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1/*
2 FUSE: Filesystem in Userspace
3 Copyright (C) 2001-2018 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
10#include "fuse_i.h"
11#include <linux/iversion.h>
12#include <linux/posix_acl.h>
13#include <linux/pagemap.h>
14#include <linux/highmem.h>
15
16static bool fuse_use_readdirplus(struct inode *dir, struct dir_context *ctx)
17{
18 struct fuse_conn *fc = get_fuse_conn(dir);
19 struct fuse_inode *fi = get_fuse_inode(dir);
20
21 if (!fc->do_readdirplus)
22 return false;
23 if (!fc->readdirplus_auto)
24 return true;
25 if (test_and_clear_bit(FUSE_I_ADVISE_RDPLUS, &fi->state))
26 return true;
27 if (ctx->pos == 0)
28 return true;
29 return false;
30}
31
32static void fuse_add_dirent_to_cache(struct file *file,
33 struct fuse_dirent *dirent, loff_t pos)
34{
35 struct fuse_inode *fi = get_fuse_inode(file_inode(file));
36 size_t reclen = FUSE_DIRENT_SIZE(dirent);
37 pgoff_t index;
38 struct page *page;
39 loff_t size;
40 u64 version;
41 unsigned int offset;
42 void *addr;
43
44 spin_lock(&fi->rdc.lock);
45 /*
46 * Is cache already completed? Or this entry does not go at the end of
47 * cache?
48 */
49 if (fi->rdc.cached || pos != fi->rdc.pos) {
50 spin_unlock(&fi->rdc.lock);
51 return;
52 }
53 version = fi->rdc.version;
54 size = fi->rdc.size;
55 offset = size & ~PAGE_MASK;
56 index = size >> PAGE_SHIFT;
57 /* Dirent doesn't fit in current page? Jump to next page. */
58 if (offset + reclen > PAGE_SIZE) {
59 index++;
60 offset = 0;
61 }
62 spin_unlock(&fi->rdc.lock);
63
64 if (offset) {
65 page = find_lock_page(file->f_mapping, index);
66 } else {
67 page = find_or_create_page(file->f_mapping, index,
68 mapping_gfp_mask(file->f_mapping));
69 }
70 if (!page)
71 return;
72
73 spin_lock(&fi->rdc.lock);
74 /* Raced with another readdir */
75 if (fi->rdc.version != version || fi->rdc.size != size ||
76 WARN_ON(fi->rdc.pos != pos))
77 goto unlock;
78
79 addr = kmap_local_page(page);
80 if (!offset) {
81 clear_page(addr);
82 SetPageUptodate(page);
83 }
84 memcpy(addr + offset, dirent, reclen);
85 kunmap_local(addr);
86 fi->rdc.size = (index << PAGE_SHIFT) + offset + reclen;
87 fi->rdc.pos = dirent->off;
88unlock:
89 spin_unlock(&fi->rdc.lock);
90 unlock_page(page);
91 put_page(page);
92}
93
94static void fuse_readdir_cache_end(struct file *file, loff_t pos)
95{
96 struct fuse_inode *fi = get_fuse_inode(file_inode(file));
97 loff_t end;
98
99 spin_lock(&fi->rdc.lock);
100 /* does cache end position match current position? */
101 if (fi->rdc.pos != pos) {
102 spin_unlock(&fi->rdc.lock);
103 return;
104 }
105
106 fi->rdc.cached = true;
107 end = ALIGN(fi->rdc.size, PAGE_SIZE);
108 spin_unlock(&fi->rdc.lock);
109
110 /* truncate unused tail of cache */
111 truncate_inode_pages(file->f_mapping, end);
112}
113
114static bool fuse_emit(struct file *file, struct dir_context *ctx,
115 struct fuse_dirent *dirent)
116{
117 struct fuse_file *ff = file->private_data;
118
119 if (ff->open_flags & FOPEN_CACHE_DIR)
120 fuse_add_dirent_to_cache(file, dirent, ctx->pos);
121
122 return dir_emit(ctx, dirent->name, dirent->namelen, dirent->ino,
123 dirent->type);
124}
125
126static int parse_dirfile(char *buf, size_t nbytes, struct file *file,
