xref: /openbmc/linux/fs/fuse/inode.c (revision a1e58bbd)
1 /*
2   FUSE: Filesystem in Userspace
3   Copyright (C) 2001-2006  Miklos Szeredi <miklos@szeredi.hu>
4 
5   This program can be distributed under the terms of the GNU GPL.
6   See the file COPYING.
7 */
8 
9 #include "fuse_i.h"
10 
11 #include <linux/pagemap.h>
12 #include <linux/slab.h>
13 #include <linux/file.h>
14 #include <linux/seq_file.h>
15 #include <linux/init.h>
16 #include <linux/module.h>
17 #include <linux/parser.h>
18 #include <linux/statfs.h>
19 #include <linux/random.h>
20 #include <linux/sched.h>
21 
22 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
23 MODULE_DESCRIPTION("Filesystem in Userspace");
24 MODULE_LICENSE("GPL");
25 
26 static struct kmem_cache *fuse_inode_cachep;
27 struct list_head fuse_conn_list;
28 DEFINE_MUTEX(fuse_mutex);
29 
30 #define FUSE_SUPER_MAGIC 0x65735546
31 
32 #define FUSE_DEFAULT_BLKSIZE 512
33 
34 struct fuse_mount_data {
35 	int fd;
36 	unsigned rootmode;
37 	unsigned user_id;
38 	unsigned group_id;
39 	unsigned fd_present : 1;
40 	unsigned rootmode_present : 1;
41 	unsigned user_id_present : 1;
42 	unsigned group_id_present : 1;
43 	unsigned flags;
44 	unsigned max_read;
45 	unsigned blksize;
46 };
47 
48 static struct inode *fuse_alloc_inode(struct super_block *sb)
49 {
50 	struct inode *inode;
51 	struct fuse_inode *fi;
52 
53 	inode = kmem_cache_alloc(fuse_inode_cachep, GFP_KERNEL);
54 	if (!inode)
55 		return NULL;
56 
57 	fi = get_fuse_inode(inode);
58 	fi->i_time = 0;
59 	fi->nodeid = 0;
60 	fi->nlookup = 0;
61 	fi->attr_version = 0;
62 	INIT_LIST_HEAD(&fi->write_files);
63 	fi->forget_req = fuse_request_alloc();
64 	if (!fi->forget_req) {
65 		kmem_cache_free(fuse_inode_cachep, inode);
66 		return NULL;
67 	}
68 
69 	return inode;
70 }
71 
72 static void fuse_destroy_inode(struct inode *inode)
73 {
74 	struct fuse_inode *fi = get_fuse_inode(inode);
75 	BUG_ON(!list_empty(&fi->write_files));
76 	if (fi->forget_req)
77 		fuse_request_free(fi->forget_req);
78 	kmem_cache_free(fuse_inode_cachep, inode);
79 }
80 
81 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
82 		      unsigned long nodeid, u64 nlookup)
83 {
84 	struct fuse_forget_in *inarg = &req->misc.forget_in;
85 	inarg->nlookup = nlookup;
86 	req->in.h.opcode = FUSE_FORGET;
87 	req->in.h.nodeid = nodeid;
88 	req->in.numargs = 1;
89 	req->in.args[0].size = sizeof(struct fuse_forget_in);
90 	req->in.args[0].value = inarg;
91 	request_send_noreply(fc, req);
92 }
93 
94 static void fuse_clear_inode(struct inode *inode)
95 {
96 	if (inode->i_sb->s_flags & MS_ACTIVE) {
97 		struct fuse_conn *fc = get_fuse_conn(inode);
98 		struct fuse_inode *fi = get_fuse_inode(inode);
99 		fuse_send_forget(fc, fi->forget_req, fi->nodeid, fi->nlookup);
100 		fi->forget_req = NULL;
101 	}
102 }
103 
104 static int fuse_remount_fs(struct super_block *sb, int *flags, char *data)
105 {
106 	if (*flags & MS_MANDLOCK)
107 		return -EINVAL;
108 
109 	return 0;
110 }
111 
112 static void fuse_truncate(struct address_space *mapping, loff_t offset)
113 {
114 	/* See vmtruncate() */
115 	unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
116 	truncate_inode_pages(mapping, offset);
117 	unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
118 }
119 
120 
121 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
