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	#include "fuse_dev_i.h"
11	#include "dev_uring_i.h"
12
13	#include <linux/dax.h>
14	#include <linux/pagemap.h>
15	#include <linux/slab.h>
16	#include <linux/file.h>
17	#include <linux/seq_file.h>
18	#include <linux/init.h>
19	#include <linux/module.h>
20	#include <linux/moduleparam.h>
21	#include <linux/fs_context.h>
22	#include <linux/fs_parser.h>
23	#include <linux/statfs.h>
24	#include <linux/random.h>
25	#include <linux/sched.h>
26	#include <linux/exportfs.h>
27	#include <linux/posix_acl.h>
28	#include <linux/pid_namespace.h>
29	#include <uapi/linux/magic.h>
30
31	MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
32	MODULE_DESCRIPTION("Filesystem in Userspace");
33	MODULE_LICENSE("GPL");
34
35	static struct kmem_cache *fuse_inode_cachep;
36	struct list_head fuse_conn_list;
37	DEFINE_MUTEX(fuse_mutex);
38	DECLARE_WAIT_QUEUE_HEAD(fuse_dev_waitq);
39
40	static int set_global_limit(const char *val, const struct kernel_param *kp);
41
42	unsigned int fuse_max_pages_limit = 256;
43	/* default is no timeout */
44	unsigned int fuse_default_req_timeout;
45	unsigned int fuse_max_req_timeout;
46
47	unsigned int max_user_bgreq;
48	module_param_call(max_user_bgreq, set_global_limit, param_get_uint,
49	&max_user_bgreq, 0644);
50	__MODULE_PARM_TYPE(max_user_bgreq, "uint");
51	MODULE_PARM_DESC(max_user_bgreq,
52	"Global limit for the maximum number of backgrounded requests an "
53	"unprivileged user can set");
54
55	unsigned int max_user_congthresh;
56	module_param_call(max_user_congthresh, set_global_limit, param_get_uint,
57	&max_user_congthresh, 0644);
58	__MODULE_PARM_TYPE(max_user_congthresh, "uint");
59	MODULE_PARM_DESC(max_user_congthresh,
60	"Global limit for the maximum congestion threshold an "
61	"unprivileged user can set");
62
63	#define FUSE_DEFAULT_BLKSIZE 512
64
65	/** Maximum number of outstanding background requests */
66	#define FUSE_DEFAULT_MAX_BACKGROUND 12
67
68	/** Congestion starts at 75% of maximum */
69	#define FUSE_DEFAULT_CONGESTION_THRESHOLD (FUSE_DEFAULT_MAX_BACKGROUND * 3 / 4)
70
71	#ifdef CONFIG_BLOCK
72	static struct file_system_type fuseblk_fs_type;
73	#endif
74
75	struct fuse_forget_link *fuse_alloc_forget(void)
76	{
77	return kzalloc(sizeof(struct fuse_forget_link), GFP_KERNEL_ACCOUNT);
78	}
79
80	static struct fuse_submount_lookup *fuse_alloc_submount_lookup(void)
81	{
82	struct fuse_submount_lookup *sl;
83
84	sl = kzalloc(sizeof(struct fuse_submount_lookup), GFP_KERNEL_ACCOUNT);
85	if (!sl)
86	return NULL;
87	sl->forget = fuse_alloc_forget();
88	if (!sl->forget)
89	goto out_free;
90
91	return sl;
92
93	out_free:
94	kfree(objp: sl);
95	return NULL;
96	}
97
98	static struct inode *fuse_alloc_inode(struct super_block *sb)
99	{
100	struct fuse_inode *fi;
101
102	fi = alloc_inode_sb(sb, fuse_inode_cachep, GFP_KERNEL);
103	if (!fi)
104	return NULL;
105
106	/* Initialize private data (i.e. everything except fi->inode) */
107	BUILD_BUG_ON(offsetof(struct fuse_inode, inode) != 0);
108	memset((void *) fi + sizeof(fi->inode), 0, sizeof(*fi) - sizeof(fi->inode));
109
110	fi->inval_mask = ~0;
111	mutex_init(&fi->mutex);
112	spin_lock_init(&fi->lock);
113	fi->forget = fuse_alloc_forget();
114	if (!fi->forget)
115	goto out_free;
116
117	if (IS_ENABLED(CONFIG_FUSE_DAX) && !fuse_dax_inode_alloc(sb, fi))
118	goto out_free_forget;
119
120	if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
121	fuse_inode_backing_set(fi, NULL);
122
123	return &fi->inode;
124
125	out_free_forget:
126	kfree(objp: fi->forget);
127	out_free:
128	kmem_cache_free(s: fuse_inode_cachep, objp: fi);
129	return NULL;
130	}
131
132	static void fuse_free_inode(struct inode *inode)
133	{
134	struct fuse_inode *fi = get_fuse_inode(inode);
135
136	mutex_destroy(lock: &fi->mutex);
137	kfree(objp: fi->forget);
138	#ifdef CONFIG_FUSE_DAX
139	kfree(objp: fi->dax);
140	#endif
141	if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
142	fuse_backing_put(fb: fuse_inode_backing(fi));
143
144	kmem_cache_free(s: fuse_inode_cachep, objp: fi);
145	}
146
147	static void fuse_cleanup_submount_lookup(struct fuse_conn *fc,
148	struct fuse_submount_lookup *sl)
149	{
150	if (!refcount_dec_and_test(r: &sl->count))
151	return;
152
153	fuse_queue_forget(fc, forget: sl->forget, nodeid: sl->nodeid, nlookup: 1);
154	sl->forget = NULL;
155	kfree(objp: sl);
156	}
157
158	static void fuse_evict_inode(struct inode *inode)
159	{
160	struct fuse_inode *fi = get_fuse_inode(inode);
161
162	/* Will write inode on close/munmap and in all other dirtiers */
163	WARN_ON(inode_state_read_once(inode) & I_DIRTY_INODE);
164
165	if (FUSE_IS_DAX(inode))
166	dax_break_layout_final(inode);
167
168	truncate_inode_pages_final(mapping: &inode->i_data);
169	clear_inode(inode);
170	if (inode->i_sb->s_flags & SB_ACTIVE) {
171	struct fuse_conn *fc = get_fuse_conn(inode);
172
173	if (FUSE_IS_DAX(inode))
174	fuse_dax_inode_cleanup(inode);
175	if (fi->nlookup) {
176	fuse_queue_forget(fc, forget: fi->forget, nodeid: fi->nodeid,
177	nlookup: fi->nlookup);
178	fi->forget = NULL;
179	}
180
181	if (fi->submount_lookup) {
182	fuse_cleanup_submount_lookup(fc, sl: fi->submount_lookup);
183	fi->submount_lookup = NULL;
184	}
185	/*
186	* Evict of non-deleted inode may race with outstanding
187	* LOOKUP/READDIRPLUS requests and result in inconsistency when
188	* the request finishes. Deal with that here by bumping a
189	* counter that can be compared to the starting value.
190	*/
191	if (inode->i_nlink > 0)
192	atomic64_inc(v: &fc->evict_ctr);
193	}
194	if (S_ISREG(inode->i_mode) && !fuse_is_bad(inode)) {
195	WARN_ON(fi->iocachectr != 0);
196	WARN_ON(!list_empty(&fi->write_files));
197	WARN_ON(!list_empty(&fi->queued_writes));
198	}
199	}
200
201	static int fuse_reconfigure(struct fs_context *fsc)
202	{
203	struct super_block *sb = fsc->root->d_sb;
204
205	sync_filesystem(sb);
206	if (fsc->sb_flags & SB_MANDLOCK)
207	return -EINVAL;
208
209	return 0;
210	}
211
212	/*
213	* ino_t is 32-bits on 32-bit arch. We have to squash the 64-bit value down
214	* so that it will fit.
215	*/
216	static ino_t fuse_squash_ino(u64 ino64)
217	{
218	ino_t ino = (ino_t) ino64;
219	if (sizeof(ino_t) < sizeof(u64))
220	ino ^= ino64 >> (sizeof(u64) - sizeof(ino_t)) * 8;
221	return ino;
222	}
223
224	void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
225	struct fuse_statx *sx,
226	u64 attr_valid, u32 cache_mask,
227	u64 evict_ctr)
228	{
229	struct fuse_conn *fc = get_fuse_conn(inode);
230	struct fuse_inode *fi = get_fuse_inode(inode);
231
232	lockdep_assert_held(&fi->lock);
233
234	/*
235	* Clear basic stats from invalid mask.
236	*
237	* Don't do this if this is coming from a fuse_iget() call and there
238	* might have been a racing evict which would've invalidated the result
239	* if the attr_version would've been preserved.
240	*
241	* !evict_ctr -> this is create
242	* fi->attr_version != 0 -> this is not a new inode
243	* evict_ctr == fuse_get_evict_ctr() -> no evicts while during request
244	*/
245	if (!evict_ctr || fi->attr_version || evict_ctr == fuse_get_evict_ctr(fc))
246	set_mask_bits(&fi->inval_mask, STATX_BASIC_STATS, 0);
247
248	fi->attr_version = atomic64_inc_return(v: &fc->attr_version);
249	fi->i_time = attr_valid;
250
251	inode->i_ino = fuse_squash_ino(ino64: attr->ino);
252	inode->i_mode = (inode->i_mode & S_IFMT) | (attr->mode & 07777);
253	set_nlink(inode, nlink: attr->nlink);
254	inode->i_uid = make_kuid(from: fc->user_ns, uid: attr->uid);
255	inode->i_gid = make_kgid(from: fc->user_ns, gid: attr->gid);
256	inode->i_blocks = attr->blocks;
257
258	/* Sanitize nsecs */
259	attr->atimensec = min_t(u32, attr->atimensec, NSEC_PER_SEC - 1);
260	attr->mtimensec = min_t(u32, attr->mtimensec, NSEC_PER_SEC - 1);
261	attr->ctimensec = min_t(u32, attr->ctimensec, NSEC_PER_SEC - 1);
262
263	inode_set_atime(inode, sec: attr->atime, nsec: attr->atimensec);
264	/* mtime from server may be stale due to local buffered write */
265	if (!(cache_mask & STATX_MTIME)) {
266	inode_set_mtime(inode, sec: attr->mtime, nsec: attr->mtimensec);
267	}
268	if (!(cache_mask & STATX_CTIME)) {
269	inode_set_ctime(inode, sec: attr->ctime, nsec: attr->ctimensec);
270	}
271	if (sx) {
272	/* Sanitize nsecs */
273	sx->btime.tv_nsec =
274	min_t(u32, sx->btime.tv_nsec, NSEC_PER_SEC - 1);
275
276	/*
277	* Btime has been queried, cache is valid (whether or not btime
278	* is available or not) so clear STATX_BTIME from inval_mask.
