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

Version: ~ [ linux-5.12-rc7 ] ~ [ linux-5.11.13 ] ~ [ linux-5.10.29 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.111 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.186 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.230 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.266 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.266 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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 %pd", 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         DPRINTK("releasing %p", 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 (!expiring->d_inode)
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                 DPRINTK("waiting for mount name=%pd", dentry);
282                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
283                 DPRINTK("mount wait done status=%d", 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 = d_lookup(parent, &dentry->d_name);
324                 if (!new)
325                         return NULL;
326                 ino = autofs4_dentry_ino(new);
327                 ino->last_used = jiffies;
328                 dput(path->dentry);
329                 path->dentry = new;
330         }
331         return path->dentry;
332 }
333 
334 static struct vfsmount *autofs4_d_automount(struct path *path)
335 {
336         struct dentry *dentry = path->dentry;
337         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
338         struct autofs_info *ino = autofs4_dentry_ino(dentry);
339         int status;
340 
341         DPRINTK("dentry=%p %pd", dentry, dentry);
342 
343         /* The daemon never triggers a mount. */
344         if (autofs4_oz_mode(sbi))
345                 return NULL;
346 
347         /*
348          * If an expire request is pending everyone must wait.
349          * If the expire fails we're still mounted so continue
350          * the follow and return. A return of -EAGAIN (which only
351          * happens with indirect mounts) means the expire completed
352          * and the directory was removed, so just go ahead and try
353          * the mount.
354          */
355         status = do_expire_wait(dentry, 0);
356         if (status && status != -EAGAIN)
357                 return NULL;
358 
359         /* Callback to the daemon to perform the mount or wait */
360         spin_lock(&sbi->fs_lock);
361         if (ino->flags & AUTOFS_INF_PENDING) {
362                 spin_unlock(&sbi->fs_lock);
363                 status = autofs4_mount_wait(dentry, 0);
364                 if (status)
365                         return ERR_PTR(status);
366                 goto done;
367         }
368 
369         /*
370          * If the dentry is a symlink it's equivalent to a directory
371          * having d_mountpoint() true, so there's no need to call back
372          * to the daemon.
373          */
374         if (dentry->d_inode && d_is_symlink(dentry)) {
375                 spin_unlock(&sbi->fs_lock);
376                 goto done;
377         }
378 
379         if (!d_mountpoint(dentry)) {
380                 /*
381                  * It's possible that user space hasn't removed directories
382                  * after umounting a rootless multi-mount, although it
383                  * should. For v5 have_submounts() is sufficient to handle
384                  * this because the leaves of the directory tree under the
385                  * mount never trigger mounts themselves (they have an autofs
386                  * trigger mount mounted on them). But v4 pseudo direct mounts
387                  * do need the leaves to trigger mounts. In this case we
388                  * have no choice but to use the list_empty() check and
389                  * require user space behave.
390                  */
391                 if (sbi->version > 4) {
392                         if (have_submounts(dentry)) {
393                                 spin_unlock(&sbi->fs_lock);
394                                 goto done;
395                         }
396                 } else {
397                         if (!simple_empty(dentry)) {
398                                 spin_unlock(&sbi->fs_lock);
399                                 goto done;
400                         }
401                 }
402                 ino->flags |= AUTOFS_INF_PENDING;
403                 spin_unlock(&sbi->fs_lock);
404                 status = autofs4_mount_wait(dentry, 0);
405                 spin_lock(&sbi->fs_lock);
406                 ino->flags &= ~AUTOFS_INF_PENDING;
407                 if (status) {
408                         spin_unlock(&sbi->fs_lock);
409                         return ERR_PTR(status);
410                 }
411         }
412         spin_unlock(&sbi->fs_lock);
413 done:
414         /* Mount succeeded, check if we ended up with a new dentry */
415         dentry = autofs4_mountpoint_changed(path);
416         if (!dentry)
417                 return ERR_PTR(-ENOENT);
418 
419         return NULL;
420 }
421 
422 static int autofs4_d_manage(struct dentry *dentry, bool rcu_walk)
423 {
424         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
425         struct autofs_info *ino = autofs4_dentry_ino(dentry);
426         int status;
427 
428         DPRINTK("dentry=%p %pd", dentry, dentry);
429 
430         /* The daemon never waits. */
431         if (autofs4_oz_mode(sbi)) {
432                 if (!d_mountpoint(dentry))
433                         return -EISDIR;
434                 return 0;
435         }
436 
437         /* Wait for pending expires */
438         if (do_expire_wait(dentry, rcu_walk) == -ECHILD)
439                 return -ECHILD;
440 
441         /*
442          * This dentry may be under construction so wait on mount
443          * completion.
