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/capability.h>
  16 #include <linux/errno.h>
  17 #include <linux/stat.h>
  18 #include <linux/param.h>
  19 #include <linux/time.h>
  20 #include <linux/smp_lock.h>
  21 #include "autofs_i.h"
  22
  23 static int autofs4_dir_symlink(struct inode *,struct dentry *,const char *);
  24 static int autofs4_dir_unlink(struct inode *,struct dentry *);
  25 static int autofs4_dir_rmdir(struct inode *,struct dentry *);
  26 static int autofs4_dir_mkdir(struct inode *,struct dentry *,int);
  27 static int autofs4_root_ioctl(struct inode *, struct file *,unsigned int,unsigned long);
  28 static int autofs4_dir_open(struct inode *inode, struct file *file);
  29 static int autofs4_dir_close(struct inode *inode, struct file *file);
  30 static int autofs4_dir_readdir(struct file * filp, void * dirent, filldir_t filldir);
  31 static int autofs4_root_readdir(struct file * filp, void * dirent, filldir_t filldir);
  32 static struct dentry *autofs4_lookup(struct inode *,struct dentry *, struct nameidata *);
  33 static int autofs4_dcache_readdir(struct file *, void *, filldir_t);
  34
  35 struct file_operations autofs4_root_operations = {
  36         .open           = dcache_dir_open,
  37         .release        = dcache_dir_close,
  38         .read           = generic_read_dir,
  39         .readdir        = autofs4_root_readdir,
  40         .ioctl          = autofs4_root_ioctl,
  41 };
  42
  43 struct file_operations autofs4_dir_operations = {
  44         .open           = autofs4_dir_open,
  45         .release        = autofs4_dir_close,
  46         .read           = generic_read_dir,
  47         .readdir        = autofs4_dir_readdir,
  48 };
  49
  50 struct inode_operations autofs4_root_inode_operations = {
  51         .lookup         = autofs4_lookup,
  52         .unlink         = autofs4_dir_unlink,
  53         .symlink        = autofs4_dir_symlink,
  54         .mkdir          = autofs4_dir_mkdir,
  55         .rmdir          = autofs4_dir_rmdir,
  56 };
  57
  58 struct inode_operations autofs4_dir_inode_operations = {
  59         .lookup         = autofs4_lookup,
  60         .unlink         = autofs4_dir_unlink,
  61         .symlink        = autofs4_dir_symlink,
  62         .mkdir          = autofs4_dir_mkdir,
  63         .rmdir          = autofs4_dir_rmdir,
  64 };
  65
  66 static int autofs4_root_readdir(struct file *file, void *dirent,
  67                                 filldir_t filldir)
  68 {
  69         struct autofs_sb_info *sbi = autofs4_sbi(file->f_dentry->d_sb);
  70         int oz_mode = autofs4_oz_mode(sbi);
  71
  72         DPRINTK("called, filp->f_pos = %lld", file->f_pos);
  73
  74         /*
  75          * Don't set reghost flag if:
  76          * 1) f_pos is larger than zero -- we've already been here.
  77          * 2) we haven't even enabled reghosting in the 1st place.