127 struct dir_context *ctx)
128{
129 while (nbytes >= FUSE_NAME_OFFSET) {
130 struct fuse_dirent *dirent = (struct fuse_dirent *) buf;
131 size_t reclen = FUSE_DIRENT_SIZE(dirent);
132 if (!dirent->namelen || dirent->namelen > FUSE_NAME_MAX)
133 return -EIO;
134 if (reclen > nbytes)
135 break;
136 if (memchr(dirent->name, '/', dirent->namelen) != NULL)
137 return -EIO;
138
139 if (!fuse_emit(file, ctx, dirent))
140 break;
141
142 buf += reclen;
143 nbytes -= reclen;
144 ctx->pos = dirent->off;
145 }
146
147 return 0;
148}
149
150static int fuse_direntplus_link(struct file *file,
151 struct fuse_direntplus *direntplus,
152 u64 attr_version, u64 evict_ctr)
153{
154 struct fuse_entry_out *o = &direntplus->entry_out;
155 struct fuse_dirent *dirent = &direntplus->dirent;
156 struct dentry *parent = file->f_path.dentry;
157 struct qstr name = QSTR_INIT(dirent->name, dirent->namelen);
158 struct dentry *dentry;
159 struct dentry *alias;
160 struct inode *dir = d_inode(parent);
161 struct fuse_conn *fc;
162 struct inode *inode;
163 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
164
165 if (!o->nodeid) {
166 /*
167 * Unlike in the case of fuse_lookup, zero nodeid does not mean
168 * ENOENT. Instead, it only means the userspace filesystem did
169 * not want to return attributes/handle for this entry.
170 *
171 * So do nothing.
172 */
173 return 0;
174 }
175
176 if (name.name[0] == '.') {
177 /*
178 * We could potentially refresh the attributes of the directory
179 * and its parent?
180 */
181 if (name.len == 1)
182 return 0;
183 if (name.name[1] == '.' && name.len == 2)
184 return 0;
185 }
186
187 if (invalid_nodeid(o->nodeid))
188 return -EIO;
189 if (fuse_invalid_attr(&o->attr))
190 return -EIO;
191
192 fc = get_fuse_conn(dir);
193
194 name.hash = full_name_hash(parent, name.name, name.len);
195 dentry = d_lookup(parent, &name);
196 if (!dentry) {
197retry:
198 dentry = d_alloc_parallel(parent, &name, &wq);
199 if (IS_ERR(dentry))
200 return PTR_ERR(dentry);
201 }
202 if (!d_in_lookup(dentry)) {
203 struct fuse_inode *fi;
204 inode = d_inode(dentry);
205 if (inode && get_node_id(inode) != o->nodeid)
206 inode = NULL;
207 if (!inode ||
208 fuse_stale_inode(inode, o->generation, &o->attr)) {
209 if (inode)
210 fuse_make_bad(inode);
211 d_invalidate(dentry);
212 dput(dentry);
213 goto retry;
214 }
215 if (fuse_is_bad(inode)) {
216 dput(dentry);
217 return -EIO;
218 }
219
220 fi = get_fuse_inode(inode);
221 spin_lock(&fi->lock);
222 fi->nlookup++;
223 spin_unlock(&fi->lock);
224
225 forget_all_cached_acls(inode);
226 fuse_change_attributes(inode, &o->attr, NULL,
227 ATTR_TIMEOUT(o),
228 attr_version);
229 /*
230 * The other branch comes via fuse_iget()
231 * which bumps nlookup inside
232 */
233 } else {
234 inode = fuse_iget(dir->i_sb, o->nodeid, o->generation,
235 &o->attr, ATTR_TIMEOUT(o),
236 attr_version, evict_ctr);
237 if (!inode)
238 inode = ERR_PTR(-ENOMEM);
239
240 alias = d_splice_alias(inode, dentry);
241 d_lookup_done(dentry);
242 if (alias) {
243 dput(dentry);
244 dentry = alias;
245 }
246 if (IS_ERR(dentry)) {
247 if (!IS_ERR(inode)) {
248 struct fuse_inode *fi = get_fuse_inode(inode);
249
250 spin_lock(&fi->lock);
