~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

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

Version: ~ [ linux-5.5-rc6 ] ~ [ linux-5.4.11 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.95 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.164 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.209 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.209 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.81 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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 *, struct nameidata *);
 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         .readdir        = 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         .readdir        = 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         spin_lock(&dentry->d_lock);
128         if (!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {
129                 spin_unlock(&dentry->d_lock);
130                 spin_unlock(&sbi->lookup_lock);
131                 return -ENOENT;
132         }
133         spin_unlock(&dentry->d_lock);
134         spin_unlock(&sbi->lookup_lock);
135 
136 out:
137         return dcache_dir_open(inode, file);
138 }
139 
140 static void autofs4_dentry_release(struct dentry *de)
141 {
142         struct autofs_info *ino = autofs4_dentry_ino(de);
143         struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb);
144 
145         DPRINTK("releasing %p", de);
146 
147         if (!ino)
148                 return;
149 
150         if (sbi) {
151                 spin_lock(&sbi->lookup_lock);
152                 if (!list_empty(&ino->active))
153                         list_del(&ino->active);
154                 if (!list_empty(&ino->expiring))
155                         list_del(&ino->expiring);
156                 spin_unlock(&sbi->lookup_lock);
157         }
158 
159         autofs4_free_ino(ino);
160 }
161 
162 static struct dentry *autofs4_lookup_active(struct dentry *dentry)
163 {
164         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
165         struct dentry *parent = dentry->d_parent;
166         struct qstr *name = &dentry->d_name;
167         unsigned int len = name->len;
168         unsigned int hash = name->hash;
169         const unsigned char *str = name->name;
170         struct list_head *p, *head;
171 
172         spin_lock(&sbi->lookup_lock);
173         head = &sbi->active_list;
174         list_for_each(p, head) {
175                 struct autofs_info *ino;
176                 struct dentry *active;
177                 struct qstr *qstr;
178 
179                 ino = list_entry(p, struct autofs_info, active);
180                 active = ino->dentry;
181 
182                 spin_lock(&active->d_lock);
183 
184                 /* Already gone? */
185                 if (active->d_count == 0)
186                         goto next;
187 
188                 qstr = &active->d_name;
189 
190                 if (active->d_name.hash != hash)
191                         goto next;
192                 if (active->d_parent != parent)
193                         goto next;
194 
195                 if (qstr->len != len)
196                         goto next;
197                 if (memcmp(qstr->name, str, len))
198                         goto next;
199 
200                 if (d_unhashed(active)) {
201                         dget_dlock(active);
202                         spin_unlock(&active->d_lock);
203                         spin_unlock(&sbi->lookup_lock);
204                         return active;
205                 }
206 next:
207                 spin_unlock(&active->d_lock);
208         }
209         spin_unlock(&sbi->lookup_lock);
210 
211         return NULL;
212 }
213 
214 static struct dentry *autofs4_lookup_expiring(struct dentry *dentry)
215 {
216         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
217         struct dentry *parent = dentry->d_parent;
218         struct qstr *name = &dentry->d_name;
219         unsigned int len = name->len;
220         unsigned int hash = name->hash;
221         const unsigned char *str = name->name;
222         struct list_head *p, *head;
223 
224         spin_lock(&sbi->lookup_lock);
225         head = &sbi->expiring_list;
226         list_for_each(p, head) {
227                 struct autofs_info *ino;
228                 struct dentry *expiring;
229                 struct qstr *qstr;
230 
231                 ino = list_entry(p, struct autofs_info, expiring);
232                 expiring = ino->dentry;
233 
234                 spin_lock(&expiring->d_lock);
235 
236                 /* Bad luck, we've already been dentry_iput */
237                 if (!expiring->d_inode)
238                         goto next;
239 
240                 qstr = &expiring->d_name;
241 
242                 if (expiring->d_name.hash != hash)
243                         goto next;
244                 if (expiring->d_parent != parent)
245                         goto next;
246 
247                 if (qstr->len != len)
248                         goto next;
249                 if (memcmp(qstr->name, str, len))
250                         goto next;
251 
252                 if (d_unhashed(expiring)) {
253                         dget_dlock(expiring);
254                         spin_unlock(&expiring->d_lock);
255                         spin_unlock(&sbi->lookup_lock);
256                         return expiring;
257                 }
258 next:
259                 spin_unlock(&expiring->d_lock);
260         }
261         spin_unlock(&sbi->lookup_lock);
262 
263         return NULL;
264 }
265 
266 static int autofs4_mount_wait(struct dentry *dentry)
267 {
268         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
269         struct autofs_info *ino = autofs4_dentry_ino(dentry);
270         int status = 0;
271 
272         if (ino->flags & AUTOFS_INF_PENDING) {
273                 DPRINTK("waiting for mount name=%.*s",
274                         dentry->d_name.len, dentry->d_name.name);
275                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
276                 DPRINTK("mount wait done status=%d", status);
277         }
278         ino->last_used = jiffies;
279         return status;
280 }
281 
282 static int do_expire_wait(struct dentry *dentry)
283 {
284         struct dentry *expiring;
285 
286         expiring = autofs4_lookup_expiring(dentry);
287         if (!expiring)
288                 return autofs4_expire_wait(dentry);
289         else {
290                 /*
291                  * If we are racing with expire the request might not
292                  * be quite complete, but the directory has been removed
293                  * so it must have been successful, just wait for it.
