subr_bufq.c

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    1 /*      $NetBSD: subr_bufq.c,v 1.12 2005/12/26 10:36:47 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  * 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: subr_bufq.c,v 1.12 2005/12/26 10:36:47 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/bufq_impl.h>
   85 #include <sys/malloc.h>
   86 #include <sys/sysctl.h>
   87 
   88 BUFQ_DEFINE(dummy, 0, NULL); /* so that bufq_strats won't be empty */
   89 
   90 #define STRAT_MATCH(id, bs)     (strcmp((id), (bs)->bs_name) == 0)
   91 
   92 /*
   93  * Create a device buffer queue.
   94  */
   95 int
   96 bufq_alloc(struct bufq_state **bufqp, const char *strategy, int flags)
   97 {
   98         __link_set_decl(bufq_strats, const struct bufq_strat);
   99         const struct bufq_strat *bsp;
  100         const struct bufq_strat * const *it;
  101         struct bufq_state *bufq;
  102         int error = 0;
  103 
  104         KASSERT((flags & BUFQ_EXACT) == 0 || strategy != BUFQ_STRAT_ANY);
  105 
  106         switch (flags & BUFQ_SORT_MASK) {
  107         case BUFQ_SORT_RAWBLOCK:
  108         case BUFQ_SORT_CYLINDER:
  109                 break;
  110         case 0:
  111                 /*
  112                  * for strategies which don't care about block numbers.
  113                  * eg. fcfs
  114                  */
  115                 flags |= BUFQ_SORT_RAWBLOCK;
  116                 break;
  117         default:
  118                 panic("bufq_alloc: sort out of range");
  119         }
  120 
  121         /*
  122          * select strategy.
  123          * if a strategy specified by flags is found, use it.
  124          * otherwise, select one with the largest bs_prio.
  125          */
  126         bsp = NULL;
  127         __link_set_foreach(it, bufq_strats) {
  128                 if ((*it) == &bufq_strat_dummy)
  129                         continue;
  130                 if (strategy != BUFQ_STRAT_ANY &&
  131                     STRAT_MATCH(strategy, (*it))) {
  132                         bsp = *it;
  133                         break;
  134                 }
  135                 if (bsp == NULL || (*it)->bs_prio > bsp->bs_prio)
  136                         bsp = *it;
  137         }
  138 
  139         if (bsp == NULL) {
  140                 panic("bufq_alloc: no strategy");
  141         }
  142         if (strategy != BUFQ_STRAT_ANY && !STRAT_MATCH(strategy, bsp)) {
  143                 if ((flags & BUFQ_EXACT)) {
  144                         error = ENOENT;
  145                         goto out;
  146                 }
  147 #if defined(DEBUG)
  148                 printf("bufq_alloc: '%s' is not available. using '%s'.\n",
  149                     strategy, bsp->bs_name);
  150 #endif
  151         }
  152 #if defined(BUFQ_DEBUG)
  153         /* XXX aprint? */
  154         printf("bufq_alloc: using '%s'\n", bsp->bs_name);
  155 #endif
  156 
  157         *bufqp = bufq = malloc(sizeof(*bufq), M_DEVBUF, M_WAITOK | M_ZERO);
  158         bufq->bq_flags = flags;
  159         bufq->bq_strat = bsp;
  160         (*bsp->bs_initfn)(bufq);
  161 
  162 out:
  163         return error;
  164 }
  165 
  166 void
  167 bufq_put(struct bufq_state *bufq, struct buf *bp)
  168 {
  169 
  170         (*bufq->bq_put)(bufq, bp);
  171 }
  172 
  173 struct buf *
  174 bufq_get(struct bufq_state *bufq)
  175 {
  176 
  177         return (*bufq->bq_get)(bufq, 1);
  178 }
  179 
  180 struct buf *
  181 bufq_peek(struct bufq_state *bufq)
  182 {
  183 
  184         return (*bufq->bq_get)(bufq, 0);
  185 }
  186 
  187 /*
  188  * Drain a device buffer queue.
  189  */
  190 void
  191 bufq_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_flags |= B_ERROR;
  198                 bp->b_resid = bp->b_bcount;
  199                 biodone(bp);
  200         }
  201 }
  202 
  203 /*
  204  * Destroy a device buffer queue.
  205  */
  206 void
  207 bufq_free(struct bufq_state *bufq)
  208 {
  209 
  210         KASSERT(bufq->bq_private != NULL);
  211         KASSERT(BUFQ_PEEK(bufq) == NULL);
  212 
  213         free(bufq->bq_private, M_DEVBUF);
  214         free(bufq, M_DEVBUF);
  215 }
  216 
  217 /*
  218  * get a strategy identifier of a buffer queue.
