subr_bufq.c revision 1.14 
1/*	$NetBSD: subr_bufq.c,v 1.14 2008/04/28 20:24:04 martin Exp $	*/
2/*	NetBSD: subr_disk.c,v 1.70 2005/08/20 12:00:01 yamt 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: subr_bufq.c,v 1.14 2008/04/28 20:24:04 martin 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#include <sys/sysctl.h>
80
81BUFQ_DEFINE(dummy, 0, NULL); /* so that bufq_strats won't be empty */
82
83#define	STRAT_MATCH(id, bs)	(strcmp((id), (bs)->bs_name) == 0)
84
85/*
86 * Create a device buffer queue.
87 */
88int
89bufq_alloc(struct bufq_state **bufqp, const char *strategy, int flags)
90{
91	__link_set_decl(bufq_strats, const struct bufq_strat);
92	const struct bufq_strat *bsp;
93	const struct bufq_strat * const *it;
94	struct bufq_state *bufq;
95	int error = 0;
96
97	KASSERT((flags & BUFQ_EXACT) == 0 || strategy != BUFQ_STRAT_ANY);
98
99	switch (flags & BUFQ_SORT_MASK) {
100	case BUFQ_SORT_RAWBLOCK:
101	case BUFQ_SORT_CYLINDER:
102		break;
103	case 0:
104		/*
105		 * for strategies which don't care about block numbers.
106		 * eg. fcfs
107		 */
108		flags |= BUFQ_SORT_RAWBLOCK;
109		break;
110	default:
111		panic("bufq_alloc: sort out of range");
112	}
113
114	/*
115	 * select strategy.
116	 * if a strategy specified by flags is found, use it.
117	 * otherwise, select one with the largest bs_prio.
118	 */
119	bsp = NULL;
120	__link_set_foreach(it, bufq_strats) {
121		if ((*it) == &bufq_strat_dummy)
122			continue;
123		if (strategy != BUFQ_STRAT_ANY &&
124		    STRAT_MATCH(strategy, (*it))) {
125			bsp = *it;
126			break;
127		}
128		if (bsp == NULL || (*it)->bs_prio > bsp->bs_prio)
129			bsp = *it;
130	}
131
132	if (bsp == NULL) {
133		panic("bufq_alloc: no strategy");
134	}
135	if (strategy != BUFQ_STRAT_ANY && !STRAT_MATCH(strategy, bsp)) {
136		if ((flags & BUFQ_EXACT)) {
137			error = ENOENT;
138			goto out;
139		}
140#if defined(DEBUG)
141		printf("bufq_alloc: '%s' is not available. using '%s'.\n",
142		    strategy, bsp->bs_name);
143#endif
144	}
145#if defined(BUFQ_DEBUG)
146	/* XXX aprint? */
147	printf("bufq_alloc: using '%s'\n", bsp->bs_name);
148#endif
149
150	*bufqp = bufq = malloc(sizeof(*bufq), M_DEVBUF, M_WAITOK | M_ZERO);
151	bufq->bq_flags = flags;
152	bufq->bq_strat = bsp;
153	(*bsp->bs_initfn)(bufq);
154
155out:
156	return error;
157}
158
159void
160bufq_put(struct bufq_state *bufq, struct buf *bp)
161{
162
163	(*bufq->bq_put)(bufq, bp);
164}
165
166struct buf *
167bufq_get(struct bufq_state *bufq)
168{
169
170	return (*bufq->bq_get)(bufq, 1);
171}
172
173struct buf *
174bufq_peek(struct bufq_state *bufq)
175{
176
177	return (*bufq->bq_get)(bufq, 0);
178}
179
180/*
181 * Drain a device buffer queue.
182 */
183void
184bufq_drain(struct bufq_state *bufq)
185{
186	struct buf *bp;
187
188	while ((bp = BUFQ_GET(bufq)) != NULL) {
189		bp->b_error = EIO;
190		bp->b_resid = bp->b_bcount;
191		biodone(bp);
192	}
193}
194
195/*
196 * Destroy a device buffer queue.