294                  */
295                 autofs4_expire_wait(expiring);
296                 autofs4_del_expiring(expiring);
297                 dput(expiring);
298         }
299         return 0;
300 }
301 
302 static struct dentry *autofs4_mountpoint_changed(struct path *path)
303 {
304         struct dentry *dentry = path->dentry;
305         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
306 
307         /*
308          * If this is an indirect mount the dentry could have gone away
309          * as a result of an expire and a new one created.
310          */
311         if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) {
312                 struct dentry *parent = dentry->d_parent;
313                 struct autofs_info *ino;
314                 struct dentry *new = d_lookup(parent, &dentry->d_name);
315                 if (!new)
316                         return NULL;
317                 ino = autofs4_dentry_ino(new);
318                 ino->last_used = jiffies;
319                 dput(path->dentry);
320                 path->dentry = new;
321         }
322         return path->dentry;
323 }
324 
325 static struct vfsmount *autofs4_d_automount(struct path *path)
326 {
327         struct dentry *dentry = path->dentry;
328         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
329         struct autofs_info *ino = autofs4_dentry_ino(dentry);
330         int status;
331 
332         DPRINTK("dentry=%p %.*s",
333                 dentry, dentry->d_name.len, dentry->d_name.name);
334 
335         /* The daemon never triggers a mount. */
336         if (autofs4_oz_mode(sbi))
337                 return NULL;
338 
339         /*
340          * If an expire request is pending everyone must wait.
341          * If the expire fails we're still mounted so continue
342          * the follow and return. A return of -EAGAIN (which only
343          * happens with indirect mounts) means the expire completed
344          * and the directory was removed, so just go ahead and try
345          * the mount.
346          */
347         status = do_expire_wait(dentry);
348         if (status && status != -EAGAIN)
349                 return NULL;
350 
351         /* Callback to the daemon to perform the mount or wait */
352         spin_lock(&sbi->fs_lock);
353         if (ino->flags & AUTOFS_INF_PENDING) {
354                 spin_unlock(&sbi->fs_lock);
355                 status = autofs4_mount_wait(dentry);
356                 if (status)
357                         return ERR_PTR(status);
358                 spin_lock(&sbi->fs_lock);
359                 goto done;
360         }
361 
362         /*
363          * If the dentry is a symlink it's equivalent to a directory
364          * having d_mountpoint() true, so there's no need to call back
365          * to the daemon.
366          */
367         if (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode))
368                 goto done;
369         if (!d_mountpoint(dentry)) {
370                 /*
371                  * It's possible that user space hasn't removed directories
372                  * after umounting a rootless multi-mount, although it
373                  * should. For v5 have_submounts() is sufficient to handle
374                  * this because the leaves of the directory tree under the
375                  * mount never trigger mounts themselves (they have an autofs
376                  * trigger mount mounted on them). But v4 pseudo direct mounts
377                  * do need the leaves to to trigger mounts. In this case we
378                  * have no choice but to use the list_empty() check and
379                  * require user space behave.
