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  * Copyright (c) 1997 John S. Dyson.  All rights reserved.
    3  *
    4  * Redistribution and use in source and binary forms, with or without
    5  * modification, are permitted provided that the following conditions
    6  * are met:
    7  * 1. Redistributions of source code must retain the above copyright
    8  *    notice, this list of conditions and the following disclaimer.
    9  * 2. John S. Dyson's name may not be used to endorse or promote products
   10  *    derived from this software without specific prior written permission.
   11  *
   12  * DISCLAIMER:  This code isn't warranted to do anything useful.  Anything
   13  * bad that happens because of using this software isn't the responsibility
   14  * of the author.  This software is distributed AS-IS.
   15  *
   16  * $FreeBSD: releng/11.2/sys/sys/aio.h 331722 2018-03-29 02:50:57Z eadler $
   17  */
   18 
   19 #ifndef _SYS_AIO_H_
   20 #define _SYS_AIO_H_
   21 
   22 #include <sys/types.h>
   23 #include <sys/signal.h>
   24 #ifdef _KERNEL
   25 #include <sys/queue.h>
   26 #include <sys/event.h>
   27 #include <sys/signalvar.h>
   28 #endif
   29 
   30 /*
   31  * Returned by aio_cancel:
   32  */
   33 #define AIO_CANCELED            0x1
   34 #define AIO_NOTCANCELED         0x2
   35 #define AIO_ALLDONE             0x3
   36 
   37 /*
   38  * LIO opcodes
   39  */
   40 #define LIO_NOP                 0x0
   41 #define LIO_WRITE               0x1
   42 #define LIO_READ                0x2
   43 #ifdef _KERNEL
   44 #define LIO_SYNC                0x3
   45 #define LIO_MLOCK               0x4
   46 #endif
   47 
   48 /*
   49  * LIO modes
   50  */
   51 #define LIO_NOWAIT              0x0
   52 #define LIO_WAIT                0x1
   53 
   54 /*
   55  * Maximum number of operations in a single lio_listio call
   56  */
   57 #define AIO_LISTIO_MAX          16
   58 
   59 #ifdef _KERNEL
   60 
   61 /* Default values of tunables for the AIO worker pool. */
   62 
   63 #ifndef MAX_AIO_PROCS
   64 #define MAX_AIO_PROCS           32
   65 #endif
   66 
   67 #ifndef TARGET_AIO_PROCS
   68 #define TARGET_AIO_PROCS        4
   69 #endif
   70 
   71 #ifndef AIOD_LIFETIME_DEFAULT
   72 #define AIOD_LIFETIME_DEFAULT   (30 * hz)
   73 #endif
   74 
   75 #endif
   76 
   77 /*
   78  * Private members for aiocb -- don't access
   79  * directly.
   80  */
   81 struct __aiocb_private {
   82         long    status;
   83         long    error;
   84         void    *kernelinfo;
   85 };
   86 
   87 /*
   88  * I/O control block
   89  */
   90 typedef struct aiocb {
   91         int     aio_fildes;             /* File descriptor */
   92         off_t   aio_offset;             /* File offset for I/O */
   93         volatile void *aio_buf;         /* I/O buffer in process space */
   94         size_t  aio_nbytes;             /* Number of bytes for I/O */
   95         int     __spare__[2];
   96         void    *__spare2__;
   97         int     aio_lio_opcode;         /* LIO opcode */
   98         int     aio_reqprio;            /* Request priority -- ignored */
   99         struct  __aiocb_private _aiocb_private;
  100         struct  sigevent aio_sigevent;  /* Signal to deliver */
  101 } aiocb_t;
  102 
  103 #ifdef _KERNEL
  104 
  105 typedef void aio_cancel_fn_t(struct kaiocb *);
  106 typedef void aio_handle_fn_t(struct kaiocb *);
  107 
  108 /*
  109  * Kernel version of an I/O control block.
