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 2001-2003 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/errno.h>
  16 #include <linux/stat.h>
  17 #include <linux/param.h>
  18 #include <linux/time.h>
  19 #include <linux/smp_lock.h>
  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 *,int);
  26 static int autofs4_root_ioctl(struct inode *, struct file *,unsigned int,unsigned long);
  27 static int autofs4_dir_open(struct inode *inode, struct file *file);
  28 static int autofs4_dir_close(struct inode *inode, struct file *file);
  29 static int autofs4_dir_readdir(struct file * filp, void * dirent, filldir_t filldir);
  30 static int autofs4_root_readdir(struct file * filp, void * dirent, filldir_t filldir);
  31 static struct dentry *autofs4_lookup(struct inode *,struct dentry *, struct nameidata *);
  32 static int autofs4_dcache_readdir(struct file *, void *, filldir_t);
  33
  34 struct file_operations autofs4_root_operations = {
  35         .open           = dcache_dir_open,
  36         .release        = dcache_dir_close,
  37         .read           = generic_read_dir,
  38         .readdir        = autofs4_root_readdir,
  39         .ioctl          = autofs4_root_ioctl,
  40 };
  41
  42 struct file_operations autofs4_dir_operations = {
  43         .open           = autofs4_dir_open,
  44         .release        = autofs4_dir_close,
  45         .read           = generic_read_dir,
  46         .readdir        = autofs4_dir_readdir,
  47 };
  48
  49 struct inode_operations autofs4_root_inode_operations = {
  50         .lookup         = autofs4_lookup,
  51         .unlink         = autofs4_dir_unlink,
  52         .symlink        = autofs4_dir_symlink,
  53         .mkdir          = autofs4_dir_mkdir,
  54         .rmdir          = autofs4_dir_rmdir,
  55 };
  56
  57 struct inode_operations autofs4_dir_inode_operations = {
  58         .lookup         = autofs4_lookup,
  59         .unlink         = autofs4_dir_unlink,
  60         .symlink        = autofs4_dir_symlink,
  61         .mkdir          = autofs4_dir_mkdir,
  62         .rmdir          = autofs4_dir_rmdir,
  63 };
  64
  65 static int autofs4_root_readdir(struct file *file, void *dirent,
  66                                 filldir_t filldir)
  67 {
  68         struct autofs_sb_info *sbi = autofs4_sbi(file->f_dentry->d_sb);
  69         int oz_mode = autofs4_oz_mode(sbi);
  70
  71         DPRINTK("called, filp->f_pos = %lld", file->f_pos);
  72
  73         /*
  74          * Don't set reghost flag if:
  75          * 1) f_pos is larger than zero -- we've already been here.
  76          * 2) we haven't even enabled reghosting in the 1st place.
  77          * 3) this is the daemon doing a readdir
  78          */
  79         if (oz_mode && file->f_pos == 0 && sbi->reghost_enabled)
  80                 sbi->needs_reghost = 1;
  81
  82         DPRINTK("needs_reghost = %d", sbi->needs_reghost);
  83
  84         return autofs4_dcache_readdir(file, dirent, filldir);
  85 }
  86
  87 /* Update usage from here to top of tree, so that scan of
  88    top-level directories will give a useful result */
  89 static void autofs4_update_usage(struct dentry *dentry)
  90 {
  91         struct dentry *top = dentry->d_sb->s_root;
  92
  93         spin_lock(&dcache_lock);
  94         for(; dentry != top; dentry = dentry->d_parent) {
  95                 struct autofs_info *ino = autofs4_dentry_ino(dentry);
  96
  97                 if (ino) {
  98                         update_atime(dentry->d_inode);
  99                         ino->last_used = jiffies;
 100                 }
 101         }
 102         spin_unlock(&dcache_lock);
 103 }
 104
 105 /*
 106  * From 2.4 kernel readdir.c
 107  */
 108 static int autofs4_dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
 109 {
 110         int i;
 111         struct dentry *dentry = filp->f_dentry;
 112
 113         i = filp->f_pos;
 114         switch (i) {
 115                 case 0:
 116                         if (filldir(dirent, ".", 1, i, dentry->d_inode->i_ino, DT_DIR) < 0)
 117                                 break;
 118                         i++;
 119                         filp->f_pos++;
 120                         /* fallthrough */
 121                 case 1:
 122                         if (filldir(dirent, "..", 2, i, dentry->d_parent->d_inode->i_ino, DT_DIR) < 0)
 123                                 break;
