xref: /openbmc/linux/fs/fuse/inode.c (revision afb46f79)
1 /*
2   FUSE: Filesystem in Userspace
3   Copyright (C) 2001-2008  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/moduleparam.h>
18 #include <linux/parser.h>
19 #include <linux/statfs.h>
20 #include <linux/random.h>
21 #include <linux/sched.h>
22 #include <linux/exportfs.h>
23 
24 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
25 MODULE_DESCRIPTION("Filesystem in Userspace");
26 MODULE_LICENSE("GPL");
27 
28 static struct kmem_cache *fuse_inode_cachep;
29 struct list_head fuse_conn_list;
30 DEFINE_MUTEX(fuse_mutex);
31 
32 static int set_global_limit(const char *val, struct kernel_param *kp);
33 
34 unsigned max_user_bgreq;
35 module_param_call(max_user_bgreq, set_global_limit, param_get_uint,
36 		  &max_user_bgreq, 0644);
37 __MODULE_PARM_TYPE(max_user_bgreq, "uint");
38 MODULE_PARM_DESC(max_user_bgreq,
39  "Global limit for the maximum number of backgrounded requests an "
40  "unprivileged user can set");
41 
42 unsigned max_user_congthresh;
43 module_param_call(max_user_congthresh, set_global_limit, param_get_uint,
44 		  &max_user_congthresh, 0644);
45 __MODULE_PARM_TYPE(max_user_congthresh, "uint");
46 MODULE_PARM_DESC(max_user_congthresh,
47  "Global limit for the maximum congestion threshold an "
48  "unprivileged user can set");
49 
50 #define FUSE_SUPER_MAGIC 0x65735546
51 
52 #define FUSE_DEFAULT_BLKSIZE 512
53 
54 /** Maximum number of outstanding background requests */
55 #define FUSE_DEFAULT_MAX_BACKGROUND 12
56 
57 /** Congestion starts at 75% of maximum */
58 #define FUSE_DEFAULT_CONGESTION_THRESHOLD (FUSE_DEFAULT_MAX_BACKGROUND * 3 / 4)
59 
60 struct fuse_mount_data {
61 	int fd;
62 	unsigned rootmode;
63 	kuid_t user_id;
64 	kgid_t group_id;
65 	unsigned fd_present:1;
66 	unsigned rootmode_present:1;
67 	unsigned user_id_present:1;
68 	unsigned group_id_present:1;
69 	unsigned flags;
70 	unsigned max_read;
71 	unsigned blksize;
72 };
73 
74 struct fuse_forget_link *fuse_alloc_forget(void)
75 {
76 	return kzalloc(sizeof(struct fuse_forget_link), GFP_KERNEL);
77 }
78 
79 static struct inode *fuse_alloc_inode(struct super_block *sb)
80 {
81 	struct inode *inode;
82 	struct fuse_inode *fi;
83 
84 	inode = kmem_cache_alloc(fuse_inode_cachep, GFP_KERNEL);
85 	if (!inode)
86 		return NULL;
87 
88 	fi = get_fuse_inode(inode);
89 	fi->i_time = 0;
90 	fi->nodeid = 0;
91 	fi->nlookup = 0;
92 	fi->attr_version = 0;
93 	fi->writectr = 0;
94 	fi->orig_ino = 0;
95 	fi->state = 0;
96 	INIT_LIST_HEAD(&fi->write_files);
97 	INIT_LIST_HEAD(&fi->queued_writes);
98 	INIT_LIST_HEAD(&fi->writepages);
99 	init_waitqueue_head(&fi->page_waitq);
100 	fi->forget = fuse_alloc_forget();
101 	if (!fi->forget) {
102 		kmem_cache_free(fuse_inode_cachep, inode);
103 		return NULL;
104 	}
105 
106 	return inode;
107 }
108 
109 static void fuse_i_callback(struct rcu_head *head)
110 {
111 	struct inode *inode = container_of(head, struct inode, i_rcu);
112 	kmem_cache_free(fuse_inode_cachep, inode);
113 }
114 
115 static void fuse_destroy_inode(struct inode *inode)
116 {
117 	struct fuse_inode *fi = get_fuse_inode(inode);
118 	BUG_ON(!list_empty(&fi->write_files));
119 	BUG_ON(!list_empty(&fi->queued_writes));
120 	kfree(fi->forget);
121 	call_rcu(&inode->i_rcu, fuse_i_callback);
122 }
123 
124 static void fuse_evict_inode(struct inode *inode)
125 {
126 	truncate_inode_pages_final(&inode->i_data);
127 	clear_inode(inode);
128 	if (inode->i_sb->s_flags & MS_ACTIVE) {
129 		struct fuse_conn *fc = get_fuse_conn(inode);
130 		struct fuse_inode *fi = get_fuse_inode(inode);
131 		fuse_queue_forget(fc, fi->forget, fi->nodeid, fi->nlookup);
132 		fi->forget = NULL;
133 	}
134 }
135 
136 static int fuse_remount_fs(struct super_block *sb, int *flags, char *data)
137 {
138 	sync_filesystem(sb);
139 	if (*flags & MS_MANDLOCK)
140 		return -EINVAL;
141 
142 	return 0;
143 }
144 
145 /*
146  * ino_t is 32-bits on 32-bit arch. We have to squash the 64-bit value down
147  * so that it will fit.