279	*
280	* Availability of the btime attribute is indicated in
281	* FUSE_I_BTIME
282	*/
283	set_mask_bits(&fi->inval_mask, STATX_BTIME, 0);
284	if (sx->mask & STATX_BTIME) {
285	set_bit(nr: FUSE_I_BTIME, addr: &fi->state);
286	fi->i_btime.tv_sec = sx->btime.tv_sec;
287	fi->i_btime.tv_nsec = sx->btime.tv_nsec;
288	}
289	}
290
291	if (attr->blksize)
292	fi->cached_i_blkbits = ilog2(attr->blksize);
293	else
294	fi->cached_i_blkbits = inode->i_sb->s_blocksize_bits;
295
296	/*
297	* Don't set the sticky bit in i_mode, unless we want the VFS
298	* to check permissions. This prevents failures due to the
299	* check in may_delete().
300	*/
301	fi->orig_i_mode = inode->i_mode;
302	if (!fc->default_permissions)
303	inode->i_mode &= ~S_ISVTX;
304
305	fi->orig_ino = attr->ino;
306
307	/*
308	* We are refreshing inode data and it is possible that another
309	* client set suid/sgid or security.capability xattr. So clear
310	* S_NOSEC. Ideally, we could have cleared it only if suid/sgid
311	* was set or if security.capability xattr was set. But we don't
312	* know if security.capability has been set or not. So clear it
313	* anyway. Its less efficient but should be safe.
314	*/
315	inode->i_flags &= ~S_NOSEC;
316	}
317
318	u32 fuse_get_cache_mask(struct inode *inode)
319	{
320	struct fuse_conn *fc = get_fuse_conn(inode);
321
322	if (!fc->writeback_cache || !S_ISREG(inode->i_mode))
323	return 0;
324
325	return STATX_MTIME | STATX_CTIME | STATX_SIZE;
326	}
327
328	static void fuse_change_attributes_i(struct inode *inode, struct fuse_attr *attr,
329	struct fuse_statx *sx, u64 attr_valid,
330	u64 attr_version, u64 evict_ctr)
331	{
332	struct fuse_conn *fc = get_fuse_conn(inode);
333	struct fuse_inode *fi = get_fuse_inode(inode);
334	u32 cache_mask;
335	loff_t oldsize;
336	struct timespec64 old_mtime;
337
338	spin_lock(lock: &fi->lock);
339	/*
340	* In case of writeback_cache enabled, writes update mtime, ctime and
341	* may update i_size. In these cases trust the cached value in the
342	* inode.
343	*/
344	cache_mask = fuse_get_cache_mask(inode);
345	if (cache_mask & STATX_SIZE)
346	attr->size = i_size_read(inode);
347
348	if (cache_mask & STATX_MTIME) {
349	attr->mtime = inode_get_mtime_sec(inode);
350	attr->mtimensec = inode_get_mtime_nsec(inode);
351	}
352	if (cache_mask & STATX_CTIME) {
353	attr->ctime = inode_get_ctime_sec(inode);
354	attr->ctimensec = inode_get_ctime_nsec(inode);
355	}
356
357	if ((attr_version != 0 && fi->attr_version > attr_version) ||
358	test_bit(FUSE_I_SIZE_UNSTABLE, &fi->state)) {
359	spin_unlock(lock: &fi->lock);
360	return;
361	}
362
363	old_mtime = inode_get_mtime(inode);
364	fuse_change_attributes_common(inode, attr, sx, attr_valid, cache_mask,
365	evict_ctr);
366
367	oldsize = inode->i_size;
368	/*
369	* In case of writeback_cache enabled, the cached writes beyond EOF
370	* extend local i_size without keeping userspace server in sync. So,
371	* attr->size coming from server can be stale. We cannot trust it.
372	*/
373	if (!(cache_mask & STATX_SIZE))
374	i_size_write(inode, i_size: attr->size);
375	spin_unlock(lock: &fi->lock);
376
377	if (!cache_mask && S_ISREG(inode->i_mode)) {
378	bool inval = false;
379
380	if (oldsize != attr->size) {
381	truncate_pagecache(inode, new: attr->size);
382	if (!fc->explicit_inval_data)
383	inval = true;
384	} else if (fc->auto_inval_data) {
385	struct timespec64 new_mtime = {
386	.tv_sec = attr->mtime,
387	.tv_nsec = attr->mtimensec,
388	};
389
390	/*
391	* Auto inval mode also checks and invalidates if mtime
392	* has changed.
393	*/
394	if (!timespec64_equal(a: &old_mtime, b: &new_mtime))
395	inval = true;
396	}
397
398	if (inval)
399	invalidate_inode_pages2(mapping: inode->i_mapping);
400	}
401
402	if (IS_ENABLED(CONFIG_FUSE_DAX))
403	fuse_dax_dontcache(inode, flags: attr->flags);
404	}
405
406	void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
407	struct fuse_statx *sx, u64 attr_valid,
408	u64 attr_version)
409	{
410	fuse_change_attributes_i(inode, attr, sx, attr_valid, attr_version, evict_ctr: 0);
411	}
412
413	static void fuse_init_submount_lookup(struct fuse_submount_lookup *sl,
414	u64 nodeid)
415	{
416	sl->nodeid = nodeid;
417	refcount_set(r: &sl->count, n: 1);
418	}
419
420	static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr,
421	struct fuse_conn *fc)
422	{
423	inode->i_mode = attr->mode & S_IFMT;
424	inode->i_size = attr->size;
425	inode_set_mtime(inode, sec: attr->mtime, nsec: attr->mtimensec);
426	inode_set_ctime(inode, sec: attr->ctime, nsec: attr->ctimensec);
427	if (S_ISREG(inode->i_mode)) {
428	fuse_init_common(inode);
429	fuse_init_file_inode(inode, flags: attr->flags);
430	} else if (S_ISDIR(inode->i_mode))
431	fuse_init_dir(inode);
432	else if (S_ISLNK(inode->i_mode))
433	fuse_init_symlink(inode);
434	else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
435	S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
436	fuse_init_common(inode);
437	init_special_inode(inode, inode->i_mode,
438	new_decode_dev(dev: attr->rdev));
439	} else
440	BUG();
441	/*
442	* Ensure that we don't cache acls for daemons without FUSE_POSIX_ACL
443	* so they see the exact same behavior as before.
444	*/
445	if (!fc->posix_acl)
446	inode->i_acl = inode->i_default_acl = ACL_DONT_CACHE;
447	}
448
449	static int fuse_inode_eq(struct inode *inode, void *_nodeidp)
450	{
451	u64 nodeid = *(u64 *) _nodeidp;
452	if (get_node_id(inode) == nodeid)
453	return 1;
454	else
455	return 0;
456	}
457
458	static int fuse_inode_set(struct inode *inode, void *_nodeidp)
459	{
460	u64 nodeid = *(u64 *) _nodeidp;
461	get_fuse_inode(inode)->nodeid = nodeid;
462	return 0;
463	}
464
465	struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
466	int generation, struct fuse_attr *attr,
467	u64 attr_valid, u64 attr_version,
468	u64 evict_ctr)
469	{
470	struct inode *inode;
471	struct fuse_inode *fi;
472	struct fuse_conn *fc = get_fuse_conn_super(sb);
473
474	/*
475	* Auto mount points get their node id from the submount root, which is
476	* not a unique identifier within this filesystem.
477	*
478	* To avoid conflicts, do not place submount points into the inode hash
479	* table.
480	*/
481	if (fc->auto_submounts && (attr->flags & FUSE_ATTR_SUBMOUNT) &&
482	S_ISDIR(attr->mode)) {
483	struct fuse_inode *fi;
484
485	inode = new_inode(sb);
486	if (!inode)
487	return NULL;
488
489	fuse_init_inode(inode, attr, fc);
490	fi = get_fuse_inode(inode);
491	fi->nodeid = nodeid;
492	fi->submount_lookup = fuse_alloc_submount_lookup();
493	if (!fi->submount_lookup) {
494	iput(inode);
495	return NULL;
496	}
497	/* Sets nlookup = 1 on fi->submount_lookup->nlookup */
498	fuse_init_submount_lookup(sl: fi->submount_lookup, nodeid);
499	inode->i_flags |= S_AUTOMOUNT;
500	goto done;
501	}
502
503	retry:
504	inode = iget5_locked(sb, nodeid, test: fuse_inode_eq, set: fuse_inode_set, &nodeid);
505	if (!inode)
506	return NULL;
507
508	if ((inode_state_read_once(inode) & I_NEW)) {
509	inode->i_flags |= S_NOATIME;
510	if (!fc->writeback_cache || !S_ISREG(attr->mode))
511	inode->i_flags |= S_NOCMTIME;
512	inode->i_generation = generation;
513	fuse_init_inode(inode, attr, fc);
514	unlock_new_inode(inode);
515	} else if (fuse_stale_inode(inode, generation, attr)) {
516	/* nodeid was reused, any I/O on the old inode should fail */
517	fuse_make_bad(inode);
518	if (inode != d_inode(dentry: sb->s_root)) {
519	remove_inode_hash(inode);
520	iput(inode);
521	goto retry;
522	}
523	}
524	fi = get_fuse_inode(inode);
525	spin_lock(lock: &fi->lock);
526	fi->nlookup++;
527	spin_unlock(lock: &fi->lock);
528	done:
529	fuse_change_attributes_i(inode, attr, NULL, attr_valid, attr_version,
530	evict_ctr);
531	return inode;
532	}
533
534	struct inode *fuse_ilookup(struct fuse_conn *fc, u64 nodeid,
535	struct fuse_mount **fm)
536	{
537	struct fuse_mount *fm_iter;
538	struct inode *inode;
539
540	WARN_ON(!rwsem_is_locked(&fc->killsb));
541	list_for_each_entry(fm_iter, &fc->mounts, fc_entry) {
542	if (!fm_iter->sb)
543	continue;
544
545	inode = ilookup5(sb: fm_iter->sb, hashval: nodeid, test: fuse_inode_eq, data: &nodeid);
546	if (inode) {
547	if (fm)
548	*fm = fm_iter;
549	return inode;
550	}
551	}
552
553	return NULL;
554	}
555
556	int fuse_reverse_inval_inode(struct fuse_conn *fc, u64 nodeid,
557	loff_t offset, loff_t len)
558	{
559	struct fuse_inode *fi;
560	struct inode *inode;
561	pgoff_t pg_start;
562	pgoff_t pg_end;
563
564	inode = fuse_ilookup(fc, nodeid, NULL);
565	if (!inode)
566	return -ENOENT;
567
568	fi = get_fuse_inode(inode);
569	spin_lock(lock: &fi->lock);
570	fi->attr_version = atomic64_inc_return(v: &fc->attr_version);
571	spin_unlock(lock: &fi->lock);
572
573	fuse_invalidate_attr(inode);
574	forget_all_cached_acls(inode);
575	if (offset >= 0) {
576	pg_start = offset >> PAGE_SHIFT;
577	if (len <= 0)
578	pg_end = -1;
579	else
580	pg_end = (offset + len - 1) >> PAGE_SHIFT;
581	invalidate_inode_pages2_range(mapping: inode->i_mapping,
582	start: pg_start, end: pg_end);
583	}
584	iput(inode);
585	return 0;
586	}
587
588	void fuse_try_prune_one_inode(struct fuse_conn *fc, u64 nodeid)
589	{
590	struct inode *inode;
591
592	inode = fuse_ilookup(fc, nodeid, NULL);
593	if (!inode)
594	return;
595	d_prune_aliases(inode);
596	iput(inode);
597	}
598
599	bool fuse_lock_inode(struct inode *inode)
600	{
601	bool locked = false;
602
603	if (!get_fuse_conn(inode)->parallel_dirops) {
604	mutex_lock(&get_fuse_inode(inode)->mutex);
605	locked = true;
606	}
607
608	return locked;
609	}
610
611	void fuse_unlock_inode(struct inode *inode, bool locked)
612	{
613	if (locked)
614	mutex_unlock(lock: &get_fuse_inode(inode)->mutex);
615	}
616
617	static void fuse_umount_begin(struct super_block *sb)
618	{
619	struct fuse_conn *fc = get_fuse_conn_super(sb);
620
621	if (fc->no_force_umount)
622	return;
623
624	fuse_abort_conn(fc);
625
626	// Only retire block-device-based superblocks.
