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

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

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