444          */
445         status = autofs4_mount_wait(dentry, rcu_walk);
446         if (status)
447                 return status;
448 
449         if (rcu_walk) {
450                 /* We don't need fs_lock in rcu_walk mode,
451                  * just testing 'AUTOFS_INFO_NO_RCU' is enough.
452                  * simple_empty() takes a spinlock, so leave it
453                  * to last.
454                  * We only return -EISDIR when certain this isn't
455                  * a mount-trap.
456                  */
457                 struct inode *inode;
458                 if (ino->flags & (AUTOFS_INF_EXPIRING | AUTOFS_INF_NO_RCU))
459                         return 0;
460                 if (d_mountpoint(dentry))
461                         return 0;
462                 inode = ACCESS_ONCE(dentry->d_inode);
463                 if (inode && S_ISLNK(inode->i_mode))
464                         return -EISDIR;
465                 if (list_empty(&dentry->d_subdirs))
466                         return 0;
467                 if (!simple_empty(dentry))
468                         return -EISDIR;
469                 return 0;
470         }
471 
472         spin_lock(&sbi->fs_lock);
473         /*
474          * If the dentry has been selected for expire while we slept
475          * on the lock then it might go away. We'll deal with that in
476          * ->d_automount() and wait on a new mount if the expire
477          * succeeds or return here if it doesn't (since there's no
478          * mount to follow with a rootless multi-mount).
479          */
480         if (!(ino->flags & AUTOFS_INF_EXPIRING)) {
481                 /*
482                  * Any needed mounting has been completed and the path
483                  * updated so check if this is a rootless multi-mount so
484                  * we can avoid needless calls ->d_automount() and avoid
485                  * an incorrect ELOOP error return.
486                  */
487                 if ((!d_mountpoint(dentry) && !simple_empty(dentry)) ||
488                     (dentry->d_inode && d_is_symlink(dentry)))
489                         status = -EISDIR;
490         }
491         spin_unlock(&sbi->fs_lock);
492 
493         return status;
494 }
495 
496 /* Lookups in the root directory */
497 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
498 {
499         struct autofs_sb_info *sbi;
500         struct autofs_info *ino;
501         struct dentry *active;
502 
503         DPRINTK("name = %pd", dentry);
504 
505         /* File name too long to exist */
506         if (dentry->d_name.len > NAME_MAX)
507                 return ERR_PTR(-ENAMETOOLONG);
508 
509         sbi = autofs4_sbi(dir->i_sb);
510 
511         DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
512                 current->pid, task_pgrp_nr(current), sbi->catatonic,
513                 autofs4_oz_mode(sbi));
514 
515         active = autofs4_lookup_active(dentry);
516         if (active) {
517                 return active;
518         } else {
519                 /*
520                  * A dentry that is not within the root can never trigger a
521                  * mount operation, unless the directory already exists, so we
522                  * can return fail immediately.  The daemon however does need
523                  * to create directories within the file system.
