vfs_cache.c

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    1 /*      $NetBSD: vfs_cache.c,v 1.66.2.1 2007/02/17 23:27:47 tron Exp $  */
    2 
    3 /*
    4  * Copyright (c) 1989, 1993
    5  *      The Regents of the University of California.  All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  * 3. Neither the name of the University nor the names of its contributors
   16  *    may be used to endorse or promote products derived from this software
   17  *    without specific prior written permission.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   29  * SUCH DAMAGE.
   30  *
   31  *      @(#)vfs_cache.c 8.3 (Berkeley) 8/22/94
   32  */
   33 
   34 #include <sys/cdefs.h>
   35 __KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,v 1.66.2.1 2007/02/17 23:27:47 tron Exp $");
   36 
   37 #include "opt_ddb.h"
   38 #include "opt_revcache.h"
   39 
   40 #include <sys/param.h>
   41 #include <sys/systm.h>
   42 #include <sys/time.h>
   43 #include <sys/mount.h>
   44 #include <sys/vnode.h>
   45 #include <sys/namei.h>
   46 #include <sys/errno.h>
   47 #include <sys/malloc.h>
   48 #include <sys/pool.h>
   49 #include <sys/lock.h>
   50 
   51 #define NAMECACHE_ENTER_REVERSE
   52 /*
   53  * Name caching works as follows:
   54  *
   55  * Names found by directory scans are retained in a cache
   56  * for future reference.  It is managed LRU, so frequently
   57  * used names will hang around.  Cache is indexed by hash value
   58  * obtained from (dvp, name) where dvp refers to the directory
   59  * containing name.
   60  *
   61  * For simplicity (and economy of storage), names longer than
   62  * a maximum length of NCHNAMLEN are not cached; they occur
   63  * infrequently in any case, and are almost never of interest.
   64  *
   65  * Upon reaching the last segment of a path, if the reference
   66  * is for DELETE, or NOCACHE is set (rewrite), and the
   67  * name is located in the cache, it will be dropped.
   68  * The entry is dropped also when it was not possible to lock
   69  * the cached vnode, either because vget() failed or the generation
   70  * number has changed while waiting for the lock.
   71  */
   72 
   73 /*
   74  * Structures associated with name cacheing.
   75  */
   76 LIST_HEAD(nchashhead, namecache) *nchashtbl;
   77 u_long  nchash;                         /* size of hash table - 1 */
   78 long    numcache;                       /* number of cache entries allocated */
   79 #define NCHASH(cnp, dvp)        \
   80         (((cnp)->cn_hash ^ ((uintptr_t)(dvp) >> 3)) & nchash)
   81 
   82 LIST_HEAD(ncvhashhead, namecache) *ncvhashtbl;
   83 u_long  ncvhash;                        /* size of hash table - 1 */
   84 #define NCVHASH(vp)             (((uintptr_t)(vp) >> 3) & ncvhash)
   85 
   86 TAILQ_HEAD(, namecache) nclruhead;              /* LRU chain */
   87 struct  nchstats nchstats;              /* cache effectiveness statistics */
   88 
   89 POOL_INIT(namecache_pool, sizeof(struct namecache), 0, 0, 0, "ncachepl",
   90     &pool_allocator_nointr);
   91 
   92 MALLOC_DEFINE(M_CACHE, "namecache", "Dynamically allocated cache entries");
   93 
   94 int doingcache = 1;                     /* 1 => enable the cache */
   95 
   96 /* A single lock to protect cache insertion, removal and lookup */
   97 static struct simplelock namecache_slock = SIMPLELOCK_INITIALIZER;
   98 
   99 static void cache_remove(struct namecache *);
  100 static void cache_free(struct namecache *);
  101 static inline struct namecache *cache_lookup_entry(
  102     const struct vnode *, const struct componentname *);
  103 
  104 static void
  105 cache_remove(struct namecache *ncp)
  106 {
  107 
  108         LOCK_ASSERT(simple_lock_held(&namecache_slock));
  109 
  110         ncp->nc_dvp = NULL;
  111         ncp->nc_vp = NULL;
  112 
  113         TAILQ_REMOVE(&nclruhead, ncp, nc_lru);
  114         if (ncp->nc_hash.le_prev != NULL) {
  115                 LIST_REMOVE(ncp, nc_hash);
  116                 ncp->nc_hash.le_prev = NULL;
  117         }
  118         if (ncp->nc_vhash.le_prev != NULL) {
  119                 LIST_REMOVE(ncp, nc_vhash);
  120                 ncp->nc_vhash.le_prev = NULL;
  121         }
  122         if (ncp->nc_vlist.le_prev != NULL) {