148  */
149 static ino_t fuse_squash_ino(u64 ino64)
150 {
151 	ino_t ino = (ino_t) ino64;
152 	if (sizeof(ino_t) < sizeof(u64))
153 		ino ^= ino64 >> (sizeof(u64) - sizeof(ino_t)) * 8;
154 	return ino;
155 }
156 
157 void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
158 				   u64 attr_valid)
159 {
160 	struct fuse_conn *fc = get_fuse_conn(inode);
161 	struct fuse_inode *fi = get_fuse_inode(inode);
162 
163 	fi->attr_version = ++fc->attr_version;
164 	fi->i_time = attr_valid;
165 
166 	inode->i_ino     = fuse_squash_ino(attr->ino);
167 	inode->i_mode    = (inode->i_mode & S_IFMT) | (attr->mode & 07777);
168 	set_nlink(inode, attr->nlink);
169 	inode->i_uid     = make_kuid(&init_user_ns, attr->uid);
170 	inode->i_gid     = make_kgid(&init_user_ns, attr->gid);
171 	inode->i_blocks  = attr->blocks;
172 	inode->i_atime.tv_sec   = attr->atime;
173 	inode->i_atime.tv_nsec  = attr->atimensec;
174 	/* mtime from server may be stale due to local buffered write */
175 	if (!fc->writeback_cache || !S_ISREG(inode->i_mode)) {
176 		inode->i_mtime.tv_sec   = attr->mtime;
177 		inode->i_mtime.tv_nsec  = attr->mtimensec;
178 	}
179 	inode->i_ctime.tv_sec   = attr->ctime;
180 	inode->i_ctime.tv_nsec  = attr->ctimensec;
181 
182 	if (attr->blksize != 0)
183 		inode->i_blkbits = ilog2(attr->blksize);
184 	else
185 		inode->i_blkbits = inode->i_sb->s_blocksize_bits;
186 
187 	/*
188 	 * Don't set the sticky bit in i_mode, unless we want the VFS
189 	 * to check permissions.  This prevents failures due to the
190 	 * check in may_delete().
191 	 */
192 	fi->orig_i_mode = inode->i_mode;
193 	if (!(fc->flags & FUSE_DEFAULT_PERMISSIONS))
194 		inode->i_mode &= ~S_ISVTX;
195 
196 	fi->orig_ino = attr->ino;
197 }
198 
199 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
200 			    u64 attr_valid, u64 attr_version)
201 {
202 	struct fuse_conn *fc = get_fuse_conn(inode);
203 	struct fuse_inode *fi = get_fuse_inode(inode);
204 	bool is_wb = fc->writeback_cache;
205 	loff_t oldsize;
206 	struct timespec old_mtime;
207 
208 	spin_lock(&fc->lock);
209 	if ((attr_version != 0 && fi->attr_version > attr_version) ||
210 	    test_bit(FUSE_I_SIZE_UNSTABLE, &fi->state)) {
211 		spin_unlock(&fc->lock);
212 		return;
213 	}
214 
215 	old_mtime = inode->i_mtime;
216 	fuse_change_attributes_common(inode, attr, attr_valid);
217 
218 	oldsize = inode->i_size;
219 	/*
220 	 * In case of writeback_cache enabled, the cached writes beyond EOF
221 	 * extend local i_size without keeping userspace server in sync. So,
222 	 * attr->size coming from server can be stale. We cannot trust it.
223 	 */
224 	if (!is_wb || !S_ISREG(inode->i_mode))
225 		i_size_write(inode, attr->size);
226 	spin_unlock(&fc->lock);
227 
228 	if (!is_wb && S_ISREG(inode->i_mode)) {
229 		bool inval = false;
230 
231 		if (oldsize != attr->size) {
232 			truncate_pagecache(inode, attr->size);
233 			inval = true;
234 		} else if (fc->auto_inval_data) {
235 			struct timespec new_mtime = {
236 				.tv_sec = attr->mtime,
237 				.tv_nsec = attr->mtimensec,
238 			};
239 
240 			/*
241 			 * Auto inval mode also checks and invalidates if mtime
242 			 * has changed.
243 			 */
244 			if (!timespec_equal(&old_mtime, &new_mtime))
245 				inval = true;
246 		}
247 
248 		if (inval)
249 			invalidate_inode_pages2(inode->i_mapping);
250 	}
251 }
252 
253 static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
254 {
255 	inode->i_mode = attr->mode & S_IFMT;
256 	inode->i_size = attr->size;
257 	inode->i_mtime.tv_sec  = attr->mtime;
258 	inode->i_mtime.tv_nsec = attr->mtimensec;
259 	if (S_ISREG(inode->i_mode)) {
260 		fuse_init_common(inode);
261 		fuse_init_file_inode(inode);
262 	} else if (S_ISDIR(inode->i_mode))
263 		fuse_init_dir(inode);
264 	else if (S_ISLNK(inode->i_mode))
265 		fuse_init_symlink(inode);
266 	else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
267 		 S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
268 		fuse_init_common(inode);
269 		init_special_inode(inode, inode->i_mode,
270 				   new_decode_dev(attr->rdev));
271 	} else
272 		BUG();
273 }
274 
275 int fuse_inode_eq(struct inode *inode, void *_nodeidp)
276 {
277 	u64 nodeid = *(u64 *) _nodeidp;
278 	if (get_node_id(inode) == nodeid)
279 		return 1;
280 	else
281 		return 0;
282 }
283 
284 static int fuse_inode_set(struct inode *inode, void *_nodeidp)
285 {
286 	u64 nodeid = *(u64 *) _nodeidp;
287 	get_fuse_inode(inode)->nodeid = nodeid;
288 	return 0;
289 }
290 
291 struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
292 			int generation, struct fuse_attr *attr,
293 			u64 attr_valid, u64 attr_version)
294 {
295 	struct inode *inode;
296 	struct fuse_inode *fi;
297 	struct fuse_conn *fc = get_fuse_conn_super(sb);
