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TOMOYO Linux Cross Reference
Linux/fs/fuse/dir.c

Version: ~ [ linux-5.4-rc7 ] ~ [ linux-5.3.10 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.83 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.153 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.200 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.200 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.76 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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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/pagemap.h>
 12 #include <linux/file.h>
 13 #include <linux/sched.h>
 14 #include <linux/namei.h>
 15 #include <linux/slab.h>
 16 #include <linux/xattr.h>
 17 #include <linux/posix_acl.h>
 18 
 19 static bool fuse_use_readdirplus(struct inode *dir, struct dir_context *ctx)
 20 {
 21         struct fuse_conn *fc = get_fuse_conn(dir);
 22         struct fuse_inode *fi = get_fuse_inode(dir);
 23 
 24         if (!fc->do_readdirplus)
 25                 return false;
 26         if (!fc->readdirplus_auto)
 27                 return true;
 28         if (test_and_clear_bit(FUSE_I_ADVISE_RDPLUS, &fi->state))
 29                 return true;
 30         if (ctx->pos == 0)
 31                 return true;
 32         return false;
 33 }
 34 
 35 static void fuse_advise_use_readdirplus(struct inode *dir)
 36 {
 37         struct fuse_inode *fi = get_fuse_inode(dir);
 38 
 39         set_bit(FUSE_I_ADVISE_RDPLUS, &fi->state);
 40 }
 41 
 42 union fuse_dentry {
 43         u64 time;
 44         struct rcu_head rcu;
 45 };
 46 
 47 static inline void fuse_dentry_settime(struct dentry *entry, u64 time)
 48 {
 49         ((union fuse_dentry *) entry->d_fsdata)->time = time;
 50 }
 51 
 52 static inline u64 fuse_dentry_time(struct dentry *entry)
 53 {
 54         return ((union fuse_dentry *) entry->d_fsdata)->time;
 55 }
 56 
 57 /*
 58  * FUSE caches dentries and attributes with separate timeout.  The
 59  * time in jiffies until the dentry/attributes are valid is stored in
 60  * dentry->d_fsdata and fuse_inode->i_time respectively.
 61  */
 62 
 63 /*
 64  * Calculate the time in jiffies until a dentry/attributes are valid
 65  */
 66 static u64 time_to_jiffies(u64 sec, u32 nsec)
 67 {
 68         if (sec || nsec) {
 69                 struct timespec64 ts = {
 70                         sec,
 71                         min_t(u32, nsec, NSEC_PER_SEC - 1)
 72                 };
 73 
 74                 return get_jiffies_64() + timespec64_to_jiffies(&ts);
 75         } else
 76                 return 0;
 77 }
 78 
 79 /*
 80  * Set dentry and possibly attribute timeouts from the lookup/mk*
 81  * replies
 82  */
 83 static void fuse_change_entry_timeout(struct dentry *entry,
 84                                       struct fuse_entry_out *o)
 85 {
 86         fuse_dentry_settime(entry,
 87                 time_to_jiffies(o->entry_valid, o->entry_valid_nsec));
 88 }
 89 
 90 static u64 attr_timeout(struct fuse_attr_out *o)
 91 {
 92         return time_to_jiffies(o->attr_valid, o->attr_valid_nsec);
 93 }
 94 
 95 static u64 entry_attr_timeout(struct fuse_entry_out *o)
 96 {
 97         return time_to_jiffies(o->attr_valid, o->attr_valid_nsec);
 98 }
 99 
100 /*
101  * Mark the attributes as stale, so that at the next call to
102  * ->getattr() they will be fetched from userspace
103  */
104 void fuse_invalidate_attr(struct inode *inode)
105 {
106         get_fuse_inode(inode)->i_time = 0;
107 }
108 
109 /**
110  * Mark the attributes as stale due to an atime change.  Avoid the invalidate if
111  * atime is not used.
112  */
113 void fuse_invalidate_atime(struct inode *inode)
114 {
115         if (!IS_RDONLY(inode))
116                 fuse_invalidate_attr(inode);
117 }
118 
119 /*
120  * Just mark the entry as stale, so that a next attempt to look it up
121  * will result in a new lookup call to userspace
122  *
123  * This is called when a dentry is about to become negative and the
124  * timeout is unknown (unlink, rmdir, rename and in some cases
125  * lookup)
126  */
127 void fuse_invalidate_entry_cache(struct dentry *entry)
128 {
129         fuse_dentry_settime(entry, 0);
130 }
131 
132 /*
133  * Same as fuse_invalidate_entry_cache(), but also try to remove the
134  * dentry from the hash
135  */
136 static void fuse_invalidate_entry(struct dentry *entry)
137 {
138         d_invalidate(entry);
139         fuse_invalidate_entry_cache(entry);
140 }
141 
142 static void fuse_lookup_init(struct fuse_conn *fc, struct fuse_args *args,
143                              u64 nodeid, const struct qstr *name,
144                              struct fuse_entry_out *outarg)
145 {
146         memset(outarg, 0, sizeof(struct fuse_entry_out));
147         args->in.h.opcode = FUSE_LOOKUP;
148         args->in.h.nodeid = nodeid;
149         args->in.numargs = 1;
150         args->in.args[0].size = name->len + 1;
151         args->in.args[0].value = name->name;
152         args->out.numargs = 1;
153         args->out.args[0].size = sizeof(struct fuse_entry_out);
154         args->out.args[0].value = outarg;
155 }
156 
157 u64 fuse_get_attr_version(struct fuse_conn *fc)
158 {
159         u64 curr_version;
160 
161         /*
162          * The spin lock isn't actually needed on 64bit archs, but we
163          * don't yet care too much about such optimizations.
164          */
165         spin_lock(&fc->lock);
166         curr_version = fc->attr_version;
167         spin_unlock(&fc->lock);
168 
169         return curr_version;
170 }
171 
172 /*
173  * Check whether the dentry is still valid
174  *
175  * If the entry validity timeout has expired and the dentry is
176  * positive, try to redo the lookup.  If the lookup results in a
177  * different inode, then let the VFS invalidate the dentry and redo
178  * the lookup once more.  If the lookup results in the same inode,
179  * then refresh the attributes, timeouts and mark the dentry valid.