  123                 LIST_REMOVE(ncp, nc_vlist);
  124                 ncp->nc_vlist.le_prev = NULL;
  125         }
  126         if (ncp->nc_dvlist.le_prev != NULL) {
  127                 LIST_REMOVE(ncp, nc_dvlist);
  128                 ncp->nc_dvlist.le_prev = NULL;
  129         }
  130 }
  131 
  132 static void
  133 cache_free(struct namecache *ncp)
  134 {
  135 
  136         pool_put(&namecache_pool, ncp);
  137         numcache--;
  138 }
  139 
  140 static inline struct namecache *
  141 cache_lookup_entry(const struct vnode *dvp, const struct componentname *cnp)
  142 {
  143         struct nchashhead *ncpp;
  144         struct namecache *ncp;
  145 
  146         LOCK_ASSERT(simple_lock_held(&namecache_slock));
  147 
  148         ncpp = &nchashtbl[NCHASH(cnp, dvp)];
  149 
  150         LIST_FOREACH(ncp, ncpp, nc_hash) {
  151                 if (ncp->nc_dvp == dvp &&
  152                     ncp->nc_nlen == cnp->cn_namelen &&
  153                     !memcmp(ncp->nc_name, cnp->cn_nameptr, (u_int)ncp->nc_nlen))
  154                         break;
  155         }
  156 
  157         return ncp;
  158 }
  159 
  160 /*
  161  * Look for a the name in the cache. We don't do this
  162  * if the segment name is long, simply so the cache can avoid
  163  * holding long names (which would either waste space, or
  164  * add greatly to the complexity).
  165  *
  166  * Lookup is called with ni_dvp pointing to the directory to search,
  167  * ni_ptr pointing to the name of the entry being sought, ni_namelen
  168  * tells the length of the name, and ni_hash contains a hash of
  169  * the name. If the lookup succeeds, the vnode is locked, stored in ni_vp
  170  * and a status of zero is returned. If the locking fails for whatever
  171  * reason, the vnode is unlocked and the error is returned to caller.
  172  * If the lookup determines that the name does not exist (negative cacheing),
  173  * a status of ENOENT is returned. If the lookup fails, a status of -1
  174  * is returned.
  175  */
  176 int
  177 cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp)
  178 {
  179         struct namecache *ncp;
  180         struct vnode *vp;
  181         int error;
  182 
  183         if (!doingcache) {
  184                 cnp->cn_flags &= ~MAKEENTRY;
  185                 *vpp = NULL;
  186                 return (-1);
  187         }
  188 
  189         if (cnp->cn_namelen > NCHNAMLEN) {
  190                 /* XXXSMP - updating stats without lock; do we care? */
  191                 nchstats.ncs_long++;
  192                 cnp->cn_flags &= ~MAKEENTRY;
  193                 goto fail;
  194         }
  195         simple_lock(&namecache_slock);
  196         ncp = cache_lookup_entry(dvp, cnp);
  197         if (ncp == NULL) {
  198                 nchstats.ncs_miss++;
  199                 goto fail_wlock;
  200         }
  201         if ((cnp->cn_flags & MAKEENTRY) == 0) {
  202                 nchstats.ncs_badhits++;
  203                 goto remove;
  204         } else if (ncp->nc_vp == NULL) {
  205                 /*
  206                  * Restore the ISWHITEOUT flag saved earlier.
  207                  */
  208                 cnp->cn_flags |= ncp->nc_flags;
  209                 if (cnp->cn_nameiop != CREATE ||
  210                     (cnp->cn_flags & ISLASTCN) == 0) {
  211                         nchstats.ncs_neghits++;
  212                         /*
  213                          * Move this slot to end of LRU chain,
  214                          * if not already there.
  215                          */
  216                         if (TAILQ_NEXT(ncp, nc_lru) != 0) {
  217                                 TAILQ_REMOVE(&nclruhead, ncp, nc_lru);
  218                                 TAILQ_INSERT_TAIL(&nclruhead, ncp, nc_lru);
  219                         }
  220                         simple_unlock(&namecache_slock);
  221                         return (ENOENT);
  222                 } else {
  223                         nchstats.ncs_badhits++;
  224                         goto remove;
  225                 }
  226         }
  227 
  228         vp = ncp->nc_vp;
  229 
  230         /*
  231          * Move this slot to end of LRU chain, if not already there.