298 
299  retry:
300 	inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);
301 	if (!inode)
302 		return NULL;
303 
304 	if ((inode->i_state & I_NEW)) {
305 		inode->i_flags |= S_NOATIME;
306 		if (!fc->writeback_cache || !S_ISREG(inode->i_mode))
307 			inode->i_flags |= S_NOCMTIME;
308 		inode->i_generation = generation;
309 		inode->i_data.backing_dev_info = &fc->bdi;
310 		fuse_init_inode(inode, attr);
311 		unlock_new_inode(inode);
312 	} else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
313 		/* Inode has changed type, any I/O on the old should fail */
314 		make_bad_inode(inode);
315 		iput(inode);
316 		goto retry;
317 	}
318 
319 	fi = get_fuse_inode(inode);
320 	spin_lock(&fc->lock);
321 	fi->nlookup++;
322 	spin_unlock(&fc->lock);
323 	fuse_change_attributes(inode, attr, attr_valid, attr_version);
324 
325 	return inode;
326 }
327 
328 int fuse_reverse_inval_inode(struct super_block *sb, u64 nodeid,
329 			     loff_t offset, loff_t len)
330 {
331 	struct inode *inode;
332 	pgoff_t pg_start;
333 	pgoff_t pg_end;
334 
335 	inode = ilookup5(sb, nodeid, fuse_inode_eq, &nodeid);
336 	if (!inode)
337 		return -ENOENT;
338 
339 	fuse_invalidate_attr(inode);
340 	if (offset >= 0) {
341 		pg_start = offset >> PAGE_CACHE_SHIFT;
342 		if (len <= 0)
343 			pg_end = -1;
344 		else
345 			pg_end = (offset + len - 1) >> PAGE_CACHE_SHIFT;
346 		invalidate_inode_pages2_range(inode->i_mapping,
347 					      pg_start, pg_end);
348 	}
349 	iput(inode);
350 	return 0;
351 }
352 
353 static void fuse_umount_begin(struct super_block *sb)
354 {
355 	fuse_abort_conn(get_fuse_conn_super(sb));
356 }
357 
358 static void fuse_send_destroy(struct fuse_conn *fc)
359 {
360 	struct fuse_req *req = fc->destroy_req;
361 	if (req && fc->conn_init) {
362 		fc->destroy_req = NULL;
363 		req->in.h.opcode = FUSE_DESTROY;
364 		req->force = 1;
365 		req->background = 0;
366 		fuse_request_send(fc, req);
367 		fuse_put_request(fc, req);
368 	}
369 }
370 
371 static void fuse_bdi_destroy(struct fuse_conn *fc)
372 {
373 	if (fc->bdi_initialized)
374 		bdi_destroy(&fc->bdi);
375 }
376 
377 void fuse_conn_kill(struct fuse_conn *fc)
378 {
379 	spin_lock(&fc->lock);
380 	fc->connected = 0;
381 	fc->blocked = 0;
382 	fc->initialized = 1;
383 	spin_unlock(&fc->lock);
384 	/* Flush all readers on this fs */
385 	kill_fasync(&fc->fasync, SIGIO, POLL_IN);
386 	wake_up_all(&fc->waitq);
387 	wake_up_all(&fc->blocked_waitq);
388 	wake_up_all(&fc->reserved_req_waitq);
389 }
390 EXPORT_SYMBOL_GPL(fuse_conn_kill);
391 
392 static void fuse_put_super(struct super_block *sb)
393 {
394 	struct fuse_conn *fc = get_fuse_conn_super(sb);
395 
396 	fuse_send_destroy(fc);
397 
398 	fuse_conn_kill(fc);
399 	mutex_lock(&fuse_mutex);
400 	list_del(&fc->entry);
401 	fuse_ctl_remove_conn(fc);
402 	mutex_unlock(&fuse_mutex);
403 	fuse_bdi_destroy(fc);
404 
405 	fuse_conn_put(fc);
406 }
407 
408 static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
409 {
410 	stbuf->f_type    = FUSE_SUPER_MAGIC;
411 	stbuf->f_bsize   = attr->bsize;
412 	stbuf->f_frsize  = attr->frsize;
413 	stbuf->f_blocks  = attr->blocks;
414 	stbuf->f_bfree   = attr->bfree;
415 	stbuf->f_bavail  = attr->bavail;
416 	stbuf->f_files   = attr->files;
417 	stbuf->f_ffree   = attr->ffree;
418 	stbuf->f_namelen = attr->namelen;
419 	/* fsid is left zero */
420 }
421 
422 static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)
423 {
424 	struct super_block *sb = dentry->d_sb;
425 	struct fuse_conn *fc = get_fuse_conn_super(sb);
426 	struct fuse_req *req;
427 	struct fuse_statfs_out outarg;
428 	int err;
429 
430 	if (!fuse_allow_current_process(fc)) {
431 		buf->f_type = FUSE_SUPER_MAGIC;
432 		return 0;
433 	}
434 
435 	req = fuse_get_req_nopages(fc);
436 	if (IS_ERR(req))
437 		return PTR_ERR(req);
438 
439 	memset(&outarg, 0, sizeof(outarg));
440 	req->in.numargs = 0;
441 	req->in.h.opcode = FUSE_STATFS;
442 	req->in.h.nodeid = get_node_id(dentry->d_inode);
443 	req->out.numargs = 1;
444 	req->out.args[0].size =
445 		fc->minor < 4 ? FUSE_COMPAT_STATFS_SIZE : sizeof(outarg);
446 	req->out.args[0].value = &outarg;
447 	fuse_request_send(fc, req);
448 	err = req->out.h.error;
449 	if (!err)
450 		convert_fuse_statfs(buf, &outarg.st);
451 	fuse_put_request(fc, req);
452 	return err;
453 }
454 
455 enum {
456 	OPT_FD,
457 	OPT_ROOTMODE,
458 	OPT_USER_ID,
459 	OPT_GROUP_ID,
460 	OPT_DEFAULT_PERMISSIONS,
461 	OPT_ALLOW_OTHER,
462 	OPT_MAX_READ,
463 	OPT_BLKSIZE,
464 	OPT_ERR
465 };
466 
467 static const match_table_t tokens = {
468 	{OPT_FD,			"fd=%u"},
469 	{OPT_ROOTMODE,			"rootmode=%o"},
470 	{OPT_USER_ID,			"user_id=%u"},
471 	{OPT_GROUP_ID,			"group_id=%u"},
472 	{OPT_DEFAULT_PERMISSIONS,	"default_permissions"},
