NetBSD/sys/kern/vfs_dirhash.c

503 lines
13 KiB
C

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