503 lines
13 KiB
C
503 lines
13 KiB
C
/* $NetBSD: vfs_dirhash.c,v 1.14 2021/08/21 09:59:46 andvar Exp $ */
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/*
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* Copyright (c) 2008 Reinoud Zandijk
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: vfs_dirhash.c,v 1.14 2021/08/21 09:59:46 andvar Exp $");
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/* CLEAN UP! */
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/buf.h>
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#include <sys/dirent.h>
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#include <sys/hash.h>
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#include <sys/mutex.h>
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#include <sys/pool.h>
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#include <sys/queue.h>
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#include <sys/vnode.h>
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#include <sys/sysctl.h>
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#include <sys/dirhash.h>
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#if 1
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# define DPRINTF(a) ;
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#else
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# define DPRINTF(a) printf a;
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#endif
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/*
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* The locking protocol of the dirhash structures is fairly simple:
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*
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* The global dirhash_queue is protected by the dirhashmutex. This lock is
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* internal only and is FS/mountpoint/vnode independent. On exit of the
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* exported functions this mutex is not held.
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*
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* The dirhash structure is considered part of the vnode/inode/udf_node
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* structure and will thus use the lock that protects that vnode/inode.
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*
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* The dirhash entries are considered part of the dirhash structure and thus
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* are on the same lock.
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*/
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static struct sysctllog *sysctl_log;
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static struct pool dirhash_pool;
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static struct pool dirhash_entry_pool;
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static kmutex_t dirhashmutex;
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static uint32_t maxdirhashsize = DIRHASH_SIZE;
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static uint32_t dirhashsize = 0;
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static TAILQ_HEAD(_dirhash, dirhash) dirhash_queue;
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void
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dirhash_init(void)
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{
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const struct sysctlnode *rnode, *cnode;
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size_t sz;
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uint32_t max_entries;
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/* initialise dirhash queue */
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TAILQ_INIT(&dirhash_queue);
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/* init dirhash pools */
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sz = sizeof(struct dirhash);
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pool_init(&dirhash_pool, sz, 0, 0, 0,
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"dirhpl", NULL, IPL_NONE);
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sz = sizeof(struct dirhash_entry);
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pool_init(&dirhash_entry_pool, sz, 0, 0, 0,
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"dirhepl", NULL, IPL_NONE);
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mutex_init(&dirhashmutex, MUTEX_DEFAULT, IPL_NONE);
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max_entries = maxdirhashsize / sz;
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pool_sethiwat(&dirhash_entry_pool, max_entries);
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dirhashsize = 0;
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/* create sysctl knobs and dials */
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sysctl_log = NULL;
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sysctl_createv(&sysctl_log, 0, NULL, &rnode,
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CTLFLAG_PERMANENT,
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CTLTYPE_NODE, "dirhash", NULL,
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NULL, 0, NULL, 0,
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CTL_VFS, VFS_GENERIC, CTL_CREATE, CTL_EOL);
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sysctl_createv(&sysctl_log, 0, &rnode, &cnode,
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CTLFLAG_PERMANENT,
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CTLTYPE_INT, "memused",
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SYSCTL_DESCR("current dirhash memory usage"),
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NULL, 0, &dirhashsize, 0,
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CTL_CREATE, CTL_EOL);
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sysctl_createv(&sysctl_log, 0, &rnode, &cnode,
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CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
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CTLTYPE_INT, "maxmem",
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SYSCTL_DESCR("maximum dirhash memory usage"),
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NULL, 0, &maxdirhashsize, 0,
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CTL_CREATE, CTL_EOL);
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}
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#if 0
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void
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dirhash_finish(void)
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{
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pool_destroy(&dirhash_pool);
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pool_destroy(&dirhash_entry_pool);
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mutex_destroy(&dirhashmutex);
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/* sysctl_teardown(&sysctl_log); */
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}
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#endif
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/*
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* generic dirhash implementation
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*/
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void
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dirhash_purge_entries(struct dirhash *dirh)
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{
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struct dirhash_entry *dirh_e;
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uint32_t hashline;
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if (dirh == NULL)
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return;
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if (dirh->size == 0)
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return;