180  */
181 static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags)
182 {
183         struct inode *inode;
184         struct dentry *parent;
185         struct fuse_conn *fc;
186         struct fuse_inode *fi;
187         int ret;
188 
189         inode = d_inode_rcu(entry);
190         if (inode && is_bad_inode(inode))
191                 goto invalid;
192         else if (time_before64(fuse_dentry_time(entry), get_jiffies_64()) ||
193                  (flags & LOOKUP_REVAL)) {
194                 struct fuse_entry_out outarg;
195                 FUSE_ARGS(args);
196                 struct fuse_forget_link *forget;
197                 u64 attr_version;
198 
199                 /* For negative dentries, always do a fresh lookup */
200                 if (!inode)
201                         goto invalid;
202 
203                 ret = -ECHILD;
204                 if (flags & LOOKUP_RCU)
205                         goto out;
206 
207                 fc = get_fuse_conn(inode);
208 
209                 forget = fuse_alloc_forget();
210                 ret = -ENOMEM;
211                 if (!forget)
212                         goto out;
213 
214                 attr_version = fuse_get_attr_version(fc);
215 
216                 parent = dget_parent(entry);
217                 fuse_lookup_init(fc, &args, get_node_id(d_inode(parent)),
218                                  &entry->d_name, &outarg);
219                 ret = fuse_simple_request(fc, &args);
220                 dput(parent);
221                 /* Zero nodeid is same as -ENOENT */
222                 if (!ret && !outarg.nodeid)
223                         ret = -ENOENT;
224                 if (!ret) {
225                         fi = get_fuse_inode(inode);
226                         if (outarg.nodeid != get_node_id(inode)) {
227                                 fuse_queue_forget(fc, forget, outarg.nodeid, 1);
228                                 goto invalid;
229                         }
230                         spin_lock(&fc->lock);
231                         fi->nlookup++;
232                         spin_unlock(&fc->lock);
233                 }
234                 kfree(forget);
235                 if (ret == -ENOMEM)
236                         goto out;
237                 if (ret || (outarg.attr.mode ^ inode->i_mode) & S_IFMT)
238                         goto invalid;
239 
240                 forget_all_cached_acls(inode);
241                 fuse_change_attributes(inode, &outarg.attr,
242                                        entry_attr_timeout(&outarg),
243                                        attr_version);
244                 fuse_change_entry_timeout(entry, &outarg);
245         } else if (inode) {
246                 fi = get_fuse_inode(inode);
247                 if (flags & LOOKUP_RCU) {
248                         if (test_bit(FUSE_I_INIT_RDPLUS, &fi->state))
249                                 return -ECHILD;
250                 } else if (test_and_clear_bit(FUSE_I_INIT_RDPLUS, &fi->state)) {
251                         parent = dget_parent(entry);
252                         fuse_advise_use_readdirplus(d_inode(parent));
253                         dput(parent);
254                 }
255         }
256         ret = 1;
257 out:
258         return ret;
259 
260 invalid:
261         ret = 0;
262         goto out;
263 }
264 
265 static int invalid_nodeid(u64 nodeid)
266 {
267         return !nodeid || nodeid == FUSE_ROOT_ID;
268 }
269 
270 static int fuse_dentry_init(struct dentry *dentry)
271 {
272         dentry->d_fsdata = kzalloc(sizeof(union fuse_dentry), GFP_KERNEL);
273 
274         return dentry->d_fsdata ? 0 : -ENOMEM;
275 }
276 static void fuse_dentry_release(struct dentry *dentry)
277 {
278         union fuse_dentry *fd = dentry->d_fsdata;
279 
280         kfree_rcu(fd, rcu);
281 }
282 
283 const struct dentry_operations fuse_dentry_operations = {
284         .d_revalidate   = fuse_dentry_revalidate,
285         .d_init         = fuse_dentry_init,
286         .d_release      = fuse_dentry_release,
287 };
288 
289 const struct dentry_operations fuse_root_dentry_operations = {
290         .d_init         = fuse_dentry_init,
291         .d_release      = fuse_dentry_release,
292 };
293 
294 int fuse_valid_type(int m)
295 {
296         return S_ISREG(m) || S_ISDIR(m) || S_ISLNK(m) || S_ISCHR(m) ||
297                 S_ISBLK(m) || S_ISFIFO(m) || S_ISSOCK(m);
298 }
299 
300 int fuse_lookup_name(struct super_block *sb, u64 nodeid, const struct qstr *name,
301                      struct fuse_entry_out *outarg, struct inode **inode)
302 {
303         struct fuse_conn *fc = get_fuse_conn_super(sb);
304         FUSE_ARGS(args);
305         struct fuse_forget_link *forget;
306         u64 attr_version;
307         int err;
308 
309         *inode = NULL;
310         err = -ENAMETOOLONG;
311         if (name->len > FUSE_NAME_MAX)
312                 goto out;
313 
314 
315         forget = fuse_alloc_forget();
316         err = -ENOMEM;
317         if (!forget)
318                 goto out;
319 
320         attr_version = fuse_get_attr_version(fc);
321 
322         fuse_lookup_init(fc, &args, nodeid, name, outarg);
323         err = fuse_simple_request(fc, &args);
324         /* Zero nodeid is same as -ENOENT, but with valid timeout */
325         if (err || !outarg->nodeid)
326                 goto out_put_forget;
327 
328         err = -EIO;
329         if (!outarg->nodeid)
330                 goto out_put_forget;
331         if (!fuse_valid_type(outarg->attr.mode))
332                 goto out_put_forget;
333 
334         *inode = fuse_iget(sb, outarg->nodeid, outarg->generation,
335                            &outarg->attr, entry_attr_timeout(outarg),
336                            attr_version);
337         err = -ENOMEM;
338         if (!*inode) {
339                 fuse_queue_forget(fc, forget, outarg->nodeid, 1);
340                 goto out;
341         }
342         err = 0;
343 
344  out_put_forget:
345         kfree(forget);
346  out:
347         return err;
348 }
349 
350 static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry,
351                                   unsigned int flags)
352 {
353         int err;
354         struct fuse_entry_out outarg;
355         struct inode *inode;
356         struct dentry *newent;
357         bool outarg_valid = true;
358 
359         fuse_lock_inode(dir);
360         err = fuse_lookup_name(dir->i_sb, get_node_id(dir), &entry->d_name,
361                                &outarg, &inode);
362         fuse_unlock_inode(dir);
363         if (err == -ENOENT) {
364                 outarg_valid = false;
365                 err = 0;
366         }
367         if (err)
368                 goto out_err;
369 
370         err = -EIO;
371         if (inode && get_node_id(inode) == FUSE_ROOT_ID)
372                 goto out_iput;
373 
374         newent = d_splice_alias(inode, entry);
375         err = PTR_ERR(newent);
376         if (IS_ERR(newent))
377                 goto out_err;
378 
379         entry = newent ? newent : entry;
380         if (outarg_valid)
381                 fuse_change_entry_timeout(entry, &outarg);
382         else
383                 fuse_invalidate_entry_cache(entry);
384 
385         fuse_advise_use_readdirplus(dir);
386         return newent;
387 
388  out_iput:
389         iput(inode);
390  out_err:
391         return ERR_PTR(err);
392 }
393 
394 /*
395  * Atomic create+open operation
396  *
397  * If the filesystem doesn't support this, then fall back to separate
398  * 'mknod' + 'open' requests.
399  */
400 static int fuse_create_open(struct inode *dir, struct dentry *entry,
401                             struct file *file, unsigned flags,
402                             umode_t mode, int *opened)
403 {
404         int err;
405         struct inode *inode;
406         struct fuse_conn *fc = get_fuse_conn(dir);
407         FUSE_ARGS(args);
408         struct fuse_forget_link *forget;
409         struct fuse_create_in inarg;
410         struct fuse_open_out outopen;
411         struct fuse_entry_out outentry;
412         struct fuse_file *ff;
413 
414         /* Userspace expects S_IFREG in create mode */
415         BUG_ON((mode & S_IFMT) != S_IFREG);
416 
417         forget = fuse_alloc_forget();
418         err = -ENOMEM;
419         if (!forget)
420                 goto out_err;
421 
422         err = -ENOMEM;
423         ff = fuse_file_alloc(fc);
424         if (!ff)
425                 goto out_put_forget_req;
426 
427         if (!fc->dont_mask)
428                 mode &= ~current_umask();
429 
430         flags &= ~O_NOCTTY;
431         memset(&inarg, 0, sizeof(inarg));
432         memset(&outentry, 0, sizeof(outentry));
433         inarg.flags = flags;
434         inarg.mode = mode;
435         inarg.umask = current_umask();
436         args.in.h.opcode = FUSE_CREATE;
437         args.in.h.nodeid = get_node_id(dir);
438         args.in.numargs = 2;
439         args.in.args[0].size = sizeof(inarg);
440         args.in.args[0].value = &inarg;
441         args.in.args[1].size = entry->d_name.len + 1;
442         args.in.args[1].value = entry->d_name.name;
443         args.out.numargs = 2;
444         args.out.args[0].size = sizeof(outentry);
445         args.out.args[0].value = &outentry;
446         args.out.args[1].size = sizeof(outopen);
447         args.out.args[1].value = &outopen;
448         err = fuse_simple_request(fc, &args);
449         if (err)
450                 goto out_free_ff;
451 
452         err = -EIO;
453         if (!S_ISREG(outentry.attr.mode) || invalid_nodeid(outentry.nodeid))
454                 goto out_free_ff;
455 
456         ff->fh = outopen.fh;
457         ff->nodeid = outentry.nodeid;
458         ff->open_flags = outopen.open_flags;
459         inode = fuse_iget(dir->i_sb, outentry.nodeid, outentry.generation,
460                           &outentry.attr, entry_attr_timeout(&outentry), 0);
461         if (!inode) {
462                 flags &= ~(O_CREAT | O_EXCL | O_TRUNC);
463                 fuse_sync_release(ff, flags);
464                 fuse_queue_forget(fc, forget, outentry.nodeid, 1);
465                 err = -ENOMEM;
466                 goto out_err;
467         }
468         kfree(forget);
469         d_instantiate(entry, inode);
470         fuse_change_entry_timeout(entry, &outentry);
471         fuse_invalidate_attr(dir);
472         err = finish_open(file, entry, generic_file_open, opened);