  232          */
  233         if (TAILQ_NEXT(ncp, nc_lru) != 0) {
  234                 TAILQ_REMOVE(&nclruhead, ncp, nc_lru);
  235                 TAILQ_INSERT_TAIL(&nclruhead, ncp, nc_lru);
  236         }
  237 
  238         error = vget(vp, LK_NOWAIT);
  239 
  240         /* Release the name cache mutex while we get reference to the vnode */
  241         simple_unlock(&namecache_slock);
  242 
  243 #ifdef DEBUG
  244         /*
  245          * since we released namecache_slock,
  246          * we can't use this pointer any more.
  247          */
  248         ncp = NULL;
  249 #endif /* DEBUG */
  250 
  251         if (error) {
  252                 KASSERT(error == EBUSY);
  253                 /*
  254                  * this vnode is being cleaned out.
  255                  */
  256                 nchstats.ncs_falsehits++; /* XXX badhits? */
  257                 goto fail;
  258         }
  259 
  260         if (vp == dvp) {        /* lookup on "." */
  261                 error = 0;
  262         } else if (cnp->cn_flags & ISDOTDOT) {
  263                 VOP_UNLOCK(dvp, 0);
  264                 error = vn_lock(vp, LK_EXCLUSIVE);
  265                 vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY);
  266         } else {
  267                 error = vn_lock(vp, LK_EXCLUSIVE);
  268         }
  269 
  270         /*
  271          * Check that the lock succeeded.
  272          */
  273         if (error) {
  274                 /* XXXSMP - updating stats without lock; do we care? */
  275                 nchstats.ncs_badhits++;
  276                 *vpp = NULL;
  277                 return (-1);
  278         }
  279 
  280         /* XXXSMP - updating stats without lock; do we care? */
  281         nchstats.ncs_goodhits++;
  282         *vpp = vp;
  283         return (0);
  284 
  285 remove:
  286         /*
  287          * Last component and we are renaming or deleting,
  288          * the cache entry is invalid, or otherwise don't
  289          * want cache entry to exist.
  290          */
  291         cache_remove(ncp);
  292         cache_free(ncp);
  293 
  294 fail_wlock:
  295         simple_unlock(&namecache_slock);
  296 fail:
  297         *vpp = NULL;
  298         return (-1);
  299 }
  300 
  301 int
  302 cache_lookup_raw(struct vnode *dvp, struct vnode **vpp,
  303     struct componentname *cnp)
  304 {
  305         struct namecache *ncp;
  306         struct vnode *vp;
  307         int error;
  308 
  309         if (!doingcache) {
  310                 cnp->cn_flags &= ~MAKEENTRY;
  311                 *vpp = NULL;
  312                 return (-1);
  313         }
  314 
  315         if (cnp->cn_namelen > NCHNAMLEN) {
  316                 /* XXXSMP - updating stats without lock; do we care? */
  317                 nchstats.ncs_long++;
  318                 cnp->cn_flags &= ~MAKEENTRY;
  319                 goto fail;
  320         }
  321         simple_lock(&namecache_slock);
  322         ncp = cache_lookup_entry(dvp, cnp);
  323         if (ncp == NULL) {
  324                 nchstats.ncs_miss++;
  325                 goto fail_wlock;
  326         }
  327         /*
  328          * Move this slot to end of LRU chain,
  329          * if not already there.
  330          */
  331         if (TAILQ_NEXT(ncp, nc_lru) != 0) {
  332                 TAILQ_REMOVE(&nclruhead, ncp, nc_lru);
  333                 TAILQ_INSERT_TAIL(&nclruhead, ncp, nc_lru);
  334         }
  335 
  336         vp = ncp->nc_vp;
  337         if (vp == NULL) {
  338                 /*
  339                  * Restore the ISWHITEOUT flag saved earlier.
  340                  */
  341                 cnp->cn_flags |= ncp->nc_flags;
  342                 nchstats.ncs_neghits++;
  343                 simple_unlock(&namecache_slock);
  344                 return (ENOENT);
  345         }
  346 
  347         error = vget(vp, LK_NOWAIT);
  348 
  349         /* Release the name cache mutex while we get reference to the vnode */
  350         simple_unlock(&namecache_slock);
  351 
  352         if (error) {
  353                 KASSERT(error == EBUSY);
  354                 /*
  355                  * this vnode is being cleaned out.
