fs/fuse/inode.c - kernel/msm-4.19 - Gitiles

 /*
   FUSE: Filesystem in Userspace
   Copyright (C) 2001-2006  Miklos Szeredi <miklos@szeredi.hu>

   This program can be distributed under the terms of the GNU GPL.
   See the file COPYING.
 */

 #include "fuse_i.h"

 #include <linux/pagemap.h>
 #include <linux/slab.h>
 #include <linux/file.h>
 #include <linux/seq_file.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/parser.h>
 #include <linux/statfs.h>
 #include <linux/random.h>

 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
 MODULE_DESCRIPTION("Filesystem in Userspace");
 MODULE_LICENSE("GPL");

 static struct kmem_cache *fuse_inode_cachep;
 struct list_head fuse_conn_list;
 DEFINE_MUTEX(fuse_mutex);

 #define FUSE_SUPER_MAGIC 0x65735546

 struct fuse_mount_data {
 	int fd;
 	unsigned rootmode;
 	unsigned user_id;
 	unsigned group_id;
 	unsigned fd_present : 1;
 	unsigned rootmode_present : 1;
 	unsigned user_id_present : 1;
 	unsigned group_id_present : 1;
 	unsigned flags;
 	unsigned max_read;
 	unsigned blksize;
 };

 static struct inode *fuse_alloc_inode(struct super_block *sb)
 {
 	struct inode *inode;
 	struct fuse_inode *fi;

 	inode = kmem_cache_alloc(fuse_inode_cachep, GFP_KERNEL);
 	if (!inode)
 		return NULL;

 	fi = get_fuse_inode(inode);
 	fi->i_time = 0;
 	fi->nodeid = 0;
 	fi->nlookup = 0;
 	fi->forget_req = fuse_request_alloc();
 	if (!fi->forget_req) {
 		kmem_cache_free(fuse_inode_cachep, inode);
 		return NULL;
 	}

 	return inode;
 }

 static void fuse_destroy_inode(struct inode *inode)
 {
 	struct fuse_inode *fi = get_fuse_inode(inode);
 	if (fi->forget_req)
 		fuse_request_free(fi->forget_req);
 	kmem_cache_free(fuse_inode_cachep, inode);
 }

 static void fuse_read_inode(struct inode *inode)
 {
 	/* No op */
 }

 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
 		      unsigned long nodeid, u64 nlookup)
 {
 	struct fuse_forget_in *inarg = &req->misc.forget_in;
 	inarg->nlookup = nlookup;
 	req->in.h.opcode = FUSE_FORGET;
 	req->in.h.nodeid = nodeid;
 	req->in.numargs = 1;
 	req->in.args[0].size = sizeof(struct fuse_forget_in);
 	req->in.args[0].value = inarg;
 	request_send_noreply(fc, req);
 }

 static void fuse_clear_inode(struct inode *inode)
 {
 	if (inode->i_sb->s_flags & MS_ACTIVE) {
 		struct fuse_conn *fc = get_fuse_conn(inode);
 		struct fuse_inode *fi = get_fuse_inode(inode);
 		fuse_send_forget(fc, fi->forget_req, fi->nodeid, fi->nlookup);
 		fi->forget_req = NULL;
 	}
 }

 static int fuse_remount_fs(struct super_block *sb, int *flags, char *data)
 {
 	if (*flags & MS_MANDLOCK)
 		return -EINVAL;

 	return 0;
 }

 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr)
 {
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	if (S_ISREG(inode->i_mode) && i_size_read(inode) != attr->size)
 		invalidate_mapping_pages(inode->i_mapping, 0, -1);

 	inode->i_ino     = attr->ino;
 	inode->i_mode    = (inode->i_mode & S_IFMT) + (attr->mode & 07777);
 	inode->i_nlink   = attr->nlink;
 	inode->i_uid     = attr->uid;
 	inode->i_gid     = attr->gid;
 	spin_lock(&fc->lock);
 	i_size_write(inode, attr->size);
 	spin_unlock(&fc->lock);
 	inode->i_blocks  = attr->blocks;
 	inode->i_atime.tv_sec   = attr->atime;
 	inode->i_atime.tv_nsec  = attr->atimensec;
 	inode->i_mtime.tv_sec   = attr->mtime;
 	inode->i_mtime.tv_nsec  = attr->mtimensec;
 	inode->i_ctime.tv_sec   = attr->ctime;
 	inode->i_ctime.tv_nsec  = attr->ctimensec;
 }

 static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
 {
 	inode->i_mode = attr->mode & S_IFMT;
 	inode->i_size = attr->size;
 	if (S_ISREG(inode->i_mode)) {
 		fuse_init_common(inode);
 		fuse_init_file_inode(inode);
 	} else if (S_ISDIR(inode->i_mode))
 		fuse_init_dir(inode);
 	else if (S_ISLNK(inode->i_mode))
 		fuse_init_symlink(inode);
 	else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
 		 S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
 		fuse_init_common(inode);
 		init_special_inode(inode, inode->i_mode,
 				   new_decode_dev(attr->rdev));
 	} else
 		BUG();
 }

 static int fuse_inode_eq(struct inode *inode, void *_nodeidp)
 {
 	unsigned long nodeid = *(unsigned long *) _nodeidp;
 	if (get_node_id(inode) == nodeid)
 		return 1;
 	else
 		return 0;
 }

 static int fuse_inode_set(struct inode *inode, void *_nodeidp)
 {
 	unsigned long nodeid = *(unsigned long *) _nodeidp;
 	get_fuse_inode(inode)->nodeid = nodeid;
 	return 0;
 }

 struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
 			int generation, struct fuse_attr *attr)
 {
 	struct inode *inode;
 	struct fuse_inode *fi;
 	struct fuse_conn *fc = get_fuse_conn_super(sb);

  retry:
 	inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);
 	if (!inode)
 		return NULL;

 	if ((inode->i_state & I_NEW)) {
 		inode->i_flags |= S_NOATIME|S_NOCMTIME;
 		inode->i_generation = generation;
 		inode->i_data.backing_dev_info = &fc->bdi;
 		fuse_init_inode(inode, attr);
 		unlock_new_inode(inode);
 	} else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
 		/* Inode has changed type, any I/O on the old should fail */
 		make_bad_inode(inode);
 		iput(inode);
 		goto retry;
 	}