380                  */
381                 if (sbi->version > 4) {
382                         if (have_submounts(dentry))
383                                 goto done;
384                 } else {
385                         spin_lock(&dentry->d_lock);
386                         if (!list_empty(&dentry->d_subdirs)) {
387                                 spin_unlock(&dentry->d_lock);
388                                 goto done;
389                         }
390                         spin_unlock(&dentry->d_lock);
391                 }
392                 ino->flags |= AUTOFS_INF_PENDING;
393                 spin_unlock(&sbi->fs_lock);
394                 status = autofs4_mount_wait(dentry);
395                 if (status)
396                         return ERR_PTR(status);
397                 spin_lock(&sbi->fs_lock);
398                 ino->flags &= ~AUTOFS_INF_PENDING;
399         }
400 done:
401         if (!(ino->flags & AUTOFS_INF_EXPIRING)) {
402                 /*
403                  * Any needed mounting has been completed and the path
404                  * updated so clear DCACHE_NEED_AUTOMOUNT so we don't
405                  * call ->d_automount() on rootless multi-mounts since
406                  * it can lead to an incorrect ELOOP error return.
407                  *
408                  * Only clear DMANAGED_AUTOMOUNT for rootless multi-mounts and
409                  * symlinks as in all other cases the dentry will be covered by
410                  * an actual mount so ->d_automount() won't be called during
411                  * the follow.
412                  */
413                 spin_lock(&dentry->d_lock);
414                 if ((!d_mountpoint(dentry) &&
415                     !list_empty(&dentry->d_subdirs)) ||
416                     (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode)))
417                         __managed_dentry_clear_automount(dentry);
418                 spin_unlock(&dentry->d_lock);
419         }
420         spin_unlock(&sbi->fs_lock);
421 
422         /* Mount succeeded, check if we ended up with a new dentry */
423         dentry = autofs4_mountpoint_changed(path);
424         if (!dentry)
425                 return ERR_PTR(-ENOENT);
426 
427         return NULL;
428 }
429 
430 int autofs4_d_manage(struct dentry *dentry, bool rcu_walk)
431 {
432         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
433 
434         DPRINTK("dentry=%p %.*s",
435                 dentry, dentry->d_name.len, dentry->d_name.name);
436 
437         /* The daemon never waits. */
438         if (autofs4_oz_mode(sbi)) {
439                 if (rcu_walk)
440                         return 0;
441                 if (!d_mountpoint(dentry))
442                         return -EISDIR;
443                 return 0;
444         }
445 
446         /* We need to sleep, so we need pathwalk to be in ref-mode */
447         if (rcu_walk)
448                 return -ECHILD;
449 
450         /* Wait for pending expires */
451         do_expire_wait(dentry);
452 
453         /*
454          * This dentry may be under construction so wait on mount
455          * completion.
456          */
457         return autofs4_mount_wait(dentry);
458 }
459 
460 /* Lookups in the root directory */
461 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
462 {
463         struct autofs_sb_info *sbi;
464         struct autofs_info *ino;
465         struct dentry *active;
466 
467         DPRINTK("name = %.*s", dentry->d_name.len, dentry->d_name.name);
468 
469         /* File name too long to exist */
470         if (dentry->d_name.len > NAME_MAX)
471                 return ERR_PTR(-ENAMETOOLONG);
472 
473         sbi = autofs4_sbi(dir->i_sb);
474 
475         DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
476                 current->pid, task_pgrp_nr(current), sbi->catatonic,
477                 autofs4_oz_mode(sbi));
478 
479         active = autofs4_lookup_active(dentry);
480         if (active) {
481                 return active;
482         } else {
483                 /*
484                  * A dentry that is not within the root can never trigger a
485                  * mount operation, unless the directory already exists, so we
486                  * can return fail immediately.  The daemon however does need
487                  * to create directories within the file system.
