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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/filter.h>
12 #include <linux/pagemap.h>
13 #include <linux/slab.h>
14 #include <linux/kernel.h>
15 #include <linux/sched.h>
16 #include <linux/sched/signal.h>
17 #include <linux/module.h>
18 #include <linux/swap.h>
19 #include <linux/falloc.h>
20 #include <linux/uio.h>
21 #include <linux/fs.h>
22 
fuse_send_open(struct fuse_mount * fm,u64 nodeid,unsigned int open_flags,int opcode,struct fuse_open_out * outargp)23 static int fuse_send_open(struct fuse_mount *fm, u64 nodeid,
24 			  unsigned int open_flags, int opcode,
25 			  struct fuse_open_out *outargp)
26 {
27 	struct fuse_open_in inarg;
28 	FUSE_ARGS(args);
29 
30 	memset(&inarg, 0, sizeof(inarg));
31 	inarg.flags = open_flags & ~(O_CREAT | O_EXCL | O_NOCTTY);
32 	if (!fm->fc->atomic_o_trunc)
33 		inarg.flags &= ~O_TRUNC;
34 
35 	if (fm->fc->handle_killpriv_v2 &&
36 	    (inarg.flags & O_TRUNC) && !capable(CAP_FSETID)) {
37 		inarg.open_flags |= FUSE_OPEN_KILL_SUIDGID;
38 	}
39 
40 	args.opcode = opcode;
41 	args.nodeid = nodeid;
42 	args.in_numargs = 1;
43 	args.in_args[0].size = sizeof(inarg);
44 	args.in_args[0].value = &inarg;
45 	args.out_numargs = 1;
46 	args.out_args[0].size = sizeof(*outargp);
47 	args.out_args[0].value = outargp;
48 
49 	return fuse_simple_request(fm, &args);
50 }
51 
52 struct fuse_release_args {
53 	struct fuse_args args;
54 	struct fuse_release_in inarg;
55 	struct inode *inode;
56 };
57 
fuse_file_alloc(struct fuse_mount * fm)58 struct fuse_file *fuse_file_alloc(struct fuse_mount *fm)
59 {
60 	struct fuse_file *ff;
61 
62 	ff = kzalloc(sizeof(struct fuse_file), GFP_KERNEL_ACCOUNT);
63 	if (unlikely(!ff))
64 		return NULL;
65 
66 	ff->fm = fm;
67 	ff->release_args = kzalloc(sizeof(*ff->release_args),
68 				   GFP_KERNEL_ACCOUNT);
69 	if (!ff->release_args) {
70 		kfree(ff);
71 		return NULL;
72 	}
73 
74 	INIT_LIST_HEAD(&ff->write_entry);
75 	mutex_init(&ff->readdir.lock);
76 	refcount_set(&ff->count, 1);
77 	RB_CLEAR_NODE(&ff->polled_node);
78 	init_waitqueue_head(&ff->poll_wait);
79 
80 	ff->kh = atomic64_inc_return(&fm->fc->khctr);
81 
82 	return ff;
83 }
84 
fuse_file_free(struct fuse_file * ff)85 void fuse_file_free(struct fuse_file *ff)
86 {
87 	kfree(ff->release_args);
88 	mutex_destroy(&ff->readdir.lock);
89 	kfree(ff);
90 }
91 
fuse_file_get(struct fuse_file * ff)92 static struct fuse_file *fuse_file_get(struct fuse_file *ff)
93 {
94 	refcount_inc(&ff->count);
95 	return ff;
96 }
97 
fuse_release_end(struct fuse_mount * fm,struct fuse_args * args,int error)98 static void fuse_release_end(struct fuse_mount *fm, struct fuse_args *args,
99 			     int error)
100 {
101 	struct fuse_release_args *ra = container_of(args, typeof(*ra), args);
102 
103 	iput(ra->inode);
104 	kfree(ra);
105 }
106 
fuse_file_put(struct inode * inode,struct fuse_file * ff,bool sync,bool isdir)107 static void fuse_file_put(struct inode *inode, struct fuse_file *ff,
108 			  bool sync, bool isdir)
109 {
110 	struct fuse_args *args = &ff->release_args->args;
111 #ifdef CONFIG_FUSE_BPF
112 	struct fuse_err_ret fer;
113 #endif
114 
115 	if (!refcount_dec_and_test(&ff->count))
116 		return;
117 
118 #ifdef CONFIG_FUSE_BPF
119 	fer = fuse_bpf_backing(inode, struct fuse_release_in,
120 		       fuse_release_initialize, fuse_release_backing,
121 		       fuse_release_finalize,
122 		       inode, ff);
123 	if (fer.ret) {
124 		fuse_release_end(ff->fm, args, 0);
125 	} else
126 #endif
127 	if (isdir ? ff->fm->fc->no_opendir : ff->fm->fc->no_open) {
128 		/* Do nothing when client does not implement 'open' */
129 		fuse_release_end(ff->fm, args, 0);
130 	} else if (sync) {
131 		fuse_simple_request(ff->fm, args);
132 		fuse_release_end(ff->fm, args, 0);
133 	} else {
134 		args->end = fuse_release_end;
135 		if (fuse_simple_background(ff->fm, args,
136 				GFP_KERNEL | __GFP_NOFAIL))
137 			fuse_release_end(ff->fm, args, -ENOTCONN);
138 	}
139 	kfree(ff);
140 }
141 
fuse_file_open(struct fuse_mount * fm,u64 nodeid,unsigned int open_flags,bool isdir)142 struct fuse_file *fuse_file_open(struct fuse_mount *fm, u64 nodeid,
143 				 unsigned int open_flags, bool isdir)
144 {
145 	struct fuse_conn *fc = fm->fc;
146 	struct fuse_file *ff;
147 	int opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
148 
149 	ff = fuse_file_alloc(fm);
150 	if (!ff)
151 		return ERR_PTR(-ENOMEM);
152 
153 	ff->fh = 0;
154 	/* Default for no-open */
155 	ff->open_flags = FOPEN_KEEP_CACHE | (isdir ? FOPEN_CACHE_DIR : 0);
156 	if (isdir ? !fc->no_opendir : !fc->no_open) {
157 		struct fuse_open_out outarg;
158 		int err;
159 
160 		err = fuse_send_open(fm, nodeid, open_flags, opcode, &outarg);
161 		if (!err) {
162 			ff->fh = outarg.fh;
163 			ff->open_flags = outarg.open_flags;
164 			fuse_passthrough_setup(fc, ff, &outarg);
165 		} else if (err != -ENOSYS) {
166 			fuse_file_free(ff);
167 			return ERR_PTR(err);
168 		} else {
169 			if (isdir)
170 				fc->no_opendir = 1;
171 			else
172 				fc->no_open = 1;
173 		}
174 	}
175 
176 	if (isdir)
177 		ff->open_flags &= ~FOPEN_DIRECT_IO;
178 
179 	ff->nodeid = nodeid;
180 
181 	return ff;
182 }
183 
fuse_do_open(struct fuse_mount * fm,u64 nodeid,struct file * file,bool isdir)184 int fuse_do_open(struct fuse_mount *fm, u64 nodeid, struct file *file,
185 		 bool isdir)
186 {
187 	struct fuse_file *ff = fuse_file_open(fm, nodeid, file->f_flags, isdir);
188 
189 	if (!IS_ERR(ff))
190 		file->private_data = ff;
191 
192 	return PTR_ERR_OR_ZERO(ff);
193 }
194 EXPORT_SYMBOL_GPL(fuse_do_open);
195 
fuse_link_write_file(struct file * file)196 static void fuse_link_write_file(struct file *file)
197 {
198 	struct inode *inode = file_inode(file);
199 	struct fuse_inode *fi = get_fuse_inode(inode);
200 	struct fuse_file *ff = file->private_data;
201 	/*
202 	 * file may be written through mmap, so chain it onto the
203 	 * inodes's write_file list
204 	 */
205 	spin_lock(&fi->lock);
206 	if (list_empty(&ff->write_entry))
207 		list_add(&ff->write_entry, &fi->write_files);
208 	spin_unlock(&fi->lock);
209 }
210 
fuse_finish_open(struct inode * inode,struct file * file)211 void fuse_finish_open(struct inode *inode, struct file *file)
212 {
213 	struct fuse_file *ff = file->private_data;
214 	struct fuse_conn *fc = get_fuse_conn(inode);
215 
216 	if (ff->open_flags & FOPEN_STREAM)
217 		stream_open(inode, file);
218 	else if (ff->open_flags & FOPEN_NONSEEKABLE)
219 		nonseekable_open(inode, file);
220 
221 	if (fc->atomic_o_trunc && (file->f_flags & O_TRUNC)) {
222 		struct fuse_inode *fi = get_fuse_inode(inode);
223 
224 		spin_lock(&fi->lock);
225 		fi->attr_version = atomic64_inc_return(&fc->attr_version);
226 		i_size_write(inode, 0);
227 		spin_unlock(&fi->lock);
228 		file_update_time(file);
229 		fuse_invalidate_attr_mask(inode, FUSE_STATX_MODSIZE);
230 	}
231 	if ((file->f_mode & FMODE_WRITE) && fc->writeback_cache)
232 		fuse_link_write_file(file);
233 }
234 
fuse_open_common(struct inode * inode,struct file * file,bool isdir)235 int fuse_open_common(struct inode *inode, struct file *file, bool isdir)
236 {
237 	struct fuse_mount *fm = get_fuse_mount(inode);
238 	struct fuse_conn *fc = fm->fc;
239 	int err;
240 	bool is_wb_truncate = (file->f_flags & O_TRUNC) &&
241 			  fc->atomic_o_trunc &&
242 			  fc->writeback_cache;
243 	bool dax_truncate = (file->f_flags & O_TRUNC) &&
244 			  fc->atomic_o_trunc && FUSE_IS_DAX(inode);
245 
246 	if (fuse_is_bad(inode))
247 		return -EIO;
248 
249 	err = generic_file_open(inode, file);
250 	if (err)
251 		return err;
252 
253 #ifdef CONFIG_FUSE_BPF
254 	{
255 		struct fuse_err_ret fer;
256 
257 		fer = fuse_bpf_backing(inode, struct fuse_open_io,
258 				       fuse_open_initialize,
259 				       fuse_open_backing,
260 				       fuse_open_finalize,
261 				       inode, file, isdir);
262 		if (fer.ret)
263 			return PTR_ERR(fer.result);
264 	}
265 #endif
266 
267 	if (is_wb_truncate || dax_truncate)
268 		inode_lock(inode);
269 
270 	if (dax_truncate) {
271 		filemap_invalidate_lock(inode->i_mapping);
272 		err = fuse_dax_break_layouts(inode, 0, 0);
273 		if (err)
274 			goto out_inode_unlock;
275 	}
276 
277 	if (is_wb_truncate || dax_truncate)
278 		fuse_set_nowrite(inode);
279 
280 	err = fuse_do_open(fm, get_node_id(inode), file, isdir);
281 	if (!err)
282 		fuse_finish_open(inode, file);
283 
284 	if (is_wb_truncate || dax_truncate)
285 		fuse_release_nowrite(inode);
286 	if (!err) {
287 		struct fuse_file *ff = file->private_data;
288 
289 		if (fc->atomic_o_trunc && (file->f_flags & O_TRUNC))
290 			truncate_pagecache(inode, 0);
291 		else if (!(ff->open_flags & FOPEN_KEEP_CACHE))
292 			invalidate_inode_pages2(inode->i_mapping);
293 	}
294 	if (dax_truncate)
295 		filemap_invalidate_unlock(inode->i_mapping);
296 out_inode_unlock:
297 	if (is_wb_truncate || dax_truncate)
298 		inode_unlock(inode);
299 
300 	return err;
301 }
302 
fuse_prepare_release(struct fuse_inode * fi,struct fuse_file * ff,unsigned int flags,int opcode)303 static void fuse_prepare_release(struct fuse_inode *fi, struct fuse_file *ff,
304 				 unsigned int flags, int opcode)
305 {
306 	struct fuse_conn *fc = ff->fm->fc;
307 	struct fuse_release_args *ra = ff->release_args;
308 
309 	/* Inode is NULL on error path of fuse_create_open() */
310 	if (likely(fi)) {
311 		spin_lock(&fi->lock);
312 		list_del(&ff->write_entry);
313 		spin_unlock(&fi->lock);
314 	}
315 	spin_lock(&fc->lock);
316 	if (!RB_EMPTY_NODE(&ff->polled_node))
317 		rb_erase(&ff->polled_node, &fc->polled_files);
318 	spin_unlock(&fc->lock);
319 
320 	wake_up_interruptible_all(&ff->poll_wait);
321 
322 	ra->inarg.fh = ff->fh;
323 	ra->inarg.flags = flags;
324 	ra->args.in_numargs = 1;
325 	ra->args.in_args[0].size = sizeof(struct fuse_release_in);
326 	ra->args.in_args[0].value = &ra->inarg;
327 	ra->args.opcode = opcode;
328 	ra->args.nodeid = ff->nodeid;
329 	ra->args.force = true;
330 	ra->args.nocreds = true;
331 }
332 
fuse_file_release(struct inode * inode,struct fuse_file * ff,unsigned int open_flags,fl_owner_t id,bool isdir)333 void fuse_file_release(struct inode *inode, struct fuse_file *ff,
334 		       unsigned int open_flags, fl_owner_t id, bool isdir)
335 {
336 	struct fuse_inode *fi = get_fuse_inode(inode);
337 	struct fuse_release_args *ra = ff->release_args;
338 	int opcode = isdir ? FUSE_RELEASEDIR : FUSE_RELEASE;
339 
340 	fuse_passthrough_release(&ff->passthrough);
341 
342 	fuse_prepare_release(fi, ff, open_flags, opcode);
343 
344 	if (ff->flock) {
345 		ra->inarg.release_flags |= FUSE_RELEASE_FLOCK_UNLOCK;
346 		ra->inarg.lock_owner = fuse_lock_owner_id(ff->fm->fc, id);
347 	}
348 	/* Hold inode until release is finished */
349 	ra->inode = igrab(inode);
350 
351 	/*
352 	 * Normally this will send the RELEASE request, however if
353 	 * some asynchronous READ or WRITE requests are outstanding,
354 	 * the sending will be delayed.
355 	 *
356 	 * Make the release synchronous if this is a fuseblk mount,
357 	 * synchronous RELEASE is allowed (and desirable) in this case
358 	 * because the server can be trusted not to screw up.
359 	 */
360 	fuse_file_put(ra->inode, ff, ff->fm->fc->destroy, isdir);
361 }
362 
fuse_release_common(struct file * file,bool isdir)363 void fuse_release_common(struct file *file, bool isdir)
364 {
365 	fuse_file_release(file_inode(file), file->private_data, file->f_flags,
366 			  (fl_owner_t) file, isdir);
367 }
368 
fuse_open(struct inode * inode,struct file * file)369 static int fuse_open(struct inode *inode, struct file *file)
370 {
371 	return fuse_open_common(inode, file, false);
372 }
373 
fuse_release(struct inode * inode,struct file * file)374 static int fuse_release(struct inode *inode, struct file *file)
375 {
376 	struct fuse_conn *fc = get_fuse_conn(inode);
377 
378 	/*
379 	 * Dirty pages might remain despite write_inode_now() call from
380 	 * fuse_flush() due to writes racing with the close.
381 	 */
382 	if (fc->writeback_cache)
383 		write_inode_now(inode, 1);
384 
385 	fuse_release_common(file, false);
386 
387 	/* return value is ignored by VFS */
388 	return 0;
389 }
390 
fuse_sync_release(struct fuse_inode * fi,struct fuse_file * ff,unsigned int flags)391 void fuse_sync_release(struct fuse_inode *fi, struct fuse_file *ff,
392 		       unsigned int flags)
393 {
394 	WARN_ON(refcount_read(&ff->count) > 1);
395 	fuse_prepare_release(fi, ff, flags, FUSE_RELEASE);
396 	/*
397 	 * iput(NULL) is a no-op and since the refcount is 1 and everything's
398 	 * synchronous, we are fine with not doing igrab() here"
399 	 */
400 	fuse_file_put(&fi->inode, ff, true, false);
401 }
402 EXPORT_SYMBOL_GPL(fuse_sync_release);
403 
404 /*
405  * Scramble the ID space with XTEA, so that the value of the files_struct
406  * pointer is not exposed to userspace.
