《操作系统原理与设计 Operating System Principles and Implementation》课程教学课件（英文讲稿）Chapter 9 File Systems part1

OperatingSystemsChapter 9, part 1File Systems - Programmer Perspective

Operating Systems Chapter 9, part 1 File Systems – Programmer Perspective

Story so far...UserSpaceProcessesFile systemImplementationOperatingSystemKernelFAT32,EXT2/3FileSystemOperationsKV,DistributedFSGraphSystem...SCSalid SisDevices25669512G8

Story so far. 2 File System Operations Operating System Kernel User Space Devices Processes File system Implementation FAT32, EXT2/3 KV, Distributed FS, Graph System

Outline· File system introduction. What are stored on a storage device?- File-Directory-Interfaces/Operations3

Outline • File system introduction • What are stored on a storage device? – File – Directory – Interfaces/Operations 3

File system introduction4

4 File system introduction

IntroductionProcessAUserspaceFSOperationsOperatingSystemKernelDevicesTo understand what a file system (Fs) is, we followtwo different, but related directions:Layout&Operations5

Introduction 5 FS Operations Process A Operating System Kernel User space Devices ⚫ To understand what a file system (FS) is, we follow two different, but related directions: - Layout & Operations

IntroductionProcessAUserspaceFSOperationsOperatingSystemKernelThe layout.DevicesEvery Fs has an unique layout on thestorage device. The layout defines:- What are the things stored in the device.-Where the stored things are.6

Introduction 6 FS Operations Process A Operating System Kernel User space The layout. Every FS has an unique layout on the storage device. The layout defines: - What are the things stored in the device. - Where the stored things are. Devices

IntroductionProcessAUserspaceFSOperationsOperatingSystemKernelThe layout.DevicesTheset of FSoperationsdefineshowtheOSshouldworkwiththeFSlayout.Inotherwords,OsknowstheFslayoutand workswiththatlayout

Introduction 7 FS Operations Process A Operating System Kernel User space The layout. Devices The set of FS operations defines how the OS should work with the FS layout. In other words, OS knows the FS layout and works with that layout

IntroductionProcessAUserspaceFSOperationsOperatingSystemKernelThe layout.DevicesThe process uses system calls, whichthen invoke the Fs operations, to accessthe storage device.8

Introduction 8 FS Operations Process A Operating System Kernel User space The layout. Devices The process uses system calls, which then invoke the FS operations, to access the storage device

Introductionfopen()fread()fwrite()fclose()LibraryCallsProcessclose()open()read()write()SystemCallsKernelExt4-FAT32-NTFS-ISO9660-KernelspecificspecificspecificspecificFunctionsfunctionsfunctionsfunctionsfunctionsDevices9

9 Introduction fopen() fread() fwrite() fclose() Library Calls NTFS￾specific functions Ext4- specific functions FAT32- specific functions ISO9660- specific functions Kernel Functions open() read() write() close() System Calls Process Kernel Devices

Summary·Ask yourself:-OS=FS?- Correct answer: OS ± FS-An OS supports a FS: An OS can support more than one FS: AFS can be read by more than one OS10

Summary 10 • Ask yourself: – OS = FS? – Correct answer: OS  FS – An OS supports a FS • An OS can support more than one FS. • A FS can be read by more than one OS