488                  */
489                 if (!autofs4_oz_mode(sbi) && !IS_ROOT(dentry->d_parent))
490                         return ERR_PTR(-ENOENT);
491 
492                 /* Mark entries in the root as mount triggers */
493                 if (autofs_type_indirect(sbi->type) && IS_ROOT(dentry->d_parent))
494                         __managed_dentry_set_managed(dentry);
495 
496                 ino = autofs4_new_ino(sbi);
497                 if (!ino)
498                         return ERR_PTR(-ENOMEM);
499 
500                 dentry->d_fsdata = ino;
501                 ino->dentry = dentry;
502 
503                 autofs4_add_active(dentry);
504 
505                 d_instantiate(dentry, NULL);
506         }
507         return NULL;
508 }
509 
510 static int autofs4_dir_symlink(struct inode *dir, 
511                                struct dentry *dentry,
512                                const char *symname)
513 {
514         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
515         struct autofs_info *ino = autofs4_dentry_ino(dentry);
516         struct autofs_info *p_ino;
517         struct inode *inode;
518         size_t size = strlen(symname);
519         char *cp;
520 
521         DPRINTK("%s <- %.*s", symname,
522                 dentry->d_name.len, dentry->d_name.name);
523 
524         if (!autofs4_oz_mode(sbi))
525                 return -EACCES;
526 
527         BUG_ON(!ino);
528 
529         autofs4_clean_ino(ino);
530 
531         autofs4_del_active(dentry);
532 
533         cp = kmalloc(size + 1, GFP_KERNEL);
534         if (!cp)
535                 return -ENOMEM;
536 
537         strcpy(cp, symname);
538 
539         inode = autofs4_get_inode(dir->i_sb, S_IFLNK | 0555);
540         if (!inode) {
541                 kfree(cp);
542                 if (!dentry->d_fsdata)
543                         kfree(ino);
544                 return -ENOMEM;
545         }
546         inode->i_private = cp;
547         inode->i_size = size;
548         d_add(dentry, inode);
549 
550         dget(dentry);
551         atomic_inc(&ino->count);
552         p_ino = autofs4_dentry_ino(dentry->d_parent);
553         if (p_ino && dentry->d_parent != dentry)
554                 atomic_inc(&p_ino->count);
555 
556         dir->i_mtime = CURRENT_TIME;
557 
558         return 0;
559 }
560 
561 /*
562  * NOTE!
563  *
564  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
565  * that the file no longer exists. However, doing that means that the
566  * VFS layer can turn the dentry into a negative dentry.  We don't want
567  * this, because the unlink is probably the result of an expire.
568  * We simply d_drop it and add it to a expiring list in the super block,
569  * which allows the dentry lookup to check for an incomplete expire.
570  *
571  * If a process is blocked on the dentry waiting for the expire to finish,
572  * it will invalidate the dentry and try to mount with a new one.
573  *
574  * Also see autofs4_dir_rmdir()..
575  */
576 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
577 {
578         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
579         struct autofs_info *ino = autofs4_dentry_ino(dentry);
580         struct autofs_info *p_ino;
581         
582         /* This allows root to remove symlinks */
583         if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
584                 return -EACCES;
585 
586         if (atomic_dec_and_test(&ino->count)) {
587                 p_ino = autofs4_dentry_ino(dentry->d_parent);
588                 if (p_ino && dentry->d_parent != dentry)
589                         atomic_dec(&p_ino->count);
590         }
591         dput(ino->dentry);
592 
593         dentry->d_inode->i_size = 0;
594         clear_nlink(dentry->d_inode);
595 
596         dir->i_mtime = CURRENT_TIME;
597 
598         spin_lock(&sbi->lookup_lock);
599         __autofs4_add_expiring(dentry);
600         spin_lock(&dentry->d_lock);
601         __d_drop(dentry);
602         spin_unlock(&dentry->d_lock);
603         spin_unlock(&sbi->lookup_lock);
604 
605         return 0;
606 }
607 
608 /*
609  * Version 4 of autofs provides a pseudo direct mount implementation
610  * that relies on directories at the leaves of a directory tree under
611  * an indirect mount to trigger mounts. To allow for this we need to
612  * set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves
613  * of the directory tree. There is no need to clear the automount flag
614  * following a mount or restore it after an expire because these mounts
615  * are always covered. However, it is necessary to ensure that these
616  * flags are clear on non-empty directories to avoid unnecessary calls
617  * during path walks.