122 			    u64 attr_valid, u64 attr_version)
123 {
124 	struct fuse_conn *fc = get_fuse_conn(inode);
125 	struct fuse_inode *fi = get_fuse_inode(inode);
126 	loff_t oldsize;
127 
128 	spin_lock(&fc->lock);
129 	if (attr_version != 0 && fi->attr_version > attr_version) {
130 		spin_unlock(&fc->lock);
131 		return;
132 	}
133 	fi->attr_version = ++fc->attr_version;
134 	fi->i_time = attr_valid;
135 
136 	inode->i_ino     = attr->ino;
137 	inode->i_mode    = (inode->i_mode & S_IFMT) | (attr->mode & 07777);
138 	inode->i_nlink   = attr->nlink;
139 	inode->i_uid     = attr->uid;
140 	inode->i_gid     = attr->gid;
141 	inode->i_blocks  = attr->blocks;
142 	inode->i_atime.tv_sec   = attr->atime;
143 	inode->i_atime.tv_nsec  = attr->atimensec;
144 	inode->i_mtime.tv_sec   = attr->mtime;
145 	inode->i_mtime.tv_nsec  = attr->mtimensec;
146 	inode->i_ctime.tv_sec   = attr->ctime;
147 	inode->i_ctime.tv_nsec  = attr->ctimensec;
148 
149 	if (attr->blksize != 0)
150 		inode->i_blkbits = ilog2(attr->blksize);
151 	else
152 		inode->i_blkbits = inode->i_sb->s_blocksize_bits;
153 
154 	/*
155 	 * Don't set the sticky bit in i_mode, unless we want the VFS
156 	 * to check permissions.  This prevents failures due to the
157 	 * check in may_delete().
158 	 */
159 	fi->orig_i_mode = inode->i_mode;
160 	if (!(fc->flags & FUSE_DEFAULT_PERMISSIONS))
161 		inode->i_mode &= ~S_ISVTX;
162 
163 	oldsize = inode->i_size;
164 	i_size_write(inode, attr->size);
165 	spin_unlock(&fc->lock);
166 
167 	if (S_ISREG(inode->i_mode) && oldsize != attr->size) {
168 		if (attr->size < oldsize)
169 			fuse_truncate(inode->i_mapping, attr->size);
170 		invalidate_inode_pages2(inode->i_mapping);
171 	}
172 }
173 
174 static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
175 {
176 	inode->i_mode = attr->mode & S_IFMT;
177 	inode->i_size = attr->size;
178 	if (S_ISREG(inode->i_mode)) {
179 		fuse_init_common(inode);
180 		fuse_init_file_inode(inode);
181 	} else if (S_ISDIR(inode->i_mode))
182 		fuse_init_dir(inode);
183 	else if (S_ISLNK(inode->i_mode))
184 		fuse_init_symlink(inode);
185 	else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
186 		 S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
187 		fuse_init_common(inode);
188 		init_special_inode(inode, inode->i_mode,
189 				   new_decode_dev(attr->rdev));
190 	} else
191 		BUG();
192 }
193 
194 static int fuse_inode_eq(struct inode *inode, void *_nodeidp)
195 {
196 	unsigned long nodeid = *(unsigned long *) _nodeidp;
197 	if (get_node_id(inode) == nodeid)
198 		return 1;
199 	else
200 		return 0;
201 }
202 
203 static int fuse_inode_set(struct inode *inode, void *_nodeidp)
204 {
205 	unsigned long nodeid = *(unsigned long *) _nodeidp;
206 	get_fuse_inode(inode)->nodeid = nodeid;
207 	return 0;
208 }
209 
210 struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
211 			int generation, struct fuse_attr *attr,
212 			u64 attr_valid, u64 attr_version)
213 {
214 	struct inode *inode;
215 	struct fuse_inode *fi;
216 	struct fuse_conn *fc = get_fuse_conn_super(sb);
217 
218  retry:
219 	inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);
220 	if (!inode)
221 		return NULL;
222 
223 	if ((inode->i_state & I_NEW)) {
224 		inode->i_flags |= S_NOATIME|S_NOCMTIME;
225 		inode->i_generation = generation;