  356                  */
  357                 nchstats.ncs_falsehits++; /* XXX badhits? */
  358                 goto fail;
  359         }
  360 
  361         *vpp = vp;
  362 
  363         return 0;
  364 
  365 fail_wlock:
  366         simple_unlock(&namecache_slock);
  367 fail:
  368         *vpp = NULL;
  369         return -1;
  370 }
  371 
  372 /*
  373  * Scan cache looking for name of directory entry pointing at vp.
  374  *
  375  * Fill in dvpp.
  376  *
  377  * If bufp is non-NULL, also place the name in the buffer which starts
  378  * at bufp, immediately before *bpp, and move bpp backwards to point
  379  * at the start of it.  (Yes, this is a little baroque, but it's done
  380  * this way to cater to the whims of getcwd).
  381  *
  382  * Returns 0 on success, -1 on cache miss, positive errno on failure.
  383  */
  384 int
  385 cache_revlookup(struct vnode *vp, struct vnode **dvpp, char **bpp, char *bufp)
  386 {
  387         struct namecache *ncp;
  388         struct vnode *dvp;
  389         struct ncvhashhead *nvcpp;
  390         char *bp;
  391 
  392         if (!doingcache)
  393                 goto out;
  394 
  395         nvcpp = &ncvhashtbl[NCVHASH(vp)];
  396 
  397         simple_lock(&namecache_slock);
  398         LIST_FOREACH(ncp, nvcpp, nc_vhash) {
  399                 if (ncp->nc_vp == vp &&
  400                     (dvp = ncp->nc_dvp) != NULL &&
  401                     dvp != vp) {                /* avoid pesky . entries.. */
  402 
  403 #ifdef DIAGNOSTIC
  404                         if (ncp->nc_nlen == 1 &&
  405                             ncp->nc_name[0] == '.')
  406                                 panic("cache_revlookup: found entry for .");
  407 
  408                         if (ncp->nc_nlen == 2 &&
  409                             ncp->nc_name[0] == '.' &&
  410                             ncp->nc_name[1] == '.')
  411                                 panic("cache_revlookup: found entry for ..");
  412 #endif
  413                         nchstats.ncs_revhits++;
  414 
  415                         if (bufp) {
  416                                 bp = *bpp;
  417                                 bp -= ncp->nc_nlen;
  418                                 if (bp <= bufp) {
  419                                         *dvpp = NULL;
  420                                         simple_unlock(&namecache_slock);
  421                                         return (ERANGE);
  422                                 }
  423                                 memcpy(bp, ncp->nc_name, ncp->nc_nlen);
  424                                 *bpp = bp;
  425                         }
  426 
  427                         /* XXX MP: how do we know dvp won't evaporate? */
  428                         *dvpp = dvp;
  429                         simple_unlock(&namecache_slock);
  430                         return (0);
  431                 }
  432         }
  433         nchstats.ncs_revmiss++;
  434         simple_unlock(&namecache_slock);
  435  out:
  436         *dvpp = NULL;
  437         return (-1);
  438 }
  439 
  440 /*
  441  * Add an entry to the cache
  442  */
  443 void
  444 cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp)
  445 {
  446         struct namecache *ncp;
  447         struct namecache *oncp;
  448         struct nchashhead *ncpp;
  449         struct ncvhashhead *nvcpp;
  450 
  451 #ifdef DIAGNOSTIC
  452         if (cnp->cn_namelen > NCHNAMLEN)
  453                 panic("cache_enter: name too long");
  454 #endif
  455         if (!doingcache)
  456                 return;
  457         /*
  458          * Free the cache slot at head of lru chain.
  459          */
  460         simple_lock(&namecache_slock);
  461 
  462         if (numcache < numvnodes) {
  463                 numcache++;
  464                 simple_unlock(&namecache_slock);
  465                 ncp = pool_get(&namecache_pool, PR_WAITOK);
  466                 memset(ncp, 0, sizeof(*ncp));
  467                 simple_lock(&namecache_slock);
  468         } else if ((ncp = TAILQ_FIRST(&nclruhead)) != NULL) {
  469                 cache_remove(ncp);
  470         } else {
  471                 simple_unlock(&namecache_slock);
  472                 return;
  473         }
  474 
  475         /*
  476          * Concurrent lookups in the same directory may race for a
  477          * cache entry.  if there's a duplicated entry, free it.