 	fi = get_fuse_inode(inode);
 	spin_lock(&fc->lock);
 	fi->nlookup ++;
 	spin_unlock(&fc->lock);
 	fuse_change_attributes(inode, attr);
 	return inode;
 }

 static void fuse_umount_begin(struct vfsmount *vfsmnt, int flags)
 {
 	if (flags & MNT_FORCE)
 		fuse_abort_conn(get_fuse_conn_super(vfsmnt->mnt_sb));
 }

 static void fuse_send_destroy(struct fuse_conn *fc)
 {
 	struct fuse_req *req = fc->destroy_req;
 	if (req && fc->conn_init) {
 		fc->destroy_req = NULL;
 		req->in.h.opcode = FUSE_DESTROY;
 		req->force = 1;
 		request_send(fc, req);
 		fuse_put_request(fc, req);
 	}
 }

 static void fuse_put_super(struct super_block *sb)
 {
 	struct fuse_conn *fc = get_fuse_conn_super(sb);

 	fuse_send_destroy(fc);
 	spin_lock(&fc->lock);
 	fc->connected = 0;
 	fc->blocked = 0;
 	spin_unlock(&fc->lock);
 	/* Flush all readers on this fs */
 	kill_fasync(&fc->fasync, SIGIO, POLL_IN);
 	wake_up_all(&fc->waitq);
 	wake_up_all(&fc->blocked_waitq);
 	mutex_lock(&fuse_mutex);
 	list_del(&fc->entry);
 	fuse_ctl_remove_conn(fc);
 	mutex_unlock(&fuse_mutex);
 	fuse_conn_put(fc);
 }

 static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
 {
 	stbuf->f_type    = FUSE_SUPER_MAGIC;
 	stbuf->f_bsize   = attr->bsize;
 	stbuf->f_frsize  = attr->frsize;
 	stbuf->f_blocks  = attr->blocks;
 	stbuf->f_bfree   = attr->bfree;
 	stbuf->f_bavail  = attr->bavail;
 	stbuf->f_files   = attr->files;
 	stbuf->f_ffree   = attr->ffree;
 	stbuf->f_namelen = attr->namelen;
 	/* fsid is left zero */
 }

 static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	struct super_block *sb = dentry->d_sb;
 	struct fuse_conn *fc = get_fuse_conn_super(sb);
 	struct fuse_req *req;
 	struct fuse_statfs_out outarg;
 	int err;

 	req = fuse_get_req(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);

 	memset(&outarg, 0, sizeof(outarg));
 	req->in.numargs = 0;
 	req->in.h.opcode = FUSE_STATFS;
 	req->in.h.nodeid = get_node_id(dentry->d_inode);
 	req->out.numargs = 1;
 	req->out.args[0].size =
 		fc->minor < 4 ? FUSE_COMPAT_STATFS_SIZE : sizeof(outarg);
 	req->out.args[0].value = &outarg;
 	request_send(fc, req);
 	err = req->out.h.error;
 	if (!err)
 		convert_fuse_statfs(buf, &outarg.st);
 	fuse_put_request(fc, req);
 	return err;
 }

 enum {
 	OPT_FD,
 	OPT_ROOTMODE,
 	OPT_USER_ID,
 	OPT_GROUP_ID,
 	OPT_DEFAULT_PERMISSIONS,
 	OPT_ALLOW_OTHER,
 	OPT_MAX_READ,
 	OPT_BLKSIZE,
 	OPT_ERR
 };

 static match_table_t tokens = {
 	{OPT_FD,			"fd=%u"},
 	{OPT_ROOTMODE,			"rootmode=%o"},
 	{OPT_USER_ID,			"user_id=%u"},
 	{OPT_GROUP_ID,			"group_id=%u"},
 	{OPT_DEFAULT_PERMISSIONS,	"default_permissions"},
 	{OPT_ALLOW_OTHER,		"allow_other"},
 	{OPT_MAX_READ,			"max_read=%u"},
 	{OPT_BLKSIZE,			"blksize=%u"},
 	{OPT_ERR,			NULL}
 };

 static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev)
 {
 	char *p;
 	memset(d, 0, sizeof(struct fuse_mount_data));
 	d->max_read = ~0;
 	d->blksize = 512;

 	while ((p = strsep(&opt, ",")) != NULL) {
 		int token;
 		int value;
 		substring_t args[MAX_OPT_ARGS];
 		if (!*p)
 			continue;

 		token = match_token(p, tokens, args);
 		switch (token) {
 		case OPT_FD:
 			if (match_int(&args[0], &value))
 				return 0;
 			d->fd = value;
 			d->fd_present = 1;
 			break;

 		case OPT_ROOTMODE:
 			if (match_octal(&args[0], &value))
 				return 0;
 			if (!fuse_valid_type(value))
 				return 0;
 			d->rootmode = value;
 			d->rootmode_present = 1;
 			break;

 		case OPT_USER_ID:
 			if (match_int(&args[0], &value))
 				return 0;
 			d->user_id = value;
 			d->user_id_present = 1;
 			break;

 		case OPT_GROUP_ID:
 			if (match_int(&args[0], &value))
 				return 0;
 			d->group_id = value;
 			d->group_id_present = 1;
 			break;

 		case OPT_DEFAULT_PERMISSIONS:
 			d->flags |= FUSE_DEFAULT_PERMISSIONS;
 			break;

 		case OPT_ALLOW_OTHER:
 			d->flags |= FUSE_ALLOW_OTHER;
 			break;

 		case OPT_MAX_READ:
 			if (match_int(&args[0], &value))
 				return 0;
 			d->max_read = value;
 			break;

 		case OPT_BLKSIZE:
 			if (!is_bdev || match_int(&args[0], &value))
 				return 0;
 			d->blksize = value;
 			break;

 		default:
 			return 0;
 		}
 	}

 	if (!d->fd_present || !d->rootmode_present ||
 	    !d->user_id_present || !d->group_id_present)
 		return 0;