226 		inode->i_data.backing_dev_info = &fc->bdi;
227 		fuse_init_inode(inode, attr);
228 		unlock_new_inode(inode);
229 	} else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
230 		/* Inode has changed type, any I/O on the old should fail */
231 		make_bad_inode(inode);
232 		iput(inode);
233 		goto retry;
234 	}
235 
236 	fi = get_fuse_inode(inode);
237 	spin_lock(&fc->lock);
238 	fi->nlookup ++;
239 	spin_unlock(&fc->lock);
240 	fuse_change_attributes(inode, attr, attr_valid, attr_version);
241 
242 	return inode;
243 }
244 
245 static void fuse_umount_begin(struct vfsmount *vfsmnt, int flags)
246 {
247 	if (flags & MNT_FORCE)
248 		fuse_abort_conn(get_fuse_conn_super(vfsmnt->mnt_sb));
249 }
250 
251 static void fuse_send_destroy(struct fuse_conn *fc)
252 {
253 	struct fuse_req *req = fc->destroy_req;
254 	if (req && fc->conn_init) {
255 		fc->destroy_req = NULL;
256 		req->in.h.opcode = FUSE_DESTROY;
257 		req->force = 1;
258 		request_send(fc, req);
259 		fuse_put_request(fc, req);
260 	}
261 }
262 
263 static void fuse_put_super(struct super_block *sb)
264 {
265 	struct fuse_conn *fc = get_fuse_conn_super(sb);
266 
267 	fuse_send_destroy(fc);
268 	spin_lock(&fc->lock);
269 	fc->connected = 0;
270 	fc->blocked = 0;
271 	spin_unlock(&fc->lock);
272 	/* Flush all readers on this fs */
273 	kill_fasync(&fc->fasync, SIGIO, POLL_IN);
274 	wake_up_all(&fc->waitq);
275 	wake_up_all(&fc->blocked_waitq);
276 	wake_up_all(&fc->reserved_req_waitq);
277 	mutex_lock(&fuse_mutex);
278 	list_del(&fc->entry);
279 	fuse_ctl_remove_conn(fc);
280 	mutex_unlock(&fuse_mutex);
281 	fuse_conn_put(fc);
282 }
283 
284 static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
285 {
286 	stbuf->f_type    = FUSE_SUPER_MAGIC;
287 	stbuf->f_bsize   = attr->bsize;
288 	stbuf->f_frsize  = attr->frsize;
289 	stbuf->f_blocks  = attr->blocks;
290 	stbuf->f_bfree   = attr->bfree;
291 	stbuf->f_bavail  = attr->bavail;
292 	stbuf->f_files   = attr->files;
293 	stbuf->f_ffree   = attr->ffree;
294 	stbuf->f_namelen = attr->namelen;
295 	/* fsid is left zero */
296 }
297 
298 static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)
299 {
300 	struct super_block *sb = dentry->d_sb;
301 	struct fuse_conn *fc = get_fuse_conn_super(sb);
302 	struct fuse_req *req;
303 	struct fuse_statfs_out outarg;
304 	int err;
305 
306 	if (!fuse_allow_task(fc, current)) {
307 		buf->f_type = FUSE_SUPER_MAGIC;
308 		return 0;
309 	}
310 
311 	req = fuse_get_req(fc);
312 	if (IS_ERR(req))
313 		return PTR_ERR(req);
314 
315 	memset(&outarg, 0, sizeof(outarg));
316 	req->in.numargs = 0;
317 	req->in.h.opcode = FUSE_STATFS;
318 	req->in.h.nodeid = get_node_id(dentry->d_inode);
319 	req->out.numargs = 1;
320 	req->out.args[0].size =
321 		fc->minor < 4 ? FUSE_COMPAT_STATFS_SIZE : sizeof(outarg);
322 	req->out.args[0].value = &outarg;
323 	request_send(fc, req);
324 	err = req->out.h.error;
325 	if (!err)
326 		convert_fuse_statfs(buf, &outarg.st);
327 	fuse_put_request(fc, req);
328 	return err;
329 }
330 
331 enum {
332 	OPT_FD,
333 	OPT_ROOTMODE,
334 	OPT_USER_ID,
335 	OPT_GROUP_ID,
336 	OPT_DEFAULT_PERMISSIONS,
337 	OPT_ALLOW_OTHER,
338 	OPT_MAX_READ,
339 	OPT_BLKSIZE,
340 	OPT_ERR
341 };
342 
343 static match_table_t tokens = {
344 	{OPT_FD,			"fd=%u"},
345 	{OPT_ROOTMODE,			"rootmode=%o"},
346 	{OPT_USER_ID,			"user_id=%u"},