407  */
fuse_lock_owner_id(struct fuse_conn * fc,fl_owner_t id)408 u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id)
409 {
410 	u32 *k = fc->scramble_key;
411 	u64 v = (unsigned long) id;
412 	u32 v0 = v;
413 	u32 v1 = v >> 32;
414 	u32 sum = 0;
415 	int i;
416 
417 	for (i = 0; i < 32; i++) {
418 		v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + k[sum & 3]);
419 		sum += 0x9E3779B9;
420 		v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + k[sum>>11 & 3]);
421 	}
422 
423 	return (u64) v0 + ((u64) v1 << 32);
424 }
425 
426 struct fuse_writepage_args {
427 	struct fuse_io_args ia;
428 	struct rb_node writepages_entry;
429 	struct list_head queue_entry;
430 	struct fuse_writepage_args *next;
431 	struct inode *inode;
432 	struct fuse_sync_bucket *bucket;
433 };
434 
fuse_find_writeback(struct fuse_inode * fi,pgoff_t idx_from,pgoff_t idx_to)435 static struct fuse_writepage_args *fuse_find_writeback(struct fuse_inode *fi,
436 					    pgoff_t idx_from, pgoff_t idx_to)
437 {
438 	struct rb_node *n;
439 
440 	n = fi->writepages.rb_node;
441 
442 	while (n) {
443 		struct fuse_writepage_args *wpa;
444 		pgoff_t curr_index;
445 
446 		wpa = rb_entry(n, struct fuse_writepage_args, writepages_entry);
447 		WARN_ON(get_fuse_inode(wpa->inode) != fi);
448 		curr_index = wpa->ia.write.in.offset >> PAGE_SHIFT;
449 		if (idx_from >= curr_index + wpa->ia.ap.num_pages)
450 			n = n->rb_right;
451 		else if (idx_to < curr_index)
452 			n = n->rb_left;
453 		else
454 			return wpa;
455 	}
456 	return NULL;
457 }
458 
459 /*
460  * Check if any page in a range is under writeback
461  *
462  * This is currently done by walking the list of writepage requests
463  * for the inode, which can be pretty inefficient.
464  */
fuse_range_is_writeback(struct inode * inode,pgoff_t idx_from,pgoff_t idx_to)465 static bool fuse_range_is_writeback(struct inode *inode, pgoff_t idx_from,
466 				   pgoff_t idx_to)
467 {
468 	struct fuse_inode *fi = get_fuse_inode(inode);
469 	bool found;
470 
471 	spin_lock(&fi->lock);
472 	found = fuse_find_writeback(fi, idx_from, idx_to);
473 	spin_unlock(&fi->lock);
474 
475 	return found;
476 }
477 
fuse_page_is_writeback(struct inode * inode,pgoff_t index)478 static inline bool fuse_page_is_writeback(struct inode *inode, pgoff_t index)
479 {
480 	return fuse_range_is_writeback(inode, index, index);
481 }
482 
483 /*
484  * Wait for page writeback to be completed.
485  *
486  * Since fuse doesn't rely on the VM writeback tracking, this has to
487  * use some other means.
488  */
fuse_wait_on_page_writeback(struct inode * inode,pgoff_t index)489 static void fuse_wait_on_page_writeback(struct inode *inode, pgoff_t index)
490 {
491 	struct fuse_inode *fi = get_fuse_inode(inode);
492 
493 	wait_event(fi->page_waitq, !fuse_page_is_writeback(inode, index));
494 }
495 
496 /*
497  * Wait for all pending writepages on the inode to finish.
498  *
499  * This is currently done by blocking further writes with FUSE_NOWRITE
500  * and waiting for all sent writes to complete.
501  *
502  * This must be called under i_mutex, otherwise the FUSE_NOWRITE usage
503  * could conflict with truncation.
504  */
fuse_sync_writes(struct inode * inode)505 static void fuse_sync_writes(struct inode *inode)
506 {
507 	fuse_set_nowrite(inode);
508 	fuse_release_nowrite(inode);
509 }
510 
fuse_flush(struct file * file,fl_owner_t id)511 static int fuse_flush(struct file *file, fl_owner_t id)
512 {
513 	struct inode *inode = file_inode(file);
514 	struct fuse_mount *fm = get_fuse_mount(inode);
515 	struct fuse_file *ff = file->private_data;
516 	struct fuse_flush_in inarg;
517 	FUSE_ARGS(args);
518 	int err;
519 
520 #ifdef CONFIG_FUSE_BPF
521 	struct fuse_err_ret fer;
522 
523 	fer = fuse_bpf_backing(file->f_inode, struct fuse_flush_in,
524 			       fuse_flush_initialize, fuse_flush_backing,
525 			       fuse_flush_finalize,
526 			       file, id);
527 	if (fer.ret)
528 		return PTR_ERR(fer.result);
529 #endif
530 
531 	if (fuse_is_bad(inode))
532 		return -EIO;
533 
534 	if (ff->open_flags & FOPEN_NOFLUSH && !fm->fc->writeback_cache)
535 		return 0;
536 
537 	err = write_inode_now(inode, 1);
538 	if (err)
539 		return err;
540 
541 	inode_lock(inode);
542 	fuse_sync_writes(inode);
543 	inode_unlock(inode);
544 
545 	err = filemap_check_errors(file->f_mapping);
546 	if (err)
547 		return err;
548 
549 	err = 0;
550 	if (fm->fc->no_flush)
551 		goto inval_attr_out;
552 
553 	memset(&inarg, 0, sizeof(inarg));
554 	inarg.fh = ff->fh;
555 	inarg.lock_owner = fuse_lock_owner_id(fm->fc, id);
556 	args.opcode = FUSE_FLUSH;
557 	args.nodeid = get_node_id(inode);
558 	args.in_numargs = 1;
559 	args.in_args[0].size = sizeof(inarg);
560 	args.in_args[0].value = &inarg;
561 	args.force = true;
562 
563 	err = fuse_simple_request(fm, &args);
564 	if (err == -ENOSYS) {
565 		fm->fc->no_flush = 1;
566 		err = 0;
567 	}
568 
569 inval_attr_out:
570 	/*
571 	 * In memory i_blocks is not maintained by fuse, if writeback cache is
572 	 * enabled, i_blocks from cached attr may not be accurate.
573 	 */
574 	if (!err && fm->fc->writeback_cache)
575 		fuse_invalidate_attr_mask(inode, STATX_BLOCKS);
576 	return err;
577 }
578 
fuse_fsync_common(struct file * file,loff_t start,loff_t end,int datasync,int opcode)579 int fuse_fsync_common(struct file *file, loff_t start, loff_t end,
580 		      int datasync, int opcode)
581 {
582 	struct inode *inode = file->f_mapping->host;
583 	struct fuse_mount *fm = get_fuse_mount(inode);
584 	struct fuse_file *ff = file->private_data;
585 	FUSE_ARGS(args);
586 	struct fuse_fsync_in inarg;
587 
588 	memset(&inarg, 0, sizeof(inarg));
589 	inarg.fh = ff->fh;
590 	inarg.fsync_flags = datasync ? FUSE_FSYNC_FDATASYNC : 0;
591 	args.opcode = opcode;
592 	args.nodeid = get_node_id(inode);
593 	args.in_numargs = 1;
594 	args.in_args[0].size = sizeof(inarg);
595 	args.in_args[0].value = &inarg;
596 	return fuse_simple_request(fm, &args);
597 }
598 
fuse_fsync(struct file * file,loff_t start,loff_t end,int datasync)599 static int fuse_fsync(struct file *file, loff_t start, loff_t end,
600 		      int datasync)
601 {
602 	struct inode *inode = file->f_mapping->host;
603 	struct fuse_conn *fc = get_fuse_conn(inode);
604 	int err;
605 
606 #ifdef CONFIG_FUSE_BPF
607 	struct fuse_err_ret fer;
608 
609 	fer = fuse_bpf_backing(inode, struct fuse_fsync_in,
610 			       fuse_fsync_initialize, fuse_fsync_backing,
611 			       fuse_fsync_finalize,
612 			       file, start, end, datasync);
613 	if (fer.ret)
614 		return PTR_ERR(fer.result);
615 #endif
616 
617 	if (fuse_is_bad(inode))
618 		return -EIO;
619 
620 	inode_lock(inode);
621 
622 	/*
623 	 * Start writeback against all dirty pages of the inode, then
624 	 * wait for all outstanding writes, before sending the FSYNC
625 	 * request.
626 	 */
627 	err = file_write_and_wait_range(file, start, end);
628 	if (err)
629 		goto out;
630 
631 	fuse_sync_writes(inode);
632 
633 	/*
634 	 * Due to implementation of fuse writeback
635 	 * file_write_and_wait_range() does not catch errors.
636 	 * We have to do this directly after fuse_sync_writes()
637 	 */
638 	err = file_check_and_advance_wb_err(file);
639 	if (err)
640 		goto out;
641 
642 	err = sync_inode_metadata(inode, 1);
643 	if (err)
644 		goto out;
645 
646 	if (fc->no_fsync)
647 		goto out;
648 
649 	err = fuse_fsync_common(file, start, end, datasync, FUSE_FSYNC);
650 	if (err == -ENOSYS) {
651 		fc->no_fsync = 1;
652 		err = 0;
653 	}
654 out:
655 	inode_unlock(inode);
656 
657 	return err;
658 }
659 
fuse_read_args_fill(struct fuse_io_args * ia,struct file * file,loff_t pos,size_t count,int opcode)660 void fuse_read_args_fill(struct fuse_io_args *ia, struct file *file, loff_t pos,
661 			 size_t count, int opcode)
662 {
663 	struct fuse_file *ff = file->private_data;
664 	struct fuse_args *args = &ia->ap.args;
665 
666 	ia->read.in.fh = ff->fh;
667 	ia->read.in.offset = pos;
668 	ia->read.in.size = count;
669 	ia->read.in.flags = file->f_flags;
670 	args->opcode = opcode;
671 	args->nodeid = ff->nodeid;
672 	args->in_numargs = 1;
673 	args->in_args[0].size = sizeof(ia->read.in);
674 	args->in_args[0].value = &ia->read.in;
675 	args->out_argvar = true;
676 	args->out_numargs = 1;
677 	args->out_args[0].size = count;
678 }
679 
fuse_release_user_pages(struct fuse_args_pages * ap,bool should_dirty)680 static void fuse_release_user_pages(struct fuse_args_pages *ap,
681 				    bool should_dirty)
682 {
683 	unsigned int i;
684 
685 	for (i = 0; i < ap->num_pages; i++) {
686 		if (should_dirty)
687 			set_page_dirty_lock(ap->pages[i]);
688 		put_page(ap->pages[i]);
689 	}
690 }
691 
fuse_io_release(struct kref * kref)692 static void fuse_io_release(struct kref *kref)
693 {
694 	kfree(container_of(kref, struct fuse_io_priv, refcnt));
695 }
696 
fuse_get_res_by_io(struct fuse_io_priv * io)697 static ssize_t fuse_get_res_by_io(struct fuse_io_priv *io)
698 {
699 	if (io->err)
700 		return io->err;
701 
702 	if (io->bytes >= 0 && io->write)
703 		return -EIO;
704 
705 	return io->bytes < 0 ? io->size : io->bytes;
706 }
707 
708 /**
709  * In case of short read, the caller sets 'pos' to the position of
710  * actual end of fuse request in IO request. Otherwise, if bytes_requested
711  * == bytes_transferred or rw == WRITE, the caller sets 'pos' to -1.
712  *
713  * An example:
714  * User requested DIO read of 64K. It was split into two 32K fuse requests,
715  * both submitted asynchronously. The first of them was ACKed by userspace as
716  * fully completed (req->out.args[0].size == 32K) resulting in pos == -1. The
717  * second request was ACKed as short, e.g. only 1K was read, resulting in
718  * pos == 33K.
719  *
720  * Thus, when all fuse requests are completed, the minimal non-negative 'pos'
721  * will be equal to the length of the longest contiguous fragment of
722  * transferred data starting from the beginning of IO request.
723  */
fuse_aio_complete(struct fuse_io_priv * io,int err,ssize_t pos)724 static void fuse_aio_complete(struct fuse_io_priv *io, int err, ssize_t pos)
725 {
726 	int left;
727 
728 	spin_lock(&io->lock);
729 	if (err)
730 		io->err = io->err ? : err;
731 	else if (pos >= 0 && (io->bytes < 0 || pos < io->bytes))
732 		io->bytes = pos;
733 
734 	left = --io->reqs;
735 	if (!left && io->blocking)
736 		complete(io->done);
737 	spin_unlock(&io->lock);
738 
739 	if (!left && !io->blocking) {
740 		ssize_t res = fuse_get_res_by_io(io);
741 
742 		if (res >= 0) {
743 			struct inode *inode = file_inode(io->iocb->ki_filp);
744 			struct fuse_conn *fc = get_fuse_conn(inode);
745 			struct fuse_inode *fi = get_fuse_inode(inode);
746 
747 			spin_lock(&fi->lock);
748 			fi->attr_version = atomic64_inc_return(&fc->attr_version);
749 			spin_unlock(&fi->lock);
750 		}
751 
752 		io->iocb->ki_complete(io->iocb, res);
753 	}
754 
755 	kref_put(&io->refcnt, fuse_io_release);
756 }
757 
fuse_io_alloc(struct fuse_io_priv * io,unsigned int npages)758 static struct fuse_io_args *fuse_io_alloc(struct fuse_io_priv *io,
759 					  unsigned int npages)
760 {
761 	struct fuse_io_args *ia;
762 
763 	ia = kzalloc(sizeof(*ia), GFP_KERNEL);
764 	if (ia) {
765 		ia->io = io;
766 		ia->ap.pages = fuse_pages_alloc(npages, GFP_KERNEL,
767 						&ia->ap.descs);
768 		if (!ia->ap.pages) {
769 			kfree(ia);
770 			ia = NULL;
771 		}
772 	}
773 	return ia;
774 }
775 
fuse_io_free(struct fuse_io_args * ia)776 static void fuse_io_free(struct fuse_io_args *ia)
777 {
778 	kfree(ia->ap.pages);
779 	kfree(ia);
780 }
781 
fuse_aio_complete_req(struct fuse_mount * fm,struct fuse_args * args,int err)782 static void fuse_aio_complete_req(struct fuse_mount *fm, struct fuse_args *args,
783 				  int err)
784 {
785 	struct fuse_io_args *ia = container_of(args, typeof(*ia), ap.args);
786 	struct fuse_io_priv *io = ia->io;
787 	ssize_t pos = -1;
788 
789 	fuse_release_user_pages(&ia->ap, io->should_dirty);
790 
791 	if (err) {
792 		/* Nothing */
793 	} else if (io->write) {
794 		if (ia->write.out.size > ia->write.in.size) {
795 			err = -EIO;
796 		} else if (ia->write.in.size != ia->write.out.size) {
797 			pos = ia->write.in.offset - io->offset +
798 				ia->write.out.size;
799 		}
800 	} else {
801 		u32 outsize = args->out_args[0].size;
802 
803 		if (ia->read.in.size != outsize)
804 			pos = ia->read.in.offset - io->offset + outsize;
805 	}
806 
807 	fuse_aio_complete(io, err, pos);
808 	fuse_io_free(ia);
809 }
810 
fuse_async_req_send(struct fuse_mount * fm,struct fuse_io_args * ia,size_t num_bytes)811 static ssize_t fuse_async_req_send(struct fuse_mount *fm,
812 				   struct fuse_io_args *ia, size_t num_bytes)
813 {
814 	ssize_t err;
815 	struct fuse_io_priv *io = ia->io;
816 
817 	spin_lock(&io->lock);
818 	kref_get(&io->refcnt);
819 	io->size += num_bytes;
820 	io->reqs++;
821 	spin_unlock(&io->lock);
822 
823 	ia->ap.args.end = fuse_aio_complete_req;
824 	ia->ap.args.may_block = io->should_dirty;
825 	err = fuse_simple_background(fm, &ia->ap.args, GFP_KERNEL);
826 	if (err)
827 		fuse_aio_complete_req(fm, &ia->ap.args, err);
828 
829 	return num_bytes;
830 }
831 
fuse_send_read(struct fuse_io_args * ia,loff_t pos,size_t count,fl_owner_t owner)832 static ssize_t fuse_send_read(struct fuse_io_args *ia, loff_t pos, size_t count,
833 			      fl_owner_t owner)
834 {
835 	struct file *file = ia->io->iocb->ki_filp;
836 	struct fuse_file *ff = file->private_data;
837 	struct fuse_mount *fm = ff->fm;
838 
839 	fuse_read_args_fill(ia, file, pos, count, FUSE_READ);
840 	if (owner != NULL) {
841 		ia->read.in.read_flags |= FUSE_READ_LOCKOWNER;
842 		ia->read.in.lock_owner = fuse_lock_owner_id(fm->fc, owner);
843 	}
844 
845 	if (ia->io->async)
846 		return fuse_async_req_send(fm, ia, count);
847 
848 	return fuse_simple_request(fm, &ia->ap.args);
849 }
850 
fuse_read_update_size(struct inode * inode,loff_t size,u64 attr_ver)851 static void fuse_read_update_size(struct inode *inode, loff_t size,
852 				  u64 attr_ver)
853 {
854 	struct fuse_conn *fc = get_fuse_conn(inode);
855 	struct fuse_inode *fi = get_fuse_inode(inode);
856 
857 	spin_lock(&fi->lock);
858 	if (attr_ver >= fi->attr_version && size < inode->i_size &&
859 	    !test_bit(FUSE_I_SIZE_UNSTABLE, &fi->state)) {
860 		fi->attr_version = atomic64_inc_return(&fc->attr_version);
861 		i_size_write(inode, size);
862 	}
863 	spin_unlock(&fi->lock);
864 }
865 
fuse_short_read(struct inode * inode,u64 attr_ver,size_t num_read,struct fuse_args_pages * ap)866 static void fuse_short_read(struct inode *inode, u64 attr_ver, size_t num_read,
867 			    struct fuse_args_pages *ap)
868 {
869 	struct fuse_conn *fc = get_fuse_conn(inode);
870 
871 	/*
872 	 * If writeback_cache is enabled, a short read means there's a hole in
873 	 * the file.  Some data after the hole is in page cache, but has not
874 	 * reached the client fs yet.  So the hole is not present there.
