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