347 	{OPT_GROUP_ID,			"group_id=%u"},
348 	{OPT_DEFAULT_PERMISSIONS,	"default_permissions"},
349 	{OPT_ALLOW_OTHER,		"allow_other"},
350 	{OPT_MAX_READ,			"max_read=%u"},
351 	{OPT_BLKSIZE,			"blksize=%u"},
352 	{OPT_ERR,			NULL}
353 };
354 
355 static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev)
356 {
357 	char *p;
358 	memset(d, 0, sizeof(struct fuse_mount_data));
359 	d->max_read = ~0;
360 	d->blksize = FUSE_DEFAULT_BLKSIZE;
361 
362 	while ((p = strsep(&opt, ",")) != NULL) {
363 		int token;
364 		int value;
365 		substring_t args[MAX_OPT_ARGS];
366 		if (!*p)
367 			continue;
368 
369 		token = match_token(p, tokens, args);
370 		switch (token) {
371 		case OPT_FD:
372 			if (match_int(&args[0], &value))
373 				return 0;
374 			d->fd = value;
375 			d->fd_present = 1;
376 			break;
377 
378 		case OPT_ROOTMODE:
379 			if (match_octal(&args[0], &value))
380 				return 0;
381 			if (!fuse_valid_type(value))
382 				return 0;
383 			d->rootmode = value;
384 			d->rootmode_present = 1;
385 			break;
386 
387 		case OPT_USER_ID:
388 			if (match_int(&args[0], &value))
389 				return 0;
390 			d->user_id = value;
391 			d->user_id_present = 1;
392 			break;
393 
394 		case OPT_GROUP_ID:
395 			if (match_int(&args[0], &value))
396 				return 0;
397 			d->group_id = value;
398 			d->group_id_present = 1;
399 			break;
400 
401 		case OPT_DEFAULT_PERMISSIONS:
402 			d->flags |= FUSE_DEFAULT_PERMISSIONS;
403 			break;
404 
405 		case OPT_ALLOW_OTHER:
406 			d->flags |= FUSE_ALLOW_OTHER;
407 			break;
408 
409 		case OPT_MAX_READ:
410 			if (match_int(&args[0], &value))
411 				return 0;
412 			d->max_read = value;
413 			break;
414 
415 		case OPT_BLKSIZE:
416 			if (!is_bdev || match_int(&args[0], &value))
417 				return 0;
418 			d->blksize = value;
419 			break;
420 
421 		default:
422 			return 0;
423 		}
424 	}
425 
426 	if (!d->fd_present || !d->rootmode_present ||
427 	    !d->user_id_present || !d->group_id_present)
428 		return 0;
429 
430 	return 1;
431 }
432 
433 static int fuse_show_options(struct seq_file *m, struct vfsmount *mnt)
434 {
435 	struct fuse_conn *fc = get_fuse_conn_super(mnt->mnt_sb);
436 
437 	seq_printf(m, ",user_id=%u", fc->user_id);
438 	seq_printf(m, ",group_id=%u", fc->group_id);
439 	if (fc->flags & FUSE_DEFAULT_PERMISSIONS)
440 		seq_puts(m, ",default_permissions");
441 	if (fc->flags & FUSE_ALLOW_OTHER)
442 		seq_puts(m, ",allow_other");
443 	if (fc->max_read != ~0)
444 		seq_printf(m, ",max_read=%u", fc->max_read);
445 	if (mnt->mnt_sb->s_bdev &&
446 	    mnt->mnt_sb->s_blocksize != FUSE_DEFAULT_BLKSIZE)
447 		seq_printf(m, ",blksize=%lu", mnt->mnt_sb->s_blocksize);
448 	return 0;
449 }
450 
451 static struct fuse_conn *new_conn(void)
452 {
453 	struct fuse_conn *fc;
454 	int err;
455 
456 	fc = kzalloc(sizeof(*fc), GFP_KERNEL);
457 	if (fc) {
458 		spin_lock_init(&fc->lock);
459 		mutex_init(&fc->inst_mutex);
460 		atomic_set(&fc->count, 1);
461 		init_waitqueue_head(&fc->waitq);
462 		init_waitqueue_head(&fc->blocked_waitq);
463 		init_waitqueue_head(&fc->reserved_req_waitq);
464 		INIT_LIST_HEAD(&fc->pending);
465 		INIT_LIST_HEAD(&fc->processing);
466 		INIT_LIST_HEAD(&fc->io);
467 		INIT_LIST_HEAD(&fc->interrupts);
468 		INIT_LIST_HEAD(&fc->bg_queue);
469 		atomic_set(&fc->num_waiting, 0);