 124                         i++;
 125                         filp->f_pos++;
 126                         /* fallthrough */
 127                 default: {
 128                         struct list_head *list;
 129                         int j = i-2;
 130
 131                         spin_lock(&dcache_lock);
 132                         list = dentry->d_subdirs.next;
 133
 134                         for (;;) {
 135                                 if (list == &dentry->d_subdirs) {
 136                                         spin_unlock(&dcache_lock);
 137                                         return 0;
 138                                 }
 139                                 if (!j)
 140                                         break;
 141                                 j--;
 142                                 list = list->next;
 143                         }
 144
 145                         while(1) {
 146                                 struct dentry *de = list_entry(list, struct dentry, d_child);
 147
 148                                 if (!d_unhashed(de) && de->d_inode) {
 149                                         spin_unlock(&dcache_lock);
 150                                         if (filldir(dirent, de->d_name.name, de->d_name.len, filp->f_pos, de->d_inode->i_ino, DT_UNKNOWN) < 0)
 151                                                 break;
 152                                         spin_lock(&dcache_lock);
 153                                 }
 154                                 filp->f_pos++;
 155                                 list = list->next;
 156                                 if (list != &dentry->d_subdirs)
 157                                         continue;
 158                                 spin_unlock(&dcache_lock);
 159                                 break;
 160                         }
 161                 }
 162         }
 163         return 0;
 164 }
 165
 166 static int autofs4_dir_open(struct inode *inode, struct file *file)
 167 {
 168         struct dentry *dentry = file->f_dentry;
 169         struct vfsmount *mnt = file->f_vfsmnt;
 170         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 171         int status;
 172
 173         DPRINTK("file=%p dentry=%p %.*s",
 174                 file, dentry, dentry->d_name.len, dentry->d_name.name);
 175
 176         if (autofs4_oz_mode(sbi))
 177                 goto out;
 178
 179         if (autofs4_ispending(dentry)) {
 180                 DPRINTK("dentry busy");
 181                 return -EBUSY;
 182         }
 183
 184         if (!d_mountpoint(dentry) && dentry->d_op && dentry->d_op->d_revalidate) {
 185                 struct nameidata nd;
 186                 int empty;
 187
 188                 /* In case there are stale directory dentrys from a failed mount */
 189                 spin_lock(&dcache_lock);
 190                 empty = list_empty(&dentry->d_subdirs);
 191                 spin_unlock(&dcache_lock);
 192
 193                 if (!empty)
 194                         d_invalidate(dentry);
 195
 196                 nd.flags = LOOKUP_DIRECTORY;
 197                 status = (dentry->d_op->d_revalidate)(dentry, &nd);
 198
 199                 if (!status)
 200                         return -ENOENT;
 201         }
 202
 203         if (d_mountpoint(dentry)) {
 204                 struct file *fp = NULL;
 205                 struct vfsmount *fp_mnt = mntget(mnt);
 206                 struct dentry *fp_dentry = dget(dentry);
 207
 208                 while (follow_down(&fp_mnt, &fp_dentry) && d_mountpoint(fp_dentry));
 209
 210                 fp = dentry_open(fp_dentry, fp_mnt, file->f_flags);
 211                 status = PTR_ERR(fp);
 212                 if (IS_ERR(fp)) {
 213                         file->private_data = NULL;
 214                         return status;
 215                 }
 216                 file->private_data = fp;
 217         }
 218 out:
 219         return 0;
 220 }
 221
 222 static int autofs4_dir_close(struct inode *inode, struct file *file)
 223 {
 224         struct dentry *dentry = file->f_dentry;
 225         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 226
 227         DPRINTK("file=%p dentry=%p %.*s",
 228                 file, dentry, dentry->d_name.len, dentry->d_name.name);
 229
 230         if (autofs4_oz_mode(sbi))
 231                 goto out;
 232
 233         if (autofs4_ispending(dentry)) {