473         if (err) {
474                 fuse_sync_release(ff, flags);
475         } else {
476                 file->private_data = ff;
477                 fuse_finish_open(inode, file);
478         }
479         return err;
480 
481 out_free_ff:
482         fuse_file_free(ff);
483 out_put_forget_req:
484         kfree(forget);
485 out_err:
486         return err;
487 }
488 
489 static int fuse_mknod(struct inode *, struct dentry *, umode_t, dev_t);
490 static int fuse_atomic_open(struct inode *dir, struct dentry *entry,
491                             struct file *file, unsigned flags,
492                             umode_t mode, int *opened)
493 {
494         int err;
495         struct fuse_conn *fc = get_fuse_conn(dir);
496         struct dentry *res = NULL;
497 
498         if (d_in_lookup(entry)) {
499                 res = fuse_lookup(dir, entry, 0);
500                 if (IS_ERR(res))
501                         return PTR_ERR(res);
502 
503                 if (res)
504                         entry = res;
505         }
506 
507         if (!(flags & O_CREAT) || d_really_is_positive(entry))
508                 goto no_open;
509 
510         /* Only creates */
511         *opened |= FILE_CREATED;
512 
513         if (fc->no_create)
514                 goto mknod;
515 
516         err = fuse_create_open(dir, entry, file, flags, mode, opened);
517         if (err == -ENOSYS) {
518                 fc->no_create = 1;
519                 goto mknod;
520         }
521 out_dput:
522         dput(res);
523         return err;
524 
525 mknod:
526         err = fuse_mknod(dir, entry, mode, 0);
527         if (err)
528                 goto out_dput;
529 no_open:
530         return finish_no_open(file, res);
531 }
532 
533 /*
534  * Code shared between mknod, mkdir, symlink and link
535  */
536 static int create_new_entry(struct fuse_conn *fc, struct fuse_args *args,
537                             struct inode *dir, struct dentry *entry,
538                             umode_t mode)
539 {
540         struct fuse_entry_out outarg;
541         struct inode *inode;
542         int err;
543         struct fuse_forget_link *forget;
544 
545         forget = fuse_alloc_forget();
546         if (!forget)
547                 return -ENOMEM;
548 
549         memset(&outarg, 0, sizeof(outarg));
550         args->in.h.nodeid = get_node_id(dir);
551         args->out.numargs = 1;
552         args->out.args[0].size = sizeof(outarg);
553         args->out.args[0].value = &outarg;
554         err = fuse_simple_request(fc, args);
555         if (err)
556                 goto out_put_forget_req;
557 
558         err = -EIO;
559         if (invalid_nodeid(outarg.nodeid))
560                 goto out_put_forget_req;
561 
562         if ((outarg.attr.mode ^ mode) & S_IFMT)
563                 goto out_put_forget_req;
564 
565         inode = fuse_iget(dir->i_sb, outarg.nodeid, outarg.generation,
566                           &outarg.attr, entry_attr_timeout(&outarg), 0);
567         if (!inode) {
568                 fuse_queue_forget(fc, forget, outarg.nodeid, 1);
569                 return -ENOMEM;
570         }
571         kfree(forget);
572 
573         err = d_instantiate_no_diralias(entry, inode);
574         if (err)
575                 return err;
576 
577         fuse_change_entry_timeout(entry, &outarg);
578         fuse_invalidate_attr(dir);
579         return 0;
580 
581  out_put_forget_req:
582         kfree(forget);
583         return err;
584 }
585 
586 static int fuse_mknod(struct inode *dir, struct dentry *entry, umode_t mode,
587                       dev_t rdev)
588 {
589         struct fuse_mknod_in inarg;
590         struct fuse_conn *fc = get_fuse_conn(dir);
591         FUSE_ARGS(args);
592 
593         if (!fc->dont_mask)
594                 mode &= ~current_umask();
595 
596         memset(&inarg, 0, sizeof(inarg));
597         inarg.mode = mode;
598         inarg.rdev = new_encode_dev(rdev);
599         inarg.umask = current_umask();
600         args.in.h.opcode = FUSE_MKNOD;
601         args.in.numargs = 2;
602         args.in.args[0].size = sizeof(inarg);
603         args.in.args[0].value = &inarg;
604         args.in.args[1].size = entry->d_name.len + 1;
605         args.in.args[1].value = entry->d_name.name;
606         return create_new_entry(fc, &args, dir, entry, mode);
607 }
608 
609 static int fuse_create(struct inode *dir, struct dentry *entry, umode_t mode,
610                        bool excl)
611 {
612         return fuse_mknod(dir, entry, mode, 0);
613 }
614 
615 static int fuse_mkdir(struct inode *dir, struct dentry *entry, umode_t mode)
616 {
617         struct fuse_mkdir_in inarg;
618         struct fuse_conn *fc = get_fuse_conn(dir);
619         FUSE_ARGS(args);
620 
621         if (!fc->dont_mask)
622                 mode &= ~current_umask();
623 
624         memset(&inarg, 0, sizeof(inarg));
625         inarg.mode = mode;
626         inarg.umask = current_umask();
627         args.in.h.opcode = FUSE_MKDIR;
628         args.in.numargs = 2;
629         args.in.args[0].size = sizeof(inarg);
630         args.in.args[0].value = &inarg;
631         args.in.args[1].size = entry->d_name.len + 1;
632         args.in.args[1].value = entry->d_name.name;
633         return create_new_entry(fc, &args, dir, entry, S_IFDIR);
634 }
635 
636 static int fuse_symlink(struct inode *dir, struct dentry *entry,
637                         const char *link)
638 {
639         struct fuse_conn *fc = get_fuse_conn(dir);
640         unsigned len = strlen(link) + 1;
641         FUSE_ARGS(args);
642 
643         args.in.h.opcode = FUSE_SYMLINK;
644         args.in.numargs = 2;
645         args.in.args[0].size = entry->d_name.len + 1;
646         args.in.args[0].value = entry->d_name.name;
647         args.in.args[1].size = len;
648         args.in.args[1].value = link;
649         return create_new_entry(fc, &args, dir, entry, S_IFLNK);
650 }
651 
652 void fuse_update_ctime(struct inode *inode)
653 {
654         if (!IS_NOCMTIME(inode)) {
655                 inode->i_ctime = current_time(inode);
656                 mark_inode_dirty_sync(inode);
657         }
658 }
659 
660 static int fuse_unlink(struct inode *dir, struct dentry *entry)
661 {
662         int err;
663         struct fuse_conn *fc = get_fuse_conn(dir);
664         FUSE_ARGS(args);
665 
666         args.in.h.opcode = FUSE_UNLINK;
667         args.in.h.nodeid = get_node_id(dir);
668         args.in.numargs = 1;
669         args.in.args[0].size = entry->d_name.len + 1;
670         args.in.args[0].value = entry->d_name.name;
671         err = fuse_simple_request(fc, &args);
672         if (!err) {
673                 struct inode *inode = d_inode(entry);
674                 struct fuse_inode *fi = get_fuse_inode(inode);
675 
676                 spin_lock(&fc->lock);
677                 fi->attr_version = ++fc->attr_version;
678                 /*
679                  * If i_nlink == 0 then unlink doesn't make sense, yet this can
680                  * happen if userspace filesystem is careless.  It would be
681                  * difficult to enforce correct nlink usage so just ignore this
682                  * condition here
683                  */
684                 if (inode->i_nlink > 0)
685                         drop_nlink(inode);
686                 spin_unlock(&fc->lock);
687                 fuse_invalidate_attr(inode);
688                 fuse_invalidate_attr(dir);
689                 fuse_invalidate_entry_cache(entry);
690                 fuse_update_ctime(inode);
691         } else if (err == -EINTR)
692                 fuse_invalidate_entry(entry);
693         return err;
694 }
695 
696 static int fuse_rmdir(struct inode *dir, struct dentry *entry)
697 {
698         int err;
699         struct fuse_conn *fc = get_fuse_conn(dir);
700         FUSE_ARGS(args);
701 
702         args.in.h.opcode = FUSE_RMDIR;
703         args.in.h.nodeid = get_node_id(dir);
704         args.in.numargs = 1;
705         args.in.args[0].size = entry->d_name.len + 1;
706         args.in.args[0].value = entry->d_name.name;
707         err = fuse_simple_request(fc, &args);
708         if (!err) {
709                 clear_nlink(d_inode(entry));
710                 fuse_invalidate_attr(dir);
711                 fuse_invalidate_entry_cache(entry);
712         } else if (err == -EINTR)
713                 fuse_invalidate_entry(entry);
714         return err;
715 }
716 
717 static int fuse_rename_common(struct inode *olddir, struct dentry *oldent,
718                               struct inode *newdir, struct dentry *newent,
719                               unsigned int flags, int opcode, size_t argsize)
720 {
721         int err;
722         struct fuse_rename2_in inarg;
723         struct fuse_conn *fc = get_fuse_conn(olddir);
724         FUSE_ARGS(args);
725 
726         memset(&inarg, 0, argsize);
727         inarg.newdir = get_node_id(newdir);
728         inarg.flags = flags;
729         args.in.h.opcode = opcode;
730         args.in.h.nodeid = get_node_id(olddir);
731         args.in.numargs = 3;
732         args.in.args[0].size = argsize;
733         args.in.args[0].value = &inarg;
734         args.in.args[1].size = oldent->d_name.len + 1;
735         args.in.args[1].value = oldent->d_name.name;
736         args.in.args[2].size = newent->d_name.len + 1;
737         args.in.args[2].value = newent->d_name.name;
738         err = fuse_simple_request(fc, &args);
739         if (!err) {
740                 /* ctime changes */
741                 fuse_invalidate_attr(d_inode(oldent));
742                 fuse_update_ctime(d_inode(oldent));
743 
744                 if (flags & RENAME_EXCHANGE) {
745                         fuse_invalidate_attr(d_inode(newent));
746                         fuse_update_ctime(d_inode(newent));
747                 }
748 
749                 fuse_invalidate_attr(olddir);
750                 if (olddir != newdir)
751                         fuse_invalidate_attr(newdir);
752 
753                 /* newent will end up negative */
754                 if (!(flags & RENAME_EXCHANGE) && d_really_is_positive(newent)) {
755                         fuse_invalidate_attr(d_inode(newent));
756                         fuse_invalidate_entry_cache(newent);
757                         fuse_update_ctime(d_inode(newent));
758                 }
759         } else if (err == -EINTR) {