251 fi->nlookup--;
252 spin_unlock(&fi->lock);
253 }
254 return PTR_ERR(dentry);
255 }
256 }
257 if (fc->readdirplus_auto)
258 set_bit(FUSE_I_INIT_RDPLUS, &get_fuse_inode(inode)->state);
259 fuse_change_entry_timeout(dentry, o);
260
261 dput(dentry);
262 return 0;
263}
264
265static void fuse_force_forget(struct file *file, u64 nodeid)
266{
267 struct inode *inode = file_inode(file);
268 struct fuse_mount *fm = get_fuse_mount(inode);
269 struct fuse_forget_in inarg;
270 FUSE_ARGS(args);
271
272 memset(&inarg, 0, sizeof(inarg));
273 inarg.nlookup = 1;
274 args.opcode = FUSE_FORGET;
275 args.nodeid = nodeid;
276 args.in_numargs = 1;
277 args.in_args[0].size = sizeof(inarg);
278 args.in_args[0].value = &inarg;
279 args.force = true;
280 args.noreply = true;
281
282 fuse_simple_request(fm, &args);
283 /* ignore errors */
284}
285
286static int parse_dirplusfile(char *buf, size_t nbytes, struct file *file,
287 struct dir_context *ctx, u64 attr_version,
288 u64 evict_ctr)
289{
290 struct fuse_direntplus *direntplus;
291 struct fuse_dirent *dirent;
292 size_t reclen;
293 int over = 0;
294 int ret;
295
296 while (nbytes >= FUSE_NAME_OFFSET_DIRENTPLUS) {
297 direntplus = (struct fuse_direntplus *) buf;
298 dirent = &direntplus->dirent;
299 reclen = FUSE_DIRENTPLUS_SIZE(direntplus);
300
301 if (!dirent->namelen || dirent->namelen > FUSE_NAME_MAX)
302 return -EIO;
303 if (reclen > nbytes)
304 break;
305 if (memchr(dirent->name, '/', dirent->namelen) != NULL)
306 return -EIO;
307
308 if (!over) {
309 /* We fill entries into dstbuf only as much as
310 it can hold. But we still continue iterating
311 over remaining entries to link them. If not,
312 we need to send a FORGET for each of those
313 which we did not link.
314 */
315 over = !fuse_emit(file, ctx, dirent);
316 if (!over)
317 ctx->pos = dirent->off;
318 }
319
320 buf += reclen;
321 nbytes -= reclen;
322
323 ret = fuse_direntplus_link(file, direntplus, attr_version, evict_ctr);
324 if (ret)
325 fuse_force_forget(file, direntplus->entry_out.nodeid);
326 }
327
328 return 0;
329}
330
331static int fuse_readdir_uncached(struct file *file, struct dir_context *ctx)
332{
333 int plus;
334 ssize_t res;
335 struct folio *folio;
336 struct inode *inode = file_inode(file);
337 struct fuse_mount *fm = get_fuse_mount(inode);
338 struct fuse_io_args ia = {};
339 struct fuse_args_pages *ap = &ia.ap;
340 struct fuse_folio_desc desc = { .length = PAGE_SIZE };
341 u64 attr_version = 0, evict_ctr = 0;
342 bool locked;
343
344 folio = folio_alloc(GFP_KERNEL, 0);
345 if (!folio)
346 return -ENOMEM;
347
348 plus = fuse_use_readdirplus(inode, ctx);
349 ap->args.out_pages = true;
350 ap->num_folios = 1;
351 ap->folios = &folio;
352 ap->descs = &desc;
353 if (plus) {
354 attr_version = fuse_get_attr_version(fm->fc);
355 evict_ctr = fuse_get_evict_ctr(fm->fc);
356 fuse_read_args_fill(&ia, file, ctx->pos, PAGE_SIZE,
357 FUSE_READDIRPLUS);
358 } else {
359 fuse_read_args_fill(&ia, file, ctx->pos, PAGE_SIZE,
360 FUSE_READDIR);
361 }
362 locked = fuse_lock_inode(inode);
363 res = fuse_simple_request(fm, &ap->args);
364 fuse_unlock_inode(inode, locked);
365 if (res >= 0) {
366 if (!res) {
367 struct fuse_file *ff = file->private_data;