875 	 */
876 	if (!fc->writeback_cache) {
877 		loff_t pos = page_offset(ap->pages[0]) + num_read;
878 		fuse_read_update_size(inode, pos, attr_ver);
879 	}
880 }
881 
fuse_do_readpage(struct file * file,struct page * page)882 static int fuse_do_readpage(struct file *file, struct page *page)
883 {
884 	struct inode *inode = page->mapping->host;
885 	struct fuse_mount *fm = get_fuse_mount(inode);
886 	loff_t pos = page_offset(page);
887 	struct fuse_page_desc desc = { .length = PAGE_SIZE };
888 	struct fuse_io_args ia = {
889 		.ap.args.page_zeroing = true,
890 		.ap.args.out_pages = true,
891 		.ap.num_pages = 1,
892 		.ap.pages = &page,
893 		.ap.descs = &desc,
894 	};
895 	ssize_t res;
896 	u64 attr_ver;
897 
898 	/*
899 	 * Page writeback can extend beyond the lifetime of the
900 	 * page-cache page, so make sure we read a properly synced
901 	 * page.
902 	 */
903 	fuse_wait_on_page_writeback(inode, page->index);
904 
905 	attr_ver = fuse_get_attr_version(fm->fc);
906 
907 	/* Don't overflow end offset */
908 	if (pos + (desc.length - 1) == LLONG_MAX)
909 		desc.length--;
910 
911 	fuse_read_args_fill(&ia, file, pos, desc.length, FUSE_READ);
912 	res = fuse_simple_request(fm, &ia.ap.args);
913 	if (res < 0)
914 		return res;
915 	/*
916 	 * Short read means EOF.  If file size is larger, truncate it
917 	 */
918 	if (res < desc.length)
919 		fuse_short_read(inode, attr_ver, res, &ia.ap);
920 
921 	SetPageUptodate(page);
922 
923 	return 0;
924 }
925 
fuse_read_folio(struct file * file,struct folio * folio)926 static int fuse_read_folio(struct file *file, struct folio *folio)
927 {
928 	struct page *page = &folio->page;
929 	struct inode *inode = page->mapping->host;
930 	int err;
931 
932 	err = -EIO;
933 	if (fuse_is_bad(inode))
934 		goto out;
935 
936 	err = fuse_do_readpage(file, page);
937 	fuse_invalidate_atime(inode);
938  out:
939 	unlock_page(page);
940 	return err;
941 }
942 
fuse_readpages_end(struct fuse_mount * fm,struct fuse_args * args,int err)943 static void fuse_readpages_end(struct fuse_mount *fm, struct fuse_args *args,
944 			       int err)
945 {
946 	int i;
947 	struct fuse_io_args *ia = container_of(args, typeof(*ia), ap.args);
948 	struct fuse_args_pages *ap = &ia->ap;
949 	size_t count = ia->read.in.size;
950 	size_t num_read = args->out_args[0].size;
951 	struct address_space *mapping = NULL;
952 
953 	for (i = 0; mapping == NULL && i < ap->num_pages; i++)
954 		mapping = ap->pages[i]->mapping;
955 
956 	if (mapping) {
957 		struct inode *inode = mapping->host;
958 
959 		/*
960 		 * Short read means EOF. If file size is larger, truncate it
961 		 */
962 		if (!err && num_read < count)
963 			fuse_short_read(inode, ia->read.attr_ver, num_read, ap);
964 
965 		fuse_invalidate_atime(inode);
966 	}
967 
968 	for (i = 0; i < ap->num_pages; i++) {
969 		struct page *page = ap->pages[i];
970 
971 		if (!err)
972 			SetPageUptodate(page);
973 		else
974 			SetPageError(page);
975 		unlock_page(page);
976 		put_page(page);
977 	}
978 	if (ia->ff) {
979 		WARN_ON(!mapping);
980 		fuse_file_put(mapping ? mapping->host : NULL, ia->ff,
981 			      false, false);
982 	}
983 
984 	fuse_io_free(ia);
985 }
986 
fuse_send_readpages(struct fuse_io_args * ia,struct file * file)987 static void fuse_send_readpages(struct fuse_io_args *ia, struct file *file)
988 {
989 	struct fuse_file *ff = file->private_data;
990 	struct fuse_mount *fm = ff->fm;
991 	struct fuse_args_pages *ap = &ia->ap;
992 	loff_t pos = page_offset(ap->pages[0]);
993 	size_t count = ap->num_pages << PAGE_SHIFT;
994 	ssize_t res;
995 	int err;
996 
997 	ap->args.out_pages = true;
998 	ap->args.page_zeroing = true;
999 	ap->args.page_replace = true;
1000 
1001 	/* Don't overflow end offset */
1002 	if (pos + (count - 1) == LLONG_MAX) {
1003 		count--;
1004 		ap->descs[ap->num_pages - 1].length--;
1005 	}
1006 	WARN_ON((loff_t) (pos + count) < 0);
1007 
1008 	fuse_read_args_fill(ia, file, pos, count, FUSE_READ);
1009 	ia->read.attr_ver = fuse_get_attr_version(fm->fc);
1010 	if (fm->fc->async_read) {
1011 		ia->ff = fuse_file_get(ff);
1012 		ap->args.end = fuse_readpages_end;
1013 		err = fuse_simple_background(fm, &ap->args, GFP_KERNEL);
1014 		if (!err)
1015 			return;
1016 	} else {
1017 		res = fuse_simple_request(fm, &ap->args);
1018 		err = res < 0 ? res : 0;
1019 	}
1020 	fuse_readpages_end(fm, &ap->args, err);
1021 }
1022 
fuse_readahead(struct readahead_control * rac)1023 static void fuse_readahead(struct readahead_control *rac)
1024 {
1025 	struct inode *inode = rac->mapping->host;
1026 	struct fuse_conn *fc = get_fuse_conn(inode);
1027 	unsigned int i, max_pages, nr_pages = 0;
1028 
1029 #ifdef CONFIG_FUSE_BPF
1030 	/*
1031 	 * Currently no meaningful readahead is possible with fuse-bpf within
1032 	 * the kernel, so unless the daemon is aware of this file, ignore this
1033 	 * call.
1034 	 */
1035 	if (!get_fuse_inode(inode)->nodeid)
1036 		return;
1037 #endif
1038 
1039 	if (fuse_is_bad(inode))
1040 		return;
1041 
1042 	max_pages = min_t(unsigned int, fc->max_pages,
1043 			fc->max_read / PAGE_SIZE);
1044 
1045 	for (;;) {
1046 		struct fuse_io_args *ia;
1047 		struct fuse_args_pages *ap;
1048 
1049 		if (fc->num_background >= fc->congestion_threshold &&
1050 		    rac->ra->async_size >= readahead_count(rac))
1051 			/*
1052 			 * Congested and only async pages left, so skip the
1053 			 * rest.
1054 			 */
1055 			break;
1056 
1057 		nr_pages = readahead_count(rac) - nr_pages;
1058 		if (nr_pages > max_pages)
1059 			nr_pages = max_pages;
1060 		if (nr_pages == 0)
1061 			break;
1062 		ia = fuse_io_alloc(NULL, nr_pages);
1063 		if (!ia)
1064 			return;
1065 		ap = &ia->ap;
1066 		nr_pages = __readahead_batch(rac, ap->pages, nr_pages);
1067 		for (i = 0; i < nr_pages; i++) {
1068 			fuse_wait_on_page_writeback(inode,
1069 						    readahead_index(rac) + i);
1070 			ap->descs[i].length = PAGE_SIZE;
1071 		}
1072 		ap->num_pages = nr_pages;
1073 		fuse_send_readpages(ia, rac->file);
1074 	}
1075 }
1076 
fuse_cache_read_iter(struct kiocb * iocb,struct iov_iter * to)1077 static ssize_t fuse_cache_read_iter(struct kiocb *iocb, struct iov_iter *to)
1078 {
1079 	struct inode *inode = iocb->ki_filp->f_mapping->host;
1080 	struct fuse_conn *fc = get_fuse_conn(inode);
1081 
1082 	/*
1083 	 * In auto invalidate mode, always update attributes on read.
1084 	 * Otherwise, only update if we attempt to read past EOF (to ensure
1085 	 * i_size is up to date).
1086 	 */
1087 	if (fc->auto_inval_data ||
1088 	    (iocb->ki_pos + iov_iter_count(to) > i_size_read(inode))) {
1089 		int err;
1090 		err = fuse_update_attributes(inode, iocb->ki_filp, STATX_SIZE);
1091 		if (err)
1092 			return err;
1093 	}
1094 
1095 	return generic_file_read_iter(iocb, to);
1096 }
1097 
fuse_write_args_fill(struct fuse_io_args * ia,struct fuse_file * ff,loff_t pos,size_t count)1098 static void fuse_write_args_fill(struct fuse_io_args *ia, struct fuse_file *ff,
1099 				 loff_t pos, size_t count)
1100 {
1101 	struct fuse_args *args = &ia->ap.args;
1102 
1103 	ia->write.in.fh = ff->fh;
1104 	ia->write.in.offset = pos;
1105 	ia->write.in.size = count;
1106 	args->opcode = FUSE_WRITE;
1107 	args->nodeid = ff->nodeid;
1108 	args->in_numargs = 2;
1109 	if (ff->fm->fc->minor < 9)
1110 		args->in_args[0].size = FUSE_COMPAT_WRITE_IN_SIZE;
1111 	else
1112 		args->in_args[0].size = sizeof(ia->write.in);
1113 	args->in_args[0].value = &ia->write.in;
1114 	args->in_args[1].size = count;
1115 	args->out_numargs = 1;
1116 	args->out_args[0].size = sizeof(ia->write.out);
1117 	args->out_args[0].value = &ia->write.out;
1118 }
1119 
fuse_write_flags(struct kiocb * iocb)1120 static unsigned int fuse_write_flags(struct kiocb *iocb)
1121 {
1122 	unsigned int flags = iocb->ki_filp->f_flags;
1123 
1124 	if (iocb_is_dsync(iocb))
1125 		flags |= O_DSYNC;
1126 	if (iocb->ki_flags & IOCB_SYNC)
1127 		flags |= O_SYNC;
1128 
1129 	return flags;
1130 }
1131 
fuse_send_write(struct fuse_io_args * ia,loff_t pos,size_t count,fl_owner_t owner)1132 static ssize_t fuse_send_write(struct fuse_io_args *ia, loff_t pos,
1133 			       size_t count, fl_owner_t owner)
1134 {
1135 	struct kiocb *iocb = ia->io->iocb;
1136 	struct file *file = iocb->ki_filp;
1137 	struct fuse_file *ff = file->private_data;
1138 	struct fuse_mount *fm = ff->fm;
1139 	struct fuse_write_in *inarg = &ia->write.in;
1140 	ssize_t err;
1141 
1142 	fuse_write_args_fill(ia, ff, pos, count);
1143 	inarg->flags = fuse_write_flags(iocb);
1144 	if (owner != NULL) {
1145 		inarg->write_flags |= FUSE_WRITE_LOCKOWNER;
1146 		inarg->lock_owner = fuse_lock_owner_id(fm->fc, owner);
1147 	}
1148 
1149 	if (ia->io->async)
1150 		return fuse_async_req_send(fm, ia, count);
1151 
1152 	err = fuse_simple_request(fm, &ia->ap.args);
1153 	if (!err && ia->write.out.size > count)
1154 		err = -EIO;
1155 
1156 	return err ?: ia->write.out.size;
1157 }
1158 
fuse_write_update_attr(struct inode * inode,loff_t pos,ssize_t written)1159 bool fuse_write_update_attr(struct inode *inode, loff_t pos, ssize_t written)
1160 {
1161 	struct fuse_conn *fc = get_fuse_conn(inode);
1162 	struct fuse_inode *fi = get_fuse_inode(inode);
1163 	bool ret = false;
1164 
1165 	spin_lock(&fi->lock);
1166 	fi->attr_version = atomic64_inc_return(&fc->attr_version);
1167 	if (written > 0 && pos > inode->i_size) {
1168 		i_size_write(inode, pos);
1169 		ret = true;
1170 	}
1171 	spin_unlock(&fi->lock);
1172 
1173 	fuse_invalidate_attr_mask(inode, FUSE_STATX_MODSIZE);
1174 
1175 	return ret;
1176 }
1177 
fuse_send_write_pages(struct fuse_io_args * ia,struct kiocb * iocb,struct inode * inode,loff_t pos,size_t count)1178 static ssize_t fuse_send_write_pages(struct fuse_io_args *ia,
1179 				     struct kiocb *iocb, struct inode *inode,
1180 				     loff_t pos, size_t count)
1181 {
1182 	struct fuse_args_pages *ap = &ia->ap;
1183 	struct file *file = iocb->ki_filp;
1184 	struct fuse_file *ff = file->private_data;
1185 	struct fuse_mount *fm = ff->fm;
1186 	unsigned int offset, i;
1187 	bool short_write;
1188 	int err;
1189 
1190 	for (i = 0; i < ap->num_pages; i++)
1191 		fuse_wait_on_page_writeback(inode, ap->pages[i]->index);
1192 
1193 	fuse_write_args_fill(ia, ff, pos, count);
1194 	ia->write.in.flags = fuse_write_flags(iocb);
1195 	if (fm->fc->handle_killpriv_v2 && !capable(CAP_FSETID))
1196 		ia->write.in.write_flags |= FUSE_WRITE_KILL_SUIDGID;
1197 
1198 	err = fuse_simple_request(fm, &ap->args);
1199 	if (!err && ia->write.out.size > count)
1200 		err = -EIO;
1201 
1202 	short_write = ia->write.out.size < count;
1203 	offset = ap->descs[0].offset;
1204 	count = ia->write.out.size;
1205 	for (i = 0; i < ap->num_pages; i++) {
1206 		struct page *page = ap->pages[i];
1207 
1208 		if (err) {
1209 			ClearPageUptodate(page);
1210 		} else {
1211 			if (count >= PAGE_SIZE - offset)
1212 				count -= PAGE_SIZE - offset;
1213 			else {
1214 				if (short_write)
1215 					ClearPageUptodate(page);
1216 				count = 0;
1217 			}
1218 			offset = 0;
1219 		}
1220 		if (ia->write.page_locked && (i == ap->num_pages - 1))
1221 			unlock_page(page);
1222 		put_page(page);
1223 	}
1224 
1225 	return err;
1226 }
1227 
fuse_fill_write_pages(struct fuse_io_args * ia,struct address_space * mapping,struct iov_iter * ii,loff_t pos,unsigned int max_pages)1228 static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
1229 				     struct address_space *mapping,
1230 				     struct iov_iter *ii, loff_t pos,
1231 				     unsigned int max_pages)
1232 {
1233 	struct fuse_args_pages *ap = &ia->ap;
1234 	struct fuse_conn *fc = get_fuse_conn(mapping->host);
1235 	unsigned offset = pos & (PAGE_SIZE - 1);
1236 	size_t count = 0;
1237 	int err;
1238 
1239 	ap->args.in_pages = true;
1240 	ap->descs[0].offset = offset;
1241 
1242 	do {
1243 		size_t tmp;
1244 		struct page *page;
1245 		pgoff_t index = pos >> PAGE_SHIFT;
1246 		size_t bytes = min_t(size_t, PAGE_SIZE - offset,
1247 				     iov_iter_count(ii));
1248 
1249 		bytes = min_t(size_t, bytes, fc->max_write - count);
1250 
1251  again:
1252 		err = -EFAULT;
1253 		if (fault_in_iov_iter_readable(ii, bytes))
1254 			break;
1255 
1256 		err = -ENOMEM;
1257 		page = grab_cache_page_write_begin(mapping, index);
1258 		if (!page)
1259 			break;
1260 
1261 		if (mapping_writably_mapped(mapping))
1262 			flush_dcache_page(page);
1263 
1264 		tmp = copy_page_from_iter_atomic(page, offset, bytes, ii);
1265 		flush_dcache_page(page);
1266 
1267 		if (!tmp) {
1268 			unlock_page(page);
1269 			put_page(page);
1270 			goto again;
1271 		}
1272 
1273 		err = 0;
1274 		ap->pages[ap->num_pages] = page;
1275 		ap->descs[ap->num_pages].length = tmp;
1276 		ap->num_pages++;
1277 
1278 		count += tmp;
1279 		pos += tmp;
1280 		offset += tmp;
1281 		if (offset == PAGE_SIZE)
1282 			offset = 0;
1283 
1284 		/* If we copied full page, mark it uptodate */
1285 		if (tmp == PAGE_SIZE)
1286 			SetPageUptodate(page);
1287 
1288 		if (PageUptodate(page)) {
1289 			unlock_page(page);
1290 		} else {
1291 			ia->write.page_locked = true;
1292 			break;
1293 		}
1294 		if (!fc->big_writes)
1295 			break;
1296 	} while (iov_iter_count(ii) && count < fc->max_write &&
1297 		 ap->num_pages < max_pages && offset == 0);
1298 
1299 	return count > 0 ? count : err;
1300 }
1301 
fuse_wr_pages(loff_t pos,size_t len,unsigned int max_pages)1302 static inline unsigned int fuse_wr_pages(loff_t pos, size_t len,
1303 				     unsigned int max_pages)
1304 {
1305 	return min_t(unsigned int,
1306 		     ((pos + len - 1) >> PAGE_SHIFT) -
1307 		     (pos >> PAGE_SHIFT) + 1,
1308 		     max_pages);
1309 }
1310 
fuse_perform_write(struct kiocb * iocb,struct address_space * mapping,struct iov_iter * ii,loff_t pos)1311 static ssize_t fuse_perform_write(struct kiocb *iocb,
1312 				  struct address_space *mapping,
1313 				  struct iov_iter *ii, loff_t pos)
1314 {
1315 	struct inode *inode = mapping->host;
1316 	struct fuse_conn *fc = get_fuse_conn(inode);
1317 	struct fuse_inode *fi = get_fuse_inode(inode);
1318 	int err = 0;
1319 	ssize_t res = 0;
1320 
1321 	if (inode->i_size < pos + iov_iter_count(ii))
1322 		set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
1323 
1324 	do {
1325 		ssize_t count;
1326 		struct fuse_io_args ia = {};
1327 		struct fuse_args_pages *ap = &ia.ap;
1328 		unsigned int nr_pages = fuse_wr_pages(pos, iov_iter_count(ii),
1329 						      fc->max_pages);
1330 
1331 		ap->pages = fuse_pages_alloc(nr_pages, GFP_KERNEL, &ap->descs);
1332 		if (!ap->pages) {
1333 			err = -ENOMEM;
1334 			break;
1335 		}
1336 
1337 		count = fuse_fill_write_pages(&ia, mapping, ii, pos, nr_pages);
1338 		if (count <= 0) {
1339 			err = count;
1340 		} else {
1341 			err = fuse_send_write_pages(&ia, iocb, inode,
