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
fuse_use_readdirplus(struct inode * dir,struct dir_context * ctx)16 static 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
fuse_add_dirent_to_cache(struct file * file,struct fuse_dirent * dirent,loff_t pos)32 static 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;
88 unlock:
89 spin_unlock(&fi->rdc.lock);
90 unlock_page(page);
91 put_page(page);
92 }
93
fuse_readdir_cache_end(struct file * file,loff_t pos)94 static 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
fuse_emit(struct file * file,struct dir_context * ctx,struct fuse_dirent * dirent)114 static 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
parse_dirfile(char * buf,size_t nbytes,struct file * file,struct dir_context * ctx)126 static 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
fuse_direntplus_link(struct file * file,struct fuse_direntplus * direntplus,u64 attr_version)150 static int fuse_direntplus_link(struct file *file,
151 struct fuse_direntplus *direntplus,
152 u64 attr_version)
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) {
197 retry:
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,
227 entry_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, entry_attr_timeout(o),
236 attr_version);
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 return PTR_ERR(dentry);
248 }
249 if (fc->readdirplus_auto)
250 set_bit(FUSE_I_INIT_RDPLUS, &get_fuse_inode(inode)->state);
251 fuse_change_entry_timeout(dentry, o);
252
253 dput(dentry);
254 return 0;
255 }
256
fuse_force_forget(struct file * file,u64 nodeid)257 static void fuse_force_forget(struct file *file, u64 nodeid)
258 {
259 struct inode *inode = file_inode(file);
260 struct fuse_mount *fm = get_fuse_mount(inode);
261 struct fuse_forget_in inarg;
262 FUSE_ARGS(args);
263
264 memset(&inarg, 0, sizeof(inarg));
265 inarg.nlookup = 1;
266 args.opcode = FUSE_FORGET;
267 args.nodeid = nodeid;
268 args.in_numargs = 1;
269 args.in_args[0].size = sizeof(inarg);
270 args.in_args[0].value = &inarg;
271 args.force = true;
272 args.noreply = true;
273
274 fuse_simple_request(fm, &args);
275 /* ignore errors */
276 }
277
parse_dirplusfile(char * buf,size_t nbytes,struct file * file,struct dir_context * ctx,u64 attr_version)278 static int parse_dirplusfile(char *buf, size_t nbytes, struct file *file,
279 struct dir_context *ctx, u64 attr_version)
280 {
281 struct fuse_direntplus *direntplus;
282 struct fuse_dirent *dirent;
283 size_t reclen;
284 int over = 0;
285 int ret;
286
287 while (nbytes >= FUSE_NAME_OFFSET_DIRENTPLUS) {
288 direntplus = (struct fuse_direntplus *) buf;
289 dirent = &direntplus->dirent;
290 reclen = FUSE_DIRENTPLUS_SIZE(direntplus);
291
292 if (!dirent->namelen || dirent->namelen > FUSE_NAME_MAX)
293 return -EIO;
294 if (reclen > nbytes)
295 break;
296 if (memchr(dirent->name, '/', dirent->namelen) != NULL)
297 return -EIO;
298
299 if (!over) {
300 /* We fill entries into dstbuf only as much as
301 it can hold. But we still continue iterating
302 over remaining entries to link them. If not,
303 we need to send a FORGET for each of those
304 which we did not link.
