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TOMOYO Linux Cross Reference
Linux/fs/autofs4/root.c

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  1 /*
  2  * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
  3  * Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
  4  * Copyright 2001-2006 Ian Kent <raven@themaw.net>
  5  *
  6  * This file is part of the Linux kernel and is made available under
  7  * the terms of the GNU General Public License, version 2, or at your
  8  * option, any later version, incorporated herein by reference.
  9  */
 10 
 11 #include <linux/capability.h>
 12 #include <linux/errno.h>
 13 #include <linux/stat.h>
 14 #include <linux/slab.h>
 15 #include <linux/param.h>
 16 #include <linux/time.h>
 17 #include <linux/compat.h>
 18 #include <linux/mutex.h>
 19 
 20 #include "autofs_i.h"
 21 
 22 static int autofs4_dir_symlink(struct inode *, struct dentry *, const char *);
 23 static int autofs4_dir_unlink(struct inode *, struct dentry *);
 24 static int autofs4_dir_rmdir(struct inode *, struct dentry *);
 25 static int autofs4_dir_mkdir(struct inode *, struct dentry *, umode_t);
 26 static long autofs4_root_ioctl(struct file *, unsigned int, unsigned long);
 27 #ifdef CONFIG_COMPAT
 28 static long autofs4_root_compat_ioctl(struct file *,
 29                                       unsigned int, unsigned long);
 30 #endif
 31 static int autofs4_dir_open(struct inode *inode, struct file *file);
 32 static struct dentry *autofs4_lookup(struct inode *,
 33                                      struct dentry *, unsigned int);
 34 static struct vfsmount *autofs4_d_automount(struct path *);
 35 static int autofs4_d_manage(struct dentry *, bool);
 36 static void autofs4_dentry_release(struct dentry *);
 37 
 38 const struct file_operations autofs4_root_operations = {
 39         .open           = dcache_dir_open,
 40         .release        = dcache_dir_close,
 41         .read           = generic_read_dir,
 42         .iterate        = dcache_readdir,
 43         .llseek         = dcache_dir_lseek,
 44         .unlocked_ioctl = autofs4_root_ioctl,
 45 #ifdef CONFIG_COMPAT
 46         .compat_ioctl   = autofs4_root_compat_ioctl,
 47 #endif
 48 };
 49 
 50 const struct file_operations autofs4_dir_operations = {
 51         .open           = autofs4_dir_open,
 52         .release        = dcache_dir_close,
 53         .read           = generic_read_dir,
 54         .iterate        = dcache_readdir,
 55         .llseek         = dcache_dir_lseek,
 56 };
 57 
 58 const struct inode_operations autofs4_dir_inode_operations = {
 59         .lookup         = autofs4_lookup,
 60         .unlink         = autofs4_dir_unlink,
 61         .symlink        = autofs4_dir_symlink,
 62         .mkdir          = autofs4_dir_mkdir,
 63         .rmdir          = autofs4_dir_rmdir,
 64 };
 65 
 66 const struct dentry_operations autofs4_dentry_operations = {
 67         .d_automount    = autofs4_d_automount,
 68         .d_manage       = autofs4_d_manage,
 69         .d_release      = autofs4_dentry_release,
 70 };
 71 
 72 static void autofs4_add_active(struct dentry *dentry)
 73 {
 74         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 75         struct autofs_info *ino;
 76 
 77         ino = autofs4_dentry_ino(dentry);
 78         if (ino) {
 79                 spin_lock(&sbi->lookup_lock);
 80                 if (!ino->active_count) {
 81                         if (list_empty(&ino->active))
 82                                 list_add(&ino->active, &sbi->active_list);
 83                 }
 84                 ino->active_count++;
 85                 spin_unlock(&sbi->lookup_lock);
 86         }
 87 }
 88 
 89 static void autofs4_del_active(struct dentry *dentry)
 90 {
 91         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 92         struct autofs_info *ino;
 93 
 94         ino = autofs4_dentry_ino(dentry);
 95         if (ino) {
 96                 spin_lock(&sbi->lookup_lock);
 97                 ino->active_count--;
 98                 if (!ino->active_count) {
 99                         if (!list_empty(&ino->active))
100                                 list_del_init(&ino->active);
101                 }
102                 spin_unlock(&sbi->lookup_lock);
103         }
104 }
105 
106 static int autofs4_dir_open(struct inode *inode, struct file *file)
107 {
108         struct dentry *dentry = file->f_path.dentry;
109         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
110 
111         pr_debug("file=%p dentry=%p %pd\n", file, dentry, dentry);
112 
113         if (autofs4_oz_mode(sbi))
114                 goto out;
115 
116         /*
117          * An empty directory in an autofs file system is always a
118          * mount point. The daemon must have failed to mount this
119          * during lookup so it doesn't exist. This can happen, for
120          * example, if user space returns an incorrect status for a
121          * mount request. Otherwise we're doing a readdir on the
122          * autofs file system so just let the libfs routines handle
123          * it.