473 	{OPT_ALLOW_OTHER,		"allow_other"},
474 	{OPT_MAX_READ,			"max_read=%u"},
475 	{OPT_BLKSIZE,			"blksize=%u"},
476 	{OPT_ERR,			NULL}
477 };
478 
479 static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev)
480 {
481 	char *p;
482 	memset(d, 0, sizeof(struct fuse_mount_data));
483 	d->max_read = ~0;
484 	d->blksize = FUSE_DEFAULT_BLKSIZE;
485 
486 	while ((p = strsep(&opt, ",")) != NULL) {
487 		int token;
488 		int value;
489 		substring_t args[MAX_OPT_ARGS];
490 		if (!*p)
491 			continue;
492 
493 		token = match_token(p, tokens, args);
494 		switch (token) {
495 		case OPT_FD:
496 			if (match_int(&args[0], &value))
497 				return 0;
498 			d->fd = value;
499 			d->fd_present = 1;
500 			break;
501 
502 		case OPT_ROOTMODE:
503 			if (match_octal(&args[0], &value))
504 				return 0;
505 			if (!fuse_valid_type(value))
506 				return 0;
507 			d->rootmode = value;
508 			d->rootmode_present = 1;
509 			break;
510 
511 		case OPT_USER_ID:
512 			if (match_int(&args[0], &value))
513 				return 0;
514 			d->user_id = make_kuid(current_user_ns(), value);
515 			if (!uid_valid(d->user_id))
516 				return 0;
517 			d->user_id_present = 1;
518 			break;
519 
520 		case OPT_GROUP_ID:
521 			if (match_int(&args[0], &value))
522 				return 0;
523 			d->group_id = make_kgid(current_user_ns(), value);
524 			if (!gid_valid(d->group_id))
525 				return 0;
526 			d->group_id_present = 1;
527 			break;
528 
529 		case OPT_DEFAULT_PERMISSIONS:
530 			d->flags |= FUSE_DEFAULT_PERMISSIONS;
531 			break;
532 
533 		case OPT_ALLOW_OTHER:
534 			d->flags |= FUSE_ALLOW_OTHER;
535 			break;
536 
537 		case OPT_MAX_READ:
538 			if (match_int(&args[0], &value))
539 				return 0;
540 			d->max_read = value;
541 			break;
542 
543 		case OPT_BLKSIZE:
544 			if (!is_bdev || match_int(&args[0], &value))
545 				return 0;
546 			d->blksize = value;
547 			break;
548 
549 		default:
550 			return 0;
551 		}
552 	}
553 
554 	if (!d->fd_present || !d->rootmode_present ||
555 	    !d->user_id_present || !d->group_id_present)
556 		return 0;
557 
558 	return 1;
559 }
560 
561 static int fuse_show_options(struct seq_file *m, struct dentry *root)
562 {
563 	struct super_block *sb = root->d_sb;
564 	struct fuse_conn *fc = get_fuse_conn_super(sb);
565 
566 	seq_printf(m, ",user_id=%u", from_kuid_munged(&init_user_ns, fc->user_id));
567 	seq_printf(m, ",group_id=%u", from_kgid_munged(&init_user_ns, fc->group_id));
568 	if (fc->flags & FUSE_DEFAULT_PERMISSIONS)
569 		seq_puts(m, ",default_permissions");
570 	if (fc->flags & FUSE_ALLOW_OTHER)
571 		seq_puts(m, ",allow_other");
572 	if (fc->max_read != ~0)
573 		seq_printf(m, ",max_read=%u", fc->max_read);
574 	if (sb->s_bdev && sb->s_blocksize != FUSE_DEFAULT_BLKSIZE)
575 		seq_printf(m, ",blksize=%lu", sb->s_blocksize);
576 	return 0;
577 }
578 
579 void fuse_conn_init(struct fuse_conn *fc)
580 {
581 	memset(fc, 0, sizeof(*fc));
582 	spin_lock_init(&fc->lock);
583 	init_rwsem(&fc->killsb);
584 	atomic_set(&fc->count, 1);
585 	init_waitqueue_head(&fc->waitq);
586 	init_waitqueue_head(&fc->blocked_waitq);
587 	init_waitqueue_head(&fc->reserved_req_waitq);
588 	INIT_LIST_HEAD(&fc->pending);
589 	INIT_LIST_HEAD(&fc->processing);
590 	INIT_LIST_HEAD(&fc->io);
591 	INIT_LIST_HEAD(&fc->interrupts);
592 	INIT_LIST_HEAD(&fc->bg_queue);
593 	INIT_LIST_HEAD(&fc->entry);
594 	fc->forget_list_tail = &fc->forget_list_head;
595 	atomic_set(&fc->num_waiting, 0);
596 	fc->max_background = FUSE_DEFAULT_MAX_BACKGROUND;
597 	fc->congestion_threshold = FUSE_DEFAULT_CONGESTION_THRESHOLD;
598 	fc->khctr = 0;
599 	fc->polled_files = RB_ROOT;
600 	fc->reqctr = 0;
601 	fc->blocked = 0;
602 	fc->initialized = 0;
603 	fc->attr_version = 1;
604 	get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));
605 }
606 EXPORT_SYMBOL_GPL(fuse_conn_init);
607 
608 void fuse_conn_put(struct fuse_conn *fc)
609 {
610 	if (atomic_dec_and_test(&fc->count)) {
611 		if (fc->destroy_req)
612 			fuse_request_free(fc->destroy_req);
613 		fc->release(fc);
614 	}
615 }
616 EXPORT_SYMBOL_GPL(fuse_conn_put);
617 
618 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc)
619 {
620 	atomic_inc(&fc->count);
621 	return fc;
622 }
623 EXPORT_SYMBOL_GPL(fuse_conn_get);
624 
625 static struct inode *fuse_get_root_inode(struct super_block *sb, unsigned mode)
626 {
627 	struct fuse_attr attr;
628 	memset(&attr, 0, sizeof(attr));
629 
630 	attr.mode = mode;
631 	attr.ino = FUSE_ROOT_ID;
632 	attr.nlink = 1;
633 	return fuse_iget(sb, 1, 0, &attr, 0, 0);
634 }
635 
636 struct fuse_inode_handle {
637 	u64 nodeid;
638 	u32 generation;
639 };
640 
641 static struct dentry *fuse_get_dentry(struct super_block *sb,
642 				      struct fuse_inode_handle *handle)
643 {