 	return 1;
 }

 static int fuse_show_options(struct seq_file *m, struct vfsmount *mnt)
 {
 	struct fuse_conn *fc = get_fuse_conn_super(mnt->mnt_sb);

 	seq_printf(m, ",user_id=%u", fc->user_id);
 	seq_printf(m, ",group_id=%u", fc->group_id);
 	if (fc->flags & FUSE_DEFAULT_PERMISSIONS)
 		seq_puts(m, ",default_permissions");
 	if (fc->flags & FUSE_ALLOW_OTHER)
 		seq_puts(m, ",allow_other");
 	if (fc->max_read != ~0)
 		seq_printf(m, ",max_read=%u", fc->max_read);
 	return 0;
 }

 static struct fuse_conn *new_conn(void)
 {
 	struct fuse_conn *fc;

 	fc = kzalloc(sizeof(*fc), GFP_KERNEL);
 	if (fc) {
 		spin_lock_init(&fc->lock);
 		mutex_init(&fc->inst_mutex);
 		atomic_set(&fc->count, 1);
 		init_waitqueue_head(&fc->waitq);
 		init_waitqueue_head(&fc->blocked_waitq);
 		INIT_LIST_HEAD(&fc->pending);
 		INIT_LIST_HEAD(&fc->processing);
 		INIT_LIST_HEAD(&fc->io);
 		INIT_LIST_HEAD(&fc->interrupts);
 		atomic_set(&fc->num_waiting, 0);
 		fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
 		fc->bdi.unplug_io_fn = default_unplug_io_fn;
 		fc->reqctr = 0;
 		fc->blocked = 1;
 		get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));
 	}
 	return fc;
 }

 void fuse_conn_put(struct fuse_conn *fc)
 {
 	if (atomic_dec_and_test(&fc->count)) {
 		if (fc->destroy_req)
 			fuse_request_free(fc->destroy_req);
 		mutex_destroy(&fc->inst_mutex);
 		kfree(fc);
 	}
 }

 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc)
 {
 	atomic_inc(&fc->count);
 	return fc;
 }

 static struct inode *get_root_inode(struct super_block *sb, unsigned mode)
 {
 	struct fuse_attr attr;
 	memset(&attr, 0, sizeof(attr));

 	attr.mode = mode;
 	attr.ino = FUSE_ROOT_ID;
 	return fuse_iget(sb, 1, 0, &attr);
 }

 static const struct super_operations fuse_super_operations = {
 	.alloc_inode    = fuse_alloc_inode,
 	.destroy_inode  = fuse_destroy_inode,
 	.read_inode	= fuse_read_inode,
 	.clear_inode	= fuse_clear_inode,
 	.remount_fs	= fuse_remount_fs,
 	.put_super	= fuse_put_super,
 	.umount_begin	= fuse_umount_begin,
 	.statfs		= fuse_statfs,
 	.show_options	= fuse_show_options,
 };

 static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
 {
 	struct fuse_init_out *arg = &req->misc.init_out;

 	if (req->out.h.error || arg->major != FUSE_KERNEL_VERSION)
 		fc->conn_error = 1;
 	else {
 		unsigned long ra_pages;

 		if (arg->minor >= 6) {
 			ra_pages = arg->max_readahead / PAGE_CACHE_SIZE;
 			if (arg->flags & FUSE_ASYNC_READ)
 				fc->async_read = 1;
 			if (!(arg->flags & FUSE_POSIX_LOCKS))
 				fc->no_lock = 1;
 		} else {
 			ra_pages = fc->max_read / PAGE_CACHE_SIZE;
 			fc->no_lock = 1;
 		}

 		fc->bdi.ra_pages = min(fc->bdi.ra_pages, ra_pages);
 		fc->minor = arg->minor;
 		fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
 		fc->conn_init = 1;
 	}
 	fuse_put_request(fc, req);
 	fc->blocked = 0;
 	wake_up_all(&fc->blocked_waitq);
 }

 static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
 {
 	struct fuse_init_in *arg = &req->misc.init_in;

 	arg->major = FUSE_KERNEL_VERSION;
 	arg->minor = FUSE_KERNEL_MINOR_VERSION;
 	arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
 	arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS;
 	req->in.h.opcode = FUSE_INIT;
 	req->in.numargs = 1;
 	req->in.args[0].size = sizeof(*arg);
 	req->in.args[0].value = arg;
 	req->out.numargs = 1;
 	/* Variable length arguement used for backward compatibility
 	   with interface version < 7.5.  Rest of init_out is zeroed
 	   by do_get_request(), so a short reply is not a problem */
 	req->out.argvar = 1;
 	req->out.args[0].size = sizeof(struct fuse_init_out);
 	req->out.args[0].value = &req->misc.init_out;
 	req->end = process_init_reply;
 	request_send_background(fc, req);
 }

 static u64 conn_id(void)
 {
 	static u64 ctr = 1;
 	return ctr++;
 }

 static int fuse_fill_super(struct super_block *sb, void *data, int silent)
 {
 	struct fuse_conn *fc;
 	struct inode *root;
 	struct fuse_mount_data d;
 	struct file *file;
 	struct dentry *root_dentry;
 	struct fuse_req *init_req;
 	int err;
 	int is_bdev = sb->s_bdev != NULL;

 	if (sb->s_flags & MS_MANDLOCK)
 		return -EINVAL;

 	if (!parse_fuse_opt((char *) data, &d, is_bdev))
 		return -EINVAL;

 	if (is_bdev) {
 #ifdef CONFIG_BLOCK
 		if (!sb_set_blocksize(sb, d.blksize))
 			return -EINVAL;
 #endif
 	} else {
 		sb->s_blocksize = PAGE_CACHE_SIZE;
 		sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 	}
 	sb->s_magic = FUSE_SUPER_MAGIC;
 	sb->s_op = &fuse_super_operations;
 	sb->s_maxbytes = MAX_LFS_FILESIZE;

 	file = fget(d.fd);
 	if (!file)
 		return -EINVAL;

 	if (file->f_op != &fuse_dev_operations)
 		return -EINVAL;

 	fc = new_conn();
 	if (!fc)
 		return -ENOMEM;

 	fc->flags = d.flags;
 	fc->user_id = d.user_id;
 	fc->group_id = d.group_id;
 	fc->max_read = d.max_read;

