xref: /linux/fs/fuse/inode.c (revision 98366c20a275e957416e9516db5dcb7195b4e101)
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 struct fuse_mount_data {
33 	int fd;
34 	unsigned rootmode;
35 	unsigned user_id;
36 	unsigned group_id;
37 	unsigned fd_present : 1;
38 	unsigned rootmode_present : 1;
39 	unsigned user_id_present : 1;
40 	unsigned group_id_present : 1;
41 	unsigned flags;
42 	unsigned max_read;
43 	unsigned blksize;
44 };
45 
46 static struct inode *fuse_alloc_inode(struct super_block *sb)
47 {
48 	struct inode *inode;
49 	struct fuse_inode *fi;
50 
51 	inode = kmem_cache_alloc(fuse_inode_cachep, GFP_KERNEL);
52 	if (!inode)
53 		return NULL;
54 
55 	fi = get_fuse_inode(inode);
56 	fi->i_time = 0;
57 	fi->nodeid = 0;
58 	fi->nlookup = 0;
59 	INIT_LIST_HEAD(&fi->write_files);
60 	fi->forget_req = fuse_request_alloc();
61 	if (!fi->forget_req) {
62 		kmem_cache_free(fuse_inode_cachep, inode);
63 		return NULL;
64 	}
65 
66 	return inode;
67 }
68 
69 static void fuse_destroy_inode(struct inode *inode)
70 {
71 	struct fuse_inode *fi = get_fuse_inode(inode);
72 	BUG_ON(!list_empty(&fi->write_files));
73 	if (fi->forget_req)
74 		fuse_request_free(fi->forget_req);
75 	kmem_cache_free(fuse_inode_cachep, inode);
76 }
77 
78 static void fuse_read_inode(struct inode *inode)
79 {
80 	/* No op */
81 }
82 
83 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
84 		      unsigned long nodeid, u64 nlookup)
85 {
86 	struct fuse_forget_in *inarg = &req->misc.forget_in;
87 	inarg->nlookup = nlookup;
88 	req->in.h.opcode = FUSE_FORGET;
89 	req->in.h.nodeid = nodeid;
90 	req->in.numargs = 1;
91 	req->in.args[0].size = sizeof(struct fuse_forget_in);
92 	req->in.args[0].value = inarg;
93 	request_send_noreply(fc, req);
94 }
95 
96 static void fuse_clear_inode(struct inode *inode)
97 {
98 	if (inode->i_sb->s_flags & MS_ACTIVE) {
99 		struct fuse_conn *fc = get_fuse_conn(inode);
100 		struct fuse_inode *fi = get_fuse_inode(inode);
101 		fuse_send_forget(fc, fi->forget_req, fi->nodeid, fi->nlookup);
102 		fi->forget_req = NULL;
103 	}
104 }
105 
106 static int fuse_remount_fs(struct super_block *sb, int *flags, char *data)
107 {
108 	if (*flags & MS_MANDLOCK)
109 		return -EINVAL;
110 
111 	return 0;
112 }
113 
114 static void fuse_truncate(struct address_space *mapping, loff_t offset)
115 {
116 	/* See vmtruncate() */
117 	unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
118 	truncate_inode_pages(mapping, offset);
119 	unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
120 }
121 
122 
123 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
124 			    u64 attr_valid, u64 attr_version)
125 {
126 	struct fuse_conn *fc = get_fuse_conn(inode);
127 	struct fuse_inode *fi = get_fuse_inode(inode);
128 	loff_t oldsize;
129 
130 	spin_lock(&fc->lock);
131 	if (attr_version != 0 && fi->attr_version > attr_version) {
132 		spin_unlock(&fc->lock);
133 		return;
134 	}
135 	fi->attr_version = ++fc->attr_version;
136 	fi->i_time = attr_valid;
137 
138 	inode->i_ino     = attr->ino;
139 	inode->i_mode    = (inode->i_mode & S_IFMT) | (attr->mode & 07777);
140 	inode->i_nlink   = attr->nlink;
141 	inode->i_uid     = attr->uid;
142 	inode->i_gid     = attr->gid;
143 	inode->i_blocks  = attr->blocks;
144 	inode->i_atime.tv_sec   = attr->atime;
145 	inode->i_atime.tv_nsec  = attr->atimensec;
146 	inode->i_mtime.tv_sec   = attr->mtime;
147 	inode->i_mtime.tv_nsec  = attr->mtimensec;
148 	inode->i_ctime.tv_sec   = attr->ctime;
149 	inode->i_ctime.tv_nsec  = attr->ctimensec;
150 
151 	if (attr->blksize != 0)
152 		inode->i_blkbits = ilog2(attr->blksize);
153 	else
154 		inode->i_blkbits = inode->i_sb->s_blocksize_bits;
155 
156 	/*
157 	 * Don't set the sticky bit in i_mode, unless we want the VFS
158 	 * to check permissions.  This prevents failures due to the
159 	 * check in may_delete().
