fs/jffs2/super.c - maze/linux - Git at Google

 /*
  * JFFS2 -- Journalling Flash File System, Version 2.
  *
  * Copyright (C) 2001-2003 Red Hat, Inc.
  *
  * Created by David Woodhouse <dwmw2@infradead.org>
  *
  * For licensing information, see the file 'LICENCE' in this directory.
  *
  * $Id: super.c,v 1.106 2005/05/18 11:37:25 dedekind Exp $
  *
  */

 #include <linux/config.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/init.h>
 #include <linux/list.h>
 #include <linux/fs.h>
 #include <linux/mount.h>
 #include <linux/jffs2.h>
 #include <linux/pagemap.h>
 #include <linux/mtd/mtd.h>
 #include <linux/ctype.h>
 #include <linux/namei.h>
 #include "compr.h"
 #include "nodelist.h"

 static void jffs2_put_super(struct super_block *);

 static kmem_cache_t *jffs2_inode_cachep;

 static struct inode *jffs2_alloc_inode(struct super_block *sb)
 {
 	struct jffs2_inode_info *ei;
 	ei = (struct jffs2_inode_info *)kmem_cache_alloc(jffs2_inode_cachep, SLAB_KERNEL);
 	if (!ei)
 		return NULL;
 	return &ei->vfs_inode;
 }

 static void jffs2_destroy_inode(struct inode *inode)
 {
 	kmem_cache_free(jffs2_inode_cachep, JFFS2_INODE_INFO(inode));
 }

 static void jffs2_i_init_once(void * foo, kmem_cache_t * cachep, unsigned long flags)
 {
 	struct jffs2_inode_info *ei = (struct jffs2_inode_info *) foo;

 	if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
 	    SLAB_CTOR_CONSTRUCTOR) {
 		init_MUTEX_LOCKED(&ei->sem);
 		inode_init_once(&ei->vfs_inode);
 	}
 }

 static int jffs2_sync_fs(struct super_block *sb, int wait)
 {
 	struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);

 	down(&c->alloc_sem);
 	jffs2_flush_wbuf_pad(c);
 	up(&c->alloc_sem);
 	return 0;
 }

 static struct super_operations jffs2_super_operations =
 {
 	.alloc_inode =	jffs2_alloc_inode,
 	.destroy_inode =jffs2_destroy_inode,
 	.read_inode =	jffs2_read_inode,
 	.put_super =	jffs2_put_super,
 	.write_super =	jffs2_write_super,
 	.statfs =	jffs2_statfs,
 	.remount_fs =	jffs2_remount_fs,
 	.clear_inode =	jffs2_clear_inode,
 	.dirty_inode =	jffs2_dirty_inode,
 	.sync_fs =	jffs2_sync_fs,
 };

 static int jffs2_sb_compare(struct super_block *sb, void *data)
 {
 	struct jffs2_sb_info *p = data;
 	struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);

 	/* The superblocks are considered to be equivalent if the underlying MTD
 	   device is the same one */
 	if (c->mtd == p->mtd) {
 		D1(printk(KERN_DEBUG "jffs2_sb_compare: match on device %d (\"%s\")\n", p->mtd->index, p->mtd->name));
 		return 1;
 	} else {
 		D1(printk(KERN_DEBUG "jffs2_sb_compare: No match, device %d (\"%s\"), device %d (\"%s\")\n",
 			  c->mtd->index, c->mtd->name, p->mtd->index, p->mtd->name));
 		return 0;
 	}
 }

 static int jffs2_sb_set(struct super_block *sb, void *data)
 {
 	struct jffs2_sb_info *p = data;

 	/* For persistence of NFS exports etc. we use the same s_dev
 	   each time we mount the device, don't just use an anonymous
 	   device */
 	sb->s_fs_info = p;
 	p->os_priv = sb;
 	sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, p->mtd->index);

 	return 0;
 }

 static struct super_block *jffs2_get_sb_mtd(struct file_system_type *fs_type,
 					      int flags, const char *dev_name,
 					      void *data, struct mtd_info *mtd)
 {
 	struct super_block *sb;
 	struct jffs2_sb_info *c;
 	int ret;

 	c = kmalloc(sizeof(*c), GFP_KERNEL);
 	if (!c)
 		return ERR_PTR(-ENOMEM);
 	memset(c, 0, sizeof(*c));
 	c->mtd = mtd;

 	sb = sget(fs_type, jffs2_sb_compare, jffs2_sb_set, c);

 	if (IS_ERR(sb))
 		goto out_put;

 	if (sb->s_root) {
 		/* New mountpoint for JFFS2 which is already mounted */
 		D1(printk(KERN_DEBUG "jffs2_get_sb_mtd(): Device %d (\"%s\") is already mounted\n",
 			  mtd->index, mtd->name));
 		goto out_put;
 	}

