The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*-
    2  * Copyright (c) 2007 Pawel Jakub Dawidek <pjd@FreeBSD.org>
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD: releng/8.3/sys/kern/kern_osd.c 199583 2009-11-20 15:27:52Z jhb $");
   29 
   30 #include <sys/param.h>
   31 #include <sys/kernel.h>
   32 #include <sys/systm.h>
   33 #include <sys/sysctl.h>
   34 #include <sys/errno.h>
   35 #include <sys/jail.h>
   36 #include <sys/malloc.h>
   37 #include <sys/lock.h>
   38 #include <sys/mutex.h>
   39 #include <sys/rmlock.h>
   40 #include <sys/sx.h>
   41 #include <sys/queue.h>
   42 #include <sys/proc.h>
   43 #include <sys/osd.h>
   44 
   45 /* OSD (Object Specific Data) */
   46 
   47 static MALLOC_DEFINE(M_OSD, "osd", "Object Specific Data");
   48 
   49 static int osd_debug = 0;
   50 TUNABLE_INT("debug.osd", &osd_debug);
   51 SYSCTL_INT(_debug, OID_AUTO, osd, CTLFLAG_RW, &osd_debug, 0, "OSD debug level");
   52 
   53 #define OSD_DEBUG(...)  do {                                            \
   54         if (osd_debug) {                                                \
   55                 printf("OSD (%s:%u): ", __func__, __LINE__);            \
   56                 printf(__VA_ARGS__);                                    \
   57                 printf("\n");                                           \
   58         }                                                               \
   59 } while (0)
   60 
   61 static void do_osd_del(u_int type, struct osd *osd, u_int slot,
   62     int list_locked);
   63 
   64 /*
   65  * Lists of objects with OSD.
   66  *
   67  * Lock key:
   68  *  (m) osd_module_lock
   69  *  (o) osd_object_lock
   70  *  (l) osd_list_lock
   71  */
   72 static LIST_HEAD(, osd) osd_list[OSD_LAST + 1];         /* (m) */
   73 static osd_method_t *osd_methods[OSD_LAST + 1];         /* (m) */
   74 static u_int osd_nslots[OSD_LAST + 1];                  /* (m) */
   75 static osd_destructor_t *osd_destructors[OSD_LAST + 1]; /* (o) */
   76 static const u_int osd_nmethods[OSD_LAST + 1] = {
   77         [OSD_JAIL] = PR_MAXMETHOD,
   78 };
   79 
   80 static struct sx osd_module_lock[OSD_LAST + 1];
   81 static struct rmlock osd_object_lock[OSD_LAST + 1];
   82 static struct mtx osd_list_lock[OSD_LAST + 1];
   83 
   84 static void
   85 osd_default_destructor(void *value __unused)
   86 {
   87         /* Do nothing. */
   88 }
   89 
   90 int
   91 osd_register(u_int type, osd_destructor_t destructor, osd_method_t *methods)
   92 {
   93         void *newptr;
   94         u_int i, m;
   95 
   96         KASSERT(type >= OSD_FIRST && type <= OSD_LAST, ("Invalid type."));
   97 
   98         /*
   99          * If no destructor is given, use default one. We need to use some
  100          * destructor, because NULL destructor means unused slot.
  101          */
  102         if (destructor == NULL)
  103                 destructor = osd_default_destructor;
  104 
  105         sx_xlock(&osd_module_lock[type]);
  106         /*
  107          * First, we try to find unused slot.
  108          */
  109         for (i = 0; i < osd_nslots[type]; i++) {
  110                 if (osd_destructors[type][i] == NULL) {
  111                         OSD_DEBUG("Unused slot found (type=%u, slot=%u).",
  112                             type, i);
  113                         break;
  114                 }
  115         }
  116         /*
  117          * If no unused slot was found, allocate one.