  478          */
  479         oncp = cache_lookup_entry(dvp, cnp);
  480         if (oncp) {
  481                 cache_remove(oncp);
  482                 cache_free(oncp);
  483         }
  484         KASSERT(cache_lookup_entry(dvp, cnp) == NULL);
  485 
  486         /* Grab the vnode we just found. */
  487         ncp->nc_vp = vp;
  488         if (vp == NULL) {
  489                 /*
  490                  * For negative hits, save the ISWHITEOUT flag so we can
  491                  * restore it later when the cache entry is used again.
  492                  */
  493                 ncp->nc_flags = cnp->cn_flags & ISWHITEOUT;
  494         }
  495         /* Fill in cache info. */
  496         ncp->nc_dvp = dvp;
  497         LIST_INSERT_HEAD(&dvp->v_dnclist, ncp, nc_dvlist);
  498         if (vp)
  499                 LIST_INSERT_HEAD(&vp->v_nclist, ncp, nc_vlist);
  500         ncp->nc_nlen = cnp->cn_namelen;
  501         memcpy(ncp->nc_name, cnp->cn_nameptr, (unsigned)ncp->nc_nlen);
  502         TAILQ_INSERT_TAIL(&nclruhead, ncp, nc_lru);
  503         ncpp = &nchashtbl[NCHASH(cnp, dvp)];
  504         LIST_INSERT_HEAD(ncpp, ncp, nc_hash);
  505 
  506         ncp->nc_vhash.le_prev = NULL;
  507         ncp->nc_vhash.le_next = NULL;
  508 
  509         /*
  510          * Create reverse-cache entries (used in getcwd) for directories.
  511          * (and in linux procfs exe node)
  512          */
  513         if (vp != NULL &&
  514             vp != dvp &&
  515 #ifndef NAMECACHE_ENTER_REVERSE
  516             vp->v_type == VDIR &&
  517 #endif
  518             (ncp->nc_nlen > 2 ||
  519             (ncp->nc_nlen > 1 && ncp->nc_name[1] != '.') ||
  520             (/* ncp->nc_nlen > 0 && */ ncp->nc_name[0] != '.'))) {
  521                 nvcpp = &ncvhashtbl[NCVHASH(vp)];
  522                 LIST_INSERT_HEAD(nvcpp, ncp, nc_vhash);
  523         }
  524         simple_unlock(&namecache_slock);
  525 }
  526 
  527 /*
  528  * Name cache initialization, from vfs_init() when we are booting
  529  */
  530 void
  531 nchinit(void)
  532 {
  533 
  534         TAILQ_INIT(&nclruhead);
  535         nchashtbl =
  536             hashinit(desiredvnodes, HASH_LIST, M_CACHE, M_WAITOK, &nchash);
  537         ncvhashtbl =
  538 #ifdef NAMECACHE_ENTER_REVERSE
  539             hashinit(desiredvnodes, HASH_LIST, M_CACHE, M_WAITOK, &ncvhash);
  540 #else
  541             hashinit(desiredvnodes/8, HASH_LIST, M_CACHE, M_WAITOK, &ncvhash);
  542 #endif
  543 }
  544 
  545 /*
  546  * Name cache reinitialization, for when the maximum number of vnodes increases.
