Skip to content
-
Virtual File System
Last Updated :
28 Apr, 2025
The virtual file system is one of the best features of Linux that makes Linux an operating system of choice. Format a pen drive in any Linux flavor operating system and try to see the contents in windows OS. Windows OS does not show anything. What is the problem?
Now try doing the same in windows i.e format a Pendrive in the windows operating system to store some files and then try to view these files through any Linux operating system. we will be able to see the contents. we will also be able to open and read file content easily.
How is that possible? The answer to these questions lies in the concept of the virtual file system that Linux support. VFX is a file system interface for a user process. VFS has the capability of conceiving features and behavior of any file system regardless of processor type memory format as well as hardware.
Two mapping functions are used that transform the properties of the real-time system to the characteristics required by VFS.
Virtual File SystemAs shown in the diagram:
The user process initiates the execution of the system call with the help of the VFS method. VFS interprets this stimulus into an appropriate internal file system call which in turn activates the concerned mapping function of the specified file system.
In the case of an operating system that demands structural changes, all required constructs are created dynamically to meet the requirements. Ex: In FAT-compatible systems, directories are not treated as files so such characteristics are dynamically created since they cannot be mapped. The target file system is then activated to take control so that results can be delivered to the user of the system.
As seen in the above diagram actions and reactions are observed as a role of VFS:
The user initiates a file-oriented system call.
- Kernel calls function in VFS.
- Execution of file system independent manipulation and initiation of target file system call.
- mapping of calls from VFS to the target file system.
- The target file system converts the request into device driver execution.
- Appropriate action is completed as per the guidance of the device driver function and the results are obtained.
- Since VFS objects are implemented as C data structures. Every object is attached with data and pointers.
Primary Types in VFS
- Superblock object: point out specific mount points.
- inode object: Relates specific file.
- Directory: Shows entry to a specific directory.
- File object: Depicts an open file that is used by the process.
1. Tmpfs virtual file system: A virtual file system for Linux called tmpfs stores data in the system's virtual memory. The internal caches of the kernel serve as temporary storage for all files, much like any other virtual file system.
2. Sysfs virtual file system: When a device is added or withdrawn, the sysfs virtual file system dynamically updates the user-specified view of the system's devices. The global, bus, and device discovery levels are represented by the directory hierarchy beneath /sys. The files on the global layer record the device's power state, which is also programmable. The files in the bus layer report details about each device's resources and IRQ number. The file system contains files that a device driver can use to access data or configurable interfaces.
The filesystem type, which is specified in include/linux/fs.h (and abbreviated here for brevity), must be known by the kernel in order to use a filesystem:
Example 1:
C++
struct file_system_type {
const char* name;
int fs_flags;
int (*init_fs_context)(struct fs_context*);
const struct fs_parameter_spec* parameters;
struct dentry* (*mount)(struct file_system_type*, int,
const char*, void*);
void (*kill_sb)(struct super_block*);
struct module* owner;
struct file_system_type* next;
struct hlist_head fs_supers;
};
- struct file_system_type maintains data related to a filesystem but is not associated with any particular 'instance of a filesystem'.
- The userspace command cat /proc/filesystems can be used to inspect the linked list of known filesystem types that the VFS keeps.
- Filesystem types are unregistered and registered in the kernel through these functions in include/linux/fs.h:
- A filesystem of a certain type may be mounted to a place in the directory tree if the kernel is aware of it (i.e., it has been registered).
Similar Reads
Operating System Tutorial An Operating System(OS) is a software that manages and handles hardware and software resources of a computing device. Responsible for managing and controlling all the activities and sharing of computer resources among different running applications.A low-level Software that includes all the basic fu
4 min read
Types of Operating Systems Operating Systems can be categorized according to different criteria like whether an operating system is for mobile devices (examples Android and iOS) or desktop (examples Windows and Linux). Here, we are going to classify based on functionalities an operating system provides.8 Main Operating System
11 min read
Decorators in Python In Python, decorators are a powerful and flexible way to modify or extend the behavior of functions or methods, without changing their actual code. A decorator is essentially a function that takes another function as an argument and returns a new function with enhanced functionality. Decorators are
10 min read
What is an Operating System? An Operating System is a System software that manages all the resources of the computing device. Acts as an interface between the software and different parts of the computer or the computer hardware. Manages the overall resources and operations of the computer. Controls and monitors the execution o
9 min read
CPU Scheduling in Operating Systems CPU scheduling is a process used by the operating system to decide which task or process gets to use the CPU at a particular time. This is important because a CPU can only handle one task at a time, but there are usually many tasks that need to be processed. The following are different purposes of a
8 min read