  118          */
  119         if (i == osd_nslots[type]) {
  120                 osd_nslots[type]++;
  121                 if (osd_nmethods[type] != 0)
  122                         osd_methods[type] = realloc(osd_methods[type],
  123                             sizeof(osd_method_t) * osd_nslots[type] *
  124                             osd_nmethods[type], M_OSD, M_WAITOK);
  125                 newptr = malloc(sizeof(osd_destructor_t) * osd_nslots[type],
  126                     M_OSD, M_WAITOK);
  127                 rm_wlock(&osd_object_lock[type]);
  128                 bcopy(osd_destructors[type], newptr,
  129                     sizeof(osd_destructor_t) * i);
  130                 free(osd_destructors[type], M_OSD);
  131                 osd_destructors[type] = newptr;
  132                 rm_wunlock(&osd_object_lock[type]);
  133                 OSD_DEBUG("New slot allocated (type=%u, slot=%u).",
  134                     type, i + 1);
  135         }
  136 
  137         osd_destructors[type][i] = destructor;
  138         if (osd_nmethods[type] != 0) {
  139                 for (m = 0; m < osd_nmethods[type]; m++)
  140                         osd_methods[type][i * osd_nmethods[type] + m] =
  141                             methods != NULL ? methods[m] : NULL;
  142         }
  143         sx_xunlock(&osd_module_lock[type]);
  144         return (i + 1);
  145 }
  146 
  147 void
  148 osd_deregister(u_int type, u_int slot)
  149 {
  150         struct osd *osd, *tosd;
  151 
  152         KASSERT(type >= OSD_FIRST && type <= OSD_LAST, ("Invalid type."));
  153         KASSERT(slot > 0, ("Invalid slot."));
  154         KASSERT(osd_destructors[type][slot - 1] != NULL, ("Unused slot."));
  155 
  156         sx_xlock(&osd_module_lock[type]);
  157         rm_wlock(&osd_object_lock[type]);
  158         /*
  159          * Free all OSD for the given slot.
  160          */
  161         mtx_lock(&osd_list_lock[type]);
  162         LIST_FOREACH_SAFE(osd, &osd_list[type], osd_next, tosd)
  163                 do_osd_del(type, osd, slot, 1);
  164         mtx_unlock(&osd_list_lock[type]);
  165         /*
  166          * Set destructor to NULL to free the slot.
  167          */
  168         osd_destructors[type][slot - 1] = NULL;
  169         if (slot == osd_nslots[type]) {
  170                 osd_nslots[type]--;
  171                 osd_destructors[type] = realloc(osd_destructors[type],
  172                     sizeof(osd_destructor_t) * osd_nslots[type], M_OSD,
  173                     M_NOWAIT | M_ZERO);
  174                 if (osd_nmethods[type] != 0)
  175                         osd_methods[type] = realloc(osd_methods[type],
  176                             sizeof(osd_method_t) * osd_nslots[type] *
  177                             osd_nmethods[type], M_OSD, M_NOWAIT | M_ZERO);
  178                 /*
  179                  * We always reallocate to smaller size, so we assume it will
  180                  * always succeed.
  181                  */
  182                 KASSERT(osd_destructors[type] != NULL &&
  183                     (osd_nmethods[type] == 0 || osd_methods[type] != NULL),
  184                     ("realloc() failed"));
  185                 OSD_DEBUG("Deregistration of the last slot (type=%u, slot=%u).",
  186                     type, slot);
  187         } else {
  188                 OSD_DEBUG("Slot deregistration (type=%u, slot=%u).",
  189                     type, slot);
  190         }
  191         rm_wunlock(&osd_object_lock[type]);
  192         sx_xunlock(&osd_module_lock[type]);
  193 }
  194 
  195 int
  196 osd_set(u_int type, struct osd *osd, u_int slot, void *value)
  197 {
  198         struct rm_priotracker tracker;
  199 
  200         KASSERT(type >= OSD_FIRST && type <= OSD_LAST, ("Invalid type."));
  201         KASSERT(slot > 0, ("Invalid slot."));
  202         KASSERT(osd_destructors[type][slot - 1] != NULL, ("Unused slot."));
  203 
  204         rm_rlock(&osd_object_lock[type], &tracker);
  205         if (slot > osd->osd_nslots) {
  206                 if (value == NULL) {
  207                         OSD_DEBUG(
  208                             "Not allocating null slot (type=%u, slot=%u).",
  209                             type, slot);
  210                         rm_runlock(&osd_object_lock[type], &tracker);
  211                         return (0);
  212                 } else if (osd->osd_nslots == 0) {
  213                         /*
  214                          * First OSD for this object, so we need to allocate
  215                          * space and put it onto the list.