 234                 DPRINTK("dentry busy");
 235                 return -EBUSY;
 236         }
 237
 238         if (d_mountpoint(dentry)) {
 239                 struct file *fp = file->private_data;
 240
 241                 if (!fp)
 242                         return -ENOENT;
 243
 244                 filp_close(fp, current->files);
 245                 file->private_data = NULL;
 246         }
 247 out:
 248         return 0;
 249 }
 250
 251 static int autofs4_dir_readdir(struct file *file, void *dirent, filldir_t filldir)
 252 {
 253         struct dentry *dentry = file->f_dentry;
 254         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 255         int status;
 256
 257         DPRINTK("file=%p dentry=%p %.*s",
 258                 file, dentry, dentry->d_name.len, dentry->d_name.name);
 259
 260         if (autofs4_oz_mode(sbi))
 261                 goto out;
 262
 263         if (autofs4_ispending(dentry)) {
 264                 DPRINTK("dentry busy");
 265                 return -EBUSY;
 266         }
 267
 268         if (d_mountpoint(dentry)) {
 269                 struct file *fp = file->private_data;
 270
 271                 if (!fp)
 272                         return -ENOENT;
 273
 274                 if (!fp->f_op || !fp->f_op->readdir)
 275                         goto out;
 276
 277                 status = vfs_readdir(fp, filldir, dirent);
 278                 file->f_pos = fp->f_pos;
 279                 if (status)
 280                         autofs4_copy_atime(file, fp);
 281                 return status;
 282         }
 283 out:
 284         return autofs4_dcache_readdir(file, dirent, filldir);
 285 }
 286
 287 static int try_to_fill_dentry(struct dentry *dentry,
 288                               struct super_block *sb,
 289                               struct autofs_sb_info *sbi, int flags)
 290 {
 291         struct autofs_info *de_info = autofs4_dentry_ino(dentry);
 292         int status = 0;
 293
 294         /* Block on any pending expiry here; invalidate the dentry
 295            when expiration is done to trigger mount request with a new
 296            dentry */
 297         if (de_info && (de_info->flags & AUTOFS_INF_EXPIRING)) {
 298                 DPRINTK("waiting for expire %p name=%.*s",
 299                          dentry, dentry->d_name.len, dentry->d_name.name);
 300
 301                 status = autofs4_wait(sbi, dentry, NFY_NONE);
 302
 303                 DPRINTK("expire done status=%d", status);
 304
 305                 return 0;
 306         }
 307
 308         DPRINTK("dentry=%p %.*s ino=%p",
 309                  dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode);
 310
 311         /* Wait for a pending mount, triggering one if there isn't one already */
 312         if (dentry->d_inode == NULL) {
 313                 DPRINTK("waiting for mount name=%.*s",
 314                          dentry->d_name.len, dentry->d_name.name);
 315
 316                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 317
 318                 DPRINTK("mount done status=%d", status);
 319
 320                 if (status && dentry->d_inode)
 321                         return 0; /* Try to get the kernel to invalidate this dentry */
 322
 323                 /* Turn this into a real negative dentry? */
 324                 if (status == -ENOENT) {
 325                         dentry->d_time = jiffies + AUTOFS_NEGATIVE_TIMEOUT;
 326                         spin_lock(&dentry->d_lock);
 327                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 328                         spin_unlock(&dentry->d_lock);
 329                         return 1;
 330                 } else if (status) {
 331                         /* Return a negative dentry, but leave it "pending" */
 332                         return 1;
 333                 }
 334         /* Trigger mount for path component or follow link */
 335         } else if (flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY) ||
 336                         current->link_count) {
 337                 DPRINTK("waiting for mount name=%.*s",
 338                         dentry->d_name.len, dentry->d_name.name);
 339
 340                 spin_lock(&dentry->d_lock);
 341                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 342                 spin_unlock(&dentry->d_lock);
 343                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 344