305 */
306 over = !fuse_emit(file, ctx, dirent);
307 if (!over)
308 ctx->pos = dirent->off;
309 }
310
311 buf += reclen;
312 nbytes -= reclen;
313
314 ret = fuse_direntplus_link(file, direntplus, attr_version);
315 if (ret)
316 fuse_force_forget(file, direntplus->entry_out.nodeid);
317 }
318
319 return 0;
320 }
321
fuse_readdir_uncached(struct file * file,struct dir_context * ctx)322 static int fuse_readdir_uncached(struct file *file, struct dir_context *ctx)
323 {
324 int plus;
325 ssize_t res;
326 struct page *page;
327 struct inode *inode = file_inode(file);
328 struct fuse_mount *fm = get_fuse_mount(inode);
329 struct fuse_io_args ia = {};
330 struct fuse_args_pages *ap = &ia.ap;
331 struct fuse_page_desc desc = { .length = PAGE_SIZE };
332 u64 attr_version = 0;
333 bool locked;
334
335 page = alloc_page(GFP_KERNEL);
336 if (!page)
337 return -ENOMEM;
338
339 plus = fuse_use_readdirplus(inode, ctx);
340 ap->args.out_pages = true;
341 ap->num_pages = 1;
342 ap->pages = &page;
343 ap->descs = &desc;
344 if (plus) {
345 attr_version = fuse_get_attr_version(fm->fc);
346 fuse_read_args_fill(&ia, file, ctx->pos, PAGE_SIZE,
347 FUSE_READDIRPLUS);
348 } else {
349 fuse_read_args_fill(&ia, file, ctx->pos, PAGE_SIZE,
350 FUSE_READDIR);
351 }
352 locked = fuse_lock_inode(inode);
353 res = fuse_simple_request(fm, &ap->args);
354 fuse_unlock_inode(inode, locked);
355 if (res >= 0) {
356 if (!res) {
357 struct fuse_file *ff = file->private_data;
358
359 if (ff->open_flags & FOPEN_CACHE_DIR)
360 fuse_readdir_cache_end(file, ctx->pos);
361 } else if (plus) {
362 res = parse_dirplusfile(page_address(page), res,
363 file, ctx, attr_version);
364 } else {
365 res = parse_dirfile(page_address(page), res, file,
366 ctx);
367 }
368 }
369
370 __free_page(page);
371 fuse_invalidate_atime(inode);
372 return res;
373 }
374
375 enum fuse_parse_result {
376 FOUND_ERR = -1,
377 FOUND_NONE = 0,
378 FOUND_SOME,
379 FOUND_ALL,
380 };
381
fuse_parse_cache(struct fuse_file * ff,void * addr,unsigned int size,struct dir_context * ctx)382 static enum fuse_parse_result fuse_parse_cache(struct fuse_file *ff,
383 void *addr, unsigned int size,
384 struct dir_context *ctx)
385 {
386 unsigned int offset = ff->readdir.cache_off & ~PAGE_MASK;
387 enum fuse_parse_result res = FOUND_NONE;
388
389 WARN_ON(offset >= size);
390
391 for (;;) {
392 struct fuse_dirent *dirent = addr + offset;
393 unsigned int nbytes = size - offset;
394 size_t reclen;
395
396 if (nbytes < FUSE_NAME_OFFSET || !dirent->namelen)
397 break;
398
399 reclen = FUSE_DIRENT_SIZE(dirent); /* derefs ->namelen */
400
401 if (WARN_ON(dirent->namelen > FUSE_NAME_MAX))
402 return FOUND_ERR;
403 if (WARN_ON(reclen > nbytes))
404 return FOUND_ERR;
405 if (WARN_ON(memchr(dirent->name, '/', dirent->namelen) != NULL))
406 return FOUND_ERR;
407
408 if (ff->readdir.pos == ctx->pos) {
409 res = FOUND_SOME;
410 if (!dir_emit(ctx, dirent->name, dirent->namelen,
411 dirent->ino, dirent->type))
412 return FOUND_ALL;
413 ctx->pos = dirent->off;
414 }
415 ff->readdir.pos = dirent->off;
416 ff->readdir.cache_off += reclen;
417
418 offset += reclen;
419 }
420
421 return res;
422 }
423
fuse_rdc_reset(struct inode * inode)424 static void fuse_rdc_reset(struct inode *inode)
425 {
426 struct fuse_inode *fi = get_fuse_inode(inode);
427
428 fi->rdc.cached = false;
429 fi->rdc.version++;
430 fi->rdc.size = 0;
431 fi->rdc.pos = 0;
432 }
433
434 #define UNCACHED 1
435
fuse_readdir_cached(struct file * file,struct dir_context * ctx)436 static int fuse_readdir_cached(struct file *file, struct dir_context *ctx)
437 {
438 struct fuse_file *ff = file->private_data;
439 struct inode *inode = file_inode(file);
440 struct fuse_conn *fc = get_fuse_conn(inode);
441 struct fuse_inode *fi = get_fuse_inode(inode);
442 enum fuse_parse_result res;
443 pgoff_t index;
444 unsigned int size;
445 struct page *page;
446 void *addr;
447
448 /* Seeked? If so, reset the cache stream */
449 if (ff->readdir.pos != ctx->pos) {
450 ff->readdir.pos = 0;
451 ff->readdir.cache_off = 0;
452 }
453
454 /*
455 * We're just about to start reading into the cache or reading the
456 * cache; both cases require an up-to-date mtime value.