627	if (sb->s_bdev != NULL)
628	retire_super(sb);
629	}
630
631	static void fuse_send_destroy(struct fuse_mount *fm)
632	{
633	if (fm->fc->conn_init) {
634	FUSE_ARGS(args);
635
636	args.opcode = FUSE_DESTROY;
637	args.force = true;
638	args.nocreds = true;
639	fuse_simple_request(fm, args: &args);
640	}
641	}
642
643	static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
644	{
645	stbuf->f_type = FUSE_SUPER_MAGIC;
646	stbuf->f_bsize = attr->bsize;
647	stbuf->f_frsize = attr->frsize;
648	stbuf->f_blocks = attr->blocks;
649	stbuf->f_bfree = attr->bfree;
650	stbuf->f_bavail = attr->bavail;
651	stbuf->f_files = attr->files;
652	stbuf->f_ffree = attr->ffree;
653	stbuf->f_namelen = attr->namelen;
654	/* fsid is left zero */
655	}
656
657	static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)
658	{
659	struct super_block *sb = dentry->d_sb;
660	struct fuse_mount *fm = get_fuse_mount_super(sb);
661	FUSE_ARGS(args);
662	struct fuse_statfs_out outarg;
663	int err;
664
665	if (!fuse_allow_current_process(fc: fm->fc)) {
666	buf->f_type = FUSE_SUPER_MAGIC;
667	return 0;
668	}
669
670	memset(&outarg, 0, sizeof(outarg));
671	args.in_numargs = 0;
672	args.opcode = FUSE_STATFS;
673	args.nodeid = get_node_id(inode: d_inode(dentry));
674	args.out_numargs = 1;
675	args.out_args[0].size = sizeof(outarg);
676	args.out_args[0].value = &outarg;
677	err = fuse_simple_request(fm, args: &args);
678	if (!err)
679	convert_fuse_statfs(stbuf: buf, attr: &outarg.st);
680	return err;
681	}
682
683	static struct fuse_sync_bucket *fuse_sync_bucket_alloc(void)
684	{
685	struct fuse_sync_bucket *bucket;
686
687	bucket = kzalloc(sizeof(*bucket), GFP_KERNEL | __GFP_NOFAIL);
688	if (bucket) {
689	init_waitqueue_head(&bucket->waitq);
690	/* Initial active count */
691	atomic_set(v: &bucket->count, i: 1);
692	}
693	return bucket;
694	}
695
696	static void fuse_sync_fs_writes(struct fuse_conn *fc)
697	{
698	struct fuse_sync_bucket *bucket, *new_bucket;
699	int count;
700
701	new_bucket = fuse_sync_bucket_alloc();
702	spin_lock(lock: &fc->lock);
703	bucket = rcu_dereference_protected(fc->curr_bucket, 1);
704	count = atomic_read(v: &bucket->count);
705	WARN_ON(count < 1);
706	/* No outstanding writes? */
707	if (count == 1) {
708	spin_unlock(lock: &fc->lock);
709	kfree(objp: new_bucket);
710	return;
711	}
712
713	/*
714	* Completion of new bucket depends on completion of this bucket, so add
715	* one more count.
716	*/
717	atomic_inc(v: &new_bucket->count);
718	rcu_assign_pointer(fc->curr_bucket, new_bucket);
719	spin_unlock(lock: &fc->lock);
720	/*
721	* Drop initial active count. At this point if all writes in this and
722	* ancestor buckets complete, the count will go to zero and this task
723	* will be woken up.
724	*/
725	atomic_dec(v: &bucket->count);
726
727	wait_event(bucket->waitq, atomic_read(&bucket->count) == 0);
728
729	/* Drop temp count on descendant bucket */
730	fuse_sync_bucket_dec(bucket: new_bucket);
731	kfree_rcu(bucket, rcu);
732	}
733
734	static int fuse_sync_fs(struct super_block *sb, int wait)
735	{
736	struct fuse_mount *fm = get_fuse_mount_super(sb);
737	struct fuse_conn *fc = fm->fc;
738	struct fuse_syncfs_in inarg;
739	FUSE_ARGS(args);
740	int err;
741
742	/*
743	* Userspace cannot handle the wait == 0 case. Avoid a
744	* gratuitous roundtrip.
745	*/
746	if (!wait)
747	return 0;
748
749	/* The filesystem is being unmounted. Nothing to do. */
750	if (!sb->s_root)
751	return 0;
752
753	if (!fc->sync_fs)
754	return 0;
755
756	fuse_sync_fs_writes(fc);
757
758	memset(&inarg, 0, sizeof(inarg));
759	args.in_numargs = 1;
760	args.in_args[0].size = sizeof(inarg);
761	args.in_args[0].value = &inarg;
762	args.opcode = FUSE_SYNCFS;
763	args.nodeid = get_node_id(inode: sb->s_root->d_inode);
764	args.out_numargs = 0;
765
766	err = fuse_simple_request(fm, args: &args);
767	if (err == -ENOSYS) {
768	fc->sync_fs = 0;
769	err = 0;
770	}
771
772	return err;
773	}
774
775	enum {
776	OPT_SOURCE,
777	OPT_SUBTYPE,
778	OPT_FD,
779	OPT_ROOTMODE,
780	OPT_USER_ID,
781	OPT_GROUP_ID,
782	OPT_DEFAULT_PERMISSIONS,
783	OPT_ALLOW_OTHER,
784	OPT_MAX_READ,
785	OPT_BLKSIZE,
786	OPT_ERR
787	};
788
789	static const struct fs_parameter_spec fuse_fs_parameters[] = {
790	fsparam_string ("source", OPT_SOURCE),
791	fsparam_u32 ("fd", OPT_FD),
792	fsparam_u32oct ("rootmode", OPT_ROOTMODE),
793	fsparam_uid ("user_id", OPT_USER_ID),
794	fsparam_gid ("group_id", OPT_GROUP_ID),
795	fsparam_flag ("default_permissions", OPT_DEFAULT_PERMISSIONS),
796	fsparam_flag ("allow_other", OPT_ALLOW_OTHER),
797	fsparam_u32 ("max_read", OPT_MAX_READ),
798	fsparam_u32 ("blksize", OPT_BLKSIZE),
799	fsparam_string ("subtype", OPT_SUBTYPE),
800	{}
801	};
802
803	static int fuse_parse_param(struct fs_context *fsc, struct fs_parameter *param)
804	{
805	struct fs_parse_result result;
806	struct fuse_fs_context *ctx = fsc->fs_private;
807	int opt;
808	kuid_t kuid;
809	kgid_t kgid;
810
811	if (fsc->purpose == FS_CONTEXT_FOR_RECONFIGURE) {
812	/*
813	* Ignore options coming from mount(MS_REMOUNT) for backward
814	* compatibility.
815	*/
816	if (fsc->oldapi)
817	return 0;
818
819	return invalfc(fsc, "No changes allowed in reconfigure");
820	}
821
822	opt = fs_parse(fc: fsc, desc: fuse_fs_parameters, param, result: &result);
823	if (opt < 0)
824	return opt;
825
826	switch (opt) {
827	case OPT_SOURCE:
828	if (fsc->source)
829	return invalfc(fsc, "Multiple sources specified");
830	fsc->source = param->string;
831	param->string = NULL;
832	break;
833
834	case OPT_SUBTYPE:
835	if (ctx->subtype)
836	return invalfc(fsc, "Multiple subtypes specified");
837	ctx->subtype = param->string;
838	param->string = NULL;
839	return 0;
840
841	case OPT_FD:
842	ctx->fd = result.uint_32;
843	ctx->fd_present = true;
844	break;
845
846	case OPT_ROOTMODE:
847	if (!fuse_valid_type(m: result.uint_32))
848	return invalfc(fsc, "Invalid rootmode");
849	ctx->rootmode = result.uint_32;
850	ctx->rootmode_present = true;
851	break;
852
853	case OPT_USER_ID:
854	kuid = result.uid;
855	/*
856	* The requested uid must be representable in the
857	* filesystem's idmapping.
858	*/
859	if (!kuid_has_mapping(ns: fsc->user_ns, uid: kuid))
860	return invalfc(fsc, "Invalid user_id");
861	ctx->user_id = kuid;
862	ctx->user_id_present = true;
863	break;
864
865	case OPT_GROUP_ID:
866	kgid = result.gid;
867	/*
868	* The requested gid must be representable in the
869	* filesystem's idmapping.
