1 /* $NetBSD: bufq_disksort.c,v 1.9 2008/04/30 12:09:02 reinoud 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_disksort.c,v 1.9 2008/04/30 12:09:02 reinoud 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/malloc.h>
79
80 /*
81 * Seek sort for disks.
82 *
83 * There are actually two queues, sorted in ascendening order. The first
84 * queue holds those requests which are positioned after the current block;
85 * the second holds requests which came in after their position was passed.
86 * Thus we implement a one-way scan, retracting after reaching the end of
87 * the drive to the first request on the second queue, at which time it
88 * becomes the first queue.
89 *
90 * A one-way scan is natural because of the way UNIX read-ahead blocks are
91 * allocated.
92 */
93
94 struct bufq_disksort {
95 TAILQ_HEAD(, buf) bq_head; /* actual list of buffers */
96 };
97
98 static void bufq_disksort_init(struct bufq_state *);
99 static void bufq_disksort_put(struct bufq_state *, struct buf *);
100 static struct buf *bufq_disksort_get(struct bufq_state *, int);
101
102 BUFQ_DEFINE(disksort, 20, bufq_disksort_init);
103
104 static void
105 bufq_disksort_put(struct bufq_state *bufq, struct buf *bp)
106 {
107 struct bufq_disksort *disksort = bufq_private(bufq);
108 struct buf *bq, *nbq;
109 int sortby;
110
111 sortby = bufq->bq_flags & BUFQ_SORT_MASK;
112
113 bq = TAILQ_FIRST(&disksort->bq_head);
114
115 /*
116 * If the queue is empty it's easy; we just go on the end.
117 */
118 if (bq == NULL) {
119 TAILQ_INSERT_TAIL(&disksort->bq_head, bp, b_actq);
120 return;
121 }
122
123 /*
124 * If we lie before the currently active request, then we
125 * must locate the second request list and add ourselves to it.
126 */
127 if (buf_inorder(bp, bq, sortby)) {
128 while ((nbq = TAILQ_NEXT(bq, b_actq)) != NULL) {
129 /*
130 * Check for an ``inversion'' in the normally ascending
131 * block numbers, indicating the start of the second
132 * request list.
133 */
134 if (buf_inorder(nbq, bq, sortby)) {
135 /*
136 * Search the second request list for the first
137 * request at a larger block number. We go
138 * after that; if there is no such request, we
139 * go at the end.
140 */
141 do {
142 if (buf_inorder(bp, nbq, sortby))
143 goto insert;
144 bq = nbq;
145 } while ((nbq =
146 TAILQ_NEXT(bq, b_actq)) != NULL);
147 goto insert; /* after last */
148 }
149 bq = nbq;
150 }
151 /*
152 * No inversions... we will go after the last, and
153 * be the first request in the second request list.
154 */
155 goto insert;
156 }
157 /*
158 * Request is at/after the current request...
159 * sort in the first request list.
160 */
161 while ((nbq = TAILQ_NEXT(bq, b_actq)) != NULL) {
162 /*
163 * We want to go after the current request if there is an
164 * inversion after it (i.e. it is the end of the first
165 * request list), or if the next request is a larger cylinder
166 * than our request.
167 */
168 if (buf_inorder(nbq, bq, sortby) ||
169 buf_inorder(bp, nbq, sortby))
170 goto insert;
171 bq = nbq;
172 }
173 /*
174 * Neither a second list nor a larger request... we go at the end of
175 * the first list, which is the same as the end of the whole schebang.
176 */
177 insert: TAILQ_INSERT_AFTER(&disksort->bq_head, bq, bp, b_actq);
178 }
179
180 static struct buf *
181 bufq_disksort_get(struct bufq_state *bufq, int remove)
182 {
183 struct bufq_disksort *disksort = bufq->bq_private;
184 struct buf *bp;
185
186 bp = TAILQ_FIRST(&disksort->bq_head);
187
188 if (bp != NULL && remove)
189 TAILQ_REMOVE(&disksort->bq_head, bp, b_actq);
190
191 return (bp);
192 }
193
194 static struct buf *
195 bufq_disksort_cancel(struct bufq_state *bufq, struct buf *buf)
196 {
197 struct bufq_disksort *disksort = bufq->bq_private;
198 struct buf *bq;
199
200 bq = TAILQ_FIRST(&disksort->bq_head);
201 while (bq) {
202 if (bq == buf) {
203 TAILQ_REMOVE(&disksort->bq_head, bq, b_actq);
204 return buf;
205 }
206 bq = TAILQ_NEXT(bq, b_actq);
207 }
208 return NULL;
209 }
210
211 static void
212 bufq_disksort_init(struct bufq_state *bufq)
213 {
214 struct bufq_disksort *disksort;
215
216 disksort = malloc(sizeof(*disksort), M_DEVBUF, M_ZERO);
217 bufq->bq_private = disksort;
218 bufq->bq_get = bufq_disksort_get;
219 bufq->bq_put = bufq_disksort_put;
220 bufq->bq_cancel = bufq_disksort_cancel;
221 TAILQ_INIT(&disksort->bq_head);
222 }
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