1

libfs.c

@@ -1,7 +1,3 @@
-/*
- * Custom Filesystem Module - Implements the described behavior for "books" and "authors" directories.
- */
-
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/fs.h>
@@ -13,6 +9,7 @@
 #include <linux/kernel.h>
 #include <linux/hashtable.h>
 #include <linux/fs_context.h>
+#include <linux/statfs.h>
 
 #define FS_MAGIC 0x20240615
 #define BOOKS_MODE 01777
@@ -32,7 +29,7 @@ struct link_entry {
     struct inode *target;
 };
 
-DEFINE_HASHTABLE(link_table, 6);  // 64 buckets
+DEFINE_HASHTABLE(link_table, 6);
 
 static void remove_links_to_inode(struct inode *inode) {
     struct link_entry *entry;
@@ -40,6 +37,7 @@ static void remove_links_to_inode(struct inode *inode) {
     int bkt;
     hash_for_each_safe(link_table, bkt, tmp, entry, node) {
         if (entry->target == inode) {
+            printk(KERN_INFO "customfs: removing hardlink to inode %lu\n", inode->i_ino);
             d_delete(entry->link);
             hash_del(&entry->node);
             kfree(entry);
@@ -57,6 +55,16 @@ static void fs_evict_inode(struct inode *inode) {
     clear_inode(inode);
 }
 
+static int fs_statfs(struct dentry *dentry, struct kstatfs *buf) {
+    buf->f_type = FS_MAGIC;
+    return 0;
+}
+
+static const struct super_operations fs_ops = {
+    .evict_inode = fs_evict_inode,
+    .statfs = fs_statfs,
+};
+
 static ssize_t books_file_read(struct file *file, char __user *buf, size_t len, loff_t *ppos) {
     return simple_read_from_buffer(buf, len, ppos, file->private_data, PAGE_SIZE);
 }
@@ -78,20 +86,18 @@ static const struct inode_operations books_file_iops = {
 
 static const struct inode_operations author_subdir_iops;
 
-static struct dentry *author_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) {
-    return simple_lookup(dir, dentry, flags);
-}
-
 static int author_mkdir(struct user_namespace *ns, struct inode *dir, struct dentry *dentry, umode_t mode) {
-    struct inode *inode;
+    struct inode *inode = new_inode(dir->i_sb);
-    inode = new_inode(dir->i_sb);
     if (!inode)
         return -ENOMEM;
     inode->i_ino = get_next_ino();
-    inode_init_owner(ns, inode, dir, S_IFDIR | AUTHOR_SUBDIR_MODE);
+    inode_init_owner(&init_user_ns, inode, dir, S_IFDIR | AUTHOR_SUBDIR_MODE);
     inode->i_op = &author_subdir_iops;
     inode->i_fop = &simple_dir_operations;
+    inc_nlink(inode);
+    inc_nlink(dir);
     d_add(dentry, inode);
+    printk(KERN_INFO "customfs: created author subdir '%s'\n", dentry->d_name.name);
     return 0;
 }
 
@@ -106,22 +112,20 @@ static int author_link(struct dentry *old_dentry, struct inode *dir, struct dent
             entry->link = dget(new_dentry);
             entry->target = inode;
             hash_add(link_table, &entry->node, inode->i_ino);
+            printk(KERN_INFO "customfs: created hardlink '%s' to inode %lu\n",
+                   new_dentry->d_name.name, inode->i_ino);
         }
     }
     return err;
 }
 
 static const struct inode_operations author_subdir_iops = {
-    .lookup = author_lookup,
+    .lookup = simple_lookup,
     .mkdir = author_mkdir,
     .rmdir = simple_rmdir,
     .link = author_link,
 };
 
-static const struct super_operations fs_ops = {
-    .evict_inode = fs_evict_inode,
-};
-
 static struct inode *fs_make_inode(struct super_block *sb, umode_t mode) {
     struct inode *inode = new_inode(sb);
     if (!inode)
@@ -131,9 +135,10 @@ static struct inode *fs_make_inode(struct super_block *sb, umode_t mode) {
     inode->i_sb = sb;
     inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
 