870	*/
871	if (!kgid_has_mapping(ns: fsc->user_ns, gid: kgid))
872	return invalfc(fsc, "Invalid group_id");
873	ctx->group_id = kgid;
874	ctx->group_id_present = true;
875	break;
876
877	case OPT_DEFAULT_PERMISSIONS:
878	ctx->default_permissions = true;
879	break;
880
881	case OPT_ALLOW_OTHER:
882	ctx->allow_other = true;
883	break;
884
885	case OPT_MAX_READ:
886	ctx->max_read = result.uint_32;
887	break;
888
889	case OPT_BLKSIZE:
890	if (!ctx->is_bdev)
891	return invalfc(fsc, "blksize only supported for fuseblk");
892	ctx->blksize = result.uint_32;
893	break;
894
895	default:
896	return -EINVAL;
897	}
898
899	return 0;
900	}
901
902	static void fuse_free_fsc(struct fs_context *fsc)
903	{
904	struct fuse_fs_context *ctx = fsc->fs_private;
905
906	if (ctx) {
907	kfree(objp: ctx->subtype);
908	kfree(objp: ctx);
909	}
910	}
911
912	static int fuse_show_options(struct seq_file *m, struct dentry *root)
913	{
914	struct super_block *sb = root->d_sb;
915	struct fuse_conn *fc = get_fuse_conn_super(sb);
916
917	if (fc->legacy_opts_show) {
918	seq_printf(m, fmt: ",user_id=%u",
919	from_kuid_munged(to: fc->user_ns, uid: fc->user_id));
920	seq_printf(m, fmt: ",group_id=%u",
921	from_kgid_munged(to: fc->user_ns, gid: fc->group_id));
922	if (fc->default_permissions)
923	seq_puts(m, s: ",default_permissions");
924	if (fc->allow_other)
925	seq_puts(m, s: ",allow_other");
926	if (fc->max_read != ~0)
927	seq_printf(m, fmt: ",max_read=%u", fc->max_read);
928	if (sb->s_bdev && sb->s_blocksize != FUSE_DEFAULT_BLKSIZE)
929	seq_printf(m, fmt: ",blksize=%lu", sb->s_blocksize);
930	}
931	#ifdef CONFIG_FUSE_DAX
932	if (fc->dax_mode == FUSE_DAX_ALWAYS)
933	seq_puts(m, s: ",dax=always");
934	else if (fc->dax_mode == FUSE_DAX_NEVER)
935	seq_puts(m, s: ",dax=never");
936	else if (fc->dax_mode == FUSE_DAX_INODE_USER)
937	seq_puts(m, s: ",dax=inode");
938	#endif
939
940	return 0;
941	}
942
943	static void fuse_iqueue_init(struct fuse_iqueue *fiq,
944	const struct fuse_iqueue_ops *ops,
945	void *priv)
946	{
947	memset(fiq, 0, sizeof(struct fuse_iqueue));
948	spin_lock_init(&fiq->lock);
949	init_waitqueue_head(&fiq->waitq);
950	INIT_LIST_HEAD(list: &fiq->pending);
951	INIT_LIST_HEAD(list: &fiq->interrupts);
952	fiq->forget_list_tail = &fiq->forget_list_head;
953	fiq->connected = 1;
954	fiq->ops = ops;
955	fiq->priv = priv;
956	}
957
958	void fuse_pqueue_init(struct fuse_pqueue *fpq)
959	{
960	unsigned int i;
961
962	spin_lock_init(&fpq->lock);
963	for (i = 0; i < FUSE_PQ_HASH_SIZE; i++)
964	INIT_LIST_HEAD(list: &fpq->processing[i]);
965	INIT_LIST_HEAD(list: &fpq->io);
966	fpq->connected = 1;
967	}
968
969	void fuse_conn_init(struct fuse_conn *fc, struct fuse_mount *fm,
970	struct user_namespace *user_ns,
971	const struct fuse_iqueue_ops *fiq_ops, void *fiq_priv)
972	{
973	memset(fc, 0, sizeof(*fc));
974	spin_lock_init(&fc->lock);
975	spin_lock_init(&fc->bg_lock);
976	init_rwsem(&fc->killsb);
977	refcount_set(r: &fc->count, n: 1);
978	atomic_set(v: &fc->dev_count, i: 1);
979	atomic_set(v: &fc->epoch, i: 1);
980	INIT_WORK(&fc->epoch_work, fuse_epoch_work);
981	init_waitqueue_head(&fc->blocked_waitq);
982	fuse_iqueue_init(fiq: &fc->iq, ops: fiq_ops, priv: fiq_priv);
983	INIT_LIST_HEAD(list: &fc->bg_queue);
984	INIT_LIST_HEAD(list: &fc->entry);
985	INIT_LIST_HEAD(list: &fc->devices);
986	atomic_set(v: &fc->num_waiting, i: 0);
987	fc->max_background = FUSE_DEFAULT_MAX_BACKGROUND;
988	fc->congestion_threshold = FUSE_DEFAULT_CONGESTION_THRESHOLD;
989	atomic64_set(v: &fc->khctr, i: 0);
990	fc->polled_files = RB_ROOT;
991	fc->blocked = 0;
992	fc->initialized = 0;
993	fc->connected = 1;
994	atomic64_set(v: &fc->attr_version, i: 1);
995	atomic64_set(v: &fc->evict_ctr, i: 1);
996	get_random_bytes(buf: &fc->scramble_key, len: sizeof(fc->scramble_key));
997	fc->pid_ns = get_pid_ns(ns: task_active_pid_ns(current));
998	fc->user_ns = get_user_ns(ns: user_ns);
999	fc->max_pages = FUSE_DEFAULT_MAX_PAGES_PER_REQ;
1000	fc->max_pages_limit = fuse_max_pages_limit;
1001	fc->name_max = FUSE_NAME_LOW_MAX;
1002	fc->timeout.req_timeout = 0;
1003
1004	if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
1005	fuse_backing_files_init(fc);
1006
1007	INIT_LIST_HEAD(list: &fc->mounts);
1008	list_add(new: &fm->fc_entry, head: &fc->mounts);
1009	fm->fc = fc;
1010	}
1011	EXPORT_SYMBOL_GPL(fuse_conn_init);
1012
1013	static void delayed_release(struct rcu_head *p)
1014	{
1015	struct fuse_conn *fc = container_of(p, struct fuse_conn, rcu);
1016
1017	fuse_uring_destruct(fc);
1018
1019	put_user_ns(ns: fc->user_ns);
1020	fc->release(fc);
1021	}
1022
1023	void fuse_conn_put(struct fuse_conn *fc)
1024	{
1025	struct fuse_iqueue *fiq = &fc->iq;
1026	struct fuse_sync_bucket *bucket;
1027
1028	if (!refcount_dec_and_test(r: &fc->count))
1029	return;
1030
1031	if (IS_ENABLED(CONFIG_FUSE_DAX))
1032	fuse_dax_conn_free(fc);
1033	if (fc->timeout.req_timeout)
1034	cancel_delayed_work_sync(dwork: &fc->timeout.work);
1035	cancel_work_sync(work: &fc->epoch_work);
1036	if (fiq->ops->release)
1037	fiq->ops->release(fiq);
1038	put_pid_ns(ns: fc->pid_ns);
1039	bucket = rcu_dereference_protected(fc->curr_bucket, 1);
1040	if (bucket) {
1041	WARN_ON(atomic_read(&bucket->count) != 1);
1042	kfree(objp: bucket);
1043	}
1044	if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
1045	fuse_backing_files_free(fc);
1046	call_rcu(head: &fc->rcu, func: delayed_release);
1047	}
1048	EXPORT_SYMBOL_GPL(fuse_conn_put);
1049
1050	struct fuse_conn *fuse_conn_get(struct fuse_conn *fc)
1051	{
1052	refcount_inc(r: &fc->count);
1053	return fc;
1054	}
1055	EXPORT_SYMBOL_GPL(fuse_conn_get);
1056
1057	static struct inode *fuse_get_root_inode(struct super_block *sb, unsigned int mode)
1058	{
1059	struct fuse_attr attr;
1060	memset(&attr, 0, sizeof(attr));
1061
1062	attr.mode = mode;
1063	attr.ino = FUSE_ROOT_ID;
1064	attr.nlink = 1;
1065	return fuse_iget(sb, FUSE_ROOT_ID, generation: 0, attr: &attr, attr_valid: 0, attr_version: 0, evict_ctr: 0);
1066	}
1067
1068	struct fuse_inode_handle {
1069	u64 nodeid;
1070	u32 generation;
1071	};
1072
1073	static struct dentry *fuse_get_dentry(struct super_block *sb,
1074	struct fuse_inode_handle *handle)
1075	{
1076	struct fuse_conn *fc = get_fuse_conn_super(sb);
1077	struct inode *inode;
1078	struct dentry *entry;
1079	int err = -ESTALE;
1080
1081	if (handle->nodeid == 0)
1082	goto out_err;
1083
1084	inode = ilookup5(sb, hashval: handle->nodeid, test: fuse_inode_eq, data: &handle->nodeid);
1085	if (!inode) {
1086	struct fuse_entry_out outarg;
1087	const struct qstr name = QSTR_INIT(".", 1);
1088
1089	if (!fc->export_support)
1090	goto out_err;
1091
1092	err = fuse_lookup_name(sb, nodeid: handle->nodeid, name: &name, outarg: &outarg,
1093	inode: &inode);
1094	if (err && err != -ENOENT)
1095	goto out_err;
1096	if (err || !inode) {
1097	err = -ESTALE;
1098	goto out_err;
1099	}
1100	err = -EIO;
1101	if (get_node_id(inode) != handle->nodeid)
1102	goto out_iput;
1103	}
1104	err = -ESTALE;
1105	if (inode->i_generation != handle->generation)
1106	goto out_iput;
1107
1108	entry = d_obtain_alias(inode);
1109	if (!IS_ERR(ptr: entry) && get_node_id(inode) != FUSE_ROOT_ID)
1110	fuse_invalidate_entry_cache(entry);
1111
1112	return entry;
1113
1114	out_iput:
1115	iput(inode);
1116	out_err:
1117	return ERR_PTR(error: err);
1118	}
1119
1120	static int fuse_encode_fh(struct inode *inode, u32 *fh, int *max_len,
1121	struct inode *parent)
1122	{
1123	int len = parent ? 6 : 3;
1124	u64 nodeid;
1125	u32 generation;
1126
1127	if (*max_len < len) {
1128	*max_len = len;
1129	return FILEID_INVALID;
1130	}
1131
1132	nodeid = get_fuse_inode(inode)->nodeid;
1133	generation = inode->i_generation;
1134
1135	fh[0] = (u32)(nodeid >> 32);
1136	fh[1] = (u32)(nodeid & 0xffffffff);
1137	fh[2] = generation;
1138
1139	if (parent) {
1140	nodeid = get_fuse_inode(inode: parent)->nodeid;
1141	generation = parent->i_generation;
1142
1143	fh[3] = (u32)(nodeid >> 32);
1144	fh[4] = (u32)(nodeid & 0xffffffff);
1145	fh[5] = generation;
1146	}
1147
1148	*max_len = len;
1149	return parent ? FILEID_INO64_GEN_PARENT : FILEID_INO64_GEN;
1150	}
1151
1152	static struct dentry *fuse_fh_to_dentry(struct super_block *sb,
1153	struct fid *fid, int fh_len, int fh_type)
1154	{
1155	struct fuse_inode_handle handle;
1156
1157	if ((fh_type != FILEID_INO64_GEN &&
1158	fh_type != FILEID_INO64_GEN_PARENT) || fh_len < 3)
1159	return NULL;
1160
1161	handle.nodeid = (u64) fid->raw[0] << 32;
1162	handle.nodeid |= (u64) fid->raw[1];
1163	handle.generation = fid->raw[2];
1164	return fuse_get_dentry(sb, handle: &handle);
1165	}
1166
1167	static struct dentry *fuse_fh_to_parent(struct super_block *sb,
1168	struct fid *fid, int fh_len, int fh_type)
1169	{
1170	struct fuse_inode_handle parent;
1171
1172	if (fh_type != FILEID_INO64_GEN_PARENT || fh_len < 6)
1173	return NULL;
1174
1175	parent.nodeid = (u64) fid->raw[3] << 32;
1176	parent.nodeid |= (u64) fid->raw[4];
1177	parent.generation = fid->raw[5];
1178	return fuse_get_dentry(sb, handle: &parent);
1179	}
1180
1181	static struct dentry *fuse_get_parent(struct dentry *child)
1182	{
1183	struct inode *child_inode = d_inode(dentry: child);
1184	struct fuse_conn *fc = get_fuse_conn(inode: child_inode);
1185	struct inode *inode;
1186	struct dentry *parent;
1187	struct fuse_entry_out outarg;
1188	int err;
1189
1190	if (!fc->export_support)
1191	return ERR_PTR(error: -ESTALE);
1192
1193	err = fuse_lookup_name(sb: child_inode->i_sb, nodeid: get_node_id(inode: child_inode),
1194	name: &dotdot_name, outarg: &outarg, inode: &inode);
1195	if (err) {
1196	if (err == -ENOENT)
1197	return ERR_PTR(error: -ESTALE);
1198	return ERR_PTR(error: err);
1199	}
1200
1201	parent = d_obtain_alias(inode);
1202	if (!IS_ERR(ptr: parent) && get_node_id(inode) != FUSE_ROOT_ID)
1203	fuse_invalidate_entry_cache(entry: parent);
1204
1205	return parent;
1206	}
1207
1208	/* only for fid encoding; no support for file handle */
1209	static const struct export_operations fuse_export_fid_operations = {
1210	.encode_fh = fuse_encode_fh,
1211	};
1212
1213	static const struct export_operations fuse_export_operations = {
1214	.fh_to_dentry = fuse_fh_to_dentry,
1215	.fh_to_parent = fuse_fh_to_parent,
1216	.encode_fh = fuse_encode_fh,
1217	.get_parent = fuse_get_parent,
1218	};
1219
1220	static const struct super_operations fuse_super_operations = {
1221	.alloc_inode = fuse_alloc_inode,
1222	.free_inode = fuse_free_inode,
1223	.evict_inode = fuse_evict_inode,
1224	.write_inode = fuse_write_inode,
1225	.drop_inode = inode_just_drop,
1226	.umount_begin = fuse_umount_begin,
1227	.statfs = fuse_statfs,
1228	.sync_fs = fuse_sync_fs,
1229	.show_options = fuse_show_options,
1230	};
1231
1232	static void sanitize_global_limit(unsigned int *limit)
1233	{
1234	/*
1235	* The default maximum number of async requests is calculated to consume
1236	* 1/2^13 of the total memory, assuming 392 bytes per request.
