subr_bufq.c

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    1 /*      $NetBSD: subr_bufq.c,v 1.15 2008/04/30 12:09:02 reinoud 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 1.15 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 #include <sys/sysctl.h>
   80 
   81 BUFQ_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  */
   88 int
   89 bufq_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 
  155 out:
  156         return error;
  157 }
  158 
  159 void
  160 bufq_put(struct bufq_state *bufq, struct buf *bp)
  161 {
  162 
  163         (*bufq->bq_put)(bufq, bp);
  164 }
  165 
  166 struct buf *
  167 bufq_get(struct bufq_state *bufq)
  168 {
  169 
  170         return (*bufq->bq_get)(bufq, 1);
  171 }
  172 
  173 struct buf *
  174 bufq_peek(struct bufq_state *bufq)
  175 {
  176 
  177         return (*bufq->bq_get)(bufq, 0);
  178 }
  179 
  180 struct buf *
  181 bufq_cancel(struct bufq_state *bufq, struct buf *bp)
  182 {
  183         return (*bufq->bq_cancel)(bufq, bp);
  184 }
  185 
  186 /*
  187  * Drain a device buffer queue.
  188  */
  189 void
  190 bufq_drain(struct bufq_state *bufq)
  191 {
  192         struct buf *bp;
  193 
  194         while ((bp = BUFQ_GET(bufq)) != NULL) {
  195                 bp->b_error = EIO;
  196                 bp->b_resid = bp->b_bcount;
  197                 biodone(bp);
  198         }
  199 }
  200 
  201 /*
  202  * Destroy a device buffer queue.
  203  */
  204 void
  205 bufq_free(struct bufq_state *bufq)
  206 {
  207 
  208         KASSERT(bufq->bq_private != NULL);
  209         KASSERT(BUFQ_PEEK(bufq) == NULL);
  210 
  211         free(bufq->bq_private, M_DEVBUF);
  212         free(bufq, M_DEVBUF);
  213 }
  214 
  215 /*
  216  * get a strategy identifier of a buffer queue.
  217  */
  218 const char *
  219 bufq_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  */
  228 void
  229 bufq_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 
  238 static int
  239 docopy(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         }
  254 out:
  255         if (error == 0) {
  256                 *bufoffp += datalen;
  257         }
  258 
  259         return error;
  260 }
  261 
  262 static int
  263 docopystr(char *buf, size_t *bufoffp, size_t buflen, const char *datap)
  264 {
  265 
  266         return docopy(buf, bufoffp, buflen, datap, strlen(datap));
  267 }
  268 
  269 static int
  270 docopynul(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  */
  280 static int
  281 sysctl_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);
  307 out:
  308         *oldlenp = off;
  309         return error;
  310 }
  311 
  312 SYSCTL_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 }
Cache object: ae403ccad50d1909479aea1ae243d2e0
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FreeBSD/Linux Kernel Cross Reference sys/kern/subr_bufq.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_bufq.c