124          */
125         spin_lock(&sbi->lookup_lock);
126         if (!d_mountpoint(dentry) && simple_empty(dentry)) {
127                 spin_unlock(&sbi->lookup_lock);
128                 return -ENOENT;
129         }
130         spin_unlock(&sbi->lookup_lock);
131 
132 out:
133         return dcache_dir_open(inode, file);
134 }
135 
136 static void autofs4_dentry_release(struct dentry *de)
137 {
138         struct autofs_info *ino = autofs4_dentry_ino(de);
139         struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb);
140 
141         pr_debug("releasing %p\n", de);
142 
143         if (!ino)
144                 return;
145 
146         if (sbi) {
147                 spin_lock(&sbi->lookup_lock);
148                 if (!list_empty(&ino->active))
149                         list_del(&ino->active);
150                 if (!list_empty(&ino->expiring))
151                         list_del(&ino->expiring);
152                 spin_unlock(&sbi->lookup_lock);
153         }
154 
155         autofs4_free_ino(ino);
156 }
157 
158 static struct dentry *autofs4_lookup_active(struct dentry *dentry)
159 {
160         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
161         struct dentry *parent = dentry->d_parent;
162         struct qstr *name = &dentry->d_name;
163         unsigned int len = name->len;
164         unsigned int hash = name->hash;
165         const unsigned char *str = name->name;
166         struct list_head *p, *head;
167 
168         head = &sbi->active_list;
169         if (list_empty(head))
170                 return NULL;
171         spin_lock(&sbi->lookup_lock);
172         list_for_each(p, head) {
173                 struct autofs_info *ino;
174                 struct dentry *active;
175                 struct qstr *qstr;
176 
177                 ino = list_entry(p, struct autofs_info, active);
178                 active = ino->dentry;
179 
180                 spin_lock(&active->d_lock);
181 
182                 /* Already gone? */
183                 if ((int) d_count(active) <= 0)
184                         goto next;
185 
186                 qstr = &active->d_name;
187 
188                 if (active->d_name.hash != hash)
189                         goto next;
190                 if (active->d_parent != parent)
191                         goto next;
192 
193                 if (qstr->len != len)
194                         goto next;
195                 if (memcmp(qstr->name, str, len))
196                         goto next;
197 
198                 if (d_unhashed(active)) {
199                         dget_dlock(active);
200                         spin_unlock(&active->d_lock);
201                         spin_unlock(&sbi->lookup_lock);
202                         return active;
203                 }
204 next:
205                 spin_unlock(&active->d_lock);
206         }
207         spin_unlock(&sbi->lookup_lock);
208 
209         return NULL;
210 }
211 
212 static struct dentry *autofs4_lookup_expiring(struct dentry *dentry,
213                                               bool rcu_walk)
214 {
215         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
216         struct dentry *parent = dentry->d_parent;
217         struct qstr *name = &dentry->d_name;
218         unsigned int len = name->len;
219         unsigned int hash = name->hash;
220         const unsigned char *str = name->name;
221         struct list_head *p, *head;
222 
223         head = &sbi->expiring_list;
224         if (list_empty(head))
225                 return NULL;
226         spin_lock(&sbi->lookup_lock);
227         list_for_each(p, head) {
228                 struct autofs_info *ino;
229                 struct dentry *expiring;
230                 struct qstr *qstr;
231 
232                 if (rcu_walk) {
233                         spin_unlock(&sbi->lookup_lock);
234                         return ERR_PTR(-ECHILD);
235                 }
236 
237                 ino = list_entry(p, struct autofs_info, expiring);
238                 expiring = ino->dentry;
239 
240                 spin_lock(&expiring->d_lock);