524                  */
525                 if (!autofs4_oz_mode(sbi) && !IS_ROOT(dentry->d_parent))
526                         return ERR_PTR(-ENOENT);
527 
528                 /* Mark entries in the root as mount triggers */
529                 if (autofs_type_indirect(sbi->type) && IS_ROOT(dentry->d_parent))
530                         __managed_dentry_set_managed(dentry);
531 
532                 ino = autofs4_new_ino(sbi);
533                 if (!ino)
534                         return ERR_PTR(-ENOMEM);
535 
536                 dentry->d_fsdata = ino;
537                 ino->dentry = dentry;
538 
539                 autofs4_add_active(dentry);
540 
541                 d_instantiate(dentry, NULL);
542         }
543         return NULL;
544 }
545 
546 static int autofs4_dir_symlink(struct inode *dir, 
547                                struct dentry *dentry,
548                                const char *symname)
549 {
550         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
551         struct autofs_info *ino = autofs4_dentry_ino(dentry);
552         struct autofs_info *p_ino;
553         struct inode *inode;
554         size_t size = strlen(symname);
555         char *cp;
556 
557         DPRINTK("%s <- %pd", symname, dentry);
558 
559         if (!autofs4_oz_mode(sbi))
560                 return -EACCES;
561 
562         BUG_ON(!ino);
563 
564         autofs4_clean_ino(ino);
565 
566         autofs4_del_active(dentry);
567 
568         cp = kmalloc(size + 1, GFP_KERNEL);
569         if (!cp)
570                 return -ENOMEM;
571 
572         strcpy(cp, symname);
573 
574         inode = autofs4_get_inode(dir->i_sb, S_IFLNK | 0555);
575         if (!inode) {
576                 kfree(cp);
577                 if (!dentry->d_fsdata)
578                         kfree(ino);
579                 return -ENOMEM;
580         }
581         inode->i_private = cp;
582         inode->i_size = size;
583         d_add(dentry, inode);
584 
585         dget(dentry);
586         atomic_inc(&ino->count);
587         p_ino = autofs4_dentry_ino(dentry->d_parent);
588         if (p_ino && !IS_ROOT(dentry))
589                 atomic_inc(&p_ino->count);
590 
591         dir->i_mtime = CURRENT_TIME;
592 
593         return 0;
594 }
595 
596 /*
597  * NOTE!
598  *
599  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
600  * that the file no longer exists. However, doing that means that the
601  * VFS layer can turn the dentry into a negative dentry.  We don't want
602  * this, because the unlink is probably the result of an expire.
603  * We simply d_drop it and add it to a expiring list in the super block,
604  * which allows the dentry lookup to check for an incomplete expire.
605  *
606  * If a process is blocked on the dentry waiting for the expire to finish,
607  * it will invalidate the dentry and try to mount with a new one.
608  *
609  * Also see autofs4_dir_rmdir()..
610  */
611 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
612 {
613         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
614         struct autofs_info *ino = autofs4_dentry_ino(dentry);
615         struct autofs_info *p_ino;
616         
617         /* This allows root to remove symlinks */
618         if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
619                 return -EPERM;
620 
621         if (atomic_dec_and_test(&ino->count)) {
622                 p_ino = autofs4_dentry_ino(dentry->d_parent);
623                 if (p_ino && !IS_ROOT(dentry))
624                         atomic_dec(&p_ino->count);
625         }
626         dput(ino->dentry);
627 
628         dentry->d_inode->i_size = 0;
629         clear_nlink(dentry->d_inode);
630 
631         dir->i_mtime = CURRENT_TIME;
632 
633         spin_lock(&sbi->lookup_lock);
634         __autofs4_add_expiring(dentry);
635         d_drop(dentry);
636         spin_unlock(&sbi->lookup_lock);
637 
638         return 0;
639 }
640 
641 /*
642  * Version 4 of autofs provides a pseudo direct mount implementation
643  * that relies on directories at the leaves of a directory tree under
644  * an indirect mount to trigger mounts. To allow for this we need to
645  * set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves
646  * of the directory tree. There is no need to clear the automount flag
647  * following a mount or restore it after an expire because these mounts
648  * are always covered. However, it is necessary to ensure that these
649  * flags are clear on non-empty directories to avoid unnecessary calls
650  * during path walks.