760                 /* If request was interrupted, DEITY only knows if the
761                    rename actually took place.  If the invalidation
762                    fails (e.g. some process has CWD under the renamed
763                    directory), then there can be inconsistency between
764                    the dcache and the real filesystem.  Tough luck. */
765                 fuse_invalidate_entry(oldent);
766                 if (d_really_is_positive(newent))
767                         fuse_invalidate_entry(newent);
768         }
769 
770         return err;
771 }
772 
773 static int fuse_rename2(struct inode *olddir, struct dentry *oldent,
774                         struct inode *newdir, struct dentry *newent,
775                         unsigned int flags)
776 {
777         struct fuse_conn *fc = get_fuse_conn(olddir);
778         int err;
779 
780         if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
781                 return -EINVAL;
782 
783         if (flags) {
784                 if (fc->no_rename2 || fc->minor < 23)
785                         return -EINVAL;
786 
787                 err = fuse_rename_common(olddir, oldent, newdir, newent, flags,
788                                          FUSE_RENAME2,
789                                          sizeof(struct fuse_rename2_in));
790                 if (err == -ENOSYS) {
791                         fc->no_rename2 = 1;
792                         err = -EINVAL;
793                 }
794         } else {
795                 err = fuse_rename_common(olddir, oldent, newdir, newent, 0,
796                                          FUSE_RENAME,
797                                          sizeof(struct fuse_rename_in));
798         }
799 
800         return err;
801 }
802 
803 static int fuse_link(struct dentry *entry, struct inode *newdir,
804                      struct dentry *newent)
805 {
806         int err;
807         struct fuse_link_in inarg;
808         struct inode *inode = d_inode(entry);
809         struct fuse_conn *fc = get_fuse_conn(inode);
810         FUSE_ARGS(args);
811 
812         memset(&inarg, 0, sizeof(inarg));
813         inarg.oldnodeid = get_node_id(inode);
814         args.in.h.opcode = FUSE_LINK;
815         args.in.numargs = 2;
816         args.in.args[0].size = sizeof(inarg);
817         args.in.args[0].value = &inarg;
818         args.in.args[1].size = newent->d_name.len + 1;
819         args.in.args[1].value = newent->d_name.name;
820         err = create_new_entry(fc, &args, newdir, newent, inode->i_mode);
821         /* Contrary to "normal" filesystems it can happen that link
822            makes two "logical" inodes point to the same "physical"
823            inode.  We invalidate the attributes of the old one, so it
824            will reflect changes in the backing inode (link count,
825            etc.)
826         */
827         if (!err) {
828                 struct fuse_inode *fi = get_fuse_inode(inode);
829 
830                 spin_lock(&fc->lock);
831                 fi->attr_version = ++fc->attr_version;
832                 inc_nlink(inode);
833                 spin_unlock(&fc->lock);
834                 fuse_invalidate_attr(inode);
835                 fuse_update_ctime(inode);
836         } else if (err == -EINTR) {
837                 fuse_invalidate_attr(inode);
838         }
839         return err;
840 }
841 
842 static void fuse_fillattr(struct inode *inode, struct fuse_attr *attr,
843                           struct kstat *stat)
844 {
845         unsigned int blkbits;
846         struct fuse_conn *fc = get_fuse_conn(inode);
847 
848         /* see the comment in fuse_change_attributes() */
849         if (fc->writeback_cache && S_ISREG(inode->i_mode)) {
850                 attr->size = i_size_read(inode);
851                 attr->mtime = inode->i_mtime.tv_sec;
852                 attr->mtimensec = inode->i_mtime.tv_nsec;
853                 attr->ctime = inode->i_ctime.tv_sec;
854                 attr->ctimensec = inode->i_ctime.tv_nsec;
855         }
856 
857         stat->dev = inode->i_sb->s_dev;
858         stat->ino = attr->ino;
859         stat->mode = (inode->i_mode & S_IFMT) | (attr->mode & 07777);
860         stat->nlink = attr->nlink;
861         stat->uid = make_kuid(&init_user_ns, attr->uid);
862         stat->gid = make_kgid(&init_user_ns, attr->gid);
863         stat->rdev = inode->i_rdev;
864         stat->atime.tv_sec = attr->atime;
865         stat->atime.tv_nsec = attr->atimensec;
866         stat->mtime.tv_sec = attr->mtime;
867         stat->mtime.tv_nsec = attr->mtimensec;
868         stat->ctime.tv_sec = attr->ctime;
869         stat->ctime.tv_nsec = attr->ctimensec;
870         stat->size = attr->size;
871         stat->blocks = attr->blocks;
872 
873         if (attr->blksize != 0)
874                 blkbits = ilog2(attr->blksize);
875         else
876                 blkbits = inode->i_sb->s_blocksize_bits;
877 
878         stat->blksize = 1 << blkbits;
879 }
880 
881 static int fuse_do_getattr(struct inode *inode, struct kstat *stat,
882                            struct file *file)
883 {
884         int err;
885         struct fuse_getattr_in inarg;
886         struct fuse_attr_out outarg;
887         struct fuse_conn *fc = get_fuse_conn(inode);
888         FUSE_ARGS(args);
889         u64 attr_version;
890 
891         attr_version = fuse_get_attr_version(fc);
892 
893         memset(&inarg, 0, sizeof(inarg));
894         memset(&outarg, 0, sizeof(outarg));
895         /* Directories have separate file-handle space */
896         if (file && S_ISREG(inode->i_mode)) {
897                 struct fuse_file *ff = file->private_data;
898 
899                 inarg.getattr_flags |= FUSE_GETATTR_FH;
900                 inarg.fh = ff->fh;
901         }
902         args.in.h.opcode = FUSE_GETATTR;
903         args.in.h.nodeid = get_node_id(inode);
904         args.in.numargs = 1;
905         args.in.args[0].size = sizeof(inarg);
906         args.in.args[0].value = &inarg;
907         args.out.numargs = 1;
908         args.out.args[0].size = sizeof(outarg);
909         args.out.args[0].value = &outarg;
910         err = fuse_simple_request(fc, &args);
911         if (!err) {
912                 if ((inode->i_mode ^ outarg.attr.mode) & S_IFMT) {
913                         make_bad_inode(inode);
914                         err = -EIO;
915                 } else {
916                         fuse_change_attributes(inode, &outarg.attr,
917                                                attr_timeout(&outarg),
918                                                attr_version);
919                         if (stat)
920                                 fuse_fillattr(inode, &outarg.attr, stat);
921                 }
922         }
923         return err;
924 }
925 
926 int fuse_update_attributes(struct inode *inode, struct kstat *stat,
927                            struct file *file, bool *refreshed)
928 {
929         struct fuse_inode *fi = get_fuse_inode(inode);
930         int err;
931         bool r;
932 
933         if (time_before64(fi->i_time, get_jiffies_64())) {
934                 r = true;
935                 forget_all_cached_acls(inode);
936                 err = fuse_do_getattr(inode, stat, file);
937         } else {
938                 r = false;
939                 err = 0;
940                 if (stat) {
941                         generic_fillattr(inode, stat);
942                         stat->mode = fi->orig_i_mode;
943                         stat->ino = fi->orig_ino;
944                 }
945         }
946 
947         if (refreshed != NULL)
948                 *refreshed = r;
949 
950         return err;
951 }
952 
953 int fuse_reverse_inval_entry(struct super_block *sb, u64 parent_nodeid,
954                              u64 child_nodeid, struct qstr *name)
955 {
956         int err = -ENOTDIR;
957         struct inode *parent;
958         struct dentry *dir;
959         struct dentry *entry;
960 
961         parent = ilookup5(sb, parent_nodeid, fuse_inode_eq, &parent_nodeid);
962         if (!parent)
963                 return -ENOENT;
964 
965         inode_lock(parent);
966         if (!S_ISDIR(parent->i_mode))
967                 goto unlock;
968 
969         err = -ENOENT;
970         dir = d_find_alias(parent);
971         if (!dir)
972                 goto unlock;
973 
974         name->hash = full_name_hash(dir, name->name, name->len);
975         entry = d_lookup(dir, name);
976         dput(dir);
977         if (!entry)
978                 goto unlock;
979 
980         fuse_invalidate_attr(parent);
981         fuse_invalidate_entry(entry);
982 
983         if (child_nodeid != 0 && d_really_is_positive(entry)) {
984                 inode_lock(d_inode(entry));
985                 if (get_node_id(d_inode(entry)) != child_nodeid) {
986                         err = -ENOENT;
987                         goto badentry;
988                 }
989                 if (d_mountpoint(entry)) {
990                         err = -EBUSY;
991                         goto badentry;
992                 }
993                 if (d_is_dir(entry)) {
994                         shrink_dcache_parent(entry);
995                         if (!simple_empty(entry)) {
996                                 err = -ENOTEMPTY;
997                                 goto badentry;
998                         }
999                         d_inode(entry)->i_flags |= S_DEAD;
1000                 }
1001                 dont_mount(entry);
1002                 clear_nlink(d_inode(entry));
1003                 err = 0;
1004  badentry:
1005                 inode_unlock(d_inode(entry));
1006                 if (!err)
1007                         d_delete(entry);
1008         } else {
1009                 err = 0;
1010         }
1011         dput(entry);
1012 
1013  unlock:
1014         inode_unlock(parent);
1015         iput(parent);
1016         return err;
1017 }
1018 
1019 /*
1020  * Calling into a user-controlled filesystem gives the filesystem
1021  * daemon ptrace-like capabilities over the current process.  This
1022  * means, that the filesystem daemon is able to record the exact
1023  * filesystem operations performed, and can also control the behavior
1024  * of the requester process in otherwise impossible ways.  For example
1025  * it can delay the operation for arbitrary length of time allowing
1026  * DoS against the requester.
