The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*-
    2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 1997 John S. Dyson.  All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. John S. Dyson's name may not be used to endorse or promote products
   12  *    derived from this software without specific prior written permission.
   13  *
   14  * DISCLAIMER:  This code isn't warranted to do anything useful.  Anything
   15  * bad that happens because of using this software isn't the responsibility
   16  * of the author.  This software is distributed AS-IS.
   17  *
   18  * $FreeBSD: stable/12/sys/sys/aio.h 329174 2018-02-12 17:42:28Z asomers $
   19  */
   20 
   21 #ifndef _SYS_AIO_H_
   22 #define _SYS_AIO_H_
   23 
   24 #include <sys/types.h>
   25 #include <sys/signal.h>
   26 #ifdef _KERNEL
   27 #include <sys/queue.h>
   28 #include <sys/event.h>
   29 #include <sys/signalvar.h>
   30 #endif
   31 
   32 /*
   33  * Returned by aio_cancel:
   34  */
   35 #define AIO_CANCELED            0x1
   36 #define AIO_NOTCANCELED         0x2
   37 #define AIO_ALLDONE             0x3
   38 
   39 /*
   40  * LIO opcodes
   41  */
   42 #define LIO_NOP                 0x0
   43 #define LIO_WRITE               0x1
   44 #define LIO_READ                0x2
   45 #ifdef _KERNEL
   46 #define LIO_SYNC                0x3
   47 #define LIO_MLOCK               0x4
   48 #endif
   49 
   50 /*
   51  * LIO modes
   52  */
   53 #define LIO_NOWAIT              0x0
   54 #define LIO_WAIT                0x1
   55 
   56 /*
   57  * Maximum number of operations in a single lio_listio call
   58  */
   59 #define AIO_LISTIO_MAX          16
   60 
   61 #ifdef _KERNEL
   62 
   63 /* Default values of tunables for the AIO worker pool. */
   64 
   65 #ifndef MAX_AIO_PROCS
   66 #define MAX_AIO_PROCS           32
   67 #endif
   68 
   69 #ifndef TARGET_AIO_PROCS
   70 #define TARGET_AIO_PROCS        4
   71 #endif
   72 
   73 #ifndef AIOD_LIFETIME_DEFAULT
   74 #define AIOD_LIFETIME_DEFAULT   (30 * hz)
   75 #endif
   76 
   77 #endif
   78 
   79 /*
   80  * Private members for aiocb -- don't access
   81  * directly.
   82  */
   83 struct __aiocb_private {
   84         long    status;
   85         long    error;
   86         void    *kernelinfo;
   87 };
   88 
   89 /*
   90  * I/O control block
   91  */
   92 typedef struct aiocb {
   93         int     aio_fildes;             /* File descriptor */
   94         off_t   aio_offset;             /* File offset for I/O */
   95         volatile void *aio_buf;         /* I/O buffer in process space */
   96         size_t  aio_nbytes;             /* Number of bytes for I/O */
   97         int     __spare__[2];
   98         void    *__spare2__;
   99         int     aio_lio_opcode;         /* LIO opcode */
  100         int     aio_reqprio;            /* Request priority -- ignored */
  101         struct  __aiocb_private _aiocb_private;
  102         struct  sigevent aio_sigevent;  /* Signal to deliver */
  103 } aiocb_t;
  104 
  105 #ifdef _KERNEL
  106 
  107 typedef void aio_cancel_fn_t(struct kaiocb *);
  108 typedef void aio_handle_fn_t(struct kaiocb *);
  109 
  110 /*
  111  * Kernel version of an I/O control block.
  112  *
  113  * Locking key:
  114  * * - need not protected
  115  * a - locked by kaioinfo lock
  116  * b - locked by backend lock
  117  * c - locked by aio_job_mtx
  118  */
  119 struct kaiocb {
  120         TAILQ_ENTRY(kaiocb) list;       /* (b) backend-specific list of jobs */
  121         TAILQ_ENTRY(kaiocb) plist;      /* (a) lists of pending / done jobs */
  122         TAILQ_ENTRY(kaiocb) allist;     /* (a) list of all jobs in proc */
  123         int     jobflags;               /* (a) job flags */
  124         int     inblock;                /* (*) input blocks */
  125         int     outblock;               /* (*) output blocks */
  126         int     msgsnd;                 /* (*) messages sent */
  127         int     msgrcv;                 /* (*) messages received */
  128         struct  proc *userproc;         /* (*) user process */
  129         struct  ucred *cred;            /* (*) active credential when created */
  130         struct  file *fd_file;          /* (*) pointer to file structure */
  131         struct  aioliojob *lio;         /* (*) optional lio job */
  132         struct  aiocb *ujob;            /* (*) pointer in userspace of aiocb */
  133         struct  knlist klist;           /* (a) list of knotes */
  134         struct  aiocb uaiocb;           /* (*) copy of user I/O control block */
  135         ksiginfo_t ksi;                 /* (a) realtime signal info */
  136         uint64_t seqno;                 /* (*) job number */
  137         aio_cancel_fn_t *cancel_fn;     /* (a) backend cancel function */
  138         aio_handle_fn_t *handle_fn;     /* (c) backend handle function */
  139         union {                         /* Backend-specific data fields */
  140                 struct {                /* BIO backend */
  141                         struct bio *bp; /* (*) BIO pointer */
  142                         struct buf *pbuf; /* (*) buffer pointer */
  143                         struct vm_page *pages[btoc(MAXPHYS)+1]; /* (*) */
  144                         int     npages; /* (*) number of pages */
  145                 };
  146                 struct {                /* fsync() requests */
  147                         int     pending; /* (a) number of pending I/O */
  148                 };
  149                 struct {
  150                         void    *backend1;
  151                         void    *backend2;
  152                         long    backend3;
  153                         int     backend4;
  154                 };
  155         };
  156 };
  157 
  158 struct socket;
  159 struct sockbuf;
  160 
  161 /*
  162  * AIO backends should permit cancellation of queued requests waiting to
  163  * be serviced by installing a cancel routine while the request is
  164  * queued.  The cancellation routine should dequeue the request if
  165  * necessary and cancel it.  Care must be used to handle races between
  166  * queueing and dequeueing requests and cancellation.