368
369 if (ff->open_flags & FOPEN_CACHE_DIR)
370 fuse_readdir_cache_end(file, ctx->pos);
371 } else if (plus) {
372 res = parse_dirplusfile(folio_address(folio), res,
373 file, ctx, attr_version,
374 evict_ctr);
375 } else {
376 res = parse_dirfile(folio_address(folio), res, file,
377 ctx);
378 }
379 }
380
381 folio_put(folio);
382 fuse_invalidate_atime(inode);
383 return res;
384}
385
386enum fuse_parse_result {
387 FOUND_ERR = -1,
388 FOUND_NONE = 0,
389 FOUND_SOME,
390 FOUND_ALL,
391};
392
393static enum fuse_parse_result fuse_parse_cache(struct fuse_file *ff,
394 void *addr, unsigned int size,
395 struct dir_context *ctx)
396{
397 unsigned int offset = ff->readdir.cache_off & ~PAGE_MASK;
398 enum fuse_parse_result res = FOUND_NONE;
399
400 WARN_ON(offset >= size);
401
402 for (;;) {
403 struct fuse_dirent *dirent = addr + offset;
404 unsigned int nbytes = size - offset;
405 size_t reclen;
406
407 if (nbytes < FUSE_NAME_OFFSET || !dirent->namelen)
408 break;
409
410 reclen = FUSE_DIRENT_SIZE(dirent); /* derefs ->namelen */
411
412 if (WARN_ON(dirent->namelen > FUSE_NAME_MAX))
413 return FOUND_ERR;
414 if (WARN_ON(reclen > nbytes))
415 return FOUND_ERR;
416 if (WARN_ON(memchr(dirent->name, '/', dirent->namelen) != NULL))
417 return FOUND_ERR;
418
419 if (ff->readdir.pos == ctx->pos) {
420 res = FOUND_SOME;
421 if (!dir_emit(ctx, dirent->name, dirent->namelen,
422 dirent->ino, dirent->type))
423 return FOUND_ALL;
424 ctx->pos = dirent->off;
425 }
426 ff->readdir.pos = dirent->off;
427 ff->readdir.cache_off += reclen;
428
429 offset += reclen;
430 }
431
432 return res;
433}
434
435static void fuse_rdc_reset(struct inode *inode)
436{
437 struct fuse_inode *fi = get_fuse_inode(inode);
438
439 fi->rdc.cached = false;
440 fi->rdc.version++;
441 fi->rdc.size = 0;
442 fi->rdc.pos = 0;
443}
444
445#define UNCACHED 1
446
447static int fuse_readdir_cached(struct file *file, struct dir_context *ctx)
448{
449 struct fuse_file *ff = file->private_data;
450 struct inode *inode = file_inode(file);
451 struct fuse_conn *fc = get_fuse_conn(inode);
452 struct fuse_inode *fi = get_fuse_inode(inode);
453 enum fuse_parse_result res;
454 pgoff_t index;
455 unsigned int size;
456 struct page *page;
457 void *addr;
458
459 /* Seeked? If so, reset the cache stream */
460 if (ff->readdir.pos != ctx->pos) {
461 ff->readdir.pos = 0;
462 ff->readdir.cache_off = 0;
463 }
464
465 /*
466 * We're just about to start reading into the cache or reading the
467 * cache; both cases require an up-to-date mtime value.
468 */
469 if (!ctx->pos && fc->auto_inval_data) {
470 int err = fuse_update_attributes(inode, file, STATX_MTIME);
471
472 if (err)
473 return err;
474 }
475
476retry:
477 spin_lock(&fi->rdc.lock);
478retry_locked:
479 if (!fi->rdc.cached) {
480 /* Starting cache? Set cache mtime. */
481 if (!ctx->pos && !fi->rdc.size) {
482 fi->rdc.mtime = inode_get_mtime(inode);
483 fi->rdc.iversion = inode_query_iversion(inode);
484 }
485 spin_unlock(&fi->rdc.lock);
486 return UNCACHED;
487 }
488 /*
489 * When at the beginning of the directory (i.e. just after opendir(3) or
490 * rewinddir(3)), then need to check whether directory contents have
491 * changed, and reset the cache if so.