1342 						    pos, count);
1343 			if (!err) {
1344 				size_t num_written = ia.write.out.size;
1345 
1346 				res += num_written;
1347 				pos += num_written;
1348 
1349 				/* break out of the loop on short write */
1350 				if (num_written != count)
1351 					err = -EIO;
1352 			}
1353 		}
1354 		kfree(ap->pages);
1355 	} while (!err && iov_iter_count(ii));
1356 
1357 	fuse_write_update_attr(inode, pos, res);
1358 	clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
1359 
1360 	return res > 0 ? res : err;
1361 }
1362 
fuse_cache_write_iter(struct kiocb * iocb,struct iov_iter * from)1363 static ssize_t fuse_cache_write_iter(struct kiocb *iocb, struct iov_iter *from)
1364 {
1365 	struct file *file = iocb->ki_filp;
1366 	struct address_space *mapping = file->f_mapping;
1367 	ssize_t written = 0;
1368 	ssize_t written_buffered = 0;
1369 	struct inode *inode = mapping->host;
1370 	ssize_t err;
1371 	struct fuse_conn *fc = get_fuse_conn(inode);
1372 	loff_t endbyte = 0;
1373 
1374 	if (fc->writeback_cache) {
1375 		/* Update size (EOF optimization) and mode (SUID clearing) */
1376 		err = fuse_update_attributes(mapping->host, file,
1377 					     STATX_SIZE | STATX_MODE);
1378 		if (err)
1379 			return err;
1380 
1381 		if (fc->handle_killpriv_v2 &&
1382 		    setattr_should_drop_suidgid(&init_user_ns, file_inode(file))) {
1383 			goto writethrough;
1384 		}
1385 
1386 		return generic_file_write_iter(iocb, from);
1387 	}
1388 
1389 writethrough:
1390 	inode_lock(inode);
1391 
1392 	/* We can write back this queue in page reclaim */
1393 	current->backing_dev_info = inode_to_bdi(inode);
1394 
1395 	err = generic_write_checks(iocb, from);
1396 	if (err <= 0)
1397 		goto out;
1398 
1399 	err = file_remove_privs(file);
1400 	if (err)
1401 		goto out;
1402 
1403 	err = file_update_time(file);
1404 	if (err)
1405 		goto out;
1406 
1407 	if (iocb->ki_flags & IOCB_DIRECT) {
1408 		loff_t pos = iocb->ki_pos;
1409 		written = generic_file_direct_write(iocb, from);
1410 		if (written < 0 || !iov_iter_count(from))
1411 			goto out;
1412 
1413 		pos += written;
1414 
1415 		written_buffered = fuse_perform_write(iocb, mapping, from, pos);
1416 		if (written_buffered < 0) {
1417 			err = written_buffered;
1418 			goto out;
1419 		}
1420 		endbyte = pos + written_buffered - 1;
1421 
1422 		err = filemap_write_and_wait_range(file->f_mapping, pos,
1423 						   endbyte);
1424 		if (err)
1425 			goto out;
1426 
1427 		invalidate_mapping_pages(file->f_mapping,
1428 					 pos >> PAGE_SHIFT,
1429 					 endbyte >> PAGE_SHIFT);
1430 
1431 		written += written_buffered;
1432 		iocb->ki_pos = pos + written_buffered;
1433 	} else {
1434 		written = fuse_perform_write(iocb, mapping, from, iocb->ki_pos);
1435 		if (written >= 0)
1436 			iocb->ki_pos += written;
1437 	}
1438 out:
1439 	current->backing_dev_info = NULL;
1440 	inode_unlock(inode);
1441 	if (written > 0)
1442 		written = generic_write_sync(iocb, written);
1443 
1444 	return written ? written : err;
1445 }
1446 
fuse_get_user_addr(const struct iov_iter * ii)1447 static inline unsigned long fuse_get_user_addr(const struct iov_iter *ii)
1448 {
1449 	return (unsigned long)ii->iov->iov_base + ii->iov_offset;
1450 }
1451 
fuse_get_frag_size(const struct iov_iter * ii,size_t max_size)1452 static inline size_t fuse_get_frag_size(const struct iov_iter *ii,
1453 					size_t max_size)
1454 {
1455 	return min(iov_iter_single_seg_count(ii), max_size);
1456 }
1457 
fuse_get_user_pages(struct fuse_args_pages * ap,struct iov_iter * ii,size_t * nbytesp,int write,unsigned int max_pages)1458 static int fuse_get_user_pages(struct fuse_args_pages *ap, struct iov_iter *ii,
1459 			       size_t *nbytesp, int write,
1460 			       unsigned int max_pages)
1461 {
1462 	size_t nbytes = 0;  /* # bytes already packed in req */
1463 	ssize_t ret = 0;
1464 
1465 	/* Special case for kernel I/O: can copy directly into the buffer */
1466 	if (iov_iter_is_kvec(ii)) {
1467 		unsigned long user_addr = fuse_get_user_addr(ii);
1468 		size_t frag_size = fuse_get_frag_size(ii, *nbytesp);
1469 
1470 		if (write)
1471 			ap->args.in_args[1].value = (void *) user_addr;
1472 		else
1473 			ap->args.out_args[0].value = (void *) user_addr;
1474 
1475 		iov_iter_advance(ii, frag_size);
1476 		*nbytesp = frag_size;
1477 		return 0;
1478 	}
1479 
1480 	while (nbytes < *nbytesp && ap->num_pages < max_pages) {
1481 		unsigned npages;
1482 		size_t start;
1483 		ret = iov_iter_get_pages2(ii, &ap->pages[ap->num_pages],
1484 					*nbytesp - nbytes,
1485 					max_pages - ap->num_pages,
1486 					&start);
1487 		if (ret < 0)
1488 			break;
1489 
1490 		nbytes += ret;
1491 
1492 		ret += start;
1493 		npages = DIV_ROUND_UP(ret, PAGE_SIZE);
1494 
1495 		ap->descs[ap->num_pages].offset = start;
1496 		fuse_page_descs_length_init(ap->descs, ap->num_pages, npages);
1497 
1498 		ap->num_pages += npages;
1499 		ap->descs[ap->num_pages - 1].length -=
1500 			(PAGE_SIZE - ret) & (PAGE_SIZE - 1);
1501 	}
1502 
1503 	ap->args.user_pages = true;
1504 	if (write)
1505 		ap->args.in_pages = true;
1506 	else
1507 		ap->args.out_pages = true;
1508 
1509 	*nbytesp = nbytes;
1510 
1511 	return ret < 0 ? ret : 0;
1512 }
1513 
fuse_direct_io(struct fuse_io_priv * io,struct iov_iter * iter,loff_t * ppos,int flags)1514 ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
1515 		       loff_t *ppos, int flags)
1516 {
1517 	int write = flags & FUSE_DIO_WRITE;
1518 	int cuse = flags & FUSE_DIO_CUSE;
1519 	struct file *file = io->iocb->ki_filp;
1520 	struct inode *inode = file->f_mapping->host;
1521 	struct fuse_file *ff = file->private_data;
1522 	struct fuse_conn *fc = ff->fm->fc;
1523 	size_t nmax = write ? fc->max_write : fc->max_read;
1524 	loff_t pos = *ppos;
1525 	size_t count = iov_iter_count(iter);
1526 	pgoff_t idx_from = pos >> PAGE_SHIFT;
1527 	pgoff_t idx_to = (pos + count - 1) >> PAGE_SHIFT;
1528 	ssize_t res = 0;
1529 	int err = 0;
1530 	struct fuse_io_args *ia;
1531 	unsigned int max_pages;
1532 
1533 	max_pages = iov_iter_npages(iter, fc->max_pages);
1534 	ia = fuse_io_alloc(io, max_pages);
1535 	if (!ia)
1536 		return -ENOMEM;
1537 
1538 	if (!cuse && fuse_range_is_writeback(inode, idx_from, idx_to)) {
1539 		if (!write)
1540 			inode_lock(inode);
1541 		fuse_sync_writes(inode);
1542 		if (!write)
1543 			inode_unlock(inode);
1544 	}
1545 
1546 	io->should_dirty = !write && user_backed_iter(iter);
1547 	while (count) {
1548 		ssize_t nres;
1549 		fl_owner_t owner = current->files;
1550 		size_t nbytes = min(count, nmax);
1551 
1552 		err = fuse_get_user_pages(&ia->ap, iter, &nbytes, write,
1553 					  max_pages);
1554 		if (err && !nbytes)
1555 			break;
1556 
1557 		if (write) {
1558 			if (!capable(CAP_FSETID))
1559 				ia->write.in.write_flags |= FUSE_WRITE_KILL_SUIDGID;
1560 
1561 			nres = fuse_send_write(ia, pos, nbytes, owner);
1562 		} else {
1563 			nres = fuse_send_read(ia, pos, nbytes, owner);
1564 		}
1565 
1566 		if (!io->async || nres < 0) {
1567 			fuse_release_user_pages(&ia->ap, io->should_dirty);
1568 			fuse_io_free(ia);
1569 		}
1570 		ia = NULL;
1571 		if (nres < 0) {
1572 			iov_iter_revert(iter, nbytes);
1573 			err = nres;
1574 			break;
1575 		}
1576 		WARN_ON(nres > nbytes);
1577 
1578 		count -= nres;
1579 		res += nres;
1580 		pos += nres;
1581 		if (nres != nbytes) {
1582 			iov_iter_revert(iter, nbytes - nres);
1583 			break;
1584 		}
1585 		if (count) {
1586 			max_pages = iov_iter_npages(iter, fc->max_pages);
1587 			ia = fuse_io_alloc(io, max_pages);
1588 			if (!ia)
1589 				break;
1590 		}
1591 	}
1592 	if (ia)
1593 		fuse_io_free(ia);
1594 	if (res > 0)
1595 		*ppos = pos;
1596 
1597 	return res > 0 ? res : err;
1598 }
1599 EXPORT_SYMBOL_GPL(fuse_direct_io);
1600 
__fuse_direct_read(struct fuse_io_priv * io,struct iov_iter * iter,loff_t * ppos)1601 static ssize_t __fuse_direct_read(struct fuse_io_priv *io,
1602 				  struct iov_iter *iter,
1603 				  loff_t *ppos)
1604 {
1605 	ssize_t res;
1606 	struct inode *inode = file_inode(io->iocb->ki_filp);
1607 
1608 	res = fuse_direct_io(io, iter, ppos, 0);
1609 
1610 	fuse_invalidate_atime(inode);
1611 
1612 	return res;
1613 }
1614 
1615 static ssize_t fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter);
1616 
fuse_direct_read_iter(struct kiocb * iocb,struct iov_iter * to)1617 static ssize_t fuse_direct_read_iter(struct kiocb *iocb, struct iov_iter *to)
1618 {
1619 	ssize_t res;
1620 
1621 	if (!is_sync_kiocb(iocb) && iocb->ki_flags & IOCB_DIRECT) {
1622 		res = fuse_direct_IO(iocb, to);
1623 	} else {
1624 		struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(iocb);
1625 
1626 		res = __fuse_direct_read(&io, to, &iocb->ki_pos);
1627 	}
1628 
1629 	return res;
1630 }
1631 
fuse_direct_write_iter(struct kiocb * iocb,struct iov_iter * from)1632 static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from)
1633 {
1634 	struct inode *inode = file_inode(iocb->ki_filp);
1635 	struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(iocb);
1636 	ssize_t res;
1637 
1638 	/* Don't allow parallel writes to the same file */
1639 	inode_lock(inode);
1640 	res = generic_write_checks(iocb, from);
1641 	if (res > 0) {
1642 		if (!is_sync_kiocb(iocb) && iocb->ki_flags & IOCB_DIRECT) {
1643 			res = fuse_direct_IO(iocb, from);
1644 		} else {
1645 			res = fuse_direct_io(&io, from, &iocb->ki_pos,
1646 					     FUSE_DIO_WRITE);
1647 			fuse_write_update_attr(inode, iocb->ki_pos, res);
1648 		}
1649 	}
1650 	inode_unlock(inode);
1651 
1652 	return res;
1653 }
1654 
fuse_file_read_iter(struct kiocb * iocb,struct iov_iter * to)1655 static ssize_t fuse_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
1656 {
1657 	struct file *file = iocb->ki_filp;
1658 	struct fuse_file *ff = file->private_data;
1659 	struct inode *inode = file_inode(file);
1660 
1661 	if (fuse_is_bad(inode))
1662 		return -EIO;
1663 
1664 	if (FUSE_IS_DAX(inode))
1665 		return fuse_dax_read_iter(iocb, to);
1666 
1667 #ifdef CONFIG_FUSE_BPF
1668 	{
1669 		struct fuse_err_ret fer;
1670 
1671 		fer = fuse_bpf_backing(inode, struct fuse_file_read_iter_io,
1672 				       fuse_file_read_iter_initialize,
1673 				       fuse_file_read_iter_backing,
1674 				       fuse_file_read_iter_finalize,
1675 				       iocb, to);
1676 		if (fer.ret)
1677 			return PTR_ERR(fer.result);
1678 	}
1679 #endif
1680 
1681 	if (ff->passthrough.filp)
1682 		return fuse_passthrough_read_iter(iocb, to);
1683 	else if (!(ff->open_flags & FOPEN_DIRECT_IO))
1684 		return fuse_cache_read_iter(iocb, to);
1685 	else
1686 		return fuse_direct_read_iter(iocb, to);
1687 }
1688 
fuse_file_write_iter(struct kiocb * iocb,struct iov_iter * from)1689 static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
1690 {
1691 	struct file *file = iocb->ki_filp;
1692 	struct fuse_file *ff = file->private_data;
1693 	struct inode *inode = file_inode(file);
1694 
1695 	if (fuse_is_bad(inode))
1696 		return -EIO;
1697 
1698 	if (FUSE_IS_DAX(inode))
1699 		return fuse_dax_write_iter(iocb, from);
1700 
1701 #ifdef CONFIG_FUSE_BPF
1702 	{
1703 		struct fuse_err_ret fer;
1704 
1705 		fer = fuse_bpf_backing(inode, struct fuse_file_write_iter_io,
1706 				       fuse_file_write_iter_initialize,
1707 				       fuse_file_write_iter_backing,
1708 				       fuse_file_write_iter_finalize,
1709 				       iocb, from);
1710 		if (fer.ret)
1711 			return PTR_ERR(fer.result);
1712 	}
1713 #endif
1714 
1715 	if (ff->passthrough.filp)
1716 		return fuse_passthrough_write_iter(iocb, from);
1717 	else if (!(ff->open_flags & FOPEN_DIRECT_IO))
1718 		return fuse_cache_write_iter(iocb, from);
1719 	else
1720 		return fuse_direct_write_iter(iocb, from);
1721 }
1722 
fuse_writepage_free(struct fuse_writepage_args * wpa)1723 static void fuse_writepage_free(struct fuse_writepage_args *wpa)
1724 {
1725 	struct fuse_args_pages *ap = &wpa->ia.ap;
1726 	int i;
1727 
1728 	if (wpa->bucket)
1729 		fuse_sync_bucket_dec(wpa->bucket);
1730 
1731 	for (i = 0; i < ap->num_pages; i++)
1732 		__free_page(ap->pages[i]);
1733 
1734 	if (wpa->ia.ff)
1735 		fuse_file_put(wpa->inode, wpa->ia.ff, false, false);
1736 
1737 	kfree(ap->pages);
1738 	kfree(wpa);
1739 }
1740 
fuse_writepage_finish(struct fuse_mount * fm,struct fuse_writepage_args * wpa)1741 static void fuse_writepage_finish(struct fuse_mount *fm,
1742 				  struct fuse_writepage_args *wpa)
1743 {
1744 	struct fuse_args_pages *ap = &wpa->ia.ap;
1745 	struct inode *inode = wpa->inode;
1746 	struct fuse_inode *fi = get_fuse_inode(inode);
1747 	struct backing_dev_info *bdi = inode_to_bdi(inode);
1748 	int i;
1749 
1750 	for (i = 0; i < ap->num_pages; i++) {
1751 		dec_wb_stat(&bdi->wb, WB_WRITEBACK);
1752 		dec_node_page_state(ap->pages[i], NR_WRITEBACK_TEMP);
1753 		wb_writeout_inc(&bdi->wb);
1754 	}
1755 	wake_up(&fi->page_waitq);
1756 }
1757 
1758 /* Called under fi->lock, may release and reacquire it */
fuse_send_writepage(struct fuse_mount * fm,struct fuse_writepage_args * wpa,loff_t size)1759 static void fuse_send_writepage(struct fuse_mount *fm,
1760 				struct fuse_writepage_args *wpa, loff_t size)
1761 __releases(fi->lock)
1762 __acquires(fi->lock)
1763 {
1764 	struct fuse_writepage_args *aux, *next;
1765 	struct fuse_inode *fi = get_fuse_inode(wpa->inode);
1766 	struct fuse_write_in *inarg = &wpa->ia.write.in;
1767 	struct fuse_args *args = &wpa->ia.ap.args;
1768 	__u64 data_size = wpa->ia.ap.num_pages * PAGE_SIZE;
1769 	int err;
1770 
1771 	fi->writectr++;
1772 	if (inarg->offset + data_size <= size) {
1773 		inarg->size = data_size;
1774 	} else if (inarg->offset < size) {
1775 		inarg->size = size - inarg->offset;
1776 	} else {
1777 		/* Got truncated off completely */
1778 		goto out_free;
1779 	}
1780 
1781 	args->in_args[1].size = inarg->size;
1782 	args->force = true;
1783 	args->nocreds = true;
1784 
1785 	err = fuse_simple_background(fm, args, GFP_ATOMIC);
1786 	if (err == -ENOMEM) {
1787 		spin_unlock(&fi->lock);
1788 		err = fuse_simple_background(fm, args, GFP_NOFS | __GFP_NOFAIL);
1789 		spin_lock(&fi->lock);
1790 	}
1791 
1792 	/* Fails on broken connection only */
1793 	if (unlikely(err))
1794 		goto out_free;
1795 
1796 	return;
1797 
1798  out_free:
1799 	fi->writectr--;
1800 	rb_erase(&wpa->writepages_entry, &fi->writepages);
1801 	fuse_writepage_finish(fm, wpa);
1802 	spin_unlock(&fi->lock);
1803 
1804 	/* After fuse_writepage_finish() aux request list is private */
1805 	for (aux = wpa->next; aux; aux = next) {
1806 		next = aux->next;
1807 		aux->next = NULL;
1808 		fuse_writepage_free(aux);
1809 	}
1810 
1811 	fuse_writepage_free(wpa);
1812 	spin_lock(&fi->lock);
1813 }
1814 
1815 /*
1816  * If fi->writectr is positive (no truncate or fsync going on) send
1817  * all queued writepage requests.