  216                          */
  217                         osd->osd_slots = malloc(sizeof(void *) * slot, M_OSD,
  218                             M_NOWAIT | M_ZERO);
  219                         if (osd->osd_slots == NULL) {
  220                                 rm_runlock(&osd_object_lock[type], &tracker);
  221                                 return (ENOMEM);
  222                         }
  223                         osd->osd_nslots = slot;
  224                         mtx_lock(&osd_list_lock[type]);
  225                         LIST_INSERT_HEAD(&osd_list[type], osd, osd_next);
  226                         mtx_unlock(&osd_list_lock[type]);
  227                         OSD_DEBUG("Setting first slot (type=%u).", type);
  228                 } else {
  229                         void *newptr;
  230 
  231                         /*
  232                          * Too few slots allocated here, needs to extend
  233                          * the array.
  234                          */
  235                         newptr = realloc(osd->osd_slots, sizeof(void *) * slot,
  236                             M_OSD, M_NOWAIT | M_ZERO);
  237                         if (newptr == NULL) {
  238                                 rm_runlock(&osd_object_lock[type], &tracker);
  239                                 return (ENOMEM);
  240                         }
  241                         osd->osd_slots = newptr;
  242                         osd->osd_nslots = slot;
  243                         OSD_DEBUG("Growing slots array (type=%u).", type);
  244                 }
  245         }
  246         OSD_DEBUG("Setting slot value (type=%u, slot=%u, value=%p).", type,
  247             slot, value);
  248         osd->osd_slots[slot - 1] = value;
  249         rm_runlock(&osd_object_lock[type], &tracker);
  250         return (0);
  251 }
  252 
  253 void *
  254 osd_get(u_int type, struct osd *osd, u_int slot)
  255 {
  256         struct rm_priotracker tracker;
  257         void *value;
  258 
  259         KASSERT(type >= OSD_FIRST && type <= OSD_LAST, ("Invalid type."));
  260         KASSERT(slot > 0, ("Invalid slot."));
  261         KASSERT(osd_destructors[type][slot - 1] != NULL, ("Unused slot."));
  262 
  263         rm_rlock(&osd_object_lock[type], &tracker);
  264         if (slot > osd->osd_nslots) {
  265                 value = NULL;
  266                 OSD_DEBUG("Slot doesn't exist (type=%u, slot=%u).", type, slot);
  267         } else {
  268                 value = osd->osd_slots[slot - 1];
  269                 OSD_DEBUG("Returning slot value (type=%u, slot=%u, value=%p).",
  270                     type, slot, value);
  271         }
  272         rm_runlock(&osd_object_lock[type], &tracker);
  273         return (value);
  274 }
  275 
  276 void
  277 osd_del(u_int type, struct osd *osd, u_int slot)
  278 {
  279         struct rm_priotracker tracker;
  280 
  281         rm_rlock(&osd_object_lock[type], &tracker);
  282         do_osd_del(type, osd, slot, 0);
  283         rm_runlock(&osd_object_lock[type], &tracker);
  284 }
  285 
  286 static void
  287 do_osd_del(u_int type, struct osd *osd, u_int slot, int list_locked)
  288 {
  289         int i;
  290 
  291         KASSERT(type >= OSD_FIRST && type <= OSD_LAST, ("Invalid type."));
  292         KASSERT(slot > 0, ("Invalid slot."));
  293         KASSERT(osd_destructors[type][slot - 1] != NULL, ("Unused slot."));
  294 
  295         OSD_DEBUG("Deleting slot (type=%u, slot=%u).", type, slot);
  296 
  297         if (slot > osd->osd_nslots) {
  298                 OSD_DEBUG("Slot doesn't exist (type=%u, slot=%u).", type, slot);
  299                 return;
  300         }
  301         if (osd->osd_slots[slot - 1] != NULL) {
  302                 osd_destructors[type][slot - 1](osd->osd_slots[slot - 1]);
  303                 osd->osd_slots[slot - 1] = NULL;
  304         }
  305         for (i = osd->osd_nslots - 1; i >= 0; i--) {
  306                 if (osd->osd_slots[i] != NULL) {
  307                         OSD_DEBUG("Slot still has a value (type=%u, slot=%u).",
  308                             type, i + 1);
  309                         break;
  310                 }
  311         }
  312         if (i == -1) {
  313                 /* No values left for this object. */
  314                 OSD_DEBUG("No more slots left (type=%u).", type);
  315                 if (!list_locked)
  316                         mtx_lock(&osd_list_lock[type]);
  317                 LIST_REMOVE(osd, osd_next);
  318                 if (!list_locked)
  319                         mtx_unlock(&osd_list_lock[type]);
  320                 free(osd->osd_slots, M_OSD);
  321                 osd->osd_slots = NULL;
  322                 osd->osd_nslots = 0;
  323         } else if (slot == osd->osd_nslots) {
  324                 /* This was the last slot. */
  325                 osd->osd_slots = realloc(osd->osd_slots,
  326                     sizeof(void *) * (i + 1), M_OSD, M_NOWAIT | M_ZERO);
  327                 /*
  328                  * We always reallocate to smaller size, so we assume it will
  329                  * always succeed.