AVL Tree Data Structure An AVL tree defined as a self-balancing Binary Search Tree (BST) where the difference between heights of left and right subtrees for any node cannot be more than one. Balance Factor = left subtree height - right subtree heightFor a Balanced Tree(for every node): -1 ≤ Balance Factor ≤ 1Example of an
4 min read
What is a Neural Network? Neural networks are machine learning models that mimic the complex functions of the human brain. These models consist of interconnected nodes or neurons that process data, learn patterns and enable tasks such as pattern recognition and decision-making.In this article, we will explore the fundamental
12 min read
Introduction of Deadlock in Operating System A deadlock is a situation where a set of processes is blocked because each process is holding a resource and waiting for another resource acquired by some other process. In this article, we will discuss deadlock, its necessary conditions, etc. in detail.Deadlock is a situation in computing where two
11 min read
Page Replacement Algorithms in Operating Systems In an operating system that uses paging for memory management, a page replacement algorithm is needed to decide which page needs to be replaced when a new page comes in. Page replacement becomes necessary when a page fault occurs and no free page frames are in memory. in this article, we will discus
7 min read
Paging in Operating System Paging is the process of moving parts of a program, called pages, from secondary storage (like a hard drive) into the main memory (RAM). The main idea behind paging is to break a program into smaller fixed-size blocks called pages.To keep track of where each page is stored in memory, the operating s
8 min read
top_of_element && top_of_screen < bottom_of_element) ||
(bottom_of_screen > articleRecommendedTop && top_of_screen < articleRecommendedBottom) ||
(top_of_screen > articleRecommendedBottom)) {
if (!isfollowingApiCall) {
isfollowingApiCall = true;
setTimeout(function(){
if (loginData && loginData.isLoggedIn) {
if (loginData.userName !== $('#followAuthor').val()) {
is_following();
} else {
$('.profileCard-profile-picture').css('background-color', '#E7E7E7');
}
} else {
$('.follow-btn').removeClass('hideIt');
}
}, 3000);
}
}
});
}
$(".accordion-header").click(function() {
var arrowIcon = $(this).find('.bottom-arrow-icon');
arrowIcon.toggleClass('rotate180');
});
});
window.isReportArticle = false;
function report_article(){
if (!loginData || !loginData.isLoggedIn) {
const loginModalButton = $('.login-modal-btn')
if (loginModalButton.length) {
loginModalButton.click();
}
return;
}
if(!window.isReportArticle){
//to add loader
$('.report-loader').addClass('spinner');
jQuery('#report_modal_content').load(gfgSiteUrl+'wp-content/themes/iconic-one/report-modal.php', {
PRACTICE_API_URL: practiceAPIURL,
PRACTICE_URL:practiceURL
},function(responseTxt, statusTxt, xhr){
if(statusTxt == "error"){
alert("Error: " + xhr.status + ": " + xhr.statusText);
}
});
}else{
window.scrollTo({ top: 0, behavior: 'smooth' });
$("#report_modal_content").show();
}
}
function closeShareModal() {
const shareOption = document.querySelector('[data-gfg-action="share-article"]');
shareOption.classList.remove("hover_share_menu");
let shareModal = document.querySelector(".hover__share-modal-container");
shareModal && shareModal.remove();
}
function openShareModal() {
closeShareModal(); // Remove existing modal if any
let shareModal = document.querySelector(".three_dot_dropdown_share");
shareModal.appendChild(Object.assign(document.createElement("div"), { className: "hover__share-modal-container" }));
document.querySelector(".hover__share-modal-container").append(
Object.assign(document.createElement('div'), { className: "share__modal" }),
);
document.querySelector(".share__modal").append(Object.assign(document.createElement('h1'), { className: "share__modal-heading" }, { textContent: "Share to" }));
const socialOptions = ["LinkedIn", "WhatsApp","Twitter", "Copy Link"];
socialOptions.forEach((socialOption) => {
const socialContainer = Object.assign(document.createElement('div'), { className: "social__container" });
const icon = Object.assign(document.createElement("div"), { className: `share__icon share__${socialOption.split(" ").join("")}-icon` });
const socialText = Object.assign(document.createElement("span"), { className: "share__option-text" }, { textContent: `${socialOption}` });
const shareLink = (socialOption === "Copy Link") ?
Object.assign(document.createElement('div'), { role: "button", className: "link-container CopyLink" }) :
Object.assign(document.createElement('a'), { className: "link-container" });
if (socialOption === "LinkedIn") {
shareLink.setAttribute('href', `https://www.linkedin.com/sharing/share-offsite/?url=${window.location.href}`);
shareLink.setAttribute('target', '_blank');
}
if (socialOption === "WhatsApp") {
shareLink.setAttribute('href', `https://api.whatsapp.com/send?text=${window.location.href}`);
shareLink.setAttribute('target', "_blank");
}
if (socialOption === "Twitter") {
shareLink.setAttribute('href', `https://twitter.com/intent/tweet?url=${window.location.href}`);
shareLink.setAttribute('target', "_blank");
}
shareLink.append(icon, socialText);
socialContainer.append(shareLink);
document.querySelector(".share__modal").appendChild(socialContainer);
//adding copy url functionality
if(socialOption === "Copy Link") {
shareLink.addEventListener("click", function() {
var tempInput = document.createElement("input");
tempInput.value = window.location.href;
document.body.appendChild(tempInput);
tempInput.select();
tempInput.setSelectionRange(0, 99999); // For mobile devices
document.execCommand('copy');
document.body.removeChild(tempInput);
this.querySelector(".share__option-text").textContent = "Copied"
})
}
});
// document.querySelector(".hover__share-modal-container").addEventListener("mouseover", () => document.querySelector('[data-gfg-action="share-article"]').classList.add("hover_share_menu"));
}
function toggleLikeElementVisibility(selector, show) {
document.querySelector(`.${selector}`).style.display = show ? "block" : "none";
}
function closeKebabMenu(){
document.getElementById("myDropdown").classList.toggle("show");
}