 	/* Used by get_root_inode() */
 	sb->s_fs_info = fc;

 	err = -ENOMEM;
 	root = get_root_inode(sb, d.rootmode);
 	if (!root)
 		goto err;

 	root_dentry = d_alloc_root(root);
 	if (!root_dentry) {
 		iput(root);
 		goto err;
 	}

 	init_req = fuse_request_alloc();
 	if (!init_req)
 		goto err_put_root;

 	if (is_bdev) {
 		fc->destroy_req = fuse_request_alloc();
 		if (!fc->destroy_req)
 			goto err_put_root;
 	}

 	mutex_lock(&fuse_mutex);
 	err = -EINVAL;
 	if (file->private_data)
 		goto err_unlock;

 	fc->id = conn_id();
 	err = fuse_ctl_add_conn(fc);
 	if (err)
 		goto err_unlock;

 	list_add_tail(&fc->entry, &fuse_conn_list);
 	sb->s_root = root_dentry;
 	fc->connected = 1;
 	file->private_data = fuse_conn_get(fc);
 	mutex_unlock(&fuse_mutex);
 	/*
 	 * atomic_dec_and_test() in fput() provides the necessary
 	 * memory barrier for file->private_data to be visible on all
 	 * CPUs after this
 	 */
 	fput(file);

 	fuse_send_init(fc, init_req);

 	return 0;

  err_unlock:
 	mutex_unlock(&fuse_mutex);
 	fuse_request_free(init_req);
  err_put_root:
 	dput(root_dentry);
  err:
 	fput(file);
 	fuse_conn_put(fc);
 	return err;
 }

 static int fuse_get_sb(struct file_system_type *fs_type,
 		       int flags, const char *dev_name,
 		       void *raw_data, struct vfsmount *mnt)
 {
 	return get_sb_nodev(fs_type, flags, raw_data, fuse_fill_super, mnt);
 }

 static struct file_system_type fuse_fs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "fuse",
 	.get_sb		= fuse_get_sb,
 	.kill_sb	= kill_anon_super,
 };

 #ifdef CONFIG_BLOCK
 static int fuse_get_sb_blk(struct file_system_type *fs_type,
 			   int flags, const char *dev_name,
 			   void *raw_data, struct vfsmount *mnt)
 {
 	return get_sb_bdev(fs_type, flags, dev_name, raw_data, fuse_fill_super,
 			   mnt);
 }

 static struct file_system_type fuseblk_fs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "fuseblk",
 	.get_sb		= fuse_get_sb_blk,
 	.kill_sb	= kill_block_super,
 	.fs_flags	= FS_REQUIRES_DEV,
 };

 static inline int register_fuseblk(void)
 {
 	return register_filesystem(&fuseblk_fs_type);
 }

 static inline void unregister_fuseblk(void)
 {
 	unregister_filesystem(&fuseblk_fs_type);
 }
 #else
 static inline int register_fuseblk(void)
 {
 	return 0;
 }

 static inline void unregister_fuseblk(void)
 {
 }
 #endif

 static decl_subsys(fuse, NULL, NULL);
 static decl_subsys(connections, NULL, NULL);

 static void fuse_inode_init_once(void *foo, struct kmem_cache *cachep,
 				 unsigned long flags)
 {
 	struct inode * inode = foo;

 	if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
 	    SLAB_CTOR_CONSTRUCTOR)
 		inode_init_once(inode);
 }

 static int __init fuse_fs_init(void)
 {
 	int err;

 	err = register_filesystem(&fuse_fs_type);
 	if (err)
 		goto out;

 	err = register_fuseblk();
 	if (err)
 		goto out_unreg;

 	fuse_inode_cachep = kmem_cache_create("fuse_inode",
 					      sizeof(struct fuse_inode),
 					      0, SLAB_HWCACHE_ALIGN,
 					      fuse_inode_init_once, NULL);
 	err = -ENOMEM;
 	if (!fuse_inode_cachep)
 		goto out_unreg2;

 	return 0;

  out_unreg2:
 	unregister_fuseblk();
  out_unreg:
 	unregister_filesystem(&fuse_fs_type);
  out:
 	return err;
 }

 static void fuse_fs_cleanup(void)
 {
 	unregister_filesystem(&fuse_fs_type);
 	unregister_fuseblk();
 	kmem_cache_destroy(fuse_inode_cachep);
 }

 static int fuse_sysfs_init(void)
 {
 	int err;

 	kset_set_kset_s(&fuse_subsys, fs_subsys);
 	err = subsystem_register(&fuse_subsys);
 	if (err)
 		goto out_err;

 	kset_set_kset_s(&connections_subsys, fuse_subsys);
 	err = subsystem_register(&connections_subsys);
 	if (err)
 		goto out_fuse_unregister;

 	return 0;

  out_fuse_unregister:
 	subsystem_unregister(&fuse_subsys);
  out_err:
 	return err;
 }

 static void fuse_sysfs_cleanup(void)
 {
 	subsystem_unregister(&connections_subsys);
 	subsystem_unregister(&fuse_subsys);
 }

 static int __init fuse_init(void)
 {
 	int res;

 	printk("fuse init (API version %i.%i)\n",
 	       FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);

 	INIT_LIST_HEAD(&fuse_conn_list);
 	res = fuse_fs_init();
 	if (res)
 		goto err;

 	res = fuse_dev_init();
 	if (res)
 		goto err_fs_cleanup;

 	res = fuse_sysfs_init();
 	if (res)
 		goto err_dev_cleanup;

 	res = fuse_ctl_init();
 	if (res)
 		goto err_sysfs_cleanup;

 	return 0;

  err_sysfs_cleanup:
 	fuse_sysfs_cleanup();
  err_dev_cleanup:
 	fuse_dev_cleanup();
  err_fs_cleanup:
 	fuse_fs_cleanup();
  err:
 	return res;
 }

 static void __exit fuse_exit(void)
 {
 	printk(KERN_DEBUG "fuse exit\n");

 	fuse_ctl_cleanup();
 	fuse_sysfs_cleanup();
 	fuse_fs_cleanup();
 	fuse_dev_cleanup();
 }

 module_init(fuse_init);
 module_exit(fuse_exit);
	/*
	FUSE: Filesystem in Userspace
	Copyright (C) 2001-2006 Miklos Szeredi <miklos@szeredi.hu>