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for (hashline = 0; hashline < DIRHASH_HASHSIZE; hashline++) {
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while ((dirh_e =
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LIST_FIRST(&dirh->entries[hashline])) != NULL) {
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LIST_REMOVE(dirh_e, next);
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pool_put(&dirhash_entry_pool, dirh_e);
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}
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}
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while ((dirh_e = LIST_FIRST(&dirh->free_entries)) != NULL) {
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LIST_REMOVE(dirh_e, next);
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pool_put(&dirhash_entry_pool, dirh_e);
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}
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dirh->flags &= ~DIRH_COMPLETE;
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dirh->flags |= DIRH_PURGED;
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dirh->num_files = 0;
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dirhashsize -= dirh->size;
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dirh->size = 0;
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}
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void
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dirhash_purge(struct dirhash **dirhp)
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{
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struct dirhash *dirh = *dirhp;
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if (dirh == NULL)
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return;
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/* purge its entries */
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dirhash_purge_entries(dirh);
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/* recycle */
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mutex_enter(&dirhashmutex);
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TAILQ_REMOVE(&dirhash_queue, dirh, next);
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mutex_exit(&dirhashmutex);
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pool_put(&dirhash_pool, dirh);
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*dirhp = NULL;
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}
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void
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dirhash_get(struct dirhash **dirhp)
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{
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struct dirhash *dirh;
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uint32_t hashline;
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/* if no dirhash was given, allocate one */
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dirh = *dirhp;
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if (dirh == NULL) {
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dirh = pool_get(&dirhash_pool, PR_WAITOK | PR_ZERO);
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for (hashline = 0; hashline < DIRHASH_HASHSIZE; hashline++) {
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LIST_INIT(&dirh->entries[hashline]);
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}
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}
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/* implement LRU on the dirhash queue */
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mutex_enter(&dirhashmutex);
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if (*dirhp) {
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/* remove from queue to be requeued */
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TAILQ_REMOVE(&dirhash_queue, dirh, next);
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}
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dirh->refcnt++;
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TAILQ_INSERT_HEAD(&dirhash_queue, dirh, next);
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mutex_exit(&dirhashmutex);
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*dirhp = dirh;
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}
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void
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dirhash_put(struct dirhash *dirh)
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{
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mutex_enter(&dirhashmutex);
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dirh->refcnt--;
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mutex_exit(&dirhashmutex);
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}
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void
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dirhash_enter(struct dirhash *dirh,
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struct dirent *dirent, uint64_t offset, uint32_t entry_size, int new_p)
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{
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struct dirhash *del_dirh, *prev_dirh;
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struct dirhash_entry *dirh_e;
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uint32_t hashvalue, hashline;
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int entrysize;
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/* make sure we have a dirhash to work on */
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KASSERT(dirh);
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KASSERT(dirh->refcnt > 0);
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/* are we trying to re-enter an entry? */
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if (!new_p && (dirh->flags & DIRH_COMPLETE))
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return;
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/* calculate our hash */
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hashvalue = hash32_strn(dirent->d_name, dirent->d_namlen, HASH32_STR_INIT);
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hashline = hashvalue & DIRHASH_HASHMASK;
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/* lookup and insert entry if not there yet */
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LIST_FOREACH(dirh_e, &dirh->entries[hashline], next) {
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/* check for hash collision */
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if (dirh_e->hashvalue != hashvalue)
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continue;
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if (dirh_e->offset != offset)
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continue;
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/* got it already */
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KASSERT(dirh_e->d_namlen == dirent->d_namlen);
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KASSERT(dirh_e->entry_size == entry_size);
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return;
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}
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DPRINTF(("dirhash enter %"PRIu64", %d, %d for `%*.*s`\n",
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offset, entry_size, dirent->d_namlen,
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dirent->d_namlen, dirent->d_namlen, dirent->d_name));
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/* check if entry is in free space list */
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LIST_FOREACH(dirh_e, &dirh->free_entries, next) {
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if (dirh_e->offset == offset) {
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DPRINTF(("\tremoving free entry\n"));
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LIST_REMOVE(dirh_e, next);