1027  *
1028  * For this reason only those processes can call into the filesystem,
1029  * for which the owner of the mount has ptrace privilege.  This
1030  * excludes processes started by other users, suid or sgid processes.
1031  */
1032 int fuse_allow_current_process(struct fuse_conn *fc)
1033 {
1034         const struct cred *cred;
1035 
1036         if (fc->allow_other)
1037                 return 1;
1038 
1039         cred = current_cred();
1040         if (uid_eq(cred->euid, fc->user_id) &&
1041             uid_eq(cred->suid, fc->user_id) &&
1042             uid_eq(cred->uid,  fc->user_id) &&
1043             gid_eq(cred->egid, fc->group_id) &&
1044             gid_eq(cred->sgid, fc->group_id) &&
1045             gid_eq(cred->gid,  fc->group_id))
1046                 return 1;
1047 
1048         return 0;
1049 }
1050 
1051 static int fuse_access(struct inode *inode, int mask)
1052 {
1053         struct fuse_conn *fc = get_fuse_conn(inode);
1054         FUSE_ARGS(args);
1055         struct fuse_access_in inarg;
1056         int err;
1057 
1058         BUG_ON(mask & MAY_NOT_BLOCK);
1059 
1060         if (fc->no_access)
1061                 return 0;
1062 
1063         memset(&inarg, 0, sizeof(inarg));
1064         inarg.mask = mask & (MAY_READ | MAY_WRITE | MAY_EXEC);
1065         args.in.h.opcode = FUSE_ACCESS;
1066         args.in.h.nodeid = get_node_id(inode);
1067         args.in.numargs = 1;
1068         args.in.args[0].size = sizeof(inarg);
1069         args.in.args[0].value = &inarg;
1070         err = fuse_simple_request(fc, &args);
1071         if (err == -ENOSYS) {
1072                 fc->no_access = 1;
1073                 err = 0;
1074         }
1075         return err;
1076 }
1077 
1078 static int fuse_perm_getattr(struct inode *inode, int mask)
1079 {
1080         if (mask & MAY_NOT_BLOCK)
1081                 return -ECHILD;
1082 
1083         forget_all_cached_acls(inode);
1084         return fuse_do_getattr(inode, NULL, NULL);
1085 }
1086 
1087 /*
1088  * Check permission.  The two basic access models of FUSE are:
1089  *
1090  * 1) Local access checking ('default_permissions' mount option) based
1091  * on file mode.  This is the plain old disk filesystem permission
1092  * modell.
1093  *
1094  * 2) "Remote" access checking, where server is responsible for
1095  * checking permission in each inode operation.  An exception to this
1096  * is if ->permission() was invoked from sys_access() in which case an
1097  * access request is sent.  Execute permission is still checked
1098  * locally based on file mode.
1099  */
1100 static int fuse_permission(struct inode *inode, int mask)
1101 {
1102         struct fuse_conn *fc = get_fuse_conn(inode);
1103         bool refreshed = false;
1104         int err = 0;
1105 
1106         if (!fuse_allow_current_process(fc))
1107                 return -EACCES;
1108 
1109         /*
1110          * If attributes are needed, refresh them before proceeding
1111          */
1112         if (fc->default_permissions ||
1113             ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))) {
1114                 struct fuse_inode *fi = get_fuse_inode(inode);
1115 
1116                 if (time_before64(fi->i_time, get_jiffies_64())) {
1117                         refreshed = true;
1118 
1119                         err = fuse_perm_getattr(inode, mask);
1120                         if (err)
1121                                 return err;
1122                 }
1123         }
1124 
1125         if (fc->default_permissions) {
1126                 err = generic_permission(inode, mask);
1127 
1128                 /* If permission is denied, try to refresh file
1129                    attributes.  This is also needed, because the root
1130                    node will at first have no permissions */
1131                 if (err == -EACCES && !refreshed) {
1132                         err = fuse_perm_getattr(inode, mask);
1133                         if (!err)
1134                                 err = generic_permission(inode, mask);
1135                 }
1136 
1137                 /* Note: the opposite of the above test does not
1138                    exist.  So if permissions are revoked this won't be
1139                    noticed immediately, only after the attribute
1140                    timeout has expired */
1141         } else if (mask & (MAY_ACCESS | MAY_CHDIR)) {
1142                 err = fuse_access(inode, mask);
1143         } else if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) {
1144                 if (!(inode->i_mode & S_IXUGO)) {
1145                         if (refreshed)
1146                                 return -EACCES;
1147 
1148                         err = fuse_perm_getattr(inode, mask);
1149                         if (!err && !(inode->i_mode & S_IXUGO))
1150                                 return -EACCES;
1151                 }
1152         }
1153         return err;
1154 }
1155 
1156 static int parse_dirfile(char *buf, size_t nbytes, struct file *file,
1157                          struct dir_context *ctx)
1158 {
1159         while (nbytes >= FUSE_NAME_OFFSET) {
1160                 struct fuse_dirent *dirent = (struct fuse_dirent *) buf;
1161                 size_t reclen = FUSE_DIRENT_SIZE(dirent);
1162                 if (!dirent->namelen || dirent->namelen > FUSE_NAME_MAX)
1163                         return -EIO;
1164                 if (reclen > nbytes)
1165                         break;
1166                 if (memchr(dirent->name, '/', dirent->namelen) != NULL)
1167                         return -EIO;
1168 
1169                 if (!dir_emit(ctx, dirent->name, dirent->namelen,
1170                                dirent->ino, dirent->type))
1171                         break;
1172 
1173                 buf += reclen;
1174                 nbytes -= reclen;
1175                 ctx->pos = dirent->off;
1176         }
1177 
1178         return 0;
1179 }
1180 
1181 static int fuse_direntplus_link(struct file *file,
1182                                 struct fuse_direntplus *direntplus,
1183                                 u64 attr_version)
1184 {
1185         struct fuse_entry_out *o = &direntplus->entry_out;
1186         struct fuse_dirent *dirent = &direntplus->dirent;
1187         struct dentry *parent = file->f_path.dentry;
1188         struct qstr name = QSTR_INIT(dirent->name, dirent->namelen);
1189         struct dentry *dentry;
1190         struct dentry *alias;
1191         struct inode *dir = d_inode(parent);
1192         struct fuse_conn *fc;
1193         struct inode *inode;
1194         DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
1195 
1196         if (!o->nodeid) {
1197                 /*
1198                  * Unlike in the case of fuse_lookup, zero nodeid does not mean
1199                  * ENOENT. Instead, it only means the userspace filesystem did
1200                  * not want to return attributes/handle for this entry.