241 
242                 /* We've already been dentry_iput or unlinked */
243                 if (d_really_is_negative(expiring))
244                         goto next;
245 
246                 qstr = &expiring->d_name;
247 
248                 if (expiring->d_name.hash != hash)
249                         goto next;
250                 if (expiring->d_parent != parent)
251                         goto next;
252 
253                 if (qstr->len != len)
254                         goto next;
255                 if (memcmp(qstr->name, str, len))
256                         goto next;
257 
258                 if (d_unhashed(expiring)) {
259                         dget_dlock(expiring);
260                         spin_unlock(&expiring->d_lock);
261                         spin_unlock(&sbi->lookup_lock);
262                         return expiring;
263                 }
264 next:
265                 spin_unlock(&expiring->d_lock);
266         }
267         spin_unlock(&sbi->lookup_lock);
268 
269         return NULL;
270 }
271 
272 static int autofs4_mount_wait(struct dentry *dentry, bool rcu_walk)
273 {
274         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
275         struct autofs_info *ino = autofs4_dentry_ino(dentry);
276         int status = 0;
277 
278         if (ino->flags & AUTOFS_INF_PENDING) {
279                 if (rcu_walk)
280                         return -ECHILD;
281                 pr_debug("waiting for mount name=%pd\n", dentry);
282                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
283                 pr_debug("mount wait done status=%d\n", status);
284         }
285         ino->last_used = jiffies;
286         return status;
287 }
288 
289 static int do_expire_wait(struct dentry *dentry, bool rcu_walk)
290 {
291         struct dentry *expiring;
292 
293         expiring = autofs4_lookup_expiring(dentry, rcu_walk);
294         if (IS_ERR(expiring))
295                 return PTR_ERR(expiring);
296         if (!expiring)
297                 return autofs4_expire_wait(dentry, rcu_walk);
298         else {
299                 /*
300                  * If we are racing with expire the request might not
301                  * be quite complete, but the directory has been removed
302                  * so it must have been successful, just wait for it.
303                  */
304                 autofs4_expire_wait(expiring, 0);
305                 autofs4_del_expiring(expiring);
306                 dput(expiring);
307         }
308         return 0;
309 }
310 
311 static struct dentry *autofs4_mountpoint_changed(struct path *path)
312 {
313         struct dentry *dentry = path->dentry;
314         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
315 
316         /*
317          * If this is an indirect mount the dentry could have gone away
318          * as a result of an expire and a new one created.
319          */
320         if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) {
321                 struct dentry *parent = dentry->d_parent;
322                 struct autofs_info *ino;
323                 struct dentry *new;
324 
325                 new = d_lookup(parent, &dentry->d_name);
326                 if (!new)
327                         return NULL;
328                 ino = autofs4_dentry_ino(new);
329                 ino->last_used = jiffies;
330                 dput(path->dentry);
331                 path->dentry = new;
332         }
333         return path->dentry;
334 }
335 
336 static struct vfsmount *autofs4_d_automount(struct path *path)
337 {
338         struct dentry *dentry = path->dentry;
339         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
340         struct autofs_info *ino = autofs4_dentry_ino(dentry);
341         int status;
342 
343         pr_debug("dentry=%p %pd\n", dentry, dentry);
344 
345         /* The daemon never triggers a mount. */
346         if (autofs4_oz_mode(sbi))
347                 return NULL;
348 
349         /*
350          * If an expire request is pending everyone must wait.