160 	 */
161 	fi->orig_i_mode = inode->i_mode;
162 	if (!(fc->flags & FUSE_DEFAULT_PERMISSIONS))
163 		inode->i_mode &= ~S_ISVTX;
164 
165 	oldsize = inode->i_size;
166 	i_size_write(inode, attr->size);
167 	spin_unlock(&fc->lock);
168 
169 	if (S_ISREG(inode->i_mode) && oldsize != attr->size) {
170 		if (attr->size < oldsize)
171 			fuse_truncate(inode->i_mapping, attr->size);
172 		invalidate_inode_pages2(inode->i_mapping);
173 	}
174 }
175 
176 static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
177 {
178 	inode->i_mode = attr->mode & S_IFMT;
179 	inode->i_size = attr->size;
180 	if (S_ISREG(inode->i_mode)) {
181 		fuse_init_common(inode);
182 		fuse_init_file_inode(inode);
183 	} else if (S_ISDIR(inode->i_mode))
184 		fuse_init_dir(inode);
185 	else if (S_ISLNK(inode->i_mode))
186 		fuse_init_symlink(inode);
187 	else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
188 		 S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
189 		fuse_init_common(inode);
190 		init_special_inode(inode, inode->i_mode,
191 				   new_decode_dev(attr->rdev));
192 	} else
193 		BUG();
194 }
195 
196 static int fuse_inode_eq(struct inode *inode, void *_nodeidp)
197 {
198 	unsigned long nodeid = *(unsigned long *) _nodeidp;
199 	if (get_node_id(inode) == nodeid)
200 		return 1;
201 	else
202 		return 0;
203 }
204 
205 static int fuse_inode_set(struct inode *inode, void *_nodeidp)
206 {
207 	unsigned long nodeid = *(unsigned long *) _nodeidp;
208 	get_fuse_inode(inode)->nodeid = nodeid;
209 	return 0;
210 }
211 
212 struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
213 			int generation, struct fuse_attr *attr,
214 			u64 attr_valid, u64 attr_version)
215 {
216 	struct inode *inode;
217 	struct fuse_inode *fi;
218 	struct fuse_conn *fc = get_fuse_conn_super(sb);
219 
220  retry:
221 	inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);
222 	if (!inode)
223 		return NULL;
224 
225 	if ((inode->i_state & I_NEW)) {
226 		inode->i_flags |= S_NOATIME|S_NOCMTIME;
227 		inode->i_generation = generation;
228 		inode->i_data.backing_dev_info = &fc->bdi;
229 		fuse_init_inode(inode, attr);
230 		unlock_new_inode(inode);
231 	} else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
232 		/* Inode has changed type, any I/O on the old should fail */
233 		make_bad_inode(inode);
234 		iput(inode);
235 		goto retry;
236 	}
237 
238 	fi = get_fuse_inode(inode);
239 	spin_lock(&fc->lock);
240 	fi->nlookup ++;
241 	spin_unlock(&fc->lock);
242 	fuse_change_attributes(inode, attr, attr_valid, attr_version);
243 
244 	return inode;
245 }
246 
247 static void fuse_umount_begin(struct vfsmount *vfsmnt, int flags)
248 {
249 	if (flags & MNT_FORCE)
250 		fuse_abort_conn(get_fuse_conn_super(vfsmnt->mnt_sb));
251 }
252 
253 static void fuse_send_destroy(struct fuse_conn *fc)