651  */
652 static void autofs_set_leaf_automount_flags(struct dentry *dentry)
653 {
654         struct dentry *parent;
655 
656         /* root and dentrys in the root are already handled */
657         if (IS_ROOT(dentry->d_parent))
658                 return;
659 
660         managed_dentry_set_managed(dentry);
661 
662         parent = dentry->d_parent;
663         /* only consider parents below dentrys in the root */
664         if (IS_ROOT(parent->d_parent))
665                 return;
666         managed_dentry_clear_managed(parent);
667         return;
668 }
669 
670 static void autofs_clear_leaf_automount_flags(struct dentry *dentry)
671 {
672         struct list_head *d_child;
673         struct dentry *parent;
674 
675         /* flags for dentrys in the root are handled elsewhere */
676         if (IS_ROOT(dentry->d_parent))
677                 return;
678 
679         managed_dentry_clear_managed(dentry);
680 
681         parent = dentry->d_parent;
682         /* only consider parents below dentrys in the root */
683         if (IS_ROOT(parent->d_parent))
684                 return;
685         d_child = &dentry->d_child;
686         /* Set parent managed if it's becoming empty */
687         if (d_child->next == &parent->d_subdirs &&
688             d_child->prev == &parent->d_subdirs)
689                 managed_dentry_set_managed(parent);
690         return;
691 }
692 
693 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
694 {
695         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
696         struct autofs_info *ino = autofs4_dentry_ino(dentry);
697         struct autofs_info *p_ino;
698         
699         DPRINTK("dentry %p, removing %pd", dentry, dentry);
700 
701         if (!autofs4_oz_mode(sbi))
702                 return -EACCES;
703 
704         spin_lock(&sbi->lookup_lock);
705         if (!simple_empty(dentry)) {
706                 spin_unlock(&sbi->lookup_lock);
707                 return -ENOTEMPTY;
708         }
709         __autofs4_add_expiring(dentry);
710         d_drop(dentry);
711         spin_unlock(&sbi->lookup_lock);
712 
713         if (sbi->version < 5)
714                 autofs_clear_leaf_automount_flags(dentry);
715 
716         if (atomic_dec_and_test(&ino->count)) {
717                 p_ino = autofs4_dentry_ino(dentry->d_parent);
718                 if (p_ino && dentry->d_parent != dentry)
719                         atomic_dec(&p_ino->count);
720         }
721         dput(ino->dentry);
722         dentry->d_inode->i_size = 0;
723         clear_nlink(dentry->d_inode);
724 
725         if (dir->i_nlink)
726                 drop_nlink(dir);
727 
728         return 0;
729 }
730 
731 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
732 {
733         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
734         struct autofs_info *ino = autofs4_dentry_ino(dentry);
735         struct autofs_info *p_ino;
736         struct inode *inode;
737 
738         if (!autofs4_oz_mode(sbi))
739                 return -EACCES;
740 
741         DPRINTK("dentry %p, creating %pd", dentry, dentry);
742 
743         BUG_ON(!ino);
744 
745         autofs4_clean_ino(ino);
746 
747         autofs4_del_active(dentry);
748 
749         inode = autofs4_get_inode(dir->i_sb, S_IFDIR | 0555);
750         if (!inode)
751                 return -ENOMEM;
752         d_add(dentry, inode);
753 
754         if (sbi->version < 5)
755                 autofs_set_leaf_automount_flags(dentry);
756 
757         dget(dentry);
758         atomic_inc(&ino->count);
759         p_ino = autofs4_dentry_ino(dentry->d_parent);
760         if (p_ino && !IS_ROOT(dentry))
761                 atomic_inc(&p_ino->count);
762         inc_nlink(dir);
763         dir->i_mtime = CURRENT_TIME;
764 
765         return 0;
766 }
767 
768 /* Get/set timeout ioctl() operation */
769 #ifdef CONFIG_COMPAT
770 static inline int autofs4_compat_get_set_timeout(struct autofs_sb_info *sbi,
771                                          compat_ulong_t __user *p)
772 {
773         int rv;
774         unsigned long ntimeout;
775 
776         if ((rv = get_user(ntimeout, p)) ||
777              (rv = put_user(sbi->exp_timeout/HZ, p)))
778                 return rv;
779 
780         if (ntimeout > UINT_MAX/HZ)
781                 sbi->exp_timeout = 0;
782         else
783                 sbi->exp_timeout = ntimeout * HZ;
784 
785         return 0;
786 }
787 #endif
788 
789 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
790                                          unsigned long __user *p)
791 {
792         int rv;
793         unsigned long ntimeout;
794 
795         if ((rv = get_user(ntimeout, p)) ||
796              (rv = put_user(sbi->exp_timeout/HZ, p)))
797                 return rv;
798 
799         if (ntimeout > ULONG_MAX/HZ)
800                 sbi->exp_timeout = 0;
801         else
802                 sbi->exp_timeout = ntimeout * HZ;
803 
804         return 0;
805 }
806 
807 /* Return protocol version */
808 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
809 {
810         return put_user(sbi->version, p);
811 }
812 
813 /* Return protocol sub version */
814 static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
815 {
816         return put_user(sbi->sub_version, p);
817 }
818 
819 /*
820 * Tells the daemon whether it can umount the autofs mount.