  110  *
  111  * Locking key:
  112  * * - need not protected
  113  * a - locked by kaioinfo lock
  114  * b - locked by backend lock
  115  * c - locked by aio_job_mtx
  116  */
  117 struct kaiocb {
  118         TAILQ_ENTRY(kaiocb) list;       /* (b) backend-specific list of jobs */
  119         TAILQ_ENTRY(kaiocb) plist;      /* (a) lists of pending / done jobs */
  120         TAILQ_ENTRY(kaiocb) allist;     /* (a) list of all jobs in proc */
  121         int     jobflags;               /* (a) job flags */
  122         int     inblock;                /* (*) input blocks */
  123         int     outblock;               /* (*) output blocks */
  124         int     msgsnd;                 /* (*) messages sent */
  125         int     msgrcv;                 /* (*) messages received */
  126         struct  proc *userproc;         /* (*) user process */
  127         struct  ucred *cred;            /* (*) active credential when created */
  128         struct  file *fd_file;          /* (*) pointer to file structure */
  129         struct  aioliojob *lio;         /* (*) optional lio job */
  130         struct  aiocb *ujob;            /* (*) pointer in userspace of aiocb */
  131         struct  knlist klist;           /* (a) list of knotes */
  132         struct  aiocb uaiocb;           /* (*) copy of user I/O control block */
  133         ksiginfo_t ksi;                 /* (a) realtime signal info */
  134         uint64_t seqno;                 /* (*) job number */
  135         aio_cancel_fn_t *cancel_fn;     /* (a) backend cancel function */
  136         aio_handle_fn_t *handle_fn;     /* (c) backend handle function */
  137         union {                         /* Backend-specific data fields */
  138                 struct {                /* BIO backend */
  139                         struct bio *bp; /* (*) BIO pointer */
  140                         struct buf *pbuf; /* (*) buffer pointer */
  141                         struct vm_page *pages[btoc(MAXPHYS)+1]; /* (*) */
  142                         int     npages; /* (*) number of pages */
  143                 };
  144                 struct {                /* fsync() requests */
  145                         int     pending; /* (a) number of pending I/O */
  146                 };
  147                 struct {
  148                         void    *backend1;
  149                         void    *backend2;
  150                         long    backend3;
  151                         int     backend4;
  152                 };
  153         };
  154 };
  155 
  156 struct socket;
  157 struct sockbuf;
  158 
  159 /*
  160  * AIO backends should permit cancellation of queued requests waiting to
  161  * be serviced by installing a cancel routine while the request is
  162  * queued.  The cancellation routine should dequeue the request if
  163  * necessary and cancel it.  Care must be used to handle races between
  164  * queueing and dequeueing requests and cancellation.
  165  *
  166  * When queueing a request somewhere such that it can be cancelled, the
  167  * caller should:
  168  *
  169  *  1) Acquire lock that protects the associated queue.
  170  *  2) Call aio_set_cancel_function() to install the cancel routine.
  171  *  3) If that fails, the request has a pending cancel and should be
  172  *     cancelled via aio_cancel().
  173  *  4) Queue the request.
  174  *
  175  * When dequeueing a request to service it or hand it off to somewhere else,
  176  * the caller should:
  177  *
  178  *  1) Acquire the lock that protects the associated queue.
  179  *  2) Dequeue the request.
  180  *  3) Call aio_clear_cancel_function() to clear the cancel routine.
  181  *  4) If that fails, the cancel routine is about to be called.  The
  182  *     caller should ignore the request.
  183  *
  184  * The cancel routine should:
  185  *
  186  *  1) Acquire the lock that protects the associated queue.
  187  *  2) Call aio_cancel_cleared() to determine if the request is already
  188  *     dequeued due to a race with dequeueing thread.
  189  *  3) If that fails, dequeue the request.
  190  *  4) Cancel the request via aio_cancel().
  191  */
  192 
  193 bool    aio_cancel_cleared(struct kaiocb *job);
  194 void    aio_cancel(struct kaiocb *job);
  195 bool    aio_clear_cancel_function(struct kaiocb *job);
  196 void    aio_complete(struct kaiocb *job, long status, int error);
  197 void    aio_schedule(struct kaiocb *job, aio_handle_fn_t *func);
  198 bool    aio_set_cancel_function(struct kaiocb *job, aio_cancel_fn_t *func);
  199 void    aio_switch_vmspace(struct kaiocb *job);
  200 
  201 #else /* !_KERNEL */
  202 
  203 struct timespec;
  204 
  205 __BEGIN_DECLS
  206 /*
  207  * Asynchronously read from a file
  208  */
  209 int     aio_read(struct aiocb *);
  210 
  211 /*
  212  * Asynchronously write to file
  213  */
  214 int     aio_write(struct aiocb *);
  215 
  216 /*
  217  * List I/O Asynchronously/synchronously read/write to/from file
  218  *      "lio_mode" specifies whether or not the I/O is synchronous.
  219  *      "acb_list" is an array of "nacb_listent" I/O control blocks.
  220  *      when all I/Os are complete, the optional signal "sig" is sent.
  221  */
  222 int     lio_listio(int, struct aiocb *__restrict const *__restrict, int,
  223     struct sigevent *);
  224 
  225 /*
  226  * Get completion status
  227  *      returns EINPROGRESS until I/O is complete.
  228  *      this routine does not block.
  229  */
  230 int     aio_error(const struct aiocb *);
  231 
  232 /*
  233  * Finish up I/O, releasing I/O resources and returns the value
  234  *      that would have been associated with a synchronous I/O request.
  235  *      This routine must be called once and only once for each
  236  *      I/O control block who has had I/O associated with it.
  237  */
  238 ssize_t aio_return(struct aiocb *);
  239 
  240 /*
  241  * Cancel I/O
  242  */
  243 int     aio_cancel(int, struct aiocb *);
  244 
  245 /*
  246  * Suspend until all specified I/O or timeout is complete.
  247  */
  248 int     aio_suspend(const struct aiocb * const[], int, const struct timespec *);
  249 
  250 /*
  251  * Asynchronous mlock
  252  */
  253 int     aio_mlock(struct aiocb *);
  254 
  255 #if __BSD_VISIBLE
  256 ssize_t aio_waitcomplete(struct aiocb **, struct timespec *);
  257 #endif
  258 
  259 int     aio_fsync(int op, struct aiocb *aiocbp);
  260 __END_DECLS
  261 
  262 #endif /* !_KERNEL */
  263 
  264 #endif /* !_SYS_AIO_H_ */

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