fs/autofs4/root.c

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