qemu-aio.h

   1 /*
   2  * QEMU aio implementation
   3  *
   4  * Copyright IBM, Corp. 2008
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #ifndef QEMU_AIO_H
  15 #define QEMU_AIO_H
  16
  17 #include "qemu-common.h"
  18 #include "qemu-char.h"
  19
  20 typedef struct BlockDriverAIOCB BlockDriverAIOCB;
  21 typedef void BlockDriverCompletionFunc(void *opaque, int ret);
  22
  23 typedef struct AIOPool {
  24     void (*cancel)(BlockDriverAIOCB *acb);
  25     int aiocb_size;
  26     BlockDriverAIOCB *free_aiocb;
  27 } AIOPool;
  28
  29 struct BlockDriverAIOCB {
  30     AIOPool *pool;
  31     BlockDriverState *bs;
  32     BlockDriverCompletionFunc *cb;
  33     void *opaque;
  34     BlockDriverAIOCB *next;
  35 };
  36
  37 void *qemu_aio_get(AIOPool *pool, BlockDriverState *bs,
  38                    BlockDriverCompletionFunc *cb, void *opaque);
  39 void qemu_aio_release(void *p);
  40
  41 /* Returns 1 if there are still outstanding AIO requests; 0 otherwise */
  42 typedef int (AioFlushHandler)(void *opaque);
  43
  44 /* Flush any pending AIO operation. This function will block until all
  45  * outstanding AIO operations have been completed or cancelled. */
  46 void qemu_aio_flush(void);
  47
  48 /* Wait for a single AIO completion to occur.  This function will wait
  49  * until a single AIO event has completed and it will ensure something
  50  * has moved before returning. This can issue new pending aio as
  51  * result of executing I/O completion or bh callbacks.
  52  *
  53  * Return whether there is still any pending AIO operation.  */
  54 bool qemu_aio_wait(void);
  55
  56 /* Register a file descriptor and associated callbacks.  Behaves very similarly
  57  * to qemu_set_fd_handler2.  Unlike qemu_set_fd_handler2, these callbacks will
  58  * be invoked when using either qemu_aio_wait() or qemu_aio_flush().
  59  *
  60  * Code that invokes AIO completion functions should rely on this function
  61  * instead of qemu_set_fd_handler[2].
  62  */
  63 int qemu_aio_set_fd_handler(int fd,
  64                             IOHandler *io_read,
  65                             IOHandler *io_write,
  66                             AioFlushHandler *io_flush,
  67                             void *opaque);
  68
  69 #endif