LiteOS-A內(nèi)核中的procfs文件系統(tǒng)分析

struct Vnode {
    enum VnodeType type;                /* Vnode節(jié)點類型 */
    int useCount;                       /* 節(jié)點鏈接數(shù) */
    uint32_t hash;                      /* 哈希值 */
    uint uid;                           /* 文件擁有者的user id */
    uint gid;                           /* 文件群組id */
    mode_t mode;                        /* 文件讀寫執(zhí)行權(quán)限 */
    LIST_HEAD parentPathCaches;         /* 指向父節(jié)點的路徑緩存 */
    LIST_HEAD childPathCaches;          /* 指向兒子節(jié)點的路徑緩存 */
    struct Vnode *parent;               /* vnode父節(jié)點 */
    struct VnodeOps *vop;               /* vnode操作接口 */
    struct file_operations_vfs *fop;    /* 文件操作接口，即指定文件系統(tǒng) */
    void *data;                         /* 數(shù)據(jù)，指向內(nèi)部數(shù)據(jù)的指針 */
    uint32_t flag;                      /* 節(jié)點標簽 */
    LIST_ENTRY hashEntry;               /* 掛入v_vnodeHashEntry[i]中 */
    LIST_ENTRY actFreeEntry;            /* 通過本節(jié)點掛載到空閑和使用鏈表中 */
    struct Mount *originMount;          /* 所在文件系統(tǒng)掛載信息 */
    struct Mount *newMount;             /* 其他掛載在這個節(jié)點中的文件系統(tǒng)信息 */
    char *filePath;                     /* Vnode的路徑信息 */
    struct page_mapping mapping;        /* page mapping of the vnode */
};

struct VnodeOps {
    int (*Create)(struct Vnode *parent, const char *name, int mode, struct Vnode **vnode);// 創(chuàng)建節(jié)點
    int (*Lookup)(struct Vnode *parent, const char *name, int len, struct Vnode **vnode);// 查詢節(jié)點
    int (*Open)(struct Vnode *vnode, int fd, int mode, int flags);// 打開節(jié)點
    ssize_t (*ReadPage)(struct Vnode *vnode, char *buffer, off_t pos);
    ssize_t (*WritePage)(struct Vnode *vnode, char *buffer, off_t pos, size_t buflen);
    int (*Close)(struct Vnode *vnode);// 關(guān)閉節(jié)點
    int (*Reclaim)(struct Vnode *vnode);// 回收節(jié)點
    int (*Unlink)(struct Vnode *parent, struct Vnode *vnode, const char *fileName);// 取消硬鏈接
    int (*Rmdir)(struct Vnode *parent, struct Vnode *vnode, const char *dirName);// 刪除目錄節(jié)點
    int (*Mkdir)(struct Vnode *parent, const char *dirName, mode_t mode, struct Vnode **vnode);// 創(chuàng)建目錄節(jié)點
    int (*Readdir)(struct Vnode *vnode, struct fs_dirent_s *dir);// 讀目錄節(jié)點信息
    int (*Opendir)(struct Vnode *vnode, struct fs_dirent_s *dir);// 打開目錄節(jié)點
    int (*Rewinddir)(struct Vnode *vnode, struct fs_dirent_s *dir);// 定位目錄節(jié)點
    int (*Closedir)(struct Vnode *vnode, struct fs_dirent_s *dir);// 關(guān)閉目錄節(jié)點
    int (*Getattr)(struct Vnode *vnode, struct stat *st);// 獲取節(jié)點屬性
    int (*Setattr)(struct Vnode *vnode, struct stat *st);// 設(shè)置節(jié)點屬性
    int (*Chattr)(struct Vnode *vnode, struct IATTR *attr);// 改變節(jié)點屬性
    int (*Rename)(struct Vnode *src, struct Vnode *dstParent, const char *srcName, const char *dstName);
    int (*Truncate)(struct Vnode *vnode, off_t len);// 縮小或擴大
    int (*Truncate64)(struct Vnode *vnode, off64_t len);
    int (*Fscheck)(struct Vnode *vnode, struct fs_dirent_s *dir);
    int (*Link)(struct Vnode *src, struct Vnode *dstParent, struct Vnode **dst, const char *dstName);
    int (*Symlink)(struct Vnode *parentVnode, struct Vnode **newVnode, const char *path, const char *target);
    ssize_t (*Readlink)(struct Vnode *vnode, char *buffer, size_t bufLen);
};