	This program can be distributed under the terms of the GNU GPL.
	See the file COPYING.
	*/

	#include "fuse_i.h"

	#include <linux/pagemap.h>
	#include <linux/slab.h>
	#include <linux/file.h>
	#include <linux/seq_file.h>
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/parser.h>
	#include <linux/statfs.h>
	#include <linux/random.h>

	MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
	MODULE_DESCRIPTION("Filesystem in Userspace");
	MODULE_LICENSE("GPL");

	static struct kmem_cache *fuse_inode_cachep;
	struct list_head fuse_conn_list;
	DEFINE_MUTEX(fuse_mutex);

	#define FUSE_SUPER_MAGIC 0x65735546

	struct fuse_mount_data {
	int fd;
	unsigned rootmode;
	unsigned user_id;
	unsigned group_id;
	unsigned fd_present : 1;
	unsigned rootmode_present : 1;
	unsigned user_id_present : 1;
	unsigned group_id_present : 1;
	unsigned flags;
	unsigned max_read;
	unsigned blksize;
	};

	static struct inode fuse_alloc_inode(struct super_block sb)
	{
	struct inode *inode;
	struct fuse_inode *fi;

	inode = kmem_cache_alloc(fuse_inode_cachep, GFP_KERNEL);
	if (!inode)
	return NULL;

	fi = get_fuse_inode(inode);
	fi->i_time = 0;
	fi->nodeid = 0;
	fi->nlookup = 0;
	fi->forget_req = fuse_request_alloc();
	if (!fi->forget_req) {
	kmem_cache_free(fuse_inode_cachep, inode);
	return NULL;
	}

	return inode;
	}

	static void fuse_destroy_inode(struct inode *inode)
	{
	struct fuse_inode *fi = get_fuse_inode(inode);
	if (fi->forget_req)
	fuse_request_free(fi->forget_req);
	kmem_cache_free(fuse_inode_cachep, inode);
	}

	static void fuse_read_inode(struct inode *inode)
	{
	/* No op */
	}

	void fuse_send_forget(struct fuse_conn fc, struct fuse_req req,
	unsigned long nodeid, u64 nlookup)
	{
	struct fuse_forget_in *inarg = &req->misc.forget_in;
	inarg->nlookup = nlookup;
	req->in.h.opcode = FUSE_FORGET;
	req->in.h.nodeid = nodeid;
	req->in.numargs = 1;
	req->in.args[0].size = sizeof(struct fuse_forget_in);
	req->in.args[0].value = inarg;
	request_send_noreply(fc, req);
	}

	static void fuse_clear_inode(struct inode *inode)
	{
	if (inode->i_sb->s_flags & MS_ACTIVE) {
	struct fuse_conn *fc = get_fuse_conn(inode);
	struct fuse_inode *fi = get_fuse_inode(inode);
	fuse_send_forget(fc, fi->forget_req, fi->nodeid, fi->nlookup);
	fi->forget_req = NULL;
	}
	}

	static int fuse_remount_fs(struct super_block sb, int flags, char *data)
	{
	if (*flags & MS_MANDLOCK)
	return -EINVAL;

	return 0;
	}

	void fuse_change_attributes(struct inode inode, struct fuse_attr attr)
	{
	struct fuse_conn *fc = get_fuse_conn(inode);
	if (S_ISREG(inode->i_mode) && i_size_read(inode) != attr->size)
	invalidate_mapping_pages(inode->i_mapping, 0, -1);

	inode->i_ino = attr->ino;
	inode->i_mode = (inode->i_mode & S_IFMT) + (attr->mode & 07777);
	inode->i_nlink = attr->nlink;
	inode->i_uid = attr->uid;
	inode->i_gid = attr->gid;
	spin_lock(&fc->lock);
	i_size_write(inode, attr->size);
	spin_unlock(&fc->lock);
	inode->i_blocks = attr->blocks;
	inode->i_atime.tv_sec = attr->atime;
	inode->i_atime.tv_nsec = attr->atimensec;
	inode->i_mtime.tv_sec = attr->mtime;
	inode->i_mtime.tv_nsec = attr->mtimensec;
	inode->i_ctime.tv_sec = attr->ctime;
	inode->i_ctime.tv_nsec = attr->ctimensec;
	}

	static void fuse_init_inode(struct inode inode, struct fuse_attr attr)
	{
	inode->i_mode = attr->mode & S_IFMT;
	inode->i_size = attr->size;
	if (S_ISREG(inode->i_mode)) {
	fuse_init_common(inode);
	fuse_init_file_inode(inode);
	} else if (S_ISDIR(inode->i_mode))
	fuse_init_dir(inode);
	else if (S_ISLNK(inode->i_mode))
	fuse_init_symlink(inode);
	else if (S_ISCHR(inode->i_mode) \|\| S_ISBLK(inode->i_mode) \|\|
	S_ISFIFO(inode->i_mode) \|\| S_ISSOCK(inode->i_mode)) {
	fuse_init_common(inode);
	init_special_inode(inode, inode->i_mode,
	new_decode_dev(attr->rdev));
	} else
	BUG();
	}

	static int fuse_inode_eq(struct inode inode, void _nodeidp)
	{
	unsigned long nodeid = (unsigned long ) _nodeidp;
	if (get_node_id(inode) == nodeid)
	return 1;
	else
	return 0;
	}

	static int fuse_inode_set(struct inode inode, void _nodeidp)
	{
	unsigned long nodeid = (unsigned long ) _nodeidp;
	get_fuse_inode(inode)->nodeid = nodeid;
	return 0;
	}

	struct inode fuse_iget(struct super_block sb, unsigned long nodeid,
	int generation, struct fuse_attr *attr)
	{
	struct inode *inode;
	struct fuse_inode *fi;
	struct fuse_conn *fc = get_fuse_conn_super(sb);

	retry:
	inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);
	if (!inode)
	return NULL;

