root/include/linux/aio.h

INCLUDED FROM

DEFINITIONS

1. is_sync_kiocb
2. init_sync_kiocb
3. wait_on_sync_kiocb
4. aio_complete
5. exit_aio
6. do_io_submit
7. kiocb_set_cancel_fn
8. list_kiocb

#ifndef __LINUX__AIO_H
#define __LINUX__AIO_H

#include <linux/list.h>
#include <linux/workqueue.h>
#include <linux/aio_abi.h>
#include <linux/uio.h>
#include <linux/rcupdate.h>

#include <linux/atomic.h>

struct kioctx;
struct kiocb;

#define KIOCB_KEY               0

/*
 * We use ki_cancel == KIOCB_CANCELLED to indicate that a kiocb has been either
 * cancelled or completed (this makes a certain amount of sense because
 * successful cancellation - io_cancel() - does deliver the completion to
 * userspace).
 *
 * And since most things don't implement kiocb cancellation and we'd really like
 * kiocb completion to be lockless when possible, we use ki_cancel to
 * synchronize cancellation and completion - we only set it to KIOCB_CANCELLED
 * with xchg() or cmpxchg(), see batch_complete_aio() and kiocb_cancel().
 */
#define KIOCB_CANCELLED         ((void *) (~0ULL))

typedef int (kiocb_cancel_fn)(struct kiocb *);

struct kiocb {
        struct file             *ki_filp;
        struct kioctx           *ki_ctx;        /* NULL for sync ops */
        kiocb_cancel_fn         *ki_cancel;
        void                    *private;

        union {
                void __user             *user;
                struct task_struct      *tsk;
        } ki_obj;

        __u64                   ki_user_data;   /* user's data for completion */
        loff_t                  ki_pos;
        size_t                  ki_nbytes;      /* copy of iocb->aio_nbytes */

        struct list_head        ki_list;        /* the aio core uses this
                                                 * for cancellation */

        /*
         * If the aio_resfd field of the userspace iocb is not zero,
         * this is the underlying eventfd context to deliver events to.
         */
        struct eventfd_ctx      *ki_eventfd;
};

static inline bool is_sync_kiocb(struct kiocb *kiocb)
{
        return kiocb->ki_ctx == NULL;
}

static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
{
        *kiocb = (struct kiocb) {
                        .ki_ctx = NULL,
                        .ki_filp = filp,
                        .ki_obj.tsk = current,
                };
}

/* prototypes */
#ifdef CONFIG_AIO
extern ssize_t wait_on_sync_kiocb(struct kiocb *iocb);
extern void aio_complete(struct kiocb *iocb, long res, long res2);
struct mm_struct;
extern void exit_aio(struct mm_struct *mm);
extern long do_io_submit(aio_context_t ctx_id, long nr,
                         struct iocb __user *__user *iocbpp, bool compat);
void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel);
#else
static inline ssize_t wait_on_sync_kiocb(struct kiocb *iocb) { return 0; }
static inline void aio_complete(struct kiocb *iocb, long res, long res2) { }
struct mm_struct;
static inline void exit_aio(struct mm_struct *mm) { }
static inline long do_io_submit(aio_context_t ctx_id, long nr,
                                struct iocb __user * __user *iocbpp,
                                bool compat) { return 0; }
static inline void kiocb_set_cancel_fn(struct kiocb *req,
                                       kiocb_cancel_fn *cancel) { }
#endif /* CONFIG_AIO */

static inline struct kiocb *list_kiocb(struct list_head *h)
{
        return list_entry(h, struct kiocb, ki_list);
}

/* for sysctl: */
extern unsigned long aio_nr;
extern unsigned long aio_max_nr;

#endif /* __LINUX__AIO_H */