254 {
255 	struct fuse_req *req = fc->destroy_req;
256 	if (req && fc->conn_init) {
257 		fc->destroy_req = NULL;
258 		req->in.h.opcode = FUSE_DESTROY;
259 		req->force = 1;
260 		request_send(fc, req);
261 		fuse_put_request(fc, req);
262 	}
263 }
264 
265 static void fuse_put_super(struct super_block *sb)
266 {
267 	struct fuse_conn *fc = get_fuse_conn_super(sb);
268 
269 	fuse_send_destroy(fc);
270 	spin_lock(&fc->lock);
271 	fc->connected = 0;
272 	fc->blocked = 0;
273 	spin_unlock(&fc->lock);
274 	/* Flush all readers on this fs */
275 	kill_fasync(&fc->fasync, SIGIO, POLL_IN);
276 	wake_up_all(&fc->waitq);
277 	wake_up_all(&fc->blocked_waitq);
278 	wake_up_all(&fc->reserved_req_waitq);
279 	mutex_lock(&fuse_mutex);
280 	list_del(&fc->entry);
281 	fuse_ctl_remove_conn(fc);
282 	mutex_unlock(&fuse_mutex);
283 	fuse_conn_put(fc);
284 }
285 
286 static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
287 {
288 	stbuf->f_type    = FUSE_SUPER_MAGIC;
289 	stbuf->f_bsize   = attr->bsize;
290 	stbuf->f_frsize  = attr->frsize;
291 	stbuf->f_blocks  = attr->blocks;
292 	stbuf->f_bfree   = attr->bfree;
293 	stbuf->f_bavail  = attr->bavail;
294 	stbuf->f_files   = attr->files;
295 	stbuf->f_ffree   = attr->ffree;
296 	stbuf->f_namelen = attr->namelen;
297 	/* fsid is left zero */
298 }
299 
300 static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)
301 {
302 	struct super_block *sb = dentry->d_sb;
303 	struct fuse_conn *fc = get_fuse_conn_super(sb);
304 	struct fuse_req *req;
305 	struct fuse_statfs_out outarg;
306 	int err;
307 
308 	if (!fuse_allow_task(fc, current)) {
309 		buf->f_type = FUSE_SUPER_MAGIC;
310 		return 0;
311 	}
312 
313 	req = fuse_get_req(fc);
314 	if (IS_ERR(req))
315 		return PTR_ERR(req);
316 
317 	memset(&outarg, 0, sizeof(outarg));
318 	req->in.numargs = 0;
319 	req->in.h.opcode = FUSE_STATFS;
320 	req->in.h.nodeid = get_node_id(dentry->d_inode);
321 	req->out.numargs = 1;
322 	req->out.args[0].size =
323 		fc->minor < 4 ? FUSE_COMPAT_STATFS_SIZE : sizeof(outarg);
324 	req->out.args[0].value = &outarg;
325 	request_send(fc, req);
326 	err = req->out.h.error;
327 	if (!err)
328 		convert_fuse_statfs(buf, &outarg.st);
329 	fuse_put_request(fc, req);
330 	return err;
331 }
332 
333 enum {
334 	OPT_FD,
335 	OPT_ROOTMODE,
336 	OPT_USER_ID,
337 	OPT_GROUP_ID,
338 	OPT_DEFAULT_PERMISSIONS,
339 	OPT_ALLOW_OTHER,
340 	OPT_MAX_READ,
341 	OPT_BLKSIZE,
342 	OPT_ERR
343 };
344 
345 static match_table_t tokens = {
346 	{OPT_FD,			"fd=%u"},
347 	{OPT_ROOTMODE,			"rootmode=%o"},
348 	{OPT_USER_ID,			"user_id=%u"},
349 	{OPT_GROUP_ID,			"group_id=%u"},
350 	{OPT_DEFAULT_PERMISSIONS,	"default_permissions"},
351 	{OPT_ALLOW_OTHER,		"allow_other"},
352 	{OPT_MAX_READ,			"max_read=%u"},
353 	{OPT_BLKSIZE,			"blksize=%u"},
354 	{OPT_ERR,			NULL}