457 */
458 if (!ctx->pos && fc->auto_inval_data) {
459 int err = fuse_update_attributes(inode, file, STATX_MTIME);
460
461 if (err)
462 return err;
463 }
464
465 retry:
466 spin_lock(&fi->rdc.lock);
467 retry_locked:
468 if (!fi->rdc.cached) {
469 /* Starting cache? Set cache mtime. */
470 if (!ctx->pos && !fi->rdc.size) {
471 fi->rdc.mtime = inode->i_mtime;
472 fi->rdc.iversion = inode_query_iversion(inode);
473 }
474 spin_unlock(&fi->rdc.lock);
475 return UNCACHED;
476 }
477 /*
478 * When at the beginning of the directory (i.e. just after opendir(3) or
479 * rewinddir(3)), then need to check whether directory contents have
480 * changed, and reset the cache if so.
481 */
482 if (!ctx->pos) {
483 if (inode_peek_iversion(inode) != fi->rdc.iversion ||
484 !timespec64_equal(&fi->rdc.mtime, &inode->i_mtime)) {
485 fuse_rdc_reset(inode);
486 goto retry_locked;
487 }
488 }
489
490 /*
491 * If cache version changed since the last getdents() call, then reset
492 * the cache stream.
493 */
494 if (ff->readdir.version != fi->rdc.version) {
495 ff->readdir.pos = 0;
496 ff->readdir.cache_off = 0;
497 }
498 /*
499 * If at the beginning of the cache, than reset version to
500 * current.
501 */
502 if (ff->readdir.pos == 0)
503 ff->readdir.version = fi->rdc.version;
504
505 WARN_ON(fi->rdc.size < ff->readdir.cache_off);
506
507 index = ff->readdir.cache_off >> PAGE_SHIFT;
508
509 if (index == (fi->rdc.size >> PAGE_SHIFT))
510 size = fi->rdc.size & ~PAGE_MASK;
511 else
512 size = PAGE_SIZE;
513 spin_unlock(&fi->rdc.lock);
514
515 /* EOF? */
516 if ((ff->readdir.cache_off & ~PAGE_MASK) == size)
517 return 0;
518
519 page = find_get_page_flags(file->f_mapping, index,
520 FGP_ACCESSED | FGP_LOCK);
521 /* Page gone missing, then re-added to cache, but not initialized? */
522 if (page && !PageUptodate(page)) {
523 unlock_page(page);
524 put_page(page);
525 page = NULL;
526 }
527 spin_lock(&fi->rdc.lock);
528 if (!page) {
529 /*
530 * Uh-oh: page gone missing, cache is useless
531 */
532 if (fi->rdc.version == ff->readdir.version)
533 fuse_rdc_reset(inode);
534 goto retry_locked;
535 }
536
537 /* Make sure it's still the same version after getting the page. */
538 if (ff->readdir.version != fi->rdc.version) {
539 spin_unlock(&fi->rdc.lock);
540 unlock_page(page);
541 put_page(page);
542 goto retry;
543 }
544 spin_unlock(&fi->rdc.lock);
545
546 /*
547 * Contents of the page are now protected against changing by holding
548 * the page lock.
549 */
550 addr = kmap(page);
551 res = fuse_parse_cache(ff, addr, size, ctx);
552 kunmap(page);
553 unlock_page(page);
554 put_page(page);
555
556 if (res == FOUND_ERR)
557 return -EIO;
558
559 if (res == FOUND_ALL)
560 return 0;
561
562 if (size == PAGE_SIZE) {
563 /* We hit end of page: skip to next page. */
564 ff->readdir.cache_off = ALIGN(ff->readdir.cache_off, PAGE_SIZE);
565 goto retry;
566 }
567
568 /*
569 * End of cache reached. If found position, then we are done, otherwise
570 * need to fall back to uncached, since the position we were looking for
571 * wasn't in the cache.
572 */
573 return res == FOUND_SOME ? 0 : UNCACHED;
574 }
575
fuse_readdir(struct file * file,struct dir_context * ctx)576 int fuse_readdir(struct file *file, struct dir_context *ctx)
577 {
578 struct fuse_file *ff = file->private_data;
579 struct inode *inode = file_inode(file);
580 int err;
581
582 if (fuse_is_bad(inode))
583 return -EIO;
584
585 mutex_lock(&ff->readdir.lock);
586
587 err = UNCACHED;
588 if (ff->open_flags & FOPEN_CACHE_DIR)
589 err = fuse_readdir_cached(file, ctx);
590 if (err == UNCACHED)
591 err = fuse_readdir_uncached(file, ctx);
592
593 mutex_unlock(&ff->readdir.lock);
594
595 return err;
596 }
597