	if ((inode->i_state & I_NEW)) {
	inode->i_flags \|= S_NOATIME\|S_NOCMTIME;
	inode->i_generation = generation;
	inode->i_data.backing_dev_info = &fc->bdi;
	fuse_init_inode(inode, attr);
	unlock_new_inode(inode);
	} else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
	/* Inode has changed type, any I/O on the old should fail */
	make_bad_inode(inode);
	iput(inode);
	goto retry;
	}

	fi = get_fuse_inode(inode);
	spin_lock(&fc->lock);
	fi->nlookup ++;
	spin_unlock(&fc->lock);
	fuse_change_attributes(inode, attr);
	return inode;
	}

	static void fuse_umount_begin(struct vfsmount *vfsmnt, int flags)
	{
	if (flags & MNT_FORCE)
	fuse_abort_conn(get_fuse_conn_super(vfsmnt->mnt_sb));
	}

	static void fuse_send_destroy(struct fuse_conn *fc)
	{
	struct fuse_req *req = fc->destroy_req;
	if (req && fc->conn_init) {
	fc->destroy_req = NULL;
	req->in.h.opcode = FUSE_DESTROY;
	req->force = 1;
	request_send(fc, req);
	fuse_put_request(fc, req);
	}
	}

	static void fuse_put_super(struct super_block *sb)
	{
	struct fuse_conn *fc = get_fuse_conn_super(sb);

	fuse_send_destroy(fc);
	spin_lock(&fc->lock);
	fc->connected = 0;
	fc->blocked = 0;
	spin_unlock(&fc->lock);
	/* Flush all readers on this fs */
	kill_fasync(&fc->fasync, SIGIO, POLL_IN);
	wake_up_all(&fc->waitq);
	wake_up_all(&fc->blocked_waitq);
	mutex_lock(&fuse_mutex);
	list_del(&fc->entry);
	fuse_ctl_remove_conn(fc);
	mutex_unlock(&fuse_mutex);
	fuse_conn_put(fc);
	}

	static void convert_fuse_statfs(struct kstatfs stbuf, struct fuse_kstatfs attr)
	{
	stbuf->f_type = FUSE_SUPER_MAGIC;
	stbuf->f_bsize = attr->bsize;
	stbuf->f_frsize = attr->frsize;
	stbuf->f_blocks = attr->blocks;
	stbuf->f_bfree = attr->bfree;
	stbuf->f_bavail = attr->bavail;
	stbuf->f_files = attr->files;
	stbuf->f_ffree = attr->ffree;
	stbuf->f_namelen = attr->namelen;
	/* fsid is left zero */
	}

	static int fuse_statfs(struct dentry dentry, struct kstatfs buf)
	{
	struct super_block *sb = dentry->d_sb;
	struct fuse_conn *fc = get_fuse_conn_super(sb);
	struct fuse_req *req;
	struct fuse_statfs_out outarg;
	int err;

	req = fuse_get_req(fc);
	if (IS_ERR(req))
	return PTR_ERR(req);

	memset(&outarg, 0, sizeof(outarg));
	req->in.numargs = 0;
	req->in.h.opcode = FUSE_STATFS;
	req->in.h.nodeid = get_node_id(dentry->d_inode);
	req->out.numargs = 1;
	req->out.args[0].size =
	fc->minor < 4 ? FUSE_COMPAT_STATFS_SIZE : sizeof(outarg);
	req->out.args[0].value = &outarg;
	request_send(fc, req);
	err = req->out.h.error;
	if (!err)
	convert_fuse_statfs(buf, &outarg.st);
	fuse_put_request(fc, req);
	return err;
	}

	enum {
	OPT_FD,
	OPT_ROOTMODE,
	OPT_USER_ID,
	OPT_GROUP_ID,
	OPT_DEFAULT_PERMISSIONS,
	OPT_ALLOW_OTHER,
	OPT_MAX_READ,
	OPT_BLKSIZE,
	OPT_ERR
	};

	static match_table_t tokens = {
	{OPT_FD, "fd=%u"},
	{OPT_ROOTMODE, "rootmode=%o"},
	{OPT_USER_ID, "user_id=%u"},
	{OPT_GROUP_ID, "group_id=%u"},
	{OPT_DEFAULT_PERMISSIONS, "default_permissions"},
	{OPT_ALLOW_OTHER, "allow_other"},
	{OPT_MAX_READ, "max_read=%u"},
	{OPT_BLKSIZE, "blksize=%u"},
	{OPT_ERR, NULL}
	};

	static int parse_fuse_opt(char opt, struct fuse_mount_data d, int is_bdev)
	{
	char *p;
	memset(d, 0, sizeof(struct fuse_mount_data));
	d->max_read = ~0;
	d->blksize = 512;

	while ((p = strsep(&opt, ",")) != NULL) {
	int token;
	int value;
	substring_t args[MAX_OPT_ARGS];
	if (!*p)
	continue;

	token = match_token(p, tokens, args);
	switch (token) {
	case OPT_FD:
	if (match_int(&args[0], &value))
	return 0;
	d->fd = value;
	d->fd_present = 1;
	break;

	case OPT_ROOTMODE:
	if (match_octal(&args[0], &value))
	return 0;
	if (!fuse_valid_type(value))
	return 0;
	d->rootmode = value;
	d->rootmode_present = 1;
	break;

	case OPT_USER_ID:
	if (match_int(&args[0], &value))
	return 0;
	d->user_id = value;
	d->user_id_present = 1;
	break;

	case OPT_GROUP_ID:
	if (match_int(&args[0], &value))
	return 0;
	d->group_id = value;
	d->group_id_present = 1;
	break;

	case OPT_DEFAULT_PERMISSIONS:
	d->flags \|= FUSE_DEFAULT_PERMISSIONS;
	break;

	case OPT_ALLOW_OTHER:
	d->flags \|= FUSE_ALLOW_OTHER;
	break;

	case OPT_MAX_READ:
	if (match_int(&args[0], &value))
	return 0;
	d->max_read = value;
	break;

	case OPT_BLKSIZE:
	if (!is_bdev \|\| match_int(&args[0], &value))
	return 0;
	d->blksize = value;
	break;

	default:
	return 0;
	}
	}

	if (!d->fd_present \|\| !d->rootmode_present \|\|
	!d->user_id_present \|\| !d->group_id_present)
	return 0;

