Other file systems

Source: Internet
Author: User

Ramfs Memory File System

Ramfs is a memory file system formed by using the VFS structure. Ranfs does not have its own file storage structure, its files are stored in the page cache, the directory structure is described by the Dentry list itself, and the file is described by the VFS inode structure itself.

/proc File System

The/proc file system is a virtual file system that accesses the kernel through the file system interface and outputs the operating state of the system. It provides an interface for communication between the operating system itself and the application process in the form of a file system, enabling the application to safely and conveniently obtain the current health of the system and the internal data information of the kernel, and to modify the configuration information of some systems. For example, you can get the module information and memory information by using the/proc/modules of the module list,/proc/meminfo with memory usage statistics.

Data Structure Proc_dir_entry

In the/proc file system, the structure representing the individual file nodes is the Proc_dir_entry () structure. Similar to Dir_entry () in the file system, it manages the drive from the user control of the operating system to the core space to read and write files. However, unlike a typical file system, it modifies files that are not actually on the hard disk, but that are dynamically created by the kernel in memory after the system is booted. Therefore, after the system shuts down, the files in the/proc file system do not exist.

After the system is started, the file system tree formed by the proc_dir_entry{} structure is created, and the kernel data is dynamically acquired whenever the file under the/proc directory is read from the user space and the core is mapped to the corresponding driver function according to the read file. In addition to providing read kinetic energy, some files of the/proc file system also provide write functionality. This is mainly done for the/proc/sys directory. Writing to the/proc file system does not mean that you need to write hard disk light hard disk devices, but instead dynamically change the data in the kernel to achieve the purpose of monitoring the running state of the kernel, that is, to partially implement debugging functions.

Unlike the Super block of the/proc file system, which does not require the Super block data from the hardware device, it does not need to retrieve the hyper-block data from the system, but initializes the super-blocks directly when the kernel boots, thus completing the initialization process of the/proc file system operation function and the statistical process of the file system.


Other file systems

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