1 /* $NetBSD: bufq_disksort.c,v 1.14 2017/05/04 11:03:27 kamil 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 1.14 2017/05/04 11:03:27 kamil 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 #include <sys/module.h> 80 81 /* 82 * Seek sort for disks. 83 * 84 * There are actually two queues, sorted in ascendening order. The first 85 * queue holds those requests which are positioned after the current block; 86 * the second holds requests which came in after their position was passed. 87 * Thus we implement a one-way scan, retracting after reaching the end of 88 * the drive to the first request on the second queue, at which time it 89 * becomes the first queue. 90 * 91 * A one-way scan is natural because of the way UNIX read-ahead blocks are 92 * allocated. 93 */ 94 95 struct bufq_disksort { 96 TAILQ_HEAD(, buf) bq_head; /* actual list of buffers */ 97 }; 98 99 static void bufq_disksort_init(struct bufq_state *); 100 static void bufq_disksort_put(struct bufq_state *, struct buf *); 101 static struct buf *bufq_disksort_get(struct bufq_state *, int); 102 103 BUFQ_DEFINE(disksort, 20, bufq_disksort_init); 104 105 static void 106 bufq_disksort_put(struct bufq_state *bufq, struct buf *bp) 107 { 108 struct bufq_disksort *disksort = bufq_private(bufq); 109 struct buf *bq, *nbq; 110 int sortby; 111 112 sortby = bufq->bq_flags & BUFQ_SORT_MASK; 113 114 bq = TAILQ_FIRST(&disksort->bq_head); 115 116 /* 117 * If the queue is empty it's easy; we just go on the end. 118 */ 119 if (bq == NULL) { 120 TAILQ_INSERT_TAIL(&disksort->bq_head, bp, b_actq); 121 return; 122 } 123 124 /* 125 * If we lie before the currently active request, then we 126 * must locate the second request list and add ourselves to it. 127 */ 128 if (buf_inorder(bp, bq, sortby)) { 129 while ((nbq = TAILQ_NEXT(bq, b_actq)) != NULL) { 130 /* 131 * Check for an ``inversion'' in the normally ascending 132 * block numbers, indicating the start of the second 133 * request list. 134 */ 135 if (buf_inorder(nbq, bq, sortby)) { 136 /* 137 * Search the second request list for the first 138 * request at a larger block number. We go 139 * after that; if there is no such request, we 140 * go at the end. 141 */ 142 do { 143 if (buf_inorder(bp, nbq, sortby)) 144 goto insert; 145 bq = nbq; 146 } while ((nbq = 147 TAILQ_NEXT(bq, b_actq)) != NULL); 148 goto insert; /* after last */ 149 } 150 bq = nbq; 151 } 152 /* 153 * No inversions... we will go after the last, and 154 * be the first request in the second request list. 155 */ 156 goto insert; 157 } 158 /* 159 * Request is at/after the current request... 160 * sort in the first request list. 161 */ 162 while ((nbq = TAILQ_NEXT(bq, b_actq)) != NULL) { 163 /* 164 * We want to go after the current request if there is an 165 * inversion after it (i.e. it is the end of the first 166 * request list), or if the next request is a larger cylinder 167 * than our request. 168 */ 169 if (buf_inorder(nbq, bq, sortby) || 170 buf_inorder(bp, nbq, sortby)) 171 goto insert; 172 bq = nbq; 173 } 174 /* 175 * Neither a second list nor a larger request... we go at the end of 176 * the first list, which is the same as the end of the whole schebang. 177 */ 178 insert: TAILQ_INSERT_AFTER(&disksort->bq_head, bq, bp, b_actq); 179 } 180 181 static struct buf * 182 bufq_disksort_get(struct bufq_state *bufq, int remove) 183 { 184 struct bufq_disksort *disksort = bufq_private(bufq); 185 struct buf *bp; 186 187 bp = TAILQ_FIRST(&disksort->bq_head); 188 189 if (bp != NULL && remove) 190 TAILQ_REMOVE(&disksort->bq_head, bp, b_actq); 191 192 return (bp); 193 } 194 195 static struct buf * 196 bufq_disksort_cancel(struct bufq_state *bufq, struct buf *buf) 197 { 198 struct bufq_disksort *disksort = bufq_private(bufq); 199 struct buf *bq; 200 201 TAILQ_FOREACH(bq, &disksort->bq_head, b_actq) { 202 if (bq == buf) { 203 TAILQ_REMOVE(&disksort->bq_head, bq, b_actq); 204 return buf; 205 } 206 } 207 return NULL; 208 } 209 210 static void 211 bufq_disksort_fini(struct bufq_state *bufq) 212 { 213 214 KASSERT(bufq->bq_private != NULL); 215 kmem_free(bufq->bq_private, sizeof(struct bufq_disksort)); 216 } 217 218 static void 219 bufq_disksort_init(struct bufq_state *bufq) 220 { 221 struct bufq_disksort *disksort; 222 223 disksort = kmem_zalloc(sizeof(*disksort), KM_SLEEP); 224 bufq->bq_private = disksort; 225 bufq->bq_get = bufq_disksort_get; 226 bufq->bq_put = bufq_disksort_put; 227 bufq->bq_cancel = bufq_disksort_cancel; 228 bufq->bq_fini = bufq_disksort_fini; 229 TAILQ_INIT(&disksort->bq_head); 230 } 231 232 MODULE(MODULE_CLASS_BUFQ, bufq_disksort, NULL); 233 234 static int 235 bufq_disksort_modcmd(modcmd_t cmd, void *opaque) 236 { 237 238 switch (cmd) { 239 case MODULE_CMD_INIT: 240 return bufq_register(&bufq_strat_disksort); 241 case MODULE_CMD_FINI: 242 return bufq_unregister(&bufq_strat_disksort); 243 default: 244 return ENOTTY; 245 } 246 } 247
Indexes created Mon Sep 22 05:09:51 GMT 2025