int VnodesInit(void)
{
    int retval = LOS_MuxInit(&g_vnodeMux, NULL);
    if (retval != LOS_OK) {
        PRINT_ERR("Create mutex for vnode fail, status: %d", retval);
        return retval;
    }


    LOS_ListInit(&g_vnodeFreeList);
    LOS_ListInit(&g_vnodeVirtualList);
    LOS_ListInit(&g_vnodeActiveList);
    retval = VnodeAlloc(NULL, &g_rootVnode);
    if (retval != LOS_OK) {
        PRINT_ERR("VnodeInit failed error %d
", retval);
        return retval;
    }
    g_rootVnode->mode = S_IRWXU | S_IRWXG | S_IRWXO | S_IFDIR;
    g_rootVnode->type = VNODE_TYPE_DIR;
    g_rootVnode->filePath = "/";


    return LOS_OK;
}

struct Mount {
    LIST_ENTRY mountList;              /* 全局Mount鏈表 */
    const struct MountOps *ops;        /* Mount的功能函數(shù) */
    struct Vnode *vnodeBeCovered;      /* 要被掛載的節(jié)點 */
    struct Vnode *vnodeCovered;        /* 要掛載的節(jié)點 */
    struct Vnode *vnodeDev;            /* 設(shè)備vnode */
    LIST_HEAD vnodeList;               /* Vnode表的表頭 */
    int vnodeSize;                     /* Vnode表的節(jié)點數(shù)量 */
    LIST_HEAD activeVnodeList;         /* 激活的節(jié)點鏈表 */
    int activeVnodeSize;               /* 激活的節(jié)點數(shù)量 */
    void *data;                        /* 數(shù)據(jù)，指向內(nèi)部數(shù)據(jù)的指針 */
    uint32_t hashseed;                 /* Random seed for vfshash */
    unsigned long mountFlags;          /* 掛載標簽 */
    char pathName[PATH_MAX];           /* 掛載點路徑 */
    char devName[PATH_MAX];            /* 設(shè)備名稱 /dev/sdb-1 */
};

struct MountOps {
    int (*Mount)(struct Mount *mount, struct Vnode *vnode, const void *data);
    int (*Unmount)(struct Mount *mount, struct Vnode **blkdriver);
    int (*Statfs)(struct Mount *mount, struct statfs *sbp);//統(tǒng)計文件系統(tǒng)的信息，類型、大小等
    int (*Sync)(struct Mount *mount);
};

struct file
{
  unsigned int         f_magicnum;  /* file magic number. -- to be deleted */
  int                  f_oflags;    /* Open mode flags */
  struct Vnode         *f_vnode;    /* Driver interface */
  loff_t               f_pos;       /* File position */
  unsigned long        f_refcount;  /* reference count */
  char                 *f_path;     /* File fullpath */
  void                 *f_priv;     /* Per file driver private data */
  const char           *f_relpath;  /* realpath.  -- to be deleted */
  struct page_mapping  *f_mapping;  /* mapping file to memory */
  void                 *f_dir;      /* DIR struct for iterate the directory if open a directory */
  const struct file_operations_vfs *ops;
  int fd;
};

struct file_operations_vfs
{
  /* The device driver open method differs from the mountpoint open method */


  int     (*open)(struct file *filep);
  int     (*close)(struct file *filep);
  ssize_t (*read)(struct file *filep, char *buffer, size_t buflen);
  ssize_t (*write)(struct file *filep, const char *buffer, size_t buflen);
  off_t   (*seek)(struct file *filep, off_t offset, int whence);
  int     (*ioctl)(struct file *filep, int cmd, unsigned long arg);
  int     (*mmap)(struct file* filep, struct VmMapRegion *region);
  /* The two structures need not be common after this point */