  547  */
  548 void
  549 nchreinit(void)
  550 {
  551         struct namecache *ncp;
  552         struct nchashhead *oldhash1, *hash1;
  553         struct ncvhashhead *oldhash2, *hash2;
  554         u_long i, oldmask1, oldmask2, mask1, mask2;
  555 
  556         hash1 = hashinit(desiredvnodes, HASH_LIST, M_CACHE, M_WAITOK, &mask1);
  557         hash2 =
  558 #ifdef NAMECACHE_ENTER_REVERSE
  559             hashinit(desiredvnodes, HASH_LIST, M_CACHE, M_WAITOK, &mask2);
  560 #else
  561             hashinit(desiredvnodes/8, HASH_LIST, M_CACHE, M_WAITOK, &mask2);
  562 #endif
  563         simple_lock(&namecache_slock);
  564         oldhash1 = nchashtbl;
  565         oldmask1 = nchash;
  566         nchashtbl = hash1;
  567         nchash = mask1;
  568         oldhash2 = ncvhashtbl;
  569         oldmask2 = ncvhash;
  570         ncvhashtbl = hash2;
  571         ncvhash = mask2;
  572         for (i = 0; i <= oldmask1; i++) {
  573                 while ((ncp = LIST_FIRST(&oldhash1[i])) != NULL) {
  574                         LIST_REMOVE(ncp, nc_hash);
  575                         ncp->nc_hash.le_prev = NULL;
  576                 }
  577         }
  578         for (i = 0; i <= oldmask2; i++) {
  579                 while ((ncp = LIST_FIRST(&oldhash2[i])) != NULL) {
  580                         LIST_REMOVE(ncp, nc_vhash);
  581                         ncp->nc_vhash.le_prev = NULL;
  582                 }
  583         }
  584         simple_unlock(&namecache_slock);
  585         hashdone(oldhash1, M_CACHE);
  586         hashdone(oldhash2, M_CACHE);
  587 }
  588 
  589 /*
  590  * Cache flush, a particular vnode; called when a vnode is renamed to
  591  * hide entries that would now be invalid
  592  */
  593 void
  594 cache_purge1(struct vnode *vp, const struct componentname *cnp, int flags)
  595 {
  596         struct namecache *ncp, *ncnext;
  597 
  598         simple_lock(&namecache_slock);
  599         if (flags & PURGE_PARENTS) {
  600                 for (ncp = LIST_FIRST(&vp->v_nclist); ncp != NULL;
  601                     ncp = ncnext) {
  602                         ncnext = LIST_NEXT(ncp, nc_vlist);
  603                         cache_remove(ncp);
  604                         cache_free(ncp);
  605                 }
  606         }
  607         if (flags & PURGE_CHILDREN) {
  608                 for (ncp = LIST_FIRST(&vp->v_dnclist); ncp != NULL;
  609                     ncp = ncnext) {
  610                         ncnext = LIST_NEXT(ncp, nc_dvlist);
  611                         cache_remove(ncp);
  612                         cache_free(ncp);
  613                 }
  614         }
  615         if (cnp != NULL) {
  616                 ncp = cache_lookup_entry(vp, cnp);
  617                 if (ncp) {
  618                         cache_remove(ncp);
  619                         cache_free(ncp);
  620                 }
  621         }
  622         simple_unlock(&namecache_slock);
  623 }
  624 
  625 /*
  626  * Cache flush, a whole filesystem; called when filesys is umounted to
  627  * remove entries that would now be invalid.
  628  */
  629 void
  630 cache_purgevfs(struct mount *mp)
  631 {
  632         struct namecache *ncp, *nxtcp;
  633 
  634         simple_lock(&namecache_slock);
  635         for (ncp = TAILQ_FIRST(&nclruhead); ncp != NULL; ncp = nxtcp) {
  636                 nxtcp = TAILQ_NEXT(ncp, nc_lru);
  637                 if (ncp->nc_dvp == NULL || ncp->nc_dvp->v_mount != mp) {
  638                         continue;
  639                 }
  640                 /* Free the resources we had. */
  641                 cache_remove(ncp);
  642                 cache_free(ncp);
  643         }
  644         simple_unlock(&namecache_slock);
  645 }
  646 
  647 #ifdef DDB
  648 void
  649 namecache_print(struct vnode *vp, void (*pr)(const char *, ...))
  650 {
  651         struct vnode *dvp = NULL;
  652         struct namecache *ncp;
  653 
  654         TAILQ_FOREACH(ncp, &nclruhead, nc_lru) {
  655                 if (ncp->nc_vp == vp) {
  656                         (*pr)("name %.*s\n", ncp->nc_nlen, ncp->nc_name);
  657                         dvp = ncp->nc_dvp;
  658                 }
  659         }
  660         if (dvp == NULL) {
  661                 (*pr)("name not found\n");
  662                 return;
  663         }
  664         vp = dvp;
  665         TAILQ_FOREACH(ncp, &nclruhead, nc_lru) {
  666                 if (ncp->nc_vp == vp) {
  667                         (*pr)("parent %.*s\n", ncp->nc_nlen, ncp->nc_name);
  668                 }
  669         }
  670 }
  671 #endif
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FreeBSD/Linux Kernel Cross Reference sys/kern/vfs_cache.c

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