OpenHarmony设备开发 小型系统内核(LiteOS-A) 扩展组件 文件系统

struct MountOps g_yourFsMountOps = {
    .Mount = YourMountMethod,
};

struct file_operations_vfs g_yourFsFileOps = {
  .read = YourReadMethod,
  .write = YourWriteMethod,
}

struct VnodeOps g_yourFsVnodeOps = {
    .Create = YourCreateMethod;
    .Lookup = YourLookupMethod;
    .Reclaim = YourReclaimMethod;
};

FSMAP_ENTRY(yourfs_fsmap, "your fs name", g_yourFsMountOps, TRUE, TRUE);  // 注册文件系统

int (*Mount)(struct Mount *mount, struct Vnode *blkDriver, const void *data);

struct Mount {
    const struct MountOps *ops;        /* Mount相关的函数钩子 */
    struct Vnode *vnodeCovered;        /* Mount之后的文件系统root节点 */
    void *data;                        /* Mount点的私有数据 */
};

int VfsJffs2Bind(struct Mount *mnt, struct Vnode *blkDriver, const void *data)
{
    int ret;
    int partNo;
    mtd_partition *p = NULL;
    struct MtdDev *mtd = NULL;
    struct Vnode *pv = NULL;
    struct jffs2_inode *rootNode = NULL;

    LOS_MuxLock(&g_jffs2FsLock, (uint32_t)JFFS2_WAITING_FOREVER);

    /* 首先是从驱动节点中获取文件系统需要的信息，例如jffs2读取的是分区的编号 */
    p = (mtd_partition *)((struct drv_data *)blkDriver->data)->priv;
    mtd = (struct MtdDev *)(p->mtd_info);

    if (mtd == NULL || mtd->type != MTD_NORFLASH) {
        LOS_MuxUnlock(&g_jffs2FsLock);
        return -EINVAL;
    }

    partNo = p->patitionnum;

    /* 然后生成一个文件系统的根Vnode，这里注意不要搞混rootNode和根Vnode，rootNode类型是inode，是jffs2内部维护的私有数据，而Vnode是VFS的概念，是通用的文件节点，
       这一步实际上就是把文件系统内部的私有信息保存到Vnode中，这样就可以通过Vnode直接找到文件系统中的对应文件。
     */
    ret = jffs2_mount(partNo, &rootNode);
    if (ret != 0) {
        LOS_MuxUnlock(&g_jffs2FsLock);
        return ret;
    }

    ret = VnodeAlloc(&g_jffs2Vops, &pv);
    if (ret != 0) {
        LOS_MuxUnlock(&g_jffs2FsLock);
        goto ERROR_WITH_VNODE;
    }

    /* 下面这段填写的是关于这个Vnode对应文件的相关信息，uid\gid\mode这部分信息，有的文件系统可能不支持，可以不填 */
    pv->type = VNODE_TYPE_DIR;
    pv->data = (void *)rootNode;
    pv->originMount = mnt;
    pv->fop = &g_jffs2Fops;
    mnt->data = p;
    mnt->vnodeCovered = pv;
    pv->uid = rootNode->i_uid;
    pv->gid = rootNode->i_gid;
    pv->mode = rootNode->i_mode;

    /* 这里的HashInsert是为了防止重复生成已经生成过的Vnode， 第二个参数一般会选择本文件系统内可以唯一确定某一个文件的信息，例如这里是jffs2内部inode的地址 */
    (void)VfsHashInsert(pv, rootNode->i_ino);

    g_jffs2PartList[partNo] = blkDriver;

    LOS_MuxUnlock(&g_jffs2FsLock);

    return 0;
ERROR_WITH_VNODE:
    return ret;
}
...
...
const struct MountOps jffs_operations = {
    .Mount = VfsJffs2Bind,
    ...
    ...
};

int (*Lookup)(struct Vnode *parent, const char *name, int len, struct Vnode **vnode);

int VfsJffs2Lookup(struct Vnode *parentVnode, const char *path, int len, struct Vnode **ppVnode)
{
    int ret;
    struct Vnode *newVnode = NULL;
    struct jffs2_inode *node = NULL;
    struct jffs2_inode *parentNode = NULL;

    LOS_MuxLock(&g_jffs2FsLock, (uint32_t)JFFS2_WAITING_FOREVER);

    /* 首先从private data中提取父节点的信息 */
    parentNode = (struct jffs2_inode *)parentVnode->data;

    /* 然后查询得到目标节点的信息，注意这里调用的jffs2_lookup是jffs2本身的查询函数 */
    node = jffs2_lookup(parentNode, (const unsigned char *)path, len);
    if (!node) {
        LOS_MuxUnlock(&g_jffs2FsLock);
        return -ENOENT;
    }