1201                  *
1202                  * So do nothing.
1203                  */
1204                 return 0;
1205         }
1206 
1207         if (name.name[0] == '.') {
1208                 /*
1209                  * We could potentially refresh the attributes of the directory
1210                  * and its parent?
1211                  */
1212                 if (name.len == 1)
1213                         return 0;
1214                 if (name.name[1] == '.' && name.len == 2)
1215                         return 0;
1216         }
1217 
1218         if (invalid_nodeid(o->nodeid))
1219                 return -EIO;
1220         if (!fuse_valid_type(o->attr.mode))
1221                 return -EIO;
1222 
1223         fc = get_fuse_conn(dir);
1224 
1225         name.hash = full_name_hash(parent, name.name, name.len);
1226         dentry = d_lookup(parent, &name);
1227         if (!dentry) {
1228 retry:
1229                 dentry = d_alloc_parallel(parent, &name, &wq);
1230                 if (IS_ERR(dentry))
1231                         return PTR_ERR(dentry);
1232         }
1233         if (!d_in_lookup(dentry)) {
1234                 struct fuse_inode *fi;
1235                 inode = d_inode(dentry);
1236                 if (!inode ||
1237                     get_node_id(inode) != o->nodeid ||
1238                     ((o->attr.mode ^ inode->i_mode) & S_IFMT)) {
1239                         d_invalidate(dentry);
1240                         dput(dentry);
1241                         goto retry;
1242                 }
1243                 if (is_bad_inode(inode)) {
1244                         dput(dentry);
1245                         return -EIO;
1246                 }
1247 
1248                 fi = get_fuse_inode(inode);
1249                 spin_lock(&fc->lock);
1250                 fi->nlookup++;
1251                 spin_unlock(&fc->lock);
1252 
1253                 forget_all_cached_acls(inode);
1254                 fuse_change_attributes(inode, &o->attr,
1255                                        entry_attr_timeout(o),
1256                                        attr_version);
1257                 /*
1258                  * The other branch comes via fuse_iget()
1259                  * which bumps nlookup inside
1260                  */
1261         } else {
1262                 inode = fuse_iget(dir->i_sb, o->nodeid, o->generation,
1263                                   &o->attr, entry_attr_timeout(o),
1264                                   attr_version);
1265                 if (!inode)
1266                         inode = ERR_PTR(-ENOMEM);
1267 
1268                 alias = d_splice_alias(inode, dentry);
1269                 d_lookup_done(dentry);
1270                 if (alias) {
1271                         dput(dentry);
1272                         dentry = alias;
1273                 }
1274                 if (IS_ERR(dentry))
1275                         return PTR_ERR(dentry);
1276         }
1277         if (fc->readdirplus_auto)
1278                 set_bit(FUSE_I_INIT_RDPLUS, &get_fuse_inode(inode)->state);
1279         fuse_change_entry_timeout(dentry, o);
1280 
1281         dput(dentry);
1282         return 0;
1283 }
1284 
1285 static int parse_dirplusfile(char *buf, size_t nbytes, struct file *file,
1286                              struct dir_context *ctx, u64 attr_version)
1287 {
1288         struct fuse_direntplus *direntplus;
1289         struct fuse_dirent *dirent;
1290         size_t reclen;
1291         int over = 0;
1292         int ret;
1293 
1294         while (nbytes >= FUSE_NAME_OFFSET_DIRENTPLUS) {
1295                 direntplus = (struct fuse_direntplus *) buf;
1296                 dirent = &direntplus->dirent;
1297                 reclen = FUSE_DIRENTPLUS_SIZE(direntplus);
1298 
1299                 if (!dirent->namelen || dirent->namelen > FUSE_NAME_MAX)
1300                         return -EIO;
1301                 if (reclen > nbytes)
1302                         break;
1303                 if (memchr(dirent->name, '/', dirent->namelen) != NULL)
1304                         return -EIO;
1305 
1306                 if (!over) {
1307                         /* We fill entries into dstbuf only as much as
1308                            it can hold. But we still continue iterating
1309                            over remaining entries to link them. If not,
1310                            we need to send a FORGET for each of those
1311                            which we did not link.
1312                         */
1313                         over = !dir_emit(ctx, dirent->name, dirent->namelen,
1314                                        dirent->ino, dirent->type);
1315                         if (!over)
1316                                 ctx->pos = dirent->off;
1317                 }
1318 
1319                 buf += reclen;
1320                 nbytes -= reclen;
1321 
1322                 ret = fuse_direntplus_link(file, direntplus, attr_version);
1323                 if (ret)
1324                         fuse_force_forget(file, direntplus->entry_out.nodeid);
1325         }
1326 
1327         return 0;
1328 }
1329 
1330 static int fuse_readdir(struct file *file, struct dir_context *ctx)
1331 {
1332         int plus, err;
1333         size_t nbytes;
1334         struct page *page;
1335         struct inode *inode = file_inode(file);
1336         struct fuse_conn *fc = get_fuse_conn(inode);
1337         struct fuse_req *req;
1338         u64 attr_version = 0;
1339 
1340         if (is_bad_inode(inode))
1341                 return -EIO;
1342 
1343         req = fuse_get_req(fc, 1);
1344         if (IS_ERR(req))
1345                 return PTR_ERR(req);
1346 
1347         page = alloc_page(GFP_KERNEL);
1348         if (!page) {
1349                 fuse_put_request(fc, req);
1350                 return -ENOMEM;
1351         }
1352 
1353         plus = fuse_use_readdirplus(inode, ctx);
1354         req->out.argpages = 1;
1355         req->num_pages = 1;
1356         req->pages[0] = page;
1357         req->page_descs[0].length = PAGE_SIZE;
1358         if (plus) {
1359                 attr_version = fuse_get_attr_version(fc);
1360                 fuse_read_fill(req, file, ctx->pos, PAGE_SIZE,
1361                                FUSE_READDIRPLUS);
1362         } else {
1363                 fuse_read_fill(req, file, ctx->pos, PAGE_SIZE,
1364                                FUSE_READDIR);
1365         }
1366         fuse_lock_inode(inode);
1367         fuse_request_send(fc, req);
1368         fuse_unlock_inode(inode);
1369         nbytes = req->out.args[0].size;
1370         err = req->out.h.error;
1371         fuse_put_request(fc, req);
1372         if (!err) {
1373                 if (plus) {
1374                         err = parse_dirplusfile(page_address(page), nbytes,
1375                                                 file, ctx,
1376                                                 attr_version);
1377                 } else {
1378                         err = parse_dirfile(page_address(page), nbytes, file,
1379                                             ctx);
1380                 }
1381         }
1382 
1383         __free_page(page);
1384         fuse_invalidate_atime(inode);
1385         return err;
1386 }
1387 
1388 static const char *fuse_get_link(struct dentry *dentry,
1389                                  struct inode *inode,
1390                                  struct delayed_call *done)
1391 {
1392         struct fuse_conn *fc = get_fuse_conn(inode);
1393         FUSE_ARGS(args);
1394         char *link;
1395         ssize_t ret;
1396 
1397         if (!dentry)
1398                 return ERR_PTR(-ECHILD);
1399 
1400         link = kmalloc(PAGE_SIZE, GFP_KERNEL);
1401         if (!link)
1402                 return ERR_PTR(-ENOMEM);