351          * If the expire fails we're still mounted so continue
352          * the follow and return. A return of -EAGAIN (which only
353          * happens with indirect mounts) means the expire completed
354          * and the directory was removed, so just go ahead and try
355          * the mount.
356          */
357         status = do_expire_wait(dentry, 0);
358         if (status && status != -EAGAIN)
359                 return NULL;
360 
361         /* Callback to the daemon to perform the mount or wait */
362         spin_lock(&sbi->fs_lock);
363         if (ino->flags & AUTOFS_INF_PENDING) {
364                 spin_unlock(&sbi->fs_lock);
365                 status = autofs4_mount_wait(dentry, 0);
366                 if (status)
367                         return ERR_PTR(status);
368                 goto done;
369         }
370 
371         /*
372          * If the dentry is a symlink it's equivalent to a directory
373          * having d_mountpoint() true, so there's no need to call back
374          * to the daemon.
375          */
376         if (d_really_is_positive(dentry) && d_is_symlink(dentry)) {
377                 spin_unlock(&sbi->fs_lock);
378                 goto done;
379         }
380 
381         if (!d_mountpoint(dentry)) {
382                 /*
383                  * It's possible that user space hasn't removed directories
384                  * after umounting a rootless multi-mount, although it
385                  * should. For v5 have_submounts() is sufficient to handle
386                  * this because the leaves of the directory tree under the
387                  * mount never trigger mounts themselves (they have an autofs
388                  * trigger mount mounted on them). But v4 pseudo direct mounts
389                  * do need the leaves to trigger mounts. In this case we
390                  * have no choice but to use the list_empty() check and
391                  * require user space behave.
392                  */
393                 if (sbi->version > 4) {
394                         if (have_submounts(dentry)) {
395                                 spin_unlock(&sbi->fs_lock);
396                                 goto done;
397                         }
398                 } else {
399                         if (!simple_empty(dentry)) {
400                                 spin_unlock(&sbi->fs_lock);
401                                 goto done;
402                         }
403                 }
404                 ino->flags |= AUTOFS_INF_PENDING;
405                 spin_unlock(&sbi->fs_lock);
406                 status = autofs4_mount_wait(dentry, 0);
407                 spin_lock(&sbi->fs_lock);
408                 ino->flags &= ~AUTOFS_INF_PENDING;
409                 if (status) {
410                         spin_unlock(&sbi->fs_lock);
411                         return ERR_PTR(status);
412                 }
413         }
414         spin_unlock(&sbi->fs_lock);
415 done:
416         /* Mount succeeded, check if we ended up with a new dentry */
417         dentry = autofs4_mountpoint_changed(path);
418         if (!dentry)
419                 return ERR_PTR(-ENOENT);
420 
421         return NULL;
422 }
423 
424 static int autofs4_d_manage(struct dentry *dentry, bool rcu_walk)
425 {
426         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
427         struct autofs_info *ino = autofs4_dentry_ino(dentry);
428         int status;
429 
430         pr_debug("dentry=%p %pd\n", dentry, dentry);
431 
432         /* The daemon never waits. */
433         if (autofs4_oz_mode(sbi)) {
434                 if (!d_mountpoint(dentry))
435                         return -EISDIR;
436                 return 0;
437         }
438 
439         /* Wait for pending expires */
440         if (do_expire_wait(dentry, rcu_walk) == -ECHILD)
441                 return -ECHILD;
442 
443         /*
444          * This dentry may be under construction so wait on mount
445          * completion.
446          */
447         status = autofs4_mount_wait(dentry, rcu_walk);
448         if (status)
449                 return status;
450 
451         if (rcu_walk) {
452                 /* We don't need fs_lock in rcu_walk mode,
453                  * just testing 'AUTOFS_INFO_NO_RCU' is enough.
454                  * simple_empty() takes a spinlock, so leave it
455                  * to last.
456                  * We only return -EISDIR when certain this isn't
457                  * a mount-trap.