 345                 DPRINTK("mount done status=%d", status);
 346
 347                 if (status) {
 348                         spin_lock(&dentry->d_lock);
 349                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 350                         spin_unlock(&dentry->d_lock);
 351                         return 0;
 352                 }
 353         }
 354
 355         /* We don't update the usages for the autofs daemon itself, this
 356            is necessary for recursive autofs mounts */
 357         if (!autofs4_oz_mode(sbi))
 358                 autofs4_update_usage(dentry);
 359
 360         spin_lock(&dentry->d_lock);
 361         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 362         spin_unlock(&dentry->d_lock);
 363         return 1;
 364 }
 365
 366 /*
 367  * Revalidate is called on every cache lookup.  Some of those
 368  * cache lookups may actually happen while the dentry is not
 369  * yet completely filled in, and revalidate has to delay such
 370  * lookups..
 371  */
 372 static int autofs4_revalidate(struct dentry * dentry, struct nameidata *nd)
 373 {
 374         struct inode * dir = dentry->d_parent->d_inode;
 375         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 376         int oz_mode = autofs4_oz_mode(sbi);
 377         int flags = nd ? nd->flags : 0;
 378         int status = 1;
 379
 380         /* Pending dentry */
 381         if (autofs4_ispending(dentry)) {
 382                 if (!oz_mode)
 383                         status = try_to_fill_dentry(dentry, dir->i_sb, sbi, flags);
 384                 return status;
 385         }
 386
 387         /* Negative dentry.. invalidate if "old" */
 388         if (dentry->d_inode == NULL)
 389                 return (dentry->d_time - jiffies <= AUTOFS_NEGATIVE_TIMEOUT);
 390
 391         /* Check for a non-mountpoint directory with no contents */
 392         spin_lock(&dcache_lock);
 393         if (S_ISDIR(dentry->d_inode->i_mode) &&
 394             !d_mountpoint(dentry) &&
 395             list_empty(&dentry->d_subdirs)) {
 396                 DPRINTK("dentry=%p %.*s, emptydir",
 397                          dentry, dentry->d_name.len, dentry->d_name.name);
 398                 spin_unlock(&dcache_lock);
 399                 if (!oz_mode)
 400                         status = try_to_fill_dentry(dentry, dir->i_sb, sbi, flags);
 401                 return status;
 402         }
 403         spin_unlock(&dcache_lock);
 404
 405         /* Update the usage list */
 406         if (!oz_mode)
 407                 autofs4_update_usage(dentry);
 408
 409         return 1;
 410 }
 411
 412 static void autofs4_dentry_release(struct dentry *de)
 413 {
 414         struct autofs_info *inf;
 415
 416         DPRINTK("releasing %p", de);
 417
 418         inf = autofs4_dentry_ino(de);
 419         de->d_fsdata = NULL;
 420
 421         if (inf) {
 422                 inf->dentry = NULL;
 423                 inf->inode = NULL;
 424
 425                 autofs4_free_ino(inf);
 426         }
 427 }
 428
 429 /* For dentries of directories in the root dir */
 430 static struct dentry_operations autofs4_root_dentry_operations = {
 431         .d_revalidate   = autofs4_revalidate,
 432         .d_release      = autofs4_dentry_release,
 433 };
 434
 435 /* For other dentries */
 436 static struct dentry_operations autofs4_dentry_operations = {
 437         .d_revalidate   = autofs4_revalidate,
 438         .d_release      = autofs4_dentry_release,
 439 };
 440
 441 /* Lookups in the root directory */
 442 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 443 {
 444         struct autofs_sb_info *sbi;
 445         int oz_mode;
 446
 447         DPRINTK("name = %.*s",
 448                 dentry->d_name.len, dentry->d_name.name);
 449
 450         if (dentry->d_name.len > NAME_MAX)
 451                 return ERR_PTR(-ENAMETOOLONG);/* File name too long to exist */
 452
 453         sbi = autofs4_sbi(dir->i_sb);
 454
 455         oz_mode = autofs4_oz_mode(sbi);
 456         DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
 457                  current->pid, process_group(current), sbi->catatonic, oz_mode);
 458
 459         /*
 460          * Mark the dentry incomplete, but add it. This is needed so
 461          * that the VFS layer knows about the dentry, and we can count
 462          * on catching any lookups through the revalidate.