1818  *
1819  * Called with fi->lock
1820  */
fuse_flush_writepages(struct inode * inode)1821 void fuse_flush_writepages(struct inode *inode)
1822 __releases(fi->lock)
1823 __acquires(fi->lock)
1824 {
1825 	struct fuse_mount *fm = get_fuse_mount(inode);
1826 	struct fuse_inode *fi = get_fuse_inode(inode);
1827 	loff_t crop = i_size_read(inode);
1828 	struct fuse_writepage_args *wpa;
1829 
1830 	while (fi->writectr >= 0 && !list_empty(&fi->queued_writes)) {
1831 		wpa = list_entry(fi->queued_writes.next,
1832 				 struct fuse_writepage_args, queue_entry);
1833 		list_del_init(&wpa->queue_entry);
1834 		fuse_send_writepage(fm, wpa, crop);
1835 	}
1836 }
1837 
fuse_insert_writeback(struct rb_root * root,struct fuse_writepage_args * wpa)1838 static struct fuse_writepage_args *fuse_insert_writeback(struct rb_root *root,
1839 						struct fuse_writepage_args *wpa)
1840 {
1841 	pgoff_t idx_from = wpa->ia.write.in.offset >> PAGE_SHIFT;
1842 	pgoff_t idx_to = idx_from + wpa->ia.ap.num_pages - 1;
1843 	struct rb_node **p = &root->rb_node;
1844 	struct rb_node  *parent = NULL;
1845 
1846 	WARN_ON(!wpa->ia.ap.num_pages);
1847 	while (*p) {
1848 		struct fuse_writepage_args *curr;
1849 		pgoff_t curr_index;
1850 
1851 		parent = *p;
1852 		curr = rb_entry(parent, struct fuse_writepage_args,
1853 				writepages_entry);
1854 		WARN_ON(curr->inode != wpa->inode);
1855 		curr_index = curr->ia.write.in.offset >> PAGE_SHIFT;
1856 
1857 		if (idx_from >= curr_index + curr->ia.ap.num_pages)
1858 			p = &(*p)->rb_right;
1859 		else if (idx_to < curr_index)
1860 			p = &(*p)->rb_left;
1861 		else
1862 			return curr;
1863 	}
1864 
1865 	rb_link_node(&wpa->writepages_entry, parent, p);
1866 	rb_insert_color(&wpa->writepages_entry, root);
1867 	return NULL;
1868 }
1869 
tree_insert(struct rb_root * root,struct fuse_writepage_args * wpa)1870 static void tree_insert(struct rb_root *root, struct fuse_writepage_args *wpa)
1871 {
1872 	WARN_ON(fuse_insert_writeback(root, wpa));
1873 }
1874 
fuse_writepage_end(struct fuse_mount * fm,struct fuse_args * args,int error)1875 static void fuse_writepage_end(struct fuse_mount *fm, struct fuse_args *args,
1876 			       int error)
1877 {
1878 	struct fuse_writepage_args *wpa =
1879 		container_of(args, typeof(*wpa), ia.ap.args);
1880 	struct inode *inode = wpa->inode;
1881 	struct fuse_inode *fi = get_fuse_inode(inode);
1882 	struct fuse_conn *fc = get_fuse_conn(inode);
1883 
1884 	mapping_set_error(inode->i_mapping, error);
1885 	/*
1886 	 * A writeback finished and this might have updated mtime/ctime on
1887 	 * server making local mtime/ctime stale.  Hence invalidate attrs.
1888 	 * Do this only if writeback_cache is not enabled.  If writeback_cache
1889 	 * is enabled, we trust local ctime/mtime.
1890 	 */
1891 	if (!fc->writeback_cache)
1892 		fuse_invalidate_attr_mask(inode, FUSE_STATX_MODIFY);
1893 	spin_lock(&fi->lock);
1894 	rb_erase(&wpa->writepages_entry, &fi->writepages);
1895 	while (wpa->next) {
1896 		struct fuse_mount *fm = get_fuse_mount(inode);
1897 		struct fuse_write_in *inarg = &wpa->ia.write.in;
1898 		struct fuse_writepage_args *next = wpa->next;
1899 
1900 		wpa->next = next->next;
1901 		next->next = NULL;
1902 		next->ia.ff = fuse_file_get(wpa->ia.ff);
1903 		tree_insert(&fi->writepages, next);
1904 
1905 		/*
1906 		 * Skip fuse_flush_writepages() to make it easy to crop requests
1907 		 * based on primary request size.
1908 		 *
1909 		 * 1st case (trivial): there are no concurrent activities using
1910 		 * fuse_set/release_nowrite.  Then we're on safe side because
1911 		 * fuse_flush_writepages() would call fuse_send_writepage()
1912 		 * anyway.
1913 		 *
1914 		 * 2nd case: someone called fuse_set_nowrite and it is waiting
1915 		 * now for completion of all in-flight requests.  This happens
1916 		 * rarely and no more than once per page, so this should be
1917 		 * okay.
1918 		 *
1919 		 * 3rd case: someone (e.g. fuse_do_setattr()) is in the middle
1920 		 * of fuse_set_nowrite..fuse_release_nowrite section.  The fact
1921 		 * that fuse_set_nowrite returned implies that all in-flight
1922 		 * requests were completed along with all of their secondary
1923 		 * requests.  Further primary requests are blocked by negative
1924 		 * writectr.  Hence there cannot be any in-flight requests and
1925 		 * no invocations of fuse_writepage_end() while we're in
1926 		 * fuse_set_nowrite..fuse_release_nowrite section.
1927 		 */
1928 		fuse_send_writepage(fm, next, inarg->offset + inarg->size);
1929 	}
1930 	fi->writectr--;
1931 	fuse_writepage_finish(fm, wpa);
1932 	spin_unlock(&fi->lock);
1933 	fuse_writepage_free(wpa);
1934 }
1935 
__fuse_write_file_get(struct fuse_inode * fi)1936 static struct fuse_file *__fuse_write_file_get(struct fuse_inode *fi)
1937 {
1938 	struct fuse_file *ff;
1939 
1940 	spin_lock(&fi->lock);
1941 	ff = list_first_entry_or_null(&fi->write_files, struct fuse_file,
1942 				      write_entry);
1943 	if (ff)
1944 		fuse_file_get(ff);
1945 	spin_unlock(&fi->lock);
1946 
1947 	return ff;
1948 }
1949 
fuse_write_file_get(struct fuse_inode * fi)1950 static struct fuse_file *fuse_write_file_get(struct fuse_inode *fi)
1951 {
1952 	struct fuse_file *ff = __fuse_write_file_get(fi);
1953 	WARN_ON(!ff);
1954 	return ff;
1955 }
1956 
fuse_write_inode(struct inode * inode,struct writeback_control * wbc)1957 int fuse_write_inode(struct inode *inode, struct writeback_control *wbc)
1958 {
1959 	struct fuse_inode *fi = get_fuse_inode(inode);
1960 	struct fuse_file *ff;
1961 	int err;
1962 
1963 	/**
1964 	 * TODO - fully understand why this is necessary
1965 	 *
1966 	 * With fuse-bpf, fsstress fails if rename is enabled without this
1967 	 *
1968 	 * We are getting writes here on directory inodes, which do not have an
1969 	 * initialized file list so crash.
1970 	 *
1971 	 * The question is why we are getting those writes
1972 	 */
1973 	if (!S_ISREG(inode->i_mode))
1974 		return 0;
1975 
1976 	/*
1977 	 * Inode is always written before the last reference is dropped and
1978 	 * hence this should not be reached from reclaim.
1979 	 *
1980 	 * Writing back the inode from reclaim can deadlock if the request
1981 	 * processing itself needs an allocation.  Allocations triggering
1982 	 * reclaim while serving a request can't be prevented, because it can
1983 	 * involve any number of unrelated userspace processes.
1984 	 */
1985 	WARN_ON(wbc->for_reclaim);
1986 
1987 	ff = __fuse_write_file_get(fi);
1988 	err = fuse_flush_times(inode, ff);
1989 	if (ff)
1990 		fuse_file_put(inode, ff, false, false);
1991 
1992 	return err;
1993 }
1994 
fuse_writepage_args_alloc(void)1995 static struct fuse_writepage_args *fuse_writepage_args_alloc(void)
1996 {
1997 	struct fuse_writepage_args *wpa;
1998 	struct fuse_args_pages *ap;
1999 
2000 	wpa = kzalloc(sizeof(*wpa), GFP_NOFS);
2001 	if (wpa) {
2002 		ap = &wpa->ia.ap;
2003 		ap->num_pages = 0;
2004 		ap->pages = fuse_pages_alloc(1, GFP_NOFS, &ap->descs);
2005 		if (!ap->pages) {
2006 			kfree(wpa);
2007 			wpa = NULL;
2008 		}
2009 	}
2010 	return wpa;
2011 
2012 }
2013 
fuse_writepage_add_to_bucket(struct fuse_conn * fc,struct fuse_writepage_args * wpa)2014 static void fuse_writepage_add_to_bucket(struct fuse_conn *fc,
2015 					 struct fuse_writepage_args *wpa)
2016 {
2017 	if (!fc->sync_fs)
2018 		return;
2019 
2020 	rcu_read_lock();
2021 	/* Prevent resurrection of dead bucket in unlikely race with syncfs */
2022 	do {
2023 		wpa->bucket = rcu_dereference(fc->curr_bucket);
2024 	} while (unlikely(!atomic_inc_not_zero(&wpa->bucket->count)));
2025 	rcu_read_unlock();
2026 }
2027 
fuse_writepage_locked(struct page * page)2028 static int fuse_writepage_locked(struct page *page)
2029 {
2030 	struct address_space *mapping = page->mapping;
2031 	struct inode *inode = mapping->host;
2032 	struct fuse_conn *fc = get_fuse_conn(inode);
2033 	struct fuse_inode *fi = get_fuse_inode(inode);
2034 	struct fuse_writepage_args *wpa;
2035 	struct fuse_args_pages *ap;
2036 	struct page *tmp_page;
2037 	int error = -ENOMEM;
2038 
2039 	set_page_writeback(page);
2040 
2041 	wpa = fuse_writepage_args_alloc();
2042 	if (!wpa)
2043 		goto err;
2044 	ap = &wpa->ia.ap;
2045 
2046 	tmp_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
2047 	if (!tmp_page)
2048 		goto err_free;
2049 
2050 	error = -EIO;
2051 	wpa->ia.ff = fuse_write_file_get(fi);
2052 	if (!wpa->ia.ff)
2053 		goto err_nofile;
2054 
2055 	fuse_writepage_add_to_bucket(fc, wpa);
2056 	fuse_write_args_fill(&wpa->ia, wpa->ia.ff, page_offset(page), 0);
2057 
2058 	copy_highpage(tmp_page, page);
2059 	wpa->ia.write.in.write_flags |= FUSE_WRITE_CACHE;
2060 	wpa->next = NULL;
2061 	ap->args.in_pages = true;
2062 	ap->num_pages = 1;
2063 	ap->pages[0] = tmp_page;
2064 	ap->descs[0].offset = 0;
2065 	ap->descs[0].length = PAGE_SIZE;
2066 	ap->args.end = fuse_writepage_end;
2067 	wpa->inode = inode;
2068 
2069 	inc_wb_stat(&inode_to_bdi(inode)->wb, WB_WRITEBACK);
2070 	inc_node_page_state(tmp_page, NR_WRITEBACK_TEMP);
2071 
2072 	spin_lock(&fi->lock);
2073 	tree_insert(&fi->writepages, wpa);
2074 	list_add_tail(&wpa->queue_entry, &fi->queued_writes);
2075 	fuse_flush_writepages(inode);
2076 	spin_unlock(&fi->lock);
2077 
2078 	end_page_writeback(page);
2079 
2080 	return 0;
2081 
2082 err_nofile:
2083 	__free_page(tmp_page);
2084 err_free:
2085 	kfree(wpa);
2086 err:
2087 	mapping_set_error(page->mapping, error);
2088 	end_page_writeback(page);
2089 	return error;
2090 }
2091 
fuse_writepage(struct page * page,struct writeback_control * wbc)2092 static int fuse_writepage(struct page *page, struct writeback_control *wbc)
2093 {
2094 	struct fuse_conn *fc = get_fuse_conn(page->mapping->host);
2095 	int err;
2096 
2097 	if (fuse_page_is_writeback(page->mapping->host, page->index)) {
2098 		/*
2099 		 * ->writepages() should be called for sync() and friends.  We
2100 		 * should only get here on direct reclaim and then we are
2101 		 * allowed to skip a page which is already in flight
2102 		 */
2103 		WARN_ON(wbc->sync_mode == WB_SYNC_ALL);
2104 
2105 		redirty_page_for_writepage(wbc, page);
2106 		unlock_page(page);
2107 		return 0;
2108 	}
2109 
2110 	if (wbc->sync_mode == WB_SYNC_NONE &&
2111 	    fc->num_background >= fc->congestion_threshold)
2112 		return AOP_WRITEPAGE_ACTIVATE;
2113 
2114 	err = fuse_writepage_locked(page);
2115 	unlock_page(page);
2116 
2117 	return err;
2118 }
2119 
2120 struct fuse_fill_wb_data {
2121 	struct fuse_writepage_args *wpa;
2122 	struct fuse_file *ff;
2123 	struct inode *inode;
2124 	struct page **orig_pages;
2125 	unsigned int max_pages;
2126 };
2127 
fuse_pages_realloc(struct fuse_fill_wb_data * data)2128 static bool fuse_pages_realloc(struct fuse_fill_wb_data *data)
2129 {
2130 	struct fuse_args_pages *ap = &data->wpa->ia.ap;
2131 	struct fuse_conn *fc = get_fuse_conn(data->inode);
2132 	struct page **pages;
2133 	struct fuse_page_desc *descs;
2134 	unsigned int npages = min_t(unsigned int,
2135 				    max_t(unsigned int, data->max_pages * 2,
2136 					  FUSE_DEFAULT_MAX_PAGES_PER_REQ),
2137 				    fc->max_pages);
2138 	WARN_ON(npages <= data->max_pages);
2139 
2140 	pages = fuse_pages_alloc(npages, GFP_NOFS, &descs);
2141 	if (!pages)
2142 		return false;
2143 
2144 	memcpy(pages, ap->pages, sizeof(struct page *) * ap->num_pages);
2145 	memcpy(descs, ap->descs, sizeof(struct fuse_page_desc) * ap->num_pages);
2146 	kfree(ap->pages);
2147 	ap->pages = pages;
2148 	ap->descs = descs;
2149 	data->max_pages = npages;
2150 
2151 	return true;
2152 }
2153 
fuse_writepages_send(struct fuse_fill_wb_data * data)2154 static void fuse_writepages_send(struct fuse_fill_wb_data *data)
2155 {
2156 	struct fuse_writepage_args *wpa = data->wpa;
2157 	struct inode *inode = data->inode;
2158 	struct fuse_inode *fi = get_fuse_inode(inode);
2159 	int num_pages = wpa->ia.ap.num_pages;
2160 	int i;
2161 
2162 	wpa->ia.ff = fuse_file_get(data->ff);
2163 	spin_lock(&fi->lock);
2164 	list_add_tail(&wpa->queue_entry, &fi->queued_writes);
2165 	fuse_flush_writepages(inode);
2166 	spin_unlock(&fi->lock);
2167 
2168 	for (i = 0; i < num_pages; i++)
2169 		end_page_writeback(data->orig_pages[i]);
2170 }
2171 
2172 /*
2173  * Check under fi->lock if the page is under writeback, and insert it onto the
2174  * rb_tree if not. Otherwise iterate auxiliary write requests, to see if there's
2175  * one already added for a page at this offset.  If there's none, then insert
2176  * this new request onto the auxiliary list, otherwise reuse the existing one by
2177  * swapping the new temp page with the old one.