458                  */
459                 struct inode *inode;
460 
461                 if (ino->flags & (AUTOFS_INF_EXPIRING | AUTOFS_INF_NO_RCU))
462                         return 0;
463                 if (d_mountpoint(dentry))
464                         return 0;
465                 inode = d_inode_rcu(dentry);
466                 if (inode && S_ISLNK(inode->i_mode))
467                         return -EISDIR;
468                 if (list_empty(&dentry->d_subdirs))
469                         return 0;
470                 if (!simple_empty(dentry))
471                         return -EISDIR;
472                 return 0;
473         }
474 
475         spin_lock(&sbi->fs_lock);
476         /*
477          * If the dentry has been selected for expire while we slept
478          * on the lock then it might go away. We'll deal with that in
479          * ->d_automount() and wait on a new mount if the expire
480          * succeeds or return here if it doesn't (since there's no
481          * mount to follow with a rootless multi-mount).
482          */
483         if (!(ino->flags & AUTOFS_INF_EXPIRING)) {
484                 /*
485                  * Any needed mounting has been completed and the path
486                  * updated so check if this is a rootless multi-mount so
487                  * we can avoid needless calls ->d_automount() and avoid
488                  * an incorrect ELOOP error return.
489                  */
490                 if ((!d_mountpoint(dentry) && !simple_empty(dentry)) ||
491                     (d_really_is_positive(dentry) && d_is_symlink(dentry)))
492                         status = -EISDIR;
493         }
494         spin_unlock(&sbi->fs_lock);
495 
496         return status;
497 }
498 
499 /* Lookups in the root directory */
500 static struct dentry *autofs4_lookup(struct inode *dir,
501                                      struct dentry *dentry, unsigned int flags)
502 {
503         struct autofs_sb_info *sbi;
504         struct autofs_info *ino;
505         struct dentry *active;
506 
507         pr_debug("name = %pd\n", dentry);
508 
509         /* File name too long to exist */
510         if (dentry->d_name.len > NAME_MAX)
511                 return ERR_PTR(-ENAMETOOLONG);
512 
513         sbi = autofs4_sbi(dir->i_sb);
514 
515         pr_debug("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d\n",
516                  current->pid, task_pgrp_nr(current), sbi->catatonic,
517                  autofs4_oz_mode(sbi));
518 
519         active = autofs4_lookup_active(dentry);
520         if (active)
521                 return active;
522         else {
523                 /*
524                  * A dentry that is not within the root can never trigger a
525                  * mount operation, unless the directory already exists, so we
526                  * can return fail immediately.  The daemon however does need
527                  * to create directories within the file system.
528                  */
529                 if (!autofs4_oz_mode(sbi) && !IS_ROOT(dentry->d_parent))
530                         return ERR_PTR(-ENOENT);
531 
532                 /* Mark entries in the root as mount triggers */
533                 if (IS_ROOT(dentry->d_parent) &&
534                     autofs_type_indirect(sbi->type))
535                         __managed_dentry_set_managed(dentry);
536 
537                 ino = autofs4_new_ino(sbi);
538                 if (!ino)
539                         return ERR_PTR(-ENOMEM);
540 
541                 dentry->d_fsdata = ino;
542                 ino->dentry = dentry;
543 
544                 autofs4_add_active(dentry);
545         }
546         return NULL;
547 }
548 
549 static int autofs4_dir_symlink(struct inode *dir, 
550                                struct dentry *dentry,
551                                const char *symname)
552 {
553         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
554         struct autofs_info *ino = autofs4_dentry_ino(dentry);
555         struct autofs_info *p_ino;
556         struct inode *inode;
557         size_t size = strlen(symname);
558         char *cp;
559 
560         pr_debug("%s <- %pd\n", symname, dentry);
561 
562         if (!autofs4_oz_mode(sbi))
563                 return -EACCES;
564 
565         BUG_ON(!ino);
566 
567         autofs4_clean_ino(ino);
568 
569         autofs4_del_active(dentry);
570 
571         cp = kmalloc(size + 1, GFP_KERNEL);
572         if (!cp)
573                 return -ENOMEM;
574 
575         strcpy(cp, symname);
576 
577         inode = autofs4_get_inode(dir->i_sb, S_IFLNK | 0555);
578         if (!inode) {
579                 kfree(cp);
580                 if (!dentry->d_fsdata)
581                         kfree(ino);
582                 return -ENOMEM;
583         }
584         inode->i_private = cp;
585         inode->i_size = size;
586         d_add(dentry, inode);
587 
588         dget(dentry);
589         atomic_inc(&ino->count);
590         p_ino = autofs4_dentry_ino(dentry->d_parent);
591         if (p_ino && !IS_ROOT(dentry))
592                 atomic_inc(&p_ino->count);
593 
594         dir->i_mtime = CURRENT_TIME;
595 
596         return 0;
597 }
598 
599 /*
600  * NOTE!