 463          *
 464          * Let all the hard work be done by the revalidate function that
 465          * needs to be able to do this anyway..
 466          *
 467          * We need to do this before we release the directory semaphore.
 468          */
 469         dentry->d_op = &autofs4_root_dentry_operations;
 470
 471         if (!oz_mode) {
 472                 spin_lock(&dentry->d_lock);
 473                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 474                 spin_unlock(&dentry->d_lock);
 475         }
 476         dentry->d_fsdata = NULL;
 477         d_add(dentry, NULL);
 478
 479         if (dentry->d_op && dentry->d_op->d_revalidate) {
 480                 up(&dir->i_sem);
 481                 (dentry->d_op->d_revalidate)(dentry, nd);
 482                 down(&dir->i_sem);
 483         }
 484
 485         /*
 486          * If we are still pending, check if we had to handle
 487          * a signal. If so we can force a restart..
 488          */
 489         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 490                 /* See if we were interrupted */
 491                 if (signal_pending(current)) {
 492                         sigset_t *sigset = &current->pending.signal;
 493                         if (sigismember (sigset, SIGKILL) ||
 494                             sigismember (sigset, SIGQUIT) ||
 495                             sigismember (sigset, SIGINT)) {
 496                             return ERR_PTR(-ERESTARTNOINTR);
 497                         }
 498                 }
 499         }
 500
 501         /*
 502          * If this dentry is unhashed, then we shouldn't honour this
 503          * lookup even if the dentry is positive.  Returning ENOENT here
 504          * doesn't do the right thing for all system calls, but it should
 505          * be OK for the operations we permit from an autofs.
 506          */
 507         if ( dentry->d_inode && d_unhashed(dentry) )
 508                 return ERR_PTR(-ENOENT);
 509
 510         return NULL;
 511 }
 512
 513 static int autofs4_dir_symlink(struct inode *dir,
 514                                struct dentry *dentry,
 515                                const char *symname)
 516 {
 517         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 518         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 519         struct inode *inode;
 520         char *cp;
 521
 522         DPRINTK("%s <- %.*s", symname,
 523                 dentry->d_name.len, dentry->d_name.name);
 524
 525         if (!autofs4_oz_mode(sbi))
 526                 return -EACCES;
 527
 528         ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
 529         if (ino == NULL)
 530                 return -ENOSPC;
 531
 532         ino->size = strlen(symname);
 533         ino->u.symlink = cp = kmalloc(ino->size + 1, GFP_KERNEL);
 534
 535         if (cp == NULL) {
 536                 kfree(ino);
 537                 return -ENOSPC;
 538         }
 539
 540         strcpy(cp, symname);
 541
 542         inode = autofs4_get_inode(dir->i_sb, ino);
 543         d_instantiate(dentry, inode);
 544
 545         if (dir == dir->i_sb->s_root->d_inode)
 546                 dentry->d_op = &autofs4_root_dentry_operations;
 547         else
 548                 dentry->d_op = &autofs4_dentry_operations;
 549
 550         dentry->d_fsdata = ino;
 551         ino->dentry = dget(dentry);
 552         ino->inode = inode;
 553
 554         dir->i_mtime = CURRENT_TIME;
 555
 556         return 0;
 557 }
 558
 559 /*
 560  * NOTE!
