sys/kern/bufq_fcfs.c

   1 /*      $NetBSD: bufq_fcfs.c,v 1.9 2009/01/16 01:48:09 yamt Exp $       */
   2 /*      NetBSD: subr_disk.c,v 1.61 2004/09/25 03:30:44 thorpej Exp      */
   3
   4 /*-
   5  * Copyright (c) 1996, 1997, 1999, 2000 The NetBSD Foundation, Inc.
   6  * All rights reserved.
   7  *
   8  * This code is derived from software contributed to The NetBSD Foundation
   9  * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
  10  * NASA Ames Research Center.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  23  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  24  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  25  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  26  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  27  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  28  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  29  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  30  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  31  * POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 /*
  35  * Copyright (c) 1982, 1986, 1988, 1993
  36  *      The Regents of the University of California.  All rights reserved.
  37  * (c) UNIX System Laboratories, Inc.
  38  * All or some portions of this file are derived from material licensed
  39  * to the University of California by American Telephone and Telegraph
  40  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
  41  * the permission of UNIX System Laboratories, Inc.
  42  *
  43  * Redistribution and use in source and binary forms, with or without
  44  * modification, are permitted provided that the following conditions
  45  * are met:
  46  * 1. Redistributions of source code must retain the above copyright
  47  *    notice, this list of conditions and the following disclaimer.
  48  * 2. Redistributions in binary form must reproduce the above copyright
  49  *    notice, this list of conditions and the following disclaimer in the
  50  *    documentation and/or other materials provided with the distribution.
  51  * 3. Neither the name of the University nor the names of its contributors
  52  *    may be used to endorse or promote products derived from this software
  53  *    without specific prior written permission.
  54  *
  55  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  56  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  57  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  58  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  59  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  60  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  61  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  62  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  63  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  64  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  65  * SUCH DAMAGE.
  66  *
  67  *      @(#)ufs_disksubr.c      8.5 (Berkeley) 1/21/94
  68  */
  69
  70 #include <sys/cdefs.h>
  71 __KERNEL_RCSID(0, "$NetBSD: bufq_fcfs.c,v 1.9 2009/01/16 01:48:09 yamt Exp $");
  72
  73 #include <sys/param.h>
  74 #include <sys/systm.h>
  75 #include <sys/buf.h>
  76 #include <sys/bufq.h>
  77 #include <sys/bufq_impl.h>
  78 #include <sys/kmem.h>
  79
  80 /*
  81  * First-come first-served sort for disks.
  82  *
  83  * Requests are appended to the queue without any reordering.
  84  */
  85
  86 struct bufq_fcfs {
  87         TAILQ_HEAD(, buf) bq_head;      /* actual list of buffers */
  88 };
  89
  90 static void bufq_fcfs_init(struct bufq_state *);
  91 static void bufq_fcfs_put(struct bufq_state *, struct buf *);
  92 static struct buf *bufq_fcfs_get(struct bufq_state *, int);
  93
  94 BUFQ_DEFINE(fcfs, 10, bufq_fcfs_init);
  95
  96 static void
  97 bufq_fcfs_put(struct bufq_state *bufq, struct buf *bp)
  98 {
  99         struct bufq_fcfs *fcfs = bufq->bq_private;
 100
 101         TAILQ_INSERT_TAIL(&fcfs->bq_head, bp, b_actq);
 102 }
 103
 104 static struct buf *
 105 bufq_fcfs_get(struct bufq_state *bufq, int remove)
 106 {
 107         struct bufq_fcfs *fcfs = bufq->bq_private;
 108         struct buf *bp;
 109
 110         bp = TAILQ_FIRST(&fcfs->bq_head);
 111
 112         if (bp != NULL && remove)
 113                 TAILQ_REMOVE(&fcfs->bq_head, bp, b_actq);
 114
 115         return (bp);
 116 }
 117
 118 static struct buf *
 119 bufq_fcfs_cancel(struct bufq_state *bufq, struct buf *buf)
 120 {
 121         struct bufq_fcfs *fcfs = bufq->bq_private;
 122         struct buf *bp;
 123
 124         TAILQ_FOREACH(bp, &fcfs->bq_head, b_actq) {
 125                 if (bp == buf) {
 126                         TAILQ_REMOVE(&fcfs->bq_head, bp, b_actq);
 127                         return buf;
 128                 }
 129         }
 130         return NULL;
 131 }
 132
 133 static void
 134 bufq_fcfs_fini(struct bufq_state *bufq)
 135 {
 136
 137         KASSERT(bufq->bq_private != NULL);
 138         kmem_free(bufq->bq_private, sizeof(struct bufq_fcfs));
 139 }
 140
 141 static void
 142 bufq_fcfs_init(struct bufq_state *bufq)
 143 {
 144         struct bufq_fcfs *fcfs;
 145
 146         bufq->bq_get = bufq_fcfs_get;
 147         bufq->bq_put = bufq_fcfs_put;
 148         bufq->bq_cancel = bufq_fcfs_cancel;
 149         bufq->bq_fini = bufq_fcfs_fini;
 150         bufq->bq_private = kmem_zalloc(sizeof(struct bufq_fcfs), KM_SLEEP);
 151         fcfs = (struct bufq_fcfs *)bufq->bq_private;
 152         TAILQ_INIT(&fcfs->bq_head);
 153 }