2178  */
fuse_writepage_add(struct fuse_writepage_args * new_wpa,struct page * page)2179 static bool fuse_writepage_add(struct fuse_writepage_args *new_wpa,
2180 			       struct page *page)
2181 {
2182 	struct fuse_inode *fi = get_fuse_inode(new_wpa->inode);
2183 	struct fuse_writepage_args *tmp;
2184 	struct fuse_writepage_args *old_wpa;
2185 	struct fuse_args_pages *new_ap = &new_wpa->ia.ap;
2186 
2187 	WARN_ON(new_ap->num_pages != 0);
2188 	new_ap->num_pages = 1;
2189 
2190 	spin_lock(&fi->lock);
2191 	old_wpa = fuse_insert_writeback(&fi->writepages, new_wpa);
2192 	if (!old_wpa) {
2193 		spin_unlock(&fi->lock);
2194 		return true;
2195 	}
2196 
2197 	for (tmp = old_wpa->next; tmp; tmp = tmp->next) {
2198 		pgoff_t curr_index;
2199 
2200 		WARN_ON(tmp->inode != new_wpa->inode);
2201 		curr_index = tmp->ia.write.in.offset >> PAGE_SHIFT;
2202 		if (curr_index == page->index) {
2203 			WARN_ON(tmp->ia.ap.num_pages != 1);
2204 			swap(tmp->ia.ap.pages[0], new_ap->pages[0]);
2205 			break;
2206 		}
2207 	}
2208 
2209 	if (!tmp) {
2210 		new_wpa->next = old_wpa->next;
2211 		old_wpa->next = new_wpa;
2212 	}
2213 
2214 	spin_unlock(&fi->lock);
2215 
2216 	if (tmp) {
2217 		struct backing_dev_info *bdi = inode_to_bdi(new_wpa->inode);
2218 
2219 		dec_wb_stat(&bdi->wb, WB_WRITEBACK);
2220 		dec_node_page_state(new_ap->pages[0], NR_WRITEBACK_TEMP);
2221 		wb_writeout_inc(&bdi->wb);
2222 		fuse_writepage_free(new_wpa);
2223 	}
2224 
2225 	return false;
2226 }
2227 
fuse_writepage_need_send(struct fuse_conn * fc,struct page * page,struct fuse_args_pages * ap,struct fuse_fill_wb_data * data)2228 static bool fuse_writepage_need_send(struct fuse_conn *fc, struct page *page,
2229 				     struct fuse_args_pages *ap,
2230 				     struct fuse_fill_wb_data *data)
2231 {
2232 	WARN_ON(!ap->num_pages);
2233 
2234 	/*
2235 	 * Being under writeback is unlikely but possible.  For example direct
2236 	 * read to an mmaped fuse file will set the page dirty twice; once when
2237 	 * the pages are faulted with get_user_pages(), and then after the read
2238 	 * completed.
2239 	 */
2240 	if (fuse_page_is_writeback(data->inode, page->index))
2241 		return true;
2242 
2243 	/* Reached max pages */
2244 	if (ap->num_pages == fc->max_pages)
2245 		return true;
2246 
2247 	/* Reached max write bytes */
2248 	if ((ap->num_pages + 1) * PAGE_SIZE > fc->max_write)
2249 		return true;
2250 
2251 	/* Discontinuity */
2252 	if (data->orig_pages[ap->num_pages - 1]->index + 1 != page->index)
2253 		return true;
2254 
2255 	/* Need to grow the pages array?  If so, did the expansion fail? */
2256 	if (ap->num_pages == data->max_pages && !fuse_pages_realloc(data))
2257 		return true;
2258 
2259 	return false;
2260 }
2261 
fuse_writepages_fill(struct page * page,struct writeback_control * wbc,void * _data)2262 static int fuse_writepages_fill(struct page *page,
2263 		struct writeback_control *wbc, void *_data)
2264 {
2265 	struct fuse_fill_wb_data *data = _data;
2266 	struct fuse_writepage_args *wpa = data->wpa;
2267 	struct fuse_args_pages *ap = &wpa->ia.ap;
2268 	struct inode *inode = data->inode;
2269 	struct fuse_inode *fi = get_fuse_inode(inode);
2270 	struct fuse_conn *fc = get_fuse_conn(inode);
2271 	struct page *tmp_page;
2272 	int err;
2273 
2274 	if (!data->ff) {
2275 		err = -EIO;
2276 		data->ff = fuse_write_file_get(fi);
2277 		if (!data->ff)
2278 			goto out_unlock;
2279 	}
2280 
2281 	if (wpa && fuse_writepage_need_send(fc, page, ap, data)) {
2282 		fuse_writepages_send(data);
2283 		data->wpa = NULL;
2284 	}
2285 
2286 	err = -ENOMEM;
2287 	tmp_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
2288 	if (!tmp_page)
2289 		goto out_unlock;
2290 
2291 	/*
2292 	 * The page must not be redirtied until the writeout is completed
2293 	 * (i.e. userspace has sent a reply to the write request).  Otherwise
2294 	 * there could be more than one temporary page instance for each real
2295 	 * page.
2296 	 *
2297 	 * This is ensured by holding the page lock in page_mkwrite() while
2298 	 * checking fuse_page_is_writeback().  We already hold the page lock
2299 	 * since clear_page_dirty_for_io() and keep it held until we add the
2300 	 * request to the fi->writepages list and increment ap->num_pages.
2301 	 * After this fuse_page_is_writeback() will indicate that the page is
2302 	 * under writeback, so we can release the page lock.
2303 	 */
2304 	if (data->wpa == NULL) {
2305 		err = -ENOMEM;
2306 		wpa = fuse_writepage_args_alloc();
2307 		if (!wpa) {
2308 			__free_page(tmp_page);
2309 			goto out_unlock;
2310 		}
2311 		fuse_writepage_add_to_bucket(fc, wpa);
2312 
2313 		data->max_pages = 1;
2314 
2315 		ap = &wpa->ia.ap;
2316 		fuse_write_args_fill(&wpa->ia, data->ff, page_offset(page), 0);
2317 		wpa->ia.write.in.write_flags |= FUSE_WRITE_CACHE;
2318 		wpa->next = NULL;
2319 		ap->args.in_pages = true;
2320 		ap->args.end = fuse_writepage_end;
2321 		ap->num_pages = 0;
2322 		wpa->inode = inode;
2323 	}
2324 	set_page_writeback(page);
2325 
2326 	copy_highpage(tmp_page, page);
2327 	ap->pages[ap->num_pages] = tmp_page;
2328 	ap->descs[ap->num_pages].offset = 0;
2329 	ap->descs[ap->num_pages].length = PAGE_SIZE;
2330 	data->orig_pages[ap->num_pages] = page;
2331 
2332 	inc_wb_stat(&inode_to_bdi(inode)->wb, WB_WRITEBACK);
2333 	inc_node_page_state(tmp_page, NR_WRITEBACK_TEMP);
2334 
2335 	err = 0;
2336 	if (data->wpa) {
2337 		/*
2338 		 * Protected by fi->lock against concurrent access by
2339 		 * fuse_page_is_writeback().
2340 		 */
2341 		spin_lock(&fi->lock);
2342 		ap->num_pages++;
2343 		spin_unlock(&fi->lock);
2344 	} else if (fuse_writepage_add(wpa, page)) {
2345 		data->wpa = wpa;
2346 	} else {
2347 		end_page_writeback(page);
2348 	}
2349 out_unlock:
2350 	unlock_page(page);
2351 
2352 	return err;
2353 }
2354 
fuse_writepages(struct address_space * mapping,struct writeback_control * wbc)2355 static int fuse_writepages(struct address_space *mapping,
2356 			   struct writeback_control *wbc)
2357 {
2358 	struct inode *inode = mapping->host;
2359 	struct fuse_conn *fc = get_fuse_conn(inode);
2360 	struct fuse_fill_wb_data data;
2361 	int err;
2362 
2363 	err = -EIO;
2364 	if (fuse_is_bad(inode))
2365 		goto out;
2366 
2367 	if (wbc->sync_mode == WB_SYNC_NONE &&
2368 	    fc->num_background >= fc->congestion_threshold)
2369 		return 0;
2370 
2371 	data.inode = inode;
2372 	data.wpa = NULL;
2373 	data.ff = NULL;
2374 
2375 	err = -ENOMEM;
2376 	data.orig_pages = kcalloc(fc->max_pages,
2377 				  sizeof(struct page *),
2378 				  GFP_NOFS);
2379 	if (!data.orig_pages)
2380 		goto out;
2381 
2382 	err = write_cache_pages(mapping, wbc, fuse_writepages_fill, &data);
2383 	if (data.wpa) {
2384 		WARN_ON(!data.wpa->ia.ap.num_pages);
2385 		fuse_writepages_send(&data);
2386 	}
2387 	if (data.ff)
2388 		fuse_file_put(inode, data.ff, false, false);
2389 
2390 	kfree(data.orig_pages);
2391 out:
2392 	return err;
2393 }
2394 
2395 /*
2396  * It's worthy to make sure that space is reserved on disk for the write,
2397  * but how to implement it without killing performance need more thinking.
2398  */
fuse_write_begin(struct file * file,struct address_space * mapping,loff_t pos,unsigned len,struct page ** pagep,void ** fsdata)2399 static int fuse_write_begin(struct file *file, struct address_space *mapping,
2400 		loff_t pos, unsigned len, struct page **pagep, void **fsdata)
2401 {
2402 	pgoff_t index = pos >> PAGE_SHIFT;
2403 	struct fuse_conn *fc = get_fuse_conn(file_inode(file));
2404 	struct page *page;
2405 	loff_t fsize;
2406 	int err = -ENOMEM;
2407 
2408 	WARN_ON(!fc->writeback_cache);
2409 
2410 	page = grab_cache_page_write_begin(mapping, index);
2411 	if (!page)
2412 		goto error;
2413 
2414 	fuse_wait_on_page_writeback(mapping->host, page->index);
2415 
2416 	if (PageUptodate(page) || len == PAGE_SIZE)
2417 		goto success;
2418 	/*
2419 	 * Check if the start this page comes after the end of file, in which
2420 	 * case the readpage can be optimized away.
2421 	 */
2422 	fsize = i_size_read(mapping->host);
2423 	if (fsize <= (pos & PAGE_MASK)) {
2424 		size_t off = pos & ~PAGE_MASK;
2425 		if (off)
2426 			zero_user_segment(page, 0, off);
2427 		goto success;
2428 	}
2429 	err = fuse_do_readpage(file, page);
2430 	if (err)
2431 		goto cleanup;
2432 success:
2433 	*pagep = page;
2434 	return 0;
2435 
2436 cleanup:
2437 	unlock_page(page);
2438 	put_page(page);
2439 error:
2440 	return err;
2441 }
2442 
fuse_write_end(struct file * file,struct address_space * mapping,loff_t pos,unsigned len,unsigned copied,struct page * page,void * fsdata)2443 static int fuse_write_end(struct file *file, struct address_space *mapping,
2444 		loff_t pos, unsigned len, unsigned copied,
2445 		struct page *page, void *fsdata)
2446 {
2447 	struct inode *inode = page->mapping->host;
2448 
2449 	/* Haven't copied anything?  Skip zeroing, size extending, dirtying. */
2450 	if (!copied)
2451 		goto unlock;
2452 
2453 	pos += copied;
2454 	if (!PageUptodate(page)) {
2455 		/* Zero any unwritten bytes at the end of the page */
2456 		size_t endoff = pos & ~PAGE_MASK;
2457 		if (endoff)
2458 			zero_user_segment(page, endoff, PAGE_SIZE);
2459 		SetPageUptodate(page);
2460 	}
2461 
2462 	if (pos > inode->i_size)
2463 		i_size_write(inode, pos);
2464 
2465 	set_page_dirty(page);
2466 
2467 unlock:
2468 	unlock_page(page);
2469 	put_page(page);
2470 
2471 	return copied;
2472 }
2473 
fuse_launder_folio(struct folio * folio)2474 static int fuse_launder_folio(struct folio *folio)
2475 {
2476 	int err = 0;
2477 	if (folio_clear_dirty_for_io(folio)) {
2478 		struct inode *inode = folio->mapping->host;
2479 
2480 		/* Serialize with pending writeback for the same page */
2481 		fuse_wait_on_page_writeback(inode, folio->index);
2482 		err = fuse_writepage_locked(&folio->page);
2483 		if (!err)
2484 			fuse_wait_on_page_writeback(inode, folio->index);
2485 	}
2486 	return err;
2487 }
2488 
2489 /*
2490  * Write back dirty data/metadata now (there may not be any suitable
2491  * open files later for data)
2492  */
fuse_vma_close(struct vm_area_struct * vma)2493 static void fuse_vma_close(struct vm_area_struct *vma)
2494 {
2495 	int err;
2496 
2497 	err = write_inode_now(vma->vm_file->f_mapping->host, 1);
2498 	mapping_set_error(vma->vm_file->f_mapping, err);
2499 }
2500 
2501 /*
2502  * Wait for writeback against this page to complete before allowing it
2503  * to be marked dirty again, and hence written back again, possibly
2504  * before the previous writepage completed.
2505  *
2506  * Block here, instead of in ->writepage(), so that the userspace fs
2507  * can only block processes actually operating on the filesystem.
