fs/autofs4/root.c

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