path: root/bad/ndevfs.patch

From foo@baz.org Sun Jun  5 14:33:21 2005
Date: Mon, 20 Jun 2005 21:15:16 -0700
To: Greg KH <gregkh@suse.de>
From: Greg Kroah-Hartman <gregkh@suse.de>
Subject: ndevfs: a nano-devfs like fs

You don't really want to run this.  But if you did, here's a simple hack
showing how easy it is to do it.

Note, this patch will NOT be merged into mainline, so don't get your
panties into a bind...


Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 drivers/base/class.c   |    7 +
 fs/Kconfig             |    3 
 fs/Makefile            |    1 
 fs/ndevfs/Makefile     |    4 
 fs/ndevfs/inode.c      |  249 +++++++++++++++++++++++++++++++++++++++++++++++++
 fs/partitions/check.c  |    6 +
 include/linux/ndevfs.h |   13 ++
 7 files changed, 282 insertions(+), 1 deletion(-)

--- gregkh-2.6.orig/drivers/base/class.c
+++ gregkh-2.6/drivers/base/class.c
@@ -18,6 +18,7 @@
 #include <linux/kdev_t.h>
 #include <linux/err.h>
 #include <linux/slab.h>
+#include <linux/ndevfs.h>
 #include "base.h"
 
 #define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)
@@ -577,6 +578,8 @@ int class_device_add(struct class_device
 		attr->show = show_dev;
 		class_device_create_file(class_dev, attr);
 		class_dev->devt_attr = attr;
+
+		ndevfs_create(class_dev->class_id, class_dev->devt, 1);
 	}
 
 	class_device_add_attrs(class_dev);
@@ -700,8 +703,10 @@ void class_device_del(struct class_devic
 		sysfs_remove_link(&class_dev->dev->kobj, class_name);
 	}
 	class_device_remove_file(class_dev, &class_dev->uevent_attr);
-	if (class_dev->devt_attr)
+	if (class_dev->devt_attr) {
 		class_device_remove_file(class_dev, class_dev->devt_attr);
+		ndevfs_remove(class_dev->class_id);
+	}
 	class_device_remove_attrs(class_dev);
 	class_device_remove_groups(class_dev);
 
--- gregkh-2.6.orig/fs/Kconfig
+++ gregkh-2.6/fs/Kconfig
@@ -1815,6 +1815,9 @@ config 9P_FS
 
 	  If unsure, say N.
 