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pool_put(&dirhash_entry_pool, dirh_e);
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break;
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}
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}
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/* ensure we are not passing the dirhash limit */
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entrysize = sizeof(struct dirhash_entry);
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if (dirhashsize + entrysize > maxdirhashsize) {
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/* we walk the dirhash_queue, so need to lock it */
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mutex_enter(&dirhashmutex);
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del_dirh = TAILQ_LAST(&dirhash_queue, _dirhash);
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KASSERT(del_dirh);
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while (dirhashsize + entrysize > maxdirhashsize) {
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/* no use trying to delete myself */
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if (del_dirh == dirh)
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break;
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prev_dirh = TAILQ_PREV(del_dirh, _dirhash, next);
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if (del_dirh->refcnt == 0)
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dirhash_purge_entries(del_dirh);
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del_dirh = prev_dirh;
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}
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mutex_exit(&dirhashmutex);
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}
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/* add to the hashline */
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dirh_e = pool_get(&dirhash_entry_pool, PR_WAITOK | PR_ZERO);
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dirh_e->hashvalue = hashvalue;
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dirh_e->offset = offset;
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dirh_e->d_namlen = dirent->d_namlen;
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dirh_e->entry_size = entry_size;
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dirh->size += sizeof(struct dirhash_entry);
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dirh->num_files++;
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dirhashsize += sizeof(struct dirhash_entry);
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LIST_INSERT_HEAD(&dirh->entries[hashline], dirh_e, next);
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}
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void
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dirhash_enter_freed(struct dirhash *dirh, uint64_t offset,
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uint32_t entry_size)
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{
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struct dirhash_entry *dirh_e;
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/* make sure we have a dirhash to work on */
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KASSERT(dirh);
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KASSERT(dirh->refcnt > 0);
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/* check for double entry of free space */
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LIST_FOREACH(dirh_e, &dirh->free_entries, next) {
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KASSERT(dirh_e->offset != offset);
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}
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DPRINTF(("dirhash enter FREED %"PRIu64", %d\n",
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offset, entry_size));
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dirh_e = pool_get(&dirhash_entry_pool, PR_WAITOK | PR_ZERO);
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dirh_e->hashvalue = 0; /* not relevant */
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dirh_e->offset = offset;
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dirh_e->d_namlen = 0; /* not relevant */
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dirh_e->entry_size = entry_size;
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/* XXX it might be preferable to append them at the tail */
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LIST_INSERT_HEAD(&dirh->free_entries, dirh_e, next);
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dirh->size += sizeof(struct dirhash_entry);
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dirhashsize += sizeof(struct dirhash_entry);
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}
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void
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dirhash_remove(struct dirhash *dirh, struct dirent *dirent,
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uint64_t offset, uint32_t entry_size)
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{
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struct dirhash_entry *dirh_e;
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uint32_t hashvalue, hashline;
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DPRINTF(("dirhash remove %"PRIu64", %d for `%*.*s`\n",
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offset, entry_size,
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dirent->d_namlen, dirent->d_namlen, dirent->d_name));
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/* make sure we have a dirhash to work on */
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KASSERT(dirh);
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KASSERT(dirh->refcnt > 0);
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/* calculate our hash */
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hashvalue = hash32_strn(dirent->d_name, dirent->d_namlen, HASH32_STR_INIT);
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hashline = hashvalue & DIRHASH_HASHMASK;
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/* lookup entry */
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LIST_FOREACH(dirh_e, &dirh->entries[hashline], next) {
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/* check for hash collision */
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if (dirh_e->hashvalue != hashvalue)
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continue;
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if (dirh_e->offset != offset)
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continue;
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/* got it! */
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KASSERT(dirh_e->d_namlen == dirent->d_namlen);
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KASSERT(dirh_e->entry_size == entry_size);
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LIST_REMOVE(dirh_e, next);
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dirh->size -= sizeof(struct dirhash_entry);
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KASSERT(dirh->num_files > 0);
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dirh->num_files--;
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dirhashsize -= sizeof(struct dirhash_entry);
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dirhash_enter_freed(dirh, offset, entry_size);
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return;
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}
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/* not found! */
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panic("dirhash_remove couldn't find entry in hash table\n");
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}
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/*
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* BUGALERT: don't use result longer than needed, never past the node lock.
