pseudofs_vncache.c

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    1 /*-
    2  * Copyright (c) 2001 Dag-Erling Coïdan Smørgrav
    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  *    in this position and unchanged.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  * 3. The name of the author may not be used to endorse or promote products
   15  *    derived from this software without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   27  *
   28  *      $FreeBSD: releng/5.1/sys/fs/pseudofs/pseudofs_vncache.c 112564 2003-03-24 21:15:35Z jhb $
   29  */
   30 
   31 #include <sys/param.h>
   32 #include <sys/kernel.h>
   33 #include <sys/systm.h>
   34 #include <sys/eventhandler.h>
   35 #include <sys/lock.h>
   36 #include <sys/malloc.h>
   37 #include <sys/mutex.h>
   38 #include <sys/proc.h>
   39 #include <sys/sysctl.h>
   40 #include <sys/vnode.h>
   41 
   42 #include <fs/pseudofs/pseudofs.h>
   43 #include <fs/pseudofs/pseudofs_internal.h>
   44 
   45 static MALLOC_DEFINE(M_PFSVNCACHE, "pfs_vncache", "pseudofs vnode cache");
   46 
   47 static struct mtx pfs_vncache_mutex;
   48 static struct pfs_vdata *pfs_vncache;
   49 static eventhandler_tag pfs_exit_tag;
   50 static void pfs_exit(void *arg, struct proc *p);
   51 
   52 SYSCTL_NODE(_vfs_pfs, OID_AUTO, vncache, CTLFLAG_RW, 0,
   53     "pseudofs vnode cache");
   54 
   55 static int pfs_vncache_entries;
   56 SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, entries, CTLFLAG_RD,
   57     &pfs_vncache_entries, 0,
   58     "number of entries in the vnode cache");
   59 
   60 static int pfs_vncache_maxentries;
   61 SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, maxentries, CTLFLAG_RD,
   62     &pfs_vncache_maxentries, 0,
   63     "highest number of entries in the vnode cache");
   64 
   65 static int pfs_vncache_hits;
   66 SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, hits, CTLFLAG_RD,
   67     &pfs_vncache_hits, 0,
   68     "number of cache hits since initialization");
   69 
   70 static int pfs_vncache_misses;
   71 SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, misses, CTLFLAG_RD,
   72     &pfs_vncache_misses, 0,
   73     "number of cache misses since initialization");
   74 
   75 extern vop_t **pfs_vnodeop_p;
   76 
   77 /*
   78  * Initialize vnode cache
   79  */
   80 void
   81 pfs_vncache_load(void)
   82 {
   83         mtx_init(&pfs_vncache_mutex, "pseudofs_vncache", NULL,
   84             MTX_DEF | MTX_RECURSE);
   85         pfs_exit_tag = EVENTHANDLER_REGISTER(process_exit, pfs_exit, NULL,
   86             EVENTHANDLER_PRI_ANY);
   87 }
   88 
   89 /*
   90  * Tear down vnode cache
   91  */
   92 void
   93 pfs_vncache_unload(void)
   94 {
   95         EVENTHANDLER_DEREGISTER(process_exit, pfs_exit_tag);
   96         if (pfs_vncache_entries != 0)
   97                 printf("pfs_vncache_unload(): %d entries remaining\n",
   98                     pfs_vncache_entries);
   99         mtx_destroy(&pfs_vncache_mutex);
  100 }
  101 
  102 /*
  103  * Allocate a vnode
  104  */
  105 int
  106 pfs_vncache_alloc(struct mount *mp, struct vnode **vpp,
  107                   struct pfs_node *pn, pid_t pid)
  108 {
  109         struct pfs_vdata *pvd;
  110         int error;
  111 
  112         /*
  113          * See if the vnode is in the cache.
  114          * XXX linear search is not very efficient.
  115          */
  116         mtx_lock(&pfs_vncache_mutex);
  117         for (pvd = pfs_vncache; pvd; pvd = pvd->pvd_next) {
  118                 if (pvd->pvd_pn == pn && pvd->pvd_pid == pid &&
  119                     pvd->pvd_vnode->v_mount == mp) {
  120                         if (vget(pvd->pvd_vnode, 0, curthread) == 0) {
  121                                 ++pfs_vncache_hits;
  122                                 *vpp = pvd->pvd_vnode;
  123                                 mtx_unlock(&pfs_vncache_mutex);
  124                                 /* XXX see comment at top of pfs_lookup() */
  125                                 cache_purge(*vpp);
  126                                 vn_lock(*vpp, LK_RETRY | LK_EXCLUSIVE,
  127                                     curthread);
  128                                 return (0);
  129                         }
  130                         /* XXX if this can happen, we're in trouble */
  131                         break;
  132                 }
  133         }
  134         mtx_unlock(&pfs_vncache_mutex);
  135         ++pfs_vncache_misses;
  136 
  137         /* nope, get a new one */
  138         MALLOC(pvd, struct pfs_vdata *, sizeof *pvd, M_PFSVNCACHE, M_WAITOK);
  139         if (++pfs_vncache_entries > pfs_vncache_maxentries)
  140                 pfs_vncache_maxentries = pfs_vncache_entries;
  141         error = getnewvnode("pseudofs", mp, pfs_vnodeop_p, vpp);
  142         if (error) {
  143                 FREE(pvd, M_PFSVNCACHE);
  144                 return (error);
  145         }
  146         pvd->pvd_pn = pn;