+config NDEV_FS
+	bool "Nano Device File System"
+
 endmenu
 
 menu "Partition Types"
--- gregkh-2.6.orig/fs/Makefile
+++ gregkh-2.6/fs/Makefile
@@ -101,3 +101,4 @@ obj-$(CONFIG_HPPFS)		+= hppfs/
 obj-$(CONFIG_DEBUG_FS)		+= debugfs/
 obj-$(CONFIG_CONFIGFS_FS)	+= configfs/
 obj-$(CONFIG_OCFS2_FS)		+= ocfs2/
+obj-$(CONFIG_NDEV_FS)		+= ndevfs/
--- /dev/null
+++ gregkh-2.6/fs/ndevfs/Makefile
@@ -0,0 +1,4 @@
+ndevfs-objs	:= inode.o
+
+obj-$(CONFIG_NDEV_FS)	+= ndevfs.o
+
--- /dev/null
+++ gregkh-2.6/fs/ndevfs/inode.c
@@ -0,0 +1,249 @@
+/*
+ *  inode.c - part of ndevfs, a tiny little device file system
+ *
+ *  Copyright (C) 2004,2005 Greg Kroah-Hartman <greg@kroah.com>
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License version
+ *	2 as published by the Free Software Foundation.
+ *
+ * Written for all of the people out there who just hate userspace solutions.
+ *
+ */
+
+/* uncomment to get debug messages */
+#define DEBUG
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/pagemap.h>
+#include <linux/init.h>
+#include <linux/namei.h>
+#include <linux/device.h>
+#include <linux/ndevfs.h>
+
+#define MAGIC	0x64756d62
+
+struct entry {
+	struct list_head node;
+	struct dentry *dentry;
+	char name[BUS_ID_SIZE];
+};
+static LIST_HEAD(entries);
+
+static struct vfsmount *mount;
+static int mount_count;
+
+static struct file_operations stupid_file_ops = {
+	.read	= generic_file_read,
+	.write	= generic_file_write,
+	.mmap	= generic_file_mmap,
+	.fsync	= simple_sync_file,
+	.llseek	= generic_file_llseek,
+};
+
+static struct inode *get_inode(struct super_block *sb, int mode, dev_t dev)
+{
+	struct inode *inode = new_inode(sb);
+
+	if (inode) {
+		inode->i_mode = mode;
+		inode->i_uid = 0;
+		inode->i_gid = 0;
+		inode->i_blksize = PAGE_CACHE_SIZE;
+		inode->i_blocks = 0;
+		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+		switch (mode & S_IFMT) {
+		default:
+			init_special_inode(inode, mode, dev);
+			break;
+		case S_IFREG:
+			inode->i_fop = &stupid_file_ops;
+			break;
+		case S_IFDIR:
+			inode->i_op = &simple_dir_inode_operations;
+			inode->i_fop = &simple_dir_operations;
+
+			/* directory inodes start off with i_nlink == 2 (for "." entry) */
+			inode->i_nlink++;
+			break;
+		}
+	}
+	return inode;
+}
+
+/* SMP-safe */
+static int mknod(struct inode *dir, struct dentry *dentry,
+			 int mode, dev_t dev)
+{
+	struct inode *inode = get_inode(dir->i_sb, mode, dev);
+	int error = -EPERM;
+
+	if (dentry->d_inode)
+		return -EEXIST;
+
+	if (inode) {
+		d_instantiate(dentry, inode);
+		dget(dentry);
+		error = 0;
+	}
+	return error;
+}
+
+static inline int positive(struct dentry *dentry)
+{
+	return dentry->d_inode && !d_unhashed(dentry);
+}
+
+static int fill_super(struct super_block *sb, void *data, int silent)
+{
+	static struct tree_descr files[] = {{""}};
+
+	return simple_fill_super(sb, MAGIC, files);
+}
+
+static struct super_block *get_sb(struct file_system_type *fs_type,
+				  int flags, const char *dev_name,
+				  void *data)
+{
+	return get_sb_single(fs_type, flags, data, fill_super);
+}
+
+static void remove(struct dentry *dentry)
+{
+	struct dentry *parent;
+
+	if (!dentry)
+		return;
+
+	parent = dentry->d_parent;
+	if (!parent || !parent->d_inode)
+		return;
+
+	mutex_lock(&parent->d_inode->i_mutex);
+	if (positive(dentry)) {
+		if (dentry->d_inode) {
+			if (S_ISDIR(dentry->d_inode->i_mode))
+				simple_rmdir(parent->d_inode, dentry);
+			else
+				simple_unlink(parent->d_inode, dentry);
+		dput(dentry);
+		}
+	}
+	mutex_unlock(&parent->d_inode->i_mutex);
+	simple_release_fs(&mount, &mount_count);
+}
+
+/**
+ * ndevfs_create - create a device node in ndevfs
+ *
+ * @name: the name to create
+ * @dev: the dev_t of the node
+ * @is_char: if the node is a char device or not
+ */
+void ndevfs_create(const char *name, dev_t dev, int is_char)
+{
+	struct dentry *parent;
+	struct dentry *dentry;
+	struct entry *entry;
+	int err;
+	int mode = S_IRUSR | S_IWUSR;
+
+	pr_debug("ndevfs: creating file '%s' with major %d and minor %d\n",
+		 name, MAJOR(dev), MINOR(dev));
+
+	if (is_char)
+		mode |= S_IFCHR;
+	else
+		mode |= S_IFBLK;
+
+	err = simple_pin_fs("ndevfs", &mount, &mount_count);
+	if (err)
+		return;
+
+	/* everything is at the root fs, no directories allowed */
+	if (mount && mount->mnt_sb) {
+		parent = mount->mnt_sb->s_root;
+	} else {
+		pr_debug("%s: no parent?\n", __FUNCTION__);
+		goto error;
+	}
+
+	mutex_lock(&parent->d_inode->i_mutex);
+	dentry = lookup_one_len(name, parent, strlen(name));
+	if (!IS_ERR(dentry))
+		err = mknod(parent->d_inode, dentry, mode, dev);
+	else
+		err = PTR_ERR(dentry);
+	mutex_unlock(&parent->d_inode->i_mutex);
+
+	if (err)
+		goto error;
+
+	entry = kmalloc(sizeof(struct entry), GFP_KERNEL);
+	if (!entry) {
+		remove(dentry);
+		err = -ENOMEM;
+		goto error;
+	}
+	entry->dentry = dentry;
+	strcpy(&entry->name[0], name);
+	list_add(&entry->node, &entries);
+	return;
+
+error:
+	pr_debug("%s failed with error %d\n", __FUNCTION__, err);
+	simple_release_fs(&mount, &mount_count);
+}
+EXPORT_SYMBOL_GPL(ndevfs_create);
+
+/**
+ * ndevfs_remove - removes the node from the fs
+ *
+ * @name: the name to remove.
+ */
+void ndevfs_remove(const char *name)
+{
+	struct entry *entry;
+	struct dentry *dentry = NULL;
+
+	pr_debug("ndevfs: removing file '%s'\n", name);
+
+	list_for_each_entry(entry, &entries, node) {
+		if (strcmp(name, &entry->name[0]) == 0) {
+			dentry = entry->dentry;
+			break;
+		}
+	}
+	if (!dentry) {
+		pr_debug("%s: can't find %s\n", __FUNCTION__, name);
+		return;
+	}
+	remove (dentry);
+}
+EXPORT_SYMBOL_GPL(ndevfs_remove);
+
+static struct file_system_type fs_type = {
+	.owner =	THIS_MODULE,
+	.name =		"ndevfs",
+	.get_sb =	get_sb,
+	.kill_sb =	kill_litter_super,
+};
+
+static int __init ndevfs_init(void)
+{
+	return register_filesystem(&fs_type);
+}
+
+static void __exit ndevfs_exit(void)
+{
+	simple_release_fs(&mount, &mount_count);
+	unregister_filesystem(&fs_type);
+}
+
+core_initcall(ndevfs_init);
+module_exit(ndevfs_exit);
+MODULE_LICENSE("GPL");
+
--- gregkh-2.6.orig/fs/partitions/check.c
+++ gregkh-2.6/fs/partitions/check.c
@@ -18,6 +18,7 @@
 #include <linux/fs.h>
 #include <linux/kmod.h>
 #include <linux/ctype.h>
+#include <linux/ndevfs.h>
 