355 };
356 
357 static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev)
358 {
359 	char *p;
360 	memset(d, 0, sizeof(struct fuse_mount_data));
361 	d->max_read = ~0;
362 	d->blksize = 512;
363 
364 	while ((p = strsep(&opt, ",")) != NULL) {
365 		int token;
366 		int value;
367 		substring_t args[MAX_OPT_ARGS];
368 		if (!*p)
369 			continue;
370 
371 		token = match_token(p, tokens, args);
372 		switch (token) {
373 		case OPT_FD:
374 			if (match_int(&args[0], &value))
375 				return 0;
376 			d->fd = value;
377 			d->fd_present = 1;
378 			break;
379 
380 		case OPT_ROOTMODE:
381 			if (match_octal(&args[0], &value))
382 				return 0;
383 			if (!fuse_valid_type(value))
384 				return 0;
385 			d->rootmode = value;
386 			d->rootmode_present = 1;
387 			break;
388 
389 		case OPT_USER_ID:
390 			if (match_int(&args[0], &value))
391 				return 0;
392 			d->user_id = value;
393 			d->user_id_present = 1;
394 			break;
395 
396 		case OPT_GROUP_ID:
397 			if (match_int(&args[0], &value))
398 				return 0;
399 			d->group_id = value;
400 			d->group_id_present = 1;
401 			break;
402 
403 		case OPT_DEFAULT_PERMISSIONS:
404 			d->flags |= FUSE_DEFAULT_PERMISSIONS;
405 			break;
406 
407 		case OPT_ALLOW_OTHER:
408 			d->flags |= FUSE_ALLOW_OTHER;
409 			break;
410 
411 		case OPT_MAX_READ:
412 			if (match_int(&args[0], &value))
413 				return 0;
414 			d->max_read = value;
415 			break;
416 
417 		case OPT_BLKSIZE:
418 			if (!is_bdev || match_int(&args[0], &value))
419 				return 0;
420 			d->blksize = value;
421 			break;
422 
423 		default:
424 			return 0;
425 		}
426 	}
427 
428 	if (!d->fd_present || !d->rootmode_present ||
429 	    !d->user_id_present || !d->group_id_present)
430 		return 0;
431 
432 	return 1;
433 }
434 
435 static int fuse_show_options(struct seq_file *m, struct vfsmount *mnt)
436 {
437 	struct fuse_conn *fc = get_fuse_conn_super(mnt->mnt_sb);
438 
439 	seq_printf(m, ",user_id=%u", fc->user_id);
440 	seq_printf(m, ",group_id=%u", fc->group_id);
441 	if (fc->flags & FUSE_DEFAULT_PERMISSIONS)
442 		seq_puts(m, ",default_permissions");
443 	if (fc->flags & FUSE_ALLOW_OTHER)
444 		seq_puts(m, ",allow_other");
445 	if (fc->max_read != ~0)
446 		seq_printf(m, ",max_read=%u", fc->max_read);
447 	return 0;
448 }
449 
450 static struct fuse_conn *new_conn(void)
451 {
452 	struct fuse_conn *fc;
453 	int err;
454 
455 	fc = kzalloc(sizeof(*fc), GFP_KERNEL);
456 	if (fc) {
457 		spin_lock_init(&fc->lock);
458 		mutex_init(&fc->inst_mutex);
459 		atomic_set(&fc->count, 1);
460 		init_waitqueue_head(&fc->waitq);
461 		init_waitqueue_head(&fc->blocked_waitq);
462 		init_waitqueue_head(&fc->reserved_req_waitq);
463 		INIT_LIST_HEAD(&fc->pending);
464 		INIT_LIST_HEAD(&fc->processing);
465 		INIT_LIST_HEAD(&fc->io);
