path_cache.c

/*
 * Copyright (c) 2021-2021 Huawei Device Co., Ltd. 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 the copyright holder 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 HOLDER 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 "path_cache.h"
#include "los_config.h"
#include "los_hash.h"
#include "stdlib.h"
#include "limits.h"
#include "vnode.h"

#define PATH_CACHE_HASH_MASK (LOSCFG_MAX_PATH_CACHE_SIZE - 1)
LIST_HEAD g_pathCacheHashEntrys[LOSCFG_MAX_PATH_CACHE_SIZE];

int PathCacheInit(void)
{
    for (int i = 0; i < LOSCFG_MAX_PATH_CACHE_SIZE; i++) {
        LOS_ListInit(&g_pathCacheHashEntrys[i]);
    }
    return LOS_OK;
}

void PathCacheDump(void)
{
    PRINTK("-------->pathCache dump in\n");
    for (int i = 0; i < LOSCFG_MAX_PATH_CACHE_SIZE; i++) {
        struct PathCache *nc = NULL;
        LIST_HEAD *nhead = &g_pathCacheHashEntrys[i];

        LOS_DL_LIST_FOR_EACH_ENTRY(nc, nhead, struct PathCache, hashEntry) {
            PRINTK("    pathCache dump hash %d item %s %p %p %d\n", i,
                nc->name, nc->parentVnode, nc->childVnode, nc->nameLen);
        }
    }
    PRINTK("-------->pathCache dump out\n");
}

void PathCacheMemoryDump(void)
{
    int pathCacheNum = 0;
    int nameSum = 0;
    for (int i = 0; i < LOSCFG_MAX_PATH_CACHE_SIZE; i++) {
        LIST_HEAD *dhead = &g_pathCacheHashEntrys[i];
        struct PathCache *dent = NULL;

        LOS_DL_LIST_FOR_EACH_ENTRY(dent, dhead, struct PathCache, hashEntry) {
            pathCacheNum++;
            nameSum += dent->nameLen;
        }
    }
    PRINTK("pathCache number = %d\n", pathCacheNum);
    PRINTK("pathCache memory size = %d(B)\n", pathCacheNum * sizeof(struct PathCache) + nameSum);
}

static uint32_t NameHash(const char *name, int len, struct Vnode *dvp)
{
    uint32_t hash;
    hash = LOS_HashFNV32aBuf(name, len, FNV1_32A_INIT);
    hash = LOS_HashFNV32aBuf(&dvp, sizeof(struct Vnode *), hash);
    return hash;
}

static void PathCacheInsert(struct Vnode *parent, struct PathCache *cache, const char* name, int len)
{
    int hash = NameHash(name, len, parent) & PATH_CACHE_HASH_MASK;
    LOS_ListAdd(&g_pathCacheHashEntrys[hash], &cache->hashEntry);
}

struct PathCache *PathCacheAlloc(struct Vnode *parent, struct Vnode *vnode, const char *name, uint8_t len)
{
    struct PathCache *nc = NULL;
    size_t pathCacheSize;
    int ret;

    if (name == NULL || len > NAME_MAX || parent == NULL || vnode == NULL) {
        return NULL;
    }
    pathCacheSize = sizeof(struct PathCache) + len + 1;

    nc = (struct PathCache*)zalloc(pathCacheSize);
    if (nc == NULL) {
        PRINT_ERR("pathCache alloc failed, no memory!\n");
        return NULL;
    }

    ret = strncpy_s(nc->name, len + 1, name, len);
    if (ret != LOS_OK) {
        return NULL;
    }

    nc->parentVnode = parent;
    nc->nameLen = len;
    nc->childVnode = vnode;

    LOS_ListAdd((&(parent->childPathCaches)), (&(nc->childEntry)));
    LOS_ListAdd((&(vnode->parentPathCaches)), (&(nc->parentEntry)));

    PathCacheInsert(parent, nc, name, len);

    return nc;
}

int PathCacheFree(struct PathCache *nc)
{
    if (nc == NULL) {
        PRINT_ERR("pathCache free: invalid pathCache\n");
        return -ENOENT;
    }

    LOS_ListDelete(&nc->hashEntry);
    LOS_ListDelete(&nc->parentEntry);
    LOS_ListDelete(&nc->childEntry);
    free(nc);

    return LOS_OK;
}

int PathCacheLookup(struct Vnode *parent, const char *name, int len, struct Vnode **vnode)
{
    struct PathCache *nc = NULL;
    int hash = NameHash(name, len, parent) & PATH_CACHE_HASH_MASK;
    LIST_HEAD *dhead = &g_pathCacheHashEntrys[hash];

    LOS_DL_LIST_FOR_EACH_ENTRY(nc, dhead, struct PathCache, hashEntry) {
        if (nc->parentVnode == parent && nc->nameLen == len && !strncmp(nc->name, name, len)) {
            *vnode = nc->childVnode;
            return LOS_OK;
        }
    }
    return -ENOENT;
}

static void FreeChildPathCache(struct Vnode *vnode)
{
    struct PathCache *item = NULL;
    struct PathCache *nextItem = NULL;

    LOS_DL_LIST_FOR_EACH_ENTRY_SAFE(item, nextItem, &(vnode->childPathCaches), struct PathCache, childEntry) {
        PathCacheFree(item);
    }
}

static void FreeParentPathCache(struct Vnode *vnode)
{
    struct PathCache *item = NULL;
    struct PathCache *nextItem = NULL;

    LOS_DL_LIST_FOR_EACH_ENTRY_SAFE(item, nextItem, &(vnode->parentPathCaches), struct PathCache, parentEntry) {
        PathCacheFree(item);
    }
}

void VnodePathCacheFree(struct Vnode *vnode)
{
    if (vnode == NULL) {
        return;
    }
    FreeParentPathCache(vnode);
    FreeChildPathCache(vnode);
}