1237	*/
1238	if (*limit == 0)
1239	*limit = ((totalram_pages() << PAGE_SHIFT) >> 13) / 392;
1240
1241	if (*limit >= 1 << 16)
1242	*limit = (1 << 16) - 1;
1243	}
1244
1245	static int set_global_limit(const char *val, const struct kernel_param *kp)
1246	{
1247	int rv;
1248
1249	rv = param_set_uint(val, kp);
1250	if (rv)
1251	return rv;
1252
1253	sanitize_global_limit(limit: (unsigned int *)kp->arg);
1254
1255	return 0;
1256	}
1257
1258	static void process_init_limits(struct fuse_conn *fc, struct fuse_init_out *arg)
1259	{
1260	int cap_sys_admin = capable(CAP_SYS_ADMIN);
1261
1262	if (arg->minor < 13)
1263	return;
1264
1265	sanitize_global_limit(limit: &max_user_bgreq);
1266	sanitize_global_limit(limit: &max_user_congthresh);
1267
1268	spin_lock(lock: &fc->bg_lock);
1269	if (arg->max_background) {
1270	fc->max_background = arg->max_background;
1271
1272	if (!cap_sys_admin && fc->max_background > max_user_bgreq)
1273	fc->max_background = max_user_bgreq;
1274	}
1275	if (arg->congestion_threshold) {
1276	fc->congestion_threshold = arg->congestion_threshold;
1277
1278	if (!cap_sys_admin &&
1279	fc->congestion_threshold > max_user_congthresh)
1280	fc->congestion_threshold = max_user_congthresh;
1281	}
1282	spin_unlock(lock: &fc->bg_lock);
1283	}
1284
1285	static void set_request_timeout(struct fuse_conn *fc, unsigned int timeout)
1286	{
1287	fc->timeout.req_timeout = secs_to_jiffies(timeout);
1288	INIT_DELAYED_WORK(&fc->timeout.work, fuse_check_timeout);
1289	queue_delayed_work(wq: system_percpu_wq, dwork: &fc->timeout.work,
1290	delay: fuse_timeout_timer_freq);
1291	}
1292
1293	static void init_server_timeout(struct fuse_conn *fc, unsigned int timeout)
1294	{
1295	if (!timeout && !fuse_max_req_timeout && !fuse_default_req_timeout)
1296	return;
1297
1298	if (!timeout)
1299	timeout = fuse_default_req_timeout;
1300
1301	if (fuse_max_req_timeout) {
1302	if (timeout)
1303	timeout = min(fuse_max_req_timeout, timeout);
1304	else
1305	timeout = fuse_max_req_timeout;
1306	}
1307
1308	timeout = max(FUSE_TIMEOUT_TIMER_FREQ, timeout);
1309
1310	set_request_timeout(fc, timeout);
1311	}
1312
1313	struct fuse_init_args {
1314	struct fuse_args args;
1315	struct fuse_init_in in;
1316	struct fuse_init_out out;
1317	};
1318
1319	static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
1320	int error)
1321	{
1322	struct fuse_conn *fc = fm->fc;
1323	struct fuse_init_args *ia = container_of(args, typeof(*ia), args);
1324	struct fuse_init_out *arg = &ia->out;
1325	bool ok = true;
1326
1327	if (error || arg->major != FUSE_KERNEL_VERSION)
1328	ok = false;
1329	else {
1330	unsigned long ra_pages;
1331	unsigned int timeout = 0;
1332
1333	process_init_limits(fc, arg);
1334
1335	if (arg->minor >= 6) {
1336	u64 flags = arg->flags;
1337
1338	if (flags & FUSE_INIT_EXT)
1339	flags |= (u64) arg->flags2 << 32;
1340
1341	ra_pages = arg->max_readahead / PAGE_SIZE;
1342	if (flags & FUSE_ASYNC_READ)
1343	fc->async_read = 1;
1344	if (!(flags & FUSE_POSIX_LOCKS))
1345	fc->no_lock = 1;
1346	if (arg->minor >= 17) {
1347	if (!(flags & FUSE_FLOCK_LOCKS))
1348	fc->no_flock = 1;
1349	} else {
1350	if (!(flags & FUSE_POSIX_LOCKS))
1351	fc->no_flock = 1;
1352	}
1353	if (flags & FUSE_ATOMIC_O_TRUNC)
1354	fc->atomic_o_trunc = 1;
1355	if (arg->minor >= 9) {
1356	/* LOOKUP has dependency on proto version */
1357	if (flags & FUSE_EXPORT_SUPPORT)
1358	fc->export_support = 1;
1359	}
1360	if (flags & FUSE_BIG_WRITES)
1361	fc->big_writes = 1;
1362	if (flags & FUSE_DONT_MASK)
1363	fc->dont_mask = 1;
1364	if (flags & FUSE_AUTO_INVAL_DATA)
1365	fc->auto_inval_data = 1;
1366	else if (flags & FUSE_EXPLICIT_INVAL_DATA)
1367	fc->explicit_inval_data = 1;
1368	if (flags & FUSE_DO_READDIRPLUS) {
1369	fc->do_readdirplus = 1;
1370	if (flags & FUSE_READDIRPLUS_AUTO)
1371	fc->readdirplus_auto = 1;
1372	}
1373	if (flags & FUSE_ASYNC_DIO)
1374	fc->async_dio = 1;
1375	if (flags & FUSE_WRITEBACK_CACHE)
1376	fc->writeback_cache = 1;
1377	if (flags & FUSE_PARALLEL_DIROPS)
1378	fc->parallel_dirops = 1;
1379	if (flags & FUSE_HANDLE_KILLPRIV)
1380	fc->handle_killpriv = 1;
1381	if (arg->time_gran && arg->time_gran <= 1000000000)
1382	fm->sb->s_time_gran = arg->time_gran;
1383	if ((flags & FUSE_POSIX_ACL)) {
1384	fc->default_permissions = 1;
1385	fc->posix_acl = 1;
1386	}
1387	if (flags & FUSE_CACHE_SYMLINKS)
1388	fc->cache_symlinks = 1;
1389	if (flags & FUSE_ABORT_ERROR)
1390	fc->abort_err = 1;
1391	if (flags & FUSE_MAX_PAGES) {
1392	fc->max_pages =
1393	min_t(unsigned int, fc->max_pages_limit,
1394	max_t(unsigned int, arg->max_pages, 1));
1395
1396	/*
1397	* PATH_MAX file names might need two pages for
1398	* ops like rename
1399	*/
1400	if (fc->max_pages > 1)
1401	fc->name_max = FUSE_NAME_MAX;
1402	}
1403	if (IS_ENABLED(CONFIG_FUSE_DAX)) {
1404	if (flags & FUSE_MAP_ALIGNMENT &&
1405	!fuse_dax_check_alignment(fc, map_alignment: arg->map_alignment)) {
1406	ok = false;
1407	}
1408	if (flags & FUSE_HAS_INODE_DAX)
1409	fc->inode_dax = 1;
1410	}
1411	if (flags & FUSE_HANDLE_KILLPRIV_V2) {
1412	fc->handle_killpriv_v2 = 1;
1413	fm->sb->s_flags |= SB_NOSEC;
1414	}
1415	if (flags & FUSE_SETXATTR_EXT)
1416	fc->setxattr_ext = 1;
1417	if (flags & FUSE_SECURITY_CTX)
1418	fc->init_security = 1;
1419	if (flags & FUSE_CREATE_SUPP_GROUP)
1420	fc->create_supp_group = 1;
1421	if (flags & FUSE_DIRECT_IO_ALLOW_MMAP)
1422	fc->direct_io_allow_mmap = 1;
1423	/*
1424	* max_stack_depth is the max stack depth of FUSE fs,
1425	* so it has to be at least 1 to support passthrough
1426	* to backing files.
1427	*
1428	* with max_stack_depth > 1, the backing files can be
1429	* on a stacked fs (e.g. overlayfs) themselves and with
1430	* max_stack_depth == 1, FUSE fs can be stacked as the
1431	* underlying fs of a stacked fs (e.g. overlayfs).
1432	*
1433	* Also don't allow the combination of FUSE_PASSTHROUGH
1434	* and FUSE_WRITEBACK_CACHE, current design doesn't handle
1435	* them together.