 	D1(printk(KERN_DEBUG "jffs2_get_sb_mtd(): New superblock for device %d (\"%s\")\n",
 		  mtd->index, mtd->name));

 	sb->s_op = &jffs2_super_operations;
 	sb->s_flags = flags | MS_NOATIME;

 	ret = jffs2_do_fill_super(sb, data, (flags&MS_VERBOSE)?1:0);

 	if (ret) {
 		/* Failure case... */
 		up_write(&sb->s_umount);
 		deactivate_super(sb);
 		return ERR_PTR(ret);
 	}

 	sb->s_flags |= MS_ACTIVE;
 	return sb;

  out_put:
 	kfree(c);
 	put_mtd_device(mtd);

 	return sb;
 }

 static struct super_block *jffs2_get_sb_mtdnr(struct file_system_type *fs_type,
 					      int flags, const char *dev_name,
 					      void *data, int mtdnr)
 {
 	struct mtd_info *mtd;

 	mtd = get_mtd_device(NULL, mtdnr);
 	if (!mtd) {
 		D1(printk(KERN_DEBUG "jffs2: MTD device #%u doesn't appear to exist\n", mtdnr));
 		return ERR_PTR(-EINVAL);
 	}

 	return jffs2_get_sb_mtd(fs_type, flags, dev_name, data, mtd);
 }

 static struct super_block *jffs2_get_sb(struct file_system_type *fs_type,
 					int flags, const char *dev_name,
 					void *data)
 {
 	int err;
 	struct nameidata nd;
 	int mtdnr;

 	if (!dev_name)
 		return ERR_PTR(-EINVAL);

 	D1(printk(KERN_DEBUG "jffs2_get_sb(): dev_name \"%s\"\n", dev_name));

 	/* The preferred way of mounting in future; especially when
 	   CONFIG_BLK_DEV is implemented - we specify the underlying
 	   MTD device by number or by name, so that we don't require
 	   block device support to be present in the kernel. */

 	/* FIXME: How to do the root fs this way? */

 	if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
 		/* Probably mounting without the blkdev crap */
 		if (dev_name[3] == ':') {
 			struct mtd_info *mtd;

 			/* Mount by MTD device name */
 			D1(printk(KERN_DEBUG "jffs2_get_sb(): mtd:%%s, name \"%s\"\n", dev_name+4));
 			for (mtdnr = 0; mtdnr < MAX_MTD_DEVICES; mtdnr++) {
 				mtd = get_mtd_device(NULL, mtdnr);
 				if (mtd) {
 					if (!strcmp(mtd->name, dev_name+4))
 						return jffs2_get_sb_mtd(fs_type, flags, dev_name, data, mtd);
 					put_mtd_device(mtd);
 				}
 			}
 			printk(KERN_NOTICE "jffs2_get_sb(): MTD device with name \"%s\" not found.\n", dev_name+4);
 		} else if (isdigit(dev_name[3])) {
 			/* Mount by MTD device number name */
 			char *endptr;

 			mtdnr = simple_strtoul(dev_name+3, &endptr, 0);
 			if (!*endptr) {
 				/* It was a valid number */
 				D1(printk(KERN_DEBUG "jffs2_get_sb(): mtd%%d, mtdnr %d\n", mtdnr));
 				return jffs2_get_sb_mtdnr(fs_type, flags, dev_name, data, mtdnr);
 			}
 		}
 	}

 	/* Try the old way - the hack where we allowed users to mount
 	   /dev/mtdblock$(n) but didn't actually _use_ the blkdev */

 	err = path_lookup(dev_name, LOOKUP_FOLLOW, &nd);