470 		fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
471 		fc->bdi.unplug_io_fn = default_unplug_io_fn;
472 		err = bdi_init(&fc->bdi);
473 		if (err) {
474 			kfree(fc);
475 			fc = NULL;
476 			goto out;
477 		}
478 		fc->reqctr = 0;
479 		fc->blocked = 1;
480 		fc->attr_version = 1;
481 		get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));
482 	}
483 out:
484 	return fc;
485 }
486 
487 void fuse_conn_put(struct fuse_conn *fc)
488 {
489 	if (atomic_dec_and_test(&fc->count)) {
490 		if (fc->destroy_req)
491 			fuse_request_free(fc->destroy_req);
492 		mutex_destroy(&fc->inst_mutex);
493 		bdi_destroy(&fc->bdi);
494 		kfree(fc);
495 	}
496 }
497 
498 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc)
499 {
500 	atomic_inc(&fc->count);
501 	return fc;
502 }
503 
504 static struct inode *get_root_inode(struct super_block *sb, unsigned mode)
505 {
506 	struct fuse_attr attr;
507 	memset(&attr, 0, sizeof(attr));
508 
509 	attr.mode = mode;
510 	attr.ino = FUSE_ROOT_ID;
511 	attr.nlink = 1;
512 	return fuse_iget(sb, 1, 0, &attr, 0, 0);
513 }
514 
515 static const struct super_operations fuse_super_operations = {
516 	.alloc_inode    = fuse_alloc_inode,
517 	.destroy_inode  = fuse_destroy_inode,
518 	.clear_inode	= fuse_clear_inode,
519 	.drop_inode	= generic_delete_inode,
520 	.remount_fs	= fuse_remount_fs,
521 	.put_super	= fuse_put_super,
522 	.umount_begin	= fuse_umount_begin,
523 	.statfs		= fuse_statfs,
524 	.show_options	= fuse_show_options,
525 };
526 
527 static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
528 {
529 	struct fuse_init_out *arg = &req->misc.init_out;
530 
531 	if (req->out.h.error || arg->major != FUSE_KERNEL_VERSION)
532 		fc->conn_error = 1;
533 	else {
534 		unsigned long ra_pages;
535 
536 		if (arg->minor >= 6) {
537 			ra_pages = arg->max_readahead / PAGE_CACHE_SIZE;
538 			if (arg->flags & FUSE_ASYNC_READ)
539 				fc->async_read = 1;
540 			if (!(arg->flags & FUSE_POSIX_LOCKS))
541 				fc->no_lock = 1;
542 			if (arg->flags & FUSE_ATOMIC_O_TRUNC)
543 				fc->atomic_o_trunc = 1;
544 		} else {
545 			ra_pages = fc->max_read / PAGE_CACHE_SIZE;
546 			fc->no_lock = 1;
547 		}
548 
549 		fc->bdi.ra_pages = min(fc->bdi.ra_pages, ra_pages);
550 		fc->minor = arg->minor;
551 		fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
552 		fc->conn_init = 1;
553 	}
554 	fuse_put_request(fc, req);
555 	fc->blocked = 0;
556 	wake_up_all(&fc->blocked_waitq);
557 }
558 
559 static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
560 {
561 	struct fuse_init_in *arg = &req->misc.init_in;
562 
563 	arg->major = FUSE_KERNEL_VERSION;
564 	arg->minor = FUSE_KERNEL_MINOR_VERSION;
565 	arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
566 	arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC;
567 	req->in.h.opcode = FUSE_INIT;
568 	req->in.numargs = 1;
569 	req->in.args[0].size = sizeof(*arg);
570 	req->in.args[0].value = arg;
571 	req->out.numargs = 1;
572 	/* Variable length arguement used for backward compatibility
573 	   with interface version < 7.5.  Rest of init_out is zeroed
574 	   by do_get_request(), so a short reply is not a problem */
575 	req->out.argvar = 1;
576 	req->out.args[0].size = sizeof(struct fuse_init_out);
577 	req->out.args[0].value = &req->misc.init_out;
578 	req->end = process_init_reply;