1436	*/
1437	if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH) &&
1438	(flags & FUSE_PASSTHROUGH) &&
1439	arg->max_stack_depth > 0 &&
1440	arg->max_stack_depth <= FILESYSTEM_MAX_STACK_DEPTH &&
1441	!(flags & FUSE_WRITEBACK_CACHE)) {
1442	fc->passthrough = 1;
1443	fc->max_stack_depth = arg->max_stack_depth;
1444	fm->sb->s_stack_depth = arg->max_stack_depth;
1445	}
1446	if (flags & FUSE_NO_EXPORT_SUPPORT)
1447	fm->sb->s_export_op = &fuse_export_fid_operations;
1448	if (flags & FUSE_ALLOW_IDMAP) {
1449	if (fc->default_permissions)
1450	fm->sb->s_iflags &= ~SB_I_NOIDMAP;
1451	else
1452	ok = false;
1453	}
1454	if (flags & FUSE_OVER_IO_URING && fuse_uring_enabled())
1455	fc->io_uring = 1;
1456
1457	if (flags & FUSE_REQUEST_TIMEOUT)
1458	timeout = arg->request_timeout;
1459	} else {
1460	ra_pages = fc->max_read / PAGE_SIZE;
1461	fc->no_lock = 1;
1462	fc->no_flock = 1;
1463	}
1464
1465	init_server_timeout(fc, timeout);
1466
1467	fm->sb->s_bdi->ra_pages =
1468	min(fm->sb->s_bdi->ra_pages, ra_pages);
1469	fc->minor = arg->minor;
1470	fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
1471	fc->max_write = max_t(unsigned, 4096, fc->max_write);
1472	fc->conn_init = 1;
1473	}
1474	kfree(objp: ia);
1475
1476	if (!ok) {
1477	fc->conn_init = 0;
1478	fc->conn_error = 1;
1479	}
1480
1481	fuse_set_initialized(fc);
1482	wake_up_all(&fc->blocked_waitq);
1483	}
1484
1485	static struct fuse_init_args *fuse_new_init(struct fuse_mount *fm)
1486	{
1487	struct fuse_init_args *ia;
1488	u64 flags;
1489
1490	ia = kzalloc(sizeof(*ia), GFP_KERNEL | __GFP_NOFAIL);
1491
1492	ia->in.major = FUSE_KERNEL_VERSION;
1493	ia->in.minor = FUSE_KERNEL_MINOR_VERSION;
1494	ia->in.max_readahead = fm->sb->s_bdi->ra_pages * PAGE_SIZE;
1495	flags =
1496	FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |
1497	FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES | FUSE_DONT_MASK |
1498	FUSE_SPLICE_WRITE | FUSE_SPLICE_MOVE | FUSE_SPLICE_READ |
1499	FUSE_FLOCK_LOCKS | FUSE_HAS_IOCTL_DIR | FUSE_AUTO_INVAL_DATA |
1500	FUSE_DO_READDIRPLUS | FUSE_READDIRPLUS_AUTO | FUSE_ASYNC_DIO |
1501	FUSE_WRITEBACK_CACHE | FUSE_NO_OPEN_SUPPORT |
1502	FUSE_PARALLEL_DIROPS | FUSE_HANDLE_KILLPRIV | FUSE_POSIX_ACL |
1503	FUSE_ABORT_ERROR | FUSE_MAX_PAGES | FUSE_CACHE_SYMLINKS |
1504	FUSE_NO_OPENDIR_SUPPORT | FUSE_EXPLICIT_INVAL_DATA |
1505	FUSE_HANDLE_KILLPRIV_V2 | FUSE_SETXATTR_EXT | FUSE_INIT_EXT |
1506	FUSE_SECURITY_CTX | FUSE_CREATE_SUPP_GROUP |
1507	FUSE_HAS_EXPIRE_ONLY | FUSE_DIRECT_IO_ALLOW_MMAP |
1508	FUSE_NO_EXPORT_SUPPORT | FUSE_HAS_RESEND | FUSE_ALLOW_IDMAP |
1509	FUSE_REQUEST_TIMEOUT;
1510	#ifdef CONFIG_FUSE_DAX
1511	if (fm->fc->dax)
1512	flags |= FUSE_MAP_ALIGNMENT;
1513	if (fuse_is_inode_dax_mode(mode: fm->fc->dax_mode))
1514	flags |= FUSE_HAS_INODE_DAX;
1515	#endif
1516	if (fm->fc->auto_submounts)
1517	flags |= FUSE_SUBMOUNTS;
1518	if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
1519	flags |= FUSE_PASSTHROUGH;
1520
1521	/*
1522	* This is just an information flag for fuse server. No need to check
1523	* the reply - server is either sending IORING_OP_URING_CMD or not.
1524	*/
1525	if (fuse_uring_enabled())
1526	flags |= FUSE_OVER_IO_URING;
1527
1528	ia->in.flags = flags;
1529	ia->in.flags2 = flags >> 32;
1530
1531	ia->args.opcode = FUSE_INIT;
1532	ia->args.in_numargs = 1;
1533	ia->args.in_args[0].size = sizeof(ia->in);
1534	ia->args.in_args[0].value = &ia->in;
1535	ia->args.out_numargs = 1;
1536	/* Variable length argument used for backward compatibility
1537	with interface version < 7.5. Rest of init_out is zeroed
1538	by do_get_request(), so a short reply is not a problem */
1539	ia->args.out_argvar = true;
1540	ia->args.out_args[0].size = sizeof(ia->out);
1541	ia->args.out_args[0].value = &ia->out;
1542	ia->args.force = true;
1543	ia->args.nocreds = true;
1544
1545	return ia;
1546	}
1547
1548	int fuse_send_init(struct fuse_mount *fm)
1549	{
1550	struct fuse_init_args *ia = fuse_new_init(fm);
1551	int err;
1552
1553	if (fm->fc->sync_init) {
1554	err = fuse_simple_request(fm, args: &ia->args);
1555	/* Ignore size of init reply */
1556	if (err > 0)
1557	err = 0;
1558	} else {
1559	ia->args.end = process_init_reply;
1560	err = fuse_simple_background(fm, args: &ia->args, GFP_KERNEL);
1561	if (!err)
1562	return 0;
1563	}
1564	process_init_reply(fm, args: &ia->args, error: err);
1565	if (fm->fc->conn_error)
1566	return -ENOTCONN;
1567	return 0;
1568	}
1569	EXPORT_SYMBOL_GPL(fuse_send_init);
1570
1571	void fuse_free_conn(struct fuse_conn *fc)
1572	{
1573	WARN_ON(!list_empty(&fc->devices));
1574	kfree(objp: fc);
1575	}
1576	EXPORT_SYMBOL_GPL(fuse_free_conn);
1577
1578	static int fuse_bdi_init(struct fuse_conn *fc, struct super_block *sb)
1579	{
1580	int err;
1581	char *suffix = "";
1582
1583	if (sb->s_bdev) {
1584	suffix = "-fuseblk";
1585	/*
1586	* sb->s_bdi points to blkdev's bdi however we want to redirect
1587	* it to our private bdi...
1588	*/
1589	bdi_put(bdi: sb->s_bdi);
1590	sb->s_bdi = &noop_backing_dev_info;
1591	}
1592	err = super_setup_bdi_name(sb, fmt: "%u:%u%s", MAJOR(fc->dev),
1593	MINOR(fc->dev), suffix);
1594	if (err)
1595	return err;
1596
1597	sb->s_bdi->capabilities |= BDI_CAP_STRICTLIMIT;
1598
1599	/*
1600	* For a single fuse filesystem use max 1% of dirty +
1601	* writeback threshold.
1602	*
1603	* This gives about 1M of write buffer for memory maps on a
1604	* machine with 1G and 10% dirty_ratio, which should be more
1605	* than enough.
1606	*
1607	* Privileged users can raise it by writing to
1608	*
1609	* /sys/class/bdi/<bdi>/max_ratio
1610	*/
1611	bdi_set_max_ratio(bdi: sb->s_bdi, max_ratio: 1);
1612
1613	return 0;
1614	}
1615
1616	struct fuse_dev *fuse_dev_alloc(void)
1617	{
1618	struct fuse_dev *fud;
1619	struct list_head *pq;
1620
1621	fud = kzalloc(sizeof(struct fuse_dev), GFP_KERNEL);
1622	if (!fud)
1623	return NULL;
1624
1625	pq = kcalloc(FUSE_PQ_HASH_SIZE, sizeof(struct list_head), GFP_KERNEL);
1626	if (!pq) {
1627	kfree(objp: fud);
1628	return NULL;
1629	}
1630
1631	fud->pq.processing = pq;
1632	fuse_pqueue_init(fpq: &fud->pq);
1633
1634	return fud;
1635	}
1636	EXPORT_SYMBOL_GPL(fuse_dev_alloc);
1637
1638	void fuse_dev_install(struct fuse_dev *fud, struct fuse_conn *fc)
1639	{
1640	fud->fc = fuse_conn_get(fc);
1641	spin_lock(lock: &fc->lock);
1642	list_add_tail(new: &fud->entry, head: &fc->devices);
1643	spin_unlock(lock: &fc->lock);
1644	}
1645	EXPORT_SYMBOL_GPL(fuse_dev_install);
1646
1647	struct fuse_dev *fuse_dev_alloc_install(struct fuse_conn *fc)
1648	{
1649	struct fuse_dev *fud;
1650
1651	fud = fuse_dev_alloc();
1652	if (!fud)
1653	return NULL;
1654
1655	fuse_dev_install(fud, fc);
1656	return fud;
1657	}
1658	EXPORT_SYMBOL_GPL(fuse_dev_alloc_install);
1659
1660	void fuse_dev_free(struct fuse_dev *fud)
1661	{
1662	struct fuse_conn *fc = fud->fc;
1663
1664	if (fc) {
1665	spin_lock(lock: &fc->lock);
1666	list_del(entry: &fud->entry);
1667	spin_unlock(lock: &fc->lock);
1668
1669	fuse_conn_put(fc);
1670	}
1671	kfree(objp: fud->pq.processing);
1672	kfree(objp: fud);
1673	}
1674	EXPORT_SYMBOL_GPL(fuse_dev_free);
1675
1676	static void fuse_fill_attr_from_inode(struct fuse_attr *attr,
1677	const struct fuse_inode *fi)
1678	{
1679	struct timespec64 atime = inode_get_atime(inode: &fi->inode);
1680	struct timespec64 mtime = inode_get_mtime(inode: &fi->inode);
1681	struct timespec64 ctime = inode_get_ctime(inode: &fi->inode);
1682
1683	*attr = (struct fuse_attr){
1684	.ino = fi->inode.i_ino,
1685	.size = fi->inode.i_size,
1686	.blocks = fi->inode.i_blocks,
1687	.atime = atime.tv_sec,
1688	.mtime = mtime.tv_sec,
1689	.ctime = ctime.tv_sec,
1690	.atimensec = atime.tv_nsec,
1691	.mtimensec = mtime.tv_nsec,
1692	.ctimensec = ctime.tv_nsec,
1693	.mode = fi->inode.i_mode,
1694	.nlink = fi->inode.i_nlink,
1695	.uid = __kuid_val(uid: fi->inode.i_uid),
1696	.gid = __kgid_val(gid: fi->inode.i_gid),
1697	.rdev = fi->inode.i_rdev,
1698	.blksize = 1u << fi->inode.i_blkbits,
1699	};
1700	}
1701
1702	static void fuse_sb_defaults(struct super_block *sb)
1703	{
1704	sb->s_magic = FUSE_SUPER_MAGIC;
1705	sb->s_op = &fuse_super_operations;
1706	sb->s_xattr = fuse_xattr_handlers;
1707	sb->s_maxbytes = MAX_LFS_FILESIZE;
1708	sb->s_time_gran = 1;
1709	sb->s_export_op = &fuse_export_operations;
1710	sb->s_iflags |= SB_I_IMA_UNVERIFIABLE_SIGNATURE;
1711	sb->s_iflags |= SB_I_NOIDMAP;
1712	if (sb->s_user_ns != &init_user_ns)
1713	sb->s_iflags |= SB_I_UNTRUSTED_MOUNTER;
1714	sb->s_flags &= ~(SB_NOSEC | SB_I_VERSION);
1715	}
1716
1717	static int fuse_fill_super_submount(struct super_block *sb,
1718	struct fuse_inode *parent_fi)
1719	{
1720	struct fuse_mount *fm = get_fuse_mount_super(sb);
1721	struct super_block *parent_sb = parent_fi->inode.i_sb;
1722	struct fuse_attr root_attr;
1723	struct inode *root;
1724	struct fuse_submount_lookup *sl;
1725	struct fuse_inode *fi;
1726
1727	fuse_sb_defaults(sb);
1728	fm->sb = sb;
1729
1730	WARN_ON(sb->s_bdi != &noop_backing_dev_info);
1731	sb->s_bdi = bdi_get(bdi: parent_sb->s_bdi);
1732
1733	sb->s_xattr = parent_sb->s_xattr;
1734	sb->s_export_op = parent_sb->s_export_op;
1735	sb->s_time_gran = parent_sb->s_time_gran;
1736	sb->s_blocksize = parent_sb->s_blocksize;
1737	sb->s_blocksize_bits = parent_sb->s_blocksize_bits;
1738	sb->s_subtype = kstrdup(s: parent_sb->s_subtype, GFP_KERNEL);
1739	if (parent_sb->s_subtype && !sb->s_subtype)
1740	return -ENOMEM;
1741
1742	fuse_fill_attr_from_inode(attr: &root_attr, fi: parent_fi);
1743	root = fuse_iget(sb, nodeid: parent_fi->nodeid, generation: 0, attr: &root_attr, attr_valid: 0, attr_version: 0,
1744	evict_ctr: fuse_get_evict_ctr(fc: fm->fc));
1745	/*
1746	* This inode is just a duplicate, so it is not looked up and
1747	* its nlookup should not be incremented. fuse_iget() does
1748	* that, though, so undo it here.
