FreeBSD/Linux Kernel Cross Reference
sys/sys/aio.h

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 1997 John S. Dyson.  All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. John S. Dyson's name may not be used to endorse or promote products
     *    derived from this software without specific prior written permission.
     *
     * DISCLAIMER:  This code isn't warranted to do anything useful.  Anything
     * bad that happens because of using this software isn't the responsibility
     * of the author.  This software is distributed AS-IS.
     *
     * $FreeBSD$
     */
    
    #ifndef _SYS_AIO_H_
    #define _SYS_AIO_H_
    
    #include <sys/types.h>
    #include <sys/signal.h>
    #ifdef _KERNEL
    #include <sys/queue.h>
    #include <sys/event.h>
    #include <sys/signalvar.h>
    #endif
    
    /*
     * Returned by aio_cancel:
     */
    #define AIO_CANCELED            0x1
    #define AIO_NOTCANCELED         0x2
    #define AIO_ALLDONE             0x3
    
    /*
     * LIO opcodes
     */
    #define LIO_NOP                 0x0
    #define LIO_WRITE               0x1
    #define LIO_READ                0x2
    #ifdef _KERNEL
    #define LIO_SYNC                0x3
    #define LIO_MLOCK               0x4
    #endif
    
    /*
     * LIO modes
     */
    #define LIO_NOWAIT              0x0
    #define LIO_WAIT                0x1
    
    /*
     * Maximum number of operations in a single lio_listio call
     */
    #define AIO_LISTIO_MAX          16
    
    #ifdef _KERNEL
    
    /* Default values of tunables for the AIO worker pool. */
    
    #ifndef MAX_AIO_PROCS
    #define MAX_AIO_PROCS           32
    #endif
    
    #ifndef TARGET_AIO_PROCS
    #define TARGET_AIO_PROCS        4
    #endif
    
    #ifndef AIOD_LIFETIME_DEFAULT
    #define AIOD_LIFETIME_DEFAULT   (30 * hz)
    #endif
    
    #endif
    
    /*
     * Private members for aiocb -- don't access
     * directly.
     */
    struct __aiocb_private {
            long    status;
            long    error;
            void    *kernelinfo;
    };
    
    /*
     * I/O control block
     */
    typedef struct aiocb {
            int     aio_fildes;             /* File descriptor */
            off_t   aio_offset;             /* File offset for I/O */
            volatile void *aio_buf;         /* I/O buffer in process space */
            size_t  aio_nbytes;             /* Number of bytes for I/O */
            int     __spare__[2];
            void    *__spare2__;
            int     aio_lio_opcode;         /* LIO opcode */
           int     aio_reqprio;            /* Request priority -- ignored */
           struct  __aiocb_private _aiocb_private;
           struct  sigevent aio_sigevent;  /* Signal to deliver */
   } aiocb_t;
   
   #ifdef _KERNEL
   
   typedef void aio_cancel_fn_t(struct kaiocb *);
   typedef void aio_handle_fn_t(struct kaiocb *);
   
   /*
    * Kernel version of an I/O control block.
    *
    * Locking key:
    * * - need not protected
    * a - locked by kaioinfo lock
    * b - locked by backend lock
    * c - locked by aio_job_mtx
    */
   struct kaiocb {
           TAILQ_ENTRY(kaiocb) list;       /* (b) backend-specific list of jobs */
           TAILQ_ENTRY(kaiocb) plist;      /* (a) lists of pending / done jobs */
           TAILQ_ENTRY(kaiocb) allist;     /* (a) list of all jobs in proc */
           int     jobflags;               /* (a) job flags */
           int     inblock;                /* (*) input blocks */
           int     outblock;               /* (*) output blocks */
           int     msgsnd;                 /* (*) messages sent */
           int     msgrcv;                 /* (*) messages received */
           struct  proc *userproc;         /* (*) user process */
           struct  ucred *cred;            /* (*) active credential when created */
           struct  file *fd_file;          /* (*) pointer to file structure */
           struct  aioliojob *lio;         /* (*) optional lio job */
           struct  aiocb *ujob;            /* (*) pointer in userspace of aiocb */
           struct  knlist klist;           /* (a) list of knotes */
           struct  aiocb uaiocb;           /* (*) copy of user I/O control block */
           ksiginfo_t ksi;                 /* (a) realtime signal info */
           uint64_t seqno;                 /* (*) job number */
           aio_cancel_fn_t *cancel_fn;     /* (a) backend cancel function */
           aio_handle_fn_t *handle_fn;     /* (c) backend handle function */
           union {                         /* Backend-specific data fields */
                   struct {                /* BIO backend */
                           struct bio *bp; /* (*) BIO pointer */
                           struct buf *pbuf; /* (*) buffer pointer */
                           struct vm_page *pages[btoc(MAXPHYS)+1]; /* (*) */
                           int     npages; /* (*) number of pages */
                   };
                   struct {                /* fsync() requests */
                           int     pending; /* (a) number of pending I/O */
                   };
                   struct {
                           void    *backend1;
                           void    *backend2;
                           long    backend3;
                           int     backend4;
                   };
           };
   };
   
