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212617e63f
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81
libfs.c
81
libfs.c
@ -1,7 +1,3 @@
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/*
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* Custom Filesystem Module - Implements the described behavior for "books" and "authors" directories.
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/fs.h>
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@ -13,6 +9,7 @@
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#include <linux/kernel.h>
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#include <linux/hashtable.h>
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#include <linux/fs_context.h>
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#include <linux/statfs.h>
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#define FS_MAGIC 0x20240615
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#define BOOKS_MODE 01777
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@ -32,7 +29,7 @@ struct link_entry {
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struct inode *target;
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};
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DEFINE_HASHTABLE(link_table, 6); // 64 buckets
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DEFINE_HASHTABLE(link_table, 6);
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static void remove_links_to_inode(struct inode *inode) {
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struct link_entry *entry;
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@ -40,6 +37,7 @@ static void remove_links_to_inode(struct inode *inode) {
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int bkt;
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hash_for_each_safe(link_table, bkt, tmp, entry, node) {
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if (entry->target == inode) {
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printk(KERN_INFO "customfs: removing hardlink to inode %lu\n", inode->i_ino);
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d_delete(entry->link);
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hash_del(&entry->node);
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kfree(entry);
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@ -57,6 +55,16 @@ static void fs_evict_inode(struct inode *inode) {
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clear_inode(inode);
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}
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static int fs_statfs(struct dentry *dentry, struct kstatfs *buf) {
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buf->f_type = FS_MAGIC;
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return 0;
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}
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static const struct super_operations fs_ops = {
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.evict_inode = fs_evict_inode,
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.statfs = fs_statfs,
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};
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static ssize_t books_file_read(struct file *file, char __user *buf, size_t len, loff_t *ppos) {
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return simple_read_from_buffer(buf, len, ppos, file->private_data, PAGE_SIZE);
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}
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@ -78,20 +86,18 @@ static const struct inode_operations books_file_iops = {
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static const struct inode_operations author_subdir_iops;
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static struct dentry *author_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) {
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return simple_lookup(dir, dentry, flags);
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}
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static int author_mkdir(struct user_namespace *ns, struct inode *dir, struct dentry *dentry, umode_t mode) {
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struct inode *inode;
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inode = new_inode(dir->i_sb);
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struct inode *inode = new_inode(dir->i_sb);
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if (!inode)
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return -ENOMEM;
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inode->i_ino = get_next_ino();
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inode_init_owner(ns, inode, dir, S_IFDIR | AUTHOR_SUBDIR_MODE);
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inode_init_owner(&init_user_ns, inode, dir, S_IFDIR | AUTHOR_SUBDIR_MODE);
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inode->i_op = &author_subdir_iops;
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inode->i_fop = &simple_dir_operations;
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inc_nlink(inode);
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inc_nlink(dir);
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d_add(dentry, inode);
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printk(KERN_INFO "customfs: created author subdir '%s'\n", dentry->d_name.name);
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return 0;
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}
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@ -106,22 +112,20 @@ static int author_link(struct dentry *old_dentry, struct inode *dir, struct dent
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entry->link = dget(new_dentry);
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entry->target = inode;
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hash_add(link_table, &entry->node, inode->i_ino);
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printk(KERN_INFO "customfs: created hardlink '%s' to inode %lu\n",
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new_dentry->d_name.name, inode->i_ino);
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}
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}
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return err;
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}
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static const struct inode_operations author_subdir_iops = {
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.lookup = author_lookup,
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.lookup = simple_lookup,
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.mkdir = author_mkdir,
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.rmdir = simple_rmdir,
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.link = author_link,
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};
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static const struct super_operations fs_ops = {
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.evict_inode = fs_evict_inode,
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};
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static struct inode *fs_make_inode(struct super_block *sb, umode_t mode) {
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struct inode *inode = new_inode(sb);
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if (!inode)
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@ -131,9 +135,10 @@ static struct inode *fs_make_inode(struct super_block *sb, umode_t mode) {
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inode->i_sb = sb;
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inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
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if (S_ISDIR(mode) && !inode->i_op) {