-    if (S_ISDIR(mode) && !inode->i_op) {
+    if (S_ISDIR(mode)) {
         inode->i_op = &simple_dir_inode_operations;
         inode->i_fop = &simple_dir_operations;
+        inc_nlink(inode);
     } else if (S_ISREG(mode)) {
         inode->i_fop = &books_file_fops;
         inode->i_op = &books_file_iops;
@@ -159,33 +164,55 @@ static int fs_fill_super(struct super_block *sb, void *data, int silent) {
     if (!root_dentry)
         return -ENOMEM;
 
-    sb->s_root = root_dentry;
-
     books_inode = fs_make_inode(sb, S_IFDIR | BOOKS_MODE);
     if (!books_inode)
-        return -ENOMEM;
+        goto out_root;
     books_inode->i_op = &simple_dir_inode_operations;
     books_inode->i_fop = &simple_dir_operations;
-    books_inode->i_mode |= S_IWUSR | S_IWGRP | S_IWOTH;
+    inc_nlink(books_inode);
     books_dentry = d_alloc_name(root_dentry, "books");
     if (!books_dentry)
-        return -ENOMEM;
+        goto out_books;
     d_add(books_dentry, books_inode);
+    d_rehash(books_dentry);
+    printk(KERN_INFO "customfs: 'books' directory created\n");
 
     authors_inode = fs_make_inode(sb, S_IFDIR | AUTHORS_MODE);
     if (!authors_inode)
-        return -ENOMEM;
+        goto out_books_dentry;
+    authors_inode->i_op = &author_subdir_iops;
+    inc_nlink(authors_inode);
     authors_dentry = d_alloc_name(root_dentry, "authors");
     if (!authors_dentry)
-        return -ENOMEM;
+        goto out_authors;
-    authors_inode->i_op = &author_subdir_iops;
     d_add(authors_dentry, authors_inode);
+    d_rehash(authors_dentry);
+    printk(KERN_INFO "customfs: 'authors' directory created\n");
+
+    sb->s_root = root_dentry;
+
+    printk(KERN_INFO "customfs: fill_super completed\n");
+    printk(KERN_INFO "customfs: root inode=%lu\n", root_inode->i_ino);
+    printk(KERN_INFO "customfs: books inode=%lu\n", books_inode->i_ino);
+    printk(KERN_INFO "customfs: authors inode=%lu\n", authors_inode->i_ino);
 
     return 0;
+
+out_authors:
+    iput(authors_inode);
+out_books_dentry:
+    dput(books_dentry);
+out_books:
+    iput(books_inode);
+out_root:
+    dput(root_dentry);
+    iput(root_inode);
+    return -ENOMEM;
 }
 
 static struct dentry *fs_mount(struct file_system_type *type, int flags,
                                const char *dev, void *data) {
+    printk(KERN_INFO "customfs: mounting\n");
     return mount_nodev(type, flags, data, fs_fill_super);
 }
 
@@ -198,11 +225,13 @@ static struct file_system_type fs_type = {
 
 static int __init fs_init(void) {
     hash_init(link_table);
+    printk(KERN_INFO "customfs: module loaded\n");
     return register_filesystem(&fs_type);
 }
 
 static void __exit fs_exit(void) {
     unregister_filesystem(&fs_type);
+    printk(KERN_INFO "customfs: module unloaded\n");
 }
 
 module_init(fs_init);

restart.bash

@@ -1,21 +1,12 @@
 #!/bin/bash
+
 set -e
 
-# Убить все процессы, использующие /mnt/test
+sudo umount /mnt/customfs 2>/dev/null || true
-sudo fuser -km /mnt/test || true
+sudo rmmod libfs 2>/dev/null || true
 
-# Подождать, пока умрут
+make
-sleep 0.5
 
-# Умонтировать
+sudo insmod libfs.ko
-sudo umount /mnt/test || true
+sudo mount -t customfs none /mnt/customfs
-
+ls -l /mnt/customfs
-# Выгрузить модуль
-sudo rmmod statsfs || true
-
-# Подождать, пока освободится
-sleep 0.5
-
-# Вставить модуль и смонтировать
-sudo insmod statsfs.ko
-sudo mount -t libfs none /mnt/test