466 		INIT_LIST_HEAD(&fc->interrupts);
467 		atomic_set(&fc->num_waiting, 0);
468 		fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
469 		fc->bdi.unplug_io_fn = default_unplug_io_fn;
470 		err = bdi_init(&fc->bdi);
471 		if (err) {
472 			kfree(fc);
473 			fc = NULL;
474 			goto out;
475 		}
476 		fc->reqctr = 0;
477 		fc->blocked = 1;
478 		fc->attr_version = 1;
479 		get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));
480 	}
481 out:
482 	return fc;
483 }
484 
485 void fuse_conn_put(struct fuse_conn *fc)
486 {
487 	if (atomic_dec_and_test(&fc->count)) {
488 		if (fc->destroy_req)
489 			fuse_request_free(fc->destroy_req);
490 		mutex_destroy(&fc->inst_mutex);
491 		bdi_destroy(&fc->bdi);
492 		kfree(fc);
493 	}
494 }
495 
496 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc)
497 {
498 	atomic_inc(&fc->count);
499 	return fc;
500 }
501 
502 static struct inode *get_root_inode(struct super_block *sb, unsigned mode)
503 {
504 	struct fuse_attr attr;
505 	memset(&attr, 0, sizeof(attr));
506 
507 	attr.mode = mode;
508 	attr.ino = FUSE_ROOT_ID;
509 	attr.nlink = 1;
510 	return fuse_iget(sb, 1, 0, &attr, 0, 0);
511 }
512 
513 static const struct super_operations fuse_super_operations = {
514 	.alloc_inode    = fuse_alloc_inode,
515 	.destroy_inode  = fuse_destroy_inode,
516 	.read_inode	= fuse_read_inode,
517 	.clear_inode	= fuse_clear_inode,
518 	.drop_inode	= generic_delete_inode,
519 	.remount_fs	= fuse_remount_fs,
520 	.put_super	= fuse_put_super,
521 	.umount_begin	= fuse_umount_begin,
522 	.statfs		= fuse_statfs,
523 	.show_options	= fuse_show_options,
524 };
525 
526 static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
527 {
528 	struct fuse_init_out *arg = &req->misc.init_out;
529 
530 	if (req->out.h.error || arg->major != FUSE_KERNEL_VERSION)
531 		fc->conn_error = 1;
532 	else {
533 		unsigned long ra_pages;
534 
535 		if (arg->minor >= 6) {
536 			ra_pages = arg->max_readahead / PAGE_CACHE_SIZE;
537 			if (arg->flags & FUSE_ASYNC_READ)
538 				fc->async_read = 1;
539 			if (!(arg->flags & FUSE_POSIX_LOCKS))
540 				fc->no_lock = 1;
541 			if (arg->flags & FUSE_ATOMIC_O_TRUNC)
542 				fc->atomic_o_trunc = 1;
543 		} else {
544 			ra_pages = fc->max_read / PAGE_CACHE_SIZE;
545 			fc->no_lock = 1;
546 		}
547 
548 		fc->bdi.ra_pages = min(fc->bdi.ra_pages, ra_pages);
549 		fc->minor = arg->minor;
550 		fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
551 		fc->conn_init = 1;
552 	}
553 	fuse_put_request(fc, req);
554 	fc->blocked = 0;
555 	wake_up_all(&fc->blocked_waitq);
556 }
557 
558 static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
559 {
560 	struct fuse_init_in *arg = &req->misc.init_in;
561 
562 	arg->major = FUSE_KERNEL_VERSION;
563 	arg->minor = FUSE_KERNEL_MINOR_VERSION;
564 	arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