 	D1(printk(KERN_DEBUG "jffs2_get_sb(): path_lookup() returned %d, inode %p\n",
 		  err, nd.dentry->d_inode));

 	if (err)
 		return ERR_PTR(err);

 	err = -EINVAL;

 	if (!S_ISBLK(nd.dentry->d_inode->i_mode))
 		goto out;

 	if (nd.mnt->mnt_flags & MNT_NODEV) {
 		err = -EACCES;
 		goto out;
 	}

 	if (imajor(nd.dentry->d_inode) != MTD_BLOCK_MAJOR) {
 		if (!(flags & MS_VERBOSE)) /* Yes I mean this. Strangely */
 			printk(KERN_NOTICE "Attempt to mount non-MTD device \"%s\" as JFFS2\n",
 			       dev_name);
 		goto out;
 	}

 	mtdnr = iminor(nd.dentry->d_inode);
 	path_release(&nd);

 	return jffs2_get_sb_mtdnr(fs_type, flags, dev_name, data, mtdnr);

 out:
 	path_release(&nd);
 	return ERR_PTR(err);
 }

 static void jffs2_put_super (struct super_block *sb)
 {
 	struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);

 	D2(printk(KERN_DEBUG "jffs2: jffs2_put_super()\n"));

 	down(&c->alloc_sem);
 	jffs2_flush_wbuf_pad(c);
 	up(&c->alloc_sem);
 	jffs2_free_ino_caches(c);
 	jffs2_free_raw_node_refs(c);
 	if (c->mtd->flags & MTD_NO_VIRTBLOCKS)
 		vfree(c->blocks);
 	else
 		kfree(c->blocks);
 	jffs2_flash_cleanup(c);
 	kfree(c->inocache_list);
 	if (c->mtd->sync)
 		c->mtd->sync(c->mtd);

 	D1(printk(KERN_DEBUG "jffs2_put_super returning\n"));
 }

 static void jffs2_kill_sb(struct super_block *sb)
 {
 	struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);
 	if (!(sb->s_flags & MS_RDONLY))
 		jffs2_stop_garbage_collect_thread(c);
 	generic_shutdown_super(sb);
 	put_mtd_device(c->mtd);
 	kfree(c);
 }

 static struct file_system_type jffs2_fs_type = {
 	.owner =	THIS_MODULE,
 	.name =		"jffs2",
 	.get_sb =	jffs2_get_sb,
 	.kill_sb =	jffs2_kill_sb,
 };

 static int __init init_jffs2_fs(void)
 {
 	int ret;

 	printk(KERN_INFO "JFFS2 version 2.2."
 #ifdef CONFIG_JFFS2_FS_WRITEBUFFER
 	       " (NAND)"
 #endif
 	       " (C) 2001-2003 Red Hat, Inc.\n");

 	jffs2_inode_cachep = kmem_cache_create("jffs2_i",
 					     sizeof(struct jffs2_inode_info),
 					     0, SLAB_RECLAIM_ACCOUNT,
 					     jffs2_i_init_once, NULL);
 	if (!jffs2_inode_cachep) {
 		printk(KERN_ERR "JFFS2 error: Failed to initialise inode cache\n");
 		return -ENOMEM;
 	}
 	ret = jffs2_compressors_init();
 	if (ret) {
 		printk(KERN_ERR "JFFS2 error: Failed to initialise compressors\n");
 		goto out;
 	}
 	ret = jffs2_create_slab_caches();
 	if (ret) {
 		printk(KERN_ERR "JFFS2 error: Failed to initialise slab caches\n");
 		goto out_compressors;
 	}
 	ret = register_filesystem(&jffs2_fs_type);
 	if (ret) {
 		printk(KERN_ERR "JFFS2 error: Failed to register filesystem\n");
 		goto out_slab;
 	}
 	return 0;

  out_slab:
 	jffs2_destroy_slab_caches();
  out_compressors:
 	jffs2_compressors_exit();
  out:
 	kmem_cache_destroy(jffs2_inode_cachep);
 	return ret;
 }

 static void __exit exit_jffs2_fs(void)
 {
 	unregister_filesystem(&jffs2_fs_type);
 	jffs2_destroy_slab_caches();
 	jffs2_compressors_exit();
 	kmem_cache_destroy(jffs2_inode_cachep);
 }

 module_init(init_jffs2_fs);
 module_exit(exit_jffs2_fs);