618  */
619 static void autofs_set_leaf_automount_flags(struct dentry *dentry)
620 {
621         struct dentry *parent;
622 
623         /* root and dentrys in the root are already handled */
624         if (IS_ROOT(dentry->d_parent))
625                 return;
626 
627         managed_dentry_set_managed(dentry);
628 
629         parent = dentry->d_parent;
630         /* only consider parents below dentrys in the root */
631         if (IS_ROOT(parent->d_parent))
632                 return;
633         managed_dentry_clear_managed(parent);
634         return;
635 }
636 
637 static void autofs_clear_leaf_automount_flags(struct dentry *dentry)
638 {
639         struct list_head *d_child;
640         struct dentry *parent;
641 
642         /* flags for dentrys in the root are handled elsewhere */
643         if (IS_ROOT(dentry->d_parent))
644                 return;
645 
646         managed_dentry_clear_managed(dentry);
647 
648         parent = dentry->d_parent;
649         /* only consider parents below dentrys in the root */
650         if (IS_ROOT(parent->d_parent))
651                 return;
652         d_child = &dentry->d_u.d_child;
653         /* Set parent managed if it's becoming empty */
654         if (d_child->next == &parent->d_subdirs &&
655             d_child->prev == &parent->d_subdirs)
656                 managed_dentry_set_managed(parent);
657         return;
658 }
659 
660 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
661 {
662         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
663         struct autofs_info *ino = autofs4_dentry_ino(dentry);
664         struct autofs_info *p_ino;
665         
666         DPRINTK("dentry %p, removing %.*s",
667                 dentry, dentry->d_name.len, dentry->d_name.name);
668 
669         if (!autofs4_oz_mode(sbi))
670                 return -EACCES;
671 
672         spin_lock(&sbi->lookup_lock);
673         spin_lock(&dentry->d_lock);
674         if (!list_empty(&dentry->d_subdirs)) {
675                 spin_unlock(&dentry->d_lock);
676                 spin_unlock(&sbi->lookup_lock);
677                 return -ENOTEMPTY;
678         }
679         __autofs4_add_expiring(dentry);
680         __d_drop(dentry);
681         spin_unlock(&dentry->d_lock);
682         spin_unlock(&sbi->lookup_lock);
683 
684         if (sbi->version < 5)
685                 autofs_clear_leaf_automount_flags(dentry);
686 
687         if (atomic_dec_and_test(&ino->count)) {
688                 p_ino = autofs4_dentry_ino(dentry->d_parent);
689                 if (p_ino && dentry->d_parent != dentry)
690                         atomic_dec(&p_ino->count);
691         }
692         dput(ino->dentry);
693         dentry->d_inode->i_size = 0;
694         clear_nlink(dentry->d_inode);
695 
696         if (dir->i_nlink)
697                 drop_nlink(dir);
698 
699         return 0;
700 }
701 
702 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
703 {
704         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
705         struct autofs_info *ino = autofs4_dentry_ino(dentry);
706         struct autofs_info *p_ino;
707         struct inode *inode;
708 
709         if (!autofs4_oz_mode(sbi))
710                 return -EACCES;
711 
712         DPRINTK("dentry %p, creating %.*s",
713                 dentry, dentry->d_name.len, dentry->d_name.name);
714 
715         BUG_ON(!ino);
716 
717         autofs4_clean_ino(ino);
718 
719         autofs4_del_active(dentry);
720 
721         inode = autofs4_get_inode(dir->i_sb, S_IFDIR | 0555);
722         if (!inode)
723                 return -ENOMEM;
724         d_add(dentry, inode);
725 
726         if (sbi->version < 5)
727                 autofs_set_leaf_automount_flags(dentry);
728 
729         dget(dentry);
730         atomic_inc(&ino->count);
731         p_ino = autofs4_dentry_ino(dentry->d_parent);
732         if (p_ino && dentry->d_parent != dentry)
733                 atomic_inc(&p_ino->count);
734         inc_nlink(dir);
735         dir->i_mtime = CURRENT_TIME;
736 
737         return 0;
738 }
739 
740 /* Get/set timeout ioctl() operation */
741 #ifdef CONFIG_COMPAT
742 static inline int autofs4_compat_get_set_timeout(struct autofs_sb_info *sbi,
743                                          compat_ulong_t __user *p)
744 {
745         int rv;
746         unsigned long ntimeout;
747 
748         if ((rv = get_user(ntimeout, p)) ||
749              (rv = put_user(sbi->exp_timeout/HZ, p)))
750                 return rv;
751 
752         if (ntimeout > UINT_MAX/HZ)
753                 sbi->exp_timeout = 0;
754         else
755                 sbi->exp_timeout = ntimeout * HZ;
756 
757         return 0;
758 }
759 #endif
760 
761 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
762                                          unsigned long __user *p)
763 {
764         int rv;
765         unsigned long ntimeout;
766 
767         if ((rv = get_user(ntimeout, p)) ||
768              (rv = put_user(sbi->exp_timeout/HZ, p)))
769                 return rv;
770 
771         if (ntimeout > ULONG_MAX/HZ)
772                 sbi->exp_timeout = 0;
773         else
774                 sbi->exp_timeout = ntimeout * HZ;
775 
776         return 0;
777 }
778 
779 /* Return protocol version */
780 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
781 {
782         return put_user(sbi->version, p);
783 }
784 
785 /* Return protocol sub version */
786 static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
787 {
788         return put_user(sbi->sub_version, p);
789 }
790 
791 /*
792 * Tells the daemon whether it can umount the autofs mount.