821 */
822 static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
823 {
824         int status = 0;
825 
826         if (may_umount(mnt))
827                 status = 1;
828 
829         DPRINTK("returning %d", status);
830 
831         status = put_user(status, p);
832 
833         return status;
834 }
835 
836 /* Identify autofs4_dentries - this is so we can tell if there's
837    an extra dentry refcount or not.  We only hold a refcount on the
838    dentry if its non-negative (ie, d_inode != NULL)
839 */
840 int is_autofs4_dentry(struct dentry *dentry)
841 {
842         return dentry && dentry->d_inode &&
843                 dentry->d_op == &autofs4_dentry_operations &&
844                 dentry->d_fsdata != NULL;
845 }
846 
847 /*
848  * ioctl()'s on the root directory is the chief method for the daemon to
849  * generate kernel reactions
850  */
851 static int autofs4_root_ioctl_unlocked(struct inode *inode, struct file *filp,
852                                        unsigned int cmd, unsigned long arg)
853 {
854         struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
855         void __user *p = (void __user *)arg;
856 
857         DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
858                 cmd,arg,sbi,task_pgrp_nr(current));
859 
860         if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
861              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
862                 return -ENOTTY;
863         
864         if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
865                 return -EPERM;
866         
867         switch(cmd) {
868         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
869                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
870         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
871                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
872         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
873                 autofs4_catatonic_mode(sbi);
874                 return 0;
875         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
876                 return autofs4_get_protover(sbi, p);
877         case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
878                 return autofs4_get_protosubver(sbi, p);
879         case AUTOFS_IOC_SETTIMEOUT:
880                 return autofs4_get_set_timeout(sbi, p);
881 #ifdef CONFIG_COMPAT
882         case AUTOFS_IOC_SETTIMEOUT32:
883                 return autofs4_compat_get_set_timeout(sbi, p);
884 #endif
885 
886         case AUTOFS_IOC_ASKUMOUNT:
887                 return autofs4_ask_umount(filp->f_path.mnt, p);
888 
889         /* return a single thing to expire */
890         case AUTOFS_IOC_EXPIRE:
891                 return autofs4_expire_run(inode->i_sb,filp->f_path.mnt,sbi, p);
892         /* same as above, but can send multiple expires through pipe */
893         case AUTOFS_IOC_EXPIRE_MULTI:
894                 return autofs4_expire_multi(inode->i_sb,filp->f_path.mnt,sbi, p);
895 
896         default:
897                 return -ENOSYS;
898         }
899 }
900 
901 static long autofs4_root_ioctl(struct file *filp,
902                                unsigned int cmd, unsigned long arg)
903 {
904         struct inode *inode = file_inode(filp);
905         return autofs4_root_ioctl_unlocked(inode, filp, cmd, arg);
906 }
907 
908 #ifdef CONFIG_COMPAT
909 static long autofs4_root_compat_ioctl(struct file *filp,
910                              unsigned int cmd, unsigned long arg)
911 {
912         struct inode *inode = file_inode(filp);
913         int ret;
914 
915         if (cmd == AUTOFS_IOC_READY || cmd == AUTOFS_IOC_FAIL)
916                 ret = autofs4_root_ioctl_unlocked(inode, filp, cmd, arg);
917         else
918                 ret = autofs4_root_ioctl_unlocked(inode, filp, cmd,
919                         (unsigned long)compat_ptr(arg));
920 
921         return ret;
922 }
923 #endif
924 

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