197 */
198void
199bufq_free(struct bufq_state *bufq)
200{
201
202	KASSERT(bufq->bq_private != NULL);
203	KASSERT(BUFQ_PEEK(bufq) == NULL);
204
205	free(bufq->bq_private, M_DEVBUF);
206	free(bufq, M_DEVBUF);
207}
208
209/*
210 * get a strategy identifier of a buffer queue.
211 */
212const char *
213bufq_getstrategyname(struct bufq_state *bufq)
214{
215
216	return bufq->bq_strat->bs_name;
217}
218
219/*
220 * move all requests on a buffer queue to another.
221 */
222void
223bufq_move(struct bufq_state *dst, struct bufq_state *src)
224{
225	struct buf *bp;
226
227	while ((bp = BUFQ_GET(src)) != NULL) {
228		BUFQ_PUT(dst, bp);
229	}
230}
231
232static int
233docopy(char *buf, size_t *bufoffp, size_t buflen,
234    const char *datap, size_t datalen)
235{
236	int error = 0;
237
238	if (buf != NULL && datalen > 0) {
239
240		if (*bufoffp + datalen > buflen) {
241			goto out;
242		}
243		error = copyout(datap, buf + *bufoffp, datalen);
244		if (error) {
245			goto out;
246		}
247	}
248out:
249	if (error == 0) {
250		*bufoffp += datalen;
251	}
252
253	return error;
254}
255
256static int
257docopystr(char *buf, size_t *bufoffp, size_t buflen, const char *datap)
258{
259
260	return docopy(buf, bufoffp, buflen, datap, strlen(datap));
261}
262
263static int
264docopynul(char *buf, size_t *bufoffp, size_t buflen)
265{
266
267	return docopy(buf, bufoffp, buflen, "", 1);
268}
269
270/*
271 * sysctl function that will print all bufq strategies
272 * built in the kernel.
273 */
274static int
275sysctl_kern_bufq_strategies(SYSCTLFN_ARGS)
276{
277	__link_set_decl(bufq_strats, const struct bufq_strat);
278	const struct bufq_strat * const *bq_strat;
279	const char *delim = "";
280	size_t off = 0;
281	size_t buflen = *oldlenp;
282	int error;
283
284	__link_set_foreach(bq_strat, bufq_strats) {
285		if ((*bq_strat) == &bufq_strat_dummy) {
286			continue;
287		}
288		error = docopystr(oldp, &off, buflen, delim);
289		if (error) {
290			goto out;
291		}
292		error = docopystr(oldp, &off, buflen, (*bq_strat)->bs_name);
293		if (error) {
294			goto out;
295		}
296		delim = " ";
297	}
298
299	/* NUL terminate */
300	error = docopynul(oldp, &off, buflen);
301out:
302	*oldlenp = off;
303	return error;
304}
305
306SYSCTL_SETUP(sysctl_kern_bufq_strategies_setup, "sysctl kern.bufq tree setup")
307{
308	const struct sysctlnode *node;
309
310	sysctl_createv(clog, 0, NULL, NULL,
311			CTLFLAG_PERMANENT,
312			CTLTYPE_NODE, "kern", NULL,
313			NULL, 0, NULL, 0,
314			CTL_KERN, CTL_EOL);
315	node = NULL;
316	sysctl_createv(clog, 0, NULL, &node,
317			CTLFLAG_PERMANENT,
318			CTLTYPE_NODE, "bufq",
319			SYSCTL_DESCR("buffer queue subtree"),
320			NULL, 0, NULL, 0,
321			CTL_KERN, CTL_CREATE, CTL_EOL);
322	if (node != NULL) {
323		sysctl_createv(clog, 0, NULL, NULL,
324			CTLFLAG_PERMANENT,
325			CTLTYPE_STRING, "strategies",
326			SYSCTL_DESCR("List of bufq strategies present"),
327			sysctl_kern_bufq_strategies, 0, NULL, 0,
328			CTL_KERN, node->sysctl_num, CTL_CREATE, CTL_EOL);
329	}
330}
331