1749	*/
1750	fi = get_fuse_inode(inode: root);
1751	fi->nlookup--;
1752
1753	set_default_d_op(sb, &fuse_dentry_operations);
1754	sb->s_root = d_make_root(root);
1755	if (!sb->s_root)
1756	return -ENOMEM;
1757
1758	/*
1759	* Grab the parent's submount_lookup pointer and take a
1760	* reference on the shared nlookup from the parent. This is to
1761	* prevent the last forget for this nodeid from getting
1762	* triggered until all users have finished with it.
1763	*/
1764	sl = parent_fi->submount_lookup;
1765	WARN_ON(!sl);
1766	if (sl) {
1767	refcount_inc(r: &sl->count);
1768	fi->submount_lookup = sl;
1769	}
1770
1771	return 0;
1772	}
1773
1774	/* Filesystem context private data holds the FUSE inode of the mount point */
1775	static int fuse_get_tree_submount(struct fs_context *fsc)
1776	{
1777	struct fuse_mount *fm;
1778	struct fuse_inode *mp_fi = fsc->fs_private;
1779	struct fuse_conn *fc = get_fuse_conn(inode: &mp_fi->inode);
1780	struct super_block *sb;
1781	int err;
1782
1783	fm = kzalloc(sizeof(struct fuse_mount), GFP_KERNEL);
1784	if (!fm)
1785	return -ENOMEM;
1786
1787	fm->fc = fuse_conn_get(fc);
1788	fsc->s_fs_info = fm;
1789	sb = sget_fc(fc: fsc, NULL, set: set_anon_super_fc);
1790	if (fsc->s_fs_info)
1791	fuse_mount_destroy(fm);
1792	if (IS_ERR(ptr: sb))
1793	return PTR_ERR(ptr: sb);
1794
1795	/* Initialize superblock, making @mp_fi its root */
1796	err = fuse_fill_super_submount(sb, parent_fi: mp_fi);
1797	if (err) {
1798	deactivate_locked_super(sb);
1799	return err;
1800	}
1801
1802	down_write(sem: &fc->killsb);
1803	list_add_tail(new: &fm->fc_entry, head: &fc->mounts);
1804	up_write(sem: &fc->killsb);
1805
1806	sb->s_flags |= SB_ACTIVE;
1807	fsc->root = dget(dentry: sb->s_root);
1808
1809	return 0;
1810	}
1811
1812	static const struct fs_context_operations fuse_context_submount_ops = {
1813	.get_tree = fuse_get_tree_submount,
1814	};
1815
1816	int fuse_init_fs_context_submount(struct fs_context *fsc)
1817	{
1818	fsc->ops = &fuse_context_submount_ops;
1819	return 0;
1820	}
1821	EXPORT_SYMBOL_GPL(fuse_init_fs_context_submount);
1822
1823	int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
1824	{
1825	struct fuse_dev *fud = NULL;
1826	struct fuse_mount *fm = get_fuse_mount_super(sb);
1827	struct fuse_conn *fc = fm->fc;
1828	struct inode *root;
1829	struct dentry *root_dentry;
1830	int err;
1831
1832	err = -EINVAL;
1833	if (sb->s_flags & SB_MANDLOCK)
1834	goto err;
1835
1836	rcu_assign_pointer(fc->curr_bucket, fuse_sync_bucket_alloc());
1837	fuse_sb_defaults(sb);
1838
1839	if (ctx->is_bdev) {
1840	#ifdef CONFIG_BLOCK
1841	err = -EINVAL;
1842	if (!sb_set_blocksize(sb, size: ctx->blksize))
1843	goto err;
1844	#endif
1845	fc->sync_fs = 1;
1846	} else {
1847	sb->s_blocksize = PAGE_SIZE;
1848	sb->s_blocksize_bits = PAGE_SHIFT;
1849	}
1850
1851	sb->s_subtype = ctx->subtype;
1852	ctx->subtype = NULL;
1853	if (IS_ENABLED(CONFIG_FUSE_DAX)) {
1854	err = fuse_dax_conn_alloc(fc, mode: ctx->dax_mode, dax_dev: ctx->dax_dev);
1855	if (err)
1856	goto err;
1857	}
1858
1859	if (ctx->fudptr) {
1860	err = -ENOMEM;
1861	fud = fuse_dev_alloc_install(fc);
1862	if (!fud)
1863	goto err_free_dax;
1864	}
1865
1866	fc->dev = sb->s_dev;
1867	fm->sb = sb;
1868	err = fuse_bdi_init(fc, sb);
1869	if (err)
1870	goto err_dev_free;
1871
1872	/* Handle umasking inside the fuse code */
1873	if (sb->s_flags & SB_POSIXACL)
1874	fc->dont_mask = 1;
1875	sb->s_flags |= SB_POSIXACL;
1876
1877	fc->default_permissions = ctx->default_permissions;
1878	fc->allow_other = ctx->allow_other;
1879	fc->user_id = ctx->user_id;
1880	fc->group_id = ctx->group_id;
1881	fc->legacy_opts_show = ctx->legacy_opts_show;
1882	fc->max_read = max_t(unsigned int, 4096, ctx->max_read);
1883	fc->destroy = ctx->destroy;
1884	fc->no_control = ctx->no_control;
1885	fc->no_force_umount = ctx->no_force_umount;
1886
1887	err = -ENOMEM;
1888	root = fuse_get_root_inode(sb, mode: ctx->rootmode);
1889	set_default_d_op(sb, &fuse_dentry_operations);
1890	root_dentry = d_make_root(root);
1891	if (!root_dentry)
1892	goto err_dev_free;
1893
1894	mutex_lock(&fuse_mutex);
1895	err = -EINVAL;
1896	if (ctx->fudptr && *ctx->fudptr) {
1897	if (*ctx->fudptr == FUSE_DEV_SYNC_INIT)
1898	fc->sync_init = 1;
1899	else
1900	goto err_unlock;
1901	}
1902
1903	err = fuse_ctl_add_conn(fc);
1904	if (err)
1905	goto err_unlock;
1906
1907	list_add_tail(new: &fc->entry, head: &fuse_conn_list);
1908	sb->s_root = root_dentry;
1909	if (ctx->fudptr) {
1910	*ctx->fudptr = fud;
1911	wake_up_all(&fuse_dev_waitq);
1912	}
1913	mutex_unlock(lock: &fuse_mutex);
1914	return 0;
1915
1916	err_unlock:
1917	mutex_unlock(lock: &fuse_mutex);
1918	dput(root_dentry);
1919	err_dev_free:
1920	if (fud)
1921	fuse_dev_free(fud);
1922	err_free_dax:
1923	if (IS_ENABLED(CONFIG_FUSE_DAX))
1924	fuse_dax_conn_free(fc);
1925	err:
1926	return err;
1927	}
1928	EXPORT_SYMBOL_GPL(fuse_fill_super_common);
1929
1930	static int fuse_fill_super(struct super_block *sb, struct fs_context *fsc)
1931	{
1932	struct fuse_fs_context *ctx = fsc->fs_private;
1933	struct fuse_mount *fm;
1934	int err;
1935
1936	if (!ctx->file || !ctx->rootmode_present ||
1937	!ctx->user_id_present || !ctx->group_id_present)
1938	return -EINVAL;
1939
1940	/*
1941	* Require mount to happen from the same user namespace which
1942	* opened /dev/fuse to prevent potential attacks.
1943	*/
1944	if ((ctx->file->f_op != &fuse_dev_operations) ||
1945	(ctx->file->f_cred->user_ns != sb->s_user_ns))
1946	return -EINVAL;
1947	ctx->fudptr = &ctx->file->private_data;
1948
1949	err = fuse_fill_super_common(sb, ctx);
1950	if (err)
1951	return err;
1952	/* file->private_data shall be visible on all CPUs after this */
1953	smp_mb();
1954
1955	fm = get_fuse_mount_super(sb);
1956
1957	return fuse_send_init(fm);
1958	}
1959
1960	/*
1961	* This is the path where user supplied an already initialized fuse dev. In
1962	* this case never create a new super if the old one is gone.