	return 1;
	}

	static int fuse_show_options(struct seq_file m, struct vfsmount mnt)
	{
	struct fuse_conn *fc = get_fuse_conn_super(mnt->mnt_sb);

	seq_printf(m, ",user_id=%u", fc->user_id);
	seq_printf(m, ",group_id=%u", fc->group_id);
	if (fc->flags & FUSE_DEFAULT_PERMISSIONS)
	seq_puts(m, ",default_permissions");
	if (fc->flags & FUSE_ALLOW_OTHER)
	seq_puts(m, ",allow_other");
	if (fc->max_read != ~0)
	seq_printf(m, ",max_read=%u", fc->max_read);
	return 0;
	}

	static struct fuse_conn *new_conn(void)
	{
	struct fuse_conn *fc;

	fc = kzalloc(sizeof(*fc), GFP_KERNEL);
	if (fc) {
	spin_lock_init(&fc->lock);
	mutex_init(&fc->inst_mutex);
	atomic_set(&fc->count, 1);
	init_waitqueue_head(&fc->waitq);
	init_waitqueue_head(&fc->blocked_waitq);
	INIT_LIST_HEAD(&fc->pending);
	INIT_LIST_HEAD(&fc->processing);
	INIT_LIST_HEAD(&fc->io);
	INIT_LIST_HEAD(&fc->interrupts);
	atomic_set(&fc->num_waiting, 0);
	fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
	fc->bdi.unplug_io_fn = default_unplug_io_fn;
	fc->reqctr = 0;
	fc->blocked = 1;
	get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));
	}
	return fc;
	}

	void fuse_conn_put(struct fuse_conn *fc)
	{
	if (atomic_dec_and_test(&fc->count)) {
	if (fc->destroy_req)
	fuse_request_free(fc->destroy_req);
	mutex_destroy(&fc->inst_mutex);
	kfree(fc);
	}
	}

	struct fuse_conn fuse_conn_get(struct fuse_conn fc)
	{
	atomic_inc(&fc->count);
	return fc;
	}

	static struct inode get_root_inode(struct super_block sb, unsigned mode)
	{
	struct fuse_attr attr;
	memset(&attr, 0, sizeof(attr));

	attr.mode = mode;
	attr.ino = FUSE_ROOT_ID;
	return fuse_iget(sb, 1, 0, &attr);
	}

	static const struct super_operations fuse_super_operations = {
	.alloc_inode = fuse_alloc_inode,
	.destroy_inode = fuse_destroy_inode,
	.read_inode = fuse_read_inode,
	.clear_inode = fuse_clear_inode,
	.remount_fs = fuse_remount_fs,
	.put_super = fuse_put_super,
	.umount_begin = fuse_umount_begin,
	.statfs = fuse_statfs,
	.show_options = fuse_show_options,
	};

	static void process_init_reply(struct fuse_conn fc, struct fuse_req req)
	{
	struct fuse_init_out *arg = &req->misc.init_out;

	if (req->out.h.error \|\| arg->major != FUSE_KERNEL_VERSION)
	fc->conn_error = 1;
	else {
	unsigned long ra_pages;

	if (arg->minor >= 6) {
	ra_pages = arg->max_readahead / PAGE_CACHE_SIZE;
	if (arg->flags & FUSE_ASYNC_READ)
	fc->async_read = 1;
	if (!(arg->flags & FUSE_POSIX_LOCKS))
	fc->no_lock = 1;
	} else {
	ra_pages = fc->max_read / PAGE_CACHE_SIZE;
	fc->no_lock = 1;
	}

	fc->bdi.ra_pages = min(fc->bdi.ra_pages, ra_pages);
	fc->minor = arg->minor;
	fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
	fc->conn_init = 1;
	}
	fuse_put_request(fc, req);
	fc->blocked = 0;
	wake_up_all(&fc->blocked_waitq);
	}

	static void fuse_send_init(struct fuse_conn fc, struct fuse_req req)
	{
	struct fuse_init_in *arg = &req->misc.init_in;

	arg->major = FUSE_KERNEL_VERSION;
	arg->minor = FUSE_KERNEL_MINOR_VERSION;
	arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
	arg->flags \|= FUSE_ASYNC_READ \| FUSE_POSIX_LOCKS;
	req->in.h.opcode = FUSE_INIT;
	req->in.numargs = 1;
	req->in.args[0].size = sizeof(*arg);
	req->in.args[0].value = arg;
	req->out.numargs = 1;
	/* Variable length arguement used for backward compatibility
	with interface version < 7.5. Rest of init_out is zeroed
	by do_get_request(), so a short reply is not a problem */
	req->out.argvar = 1;
	req->out.args[0].size = sizeof(struct fuse_init_out);
	req->out.args[0].value = &req->misc.init_out;
	req->end = process_init_reply;
	request_send_background(fc, req);
	}

	static u64 conn_id(void)
	{
	static u64 ctr = 1;
	return ctr++;
	}

	static int fuse_fill_super(struct super_block sb, void data, int silent)
	{
	struct fuse_conn *fc;
	struct inode *root;
	struct fuse_mount_data d;
	struct file *file;
	struct dentry *root_dentry;
	struct fuse_req *init_req;
	int err;
	int is_bdev = sb->s_bdev != NULL;

	if (sb->s_flags & MS_MANDLOCK)
	return -EINVAL;

	if (!parse_fuse_opt((char *) data, &d, is_bdev))
	return -EINVAL;

	if (is_bdev) {
	#ifdef CONFIG_BLOCK
	if (!sb_set_blocksize(sb, d.blksize))
	return -EINVAL;
	#endif
	} else {
	sb->s_blocksize = PAGE_CACHE_SIZE;
	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
	}
	sb->s_magic = FUSE_SUPER_MAGIC;
	sb->s_op = &fuse_super_operations;
	sb->s_maxbytes = MAX_LFS_FILESIZE;

	file = fget(d.fd);
	if (!file)
	return -EINVAL;

	if (file->f_op != &fuse_dev_operations)
	return -EINVAL;

	fc = new_conn();
	if (!fc)
	return -ENOMEM;

	fc->flags = d.flags;
	fc->user_id = d.user_id;
	fc->group_id = d.group_id;
	fc->max_read = d.max_read;