601  *
602  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
603  * that the file no longer exists. However, doing that means that the
604  * VFS layer can turn the dentry into a negative dentry.  We don't want
605  * this, because the unlink is probably the result of an expire.
606  * We simply d_drop it and add it to a expiring list in the super block,
607  * which allows the dentry lookup to check for an incomplete expire.
608  *
609  * If a process is blocked on the dentry waiting for the expire to finish,
610  * it will invalidate the dentry and try to mount with a new one.
611  *
612  * Also see autofs4_dir_rmdir()..
613  */
614 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
615 {
616         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
617         struct autofs_info *ino = autofs4_dentry_ino(dentry);
618         struct autofs_info *p_ino;
619 
620         /* This allows root to remove symlinks */
621         if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
622                 return -EPERM;
623 
624         if (atomic_dec_and_test(&ino->count)) {
625                 p_ino = autofs4_dentry_ino(dentry->d_parent);
626                 if (p_ino && !IS_ROOT(dentry))
627                         atomic_dec(&p_ino->count);
628         }
629         dput(ino->dentry);
630 
631         d_inode(dentry)->i_size = 0;
632         clear_nlink(d_inode(dentry));
633 
634         dir->i_mtime = CURRENT_TIME;
635 
636         spin_lock(&sbi->lookup_lock);
637         __autofs4_add_expiring(dentry);
638         d_drop(dentry);
639         spin_unlock(&sbi->lookup_lock);
640 
641         return 0;
642 }
643 
644 /*
645  * Version 4 of autofs provides a pseudo direct mount implementation
646  * that relies on directories at the leaves of a directory tree under
647  * an indirect mount to trigger mounts. To allow for this we need to
648  * set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves
649  * of the directory tree. There is no need to clear the automount flag
650  * following a mount or restore it after an expire because these mounts
651  * are always covered. However, it is necessary to ensure that these
652  * flags are clear on non-empty directories to avoid unnecessary calls
653  * during path walks.
654  */
655 static void autofs_set_leaf_automount_flags(struct dentry *dentry)
656 {
657         struct dentry *parent;
658 
659         /* root and dentrys in the root are already handled */
660         if (IS_ROOT(dentry->d_parent))
661                 return;
662 
663         managed_dentry_set_managed(dentry);
664 
665         parent = dentry->d_parent;
666         /* only consider parents below dentrys in the root */
667         if (IS_ROOT(parent->d_parent))
668                 return;
669         managed_dentry_clear_managed(parent);
670 }
671 
672 static void autofs_clear_leaf_automount_flags(struct dentry *dentry)
673 {
674         struct list_head *d_child;
675         struct dentry *parent;
676 
677         /* flags for dentrys in the root are handled elsewhere */
678         if (IS_ROOT(dentry->d_parent))
679                 return;
680 
681         managed_dentry_clear_managed(dentry);
682 
683         parent = dentry->d_parent;
684         /* only consider parents below dentrys in the root */
685         if (IS_ROOT(parent->d_parent))
686                 return;
687         d_child = &dentry->d_child;
688         /* Set parent managed if it's becoming empty */
689         if (d_child->next == &parent->d_subdirs &&
690             d_child->prev == &parent->d_subdirs)
691                 managed_dentry_set_managed(parent);
692 }
693 
694 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
695 {
696         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
697         struct autofs_info *ino = autofs4_dentry_ino(dentry);
698         struct autofs_info *p_ino;
699 
700         pr_debug("dentry %p, removing %pd\n", dentry, dentry);
701 
702         if (!autofs4_oz_mode(sbi))
