subr_bufq.c

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    1 /*      $NetBSD: subr_bufq.c,v 1.27 2019/02/17 23:17:41 bad 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 1.27 2019/02/17 23:17:41 bad 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 #include <sys/module.h>
   81 
   82 #define STRAT_MATCH(id, bs)     (strcmp((id), (bs)->bs_name) == 0)
   83 
   84 static void sysctl_kern_bufq_strategies_setup(struct sysctllog **);
   85 static SLIST_HEAD(, bufq_strat) bufq_strat_list =
   86     SLIST_HEAD_INITIALIZER(bufq_strat_list);
   87 
   88 static kmutex_t bufq_mutex;
   89 
   90 static struct sysctllog *sysctllog;
   91 
   92 void
   93 bufq_init(void)
   94 {
   95 
   96         mutex_init(&bufq_mutex, MUTEX_DEFAULT, IPL_NONE);
   97         sysctl_kern_bufq_strategies_setup(&sysctllog);
   98 }
   99 
  100 int
  101 bufq_register(struct bufq_strat *bs)
  102 {
  103 
  104         mutex_enter(&bufq_mutex);
  105         SLIST_INSERT_HEAD(&bufq_strat_list, bs, bs_next);
  106         bs->bs_refcnt = 0;
  107         mutex_exit(&bufq_mutex);
  108 
  109         return 0;
  110 }
  111 
  112 int
  113 bufq_unregister(struct bufq_strat *bs)
  114 {
  115 
  116         mutex_enter(&bufq_mutex);
  117         if (bs->bs_refcnt != 0) {
  118                 mutex_exit(&bufq_mutex);
  119                 return EBUSY;
  120         }
  121         SLIST_REMOVE(&bufq_strat_list, bs, bufq_strat, bs_next);
  122         mutex_exit(&bufq_mutex);
  123 
  124         return 0;
  125 }
  126 
  127 /*
  128  * Create a device buffer queue.
  129  */
  130 int
  131 bufq_alloc(struct bufq_state **bufqp, const char *strategy, int flags)
  132 {
  133         struct bufq_strat *bsp, *it;
  134         struct bufq_state *bufq;
  135         int error = 0;
  136         u_int gen;
  137         bool found_exact;
  138         char strategy_module_name[MAXPATHLEN];
  139 
  140         KASSERT((flags & BUFQ_EXACT) == 0 || strategy != BUFQ_STRAT_ANY);
  141 
  142         switch (flags & BUFQ_SORT_MASK) {
  143         case BUFQ_SORT_RAWBLOCK:
  144         case BUFQ_SORT_CYLINDER:
  145                 break;
  146         case 0:
  147                 /*
  148                  * for strategies which don't care about block numbers.
  149                  * eg. fcfs
  150                  */
  151                 flags |= BUFQ_SORT_RAWBLOCK;
  152                 break;
  153         default:
  154                 panic("bufq_alloc: sort out of range");
  155         }
  156 
  157         /*
  158          * select strategy.
  159          * if a strategy specified by flags is found, use it.
  160          * otherwise, select one with the largest bs_prio.
  161          */
  162         mutex_enter(&bufq_mutex);
  163         do {
  164                 gen = module_gen;
  165                 bsp = NULL;
  166                 found_exact = false;
  167 
  168                 SLIST_FOREACH(it, &bufq_strat_list, bs_next) {
  169                         if (strategy != BUFQ_STRAT_ANY &&
  170                             STRAT_MATCH(strategy, (it))) {
  171                                 bsp = it;
  172                                 found_exact = true;
  173                                 break;
  174                         }
  175                         if (bsp == NULL || (it)->bs_prio > bsp->bs_prio)
  176                                 bsp = it;
  177                 }
  178                 if (strategy == BUFQ_STRAT_ANY || found_exact)
  179                         break;
  180 
  181                 /* Try to autoload the bufq strategy module */
  182                 strlcpy(strategy_module_name, "bufq_",
  183                         sizeof(strategy_module_name));
  184                 strlcat(strategy_module_name, strategy,
  185                         sizeof(strategy_module_name));
  186                 mutex_exit(&bufq_mutex);
  187                 (void) module_autoload(strategy_module_name, MODULE_CLASS_BUFQ);
  188                 mutex_enter(&bufq_mutex);
  189         } while (gen != module_gen);
  190 
  191         if (bsp == NULL) {
  192                 panic("bufq_alloc: no strategy");
  193         }
  194         if (strategy != BUFQ_STRAT_ANY && !found_exact) {
  195                 if ((flags & BUFQ_EXACT)) {
  196                         error = ENOENT;
  197                         mutex_exit(&bufq_mutex);
  198                         goto out;
  199                 }
  200 #if defined(DEBUG)
  201                 printf("bufq_alloc: '%s' is not available. using '%s'.\n",
  202                     strategy, bsp->bs_name);
  203 #endif
  204         }
  205 #if defined(BUFQ_DEBUG)
  206         /* XXX aprint? */
  207         printf("bufq_alloc: using '%s'\n", bsp->bs_name);
  208 #endif
  209 
  210         bsp->bs_refcnt++;
  211         mutex_exit(&bufq_mutex);
  212         *bufqp = bufq = kmem_zalloc(sizeof(*bufq), KM_SLEEP);
  213         bufq->bq_flags = flags;
  214         bufq->bq_strat = bsp;
  215         (*bsp->bs_initfn)(bufq);
  216 
  217 out:
  218         return error;
  219 }
  220 
  221 void
  222 bufq_put(struct bufq_state *bufq, struct buf *bp)
  223 {
  224 
  225         (*bufq->bq_put)(bufq, bp);
  226 }
  227 
  228 struct buf *
  229 bufq_get(struct bufq_state *bufq)
  230 {
  231 
  232         return (*bufq->bq_get)(bufq, 1);
  233 }
  234 
  235 struct buf *
  236 bufq_peek(struct bufq_state *bufq)
  237 {
  238 
  239         return (*bufq->bq_get)(bufq, 0);
  240 }
  241 
  242 struct buf *
  243 bufq_cancel(struct bufq_state *bufq, struct buf *bp)
  244 {
  245 
  246         return (*bufq->bq_cancel)(bufq, bp);
  247 }
  248 
  249 /*
  250  * Drain a device buffer queue.