1963	*/
1964	static int fuse_set_no_super(struct super_block *sb, struct fs_context *fsc)
1965	{
1966	return -ENOTCONN;
1967	}
1968
1969	static int fuse_test_super(struct super_block *sb, struct fs_context *fsc)
1970	{
1971
1972	return fsc->sget_key == get_fuse_conn_super(sb);
1973	}
1974
1975	static int fuse_get_tree(struct fs_context *fsc)
1976	{
1977	struct fuse_fs_context *ctx = fsc->fs_private;
1978	struct fuse_dev *fud;
1979	struct fuse_conn *fc;
1980	struct fuse_mount *fm;
1981	struct super_block *sb;
1982	int err;
1983
1984	fc = kmalloc(sizeof(*fc), GFP_KERNEL);
1985	if (!fc)
1986	return -ENOMEM;
1987
1988	fm = kzalloc(sizeof(*fm), GFP_KERNEL);
1989	if (!fm) {
1990	kfree(objp: fc);
1991	return -ENOMEM;
1992	}
1993
1994	fuse_conn_init(fc, fm, fsc->user_ns, &fuse_dev_fiq_ops, NULL);
1995	fc->release = fuse_free_conn;
1996
1997	fsc->s_fs_info = fm;
1998
1999	if (ctx->fd_present)
2000	ctx->file = fget(fd: ctx->fd);
2001
2002	if (IS_ENABLED(CONFIG_BLOCK) && ctx->is_bdev) {
2003	err = get_tree_bdev(fc: fsc, fill_super: fuse_fill_super);
2004	goto out;
2005	}
2006	/*
2007	* While block dev mount can be initialized with a dummy device fd
2008	* (found by device name), normal fuse mounts can't
2009	*/
2010	err = -EINVAL;
2011	if (!ctx->file)
2012	goto out;
2013
2014	/*
2015	* Allow creating a fuse mount with an already initialized fuse
2016	* connection
2017	*/
2018	fud = __fuse_get_dev(file: ctx->file);
2019	if (ctx->file->f_op == &fuse_dev_operations && fud) {
2020	fsc->sget_key = fud->fc;
2021	sb = sget_fc(fc: fsc, test: fuse_test_super, set: fuse_set_no_super);
2022	err = PTR_ERR_OR_ZERO(ptr: sb);
2023	if (!IS_ERR(ptr: sb))
2024	fsc->root = dget(dentry: sb->s_root);
2025	} else {
2026	err = get_tree_nodev(fc: fsc, fill_super: fuse_fill_super);
2027	}
2028	out:
2029	if (fsc->s_fs_info)
2030	fuse_mount_destroy(fm);
2031	if (ctx->file)
2032	fput(ctx->file);
2033	return err;
2034	}
2035
2036	static const struct fs_context_operations fuse_context_ops = {
2037	.free = fuse_free_fsc,
2038	.parse_param = fuse_parse_param,
2039	.reconfigure = fuse_reconfigure,
2040	.get_tree = fuse_get_tree,
2041	};
2042
2043	/*
2044	* Set up the filesystem mount context.
2045	*/
2046	static int fuse_init_fs_context(struct fs_context *fsc)
2047	{
2048	struct fuse_fs_context *ctx;
2049
2050	ctx = kzalloc(sizeof(struct fuse_fs_context), GFP_KERNEL);
2051	if (!ctx)
2052	return -ENOMEM;
2053
2054	ctx->max_read = ~0;
2055	ctx->blksize = FUSE_DEFAULT_BLKSIZE;
2056	ctx->legacy_opts_show = true;
2057
2058	#ifdef CONFIG_BLOCK
2059	if (fsc->fs_type == &fuseblk_fs_type) {
2060	ctx->is_bdev = true;
2061	ctx->destroy = true;
2062	}
2063	#endif
2064
2065	fsc->fs_private = ctx;
2066	fsc->ops = &fuse_context_ops;
2067	return 0;
2068	}
2069
2070	bool fuse_mount_remove(struct fuse_mount *fm)
2071	{
2072	struct fuse_conn *fc = fm->fc;
2073	bool last = false;
2074
2075	down_write(sem: &fc->killsb);
2076	list_del_init(entry: &fm->fc_entry);
2077	if (list_empty(head: &fc->mounts))
2078	last = true;
2079	up_write(sem: &fc->killsb);
2080
2081	return last;
2082	}
2083	EXPORT_SYMBOL_GPL(fuse_mount_remove);
2084
2085	void fuse_conn_destroy(struct fuse_mount *fm)
2086	{
2087	struct fuse_conn *fc = fm->fc;
2088
2089	if (fc->destroy)
2090	fuse_send_destroy(fm);
2091
2092	fuse_abort_conn(fc);
2093	fuse_wait_aborted(fc);
2094
2095	if (!list_empty(head: &fc->entry)) {
2096	mutex_lock(&fuse_mutex);
2097	list_del(entry: &fc->entry);
2098	fuse_ctl_remove_conn(fc);
2099	mutex_unlock(lock: &fuse_mutex);
2100	}
2101	}
2102	EXPORT_SYMBOL_GPL(fuse_conn_destroy);
2103
2104	static void fuse_sb_destroy(struct super_block *sb)
2105	{
2106	struct fuse_mount *fm = get_fuse_mount_super(sb);
2107	bool last;
2108
2109	if (sb->s_root) {
2110	last = fuse_mount_remove(fm);
2111	if (last)
2112	fuse_conn_destroy(fm);
2113	}
2114	}
2115
2116	void fuse_mount_destroy(struct fuse_mount *fm)
2117	{
2118	fuse_conn_put(fm->fc);
2119	kfree_rcu(fm, rcu);
2120	}
2121	EXPORT_SYMBOL(fuse_mount_destroy);
2122
2123	static void fuse_kill_sb_anon(struct super_block *sb)
2124	{
2125	fuse_sb_destroy(sb);
2126	kill_anon_super(sb);
2127	fuse_mount_destroy(get_fuse_mount_super(sb));
2128	}
2129
2130	static struct file_system_type fuse_fs_type = {
2131	.owner = THIS_MODULE,
2132	.name = "fuse",
2133	.fs_flags = FS_HAS_SUBTYPE | FS_USERNS_MOUNT | FS_ALLOW_IDMAP,
2134	.init_fs_context = fuse_init_fs_context,
2135	.parameters = fuse_fs_parameters,
2136	.kill_sb = fuse_kill_sb_anon,
2137	};
2138	MODULE_ALIAS_FS("fuse");
2139
2140	#ifdef CONFIG_BLOCK
2141	static void fuse_kill_sb_blk(struct super_block *sb)
2142	{
2143	fuse_sb_destroy(sb);
2144	kill_block_super(sb);
2145	fuse_mount_destroy(get_fuse_mount_super(sb));
2146	}
2147
2148	static struct file_system_type fuseblk_fs_type = {
2149	.owner = THIS_MODULE,
2150	.name = "fuseblk",
2151	.init_fs_context = fuse_init_fs_context,
2152	.parameters = fuse_fs_parameters,
2153	.kill_sb = fuse_kill_sb_blk,
2154	.fs_flags = FS_REQUIRES_DEV | FS_HAS_SUBTYPE | FS_ALLOW_IDMAP,
2155	};
2156	MODULE_ALIAS_FS("fuseblk");
2157
2158	static inline int register_fuseblk(void)
2159	{
2160	return register_filesystem(&fuseblk_fs_type);
2161	}
2162
2163	static inline void unregister_fuseblk(void)
2164	{
2165	unregister_filesystem(&fuseblk_fs_type);
2166	}
2167	#else
2168	static inline int register_fuseblk(void)
2169	{
2170	return 0;
2171	}
2172
2173	static inline void unregister_fuseblk(void)
2174	{
2175	}
2176	#endif
2177
2178	static void fuse_inode_init_once(void *foo)
2179	{
2180	struct inode *inode = foo;
2181
2182	inode_init_once(inode);
2183	}
2184
2185	static int __init fuse_fs_init(void)
2186	{
2187	int err;
2188
2189	fuse_inode_cachep = kmem_cache_create("fuse_inode",
2190	sizeof(struct fuse_inode), 0,
2191	SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT|SLAB_RECLAIM_ACCOUNT,
2192	fuse_inode_init_once);
2193	err = -ENOMEM;
2194	if (!fuse_inode_cachep)
2195	goto out;
2196
2197	err = register_fuseblk();
2198	if (err)
2199	goto out2;
2200
2201	err = register_filesystem(&fuse_fs_type);
2202	if (err)
2203	goto out3;
2204
2205	err = fuse_sysctl_register();
2206	if (err)
2207	goto out4;
2208
2209	return 0;
2210
2211	out4:
2212	unregister_filesystem(&fuse_fs_type);
2213	out3:
2214	unregister_fuseblk();
2215	out2:
2216	kmem_cache_destroy(s: fuse_inode_cachep);
2217	out:
2218	return err;
2219	}
2220
2221	static void fuse_fs_cleanup(void)
2222	{
2223	fuse_sysctl_unregister();
2224	unregister_filesystem(&fuse_fs_type);
2225	unregister_fuseblk();
2226
2227	/*
2228	* Make sure all delayed rcu free inodes are flushed before we
2229	* destroy cache.
2230	*/
2231	rcu_barrier();
2232	kmem_cache_destroy(s: fuse_inode_cachep);
2233	}
2234
2235	static struct kobject *fuse_kobj;
2236
2237	static int fuse_sysfs_init(void)
2238	{
2239	int err;
2240
2241	fuse_kobj = kobject_create_and_add(name: "fuse", parent: fs_kobj);
2242	if (!fuse_kobj) {
2243	err = -ENOMEM;
2244	goto out_err;
2245	}
2246
2247	err = sysfs_create_mount_point(parent_kobj: fuse_kobj, name: "connections");
2248	if (err)
2249	goto out_fuse_unregister;
2250
2251	return 0;
2252
2253	out_fuse_unregister:
2254	kobject_put(kobj: fuse_kobj);
2255	out_err:
2256	return err;
2257	}
2258
2259	static void fuse_sysfs_cleanup(void)
2260	{
2261	sysfs_remove_mount_point(parent_kobj: fuse_kobj, name: "connections");
2262	kobject_put(kobj: fuse_kobj);
2263	}
2264
2265	static int __init fuse_init(void)
2266	{
2267	int res;
2268
2269	pr_info("init (API version %i.%i)\n",
2270	FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
2271
2272	INIT_LIST_HEAD(list: &fuse_conn_list);
2273	res = fuse_fs_init();
2274	if (res)
2275	goto err;
2276
2277	res = fuse_dev_init();
2278	if (res)
2279	goto err_fs_cleanup;
2280
2281	res = fuse_sysfs_init();
2282	if (res)
2283	goto err_dev_cleanup;
2284
2285	res = fuse_ctl_init();
2286	if (res)
2287	goto err_sysfs_cleanup;
2288
2289	fuse_dentry_tree_init();
2290
2291	sanitize_global_limit(limit: &max_user_bgreq);
2292	sanitize_global_limit(limit: &max_user_congthresh);
2293
2294	return 0;
2295
2296	err_sysfs_cleanup:
2297	fuse_sysfs_cleanup();
2298	err_dev_cleanup:
2299	fuse_dev_cleanup();
2300	err_fs_cleanup:
2301	fuse_fs_cleanup();
2302	err:
2303	return res;
2304	}
2305
2306	static void __exit fuse_exit(void)
2307	{
2308	pr_debug("exit\n");
2309
2310	fuse_dentry_tree_cleanup();
2311	fuse_ctl_cleanup();
2312	fuse_sysfs_cleanup();
2313	fuse_fs_cleanup();
2314	fuse_dev_cleanup();
2315	}
2316
2317	module_init(fuse_init);
2318	module_exit(fuse_exit);
2319