 561  *
 562  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 563  * that the file no longer exists. However, doing that means that the
 564  * VFS layer can turn the dentry into a negative dentry.  We don't want
 565  * this, because since the unlink is probably the result of an expire.
 566  * We simply d_drop it, which allows the dentry lookup to remount it
 567  * if necessary.
 568  *
 569  * If a process is blocked on the dentry waiting for the expire to finish,
 570  * it will invalidate the dentry and try to mount with a new one.
 571  *
 572  * Also see autofs4_dir_rmdir()..
 573  */
 574 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
 575 {
 576         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 577         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 578
 579         /* This allows root to remove symlinks */
 580         if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
 581                 return -EACCES;
 582
 583         dput(ino->dentry);
 584
 585         dentry->d_inode->i_size = 0;
 586         dentry->d_inode->i_nlink = 0;
 587
 588         dir->i_mtime = CURRENT_TIME;
 589
 590         d_drop(dentry);
 591
 592         return 0;
 593 }
 594
 595 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
 596 {
 597         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 598         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 599
 600         if (!autofs4_oz_mode(sbi))
 601                 return -EACCES;
 602
 603         spin_lock(&dcache_lock);
 604         if (!list_empty(&dentry->d_subdirs)) {
 605                 spin_unlock(&dcache_lock);
 606                 return -ENOTEMPTY;
 607         }
 608         spin_lock(&dentry->d_lock);
 609         __d_drop(dentry);
 610         spin_unlock(&dentry->d_lock);
 611         spin_unlock(&dcache_lock);
 612
 613         dput(ino->dentry);
 614
 615         dentry->d_inode->i_size = 0;
 616         dentry->d_inode->i_nlink = 0;
 617
 618         if (dir->i_nlink)
 619                 dir->i_nlink--;
 620
 621         return 0;
 622 }
 623
 624 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 625 {
 626         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 627         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 628         struct inode *inode;
 629
 630         if ( !autofs4_oz_mode(sbi) )
 631                 return -EACCES;
 632
 633         DPRINTK("dentry %p, creating %.*s",
 634                 dentry, dentry->d_name.len, dentry->d_name.name);
 635
 636         ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
 637         if (ino == NULL)
 638                 return -ENOSPC;
 639
 640         inode = autofs4_get_inode(dir->i_sb, ino);
 641         d_instantiate(dentry, inode);
 642
 643         if (dir == dir->i_sb->s_root->d_inode)
 644                 dentry->d_op = &autofs4_root_dentry_operations;
 645         else
 646                 dentry->d_op = &autofs4_dentry_operations;
 647
 648         dentry->d_fsdata = ino;
 649         ino->dentry = dget(dentry);
 650         ino->inode = inode;
 651         dir->i_nlink++;
 652         dir->i_mtime = CURRENT_TIME;
 653
 654         return 0;
 655 }
 656
 657 /* Get/set timeout ioctl() operation */
 658 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
 659                                          unsigned long __user *p)
 660 {
 661         int rv;
 662         unsigned long ntimeout;
 663
 664         if ( (rv = get_user(ntimeout, p)) ||
 665              (rv = put_user(sbi->exp_timeout/HZ, p)) )
 666                 return rv;
 667
 668         if ( ntimeout > ULONG_MAX/HZ )
 669                 sbi->exp_timeout = 0;
 670         else
 671                 sbi->exp_timeout = ntimeout * HZ;
 672
 673         return 0;
 674 }
 675
 676 /* Return protocol version */
 677 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
 678 {
 679         return put_user(sbi->version, p);
 680 }
 681
 682 /* Return protocol sub version */
 683 static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
 684 {
 685         return put_user(sbi->sub_version, p);
 686 }
 687
 688 /*
 689  * Tells the daemon whether we need to reghost or not. Also, clears
 690  * the reghost_needed flag.