 MODULE_DESCRIPTION("The Journalling Flash File System, v2");
 MODULE_AUTHOR("Red Hat, Inc.");
 MODULE_LICENSE("GPL"); // Actually dual-licensed, but it doesn't matter for
 		       // the sake of this tag. It's Free Software.
	/*
	* JFFS2 -- Journalling Flash File System, Version 2.
	*
	* Copyright (C) 2001-2003 Red Hat, Inc.
	*
	* Created by David Woodhouse <dwmw2@infradead.org>
	*
	* For licensing information, see the file 'LICENCE' in this directory.
	*
	* $Id: super.c,v 1.106 2005/05/18 11:37:25 dedekind Exp $
	*
	*/

	#include <linux/config.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/init.h>
	#include <linux/list.h>
	#include <linux/fs.h>
	#include <linux/mount.h>
	#include <linux/jffs2.h>
	#include <linux/pagemap.h>
	#include <linux/mtd/mtd.h>
	#include <linux/ctype.h>
	#include <linux/namei.h>
	#include "compr.h"
	#include "nodelist.h"

	static void jffs2_put_super(struct super_block *);

	static kmem_cache_t *jffs2_inode_cachep;

	static struct inode jffs2_alloc_inode(struct super_block sb)
	{
	struct jffs2_inode_info *ei;
	ei = (struct jffs2_inode_info *)kmem_cache_alloc(jffs2_inode_cachep, SLAB_KERNEL);
	if (!ei)
	return NULL;
	return &ei->vfs_inode;
	}

	static void jffs2_destroy_inode(struct inode *inode)
	{
	kmem_cache_free(jffs2_inode_cachep, JFFS2_INODE_INFO(inode));
	}

	static void jffs2_i_init_once(void * foo, kmem_cache_t * cachep, unsigned long flags)
	{
	struct jffs2_inode_info ei = (struct jffs2_inode_info ) foo;

	if ((flags & (SLAB_CTOR_VERIFY\|SLAB_CTOR_CONSTRUCTOR)) ==
	SLAB_CTOR_CONSTRUCTOR) {
	init_MUTEX_LOCKED(&ei->sem);
	inode_init_once(&ei->vfs_inode);
	}
	}

	static int jffs2_sync_fs(struct super_block *sb, int wait)
	{
	struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);

	down(&c->alloc_sem);
	jffs2_flush_wbuf_pad(c);
	up(&c->alloc_sem);
	return 0;
	}

	static struct super_operations jffs2_super_operations =
	{
	.alloc_inode = jffs2_alloc_inode,
	.destroy_inode =jffs2_destroy_inode,
	.read_inode = jffs2_read_inode,
	.put_super = jffs2_put_super,
	.write_super = jffs2_write_super,
	.statfs = jffs2_statfs,
	.remount_fs = jffs2_remount_fs,
	.clear_inode = jffs2_clear_inode,
	.dirty_inode = jffs2_dirty_inode,
	.sync_fs = jffs2_sync_fs,
	};

	static int jffs2_sb_compare(struct super_block sb, void data)
	{
	struct jffs2_sb_info *p = data;
	struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);

	/* The superblocks are considered to be equivalent if the underlying MTD
	device is the same one */
	if (c->mtd == p->mtd) {
	D1(printk(KERN_DEBUG "jffs2_sb_compare: match on device %d (\"%s\")\n", p->mtd->index, p->mtd->name));
	return 1;
	} else {
	D1(printk(KERN_DEBUG "jffs2_sb_compare: No match, device %d (\"%s\"), device %d (\"%s\")\n",
	c->mtd->index, c->mtd->name, p->mtd->index, p->mtd->name));
	return 0;
	}
	}

	static int jffs2_sb_set(struct super_block sb, void data)
	{
	struct jffs2_sb_info *p = data;