  147         pvd->pvd_pid = pid;
  148         (*vpp)->v_data = pvd;
  149         switch (pn->pn_type) {
  150         case pfstype_root:
  151                 (*vpp)->v_vflag = VV_ROOT;
  152 #if 0
  153                 printf("root vnode allocated\n");
  154 #endif
  155                 /* fall through */
  156         case pfstype_dir:
  157         case pfstype_this:
  158         case pfstype_parent:
  159         case pfstype_procdir:
  160                 (*vpp)->v_type = VDIR;
  161                 break;
  162         case pfstype_file:
  163                 (*vpp)->v_type = VREG;
  164                 break;
  165         case pfstype_symlink:
  166                 (*vpp)->v_type = VLNK;
  167                 break;
  168         case pfstype_none:
  169                 KASSERT(0, ("pfs_vncache_alloc called for null node\n"));
  170         default:
  171                 panic("%s has unexpected type: %d", pn->pn_name, pn->pn_type);
  172         }
  173         /*
  174          * Propagate flag through to vnode so users know it can change
  175          * if the process changes (i.e. execve)
  176          */
  177         if ((pn->pn_flags & PFS_PROCDEP) != 0)
  178                 (*vpp)->v_vflag |= VV_PROCDEP;
  179         pvd->pvd_vnode = *vpp;
  180         mtx_lock(&pfs_vncache_mutex);
  181         pvd->pvd_prev = NULL;
  182         pvd->pvd_next = pfs_vncache;
  183         if (pvd->pvd_next)
  184                 pvd->pvd_next->pvd_prev = pvd;
  185         pfs_vncache = pvd;
  186         mtx_unlock(&pfs_vncache_mutex);
  187         (*vpp)->v_vnlock->lk_flags |= LK_CANRECURSE;
  188         vn_lock(*vpp, LK_RETRY | LK_EXCLUSIVE, curthread);
  189         return (0);
  190 }
  191 
  192 /*
  193  * Free a vnode
  194  */
  195 int
  196 pfs_vncache_free(struct vnode *vp)
  197 {
  198         struct pfs_vdata *pvd;
  199 
  200         cache_purge(vp);
  201 
  202         mtx_lock(&pfs_vncache_mutex);
  203         pvd = (struct pfs_vdata *)vp->v_data;
  204         KASSERT(pvd != NULL, ("pfs_vncache_free(): no vnode data\n"));
  205         if (pvd->pvd_next)
  206                 pvd->pvd_next->pvd_prev = pvd->pvd_prev;
  207         if (pvd->pvd_prev)
  208                 pvd->pvd_prev->pvd_next = pvd->pvd_next;
  209         else
  210                 pfs_vncache = pvd->pvd_next;
  211         mtx_unlock(&pfs_vncache_mutex);
  212 
  213         --pfs_vncache_entries;
  214         FREE(pvd, M_PFSVNCACHE);
  215         vp->v_data = NULL;
  216         return (0);
  217 }
  218 
  219 /*
  220  * Free all vnodes associated with a defunct process
  221  */
  222 static void
  223 pfs_exit(void *arg, struct proc *p)
  224 {
  225         struct pfs_vdata *pvd, *prev;
  226 
  227         mtx_lock(&pfs_vncache_mutex);
  228         /*
  229          * The double loop is necessary because vgone() indirectly
  230          * calls pfs_vncache_free() which frees pvd, so we have to
  231          * backtrace one step every time we free a vnode.
  232          */
  233         /* XXX linear search... not very efficient */
  234         for (pvd = pfs_vncache; pvd != NULL; pvd = pvd->pvd_next) {
  235                 while (pvd != NULL && pvd->pvd_pid == p->p_pid) {
  236                         prev = pvd->pvd_prev;
  237                         vgone(pvd->pvd_vnode);
  238                         pvd = prev ? prev->pvd_next : pfs_vncache;
  239                 }
  240                 if (pvd == NULL)
  241                         break;
  242         }
  243         mtx_unlock(&pfs_vncache_mutex);
  244 }
  245 
  246 /*
  247  * Disable a pseudofs node, and free all vnodes associated with it
  248  */
  249 int
  250 pfs_disable(struct pfs_node *pn)
  251 {
  252         struct pfs_vdata *pvd, *prev;
  253 
  254         if (pn->pn_flags & PFS_DISABLED)
  255                 return (0);
  256         mtx_lock(&pfs_vncache_mutex);
  257         pn->pn_flags |= PFS_DISABLED;
  258         /* see the comment about the double loop in pfs_exit() */
  259         /* XXX linear search... not very efficient */
  260         for (pvd = pfs_vncache; pvd != NULL; pvd = pvd->pvd_next) {
  261                 while (pvd != NULL && pvd->pvd_pn == pn) {
  262                         prev = pvd->pvd_prev;
  263                         vgone(pvd->pvd_vnode);
  264                         pvd = prev ? prev->pvd_next : pfs_vncache;
  265                 }
  266                 if (pvd == NULL)
  267                         break;
  268         }
  269         mtx_unlock(&pfs_vncache_mutex);
  270         return (0);
  271 }
  272 
  273 /*
  274  * Re-enable a disabled pseudofs node
  275  */
  276 int
  277 pfs_enable(struct pfs_node *pn)
  278 {
  279         pn->pn_flags &= ~PFS_DISABLED;
  280         return (0);
  281 }

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FreeBSD/Linux Kernel Cross Reference sys/fs/pseudofs/pseudofs_vncache.c

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sys/fs/pseudofs/pseudofs_vncache.c