 #include "check.h"
 
@@ -321,6 +322,7 @@ void delete_partition(struct gendisk *di
 	p->sectors[0] = p->sectors[1] = 0;
 	if (p->holder_dir)
 		kobject_unregister(p->holder_dir);
+	ndevfs_remove(kobject_name(&p->kobj));
 	kobject_uevent(&p->kobj, KOBJ_REMOVE);
 	kobject_del(&p->kobj);
 	kobject_put(&p->kobj);
@@ -349,6 +351,7 @@ void add_partition(struct gendisk *disk,
 	kobject_add(&p->kobj);
 	if (!disk->part_uevent_suppress)
 		kobject_uevent(&p->kobj, KOBJ_ADD);
+	ndevfs_create(kobject_name(&p->kobj), MKDEV(disk->major, p->partno), 0);
 	partition_sysfs_add_subdir(p);
 	disk->part[part-1] = p;
 }
@@ -404,6 +407,8 @@ void register_disk(struct gendisk *disk)
 		return;
 	disk_sysfs_symlinks(disk);
  	disk_sysfs_add_subdirs(disk);
+	ndevfs_create(kobject_name(&disk->kobj),
+		      MKDEV(disk->major, disk->first_minor), 0);
 
 	/* No minors to use for partitions */
 	if (disk->minors == 1)
@@ -524,6 +529,7 @@ void del_gendisk(struct gendisk *disk)
 		}
 		put_device(disk->driverfs_dev);
 	}
+	ndevfs_remove(kobject_name(&disk->kobj));
 	kobject_uevent(&disk->kobj, KOBJ_REMOVE);
 	kobject_del(&disk->kobj);
 }
--- /dev/null
+++ gregkh-2.6/include/linux/ndevfs.h
@@ -0,0 +1,13 @@
+#ifndef _NDEVFS_H_
+#define _NDEVFS_H_
+
+#if defined(CONFIG_NDEV_FS)
+extern void ndevfs_create(const char *name, dev_t dev, int is_char);
+extern void ndevfs_remove(const char *name);
+#else
+static inline void ndevfs_create(const char *name, dev_t dev, int is_char) {}
+static inline void ndevfs_remove(const char *name) {}
+#endif
+
+#endif
+