  int     (*poll)(struct file *filep, poll_table *fds);
  int     (*stat)(struct file *filep, struct stat* st);
  int     (*fallocate)(struct file* filep, int mode, off_t offset, off_t len);
  int     (*fallocate64)(struct file *filep, int mode, off64_t offset, off64_t len);
  int     (*fsync)(struct file *filep);
  ssize_t (*readpage)(struct file *filep, char *buffer, size_t buflen);
  int     (*unlink)(struct Vnode *vnode);
};

const struct MountOps procfs_operations = {
    .Mount = VfsProcfsMount,
    .Unmount = NULL,
    .Statfs = VfsProcfsStatfs,
};


static struct VnodeOps g_procfsVops = {
    .Lookup = VfsProcfsLookup,
    .Getattr = VfsProcfsStat,
    .Readdir = VfsProcfsReaddir,
    .Opendir = VfsProcfsOpendir,
    .Closedir = VfsProcfsClosedir,
    .Truncate = VfsProcfsTruncate
};


static struct file_operations_vfs g_procfsFops = {
    .read = VfsProcfsRead,
    .write = VfsProcfsWrite,
    .open = VfsProcfsOpen,
    .close = VfsProcfsClose
};


// 注冊文件系統(tǒng)名字以及實現(xiàn)的接口方法等
FSMAP_ENTRY(procfs_fsmap,"procfs",procfs_operations,FALSE,FALSE);

