descriptor */
  23     unsigned int max_reqs;          /* max length of freelist and queue */
  24
  25     io_context_t io_ctx;            /* Linux AIO context */
  26     EventNotifier io_notifier;      /* Linux AIO eventfd */
  27
  28     /* Requests can complete in any order so a free list is necessary to manage
  29      * available iocbs.
  30      */
  31     struct iocb **freelist;         /* free iocbs */
  32     unsigned int freelist_idx;
  33
  34     /* Multiple requests are queued up before submitting them all in one go */
  35     struct iocb **queue;            /* queued iocbs */
  36     unsigned int queue_idx;
  37 } IOQueue;
  38
  39 void ioq_init(IOQueue *ioq, int fd, unsigned int max_reqs);
  40 void ioq_cleanup(IOQueue *ioq);
  41 EventNotifier *ioq_get_notifier(IOQueue *ioq);
  42 struct iocb *ioq_get_iocb(IOQueue *ioq);
  43 void ioq_put_iocb(IOQueue *ioq, struct iocb *iocb);
  44 struct iocb *ioq_rdwr(IOQueue *ioq, bool read, struct iovec *iov,
  45                       unsigned int count, long long offset);
  46 int ioq_submit(IOQueue *ioq);
  47
  48 static inline unsigned int ioq_num_queued(IOQueue *ioq)
  49 {
  50     return ioq->queue_idx;
  51 }
  52
  53 typedef void IOQueueCompletion(struct iocb *iocb, ssize_t ret, void *opaque);
  54 int ioq_run_completion(IOQueue *ioq, IOQueueCompletion *completion,
  55                        void *opaque);
  56
  57 #endif /* IOQ_H */