	/* For persistence of NFS exports etc. we use the same s_dev
	each time we mount the device, don't just use an anonymous
	device */
	sb->s_fs_info = p;
	p->os_priv = sb;
	sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, p->mtd->index);

	return 0;
	}

	static struct super_block jffs2_get_sb_mtd(struct file_system_type fs_type,
	int flags, const char *dev_name,
	void data, struct mtd_info mtd)
	{
	struct super_block *sb;
	struct jffs2_sb_info *c;
	int ret;

	c = kmalloc(sizeof(*c), GFP_KERNEL);
	if (!c)
	return ERR_PTR(-ENOMEM);
	memset(c, 0, sizeof(*c));
	c->mtd = mtd;

	sb = sget(fs_type, jffs2_sb_compare, jffs2_sb_set, c);

	if (IS_ERR(sb))
	goto out_put;

	if (sb->s_root) {
	/* New mountpoint for JFFS2 which is already mounted */
	D1(printk(KERN_DEBUG "jffs2_get_sb_mtd(): Device %d (\"%s\") is already mounted\n",
	mtd->index, mtd->name));
	goto out_put;
	}

	D1(printk(KERN_DEBUG "jffs2_get_sb_mtd(): New superblock for device %d (\"%s\")\n",
	mtd->index, mtd->name));

	sb->s_op = &jffs2_super_operations;
	sb->s_flags = flags \| MS_NOATIME;

	ret = jffs2_do_fill_super(sb, data, (flags&MS_VERBOSE)?1:0);

	if (ret) {
	/* Failure case... */
	up_write(&sb->s_umount);
	deactivate_super(sb);
	return ERR_PTR(ret);
	}

	sb->s_flags \|= MS_ACTIVE;
	return sb;

	out_put:
	kfree(c);
	put_mtd_device(mtd);

	return sb;
	}

	static struct super_block jffs2_get_sb_mtdnr(struct file_system_type fs_type,
	int flags, const char *dev_name,
	void *data, int mtdnr)
	{
	struct mtd_info *mtd;

	mtd = get_mtd_device(NULL, mtdnr);
	if (!mtd) {
	D1(printk(KERN_DEBUG "jffs2: MTD device #%u doesn't appear to exist\n", mtdnr));
	return ERR_PTR(-EINVAL);
	}

	return jffs2_get_sb_mtd(fs_type, flags, dev_name, data, mtd);
	}

	static struct super_block jffs2_get_sb(struct file_system_type fs_type,
	int flags, const char *dev_name,
	void *data)
	{
	int err;
	struct nameidata nd;
	int mtdnr;

	if (!dev_name)
	return ERR_PTR(-EINVAL);

	D1(printk(KERN_DEBUG "jffs2_get_sb(): dev_name \"%s\"\n", dev_name));

	/* The preferred way of mounting in future; especially when
	CONFIG_BLK_DEV is implemented - we specify the underlying
	MTD device by number or by name, so that we don't require
	block device support to be present in the kernel. */

	/* FIXME: How to do the root fs this way? */

	if (dev_name[0] == 'm' && dev_name[1] == 't' && dev_name[2] == 'd') {
	/* Probably mounting without the blkdev crap */
	if (dev_name[3] == ':') {
	struct mtd_info *mtd;

	/* Mount by MTD device name */
	D1(printk(KERN_DEBUG "jffs2_get_sb(): mtd:%%s, name \"%s\"\n", dev_name+4));
	for (mtdnr = 0; mtdnr < MAX_MTD_DEVICES; mtdnr++) {
	mtd = get_mtd_device(NULL, mtdnr);
	if (mtd) {
	if (!strcmp(mtd->name, dev_name+4))
	return jffs2_get_sb_mtd(fs_type, flags, dev_name, data, mtd);
	put_mtd_device(mtd);
	}
	}
	printk(KERN_NOTICE "jffs2_get_sb(): MTD device with name \"%s\" not found.\n", dev_name+4);
	} else if (isdigit(dev_name[3])) {
	/* Mount by MTD device number name */
	char *endptr;

	mtdnr = simple_strtoul(dev_name+3, &endptr, 0);
	if (!*endptr) {
	/* It was a valid number */
	D1(printk(KERN_DEBUG "jffs2_get_sb(): mtd%%d, mtdnr %d\n", mtdnr));
	return jffs2_get_sb_mtdnr(fs_type, flags, dev_name, data, mtdnr);
	}
	}
	}

	/* Try the old way - the hack where we allowed users to mount
	/dev/mtdblock$(n) but didn't actually _use_ the blkdev */

	err = path_lookup(dev_name, LOOKUP_FOLLOW, &nd);