703                 return -EACCES;
704 
705         spin_lock(&sbi->lookup_lock);
706         if (!simple_empty(dentry)) {
707                 spin_unlock(&sbi->lookup_lock);
708                 return -ENOTEMPTY;
709         }
710         __autofs4_add_expiring(dentry);
711         d_drop(dentry);
712         spin_unlock(&sbi->lookup_lock);
713 
714         if (sbi->version < 5)
715                 autofs_clear_leaf_automount_flags(dentry);
716 
717         if (atomic_dec_and_test(&ino->count)) {
718                 p_ino = autofs4_dentry_ino(dentry->d_parent);
719                 if (p_ino && dentry->d_parent != dentry)
720                         atomic_dec(&p_ino->count);
721         }
722         dput(ino->dentry);
723         d_inode(dentry)->i_size = 0;
724         clear_nlink(d_inode(dentry));
725 
726         if (dir->i_nlink)
727                 drop_nlink(dir);
728 
729         return 0;
730 }
731 
732 static int autofs4_dir_mkdir(struct inode *dir,
733                              struct dentry *dentry, umode_t mode)
734 {
735         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
736         struct autofs_info *ino = autofs4_dentry_ino(dentry);
737         struct autofs_info *p_ino;
738         struct inode *inode;
739 
740         if (!autofs4_oz_mode(sbi))
741                 return -EACCES;
742 
743         pr_debug("dentry %p, creating %pd\n", dentry, dentry);
744 
745         BUG_ON(!ino);
746 
747         autofs4_clean_ino(ino);
748 
749         autofs4_del_active(dentry);
750 
751         inode = autofs4_get_inode(dir->i_sb, S_IFDIR | 0555);
752         if (!inode)
753                 return -ENOMEM;
754         d_add(dentry, inode);
755 
756         if (sbi->version < 5)
757                 autofs_set_leaf_automount_flags(dentry);
758 
759         dget(dentry);
760         atomic_inc(&ino->count);
761         p_ino = autofs4_dentry_ino(dentry->d_parent);
762         if (p_ino && !IS_ROOT(dentry))
763                 atomic_inc(&p_ino->count);
764         inc_nlink(dir);
765         dir->i_mtime = CURRENT_TIME;
766 
767         return 0;
768 }
769 
770 /* Get/set timeout ioctl() operation */
771 #ifdef CONFIG_COMPAT
772 static inline int autofs4_compat_get_set_timeout(struct autofs_sb_info *sbi,
773                                                  compat_ulong_t __user *p)
774 {
775         unsigned long ntimeout;
776         int rv;
777 
778         rv = get_user(ntimeout, p);
779         if (rv)
780                 goto error;
781 
782         rv = put_user(sbi->exp_timeout/HZ, p);
783         if (rv)
784                 goto error;
785 
786         if (ntimeout > UINT_MAX/HZ)
787                 sbi->exp_timeout = 0;
788         else
789                 sbi->exp_timeout = ntimeout * HZ;
790 
791         return 0;
792 error:
793         return rv;
794 }
795 #endif
796 
797 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
798                                           unsigned long __user *p)
799 {
800         unsigned long ntimeout;
801         int rv;
802 
803         rv = get_user(ntimeout, p);
804         if (rv)
805                 goto error;
806 
807         rv = put_user(sbi->exp_timeout/HZ, p);
808         if (rv)
809                 goto error;
810 
811         if (ntimeout > ULONG_MAX/HZ)
812                 sbi->exp_timeout = 0;
813         else
814                 sbi->exp_timeout = ntimeout * HZ;
815 
816         return 0;
817 error:
818         return rv;
819 }
820 
821 /* Return protocol version */
822 static inline int autofs4_get_protover(struct autofs_sb_info *sbi,
823                                        int __user *p)
824 {
825         return put_user(sbi->version, p);
826 }
827 
828 /* Return protocol sub version */
829 static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi,
830                                           int __user *p)
831 {
832         return put_user(sbi->sub_version, p);
833 }
834 
835 /*
836 * Tells the daemon whether it can umount the autofs mount.