492 */
493 if (!ctx->pos) {
494 struct timespec64 mtime = inode_get_mtime(inode);
495
496 if (inode_peek_iversion(inode) != fi->rdc.iversion ||
497 !timespec64_equal(&fi->rdc.mtime, &mtime)) {
498 fuse_rdc_reset(inode);
499 goto retry_locked;
500 }
501 }
502
503 /*
504 * If cache version changed since the last getdents() call, then reset
505 * the cache stream.
506 */
507 if (ff->readdir.version != fi->rdc.version) {
508 ff->readdir.pos = 0;
509 ff->readdir.cache_off = 0;
510 }
511 /*
512 * If at the beginning of the cache, than reset version to
513 * current.
514 */
515 if (ff->readdir.pos == 0)
516 ff->readdir.version = fi->rdc.version;
517
518 WARN_ON(fi->rdc.size < ff->readdir.cache_off);
519
520 index = ff->readdir.cache_off >> PAGE_SHIFT;
521
522 if (index == (fi->rdc.size >> PAGE_SHIFT))
523 size = fi->rdc.size & ~PAGE_MASK;
524 else
525 size = PAGE_SIZE;
526 spin_unlock(&fi->rdc.lock);
527
528 /* EOF? */
529 if ((ff->readdir.cache_off & ~PAGE_MASK) == size)
530 return 0;
531
532 page = find_get_page_flags(file->f_mapping, index,
533 FGP_ACCESSED | FGP_LOCK);
534 /* Page gone missing, then re-added to cache, but not initialized? */
535 if (page && !PageUptodate(page)) {
536 unlock_page(page);
537 put_page(page);
538 page = NULL;
539 }
540 spin_lock(&fi->rdc.lock);
541 if (!page) {
542 /*
543 * Uh-oh: page gone missing, cache is useless
544 */
545 if (fi->rdc.version == ff->readdir.version)
546 fuse_rdc_reset(inode);
547 goto retry_locked;
548 }
549
550 /* Make sure it's still the same version after getting the page. */
551 if (ff->readdir.version != fi->rdc.version) {
552 spin_unlock(&fi->rdc.lock);
553 unlock_page(page);
554 put_page(page);
555 goto retry;
556 }
557 spin_unlock(&fi->rdc.lock);
558
559 /*
560 * Contents of the page are now protected against changing by holding
561 * the page lock.
562 */
563 addr = kmap_local_page(page);
564 res = fuse_parse_cache(ff, addr, size, ctx);
565 kunmap_local(addr);
566 unlock_page(page);
567 put_page(page);
568
569 if (res == FOUND_ERR)
570 return -EIO;
571
572 if (res == FOUND_ALL)
573 return 0;
574
575 if (size == PAGE_SIZE) {
576 /* We hit end of page: skip to next page. */
577 ff->readdir.cache_off = ALIGN(ff->readdir.cache_off, PAGE_SIZE);
578 goto retry;
579 }
580
581 /*
582 * End of cache reached. If found position, then we are done, otherwise
583 * need to fall back to uncached, since the position we were looking for
584 * wasn't in the cache.
585 */
586 return res == FOUND_SOME ? 0 : UNCACHED;
587}
588
589int fuse_readdir(struct file *file, struct dir_context *ctx)
590{
591 struct fuse_file *ff = file->private_data;
592 struct inode *inode = file_inode(file);
593 int err;
594
595 if (fuse_is_bad(inode))
596 return -EIO;
597
598 err = UNCACHED;
599 if (ff->open_flags & FOPEN_CACHE_DIR)
600 err = fuse_readdir_cached(file, ctx);
601 if (err == UNCACHED)
602 err = fuse_readdir_uncached(file, ctx);
603
604 return err;
605}