struct inode { struct hlist_node i_hash; //用于散列鏈表 struct list_head i_list; /* backing dev IO list */ struct list_head i_sb_list; struct list_head i_dentry; //援用索引節點的目錄項對象鏈表頭 unsigned long i_ino; //索引節點號 atomic_t i_count; //援用計數器 unsigned int i_nlink; //硬鏈接數目 uid_t i_uid; //所有者標識符 gid_t i_gid; //組標識符 dev_t i_rdev; //實裝備標識符 u64 i_version; //版本號(每次使用后遞增) loff_t i_size; //文件的字節數 #ifdef __NEED_I_SIZE_ORDERED seqcount_t i_size_seqcount; #endif struct timespec i_atime; //上次訪問文件的時間 struct timespec i_mtime; //上次寫文件的時間 struct timespec i_ctime; //上次修改索引節點的時間 blkcnt_t i_blocks; //文件的塊數 unsigned int i_blkbits; //塊的位數 unsigned short i_bytes;//塊的字節數 umode_t i_mode; //文件的類型和訪問權限 spinlock_t i_lock; /* i_blocks, i_bytes, maybe i_size */ struct mutex i_mutex; struct rw_semaphore i_alloc_sem; //在直接I/O文件操作中避免出現競爭條件的讀寫信號量 const struct inode_operations *i_op; //索引節點的操作 const struct file_operations *i_fop; /*缺省文件操作former ->i_op->default_file_ops */ struct super_block *i_sb; //指向超級塊的指針 struct file_lock *i_flock; struct address_space *i_mapping; //指向address_space對象的指針 struct address_space i_data; //文件的address_space對象 #ifdef CONFIG_QUOTA struct dquot *i_dquot[MAXQUOTAS]; //索引節點磁盤限額 #endif struct list_head i_devices; //用于具體的字符或塊裝備索引節點鏈表 union { struct pipe_inode_info *i_pipe; //如果文件是個管道則使用它 struct block_device *i_bdev; //指向塊裝備驅程序的指針 struct cdev *i_cdev; //指向字符裝備驅動程序的指針 }; __u32 i_generation; //索引節點的版本號 #ifdef CONFIG_FSNOTIFY __u32 i_fsnotify_mask; /* all events this inode cares about */ struct hlist_head i_fsnotify_mark_entries; /* fsnotify mark entries */ #endif #ifdef CONFIG_INOTIFY struct list_head inotify_watches; /* watches on this inode */ struct mutex inotify_mutex; /* protects the watches list */ #endif unsigned long i_state; //索引節點狀態標志 unsigned long dirtied_when; /* jiffies of first dirtying */ unsigned int i_flags; //文件系統安裝標志 atomic_t i_writecount; #ifdef CONFIG_SECURITY void *i_security; #endif #ifdef CONFIG_FS_POSIX_ACL struct posix_acl *i_acl; struct posix_acl *i_default_acl; #endif void *i_private; /* fs or device private pointer */ };

struct file { /* * fu_list becomes invalid after file_free is called and queued via * fu_rcuhead for RCU freeing */ union { struct list_head fu_list; struct rcu_head fu_rcuhead; } f_u; struct path f_path; #define f_dentry f_path.dentry //與文件相干的目錄項對象 #define f_vfsmnt f_path.mnt //含有該文件的已安裝文件系統 const struct file_operations *f_op; //文件操作表指針 spinlock_t f_lock; /* f_ep_links, f_flags, no IRQ */ atomic_long_t f_count; //文件對象的援用計數器 unsigned int f_flags; //當打開文件時所指定的標志 fmode_t f_mode; //進程訪問模式 loff_t f_pos; //當前的文件偏移量 struct fown_struct f_owner; //通過信號進行I/O事件通知的數據 const struct cred *f_cred; struct file_ra_state f_ra; //文件預讀狀態 u64 f_version; //版本號，每次使用后自動遞增 #ifdef CONFIG_SECURITY void *f_security; #endif /* needed for tty driver, and maybe others */ void *private_data;//指向特定文件系統或裝備驅動程序所需要數據的指針 #ifdef CONFIG_EPOLL /* Used by fs/eventpoll.c to link all the hooks to this file */ struct list_head f_ep_links;//文件的事件輪詢等待著鏈表頭 #endif /* #ifdef CONFIG_EPOLL */ struct address_space *f_mapping;//指向文件地址空間對象的指針 #ifdef CONFIG_DEBUG_WRITECOUNT unsigned long f_mnt_write_state; #endif };