579 	request_send_background(fc, req);
580 }
581 
582 static u64 conn_id(void)
583 {
584 	static u64 ctr = 1;
585 	return ctr++;
586 }
587 
588 static int fuse_fill_super(struct super_block *sb, void *data, int silent)
589 {
590 	struct fuse_conn *fc;
591 	struct inode *root;
592 	struct fuse_mount_data d;
593 	struct file *file;
594 	struct dentry *root_dentry;
595 	struct fuse_req *init_req;
596 	int err;
597 	int is_bdev = sb->s_bdev != NULL;
598 
599 	if (sb->s_flags & MS_MANDLOCK)
600 		return -EINVAL;
601 
602 	if (!parse_fuse_opt((char *) data, &d, is_bdev))
603 		return -EINVAL;
604 
605 	if (is_bdev) {
606 #ifdef CONFIG_BLOCK
607 		if (!sb_set_blocksize(sb, d.blksize))
608 			return -EINVAL;
609 #endif
610 	} else {
611 		sb->s_blocksize = PAGE_CACHE_SIZE;
612 		sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
613 	}
614 	sb->s_magic = FUSE_SUPER_MAGIC;
615 	sb->s_op = &fuse_super_operations;
616 	sb->s_maxbytes = MAX_LFS_FILESIZE;
617 
618 	file = fget(d.fd);
619 	if (!file)
620 		return -EINVAL;
621 
622 	if (file->f_op != &fuse_dev_operations)
623 		return -EINVAL;
624 
625 	fc = new_conn();
626 	if (!fc)
627 		return -ENOMEM;
628 
629 	fc->flags = d.flags;
630 	fc->user_id = d.user_id;
631 	fc->group_id = d.group_id;
632 	fc->max_read = d.max_read;
633 
634 	/* Used by get_root_inode() */
635 	sb->s_fs_info = fc;
636 
637 	err = -ENOMEM;
638 	root = get_root_inode(sb, d.rootmode);
639 	if (!root)
640 		goto err;
641 
642 	root_dentry = d_alloc_root(root);
643 	if (!root_dentry) {
644 		iput(root);
645 		goto err;
646 	}
647 
648 	init_req = fuse_request_alloc();
649 	if (!init_req)
650 		goto err_put_root;
651 
652 	if (is_bdev) {
653 		fc->destroy_req = fuse_request_alloc();
654 		if (!fc->destroy_req)
655 			goto err_put_root;
656 	}
657 
658 	mutex_lock(&fuse_mutex);
659 	err = -EINVAL;
660 	if (file->private_data)
661 		goto err_unlock;
662 
663 	fc->id = conn_id();
664 	err = fuse_ctl_add_conn(fc);
665 	if (err)
666 		goto err_unlock;
667 
668 	list_add_tail(&fc->entry, &fuse_conn_list);
669 	sb->s_root = root_dentry;
670 	fc->connected = 1;
671 	file->private_data = fuse_conn_get(fc);
672 	mutex_unlock(&fuse_mutex);
673 	/*
674 	 * atomic_dec_and_test() in fput() provides the necessary
675 	 * memory barrier for file->private_data to be visible on all
676 	 * CPUs after this
677 	 */
678 	fput(file);
679 
680 	fuse_send_init(fc, init_req);
681 
682 	return 0;
683 
684  err_unlock:
685 	mutex_unlock(&fuse_mutex);
686 	fuse_request_free(init_req);
687  err_put_root:
688 	dput(root_dentry);
689  err:
690 	fput(file);
691 	fuse_conn_put(fc);
692 	return err;
693 }
694 
695 static int fuse_get_sb(struct file_system_type *fs_type,
696 		       int flags, const char *dev_name,
697 		       void *raw_data, struct vfsmount *mnt)
698 {
699 	return get_sb_nodev(fs_type, flags, raw_data, fuse_fill_super, mnt);
700 }
701 
702 static struct file_system_type fuse_fs_type = {
703 	.owner		= THIS_MODULE,
704 	.name		= "fuse",
705 	.fs_flags	= FS_HAS_SUBTYPE,
706 	.get_sb		= fuse_get_sb,
707 	.kill_sb	= kill_anon_super,
708 };
709 
710 #ifdef CONFIG_BLOCK
711 static int fuse_get_sb_blk(struct file_system_type *fs_type,
712 			   int flags, const char *dev_name,
713 			   void *raw_data, struct vfsmount *mnt)
714 {