    /* 接着先校验一下查找到的目标是否已经有现成的vnode了，这里对应之前提到的VfsHashInsert */
    (void)VfsHashGet(parentVnode->originMount, node->i_ino, &newVnode, NULL, NULL);
    LOS_MuxUnlock(&g_jffs2FsLock);
    if (newVnode) {
        newVnode->parent = parentVnode;
        *ppVnode = newVnode;
        return 0;
    }

    /* 如果vnode不存在，就新生成一个vnode，并填写相关信息 */
    ret = VnodeAlloc(&g_jffs2Vops, &newVnode);
    if (ret != 0) {
        PRINT_ERR("%s-%d, ret: %x\n", __FUNCTION__, __LINE__, ret);
        (void)jffs2_iput(node);
        LOS_MuxUnlock(&g_jffs2FsLock);
        return ret;
    }

    Jffs2SetVtype(node, newVnode);
    newVnode->fop = parentVnode->fop;
    newVnode->data = node;
    newVnode->parent = parentVnode;
    newVnode->originMount = parentVnode->originMount;
    newVnode->uid = node->i_uid;
    newVnode->gid = node->i_gid;
    newVnode->mode = node->i_mode;
    
    /* 同时不要忘记将新生成的vnode插入hashtable中 */
    (void)VfsHashInsert(newVnode, node->i_ino);

    *ppVnode = newVnode;

    LOS_MuxUnlock(&g_jffs2FsLock);
    return 0;
}

├─proc
│  ├─plimits
│  │  ├─plimits.plimiter_add
│  │  ├─plimits.plimiter_delete
│  │  ├─plimits.procs
│  │  ├─plimits.limiters
│  │  ├─pids.max
│  │  ├─sched.period
│  │  ├─sched.quota
│  │  ├─sched.stat
│  │  ├─memory.failcnt
│  │  ├─memory.limit
│  │  ├─memory.peak
│  │  ├─memory.usage
│  │  ├─memory.oom_ctrl
│  │  └─memory.stat

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#define LOS_OK 0
#define LOS_NOK -1

int main ()
{
    int ret;
    ssize_t len;
    int fd = -1;
    //get main pid
    int mainpid = getpid();
    char plimitsA[128] = "/proc/plimits/plimitsA";
    char plimitsAPids[128] = "/proc/plimits/plimitsA/pids.max";
    char plimitsAMemoryLimit[128] = "/proc/plimits/plimitsA/memory.limit";
    char plimitsAMemoryUsage[128] = "/proc/plimits/plimitsA/memory.usage";
    char plimitsAProcs[128] = "/proc/plimits/plimitsA/plimits.procs";
    char plimitsAAdd[128] = "/proc/plimits/plimitsA/plimits.limiter_add";
    char plimitsADelete[128] = "/proc/plimits/plimitsA/plimits.limiter_delete";
    char plimitsMem[128] = "/proc/plimits/memory.usage";
    char plimitsPid[128] = "/proc/plimits/plimits.procs";
    char *mem = NULL;
    char writeBuf[128];
    char readBuf[128];

    /* 查看根plimits组内进程 */
    memset(readBuf, 0, sizeof(readBuf));
    fd = open(plimitsPid, O_RDONLY);
    len = read(fd, readBuf, sizeof(readBuf));
    if (len != strlen(readBuf)) {
        printf("read file failed.\n");
        return LOS_NOK;
    }
    close(fd);
    printf("/proc/plimits组内进程：%s\n", readBuf);

    /* 查看根plimits组内内存使用 */
    memset(readBuf, 0, sizeof(readBuf));
    fd = open(plimitsMem, O_RDONLY);
    len = read(fd, readBuf, sizeof(readBuf));
    if (len != strlen(readBuf)) {
        printf("read file failed.\n");
        return LOS_NOK;
    }
    close(fd);
    printf("/proc/plimits组内已使用内存：%s\n", readBuf);


    /* 创建plimitsA “/proc/plimits/plimitsA” */
    ret = mkdir(plimitsA, 0777);
    if (ret != LOS_OK) {
        printf("mkdir failed.\n");
        return LOS_NOK;
    }

    /* 设置plimitsA组允许挂载进程个数 */
    memset(writeBuf, 0, sizeof(writeBuf));
    sprintf(writeBuf, "%d", 3);
    fd = open(plimitsAPids, O_WRONLY);
    len = write(fd, writeBuf, strlen(writeBuf));
    if (len != strlen(writeBuf)) {
        printf("write file failed.\n");
        return LOS_NOK;
    }
    close(fd);