void __init files_init(unsigned long mempages) { int n; filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); /* * One file with associated inode and dcache is very roughly 1K. * Per default don't use more than 10% of our memory for files. */ n = (mempages * (PAGE_SIZE / 1024)) / 10; files_stat.max_files = n; if (files_stat.max_files < NR_FILE) files_stat.max_files = NR_FILE; files_defer_init(); percpu_counter_init(&nr_files, 0); }

struct dentry { atomic_t d_count; //目錄項對象援用計數 unsigned int d_flags; /* 目錄項高速緩存標志protected by d_lock */ spinlock_t d_lock; /* per dentry lock */ int d_mounted; //對目錄而言，用于記錄安裝該目錄項的文件系統計數器 struct inode *d_inode; /* 與文件名關聯的索引節點Where the name belongs to - NULL is * negative */ /* * The next three fields are touched by __d_lookup. Place them here * so they all fit in a cache line. */ struct hlist_node d_hash; /* lookup hash list */ struct dentry *d_parent; /* 父目錄的目錄項對象parent directory */ struct qstr d_name; //文件名 struct list_head d_lru; /* LRU list */ /* * d_child and d_rcu can share memory */ union { struct list_head d_child; /* child of parent list */ struct rcu_head d_rcu; } d_u; struct list_head d_subdirs; /* our children */ struct list_head d_alias; /* inode alias list */ unsigned long d_time; /* used by d_revalidate */ const struct dentry_operations *d_op;//目錄項方法 struct super_block *d_sb; /* 文件的超級塊對象The root of the dentry tree */ void *d_fsdata; /* 依賴于文件系統的數據fs-specific data */ unsigned char d_iname[DNAME_INLINE_LEN_MIN]; /* small names */ };

struct fs_struct { int users; rwlock_t lock; int umask; //當打開文件設置文件權限是所用的位掩碼 int in_exec; struct path root, pwd; /* 根目錄的目錄項，根目錄所安裝的文件系統對象 當前工作的目錄項，當前工作目錄所安裝的文件系統對象*/ };

struct fdtable { unsigned int max_fds; //文件對象確當前最大數目 struct file ** fd; /* current fd array */ fd_set *close_on_exec; fd_set *open_fds; struct rcu_head rcu; struct fdtable *next; }; /* * Open file table structure */ struct files_struct { /* * read mostly part */ atomic_t count; //同享進程的數目 struct fdtable *fdt; // struct fdtable fdtab; /* * written part on a separate cache line in SMP */ spinlock_t file_lock ____cacheline_aligned_in_smp; int next_fd; struct embedded_fd_set close_on_exec_init; struct embedded_fd_set open_fds_init; struct file * fd_array[NR_OPEN_DEFAULT];//文件對象指針的初始化數組 };

struct file_system_type { const char *name; //文件系統名 int fs_flags; //文件系統標志 int (*get_sb) (struct file_system_type *, int, const char *, void *, struct vfsmount *); //讀取超級塊的方法 void (*kill_sb) (struct super_block *); //刪除超級塊的方法 struct module *owner; //指向實現文件系統的模塊的指針 struct file_system_type * next;//指向文件系統鏈表中下1個元素的指針 struct list_head fs_supers; //具有相同文件系統類型的超級塊對象鏈表頭 struct lock_class_key s_lock_key; struct lock_class_key s_umount_key; struct lock_class_key i_lock_key; struct lock_class_key i_mutex_key; struct lock_class_key i_mutex_dir_key; struct lock_class_key i_alloc_sem_key; };

static struct file_system_type sock_fs_type = { .name = "sockfs", .get_sb = sockfs_get_sb, .kill_sb = kill_anon_super, }; static int __init sock_init(void) { /* * Initialize sock SLAB cache. */ sk_init(); /* * Initialize skbuff SLAB cache */ skb_init(); /* * Initialize the protocols module. */ init_inodecache(); /* 注冊sockfs文件系統 */ register_filesystem(&sock_fs_type); sock_mnt = kern_mount(&sock_fs_type); /* The real protocol initialization is performed in later initcalls. */ #ifdef CONFIG_NETFILTER netfilter_init(); #endif return 0; }