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kernel/linux-imx6_3.14.28/include/linux/aio.h 2.8 KB
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  #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 */