    /* 挂载进程至plimitsA组 */
    memset(writeBuf, 0, sizeof(writeBuf));
    sprintf(writeBuf, "%d", mainpid);
    fd = open(plimitsAProcs, O_WRONLY);
    len = write(fd, writeBuf, strlen(writeBuf));
    if (len != strlen(writeBuf)) {
        printf("write file failed.\n");
        return LOS_NOK;
    }
    close(fd);

    /* 设置plimitsA组内分配内存限额 */
    memset(writeBuf, 0, sizeof(writeBuf));
    //limit memory
    sprintf(writeBuf, "%d", (1024*1024*3));
    fd = open(plimitsAMemoryLimit, O_WRONLY);
    len = write(fd, writeBuf, strlen(writeBuf));
    if (len != strlen(writeBuf)) {
        printf("write file failed.\n");
        return LOS_NOK;
    }
    close(fd);

    /* 查看plimitsA组内允许使用的最大内存 */
    memset(readBuf, 0, sizeof(readBuf));
    fd = open(plimitsAMemoryLimit, O_RDONLY);
    len = read(fd, readBuf, sizeof(readBuf));
    if (len != strlen(readBuf)) {
        printf("read file failed.\n");
        return LOS_NOK;
    }
    close(fd);
    printf("/proc/plimits/plimitsA组允许使用的最大内存：%s\n", readBuf);

    /* 查看plimitsA组内挂载的进程 */
    memset(readBuf, 0, sizeof(readBuf));
    fd = open(plimitsAProcs, O_RDONLY);
    len = read(fd, readBuf, sizeof(readBuf));
    if (len != strlen(readBuf)) {
        printf("read file failed.\n");
        return LOS_NOK;
    }
    close(fd);
    printf("/proc/plimits/plimitsA组内挂载的进程：%s\n", readBuf);

    /* 查看plimitsA组内存的使用情况 */
    mem = (char*)malloc(1024*1024);
    memset(mem, 0, 1024);
    memset(readBuf, 0, sizeof(readBuf));
    fd = open(plimitsAMemoryUsage, O_RDONLY);
    len = read(fd, readBuf, sizeof(readBuf));
    if (len != strlen(readBuf)) {
        printf("read file failed.\n");
        return LOS_NOK;
    }
    close(fd);
    printf("/proc/plimits/plimitsA组已使用内存：%s\n", readBuf);

    /* 删除plimitsA组内memory限制器 */
    memset(writeBuf, 0, sizeof(writeBuf));
    sprintf(writeBuf, "%s", "memory");
    fd = open(plimitsADelete, O_WRONLY);
    len = write(fd, writeBuf, strlen(writeBuf));
    if (len != strlen(writeBuf)) {
        printf("write file failed.\n");
        return LOS_NOK;
    }
    close(fd);

    /* 增加plimitsA组内memory限制器 */
    memset(writeBuf, 0, sizeof(writeBuf));
    sprintf(writeBuf, "%s", "memory");
    fd = open(plimitsAAdd, O_WRONLY);
    len = write(fd, writeBuf, strlen(writeBuf));
    if (len != strlen(writeBuf)) {
        printf("write file failed.\n");
        return LOS_NOK;
    }
    close(fd);

    /* 删除plimitsA组,首先删除memory、pids、sched限制器 */
    memset(writeBuf, 0, sizeof(writeBuf));
    sprintf(writeBuf, "%s", "memory");
    fd = open(plimitsADelete, O_WRONLY);
    len = write(fd, writeBuf, strlen(writeBuf));
    if (len != strlen(writeBuf)) {
        printf("write file failed.\n");
        return LOS_NOK;
    }
    memset(writeBuf, 0, sizeof(writeBuf));
    sprintf(writeBuf, "%s", "pids");
    fd = open(plimitsADelete, O_WRONLY);
    len = write(fd, writeBuf, strlen(writeBuf));

    memset(writeBuf, 0, sizeof(writeBuf));
    sprintf(writeBuf, "%s", "sched");
    fd = open(plimitsADelete, O_WRONLY);
    len = write(fd, writeBuf, strlen(writeBuf));
    close(fd);
    ret = rmdir(plimitsA);
    if (ret != LOS_OK) {
        printf("rmdir failed.\n");
        return LOS_NOK;
    }

    return 0;
}

/proc/plimits组内进程：
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

/proc/plimits组内已使用内存：28016640

/proc/plimits/plimitsA组允许使用的最大内存：3145728

/proc/plimits/plimitsA组内挂载的进程：
15

/proc/plimits/plimitsA组已使用内存：4096