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if (S_ISDIR(mode)) {
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inode->i_op = &simple_dir_inode_operations;
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inode->i_fop = &simple_dir_operations;
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inc_nlink(inode);
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} else if (S_ISREG(mode)) {
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inode->i_fop = &books_file_fops;
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inode->i_op = &books_file_iops;
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@ -159,33 +164,55 @@ static int fs_fill_super(struct super_block *sb, void *data, int silent) {
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if (!root_dentry)
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return -ENOMEM;
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sb->s_root = root_dentry;
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books_inode = fs_make_inode(sb, S_IFDIR | BOOKS_MODE);
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if (!books_inode)
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return -ENOMEM;
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goto out_root;
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books_inode->i_op = &simple_dir_inode_operations;
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books_inode->i_fop = &simple_dir_operations;
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books_inode->i_mode |= S_IWUSR | S_IWGRP | S_IWOTH;
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inc_nlink(books_inode);
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books_dentry = d_alloc_name(root_dentry, "books");
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if (!books_dentry)
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return -ENOMEM;
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goto out_books;
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d_add(books_dentry, books_inode);
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d_rehash(books_dentry);
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printk(KERN_INFO "customfs: 'books' directory created\n");
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authors_inode = fs_make_inode(sb, S_IFDIR | AUTHORS_MODE);
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if (!authors_inode)
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return -ENOMEM;
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goto out_books_dentry;
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authors_inode->i_op = &author_subdir_iops;
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inc_nlink(authors_inode);
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authors_dentry = d_alloc_name(root_dentry, "authors");
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if (!authors_dentry)
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return -ENOMEM;
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authors_inode->i_op = &author_subdir_iops;
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goto out_authors;
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d_add(authors_dentry, authors_inode);
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d_rehash(authors_dentry);
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printk(KERN_INFO "customfs: 'authors' directory created\n");
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sb->s_root = root_dentry;
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printk(KERN_INFO "customfs: fill_super completed\n");
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printk(KERN_INFO "customfs: root inode=%lu\n", root_inode->i_ino);
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printk(KERN_INFO "customfs: books inode=%lu\n", books_inode->i_ino);
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printk(KERN_INFO "customfs: authors inode=%lu\n", authors_inode->i_ino);
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return 0;
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out_authors:
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iput(authors_inode);
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out_books_dentry:
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dput(books_dentry);
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out_books:
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iput(books_inode);
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out_root:
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dput(root_dentry);
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iput(root_inode);
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return -ENOMEM;
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}
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static struct dentry *fs_mount(struct file_system_type *type, int flags,
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const char *dev, void *data) {
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printk(KERN_INFO "customfs: mounting\n");
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return mount_nodev(type, flags, data, fs_fill_super);
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}
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@ -198,11 +225,13 @@ static struct file_system_type fs_type = {
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static int __init fs_init(void) {
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hash_init(link_table);
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printk(KERN_INFO "customfs: module loaded\n");
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return register_filesystem(&fs_type);
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}
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static void __exit fs_exit(void) {
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unregister_filesystem(&fs_type);
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printk(KERN_INFO "customfs: module unloaded\n");
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}
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module_init(fs_init);
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23
restart.bash
23
restart.bash
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#!/bin/bash
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set -e
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# Убить все процессы, использующие /mnt/test
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sudo fuser -km /mnt/test || true
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sudo umount /mnt/customfs 2>/dev/null || true
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sudo rmmod libfs 2>/dev/null || true
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# Подождать, пока умрут
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sleep 0.5
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make
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# Умонтировать
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sudo umount /mnt/test || true
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# Выгрузить модуль
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sudo rmmod statsfs || true
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# Подождать, пока освободится
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sleep 0.5
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# Вставить модуль и смонтировать
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sudo insmod statsfs.ko
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sudo mount -t libfs none /mnt/test
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sudo insmod libfs.ko
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sudo mount -t customfs none /mnt/customfs
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ls -l /mnt/customfs
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