2508  *
2509  * Otherwise unprivileged userspace fs would be able to block
2510  * unrelated:
2511  *
2512  * - page migration
2513  * - sync(2)
2514  * - try_to_free_pages() with order > PAGE_ALLOC_COSTLY_ORDER
2515  */
fuse_page_mkwrite(struct vm_fault * vmf)2516 static vm_fault_t fuse_page_mkwrite(struct vm_fault *vmf)
2517 {
2518 	struct page *page = vmf->page;
2519 	struct inode *inode = file_inode(vmf->vma->vm_file);
2520 
2521 	file_update_time(vmf->vma->vm_file);
2522 	lock_page(page);
2523 	if (page->mapping != inode->i_mapping) {
2524 		unlock_page(page);
2525 		return VM_FAULT_NOPAGE;
2526 	}
2527 
2528 	fuse_wait_on_page_writeback(inode, page->index);
2529 	return VM_FAULT_LOCKED;
2530 }
2531 
2532 static const struct vm_operations_struct fuse_file_vm_ops = {
2533 	.close		= fuse_vma_close,
2534 	.fault		= filemap_fault,
2535 	.map_pages	= filemap_map_pages,
2536 	.page_mkwrite	= fuse_page_mkwrite,
2537 };
2538 
fuse_file_mmap(struct file * file,struct vm_area_struct * vma)2539 static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
2540 {
2541 	struct fuse_file *ff = file->private_data;
2542 
2543 	/* DAX mmap is superior to direct_io mmap */
2544 	if (FUSE_IS_DAX(file_inode(file)))
2545 		return fuse_dax_mmap(file, vma);
2546 
2547 #ifdef CONFIG_FUSE_BPF
2548 	/* TODO - this is simply passthrough, not a proper BPF filter */
2549 	if (ff->backing_file)
2550 		return fuse_backing_mmap(file, vma);
2551 #endif
2552 
2553 	if (ff->passthrough.filp)
2554 		return fuse_passthrough_mmap(file, vma);
2555 
2556 	if (ff->open_flags & FOPEN_DIRECT_IO) {
2557 		/* Can't provide the coherency needed for MAP_SHARED */
2558 		if (vma->vm_flags & VM_MAYSHARE)
2559 			return -ENODEV;
2560 
2561 		invalidate_inode_pages2(file->f_mapping);
2562 
2563 		return generic_file_mmap(file, vma);
2564 	}
2565 
2566 	if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
2567 		fuse_link_write_file(file);
2568 
2569 	file_accessed(file);
2570 	vma->vm_ops = &fuse_file_vm_ops;
2571 	return 0;
2572 }
2573 
convert_fuse_file_lock(struct fuse_conn * fc,const struct fuse_file_lock * ffl,struct file_lock * fl)2574 static int convert_fuse_file_lock(struct fuse_conn *fc,
2575 				  const struct fuse_file_lock *ffl,
2576 				  struct file_lock *fl)
2577 {
2578 	switch (ffl->type) {
2579 	case F_UNLCK:
2580 		break;
2581 
2582 	case F_RDLCK:
2583 	case F_WRLCK:
2584 		if (ffl->start > OFFSET_MAX || ffl->end > OFFSET_MAX ||
2585 		    ffl->end < ffl->start)
2586 			return -EIO;
2587 
2588 		fl->fl_start = ffl->start;
2589 		fl->fl_end = ffl->end;
2590 
2591 		/*
2592 		 * Convert pid into init's pid namespace.  The locks API will
2593 		 * translate it into the caller's pid namespace.
2594 		 */
2595 		rcu_read_lock();
2596 		fl->fl_pid = pid_nr_ns(find_pid_ns(ffl->pid, fc->pid_ns), &init_pid_ns);
2597 		rcu_read_unlock();
2598 		break;
2599 
2600 	default:
2601 		return -EIO;
2602 	}
2603 	fl->fl_type = ffl->type;
2604 	return 0;
2605 }
2606 
fuse_lk_fill(struct fuse_args * args,struct file * file,const struct file_lock * fl,int opcode,pid_t pid,int flock,struct fuse_lk_in * inarg)2607 static void fuse_lk_fill(struct fuse_args *args, struct file *file,
2608 			 const struct file_lock *fl, int opcode, pid_t pid,
2609 			 int flock, struct fuse_lk_in *inarg)
2610 {
2611 	struct inode *inode = file_inode(file);
2612 	struct fuse_conn *fc = get_fuse_conn(inode);
2613 	struct fuse_file *ff = file->private_data;
2614 
2615 	memset(inarg, 0, sizeof(*inarg));
2616 	inarg->fh = ff->fh;
2617 	inarg->owner = fuse_lock_owner_id(fc, fl->fl_owner);
2618 	inarg->lk.start = fl->fl_start;
2619 	inarg->lk.end = fl->fl_end;
2620 	inarg->lk.type = fl->fl_type;
2621 	inarg->lk.pid = pid;
2622 	if (flock)
2623 		inarg->lk_flags |= FUSE_LK_FLOCK;
2624 	args->opcode = opcode;
2625 	args->nodeid = get_node_id(inode);
2626 	args->in_numargs = 1;
2627 	args->in_args[0].size = sizeof(*inarg);
2628 	args->in_args[0].value = inarg;
2629 }
2630 
fuse_getlk(struct file * file,struct file_lock * fl)2631 static int fuse_getlk(struct file *file, struct file_lock *fl)
2632 {
2633 	struct inode *inode = file_inode(file);
2634 	struct fuse_mount *fm = get_fuse_mount(inode);
2635 	FUSE_ARGS(args);
2636 	struct fuse_lk_in inarg;
2637 	struct fuse_lk_out outarg;
2638 	int err;
2639 
2640 	fuse_lk_fill(&args, file, fl, FUSE_GETLK, 0, 0, &inarg);
2641 	args.out_numargs = 1;
2642 	args.out_args[0].size = sizeof(outarg);
2643 	args.out_args[0].value = &outarg;
2644 	err = fuse_simple_request(fm, &args);
2645 	if (!err)
2646 		err = convert_fuse_file_lock(fm->fc, &outarg.lk, fl);
2647 
2648 	return err;
2649 }
2650 
fuse_setlk(struct file * file,struct file_lock * fl,int flock)2651 static int fuse_setlk(struct file *file, struct file_lock *fl, int flock)
2652 {
2653 	struct inode *inode = file_inode(file);
2654 	struct fuse_mount *fm = get_fuse_mount(inode);
2655 	FUSE_ARGS(args);
2656 	struct fuse_lk_in inarg;
2657 	int opcode = (fl->fl_flags & FL_SLEEP) ? FUSE_SETLKW : FUSE_SETLK;
2658 	struct pid *pid = fl->fl_type != F_UNLCK ? task_tgid(current) : NULL;
2659 	pid_t pid_nr = pid_nr_ns(pid, fm->fc->pid_ns);
2660 	int err;
2661 
2662 	if (fl->fl_lmops && fl->fl_lmops->lm_grant) {
2663 		/* NLM needs asynchronous locks, which we don't support yet */
2664 		return -ENOLCK;
2665 	}
2666 
2667 	/* Unlock on close is handled by the flush method */
2668 	if ((fl->fl_flags & FL_CLOSE_POSIX) == FL_CLOSE_POSIX)
2669 		return 0;
2670 
2671 	fuse_lk_fill(&args, file, fl, opcode, pid_nr, flock, &inarg);
2672 	err = fuse_simple_request(fm, &args);
2673 
2674 	/* locking is restartable */
2675 	if (err == -EINTR)
2676 		err = -ERESTARTSYS;
2677 
2678 	return err;
2679 }
2680 
fuse_file_lock(struct file * file,int cmd,struct file_lock * fl)2681 static int fuse_file_lock(struct file *file, int cmd, struct file_lock *fl)
2682 {
2683 	struct inode *inode = file_inode(file);
2684 	struct fuse_conn *fc = get_fuse_conn(inode);
2685 	int err;
2686 
2687 	if (cmd == F_CANCELLK) {
2688 		err = 0;
2689 	} else if (cmd == F_GETLK) {
2690 		if (fc->no_lock) {
2691 			posix_test_lock(file, fl);
2692 			err = 0;
2693 		} else
2694 			err = fuse_getlk(file, fl);
2695 	} else {
2696 		if (fc->no_lock)
2697 			err = posix_lock_file(file, fl, NULL);
2698 		else
2699 			err = fuse_setlk(file, fl, 0);
2700 	}
2701 	return err;
2702 }
2703 
fuse_file_flock(struct file * file,int cmd,struct file_lock * fl)2704 static int fuse_file_flock(struct file *file, int cmd, struct file_lock *fl)
2705 {
2706 	struct inode *inode = file_inode(file);
2707 	struct fuse_conn *fc = get_fuse_conn(inode);
2708 	struct fuse_file *ff = file->private_data;
2709 	int err;
2710 
2711 #ifdef CONFIG_FUSE_BPF
2712 	/* TODO - this is simply passthrough, not a proper BPF filter */
2713 	if (ff->backing_file)
2714 		return fuse_file_flock_backing(file, cmd, fl);
2715 #endif
2716 
2717 	if (fc->no_flock) {
2718 		err = locks_lock_file_wait(file, fl);
2719 	} else {
2720 
2721 		/* emulate flock with POSIX locks */
2722 		ff->flock = true;
2723 		err = fuse_setlk(file, fl, 1);
2724 	}
2725 
2726 	return err;
2727 }
2728 
fuse_bmap(struct address_space * mapping,sector_t block)2729 static sector_t fuse_bmap(struct address_space *mapping, sector_t block)
2730 {
2731 	struct inode *inode = mapping->host;
2732 	struct fuse_mount *fm = get_fuse_mount(inode);
2733 	FUSE_ARGS(args);
2734 	struct fuse_bmap_in inarg;
2735 	struct fuse_bmap_out outarg;
2736 	int err;
2737 
2738 	if (!inode->i_sb->s_bdev || fm->fc->no_bmap)
2739 		return 0;
2740 
2741 	memset(&inarg, 0, sizeof(inarg));
2742 	inarg.block = block;
2743 	inarg.blocksize = inode->i_sb->s_blocksize;
2744 	args.opcode = FUSE_BMAP;
2745 	args.nodeid = get_node_id(inode);
2746 	args.in_numargs = 1;
2747 	args.in_args[0].size = sizeof(inarg);
2748 	args.in_args[0].value = &inarg;
2749 	args.out_numargs = 1;
2750 	args.out_args[0].size = sizeof(outarg);
2751 	args.out_args[0].value = &outarg;
2752 	err = fuse_simple_request(fm, &args);
2753 	if (err == -ENOSYS)
2754 		fm->fc->no_bmap = 1;
2755 
2756 	return err ? 0 : outarg.block;
2757 }
2758 
fuse_lseek(struct file * file,loff_t offset,int whence)2759 static loff_t fuse_lseek(struct file *file, loff_t offset, int whence)
2760 {
2761 	struct inode *inode = file->f_mapping->host;
2762 	struct fuse_mount *fm = get_fuse_mount(inode);
2763 	struct fuse_file *ff = file->private_data;
2764 	FUSE_ARGS(args);
2765 	struct fuse_lseek_in inarg = {
2766 		.fh = ff->fh,
2767 		.offset = offset,
2768 		.whence = whence
2769 	};
2770 	struct fuse_lseek_out outarg;
2771 	int err;
2772 
2773 	if (fm->fc->no_lseek)
2774 		goto fallback;
2775 
2776 	args.opcode = FUSE_LSEEK;
2777 	args.nodeid = ff->nodeid;
2778 	args.in_numargs = 1;
2779 	args.in_args[0].size = sizeof(inarg);
2780 	args.in_args[0].value = &inarg;
2781 	args.out_numargs = 1;
2782 	args.out_args[0].size = sizeof(outarg);
2783 	args.out_args[0].value = &outarg;
2784 	err = fuse_simple_request(fm, &args);
2785 	if (err) {
2786 		if (err == -ENOSYS) {
2787 			fm->fc->no_lseek = 1;
2788 			goto fallback;
2789 		}
2790 		return err;
2791 	}
2792 
2793 	return vfs_setpos(file, outarg.offset, inode->i_sb->s_maxbytes);
2794 
2795 fallback:
2796 	err = fuse_update_attributes(inode, file, STATX_SIZE);
2797 	if (!err)
2798 		return generic_file_llseek(file, offset, whence);
2799 	else
2800 		return err;
2801 }
2802 
fuse_file_llseek(struct file * file,loff_t offset,int whence)2803 static loff_t fuse_file_llseek(struct file *file, loff_t offset, int whence)
2804 {
2805 	loff_t retval;
2806 	struct inode *inode = file_inode(file);
2807 #ifdef CONFIG_FUSE_BPF
2808 	struct fuse_err_ret fer;
2809 
2810 	fer = fuse_bpf_backing(inode, struct fuse_lseek_io,
2811 			       fuse_lseek_initialize,
2812 			       fuse_lseek_backing,
2813 			       fuse_lseek_finalize,
2814 			       file, offset, whence);
2815 	if (fer.ret)
2816 		return PTR_ERR(fer.result);
2817 #endif
2818 
2819 	switch (whence) {
2820 	case SEEK_SET:
2821 	case SEEK_CUR:
2822 		 /* No i_mutex protection necessary for SEEK_CUR and SEEK_SET */
2823 		retval = generic_file_llseek(file, offset, whence);
2824 		break;
2825 	case SEEK_END:
2826 		inode_lock(inode);
2827 		retval = fuse_update_attributes(inode, file, STATX_SIZE);
2828 		if (!retval)
2829 			retval = generic_file_llseek(file, offset, whence);
2830 		inode_unlock(inode);
2831 		break;
2832 	case SEEK_HOLE:
2833 	case SEEK_DATA:
2834 		inode_lock(inode);
2835 		retval = fuse_lseek(file, offset, whence);
2836 		inode_unlock(inode);
2837 		break;
2838 	default:
2839 		retval = -EINVAL;
2840 	}
2841 
2842 	return retval;
2843 }
2844 
2845 /*
2846  * All files which have been polled are linked to RB tree
2847  * fuse_conn->polled_files which is indexed by kh.  Walk the tree and
2848  * find the matching one.
2849  */
fuse_find_polled_node(struct fuse_conn * fc,u64 kh,struct rb_node ** parent_out)2850 static struct rb_node **fuse_find_polled_node(struct fuse_conn *fc, u64 kh,
2851 					      struct rb_node **parent_out)
2852 {
2853 	struct rb_node **link = &fc->polled_files.rb_node;
2854 	struct rb_node *last = NULL;
2855 
2856 	while (*link) {
2857 		struct fuse_file *ff;
2858 
2859 		last = *link;
2860 		ff = rb_entry(last, struct fuse_file, polled_node);
2861 
2862 		if (kh < ff->kh)
2863 			link = &last->rb_left;
2864 		else if (kh > ff->kh)
2865 			link = &last->rb_right;
2866 		else
2867 			return link;
2868 	}
2869 
2870 	if (parent_out)
2871 		*parent_out = last;
2872 	return link;
2873 }
2874 
2875 /*
2876  * The file is about to be polled.  Make sure it's on the polled_files
2877  * RB tree.  Note that files once added to the polled_files tree are
2878  * not removed before the file is released.  This is because a file
2879  * polled once is likely to be polled again.
2880  */
fuse_register_polled_file(struct fuse_conn * fc,struct fuse_file * ff)2881 static void fuse_register_polled_file(struct fuse_conn *fc,
2882 				      struct fuse_file *ff)
2883 {
2884 	spin_lock(&fc->lock);
2885 	if (RB_EMPTY_NODE(&ff->polled_node)) {
2886 		struct rb_node **link, *parent;
2887 
2888 		link = fuse_find_polled_node(fc, ff->kh, &parent);
2889 		BUG_ON(*link);
2890 		rb_link_node(&ff->polled_node, parent, link);
2891 		rb_insert_color(&ff->polled_node, &fc->polled_files);
2892 	}
2893 	spin_unlock(&fc->lock);
2894 }
2895 
fuse_file_poll(struct file * file,poll_table * wait)2896 __poll_t fuse_file_poll(struct file *file, poll_table *wait)
2897 {
2898 	struct fuse_file *ff = file->private_data;
2899 	struct fuse_mount *fm = ff->fm;
2900 	struct fuse_poll_in inarg = { .fh = ff->fh, .kh = ff->kh };
2901 	struct fuse_poll_out outarg;
2902 	FUSE_ARGS(args);
2903 	int err;
2904 
2905 	if (fm->fc->no_poll)
2906 		return DEFAULT_POLLMASK;
2907 
2908 	poll_wait(file, &ff->poll_wait, wait);
2909 	inarg.events = mangle_poll(poll_requested_events(wait));
2910 
2911 	/*
2912 	 * Ask for notification iff there's someone waiting for it.
2913 	 * The client may ignore the flag and always notify.
2914 	 */
2915 	if (waitqueue_active(&ff->poll_wait)) {
2916 		inarg.flags |= FUSE_POLL_SCHEDULE_NOTIFY;
2917 		fuse_register_polled_file(fm->fc, ff);
2918 	}
2919 
2920 	args.opcode = FUSE_POLL;
2921 	args.nodeid = ff->nodeid;
2922 	args.in_numargs = 1;
2923 	args.in_args[0].size = sizeof(inarg);
2924 	args.in_args[0].value = &inarg;
2925 	args.out_numargs = 1;
2926 	args.out_args[0].size = sizeof(outarg);
2927 	args.out_args[0].value = &outarg;
2928 	err = fuse_simple_request(fm, &args);
2929 
2930 	if (!err)
2931 		return demangle_poll(outarg.revents);
2932 	if (err == -ENOSYS) {
2933 		fm->fc->no_poll = 1;
2934 		return DEFAULT_POLLMASK;
2935 	}
2936 	return EPOLLERR;
2937 }
2938 EXPORT_SYMBOL_GPL(fuse_file_poll);
2939 
2940 /*
2941  * This is called from fuse_handle_notify() on FUSE_NOTIFY_POLL and
2942  * wakes up the poll waiters.