793 */
794 static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
795 {
796         int status = 0;
797 
798         if (may_umount(mnt))
799                 status = 1;
800 
801         DPRINTK("returning %d", status);
802 
803         status = put_user(status, p);
804 
805         return status;
806 }
807 
808 /* Identify autofs4_dentries - this is so we can tell if there's
809    an extra dentry refcount or not.  We only hold a refcount on the
810    dentry if its non-negative (ie, d_inode != NULL)
811 */
812 int is_autofs4_dentry(struct dentry *dentry)
813 {
814         return dentry && dentry->d_inode &&
815                 dentry->d_op == &autofs4_dentry_operations &&
816                 dentry->d_fsdata != NULL;
817 }
818 
819 /*
820  * ioctl()'s on the root directory is the chief method for the daemon to
821  * generate kernel reactions
822  */
823 static int autofs4_root_ioctl_unlocked(struct inode *inode, struct file *filp,
824                                        unsigned int cmd, unsigned long arg)
825 {
826         struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
827         void __user *p = (void __user *)arg;
828 
829         DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
830                 cmd,arg,sbi,task_pgrp_nr(current));
831 
832         if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
833              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
834                 return -ENOTTY;
835         
836         if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
837                 return -EPERM;
838         
839         switch(cmd) {
840         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
841                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
842         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
843                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
844         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
845                 autofs4_catatonic_mode(sbi);
846                 return 0;
847         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
848                 return autofs4_get_protover(sbi, p);
849         case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
850                 return autofs4_get_protosubver(sbi, p);
851         case AUTOFS_IOC_SETTIMEOUT:
852                 return autofs4_get_set_timeout(sbi, p);
853 #ifdef CONFIG_COMPAT
854         case AUTOFS_IOC_SETTIMEOUT32:
855                 return autofs4_compat_get_set_timeout(sbi, p);
856 #endif
857 
858         case AUTOFS_IOC_ASKUMOUNT:
859                 return autofs4_ask_umount(filp->f_path.mnt, p);
860 
861         /* return a single thing to expire */
862         case AUTOFS_IOC_EXPIRE:
863                 return autofs4_expire_run(inode->i_sb,filp->f_path.mnt,sbi, p);
864         /* same as above, but can send multiple expires through pipe */
865         case AUTOFS_IOC_EXPIRE_MULTI:
866                 return autofs4_expire_multi(inode->i_sb,filp->f_path.mnt,sbi, p);
867 
868         default:
869                 return -ENOSYS;
870         }
871 }
872 
873 static long autofs4_root_ioctl(struct file *filp,
874                                unsigned int cmd, unsigned long arg)
875 {
876         struct inode *inode = filp->f_dentry->d_inode;
877         return autofs4_root_ioctl_unlocked(inode, filp, cmd, arg);
878 }
879 
880 #ifdef CONFIG_COMPAT
881 static long autofs4_root_compat_ioctl(struct file *filp,
882                              unsigned int cmd, unsigned long arg)
883 {
884         struct inode *inode = filp->f_path.dentry->d_inode;
885         int ret;
886 
887         if (cmd == AUTOFS_IOC_READY || cmd == AUTOFS_IOC_FAIL)
888                 ret = autofs4_root_ioctl_unlocked(inode, filp, cmd, arg);
889         else
890                 ret = autofs4_root_ioctl_unlocked(inode, filp, cmd,
891                         (unsigned long)compat_ptr(arg));
892 
893         return ret;
894 }
895 #endif
896 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp