include/linux/aio.h

   1 #ifndef __LINUX__AIO_H
   2 #define __LINUX__AIO_H
   3
   4 #include <linux/list.h>
   5 #include <linux/workqueue.h>
   6 #include <linux/aio_abi.h>
   7 #include <linux/uio.h>
   8 #include <linux/rcupdate.h>
   9
  10 #include <linux/atomic.h>
  11
  12 struct kioctx;
  13 struct kiocb;
  14
  15 #define KIOCB_KEY               0
  16
  17 /*
  18  * We use ki_cancel == KIOCB_CANCELLED to indicate that a kiocb has been either
  19  * cancelled or completed (this makes a certain amount of sense because
  20  * successful cancellation - io_cancel() - does deliver the completion to
  21  * userspace).
  22  *
  23  * And since most things don't implement kiocb cancellation and we'd really like
  24  * kiocb completion to be lockless when possible, we use ki_cancel to
  25  * synchronize cancellation and completion - we only set it to KIOCB_CANCELLED
  26  * with xchg() or cmpxchg(), see batch_complete_aio() and kiocb_cancel().
  27  */
  28 #define KIOCB_CANCELLED         ((void *) (~0ULL))
  29
  30 typedef int (kiocb_cancel_fn)(struct kiocb *);
  31
  32 struct kiocb {
  33         struct file             *ki_filp;
  34         struct kioctx           *ki_ctx;        /* NULL for sync ops */
  35         kiocb_cancel_fn         *ki_cancel;
  36         void                    *private;
  37
  38         union {
  39                 void __user             *user;
  40                 struct task_struct      *tsk;
  41         } ki_obj;
  42
  43         __u64                   ki_user_data;   /* user's data for completion */
  44         loff_t                  ki_pos;
  45         size_t                  ki_nbytes;      /* copy of iocb->aio_nbytes */
  46
  47         struct list_head        ki_list;        /* the aio core uses this
  48                                                  * for cancellation */
  49
  50         /*
  51          * If the aio_resfd field of the userspace iocb is not zero,
  52          * this is the underlying eventfd context to deliver events to.
  53          */
  54         struct eventfd_ctx      *ki_eventfd;
  55 };
  56
  57 static inline bool is_sync_kiocb(struct kiocb *kiocb)
  58 {
  59         return kiocb->ki_ctx == NULL;
  60 }
  61
  62 static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
  63 {
  64         *kiocb = (struct kiocb) {
  65                         .ki_ctx = NULL,
  66                         .ki_filp = filp,
  67                         .ki_obj.tsk = current,
  68                 };
  69 }
  70
  71 /* prototypes */
  72 #ifdef CONFIG_AIO
  73 extern ssize_t wait_on_sync_kiocb(struct kiocb *iocb);
  74 extern void aio_complete(struct kiocb *iocb, long res, long res2);
  75 struct mm_struct;
  76 extern void exit_aio(struct mm_struct *mm);
  77 extern long do_io_submit(aio_context_t ctx_id, long nr,
  78                          struct iocb __user *__user *iocbpp, bool compat);
  79 void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel);
  80 #else
  81 static inline ssize_t wait_on_sync_kiocb(struct kiocb *iocb) { return 0; }
  82 static inline void aio_complete(struct kiocb *iocb, long res, long res2) { }
  83 struct mm_struct;
  84 static inline void exit_aio(struct mm_struct *mm) { }
  85 static inline long do_io_submit(aio_context_t ctx_id, long nr,
  86                                 struct iocb __user * __user *iocbpp,
  87                                 bool compat) { return 0; }
  88 static inline void kiocb_set_cancel_fn(struct kiocb *req,
  89                                        kiocb_cancel_fn *cancel) { }
  90 #endif /* CONFIG_AIO */
  91
  92 static inline struct kiocb *list_kiocb(struct list_head *h)
  93 {
  94         return list_entry(h, struct kiocb, ki_list);
  95 }
  96
  97 /* for sysctl: */
  98 extern unsigned long aio_nr;
  99 extern unsigned long aio_max_nr;
 100
 101 #endif /* __LINUX__AIO_H */