// 系統(tǒng)的入口函數(shù)
main(VOID)
|-> OsMain() // ./liteos/kernel/liteos_a/kernel/common/main.c
    | // 進行系統(tǒng)的相關(guān)初始化工作
    | -> EarliestInit()
    | -> ...
    |
    | -> KModInit()
         |-> ...
         |
         |-> OsInitCall(LOS_INIT_LEVEL_KMOD_EXTENDED) // 生成procfs文件系統(tǒng)并掛載到/proc目錄
          |-> InitLevelCall(level)//根據(jù)不同的級別進行相關(guān)初始化工作，procfs的級別是8,其級別是文件系統(tǒng)向OS注冊的
           | // ./liteos/kernel/liteos_a/fs/proc/os_adapt/proc_init.c
           |
           |-> ProcFsInit() // 進行procfs文件系統(tǒng)的具體初始化工作
           | |-> mkdir(PROCFS_MOUNT_POINT, PROCFS_DEFAULT_MODE) // 先生成/proc目錄，之后需要將procfs文件系統(tǒng)掛載到該目錄下
           | |-> mount(NULL, PROCFS_MOUNT_POINT, "procfs", 0, NULL)
           | | // 生成mount文件，包括分配Vnode和掛載Vnode
           | |
           | |-> ProcMountsInit()
           | | | // procfs具體項的初始化都寫在一個獨立的文件中，例如mounts在./liteos/kernel/liteos_a/fs/proc/os_adapt/mounts_proc.c
           | | |
           | | |-> ProcMountsInit(void)
           | | | // 創(chuàng)建mounts節(jié)點并掛載到該目錄下,NULL位parent為父節(jié)點，若parent為NULL，則默認父節(jié)點為/proc
           | | |
           | | |-> CreateProcEntry("mounts", 0, NULL)
           | |  | // 先判斷節(jié)點是文件屬性還是目錄屬性，后選擇具體的節(jié)點創(chuàng)建函數(shù)，在這選擇File節(jié)點
           | |  |
           | |  |-> ProcCreateFile(parent, name, NULL, mode)
           | |   |-> struct ProcDirEntry *pn = NULL
           | |   |-> ProcAllocNode(&parent, name, S_IFREG | mode) // 具體的分配節(jié)點
           | |    |-> struct ProcDirEntry *pn = NULL;
           | |    | // 首先對節(jié)點的合法性進行相關(guān)檢查，例如parent是否NULL，name是否NULL等
           | |    | 
           | |    |-> pn = (struct ProcDirEntry *)malloc(sizeof(struct ProcDirEntry));//分配一個struct ProcDirEntry內(nèi)存地址
           | |    | // 對生成的節(jié)點賦予一些屬性，例如節(jié)點名字長度，權(quán)限，名字等，每個ProcDirEntry都需要指定一個ProcFile成員，里面含有具體信息
           | |    |
           | |    |-> pn->nameLen = strlen(lastName);
           | |    |-> pn->mode = mode;
             | |    |-> ret = memcpy_s(pn->name, sizeof(pn->name), lastName, strlen(lastName) + 1);
             | |    |-> pn->pf = (struct ProcFile *)malloc(sizeof(struct ProcFile));
             | |    |-> pn->pf->pPDE = pn;// ProcFile的parent是生成的pn節(jié)點
             | |   | // 生成對應(yīng)的節(jié)點,對節(jié)點指定相應(yīng)的函數(shù)接口后，需要掛載的父節(jié)點中
             | |   |
             | |   |-> ProcAddNode(parent, pn)
             | |    | // 先判斷parent是否為NULL以及pn是否已經(jīng)有parent，即判斷是否已掛載
             | |    |
             | |    | // 在這里可知一個目錄下的子目錄以及文件都是以一個單鏈表的形式存儲的，且采用的是頭插法，即最先生成的在最后面
             | |    |-> pn->parent = parent;
             | |    |-> pn->next = parent->subdir;
             | |    |-> parent->subdir = pn;
             | |->...
             | |
             | |->ProcPmInit() // 目錄初始化工作
             | | | // power目錄下含有子目錄，但是目錄生成的過程都一樣，在這以power文件夾為例
             | | |-> struct ProcDirEntry *power = CreateProcEntry("power", S_IFDIR | S_IRWXU | S_IRWXG | S_IROTH, NULL);
             | | | |-> CreateProcEntry("power", S_IFDIR | S_IRWXU | S_IRWXG | S_IROTH, NULL)
             | | | | |-> // 先判斷節(jié)點是文件屬性還是目錄屬性，后選擇具體的節(jié)點創(chuàng)建函數(shù)，在這選擇目錄節(jié)點
             | | | | |
             | | | | |-> ProcCreateDir(parent, name, NULL, mode)
             | | | | | | // 這里節(jié)點創(chuàng)建和掛載和上述文件節(jié)點創(chuàng)建一樣，不再贅述
             | | | | | |
             | | | | | |-> ProcAllocNode(&parent, name, S_IFREG | mode) // 具體的分配節(jié)點
             | | | | | |-> ProcAddNode(parent, pn)
             | | | | |
             | | | |
             | | |-> ...
             | |
|...

-> ... 
-> SysMount(const char *source, const char *target, const char *filesystemtype, unsigned long mountflags,const void *data) 
|--|-> 將路徑，文件系統(tǒng)等轉(zhuǎn)化之后調(diào)用mount 
|  |-> mount(sourceRet, targetRet, (filesystemtype ? fstypeRet : NULL), mountflags, dataRet) 
|  |   |-> //找到指定的文件系統(tǒng) 
|  |   |-> fsmap = mount_findfs(filesystemtype) 
|  |   |-> mops = fsmap->fs_mops // 為mount節(jié)點指定mount的接口函數(shù) 
|  |   |-> //找到掛載目錄對應(yīng)的Vnode并且設(shè)置文件系統(tǒng)相關(guān)信息 
|  |   |-> VnodeLookup(target, &mountpt_vnode, 0) 
|  |   |   |->VnodeLookupAt(path, vnode, flags, NULL) 
|  |   |   |  |-> //對目錄變成絕對路徑并且從全局Vnode鏈表中開始找 
|  |   |   |  |-> PreProcess(path, &startVnode, &normalizedPath) 
|  |   |   |  |  |-> vfs_normalize_path(NULL, originPath, &absolutePath) 
|  |   |-> mnt = MountAlloc(mountpt_vnode, (struct MountOps*)mops) 
|  |   |-> mops->Mount(mnt, device, data)//進入具體的procfs文件系統(tǒng)的mount函數(shù) 
|  |   |  |-> VfsProcfsMount(struct Mount *mnt, struct Vnode *device, const void *data) 
|  |   |  |   |-> VnodeAlloc(&g_procfsVops, &vp);//生成一個Vnode用于掛載mount節(jié)點和procfs文件系統(tǒng)的root節(jié)點 
|  |   |  |   |-> root = GetProcRootEntry(); //獲取procfs文件系統(tǒng)的根節(jié)點 
|  |   |  |   |-> vp->data = root; //  
|  |   |  |   |-> vp->originMount = mnt;// 將vp掛載在掛載目錄所對應(yīng)的mount節(jié)點上 
|  |   |  |   |-> mnt->data = NULL; 
|  |   |  |   |-> mnt->vnodeCovered = vp;// mount節(jié)點掛載的Vnode是該文件系統(tǒng)，方便后續(xù)在mount鏈表中找掛載點 
|  |   |  |   |-> vp->type = root->type; 
|||...