  330                  */
  331                 KASSERT(osd->osd_slots != NULL, ("realloc() failed"));
  332                 osd->osd_nslots = i + 1;
  333                 OSD_DEBUG("Reducing slots array to %u (type=%u).",
  334                     osd->osd_nslots, type);
  335         }
  336 }
  337 
  338 int
  339 osd_call(u_int type, u_int method, void *obj, void *data)
  340 {
  341         osd_method_t methodfun;
  342         int error, i;
  343 
  344         KASSERT(type >= OSD_FIRST && type <= OSD_LAST, ("Invalid type."));
  345         KASSERT(method < osd_nmethods[type], ("Invalid method."));
  346 
  347         /*
  348          * Call this method for every slot that defines it, stopping if an
  349          * error is encountered.
  350          */
  351         error = 0;
  352         sx_slock(&osd_module_lock[type]);
  353         for (i = 0; i < osd_nslots[type]; i++) {
  354                 methodfun =
  355                     osd_methods[type][i * osd_nmethods[type] + method];
  356                 if (methodfun != NULL && (error = methodfun(obj, data)) != 0)
  357                         break;
  358         }
  359         sx_sunlock(&osd_module_lock[type]);
  360         return (error);
  361 }
  362 
  363 void
  364 osd_exit(u_int type, struct osd *osd)
  365 {
  366         struct rm_priotracker tracker;
  367         u_int i;
  368 
  369         KASSERT(type >= OSD_FIRST && type <= OSD_LAST, ("Invalid type."));
  370 
  371         if (osd->osd_nslots == 0) {
  372                 KASSERT(osd->osd_slots == NULL, ("Non-null osd_slots."));
  373                 /* No OSD attached, just leave. */
  374                 return;
  375         }
  376 
  377         rm_rlock(&osd_object_lock[type], &tracker);
  378         for (i = 1; i <= osd->osd_nslots; i++) {
  379                 if (osd_destructors[type][i - 1] != NULL)
  380                         do_osd_del(type, osd, i, 0);
  381                 else
  382                         OSD_DEBUG("Unused slot (type=%u, slot=%u).", type, i);
  383         }
  384         rm_runlock(&osd_object_lock[type], &tracker);
  385         OSD_DEBUG("Object exit (type=%u).", type);
  386 }
  387 
  388 static void
  389 osd_init(void *arg __unused)
  390 {
  391         u_int i;
  392 
  393         for (i = OSD_FIRST; i <= OSD_LAST; i++) {
  394                 osd_nslots[i] = 0;
  395                 LIST_INIT(&osd_list[i]);
  396                 sx_init(&osd_module_lock[i], "osd_module");
  397                 rm_init(&osd_object_lock[i], "osd_object");
  398                 mtx_init(&osd_list_lock[i], "osd_list", NULL, MTX_DEF);
  399                 osd_destructors[i] = NULL;
  400                 osd_methods[i] = NULL;
  401         }
  402 }
  403 SYSINIT(osd, SI_SUB_LOCK, SI_ORDER_ANY, osd_init, NULL);

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