715 	return get_sb_bdev(fs_type, flags, dev_name, raw_data, fuse_fill_super,
716 			   mnt);
717 }
718 
719 static struct file_system_type fuseblk_fs_type = {
720 	.owner		= THIS_MODULE,
721 	.name		= "fuseblk",
722 	.get_sb		= fuse_get_sb_blk,
723 	.kill_sb	= kill_block_super,
724 	.fs_flags	= FS_REQUIRES_DEV | FS_HAS_SUBTYPE,
725 };
726 
727 static inline int register_fuseblk(void)
728 {
729 	return register_filesystem(&fuseblk_fs_type);
730 }
731 
732 static inline void unregister_fuseblk(void)
733 {
734 	unregister_filesystem(&fuseblk_fs_type);
735 }
736 #else
737 static inline int register_fuseblk(void)
738 {
739 	return 0;
740 }
741 
742 static inline void unregister_fuseblk(void)
743 {
744 }
745 #endif
746 
747 static void fuse_inode_init_once(struct kmem_cache *cachep, void *foo)
748 {
749 	struct inode * inode = foo;
750 
751 	inode_init_once(inode);
752 }
753 
754 static int __init fuse_fs_init(void)
755 {
756 	int err;
757 
758 	err = register_filesystem(&fuse_fs_type);
759 	if (err)
760 		goto out;
761 
762 	err = register_fuseblk();
763 	if (err)
764 		goto out_unreg;
765 
766 	fuse_inode_cachep = kmem_cache_create("fuse_inode",
767 					      sizeof(struct fuse_inode),
768 					      0, SLAB_HWCACHE_ALIGN,
769 					      fuse_inode_init_once);
770 	err = -ENOMEM;
771 	if (!fuse_inode_cachep)
772 		goto out_unreg2;
773 
774 	return 0;
775 
776  out_unreg2:
777 	unregister_fuseblk();
778  out_unreg:
779 	unregister_filesystem(&fuse_fs_type);
780  out:
781 	return err;
782 }
783 
784 static void fuse_fs_cleanup(void)
785 {
786 	unregister_filesystem(&fuse_fs_type);
787 	unregister_fuseblk();
788 	kmem_cache_destroy(fuse_inode_cachep);
789 }
790 
791 static struct kobject *fuse_kobj;
792 static struct kobject *connections_kobj;
793 
794 static int fuse_sysfs_init(void)
795 {
796 	int err;
797 
798 	fuse_kobj = kobject_create_and_add("fuse", fs_kobj);
799 	if (!fuse_kobj) {
800 		err = -ENOMEM;
801 		goto out_err;
802 	}
803 
804 	connections_kobj = kobject_create_and_add("connections", fuse_kobj);
805 	if (!connections_kobj) {
806 		err = -ENOMEM;
807 		goto out_fuse_unregister;
808 	}
809 
810 	return 0;
811 
812  out_fuse_unregister:
813 	kobject_put(fuse_kobj);
814  out_err:
815 	return err;
816 }
817 
818 static void fuse_sysfs_cleanup(void)
819 {
820 	kobject_put(connections_kobj);
821 	kobject_put(fuse_kobj);
822 }
823 
824 static int __init fuse_init(void)
825 {
826 	int res;
827 
828 	printk("fuse init (API version %i.%i)\n",
829 	       FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
830 
831 	INIT_LIST_HEAD(&fuse_conn_list);
832 	res = fuse_fs_init();
833 	if (res)
834 		goto err;
835 
836 	res = fuse_dev_init();
837 	if (res)
838 		goto err_fs_cleanup;
839 
840 	res = fuse_sysfs_init();
841 	if (res)
842 		goto err_dev_cleanup;
843 
844 	res = fuse_ctl_init();
845 	if (res)
846 		goto err_sysfs_cleanup;
847 
848 	return 0;
849 
850  err_sysfs_cleanup:
851 	fuse_sysfs_cleanup();
852  err_dev_cleanup:
853 	fuse_dev_cleanup();
854  err_fs_cleanup:
855 	fuse_fs_cleanup();
856  err:
857 	return res;
858 }
859 
860 static void __exit fuse_exit(void)
861 {
862 	printk(KERN_DEBUG "fuse exit\n");
863 
864 	fuse_ctl_cleanup();
865 	fuse_sysfs_cleanup();
866 	fuse_fs_cleanup();
867 	fuse_dev_cleanup();
868 }
869 
870 module_init(fuse_init);
871 module_exit(fuse_exit);
872