644 	struct fuse_conn *fc = get_fuse_conn_super(sb);
645 	struct inode *inode;
646 	struct dentry *entry;
647 	int err = -ESTALE;
648 
649 	if (handle->nodeid == 0)
650 		goto out_err;
651 
652 	inode = ilookup5(sb, handle->nodeid, fuse_inode_eq, &handle->nodeid);
653 	if (!inode) {
654 		struct fuse_entry_out outarg;
655 		struct qstr name;
656 
657 		if (!fc->export_support)
658 			goto out_err;
659 
660 		name.len = 1;
661 		name.name = ".";
662 		err = fuse_lookup_name(sb, handle->nodeid, &name, &outarg,
663 				       &inode);
664 		if (err && err != -ENOENT)
665 			goto out_err;
666 		if (err || !inode) {
667 			err = -ESTALE;
668 			goto out_err;
669 		}
670 		err = -EIO;
671 		if (get_node_id(inode) != handle->nodeid)
672 			goto out_iput;
673 	}
674 	err = -ESTALE;
675 	if (inode->i_generation != handle->generation)
676 		goto out_iput;
677 
678 	entry = d_obtain_alias(inode);
679 	if (!IS_ERR(entry) && get_node_id(inode) != FUSE_ROOT_ID)
680 		fuse_invalidate_entry_cache(entry);
681 
682 	return entry;
683 
684  out_iput:
685 	iput(inode);
686  out_err:
687 	return ERR_PTR(err);
688 }
689 
690 static int fuse_encode_fh(struct inode *inode, u32 *fh, int *max_len,
691 			   struct inode *parent)
692 {
693 	int len = parent ? 6 : 3;
694 	u64 nodeid;
695 	u32 generation;
696 
697 	if (*max_len < len) {
698 		*max_len = len;
699 		return  FILEID_INVALID;
700 	}
701 
702 	nodeid = get_fuse_inode(inode)->nodeid;
703 	generation = inode->i_generation;
704 
705 	fh[0] = (u32)(nodeid >> 32);
706 	fh[1] = (u32)(nodeid & 0xffffffff);
707 	fh[2] = generation;
708 
709 	if (parent) {
710 		nodeid = get_fuse_inode(parent)->nodeid;
711 		generation = parent->i_generation;
712 
713 		fh[3] = (u32)(nodeid >> 32);
714 		fh[4] = (u32)(nodeid & 0xffffffff);
715 		fh[5] = generation;
716 	}
717 
718 	*max_len = len;
719 	return parent ? 0x82 : 0x81;
720 }
721 
722 static struct dentry *fuse_fh_to_dentry(struct super_block *sb,
723 		struct fid *fid, int fh_len, int fh_type)
724 {
725 	struct fuse_inode_handle handle;
726 
727 	if ((fh_type != 0x81 && fh_type != 0x82) || fh_len < 3)
728 		return NULL;
729 
730 	handle.nodeid = (u64) fid->raw[0] << 32;
731 	handle.nodeid |= (u64) fid->raw[1];
732 	handle.generation = fid->raw[2];
733 	return fuse_get_dentry(sb, &handle);
734 }
735 
736 static struct dentry *fuse_fh_to_parent(struct super_block *sb,
737 		struct fid *fid, int fh_len, int fh_type)
738 {
739 	struct fuse_inode_handle parent;
740 
741 	if (fh_type != 0x82 || fh_len < 6)
742 		return NULL;
743 
744 	parent.nodeid = (u64) fid->raw[3] << 32;
745 	parent.nodeid |= (u64) fid->raw[4];
746 	parent.generation = fid->raw[5];
747 	return fuse_get_dentry(sb, &parent);
748 }
749 
750 static struct dentry *fuse_get_parent(struct dentry *child)
751 {
752 	struct inode *child_inode = child->d_inode;
753 	struct fuse_conn *fc = get_fuse_conn(child_inode);
754 	struct inode *inode;
755 	struct dentry *parent;
756 	struct fuse_entry_out outarg;
757 	struct qstr name;
758 	int err;
759 
760 	if (!fc->export_support)
761 		return ERR_PTR(-ESTALE);
762 
763 	name.len = 2;
764 	name.name = "..";
765 	err = fuse_lookup_name(child_inode->i_sb, get_node_id(child_inode),
766 			       &name, &outarg, &inode);
767 	if (err) {
768 		if (err == -ENOENT)
769 			return ERR_PTR(-ESTALE);
770 		return ERR_PTR(err);
771 	}
772 
773 	parent = d_obtain_alias(inode);
774 	if (!IS_ERR(parent) && get_node_id(inode) != FUSE_ROOT_ID)
775 		fuse_invalidate_entry_cache(parent);
776 
777 	return parent;
778 }
779 
780 static const struct export_operations fuse_export_operations = {
781 	.fh_to_dentry	= fuse_fh_to_dentry,
782 	.fh_to_parent	= fuse_fh_to_parent,
783 	.encode_fh	= fuse_encode_fh,
784 	.get_parent	= fuse_get_parent,
785 };
786 
787 static const struct super_operations fuse_super_operations = {
788 	.alloc_inode    = fuse_alloc_inode,
789 	.destroy_inode  = fuse_destroy_inode,
790 	.evict_inode	= fuse_evict_inode,
791 	.drop_inode	= generic_delete_inode,
792 	.remount_fs	= fuse_remount_fs,
793 	.put_super	= fuse_put_super,
794 	.umount_begin	= fuse_umount_begin,
795 	.statfs		= fuse_statfs,
796 	.show_options	= fuse_show_options,
797 };
798 
799 static void sanitize_global_limit(unsigned *limit)
800 {
801 	if (*limit == 0)
802 		*limit = ((totalram_pages << PAGE_SHIFT) >> 13) /
803 			 sizeof(struct fuse_req);
804 
805 	if (*limit >= 1 << 16)
806 		*limit = (1 << 16) - 1;
807 }
808 
809 static int set_global_limit(const char *val, struct kernel_param *kp)
810 {
811 	int rv;
812 
813 	rv = param_set_uint(val, kp);
814 	if (rv)
815 		return rv;
816 
817 	sanitize_global_limit((unsigned *)kp->arg);
818 
819 	return 0;
820 }
821 
822 static void process_init_limits(struct fuse_conn *fc, struct fuse_init_out *arg)