   temp = ProcFindNode(parent, pn->name);
    if (temp != NULL) {
        PRINT_ERR("Error!ProcDirEntry '%s/%s' already registered
", parent->name, pn->name);
        spin_unlock(&procfsLock);
        return -EEXIST;
    }
    pn->parent = parent;
    pn->next = parent->subdir;
parent->subdir=pn;

// 定義一個具體的執(zhí)行函數(shù) 
int OsShellCmdWriteProc(int argc, char **argv); 
// 新增命令項 
SHELLCMD_ENTRY(writeproc_shellcmd,CMD_TYPE_EX,"writeproc",XARGS,(CmdCallBackFunc)OsShellCmdWriteProc);

-> ... 
 -> // 使用shell命令喚起writeproc注冊函數(shù) 
 -> writeproc value >> path 
  |-> // 進行初始化工作，主要用于判斷輸入路徑是否合法，節(jié)點是否存在 
  |-> struct ProcDirEntry *handle = NULL; 
  |-> const char *rootProcDir = "/proc/"; 
  |-> handle = OpenProcFile(realPath, O_TRUNC) // 若路徑合法則找到對應(yīng)的Vnode 
  |   |-> pn = ProcFindEntry(fileName) 
  |   |   |-> int leveltotal = 0;// leveltotal用于判定文件所對應(yīng)的層級，一個/表示一層 
  |   |   | // 遍歷Vnode找到對應(yīng)的Vnode并返回 
  |   |-> pn->flags = (unsigned int)(pn->flags) | (unsigned int)flags// 設(shè)置節(jié)點相應(yīng)的權(quán)限 
  |   |-> ... 
  |   WriteProcFile(handle, value, len) // 找到文件句柄之后開始寫入數(shù)據(jù) 
  |   | // 使用Vnode的文件接口對ProcFile數(shù)據(jù)成員進行寫入 
  |   |-> result = pde->procFileOps->write(pde->pf, (const char *)buf, len, &(pde->pf->fPos)) 
|...

pn = &g_procRootDirEntry; 
while ((pn != NULL) && (levelcount < leveltotal)) { 
 levelcount++; 
 isfoundsub = 0; 
 while (pn != NULL) { 
      next = strchr(path, '/'); 
      if (next == NULL) { 
           while (pn != NULL) { 
               if (strcmp(path, pn->name) == 0) { 
                    spin_unlock(&procfsLock); 
                    return pn; 
               } 
               pn = pn->next; 
           } 
           pn = NULL; 
           spin_unlock(&procfsLock); 
           return pn; 
      } 
 
      len = next - path; 
      if (pn == &g_procRootDirEntry) { 
           if (levelcount == leveltotal) { 
               spin_unlock(&procfsLock); 
               return pn; 
           } 
           len = g_procRootDirEntry.nameLen; 
      } 
      if (ProcMatch(len, path, pn)) { 
           isfoundsub = 1; 
           path += len + 1; 
           break; 
      } 
 
      pn = pn->next; 
 } 
}