  251  */
  252 void
  253 bufq_drain(struct bufq_state *bufq)
  254 {
  255         struct buf *bp;
  256 
  257         while ((bp = bufq_get(bufq)) != NULL) {
  258                 bp->b_error = EIO;
  259                 bp->b_resid = bp->b_bcount;
  260                 biodone(bp);
  261         }
  262 }
  263 
  264 /*
  265  * Destroy a device buffer queue.
  266  */
  267 void
  268 bufq_free(struct bufq_state *bufq)
  269 {
  270 
  271         KASSERT(bufq_peek(bufq) == NULL);
  272 
  273         bufq->bq_fini(bufq);
  274 
  275         mutex_enter(&bufq_mutex);
  276         bufq->bq_strat->bs_refcnt--;
  277         mutex_exit(&bufq_mutex);
  278         
  279         kmem_free(bufq, sizeof(*bufq));
  280 }
  281 
  282 /*
  283  * get a strategy identifier of a buffer queue.
  284  */
  285 const char *
  286 bufq_getstrategyname(struct bufq_state *bufq)
  287 {
  288 
  289         return bufq->bq_strat->bs_name;
  290 }
  291 
  292 /*
  293  * move all requests on a buffer queue to another.
  294  */
  295 void
  296 bufq_move(struct bufq_state *dst, struct bufq_state *src)
  297 {
  298         struct buf *bp;
  299 
  300         while ((bp = bufq_get(src)) != NULL) {
  301                 bufq_put(dst, bp);
  302         }
  303 }
  304 
  305 static int
  306 docopy(char *buf, size_t *bufoffp, size_t buflen,
  307     const char *datap, size_t datalen)
  308 {
  309         int error = 0;
  310 
  311         if (buf != NULL && datalen > 0) {
  312 
  313                 if (*bufoffp + datalen > buflen) {
  314                         goto out;
  315                 }
  316                 error = copyout(datap, buf + *bufoffp, datalen);
  317                 if (error) {
  318                         goto out;
  319                 }
  320         }
  321 out:
  322         if (error == 0) {
  323                 *bufoffp += datalen;
  324         }
  325 
  326         return error;
  327 }
  328 
  329 static int
  330 docopystr(char *buf, size_t *bufoffp, size_t buflen, const char *datap)
  331 {
  332 
  333         return docopy(buf, bufoffp, buflen, datap, strlen(datap));
  334 }
  335 
  336 static int
  337 docopynul(char *buf, size_t *bufoffp, size_t buflen)
  338 {
  339 
  340         return docopy(buf, bufoffp, buflen, "", 1);
  341 }
  342 
  343 /*
  344  * sysctl function that will print all bufq strategies
  345  * currently available to the kernel.
  346  */
  347 static int
  348 sysctl_kern_bufq_strategies(SYSCTLFN_ARGS)
  349 {
  350         const struct bufq_strat *bq_strat;
  351         const char *delim = "";
  352         size_t off = 0;
  353         size_t buflen = *oldlenp;
  354         int error;
  355 
  356         SLIST_FOREACH(bq_strat, &bufq_strat_list, bs_next) {
  357                 error = docopystr(oldp, &off, buflen, delim);
  358                 if (error) {
  359                         goto out;
  360                 }
  361                 error = docopystr(oldp, &off, buflen, (bq_strat)->bs_name);
  362                 if (error) {
  363                         goto out;
  364                 }
  365                 delim = " ";
  366         }
  367 
  368         /* In case there are no registered strategies ... */
  369         if (off == 0) {
  370                 error = docopystr(oldp, &off, buflen, "NULL");
  371                 if (error) {
  372                         goto out;
  373                 }
  374         }
  375 
  376         /* NUL terminate */
  377         error = docopynul(oldp, &off, buflen);
  378 out:
  379         *oldlenp = off;
  380         return error;
  381 }
  382 
  383 static void
  384 sysctl_kern_bufq_strategies_setup(struct sysctllog **clog)
  385 {
  386         const struct sysctlnode *node;
  387 
  388         node = NULL;
  389         sysctl_createv(clog, 0, NULL, &node,
  390                         CTLFLAG_PERMANENT,
  391                         CTLTYPE_NODE, "bufq",
  392                         SYSCTL_DESCR("buffer queue subtree"),
  393                         NULL, 0, NULL, 0,
  394                         CTL_KERN, CTL_CREATE, CTL_EOL);
  395         if (node != NULL) {
  396                 sysctl_createv(clog, 0, NULL, NULL,
  397                         CTLFLAG_PERMANENT,
  398                         CTLTYPE_STRING, "strategies",
  399                         SYSCTL_DESCR("List of bufq strategies present"),
  400                         sysctl_kern_bufq_strategies, 0, NULL, 0,
  401                         CTL_KERN, node->sysctl_num, CTL_CREATE, CTL_EOL);
  402         }
  403 }
Cache object: b95b43045d4e852b6a6ffae59c512273
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FreeBSD/Linux Kernel Cross Reference sys/kern/subr_bufq.c

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sys/kern/subr_bufq.c