823 {
824 	int cap_sys_admin = capable(CAP_SYS_ADMIN);
825 
826 	if (arg->minor < 13)
827 		return;
828 
829 	sanitize_global_limit(&max_user_bgreq);
830 	sanitize_global_limit(&max_user_congthresh);
831 
832 	if (arg->max_background) {
833 		fc->max_background = arg->max_background;
834 
835 		if (!cap_sys_admin && fc->max_background > max_user_bgreq)
836 			fc->max_background = max_user_bgreq;
837 	}
838 	if (arg->congestion_threshold) {
839 		fc->congestion_threshold = arg->congestion_threshold;
840 
841 		if (!cap_sys_admin &&
842 		    fc->congestion_threshold > max_user_congthresh)
843 			fc->congestion_threshold = max_user_congthresh;
844 	}
845 }
846 
847 static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
848 {
849 	struct fuse_init_out *arg = &req->misc.init_out;
850 
851 	if (req->out.h.error || arg->major != FUSE_KERNEL_VERSION)
852 		fc->conn_error = 1;
853 	else {
854 		unsigned long ra_pages;
855 
856 		process_init_limits(fc, arg);
857 
858 		if (arg->minor >= 6) {
859 			ra_pages = arg->max_readahead / PAGE_CACHE_SIZE;
860 			if (arg->flags & FUSE_ASYNC_READ)
861 				fc->async_read = 1;
862 			if (!(arg->flags & FUSE_POSIX_LOCKS))
863 				fc->no_lock = 1;
864 			if (arg->minor >= 17) {
865 				if (!(arg->flags & FUSE_FLOCK_LOCKS))
866 					fc->no_flock = 1;
867 			} else {
868 				if (!(arg->flags & FUSE_POSIX_LOCKS))
869 					fc->no_flock = 1;
870 			}
871 			if (arg->flags & FUSE_ATOMIC_O_TRUNC)
872 				fc->atomic_o_trunc = 1;
873 			if (arg->minor >= 9) {
874 				/* LOOKUP has dependency on proto version */
875 				if (arg->flags & FUSE_EXPORT_SUPPORT)
876 					fc->export_support = 1;
877 			}
878 			if (arg->flags & FUSE_BIG_WRITES)
879 				fc->big_writes = 1;
880 			if (arg->flags & FUSE_DONT_MASK)
881 				fc->dont_mask = 1;
882 			if (arg->flags & FUSE_AUTO_INVAL_DATA)
883 				fc->auto_inval_data = 1;
884 			if (arg->flags & FUSE_DO_READDIRPLUS) {
885 				fc->do_readdirplus = 1;
886 				if (arg->flags & FUSE_READDIRPLUS_AUTO)
887 					fc->readdirplus_auto = 1;
888 			}
889 			if (arg->flags & FUSE_ASYNC_DIO)
890 				fc->async_dio = 1;
891 			if (arg->flags & FUSE_WRITEBACK_CACHE)
892 				fc->writeback_cache = 1;
893 		} else {
894 			ra_pages = fc->max_read / PAGE_CACHE_SIZE;
895 			fc->no_lock = 1;
896 			fc->no_flock = 1;
897 		}
898 
899 		fc->bdi.ra_pages = min(fc->bdi.ra_pages, ra_pages);
900 		fc->minor = arg->minor;
901 		fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
902 		fc->max_write = max_t(unsigned, 4096, fc->max_write);
903 		fc->conn_init = 1;
904 	}
905 	fc->initialized = 1;
906 	wake_up_all(&fc->blocked_waitq);
907 }
908 
909 static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
910 {
911 	struct fuse_init_in *arg = &req->misc.init_in;
912 
913 	arg->major = FUSE_KERNEL_VERSION;
914 	arg->minor = FUSE_KERNEL_MINOR_VERSION;
915 	arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
916 	arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |
917 		FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES | FUSE_DONT_MASK |
918 		FUSE_SPLICE_WRITE | FUSE_SPLICE_MOVE | FUSE_SPLICE_READ |
919 		FUSE_FLOCK_LOCKS | FUSE_IOCTL_DIR | FUSE_AUTO_INVAL_DATA |
920 		FUSE_DO_READDIRPLUS | FUSE_READDIRPLUS_AUTO | FUSE_ASYNC_DIO |
921 		FUSE_WRITEBACK_CACHE;
922 	req->in.h.opcode = FUSE_INIT;
923 	req->in.numargs = 1;
924 	req->in.args[0].size = sizeof(*arg);
925 	req->in.args[0].value = arg;
926 	req->out.numargs = 1;
927 	/* Variable length argument used for backward compatibility
928 	   with interface version < 7.5.  Rest of init_out is zeroed
929 	   by do_get_request(), so a short reply is not a problem */
930 	req->out.argvar = 1;
931 	req->out.args[0].size = sizeof(struct fuse_init_out);
932 	req->out.args[0].value = &req->misc.init_out;
933 	req->end = process_init_reply;
934 	fuse_request_send_background(fc, req);
935 }
936 
937 static void fuse_free_conn(struct fuse_conn *fc)
938 {
939 	kfree_rcu(fc, rcu);
940 }
941 
942 static int fuse_bdi_init(struct fuse_conn *fc, struct super_block *sb)
943 {
944 	int err;
945 
946 	fc->bdi.name = "fuse";
947 	fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
948 	/* fuse does it's own writeback accounting */
949 	fc->bdi.capabilities = BDI_CAP_NO_ACCT_WB | BDI_CAP_STRICTLIMIT;
950 
951 	err = bdi_init(&fc->bdi);
952 	if (err)
953 		return err;
954 
955 	fc->bdi_initialized = 1;
956 
957 	if (sb->s_bdev) {
958 		err =  bdi_register(&fc->bdi, NULL, "%u:%u-fuseblk",
959 				    MAJOR(fc->dev), MINOR(fc->dev));
960 	} else {
961 		err = bdi_register_dev(&fc->bdi, fc->dev);
962 	}
963 
964 	if (err)
965 		return err;
966 
967 	/*
968 	 * For a single fuse filesystem use max 1% of dirty +
969 	 * writeback threshold.