  167  *
  168  * When queueing a request somewhere such that it can be cancelled, the
  169  * caller should:
  170  *
  171  *  1) Acquire lock that protects the associated queue.
  172  *  2) Call aio_set_cancel_function() to install the cancel routine.
  173  *  3) If that fails, the request has a pending cancel and should be
  174  *     cancelled via aio_cancel().
  175  *  4) Queue the request.
  176  *
  177  * When dequeueing a request to service it or hand it off to somewhere else,
  178  * the caller should:
  179  *
  180  *  1) Acquire the lock that protects the associated queue.
  181  *  2) Dequeue the request.
  182  *  3) Call aio_clear_cancel_function() to clear the cancel routine.
  183  *  4) If that fails, the cancel routine is about to be called.  The
  184  *     caller should ignore the request.
  185  *
  186  * The cancel routine should:
  187  *
  188  *  1) Acquire the lock that protects the associated queue.
  189  *  2) Call aio_cancel_cleared() to determine if the request is already
  190  *     dequeued due to a race with dequeueing thread.
  191  *  3) If that fails, dequeue the request.
  192  *  4) Cancel the request via aio_cancel().
  193  */
  194 
  195 bool    aio_cancel_cleared(struct kaiocb *job);
  196 void    aio_cancel(struct kaiocb *job);
  197 bool    aio_clear_cancel_function(struct kaiocb *job);
  198 void    aio_complete(struct kaiocb *job, long status, int error);
  199 void    aio_schedule(struct kaiocb *job, aio_handle_fn_t *func);
  200 bool    aio_set_cancel_function(struct kaiocb *job, aio_cancel_fn_t *func);
  201 void    aio_switch_vmspace(struct kaiocb *job);
  202 
  203 #else /* !_KERNEL */
  204 
  205 struct timespec;
  206 
  207 __BEGIN_DECLS
  208 /*
  209  * Asynchronously read from a file
  210  */
  211 int     aio_read(struct aiocb *);
  212 
  213 /*
  214  * Asynchronously write to file
  215  */
  216 int     aio_write(struct aiocb *);
  217 
  218 /*
  219  * List I/O Asynchronously/synchronously read/write to/from file
  220  *      "lio_mode" specifies whether or not the I/O is synchronous.
  221  *      "acb_list" is an array of "nacb_listent" I/O control blocks.
  222  *      when all I/Os are complete, the optional signal "sig" is sent.
  223  */
  224 int     lio_listio(int, struct aiocb *__restrict const *__restrict, int,
  225     struct sigevent *);
  226 
  227 /*
  228  * Get completion status
  229  *      returns EINPROGRESS until I/O is complete.
  230  *      this routine does not block.
  231  */
  232 int     aio_error(const struct aiocb *);
  233 
  234 /*
  235  * Finish up I/O, releasing I/O resources and returns the value
  236  *      that would have been associated with a synchronous I/O request.
  237  *      This routine must be called once and only once for each
  238  *      I/O control block who has had I/O associated with it.
  239  */
  240 ssize_t aio_return(struct aiocb *);
  241 
  242 /*
  243  * Cancel I/O
  244  */
  245 int     aio_cancel(int, struct aiocb *);
  246 
  247 /*
  248  * Suspend until all specified I/O or timeout is complete.
  249  */
  250 int     aio_suspend(const struct aiocb * const[], int, const struct timespec *);
  251 
  252 /*
  253  * Asynchronous mlock
  254  */
  255 int     aio_mlock(struct aiocb *);
  256 
  257 #if __BSD_VISIBLE
  258 ssize_t aio_waitcomplete(struct aiocb **, struct timespec *);
  259 #endif
  260 
  261 int     aio_fsync(int op, struct aiocb *aiocbp);
  262 __END_DECLS
  263 
  264 #endif /* !_KERNEL */
  265 
  266 #endif /* !_SYS_AIO_H_ */

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