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/*
* Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
* 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.
* 3. Neither the name of Hyra nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR CONTRIBUTORS 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/types.h>
#include <sys/queue.h>
#include <sys/mount.h>
#include <sys/vfs.h>
#include <sys/errno.h>
#include <vm/dynalloc.h>
#include <assert.h>
/* For caching */
#define MOUNTLIST_SIZE 8
/* Mountlist cache entry */
struct mountlist_entry {
TAILQ_HEAD(, mount) buckets;
};
static struct mountlist_entry *mountlist = NULL;
/*
* Cache a mountpoint
*
* @mp: Mountpoint to cache
* @path: Path this mountpoint belongs to
*
* If this cache entry already exists, -EEXIST
* will be returned.
*/
int
vfs_cache_mp(struct mount *mp, const char *path)
{
size_t hash = vfs_hash_path(path);
struct mountlist_entry *entry;
if (hash == 0) {
/* Something is wrong with the path */
return -EINVAL;
}
if (vfs_cache_fetch_mp(path, NULL) == 0) {
/* Cache hit, do not duplicate this entry */
return -EEXIST;
}
mp->phash = hash;
entry = &mountlist[hash % MOUNTLIST_SIZE];
TAILQ_INSERT_TAIL(&entry->buckets, mp, link);
return 0;
}
/*
* Fetch mountpoint from cache
*
* @path: Path of target mountpoint
* @mp: Pointer of variable where mountpoint fetched will
* be stored
*
* Returns 0 upon a cache hit, on a cache miss this
* function returns -ENOENT.
*/
int
vfs_cache_fetch_mp(const char *path, struct mount **mp)
{
size_t hash = vfs_hash_path(path);
struct mountlist_entry *entry;
struct mount *mount_iter;
if (hash == 0) {
/* Something is wrong with the path */
return -EINVAL;
}
entry = &mountlist[hash % MOUNTLIST_SIZE];
TAILQ_FOREACH(mount_iter, &entry->buckets, link) {
if (mount_iter->phash == hash) {
/* Cache hit */
if (mp != NULL) *mp = mount_iter;
return 0;
}
}
/* Cache miss */
return -ENOENT;
}
/*
* Init all caches
*/
void
vfs_init_cache(void)
{
mountlist = dynalloc(sizeof(struct mountlist_entry) * MOUNTLIST_SIZE);
__assert(mountlist != NULL);
for (size_t i = 0; i < MOUNTLIST_SIZE; ++i) {
TAILQ_INIT(&mountlist[i].buckets);
}
}
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