	/* Used by get_root_inode() */
	sb->s_fs_info = fc;

	err = -ENOMEM;
	root = get_root_inode(sb, d.rootmode);
	if (!root)
	goto err;

	root_dentry = d_alloc_root(root);
	if (!root_dentry) {
	iput(root);
	goto err;
	}

	init_req = fuse_request_alloc();
	if (!init_req)
	goto err_put_root;

	if (is_bdev) {
	fc->destroy_req = fuse_request_alloc();
	if (!fc->destroy_req)
	goto err_put_root;
	}

	mutex_lock(&fuse_mutex);
	err = -EINVAL;
	if (file->private_data)
	goto err_unlock;

	fc->id = conn_id();
	err = fuse_ctl_add_conn(fc);
	if (err)
	goto err_unlock;

	list_add_tail(&fc->entry, &fuse_conn_list);
	sb->s_root = root_dentry;
	fc->connected = 1;
	file->private_data = fuse_conn_get(fc);
	mutex_unlock(&fuse_mutex);
	/*
	* atomic_dec_and_test() in fput() provides the necessary
	* memory barrier for file->private_data to be visible on all
	* CPUs after this
	*/
	fput(file);

	fuse_send_init(fc, init_req);

	return 0;

	err_unlock:
	mutex_unlock(&fuse_mutex);
	fuse_request_free(init_req);
	err_put_root:
	dput(root_dentry);
	err:
	fput(file);
	fuse_conn_put(fc);
	return err;
	}

	static int fuse_get_sb(struct file_system_type *fs_type,
	int flags, const char *dev_name,
	void raw_data, struct vfsmount mnt)
	{
	return get_sb_nodev(fs_type, flags, raw_data, fuse_fill_super, mnt);
	}

	static struct file_system_type fuse_fs_type = {
	.owner = THIS_MODULE,
	.name = "fuse",
	.get_sb = fuse_get_sb,
	.kill_sb = kill_anon_super,
	};

	#ifdef CONFIG_BLOCK
	static int fuse_get_sb_blk(struct file_system_type *fs_type,
	int flags, const char *dev_name,
	void raw_data, struct vfsmount mnt)
	{
	return get_sb_bdev(fs_type, flags, dev_name, raw_data, fuse_fill_super,
	mnt);
	}

	static struct file_system_type fuseblk_fs_type = {
	.owner = THIS_MODULE,
	.name = "fuseblk",
	.get_sb = fuse_get_sb_blk,
	.kill_sb = kill_block_super,
	.fs_flags = FS_REQUIRES_DEV,
	};

	static inline int register_fuseblk(void)
	{
	return register_filesystem(&fuseblk_fs_type);
	}

	static inline void unregister_fuseblk(void)
	{
	unregister_filesystem(&fuseblk_fs_type);
	}
	#else
	static inline int register_fuseblk(void)
	{
	return 0;
	}

	static inline void unregister_fuseblk(void)
	{
	}
	#endif

	static decl_subsys(fuse, NULL, NULL);
	static decl_subsys(connections, NULL, NULL);

	static void fuse_inode_init_once(void foo, struct kmem_cache cachep,
	unsigned long flags)
	{
	struct inode * inode = foo;

	if ((flags & (SLAB_CTOR_VERIFY\|SLAB_CTOR_CONSTRUCTOR)) ==
	SLAB_CTOR_CONSTRUCTOR)
	inode_init_once(inode);
	}

	static int __init fuse_fs_init(void)
	{
	int err;

	err = register_filesystem(&fuse_fs_type);
	if (err)
	goto out;

	err = register_fuseblk();
	if (err)
	goto out_unreg;

	fuse_inode_cachep = kmem_cache_create("fuse_inode",
	sizeof(struct fuse_inode),
	0, SLAB_HWCACHE_ALIGN,
	fuse_inode_init_once, NULL);
	err = -ENOMEM;
	if (!fuse_inode_cachep)
	goto out_unreg2;

	return 0;

	out_unreg2:
	unregister_fuseblk();
	out_unreg:
	unregister_filesystem(&fuse_fs_type);
	out:
	return err;
	}

	static void fuse_fs_cleanup(void)
	{
	unregister_filesystem(&fuse_fs_type);
	unregister_fuseblk();
	kmem_cache_destroy(fuse_inode_cachep);
	}

	static int fuse_sysfs_init(void)
	{
	int err;

	kset_set_kset_s(&fuse_subsys, fs_subsys);
	err = subsystem_register(&fuse_subsys);
	if (err)
	goto out_err;

	kset_set_kset_s(&connections_subsys, fuse_subsys);
	err = subsystem_register(&connections_subsys);
	if (err)
	goto out_fuse_unregister;

	return 0;

	out_fuse_unregister:
	subsystem_unregister(&fuse_subsys);
	out_err:
	return err;
	}

	static void fuse_sysfs_cleanup(void)
	{
	subsystem_unregister(&connections_subsys);
	subsystem_unregister(&fuse_subsys);
	}

	static int __init fuse_init(void)
	{
	int res;

	printk("fuse init (API version %i.%i)\n",
	FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);

	INIT_LIST_HEAD(&fuse_conn_list);
	res = fuse_fs_init();
	if (res)
	goto err;

	res = fuse_dev_init();
	if (res)
	goto err_fs_cleanup;

	res = fuse_sysfs_init();
	if (res)
	goto err_dev_cleanup;

	res = fuse_ctl_init();
	if (res)
	goto err_sysfs_cleanup;

	return 0;

	err_sysfs_cleanup:
	fuse_sysfs_cleanup();
	err_dev_cleanup:
	fuse_dev_cleanup();
	err_fs_cleanup:
	fuse_fs_cleanup();
	err:
	return res;
	}

	static void __exit fuse_exit(void)
	{
	printk(KERN_DEBUG "fuse exit\n");

	fuse_ctl_cleanup();
	fuse_sysfs_cleanup();
	fuse_fs_cleanup();
	fuse_dev_cleanup();
	}

	module_init(fuse_init);
	module_exit(fuse_exit);