1403 
1404         args.in.h.opcode = FUSE_READLINK;
1405         args.in.h.nodeid = get_node_id(inode);
1406         args.out.argvar = 1;
1407         args.out.numargs = 1;
1408         args.out.args[0].size = PAGE_SIZE - 1;
1409         args.out.args[0].value = link;
1410         ret = fuse_simple_request(fc, &args);
1411         if (ret < 0) {
1412                 kfree(link);
1413                 link = ERR_PTR(ret);
1414         } else {
1415                 link[ret] = '\0';
1416                 set_delayed_call(done, kfree_link, link);
1417         }
1418         fuse_invalidate_atime(inode);
1419         return link;
1420 }
1421 
1422 static int fuse_dir_open(struct inode *inode, struct file *file)
1423 {
1424         return fuse_open_common(inode, file, true);
1425 }
1426 
1427 static int fuse_dir_release(struct inode *inode, struct file *file)
1428 {
1429         fuse_release_common(file, FUSE_RELEASEDIR);
1430 
1431         return 0;
1432 }
1433 
1434 static int fuse_dir_fsync(struct file *file, loff_t start, loff_t end,
1435                           int datasync)
1436 {
1437         return fuse_fsync_common(file, start, end, datasync, 1);
1438 }
1439 
1440 static long fuse_dir_ioctl(struct file *file, unsigned int cmd,
1441                             unsigned long arg)
1442 {
1443         struct fuse_conn *fc = get_fuse_conn(file->f_mapping->host);
1444 
1445         /* FUSE_IOCTL_DIR only supported for API version >= 7.18 */
1446         if (fc->minor < 18)
1447                 return -ENOTTY;
1448 
1449         return fuse_ioctl_common(file, cmd, arg, FUSE_IOCTL_DIR);
1450 }
1451 
1452 static long fuse_dir_compat_ioctl(struct file *file, unsigned int cmd,
1453                                    unsigned long arg)
1454 {
1455         struct fuse_conn *fc = get_fuse_conn(file->f_mapping->host);
1456 
1457         if (fc->minor < 18)
1458                 return -ENOTTY;
1459 
1460         return fuse_ioctl_common(file, cmd, arg,
1461                                  FUSE_IOCTL_COMPAT | FUSE_IOCTL_DIR);
1462 }
1463 
1464 static bool update_mtime(unsigned ivalid, bool trust_local_mtime)
1465 {
1466         /* Always update if mtime is explicitly set  */
1467         if (ivalid & ATTR_MTIME_SET)
1468                 return true;
1469 
1470         /* Or if kernel i_mtime is the official one */
1471         if (trust_local_mtime)
1472                 return true;
1473 
1474         /* If it's an open(O_TRUNC) or an ftruncate(), don't update */
1475         if ((ivalid & ATTR_SIZE) && (ivalid & (ATTR_OPEN | ATTR_FILE)))
1476                 return false;
1477 
1478         /* In all other cases update */
1479         return true;
1480 }
1481 
1482 static void iattr_to_fattr(struct iattr *iattr, struct fuse_setattr_in *arg,
1483                            bool trust_local_cmtime)
1484 {
1485         unsigned ivalid = iattr->ia_valid;
1486 
1487         if (ivalid & ATTR_MODE)
1488                 arg->valid |= FATTR_MODE,   arg->mode = iattr->ia_mode;
1489         if (ivalid & ATTR_UID)
1490                 arg->valid |= FATTR_UID,    arg->uid = from_kuid(&init_user_ns, iattr->ia_uid);
1491         if (ivalid & ATTR_GID)
1492                 arg->valid |= FATTR_GID,    arg->gid = from_kgid(&init_user_ns, iattr->ia_gid);
1493         if (ivalid & ATTR_SIZE)
1494                 arg->valid |= FATTR_SIZE,   arg->size = iattr->ia_size;
1495         if (ivalid & ATTR_ATIME) {
1496                 arg->valid |= FATTR_ATIME;
1497                 arg->atime = iattr->ia_atime.tv_sec;
1498                 arg->atimensec = iattr->ia_atime.tv_nsec;
1499                 if (!(ivalid & ATTR_ATIME_SET))
1500                         arg->valid |= FATTR_ATIME_NOW;
1501         }
1502         if ((ivalid & ATTR_MTIME) && update_mtime(ivalid, trust_local_cmtime)) {
1503                 arg->valid |= FATTR_MTIME;
1504                 arg->mtime = iattr->ia_mtime.tv_sec;
1505                 arg->mtimensec = iattr->ia_mtime.tv_nsec;
1506                 if (!(ivalid & ATTR_MTIME_SET) && !trust_local_cmtime)
1507                         arg->valid |= FATTR_MTIME_NOW;
1508         }
1509         if ((ivalid & ATTR_CTIME) && trust_local_cmtime) {
1510                 arg->valid |= FATTR_CTIME;
1511                 arg->ctime = iattr->ia_ctime.tv_sec;
1512                 arg->ctimensec = iattr->ia_ctime.tv_nsec;
1513         }
1514 }
1515 
1516 /*
1517  * Prevent concurrent writepages on inode
1518  *
1519  * This is done by adding a negative bias to the inode write counter
1520  * and waiting for all pending writes to finish.
1521  */
1522 void fuse_set_nowrite(struct inode *inode)
1523 {
1524         struct fuse_conn *fc = get_fuse_conn(inode);
1525         struct fuse_inode *fi = get_fuse_inode(inode);
1526 
1527         BUG_ON(!inode_is_locked(inode));
1528 
1529         spin_lock(&fc->lock);
1530         BUG_ON(fi->writectr < 0);
1531         fi->writectr += FUSE_NOWRITE;
1532         spin_unlock(&fc->lock);
1533         wait_event(fi->page_waitq, fi->writectr == FUSE_NOWRITE);
1534 }
1535 
1536 /*
1537  * Allow writepages on inode
1538  *
1539  * Remove the bias from the writecounter and send any queued
1540  * writepages.
1541  */
1542 static void __fuse_release_nowrite(struct inode *inode)
1543 {
1544         struct fuse_inode *fi = get_fuse_inode(inode);
1545 
1546         BUG_ON(fi->writectr != FUSE_NOWRITE);
1547         fi->writectr = 0;
1548         fuse_flush_writepages(inode);
1549 }
1550 
1551 void fuse_release_nowrite(struct inode *inode)
1552 {
1553         struct fuse_conn *fc = get_fuse_conn(inode);
1554 
1555         spin_lock(&fc->lock);
1556         __fuse_release_nowrite(inode);
1557         spin_unlock(&fc->lock);
1558 }
1559 
1560 static void fuse_setattr_fill(struct fuse_conn *fc, struct fuse_args *args,
1561                               struct inode *inode,
1562                               struct fuse_setattr_in *inarg_p,
1563                               struct fuse_attr_out *outarg_p)
1564 {
1565         args->in.h.opcode = FUSE_SETATTR;
1566         args->in.h.nodeid = get_node_id(inode);
1567         args->in.numargs = 1;
1568         args->in.args[0].size = sizeof(*inarg_p);
1569         args->in.args[0].value = inarg_p;
1570         args->out.numargs = 1;
1571         args->out.args[0].size = sizeof(*outarg_p);
1572         args->out.args[0].value = outarg_p;
1573 }
1574 
1575 /*
1576  * Flush inode->i_mtime to the server
1577  */
1578 int fuse_flush_times(struct inode *inode, struct fuse_file *ff)
1579 {
1580         struct fuse_conn *fc = get_fuse_conn(inode);
1581         FUSE_ARGS(args);
1582         struct fuse_setattr_in inarg;
1583         struct fuse_attr_out outarg;
1584 
1585         memset(&inarg, 0, sizeof(inarg));
1586         memset(&outarg, 0, sizeof(outarg));
1587 
1588         inarg.valid = FATTR_MTIME;
1589         inarg.mtime = inode->i_mtime.tv_sec;
1590         inarg.mtimensec = inode->i_mtime.tv_nsec;
1591         if (fc->minor >= 23) {
1592                 inarg.valid |= FATTR_CTIME;
1593                 inarg.ctime = inode->i_ctime.tv_sec;
1594                 inarg.ctimensec = inode->i_ctime.tv_nsec;
1595         }
1596         if (ff) {
1597                 inarg.valid |= FATTR_FH;
1598                 inarg.fh = ff->fh;
1599         }
1600         fuse_setattr_fill(fc, &args, inode, &inarg, &outarg);
1601 
1602         return fuse_simple_request(fc, &args);
1603 }
1604 
1605 /*
1606  * Set attributes, and at the same time refresh them.
1607  *
1608  * Truncation is slightly complicated, because the 'truncate' request
1609  * may fail, in which case we don't want to touch the mapping.
1610  * vmtruncate() doesn't allow for this case, so do the rlimit checking
1611  * and the actual truncation by hand.