970 	 *
971 	 * This gives about 1M of write buffer for memory maps on a
972 	 * machine with 1G and 10% dirty_ratio, which should be more
973 	 * than enough.
974 	 *
975 	 * Privileged users can raise it by writing to
976 	 *
977 	 *    /sys/class/bdi/<bdi>/max_ratio
978 	 */
979 	bdi_set_max_ratio(&fc->bdi, 1);
980 
981 	return 0;
982 }
983 
984 static int fuse_fill_super(struct super_block *sb, void *data, int silent)
985 {
986 	struct fuse_conn *fc;
987 	struct inode *root;
988 	struct fuse_mount_data d;
989 	struct file *file;
990 	struct dentry *root_dentry;
991 	struct fuse_req *init_req;
992 	int err;
993 	int is_bdev = sb->s_bdev != NULL;
994 
995 	err = -EINVAL;
996 	if (sb->s_flags & MS_MANDLOCK)
997 		goto err;
998 
999 	sb->s_flags &= ~MS_NOSEC;
1000 
1001 	if (!parse_fuse_opt((char *) data, &d, is_bdev))
1002 		goto err;
1003 
1004 	if (is_bdev) {
1005 #ifdef CONFIG_BLOCK
1006 		err = -EINVAL;
1007 		if (!sb_set_blocksize(sb, d.blksize))
1008 			goto err;
1009 #endif
1010 	} else {
1011 		sb->s_blocksize = PAGE_CACHE_SIZE;
1012 		sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
1013 	}
1014 	sb->s_magic = FUSE_SUPER_MAGIC;
1015 	sb->s_op = &fuse_super_operations;
1016 	sb->s_maxbytes = MAX_LFS_FILESIZE;
1017 	sb->s_time_gran = 1;
1018 	sb->s_export_op = &fuse_export_operations;
1019 
1020 	file = fget(d.fd);
1021 	err = -EINVAL;
1022 	if (!file)
1023 		goto err;
1024 
1025 	if ((file->f_op != &fuse_dev_operations) ||
1026 	    (file->f_cred->user_ns != &init_user_ns))
1027 		goto err_fput;
1028 
1029 	fc = kmalloc(sizeof(*fc), GFP_KERNEL);
1030 	err = -ENOMEM;
1031 	if (!fc)
1032 		goto err_fput;
1033 
1034 	fuse_conn_init(fc);
1035 
1036 	fc->dev = sb->s_dev;
1037 	fc->sb = sb;
1038 	err = fuse_bdi_init(fc, sb);
1039 	if (err)
1040 		goto err_put_conn;
1041 
1042 	sb->s_bdi = &fc->bdi;
1043 
1044 	/* Handle umasking inside the fuse code */
1045 	if (sb->s_flags & MS_POSIXACL)
1046 		fc->dont_mask = 1;
1047 	sb->s_flags |= MS_POSIXACL;
1048 
1049 	fc->release = fuse_free_conn;
1050 	fc->flags = d.flags;
1051 	fc->user_id = d.user_id;
1052 	fc->group_id = d.group_id;
1053 	fc->max_read = max_t(unsigned, 4096, d.max_read);
1054 
1055 	/* Used by get_root_inode() */
1056 	sb->s_fs_info = fc;
1057 
1058 	err = -ENOMEM;
1059 	root = fuse_get_root_inode(sb, d.rootmode);
1060 	root_dentry = d_make_root(root);
1061 	if (!root_dentry)
1062 		goto err_put_conn;
1063 	/* only now - we want root dentry with NULL ->d_op */
1064 	sb->s_d_op = &fuse_dentry_operations;
1065 
1066 	init_req = fuse_request_alloc(0);
1067 	if (!init_req)
1068 		goto err_put_root;
1069 	init_req->background = 1;
1070 
1071 	if (is_bdev) {
1072 		fc->destroy_req = fuse_request_alloc(0);
1073 		if (!fc->destroy_req)
1074 			goto err_free_init_req;
1075 	}
1076 
1077 	mutex_lock(&fuse_mutex);
1078 	err = -EINVAL;
1079 	if (file->private_data)
1080 		goto err_unlock;
1081 
1082 	err = fuse_ctl_add_conn(fc);
1083 	if (err)
1084 		goto err_unlock;
1085 
1086 	list_add_tail(&fc->entry, &fuse_conn_list);
1087 	sb->s_root = root_dentry;
1088 	fc->connected = 1;
1089 	file->private_data = fuse_conn_get(fc);
1090 	mutex_unlock(&fuse_mutex);
1091 	/*
1092 	 * atomic_dec_and_test() in fput() provides the necessary
1093 	 * memory barrier for file->private_data to be visible on all
1094 	 * CPUs after this
1095 	 */
1096 	fput(file);
1097 
1098 	fuse_send_init(fc, init_req);
1099 
1100 	return 0;
1101 
1102  err_unlock:
1103 	mutex_unlock(&fuse_mutex);
1104  err_free_init_req:
1105 	fuse_request_free(init_req);
1106  err_put_root:
1107 	dput(root_dentry);
1108  err_put_conn:
1109 	fuse_bdi_destroy(fc);
1110 	fuse_conn_put(fc);
1111  err_fput:
1112 	fput(file);
1113  err:
1114 	return err;
1115 }
1116 
1117 static struct dentry *fuse_mount(struct file_system_type *fs_type,
1118 		       int flags, const char *dev_name,
1119 		       void *raw_data)
1120 {
1121 	return mount_nodev(fs_type, flags, raw_data, fuse_fill_super);
1122 }
1123 
1124 static void fuse_kill_sb_anon(struct super_block *sb)
1125 {
1126 	struct fuse_conn *fc = get_fuse_conn_super(sb);
1127 
1128 	if (fc) {
1129 		down_write(&fc->killsb);
1130 		fc->sb = NULL;
1131 		up_write(&fc->killsb);
1132 	}
1133 
1134 	kill_anon_super(sb);
1135 }
1136 
1137 static struct file_system_type fuse_fs_type = {
1138 	.owner		= THIS_MODULE,