565 	arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_FILE_OPS |
566 		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 decl_subsys(fuse, NULL, NULL);
748 static decl_subsys(connections, NULL, NULL);
749 
750 static void fuse_inode_init_once(struct kmem_cache *cachep, void *foo)
751 {
752 	struct inode * inode = foo;
753 
754 	inode_init_once(inode);
755 }
756 
757 static int __init fuse_fs_init(void)
758 {
759 	int err;
760 
761 	err = register_filesystem(&fuse_fs_type);
762 	if (err)
763 		goto out;
764 
765 	err = register_fuseblk();
766 	if (err)
767 		goto out_unreg;
768 
769 	fuse_inode_cachep = kmem_cache_create("fuse_inode",
770 					      sizeof(struct fuse_inode),
771 					      0, SLAB_HWCACHE_ALIGN,
772 					      fuse_inode_init_once);
773 	err = -ENOMEM;
774 	if (!fuse_inode_cachep)
775 		goto out_unreg2;
776 
777 	return 0;
778 
779  out_unreg2:
780 	unregister_fuseblk();
781  out_unreg:
782 	unregister_filesystem(&fuse_fs_type);
783  out:
784 	return err;
785 }
786 
787 static void fuse_fs_cleanup(void)
788 {
789 	unregister_filesystem(&fuse_fs_type);
790 	unregister_fuseblk();
791 	kmem_cache_destroy(fuse_inode_cachep);
792 }
793 
794 static int fuse_sysfs_init(void)
795 {
796 	int err;
797 
798 	kobj_set_kset_s(&fuse_subsys, fs_subsys);
799 	err = subsystem_register(&fuse_subsys);
800 	if (err)
801 		goto out_err;
802 
803 	kobj_set_kset_s(&connections_subsys, fuse_subsys);
804 	err = subsystem_register(&connections_subsys);
805 	if (err)
806 		goto out_fuse_unregister;
807 
808 	return 0;
809 
810  out_fuse_unregister:
811 	subsystem_unregister(&fuse_subsys);
812  out_err:
813 	return err;
814 }
815 
816 static void fuse_sysfs_cleanup(void)
817 {
818 	subsystem_unregister(&connections_subsys);
819 	subsystem_unregister(&fuse_subsys);
820 }
821 
822 static int __init fuse_init(void)
823 {
824 	int res;
825 
826 	printk("fuse init (API version %i.%i)\n",
827 	       FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
828 
829 	INIT_LIST_HEAD(&fuse_conn_list);
830 	res = fuse_fs_init();
831 	if (res)
832 		goto err;
833 
834 	res = fuse_dev_init();
835 	if (res)
836 		goto err_fs_cleanup;
837 
838 	res = fuse_sysfs_init();
839 	if (res)
840 		goto err_dev_cleanup;
841 
842 	res = fuse_ctl_init();
843 	if (res)
844 		goto err_sysfs_cleanup;
845 
846 	return 0;
847 
848  err_sysfs_cleanup:
849 	fuse_sysfs_cleanup();
850  err_dev_cleanup:
851 	fuse_dev_cleanup();
852  err_fs_cleanup:
853 	fuse_fs_cleanup();
854  err:
855 	return res;
856 }
857 
858 static void __exit fuse_exit(void)
859 {
860 	printk(KERN_DEBUG "fuse exit\n");
861 
862 	fuse_ctl_cleanup();
863 	fuse_sysfs_cleanup();
864 	fuse_fs_cleanup();
865 	fuse_dev_cleanup();
866 }
867 
868 module_init(fuse_init);
869 module_exit(fuse_exit);
870