  219  */
  220 const char *
  221 bufq_getstrategyname(struct bufq_state *bufq)
  222 {
  223 
  224         return bufq->bq_strat->bs_name;
  225 }
  226 
  227 /*
  228  * move all requests on a buffer queue to another.
  229  */
  230 void
  231 bufq_move(struct bufq_state *dst, struct bufq_state *src)
  232 {
  233         struct buf *bp;
  234 
  235         while ((bp = BUFQ_GET(src)) != NULL) {
  236                 BUFQ_PUT(dst, bp);
  237         }
  238 }
  239 
  240 static int
  241 docopy(char *buf, size_t *bufoffp, size_t buflen,
  242     const char *datap, size_t datalen)
  243 {
  244         int error = 0;
  245 
  246         if (buf != NULL && datalen > 0) {
  247 
  248                 if (*bufoffp + datalen > buflen) {
  249                         goto out;
  250                 }
  251                 error = copyout(datap, buf + *bufoffp, datalen);
  252                 if (error) {
  253                         goto out;
  254                 }
  255         }
  256 out:
  257         if (error == 0) {
  258                 *bufoffp += datalen;
  259         }
  260 
  261         return error;
  262 }
  263 
  264 static int
  265 docopystr(char *buf, size_t *bufoffp, size_t buflen, const char *datap)
  266 {
  267 
  268         return docopy(buf, bufoffp, buflen, datap, strlen(datap));
  269 }
  270 
  271 static int
  272 docopynul(char *buf, size_t *bufoffp, size_t buflen)
  273 {
  274 
  275         return docopy(buf, bufoffp, buflen, "", 1);
  276 }
  277 
  278 /*
  279  * sysctl function that will print all bufq strategies
  280  * built in the kernel.
  281  */
  282 static int
  283 sysctl_kern_bufq_strategies(SYSCTLFN_ARGS)
  284 {
  285         __link_set_decl(bufq_strats, const struct bufq_strat);
  286         const struct bufq_strat * const *bq_strat;
  287         const char *delim = "";
  288         size_t off = 0;
  289         size_t buflen = *oldlenp;
  290         int error;
  291 
  292         __link_set_foreach(bq_strat, bufq_strats) {
  293                 if ((*bq_strat) == &bufq_strat_dummy) {
  294                         continue;
  295                 }
  296                 error = docopystr(oldp, &off, buflen, delim);
  297                 if (error) {
  298                         goto out;
  299                 }
  300                 error = docopystr(oldp, &off, buflen, (*bq_strat)->bs_name);
  301                 if (error) {
  302                         goto out;
  303                 }
  304                 delim = " ";
  305         }
  306 
  307         /* NUL terminate */
  308         error = docopynul(oldp, &off, buflen);
  309 out:
  310         *oldlenp = off;
  311         return error;
  312 }
  313 
  314 SYSCTL_SETUP(sysctl_kern_bufq_strategies_setup, "sysctl kern.bufq tree setup")
  315 {
  316         const struct sysctlnode *node;
  317 
  318         sysctl_createv(clog, 0, NULL, NULL,
  319                         CTLFLAG_PERMANENT,
  320                         CTLTYPE_NODE, "kern", NULL,
  321                         NULL, 0, NULL, 0,
  322                         CTL_KERN, CTL_EOL);
  323         node = NULL;
  324         sysctl_createv(clog, 0, NULL, &node,
  325                         CTLFLAG_PERMANENT,
  326                         CTLTYPE_NODE, "bufq",
  327                         SYSCTL_DESCR("buffer queue subtree"),
  328                         NULL, 0, NULL, 0,
  329                         CTL_KERN, CTL_CREATE, CTL_EOL);
  330         if (node != NULL) {
  331                 sysctl_createv(clog, 0, NULL, NULL,
  332                         CTLFLAG_PERMANENT,
  333                         CTLTYPE_STRING, "strategies",
  334                         SYSCTL_DESCR("List of bufq strategies present"),
  335                         sysctl_kern_bufq_strategies, 0, NULL, 0,
  336                         CTL_KERN, node->sysctl_num, CTL_CREATE, CTL_EOL);
  337         }
  338 }
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FreeBSD/Linux Kernel Cross Reference sys/kern/subr_bufq.c

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sys/kern/subr_bufq.c