1612  */
1613 int fuse_do_setattr(struct dentry *dentry, struct iattr *attr,
1614                     struct file *file)
1615 {
1616         struct inode *inode = d_inode(dentry);
1617         struct fuse_conn *fc = get_fuse_conn(inode);
1618         struct fuse_inode *fi = get_fuse_inode(inode);
1619         FUSE_ARGS(args);
1620         struct fuse_setattr_in inarg;
1621         struct fuse_attr_out outarg;
1622         bool is_truncate = false;
1623         bool is_wb = fc->writeback_cache;
1624         loff_t oldsize;
1625         int err;
1626         bool trust_local_cmtime = is_wb && S_ISREG(inode->i_mode);
1627 
1628         if (!fc->default_permissions)
1629                 attr->ia_valid |= ATTR_FORCE;
1630 
1631         err = setattr_prepare(dentry, attr);
1632         if (err)
1633                 return err;
1634 
1635         if (attr->ia_valid & ATTR_OPEN) {
1636                 if (fc->atomic_o_trunc)
1637                         return 0;
1638                 file = NULL;
1639         }
1640 
1641         if (attr->ia_valid & ATTR_SIZE)
1642                 is_truncate = true;
1643 
1644         if (is_truncate) {
1645                 fuse_set_nowrite(inode);
1646                 set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
1647                 if (trust_local_cmtime && attr->ia_size != inode->i_size)
1648                         attr->ia_valid |= ATTR_MTIME | ATTR_CTIME;
1649         }
1650 
1651         memset(&inarg, 0, sizeof(inarg));
1652         memset(&outarg, 0, sizeof(outarg));
1653         iattr_to_fattr(attr, &inarg, trust_local_cmtime);
1654         if (file) {
1655                 struct fuse_file *ff = file->private_data;
1656                 inarg.valid |= FATTR_FH;
1657                 inarg.fh = ff->fh;
1658         }
1659         if (attr->ia_valid & ATTR_SIZE) {
1660                 /* For mandatory locking in truncate */
1661                 inarg.valid |= FATTR_LOCKOWNER;
1662                 inarg.lock_owner = fuse_lock_owner_id(fc, current->files);
1663         }
1664         fuse_setattr_fill(fc, &args, inode, &inarg, &outarg);
1665         err = fuse_simple_request(fc, &args);
1666         if (err) {
1667                 if (err == -EINTR)
1668                         fuse_invalidate_attr(inode);
1669                 goto error;
1670         }
1671 
1672         if ((inode->i_mode ^ outarg.attr.mode) & S_IFMT) {
1673                 make_bad_inode(inode);
1674                 err = -EIO;
1675                 goto error;
1676         }
1677 
1678         spin_lock(&fc->lock);
1679         /* the kernel maintains i_mtime locally */
1680         if (trust_local_cmtime) {
1681                 if (attr->ia_valid & ATTR_MTIME)
1682                         inode->i_mtime = attr->ia_mtime;
1683                 if (attr->ia_valid & ATTR_CTIME)
1684                         inode->i_ctime = attr->ia_ctime;
1685                 /* FIXME: clear I_DIRTY_SYNC? */
1686         }
1687 
1688         fuse_change_attributes_common(inode, &outarg.attr,
1689                                       attr_timeout(&outarg));
1690         oldsize = inode->i_size;
1691         /* see the comment in fuse_change_attributes() */
1692         if (!is_wb || is_truncate || !S_ISREG(inode->i_mode))
1693                 i_size_write(inode, outarg.attr.size);
1694 
1695         if (is_truncate) {
1696                 /* NOTE: this may release/reacquire fc->lock */
1697                 __fuse_release_nowrite(inode);
1698         }
1699         spin_unlock(&fc->lock);
1700 
1701         /*
1702          * Only call invalidate_inode_pages2() after removing
1703          * FUSE_NOWRITE, otherwise fuse_launder_page() would deadlock.
1704          */
1705         if ((is_truncate || !is_wb) &&
1706             S_ISREG(inode->i_mode) && oldsize != outarg.attr.size) {
1707                 truncate_pagecache(inode, outarg.attr.size);
1708                 invalidate_inode_pages2(inode->i_mapping);
1709         }
1710 
1711         clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
1712         return 0;
1713 
1714 error:
1715         if (is_truncate)
1716                 fuse_release_nowrite(inode);
1717 
1718         clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
1719         return err;
1720 }
1721 
1722 static int fuse_setattr(struct dentry *entry, struct iattr *attr)
1723 {
1724         struct inode *inode = d_inode(entry);
1725         struct fuse_conn *fc = get_fuse_conn(inode);
1726         struct file *file = (attr->ia_valid & ATTR_FILE) ? attr->ia_file : NULL;
1727         int ret;
1728 
1729         if (!fuse_allow_current_process(get_fuse_conn(inode)))
1730                 return -EACCES;
1731 
1732         if (attr->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID)) {
1733                 attr->ia_valid &= ~(ATTR_KILL_SUID | ATTR_KILL_SGID |
1734                                     ATTR_MODE);
1735 
1736                 /*
1737                  * The only sane way to reliably kill suid/sgid is to do it in
1738                  * the userspace filesystem
1739                  *
1740                  * This should be done on write(), truncate() and chown().
1741                  */
1742                 if (!fc->handle_killpriv) {
1743                         /*
1744                          * ia_mode calculation may have used stale i_mode.
1745                          * Refresh and recalculate.
1746                          */
1747                         ret = fuse_do_getattr(inode, NULL, file);
1748                         if (ret)
1749                                 return ret;
1750 
1751                         attr->ia_mode = inode->i_mode;
1752                         if (inode->i_mode & S_ISUID) {
1753                                 attr->ia_valid |= ATTR_MODE;
1754                                 attr->ia_mode &= ~S_ISUID;
1755                         }
1756                         if ((inode->i_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1757                                 attr->ia_valid |= ATTR_MODE;
1758                                 attr->ia_mode &= ~S_ISGID;
1759                         }
1760                 }
1761         }
1762         if (!attr->ia_valid)
1763                 return 0;
1764 
1765         ret = fuse_do_setattr(entry, attr, file);
1766         if (!ret) {
1767                 /*
1768                  * If filesystem supports acls it may have updated acl xattrs in
1769                  * the filesystem, so forget cached acls for the inode.
1770                  */
1771                 if (fc->posix_acl)
1772                         forget_all_cached_acls(inode);
1773 
1774                 /* Directory mode changed, may need to revalidate access */
1775                 if (d_is_dir(entry) && (attr->ia_valid & ATTR_MODE))
1776                         fuse_invalidate_entry_cache(entry);
1777         }
1778         return ret;
1779 }
1780 
1781 static int fuse_getattr(const struct path *path, struct kstat *stat,
1782                         u32 request_mask, unsigned int flags)
1783 {
1784         struct inode *inode = d_inode(path->dentry);
1785         struct fuse_conn *fc = get_fuse_conn(inode);
1786 
1787         if (!fuse_allow_current_process(fc))
1788                 return -EACCES;
1789 
1790         return fuse_update_attributes(inode, stat, NULL, NULL);
1791 }
1792 
1793 static const struct inode_operations fuse_dir_inode_operations = {
1794         .lookup         = fuse_lookup,
1795         .mkdir          = fuse_mkdir,
1796         .symlink        = fuse_symlink,
1797         .unlink         = fuse_unlink,
1798         .rmdir          = fuse_rmdir,
1799         .rename         = fuse_rename2,
1800         .link           = fuse_link,
1801         .setattr        = fuse_setattr,
1802         .create         = fuse_create,
1803         .atomic_open    = fuse_atomic_open,
1804         .mknod          = fuse_mknod,
1805         .permission     = fuse_permission,
1806         .getattr        = fuse_getattr,
1807         .listxattr      = fuse_listxattr,
1808         .get_acl        = fuse_get_acl,
1809         .set_acl        = fuse_set_acl,
1810 };
1811 
1812 static const struct file_operations fuse_dir_operations = {
1813         .llseek         = generic_file_llseek,
1814         .read           = generic_read_dir,
1815         .iterate_shared = fuse_readdir,
1816         .open           = fuse_dir_open,
1817         .release        = fuse_dir_release,
1818         .fsync          = fuse_dir_fsync,
1819         .unlocked_ioctl = fuse_dir_ioctl,
1820         .compat_ioctl   = fuse_dir_compat_ioctl,
1821 };
1822 
1823 static const struct inode_operations fuse_common_inode_operations = {
1824         .setattr        = fuse_setattr,
1825         .permission     = fuse_permission,
1826         .getattr        = fuse_getattr,
1827         .listxattr      = fuse_listxattr,
1828         .get_acl        = fuse_get_acl,
1829         .set_acl        = fuse_set_acl,
1830 };
1831 
1832 static const struct inode_operations fuse_symlink_inode_operations = {
1833         .setattr        = fuse_setattr,
1834         .get_link       = fuse_get_link,
1835         .getattr        = fuse_getattr,
1836         .listxattr      = fuse_listxattr,
1837 };
1838 
1839 void fuse_init_common(struct inode *inode)
1840 {
1841         inode->i_op = &fuse_common_inode_operations;
1842 }
1843 
1844 void fuse_init_dir(struct inode *inode)
1845 {
1846         inode->i_op = &fuse_dir_inode_operations;
1847         inode->i_fop = &fuse_dir_operations;
1848 }
1849 
1850 void fuse_init_symlink(struct inode *inode)
1851 {
1852         inode->i_op = &fuse_symlink_inode_operations;
1853 }
1854 

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