2943  */
fuse_notify_poll_wakeup(struct fuse_conn * fc,struct fuse_notify_poll_wakeup_out * outarg)2944 int fuse_notify_poll_wakeup(struct fuse_conn *fc,
2945 			    struct fuse_notify_poll_wakeup_out *outarg)
2946 {
2947 	u64 kh = outarg->kh;
2948 	struct rb_node **link;
2949 
2950 	spin_lock(&fc->lock);
2951 
2952 	link = fuse_find_polled_node(fc, kh, NULL);
2953 	if (*link) {
2954 		struct fuse_file *ff;
2955 
2956 		ff = rb_entry(*link, struct fuse_file, polled_node);
2957 		wake_up_interruptible_sync(&ff->poll_wait);
2958 	}
2959 
2960 	spin_unlock(&fc->lock);
2961 	return 0;
2962 }
2963 
fuse_do_truncate(struct file * file)2964 static void fuse_do_truncate(struct file *file)
2965 {
2966 	struct inode *inode = file->f_mapping->host;
2967 	struct iattr attr;
2968 
2969 	attr.ia_valid = ATTR_SIZE;
2970 	attr.ia_size = i_size_read(inode);
2971 
2972 	attr.ia_file = file;
2973 	attr.ia_valid |= ATTR_FILE;
2974 
2975 	fuse_do_setattr(file_dentry(file), &attr, file);
2976 }
2977 
fuse_round_up(struct fuse_conn * fc,loff_t off)2978 static inline loff_t fuse_round_up(struct fuse_conn *fc, loff_t off)
2979 {
2980 	return round_up(off, fc->max_pages << PAGE_SHIFT);
2981 }
2982 
2983 static ssize_t
fuse_direct_IO(struct kiocb * iocb,struct iov_iter * iter)2984 fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
2985 {
2986 	DECLARE_COMPLETION_ONSTACK(wait);
2987 	ssize_t ret = 0;
2988 	struct file *file = iocb->ki_filp;
2989 	struct fuse_file *ff = file->private_data;
2990 	loff_t pos = 0;
2991 	struct inode *inode;
2992 	loff_t i_size;
2993 	size_t count = iov_iter_count(iter), shortened = 0;
2994 	loff_t offset = iocb->ki_pos;
2995 	struct fuse_io_priv *io;
2996 
2997 	pos = offset;
2998 	inode = file->f_mapping->host;
2999 	i_size = i_size_read(inode);
3000 
3001 	if ((iov_iter_rw(iter) == READ) && (offset >= i_size))
3002 		return 0;
3003 
3004 	io = kmalloc(sizeof(struct fuse_io_priv), GFP_KERNEL);
3005 	if (!io)
3006 		return -ENOMEM;
3007 	spin_lock_init(&io->lock);
3008 	kref_init(&io->refcnt);
3009 	io->reqs = 1;
3010 	io->bytes = -1;
3011 	io->size = 0;
3012 	io->offset = offset;
3013 	io->write = (iov_iter_rw(iter) == WRITE);
3014 	io->err = 0;
3015 	/*
3016 	 * By default, we want to optimize all I/Os with async request
3017 	 * submission to the client filesystem if supported.
3018 	 */
3019 	io->async = ff->fm->fc->async_dio;
3020 	io->iocb = iocb;
3021 	io->blocking = is_sync_kiocb(iocb);
3022 
3023 	/* optimization for short read */
3024 	if (io->async && !io->write && offset + count > i_size) {
3025 		iov_iter_truncate(iter, fuse_round_up(ff->fm->fc, i_size - offset));
3026 		shortened = count - iov_iter_count(iter);
3027 		count -= shortened;
3028 	}
3029 
3030 	/*
3031 	 * We cannot asynchronously extend the size of a file.
3032 	 * In such case the aio will behave exactly like sync io.
3033 	 */
3034 	if ((offset + count > i_size) && io->write)
3035 		io->blocking = true;
3036 
3037 	if (io->async && io->blocking) {
3038 		/*
3039 		 * Additional reference to keep io around after
3040 		 * calling fuse_aio_complete()
3041 		 */
3042 		kref_get(&io->refcnt);
3043 		io->done = &wait;
3044 	}
3045 
3046 	if (iov_iter_rw(iter) == WRITE) {
3047 		ret = fuse_direct_io(io, iter, &pos, FUSE_DIO_WRITE);
3048 		fuse_invalidate_attr_mask(inode, FUSE_STATX_MODSIZE);
3049 	} else {
3050 		ret = __fuse_direct_read(io, iter, &pos);
3051 	}
3052 	iov_iter_reexpand(iter, iov_iter_count(iter) + shortened);
3053 
3054 	if (io->async) {
3055 		bool blocking = io->blocking;
3056 
3057 		fuse_aio_complete(io, ret < 0 ? ret : 0, -1);
3058 
3059 		/* we have a non-extending, async request, so return */
3060 		if (!blocking)
3061 			return -EIOCBQUEUED;
3062 
3063 		wait_for_completion(&wait);
3064 		ret = fuse_get_res_by_io(io);
3065 	}
3066 
3067 	kref_put(&io->refcnt, fuse_io_release);
3068 
3069 	if (iov_iter_rw(iter) == WRITE) {
3070 		fuse_write_update_attr(inode, pos, ret);
3071 		if (ret < 0 && offset + count > i_size)
3072 			fuse_do_truncate(file);
3073 	}
3074 
3075 	return ret;
3076 }
3077 
fuse_writeback_range(struct inode * inode,loff_t start,loff_t end)3078 static int fuse_writeback_range(struct inode *inode, loff_t start, loff_t end)
3079 {
3080 	int err = filemap_write_and_wait_range(inode->i_mapping, start, LLONG_MAX);
3081 
3082 	if (!err)
3083 		fuse_sync_writes(inode);
3084 
3085 	return err;
3086 }
3087 
fuse_file_fallocate(struct file * file,int mode,loff_t offset,loff_t length)3088 static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
3089 				loff_t length)
3090 {
3091 	struct fuse_file *ff = file->private_data;
3092 	struct inode *inode = file_inode(file);
3093 	struct fuse_inode *fi = get_fuse_inode(inode);
3094 	struct fuse_mount *fm = ff->fm;
3095 	FUSE_ARGS(args);
3096 	struct fuse_fallocate_in inarg = {
3097 		.fh = ff->fh,
3098 		.offset = offset,
3099 		.length = length,
3100 		.mode = mode
3101 	};
3102 	int err;
3103 	bool block_faults = FUSE_IS_DAX(inode) &&
3104 		(!(mode & FALLOC_FL_KEEP_SIZE) ||
3105 		 (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)));
3106 
3107 #ifdef CONFIG_FUSE_BPF
3108 	struct fuse_err_ret fer;
3109 
3110 	fer = fuse_bpf_backing(inode, struct fuse_fallocate_in,
3111 			       fuse_file_fallocate_initialize,
3112 			       fuse_file_fallocate_backing,
3113 			       fuse_file_fallocate_finalize,
3114 			       file, mode, offset, length);
3115 	if (fer.ret)
3116 		return PTR_ERR(fer.result);
3117 #endif
3118 
3119 	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
3120 		     FALLOC_FL_ZERO_RANGE))
3121 		return -EOPNOTSUPP;
3122 
3123 	if (fm->fc->no_fallocate)
3124 		return -EOPNOTSUPP;
3125 
3126 	inode_lock(inode);
3127 	if (block_faults) {
3128 		filemap_invalidate_lock(inode->i_mapping);
3129 		err = fuse_dax_break_layouts(inode, 0, 0);
3130 		if (err)
3131 			goto out;
3132 	}
3133 
3134 	if (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) {
3135 		loff_t endbyte = offset + length - 1;
3136 
3137 		err = fuse_writeback_range(inode, offset, endbyte);
3138 		if (err)
3139 			goto out;
3140 	}
3141 
3142 	if (!(mode & FALLOC_FL_KEEP_SIZE) &&
3143 	    offset + length > i_size_read(inode)) {
3144 		err = inode_newsize_ok(inode, offset + length);
3145 		if (err)
3146 			goto out;
3147 	}
3148 
3149 	err = file_modified(file);
3150 	if (err)
3151 		goto out;
3152 
3153 	if (!(mode & FALLOC_FL_KEEP_SIZE))
3154 		set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
3155 
3156 	args.opcode = FUSE_FALLOCATE;
3157 	args.nodeid = ff->nodeid;
3158 	args.in_numargs = 1;
3159 	args.in_args[0].size = sizeof(inarg);
3160 	args.in_args[0].value = &inarg;
3161 	err = fuse_simple_request(fm, &args);
3162 	if (err == -ENOSYS) {
3163 		fm->fc->no_fallocate = 1;
3164 		err = -EOPNOTSUPP;
3165 	}
3166 	if (err)
3167 		goto out;
3168 
3169 	/* we could have extended the file */
3170 	if (!(mode & FALLOC_FL_KEEP_SIZE)) {
3171 		if (fuse_write_update_attr(inode, offset + length, length))
3172 			file_update_time(file);
3173 	}
3174 
3175 	if (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
3176 		truncate_pagecache_range(inode, offset, offset + length - 1);
3177 
3178 	fuse_invalidate_attr_mask(inode, FUSE_STATX_MODSIZE);
3179 
3180 out:
3181 	if (!(mode & FALLOC_FL_KEEP_SIZE))
3182 		clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
3183 
3184 	if (block_faults)
3185 		filemap_invalidate_unlock(inode->i_mapping);
3186 
3187 	inode_unlock(inode);
3188 
3189 	fuse_flush_time_update(inode);
3190 
3191 	return err;
3192 }
3193 
__fuse_copy_file_range(struct file * file_in,loff_t pos_in,struct file * file_out,loff_t pos_out,size_t len,unsigned int flags)3194 static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
3195 				      struct file *file_out, loff_t pos_out,
3196 				      size_t len, unsigned int flags)
3197 {
3198 	struct fuse_file *ff_in = file_in->private_data;
3199 	struct fuse_file *ff_out = file_out->private_data;
3200 	struct inode *inode_in = file_inode(file_in);
3201 	struct inode *inode_out = file_inode(file_out);
3202 	struct fuse_inode *fi_out = get_fuse_inode(inode_out);
3203 	struct fuse_mount *fm = ff_in->fm;
3204 	struct fuse_conn *fc = fm->fc;
3205 	FUSE_ARGS(args);
3206 	struct fuse_copy_file_range_in inarg = {
3207 		.fh_in = ff_in->fh,
3208 		.off_in = pos_in,
3209 		.nodeid_out = ff_out->nodeid,
3210 		.fh_out = ff_out->fh,
3211 		.off_out = pos_out,
3212 		.len = len,
3213 		.flags = flags
3214 	};
3215 	struct fuse_write_out outarg;
3216 	ssize_t err;
3217 	/* mark unstable when write-back is not used, and file_out gets
3218 	 * extended */
3219 	bool is_unstable = (!fc->writeback_cache) &&
3220 			   ((pos_out + len) > inode_out->i_size);
3221 
3222 #ifdef CONFIG_FUSE_BPF
3223 	struct fuse_err_ret fer;
3224 
3225 	fer = fuse_bpf_backing(file_in->f_inode, struct fuse_copy_file_range_io,
3226 			       fuse_copy_file_range_initialize,
3227 			       fuse_copy_file_range_backing,
3228 			       fuse_copy_file_range_finalize,
3229 			       file_in, pos_in, file_out, pos_out, len, flags);
3230 	if (fer.ret)
3231 		return PTR_ERR(fer.result);
3232 #endif
3233 
3234 	if (fc->no_copy_file_range)
3235 		return -EOPNOTSUPP;
3236 
3237 	if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
3238 		return -EXDEV;
3239 
3240 	inode_lock(inode_in);
3241 	err = fuse_writeback_range(inode_in, pos_in, pos_in + len - 1);
3242 	inode_unlock(inode_in);
3243 	if (err)
3244 		return err;
3245 
3246 	inode_lock(inode_out);
3247 
3248 	err = file_modified(file_out);
3249 	if (err)
3250 		goto out;
3251 
3252 	/*
3253 	 * Write out dirty pages in the destination file before sending the COPY
3254 	 * request to userspace.  After the request is completed, truncate off
3255 	 * pages (including partial ones) from the cache that have been copied,
3256 	 * since these contain stale data at that point.
3257 	 *
3258 	 * This should be mostly correct, but if the COPY writes to partial
3259 	 * pages (at the start or end) and the parts not covered by the COPY are
3260 	 * written through a memory map after calling fuse_writeback_range(),
3261 	 * then these partial page modifications will be lost on truncation.
3262 	 *
3263 	 * It is unlikely that someone would rely on such mixed style
3264 	 * modifications.  Yet this does give less guarantees than if the
3265 	 * copying was performed with write(2).
3266 	 *
3267 	 * To fix this a mapping->invalidate_lock could be used to prevent new
3268 	 * faults while the copy is ongoing.
3269 	 */
3270 	err = fuse_writeback_range(inode_out, pos_out, pos_out + len - 1);
3271 	if (err)
3272 		goto out;
3273 
3274 	if (is_unstable)
3275 		set_bit(FUSE_I_SIZE_UNSTABLE, &fi_out->state);
3276 
3277 	args.opcode = FUSE_COPY_FILE_RANGE;
3278 	args.nodeid = ff_in->nodeid;
3279 	args.in_numargs = 1;
3280 	args.in_args[0].size = sizeof(inarg);
3281 	args.in_args[0].value = &inarg;
3282 	args.out_numargs = 1;
3283 	args.out_args[0].size = sizeof(outarg);
3284 	args.out_args[0].value = &outarg;
3285 	err = fuse_simple_request(fm, &args);
3286 	if (err == -ENOSYS) {
3287 		fc->no_copy_file_range = 1;
3288 		err = -EOPNOTSUPP;
3289 	}
3290 	if (err)
3291 		goto out;
3292 
3293 	truncate_inode_pages_range(inode_out->i_mapping,
3294 				   ALIGN_DOWN(pos_out, PAGE_SIZE),
3295 				   ALIGN(pos_out + outarg.size, PAGE_SIZE) - 1);
3296 
3297 	file_update_time(file_out);
3298 	fuse_write_update_attr(inode_out, pos_out + outarg.size, outarg.size);
3299 
3300 	err = outarg.size;
3301 out:
3302 	if (is_unstable)
3303 		clear_bit(FUSE_I_SIZE_UNSTABLE, &fi_out->state);
3304 
3305 	inode_unlock(inode_out);
3306 	file_accessed(file_in);
3307 
3308 	fuse_flush_time_update(inode_out);
3309 
3310 	return err;
3311 }
3312 
fuse_copy_file_range(struct file * src_file,loff_t src_off,struct file * dst_file,loff_t dst_off,size_t len,unsigned int flags)3313 static ssize_t fuse_copy_file_range(struct file *src_file, loff_t src_off,
3314 				    struct file *dst_file, loff_t dst_off,
3315 				    size_t len, unsigned int flags)
3316 {
3317 	ssize_t ret;
3318 
3319 	ret = __fuse_copy_file_range(src_file, src_off, dst_file, dst_off,
3320 				     len, flags);
3321 
3322 	if (ret == -EOPNOTSUPP || ret == -EXDEV)
3323 		ret = generic_copy_file_range(src_file, src_off, dst_file,
3324 					      dst_off, len, flags);
3325 	return ret;
3326 }
3327 
3328 static const struct file_operations fuse_file_operations = {
3329 	.llseek		= fuse_file_llseek,
3330 	.read_iter	= fuse_file_read_iter,
3331 	.write_iter	= fuse_file_write_iter,
3332 	.mmap		= fuse_file_mmap,
3333 	.open		= fuse_open,
3334 	.flush		= fuse_flush,
3335 	.release	= fuse_release,
3336 	.fsync		= fuse_fsync,
3337 	.lock		= fuse_file_lock,
3338 	.get_unmapped_area = thp_get_unmapped_area,
3339 	.flock		= fuse_file_flock,
3340 	.splice_read	= generic_file_splice_read,
3341 	.splice_write	= iter_file_splice_write,
3342 	.unlocked_ioctl	= fuse_file_ioctl,
3343 	.compat_ioctl	= fuse_file_compat_ioctl,
3344 	.poll		= fuse_file_poll,
3345 	.fallocate	= fuse_file_fallocate,
3346 	.copy_file_range = fuse_copy_file_range,
3347 };
3348 
3349 static const struct address_space_operations fuse_file_aops  = {
3350 	.read_folio	= fuse_read_folio,
3351 	.readahead	= fuse_readahead,
3352 	.writepage	= fuse_writepage,
3353 	.writepages	= fuse_writepages,
3354 	.launder_folio	= fuse_launder_folio,
3355 	.dirty_folio	= filemap_dirty_folio,
3356 	.bmap		= fuse_bmap,
3357 	.direct_IO	= fuse_direct_IO,
3358 	.write_begin	= fuse_write_begin,
3359 	.write_end	= fuse_write_end,
3360 };
3361 
fuse_init_file_inode(struct inode * inode,unsigned int flags)3362 void fuse_init_file_inode(struct inode *inode, unsigned int flags)
3363 {
3364 	struct fuse_inode *fi = get_fuse_inode(inode);
3365 
3366 	inode->i_fop = &fuse_file_operations;
3367 	inode->i_data.a_ops = &fuse_file_aops;
3368 
3369 	INIT_LIST_HEAD(&fi->write_files);
3370 	INIT_LIST_HEAD(&fi->queued_writes);
3371 	fi->writectr = 0;
3372 	init_waitqueue_head(&fi->page_waitq);
3373 	fi->writepages = RB_ROOT;
3374 
3375 	if (IS_ENABLED(CONFIG_FUSE_DAX))
3376 		fuse_dax_inode_init(inode, flags);
3377 }
3378