 691  */
 692 static inline int autofs4_ask_reghost(struct autofs_sb_info *sbi, int __user *p)
 693 {
 694         int status;
 695
 696         DPRINTK("returning %d", sbi->needs_reghost);
 697
 698         status = put_user(sbi->needs_reghost, p);
 699         if ( status )
 700                 return status;
 701
 702         sbi->needs_reghost = 0;
 703         return 0;
 704 }
 705
 706 /*
 707  * Enable / Disable reghosting ioctl() operation
 708  */
 709 static inline int autofs4_toggle_reghost(struct autofs_sb_info *sbi, int __user *p)
 710 {
 711         int status;
 712         int val;
 713
 714         status = get_user(val, p);
 715
 716         DPRINTK("reghost = %d", val);
 717
 718         if (status)
 719                 return status;
 720
 721         /* turn on/off reghosting, with the val */
 722         sbi->reghost_enabled = val;
 723         return 0;
 724 }
 725
 726 /*
 727 * Tells the daemon whether it can umount the autofs mount.
 728 */
 729 static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
 730 {
 731         int status = 0;
 732
 733         if (may_umount(mnt) == 0)
 734                 status = 1;
 735
 736         DPRINTK("returning %d", status);
 737
 738         status = put_user(status, p);
 739
 740         return status;
 741 }
 742
 743 /* Identify autofs4_dentries - this is so we can tell if there's
 744    an extra dentry refcount or not.  We only hold a refcount on the
 745    dentry if its non-negative (ie, d_inode != NULL)
 746 */
 747 int is_autofs4_dentry(struct dentry *dentry)
 748 {
 749         return dentry && dentry->d_inode &&
 750                 (dentry->d_op == &autofs4_root_dentry_operations ||
 751                  dentry->d_op == &autofs4_dentry_operations) &&
 752                 dentry->d_fsdata != NULL;
 753 }
 754
 755 /*
 756  * ioctl()'s on the root directory is the chief method for the daemon to
 757  * generate kernel reactions
 758  */
 759 static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
 760                              unsigned int cmd, unsigned long arg)
 761 {
 762         struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
 763         void __user *p = (void __user *)arg;
 764
 765         DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
 766                 cmd,arg,sbi,process_group(current));
 767
 768         if ( _IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
 769              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT )
 770                 return -ENOTTY;
 771
 772         if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
 773                 return -EPERM;
 774
 775         switch(cmd) {
 776         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
 777                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
 778         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
 779                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
 780         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
 781                 autofs4_catatonic_mode(sbi);
 782                 return 0;
 783         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
 784                 return autofs4_get_protover(sbi, p);
 785         case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
 786                 return autofs4_get_protosubver(sbi, p);
 787         case AUTOFS_IOC_SETTIMEOUT:
 788                 return autofs4_get_set_timeout(sbi, p);
 789
 790         case AUTOFS_IOC_TOGGLEREGHOST:
 791                 return autofs4_toggle_reghost(sbi, p);
 792         case AUTOFS_IOC_ASKREGHOST:
 793                 return autofs4_ask_reghost(sbi, p);
 794
 795         case AUTOFS_IOC_ASKUMOUNT:
 796                 return autofs4_ask_umount(filp->f_vfsmnt, p);
 797
 798         /* return a single thing to expire */
 799         case AUTOFS_IOC_EXPIRE:
 800                 return autofs4_expire_run(inode->i_sb,filp->f_vfsmnt,sbi, p);
 801         /* same as above, but can send multiple expires through pipe */
 802         case AUTOFS_IOC_EXPIRE_MULTI:
 803                 return autofs4_expire_multi(inode->i_sb,filp->f_vfsmnt,sbi, p);
 804
 805         default:
 806                 return -ENOSYS;
 807         }
 808 }