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* Call with NULL *result initially and it will return nonzero if again.
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*/
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int
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dirhash_lookup(struct dirhash *dirh, const char *d_name, int d_namlen,
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struct dirhash_entry **result)
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{
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struct dirhash_entry *dirh_e;
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uint32_t hashvalue, hashline;
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/* make sure we have a dirhash to work on */
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KASSERT(dirh);
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KASSERT(dirh->refcnt > 0);
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/* start where we were */
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if (*result) {
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dirh_e = *result;
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/* retrieve information to avoid recalculation and advance */
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hashvalue = dirh_e->hashvalue;
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dirh_e = LIST_NEXT(*result, next);
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} else {
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/* calculate our hash and lookup all entries in hashline */
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hashvalue = hash32_strn(d_name, d_namlen, HASH32_STR_INIT);
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hashline = hashvalue & DIRHASH_HASHMASK;
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dirh_e = LIST_FIRST(&dirh->entries[hashline]);
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}
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for (; dirh_e; dirh_e = LIST_NEXT(dirh_e, next)) {
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/* check for hash collision */
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if (dirh_e->hashvalue != hashvalue)
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continue;
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if (dirh_e->d_namlen != d_namlen)
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continue;
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/* might have an entry in the cache */
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*result = dirh_e;
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return 1;
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}
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*result = NULL;
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return 0;
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}
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/*
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* BUGALERT: don't use result longer than needed, never past the node lock.
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* Call with NULL *result initially and it will return nonzero if again.
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*/
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int
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dirhash_lookup_freed(struct dirhash *dirh, uint32_t min_entrysize,
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struct dirhash_entry **result)
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{
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struct dirhash_entry *dirh_e;
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/* make sure we have a dirhash to work on */
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KASSERT(dirh);
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KASSERT(dirh->refcnt > 0);
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/* start where we were */
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if (*result) {
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dirh_e = LIST_NEXT(*result, next);
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} else {
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/* lookup all entries that match */
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dirh_e = LIST_FIRST(&dirh->free_entries);
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}
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for (; dirh_e; dirh_e = LIST_NEXT(dirh_e, next)) {
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/* check for minimum size */
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if (dirh_e->entry_size < min_entrysize)
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continue;
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/* might be a candidate */
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*result = dirh_e;
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return 1;
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}
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*result = NULL;
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return 0;
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}
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bool
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dirhash_dir_isempty(struct dirhash *dirh)
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{
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#ifdef DEBUG
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struct dirhash_entry *dirh_e;
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int hashline, num;
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num = 0;
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for (hashline = 0; hashline < DIRHASH_HASHSIZE; hashline++) {
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LIST_FOREACH(dirh_e, &dirh->entries[hashline], next) {
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num++;
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}
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}
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if (dirh->num_files != num) {
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printf("dirhash_dir_isempy: dirhash_counter failed: "
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"dirh->num_files = %d, counted %d\n",
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dirh->num_files, num);
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assert(dirh->num_files == num);
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}
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#endif
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/* assert the directory hash info is valid */
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KASSERT(dirh->flags & DIRH_COMPLETE);
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/* the directory is empty when only '..' lifes in it or is absent */
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return (dirh->num_files <= 1);
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}
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