dentry

Ordinary files can be created with open or create, FIFO files can be created with pipe, Mknod is mainly used for the creation of device files.In the kernel, Mknod is implemented by Sys_mknod, with the following code:Asmlinkage Long Sys_mknod (const char * filename, int mode, dev_t dev)//For example filename for/tmp/server_socket,dev is the device number {int error = 0;char * tmp;struct dentry * dentry;struc

physical devices (possibly disks, disk partitions, network storage entities, memory, or other media that can store information-even temporarily). In addition to the details of abstracting file operations from the underlying file system, the VFS binds the underlying block device to the available file system. Let's look at the internal structure of the VFS and how it works. The internal structure of the VFS Before looking at the overall architecture of the VFS subsystem, let's look at the main

system, VFS also binds underlying Block devices to available file systems. Let's take a look at the internal structure of VFS and its working principles. Internal Structure of VFS Before viewing the overall architecture of the VFS subsystem, let's take a look at the main objects used. This section explores superblocks, index nodes (or inode), directory entries (or dentry), and file objects. Here, other components are also important, such as cache. H

=sysfs_setattr), which modifies the user's permissions, and so on. The inode structure is as follows: struct Inode { struct Hlist_node i_hash; * * Hash List link/ struct List_head i_list; struct List_head i_sb_list; struct List_head i_dentry; /* Dentry Chain section * * unsigned long I_ino; /* Inode Index * * atomic_t I_count; unsigned int i_nlink; uid_t I_uid; gid_t I_gid; dev_t I_rdev; /* Master Equipment Number * * const struct Inode_operations *i_

There is a d_alloc function in the kernel that allocates a dentry structure and initializes it. /*** D_alloc-allocate a Dcache entry* @parent: Parent of entry to allocate* @name: Qstr of the name** Allocates a dentry. It returns%null if there is insufficient memory* Available. On a success the Dentry is returned. The name passed in* Copied and the copy passed in

Tags: work process hash table using data class cannot integer BubukoInode Management: Inode-cache hash table inode_hashtable Index node cacheManagement of Dentry:We know that several dentry depict a tree-like directory structure, which is the directory structure that the user sees, and each dentry points to an index node (INODE) Structure However, these dentry st

module */_ U32 I _generation;/* index node version number */Union {Void * generic_ip;/* Special file information */} U;};/** Inode_operations of index nodes are defined in Linux/fs. h.*/Struct inode_operations {INT (* Create) (struct inode *, struct dentry *, INT );/* VFS calls this function by calling CREATE () and open () to create a new index node for the dentry object. Use mode to set the initial mode

system, such as file system type, size, all inode objects, Dirty inode lists, and so on.The inode and Super block are actually mapped in the storage medium, where there are also super blocks and inodein the storage medium. However, because of different types of file system differences, the structure of the Super block and the inode varies. The role of VFS is to obtain a super block and inode node in a file system through a specific device driver, and then populate the information in the kernel

not need to make any changes to the kernel part of the API provided by it.Debugfs developers first need to create a directory in the file system. The following function is used to create a directory in the debugfs File System: struct dentry *debugfs_create_dir(const char *name, struct dentry *parent); The parameter name is the name of the directory to be created. The parameter parent specifies t

Kernel File System API d_delete, kernel apid_delete D_delete of Kernel File System API Void d_delete (struct dentry * dentry) is used to delete a dentry. The source code analysis is as follows: void d_delete (struct dentry * dentry) {struct inode * inode; int isdir = 0; /*

, }; /* * Create a file mapping a name to a counter. */ Static struct dentry * lfs_create_file (struct super_block * sb, Struct dentry * dir, const char * name, Atomic_t * counter) { Struct dentry * dentr