1139 	.name		= "fuse",
1140 	.fs_flags	= FS_HAS_SUBTYPE,
1141 	.mount		= fuse_mount,
1142 	.kill_sb	= fuse_kill_sb_anon,
1143 };
1144 MODULE_ALIAS_FS("fuse");
1145 
1146 #ifdef CONFIG_BLOCK
1147 static struct dentry *fuse_mount_blk(struct file_system_type *fs_type,
1148 			   int flags, const char *dev_name,
1149 			   void *raw_data)
1150 {
1151 	return mount_bdev(fs_type, flags, dev_name, raw_data, fuse_fill_super);
1152 }
1153 
1154 static void fuse_kill_sb_blk(struct super_block *sb)
1155 {
1156 	struct fuse_conn *fc = get_fuse_conn_super(sb);
1157 
1158 	if (fc) {
1159 		down_write(&fc->killsb);
1160 		fc->sb = NULL;
1161 		up_write(&fc->killsb);
1162 	}
1163 
1164 	kill_block_super(sb);
1165 }
1166 
1167 static struct file_system_type fuseblk_fs_type = {
1168 	.owner		= THIS_MODULE,
1169 	.name		= "fuseblk",
1170 	.mount		= fuse_mount_blk,
1171 	.kill_sb	= fuse_kill_sb_blk,
1172 	.fs_flags	= FS_REQUIRES_DEV | FS_HAS_SUBTYPE,
1173 };
1174 MODULE_ALIAS_FS("fuseblk");
1175 
1176 static inline int register_fuseblk(void)
1177 {
1178 	return register_filesystem(&fuseblk_fs_type);
1179 }
1180 
1181 static inline void unregister_fuseblk(void)
1182 {
1183 	unregister_filesystem(&fuseblk_fs_type);
1184 }
1185 #else
1186 static inline int register_fuseblk(void)
1187 {
1188 	return 0;
1189 }
1190 
1191 static inline void unregister_fuseblk(void)
1192 {
1193 }
1194 #endif
1195 
1196 static void fuse_inode_init_once(void *foo)
1197 {
1198 	struct inode *inode = foo;
1199 
1200 	inode_init_once(inode);
1201 }
1202 
1203 static int __init fuse_fs_init(void)
1204 {
1205 	int err;
1206 
1207 	fuse_inode_cachep = kmem_cache_create("fuse_inode",
1208 					      sizeof(struct fuse_inode),
1209 					      0, SLAB_HWCACHE_ALIGN,
1210 					      fuse_inode_init_once);
1211 	err = -ENOMEM;
1212 	if (!fuse_inode_cachep)
1213 		goto out;
1214 
1215 	err = register_fuseblk();
1216 	if (err)
1217 		goto out2;
1218 
1219 	err = register_filesystem(&fuse_fs_type);
1220 	if (err)
1221 		goto out3;
1222 
1223 	return 0;
1224 
1225  out3:
1226 	unregister_fuseblk();
1227  out2:
1228 	kmem_cache_destroy(fuse_inode_cachep);
1229  out:
1230 	return err;
1231 }
1232 
1233 static void fuse_fs_cleanup(void)
1234 {
1235 	unregister_filesystem(&fuse_fs_type);
1236 	unregister_fuseblk();
1237 
1238 	/*
1239 	 * Make sure all delayed rcu free inodes are flushed before we
1240 	 * destroy cache.
1241 	 */
1242 	rcu_barrier();
1243 	kmem_cache_destroy(fuse_inode_cachep);
1244 }
1245 
1246 static struct kobject *fuse_kobj;
1247 static struct kobject *connections_kobj;
1248 
1249 static int fuse_sysfs_init(void)
1250 {
1251 	int err;
1252 
1253 	fuse_kobj = kobject_create_and_add("fuse", fs_kobj);
1254 	if (!fuse_kobj) {
1255 		err = -ENOMEM;
1256 		goto out_err;
1257 	}
1258 
1259 	connections_kobj = kobject_create_and_add("connections", fuse_kobj);
1260 	if (!connections_kobj) {
1261 		err = -ENOMEM;
1262 		goto out_fuse_unregister;
1263 	}
1264 
1265 	return 0;
1266 
1267  out_fuse_unregister:
1268 	kobject_put(fuse_kobj);
1269  out_err:
1270 	return err;
1271 }
1272 
1273 static void fuse_sysfs_cleanup(void)
1274 {
1275 	kobject_put(connections_kobj);
1276 	kobject_put(fuse_kobj);
1277 }
1278 
1279 static int __init fuse_init(void)
1280 {
1281 	int res;
1282 
1283 	printk(KERN_INFO "fuse init (API version %i.%i)\n",
1284 	       FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
1285 
1286 	INIT_LIST_HEAD(&fuse_conn_list);
1287 	res = fuse_fs_init();
1288 	if (res)
1289 		goto err;
1290 
1291 	res = fuse_dev_init();
1292 	if (res)
1293 		goto err_fs_cleanup;
1294 
1295 	res = fuse_sysfs_init();
1296 	if (res)
1297 		goto err_dev_cleanup;
1298 
1299 	res = fuse_ctl_init();
1300 	if (res)
1301 		goto err_sysfs_cleanup;
1302 
1303 	sanitize_global_limit(&max_user_bgreq);
1304 	sanitize_global_limit(&max_user_congthresh);
1305 
1306 	return 0;
1307 
1308  err_sysfs_cleanup:
1309 	fuse_sysfs_cleanup();
1310  err_dev_cleanup:
1311 	fuse_dev_cleanup();
1312  err_fs_cleanup:
1313 	fuse_fs_cleanup();
1314  err:
1315 	return res;
1316 }
1317 
1318 static void __exit fuse_exit(void)
1319 {
1320 	printk(KERN_DEBUG "fuse exit\n");
1321 
1322 	fuse_ctl_cleanup();
1323 	fuse_sysfs_cleanup();
1324 	fuse_fs_cleanup();
1325 	fuse_dev_cleanup();
1326 }
1327 
1328 module_init(fuse_init);
1329 module_exit(fuse_exit);
1330