   struct socket;
   struct sockbuf;
   
   /*
    * AIO backends should permit cancellation of queued requests waiting to
    * be serviced by installing a cancel routine while the request is
    * queued.  The cancellation routine should dequeue the request if
    * necessary and cancel it.  Care must be used to handle races between
    * queueing and dequeueing requests and cancellation.
    *
    * When queueing a request somewhere such that it can be cancelled, the
    * caller should:
    *
    *  1) Acquire lock that protects the associated queue.
    *  2) Call aio_set_cancel_function() to install the cancel routine.
    *  3) If that fails, the request has a pending cancel and should be
    *     cancelled via aio_cancel().
    *  4) Queue the request.
    *
    * When dequeueing a request to service it or hand it off to somewhere else,
    * the caller should:
    *
    *  1) Acquire the lock that protects the associated queue.
    *  2) Dequeue the request.
    *  3) Call aio_clear_cancel_function() to clear the cancel routine.
    *  4) If that fails, the cancel routine is about to be called.  The
    *     caller should ignore the request.
    *
    * The cancel routine should:
    *
    *  1) Acquire the lock that protects the associated queue.
    *  2) Call aio_cancel_cleared() to determine if the request is already
    *     dequeued due to a race with dequeueing thread.
    *  3) If that fails, dequeue the request.
    *  4) Cancel the request via aio_cancel().
    */
   
   bool    aio_cancel_cleared(struct kaiocb *job);
   void    aio_cancel(struct kaiocb *job);
   bool    aio_clear_cancel_function(struct kaiocb *job);
   void    aio_complete(struct kaiocb *job, long status, int error);
   void    aio_schedule(struct kaiocb *job, aio_handle_fn_t *func);
   bool    aio_set_cancel_function(struct kaiocb *job, aio_cancel_fn_t *func);
   void    aio_switch_vmspace(struct kaiocb *job);
   
   #else /* !_KERNEL */
   
   struct timespec;
   
   __BEGIN_DECLS
   /*
    * Asynchronously read from a file
    */
   int     aio_read(struct aiocb *);
   
   /*
    * Asynchronously write to file
    */
   int     aio_write(struct aiocb *);
   
   /*
    * List I/O Asynchronously/synchronously read/write to/from file
    *      "lio_mode" specifies whether or not the I/O is synchronous.
    *      "acb_list" is an array of "nacb_listent" I/O control blocks.
    *      when all I/Os are complete, the optional signal "sig" is sent.
    */
   int     lio_listio(int, struct aiocb *__restrict const *__restrict, int,
       struct sigevent *);
   
   /*
    * Get completion status
    *      returns EINPROGRESS until I/O is complete.
    *      this routine does not block.
    */
   int     aio_error(const struct aiocb *);
   
   /*
    * Finish up I/O, releasing I/O resources and returns the value
    *      that would have been associated with a synchronous I/O request.
    *      This routine must be called once and only once for each
    *      I/O control block who has had I/O associated with it.
    */
   ssize_t aio_return(struct aiocb *);
   
   /*
    * Cancel I/O
    */
   int     aio_cancel(int, struct aiocb *);
   
   /*
    * Suspend until all specified I/O or timeout is complete.
    */
   int     aio_suspend(const struct aiocb * const[], int, const struct timespec *);
   
   /*
    * Asynchronous mlock
    */
   int     aio_mlock(struct aiocb *);
   
   #if __BSD_VISIBLE
   ssize_t aio_waitcomplete(struct aiocb **, struct timespec *);
   #endif
   
   int     aio_fsync(int op, struct aiocb *aiocbp);
   __END_DECLS
   
   #endif /* !_KERNEL */
   
   #endif /* !_SYS_AIO_H_ */

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