subr_bufq.c revision 1.18 
1/*	$NetBSD: subr_bufq.c,v 1.18 2009/01/19 14:54:28 yamt 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 1.18 2009/01/19 14:54:28 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#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 = kmem_zalloc(sizeof(*bufq), KM_SLEEP);
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
180struct buf *
181bufq_cancel(struct bufq_state *bufq, struct buf *bp)
182{
183
184	return (*bufq->bq_cancel)(bufq, bp);
185}
186
187/*
188 * Drain a device buffer queue.
189 */
190void
191bufq_drain(struct bufq_state *bufq)
192{
193	struct buf *bp;
194
195	while ((bp = bufq_get(bufq)) != NULL) {
196		bp->b_error = EIO;
197		bp->b_resid = bp->b_bcount;
198		biodone(bp);
199	}
200}
201
202/*
203 * Destroy a device buffer queue.
204 */
205void
206bufq_free(struct bufq_state *bufq)
207{
208
209	KASSERT(bufq_peek(bufq) == NULL);
210
211	bufq->bq_fini(bufq);
212	kmem_free(bufq, sizeof(*bufq));
213}
214
215/*
216 * get a strategy identifier of a buffer queue.
217 */
218const char *
219bufq_getstrategyname(struct bufq_state *bufq)
220{
221
222	return bufq->bq_strat->bs_name;
223}
224
225/*
226 * move all requests on a buffer queue to another.
227 */
228void
229bufq_move(struct bufq_state *dst, struct bufq_state *src)
230{
231	struct buf *bp;
232
233	while ((bp = bufq_get(src)) != NULL) {
234		bufq_put(dst, bp);
235	}
236}
237
238static int
239docopy(char *buf, size_t *bufoffp, size_t buflen,
240    const char *datap, size_t datalen)
241{
242	int error = 0;
243
244	if (buf != NULL && datalen > 0) {
245
246		if (*bufoffp + datalen > buflen) {
247			goto out;
248		}
249		error = copyout(datap, buf + *bufoffp, datalen);
250		if (error) {
251			goto out;
252		}
253	}
254out:
255	if (error == 0) {
256		*bufoffp += datalen;
257	}
258
259	return error;
260}
261
262static int
263docopystr(char *buf, size_t *bufoffp, size_t buflen, const char *datap)
264{
265
266	return docopy(buf, bufoffp, buflen, datap, strlen(datap));
267}
268
269static int
270docopynul(char *buf, size_t *bufoffp, size_t buflen)
271{
272
273	return docopy(buf, bufoffp, buflen, "", 1);
274}
275
276/*
277 * sysctl function that will print all bufq strategies
278 * built in the kernel.
279 */
280static int
281sysctl_kern_bufq_strategies(SYSCTLFN_ARGS)
282{
283	__link_set_decl(bufq_strats, const struct bufq_strat);
284	const struct bufq_strat * const *bq_strat;
285	const char *delim = "";
286	size_t off = 0;
287	size_t buflen = *oldlenp;
288	int error;
289
290	__link_set_foreach(bq_strat, bufq_strats) {
291		if ((*bq_strat) == &bufq_strat_dummy) {
292			continue;
293		}
294		error = docopystr(oldp, &off, buflen, delim);
295		if (error) {
296			goto out;
297		}
298		error = docopystr(oldp, &off, buflen, (*bq_strat)->bs_name);
299		if (error) {
300			goto out;
301		}
302		delim = " ";
303	}
304
305	/* NUL terminate */
306	error = docopynul(oldp, &off, buflen);
307out:
308	*oldlenp = off;
309	return error;
310}
311
312SYSCTL_SETUP(sysctl_kern_bufq_strategies_setup, "sysctl kern.bufq tree setup")
313{
314	const struct sysctlnode *node;
315
316	sysctl_createv(clog, 0, NULL, NULL,
317			CTLFLAG_PERMANENT,
318			CTLTYPE_NODE, "kern", NULL,
319			NULL, 0, NULL, 0,
320			CTL_KERN, CTL_EOL);
321	node = NULL;
322	sysctl_createv(clog, 0, NULL, &node,
323			CTLFLAG_PERMANENT,
324			CTLTYPE_NODE, "bufq",
325			SYSCTL_DESCR("buffer queue subtree"),
326			NULL, 0, NULL, 0,
327			CTL_KERN, CTL_CREATE, CTL_EOL);
328	if (node != NULL) {
329		sysctl_createv(clog, 0, NULL, NULL,
330			CTLFLAG_PERMANENT,
331			CTLTYPE_STRING, "strategies",
332			SYSCTL_DESCR("List of bufq strategies present"),
333			sysctl_kern_bufq_strategies, 0, NULL, 0,
334			CTL_KERN, node->sysctl_num, CTL_CREATE, CTL_EOL);
335	}
336}
337