837 */
838 static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
839 {
840         int status = 0;
841 
842         if (may_umount(mnt))
843                 status = 1;
844 
845         pr_debug("returning %d\n", status);
846 
847         status = put_user(status, p);
848 
849         return status;
850 }
851 
852 /* Identify autofs4_dentries - this is so we can tell if there's
853  * an extra dentry refcount or not.  We only hold a refcount on the
854  * dentry if its non-negative (ie, d_inode != NULL)
855  */
856 int is_autofs4_dentry(struct dentry *dentry)
857 {
858         return dentry && d_really_is_positive(dentry) &&
859                 dentry->d_op == &autofs4_dentry_operations &&
860                 dentry->d_fsdata != NULL;
861 }
862 
863 /*
864  * ioctl()'s on the root directory is the chief method for the daemon to
865  * generate kernel reactions
866  */
867 static int autofs4_root_ioctl_unlocked(struct inode *inode, struct file *filp,
868                                        unsigned int cmd, unsigned long arg)
869 {
870         struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
871         void __user *p = (void __user *)arg;
872 
873         pr_debug("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",
874                  cmd, arg, sbi, task_pgrp_nr(current));
875 
876         if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
877              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
878                 return -ENOTTY;
879 
880         if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
881                 return -EPERM;
882 
883         switch (cmd) {
884         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
885                 return autofs4_wait_release(sbi, (autofs_wqt_t) arg, 0);
886         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
887                 return autofs4_wait_release(sbi, (autofs_wqt_t) arg, -ENOENT);
888         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
889                 autofs4_catatonic_mode(sbi);
890                 return 0;
891         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
892                 return autofs4_get_protover(sbi, p);
893         case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
894                 return autofs4_get_protosubver(sbi, p);
895         case AUTOFS_IOC_SETTIMEOUT:
896                 return autofs4_get_set_timeout(sbi, p);
897 #ifdef CONFIG_COMPAT
898         case AUTOFS_IOC_SETTIMEOUT32:
899                 return autofs4_compat_get_set_timeout(sbi, p);
900 #endif
901 
902         case AUTOFS_IOC_ASKUMOUNT:
903                 return autofs4_ask_umount(filp->f_path.mnt, p);
904 
905         /* return a single thing to expire */
906         case AUTOFS_IOC_EXPIRE:
907                 return autofs4_expire_run(inode->i_sb,
908                                           filp->f_path.mnt, sbi, p);
909         /* same as above, but can send multiple expires through pipe */
910         case AUTOFS_IOC_EXPIRE_MULTI:
911                 return autofs4_expire_multi(inode->i_sb,
912                                             filp->f_path.mnt, sbi, p);
913 
914         default:
915                 return -EINVAL;
916         }
917 }
918 
919 static long autofs4_root_ioctl(struct file *filp,
920                                unsigned int cmd, unsigned long arg)
921 {
922         struct inode *inode = file_inode(filp);
923 
924         return autofs4_root_ioctl_unlocked(inode, filp, cmd, arg);
925 }
926 
927 #ifdef CONFIG_COMPAT
928 static long autofs4_root_compat_ioctl(struct file *filp,
929                                       unsigned int cmd, unsigned long arg)
930 {
931         struct inode *inode = file_inode(filp);
932         int ret;
933 
934         if (cmd == AUTOFS_IOC_READY || cmd == AUTOFS_IOC_FAIL)
935                 ret = autofs4_root_ioctl_unlocked(inode, filp, cmd, arg);
936         else
937                 ret = autofs4_root_ioctl_unlocked(inode, filp, cmd,
938                                               (unsigned long) compat_ptr(arg));
939 
940         return ret;
941 }
942 #endif
943 

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