	D1(printk(KERN_DEBUG "jffs2_get_sb(): path_lookup() returned %d, inode %p\n",
	err, nd.dentry->d_inode));

	if (err)
	return ERR_PTR(err);

	err = -EINVAL;

	if (!S_ISBLK(nd.dentry->d_inode->i_mode))
	goto out;

	if (nd.mnt->mnt_flags & MNT_NODEV) {
	err = -EACCES;
	goto out;
	}

	if (imajor(nd.dentry->d_inode) != MTD_BLOCK_MAJOR) {
	if (!(flags & MS_VERBOSE)) /* Yes I mean this. Strangely */
	printk(KERN_NOTICE "Attempt to mount non-MTD device \"%s\" as JFFS2\n",
	dev_name);
	goto out;
	}

	mtdnr = iminor(nd.dentry->d_inode);
	path_release(&nd);

	return jffs2_get_sb_mtdnr(fs_type, flags, dev_name, data, mtdnr);

	out:
	path_release(&nd);
	return ERR_PTR(err);
	}

	static void jffs2_put_super (struct super_block *sb)
	{
	struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);

	D2(printk(KERN_DEBUG "jffs2: jffs2_put_super()\n"));

	down(&c->alloc_sem);
	jffs2_flush_wbuf_pad(c);
	up(&c->alloc_sem);
	jffs2_free_ino_caches(c);
	jffs2_free_raw_node_refs(c);
	if (c->mtd->flags & MTD_NO_VIRTBLOCKS)
	vfree(c->blocks);
	else
	kfree(c->blocks);
	jffs2_flash_cleanup(c);
	kfree(c->inocache_list);
	if (c->mtd->sync)
	c->mtd->sync(c->mtd);

	D1(printk(KERN_DEBUG "jffs2_put_super returning\n"));
	}

	static void jffs2_kill_sb(struct super_block *sb)
	{
	struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);
	if (!(sb->s_flags & MS_RDONLY))
	jffs2_stop_garbage_collect_thread(c);
	generic_shutdown_super(sb);
	put_mtd_device(c->mtd);
	kfree(c);
	}

	static struct file_system_type jffs2_fs_type = {
	.owner = THIS_MODULE,
	.name = "jffs2",
	.get_sb = jffs2_get_sb,
	.kill_sb = jffs2_kill_sb,
	};

	static int __init init_jffs2_fs(void)
	{
	int ret;

	printk(KERN_INFO "JFFS2 version 2.2."
	#ifdef CONFIG_JFFS2_FS_WRITEBUFFER
	" (NAND)"
	#endif
	" (C) 2001-2003 Red Hat, Inc.\n");

	jffs2_inode_cachep = kmem_cache_create("jffs2_i",
	sizeof(struct jffs2_inode_info),
	0, SLAB_RECLAIM_ACCOUNT,
	jffs2_i_init_once, NULL);
	if (!jffs2_inode_cachep) {
	printk(KERN_ERR "JFFS2 error: Failed to initialise inode cache\n");
	return -ENOMEM;
	}
	ret = jffs2_compressors_init();
	if (ret) {
	printk(KERN_ERR "JFFS2 error: Failed to initialise compressors\n");
	goto out;
	}
	ret = jffs2_create_slab_caches();
	if (ret) {
	printk(KERN_ERR "JFFS2 error: Failed to initialise slab caches\n");
	goto out_compressors;
	}
	ret = register_filesystem(&jffs2_fs_type);
	if (ret) {
	printk(KERN_ERR "JFFS2 error: Failed to register filesystem\n");
	goto out_slab;
	}
	return 0;

	out_slab:
	jffs2_destroy_slab_caches();
	out_compressors:
	jffs2_compressors_exit();
	out:
	kmem_cache_destroy(jffs2_inode_cachep);
	return ret;
	}

	static void __exit exit_jffs2_fs(void)
	{
	unregister_filesystem(&jffs2_fs_type);
	jffs2_destroy_slab_caches();
	jffs2_compressors_exit();
	kmem_cache_destroy(jffs2_inode_cachep);
	}

	module_init(init_jffs2_fs);
	module_exit(exit_jffs2_fs);

	MODULE_DESCRIPTION("The Journalling Flash File System, v2");
	MODULE_AUTHOR("Red Hat, Inc.");
	MODULE_LICENSE("GPL"); // Actually dual-licensed, but it doesn't matter for
	// the sake of this tag. It's Free Software.