FreeBSD/Linux Kernel Cross Reference
sys/kern/bufq_fcfs.c
1 /* $NetBSD: bufq_fcfs.c,v 1.3 2004/11/25 04:52:24 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 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by the NetBSD
23 * Foundation, Inc. and its contributors.
24 * 4. Neither the name of The NetBSD Foundation nor the names of its
25 * contributors may be used to endorse or promote products derived
26 * from this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
29 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
30 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
31 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
32 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
33 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
34 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
35 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
36 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
37 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
38 * POSSIBILITY OF SUCH DAMAGE.
39 */
40
41 /*
42 * Copyright (c) 1982, 1986, 1988, 1993
43 * The Regents of the University of California. All rights reserved.
44 * (c) UNIX System Laboratories, Inc.
45 * All or some portions of this file are derived from material licensed
46 * to the University of California by American Telephone and Telegraph
47 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
48 * the permission of UNIX System Laboratories, Inc.
49 *
50 * Redistribution and use in source and binary forms, with or without
51 * modification, are permitted provided that the following conditions
52 * are met:
53 * 1. Redistributions of source code must retain the above copyright
54 * notice, this list of conditions and the following disclaimer.
55 * 2. Redistributions in binary form must reproduce the above copyright
56 * notice, this list of conditions and the following disclaimer in the
57 * documentation and/or other materials provided with the distribution.
58 * 3. Neither the name of the University nor the names of its contributors
59 * may be used to endorse or promote products derived from this software
60 * without specific prior written permission.
61 *
62 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
63 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
64 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
65 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
66 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
67 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
68 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
69 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
70 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
71 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
72 * SUCH DAMAGE.
73 *
74 * @(#)ufs_disksubr.c 8.5 (Berkeley) 1/21/94
75 */
76
77 #include <sys/cdefs.h>
78 __KERNEL_RCSID(0, "$NetBSD: bufq_fcfs.c,v 1.3 2004/11/25 04:52:24 yamt Exp $");
79
80 #include <sys/param.h>
81 #include <sys/systm.h>
82 #include <sys/buf.h>
83 #include <sys/bufq.h>
84 #include <sys/malloc.h>
85
86 /*
87 * First-come first-served sort for disks.
88 *
89 * Requests are appended to the queue without any reordering.
90 */
91
92 struct bufq_fcfs {
93 TAILQ_HEAD(, buf) bq_head; /* actual list of buffers */
94 };
95
96 static void bufq_fcfs_init(struct bufq_state *);
97 static void bufq_fcfs_put(struct bufq_state *, struct buf *);
98 static struct buf *bufq_fcfs_get(struct bufq_state *, int);
99
100 BUFQ_DEFINE(fcfs, BUFQ_FCFS, bufq_fcfs_init);
101
102 static void
103 bufq_fcfs_put(struct bufq_state *bufq, struct buf *bp)
104 {
105 struct bufq_fcfs *fcfs = bufq->bq_private;
106
107 TAILQ_INSERT_TAIL(&fcfs->bq_head, bp, b_actq);
108 }
109
110 static struct buf *
111 bufq_fcfs_get(struct bufq_state *bufq, int remove)
112 {
113 struct bufq_fcfs *fcfs = bufq->bq_private;
114 struct buf *bp;
115
116 bp = TAILQ_FIRST(&fcfs->bq_head);
117
118 if (bp != NULL && remove)
119 TAILQ_REMOVE(&fcfs->bq_head, bp, b_actq);
120
121 return (bp);
122 }
123
124 static void
125 bufq_fcfs_init(struct bufq_state *bufq)
126 {
127 struct bufq_fcfs *fcfs;
128
129 bufq->bq_get = bufq_fcfs_get;
130 bufq->bq_put = bufq_fcfs_put;
131 MALLOC(bufq->bq_private, struct bufq_fcfs *,
132 sizeof(struct bufq_fcfs), M_DEVBUF, M_ZERO);
133 fcfs = (struct bufq_fcfs *)bufq->bq_private;
134 TAILQ_INIT(&fcfs->bq_head);
135 }
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