  78          * 3) this is the daemon doing a readdir
  79          */
  80         if (oz_mode && file->f_pos == 0 && sbi->reghost_enabled)
  81                 sbi->needs_reghost = 1;
  82
  83         DPRINTK("needs_reghost = %d", sbi->needs_reghost);
  84
  85         return autofs4_dcache_readdir(file, dirent, filldir);
  86 }
  87
  88 /* Update usage from here to top of tree, so that scan of
  89    top-level directories will give a useful result */
  90 static void autofs4_update_usage(struct vfsmount *mnt, struct dentry *dentry)
  91 {
  92         struct dentry *top = dentry->d_sb->s_root;
  93
  94         spin_lock(&dcache_lock);
  95         for(; dentry != top; dentry = dentry->d_parent) {
  96                 struct autofs_info *ino = autofs4_dentry_ino(dentry);
  97
  98                 if (ino) {
  99                         touch_atime(mnt, dentry);
 100                         ino->last_used = jiffies;
 101                 }
 102         }
 103         spin_unlock(&dcache_lock);
 104 }
 105
 106 /*
 107  * From 2.4 kernel readdir.c
 108  */
 109 static int autofs4_dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
 110 {
 111         int i;
 112         struct dentry *dentry = filp->f_dentry;
 113
 114         i = filp->f_pos;
 115         switch (i) {
 116                 case 0:
 117                         if (filldir(dirent, ".", 1, i, dentry->d_inode->i_ino, DT_DIR) < 0)
 118                                 break;
 119                         i++;
 120                         filp->f_pos++;
 121                         /* fallthrough */
 122                 case 1:
 123                         if (filldir(dirent, "..", 2, i, dentry->d_parent->d_inode->i_ino, DT_DIR) < 0)
 124                                 break;
 125                         i++;
 126                         filp->f_pos++;
 127                         /* fallthrough */
 128                 default: {
 129                         struct list_head *list;
 130                         int j = i-2;
 131
 132                         spin_lock(&dcache_lock);
 133                         list = dentry->d_subdirs.next;
 134
 135                         for (;;) {
 136                                 if (list == &dentry->d_subdirs) {
 137                                         spin_unlock(&dcache_lock);
 138                                         return 0;
 139                                 }
 140                                 if (!j)
 141                                         break;
 142                                 j--;
 143                                 list = list->next;
 144                         }
 145
 146                         while(1) {
 147                                 struct dentry *de = list_entry(list,
 148                                                 struct dentry, d_u.d_child);
 149
 150                                 if (!d_unhashed(de) && de->d_inode) {
 151                                         spin_unlock(&dcache_lock);
 152                                         if (filldir(dirent, de->d_name.name, de->d_name.len, filp->f_pos, de->d_inode->i_ino, DT_UNKNOWN) < 0)
 153                                                 break;
 154                                         spin_lock(&dcache_lock);
 155                                 }
 156                                 filp->f_pos++;
 157                                 list = list->next;
 158                                 if (list != &dentry->d_subdirs)
 159                                         continue;
 160                                 spin_unlock(&dcache_lock);
 161                                 break;
 162                         }
 163                 }
 164         }
 165         return 0;
 166 }
 167
 168 static int autofs4_dir_open(struct inode *inode, struct file *file)
 169 {
 170         struct dentry *dentry = file->f_dentry;
 171         struct vfsmount *mnt = file->f_vfsmnt;
 172         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 173         int status;
 174
 175         DPRINTK("file=%p dentry=%p %.*s",
 176                 file, dentry, dentry->d_name.len, dentry->d_name.name);
 177
 178         if (autofs4_oz_mode(sbi))
 179                 goto out;
 180
 181         if (autofs4_ispending(dentry)) {
 182                 DPRINTK("dentry busy");
 183                 return -EBUSY;
 184         }
 185
 186         if (!d_mountpoint(dentry) && dentry->d_op && dentry->d_op->d_revalidate) {
 187                 struct nameidata nd;
 188                 int empty;
 189
 190                 /* In case there are stale directory dentrys from a failed mount */
 191                 spin_lock(&dcache_lock);
 192                 empty = list_empty(&dentry->d_subdirs);
 193                 spin_unlock(&dcache_lock);
 194
 195                 if (!empty)
 196                         d_invalidate(dentry);
 197
 198                 nd.dentry = dentry;
 199                 nd.mnt = mnt;
 200                 nd.flags = LOOKUP_DIRECTORY;
 201                 status = (dentry->d_op->d_revalidate)(dentry, &nd);
 202
 203                 if (!status)
 204                         return -ENOENT;
 205         }
 206
 207         if (d_mountpoint(dentry)) {
 208                 struct file *fp = NULL;
 209                 struct vfsmount *fp_mnt = mntget(mnt);
 210                 struct dentry *fp_dentry = dget(dentry);
 211
 212                 if (!autofs4_follow_mount(&fp_mnt, &fp_dentry)) {
 213                         dput(fp_dentry);
 214                         mntput(fp_mnt);
 215                         return -ENOENT;
 216                 }
 217
 218                 fp = dentry_open(fp_dentry, fp_mnt, file->f_flags);
 219                 status = PTR_ERR(fp);
 220                 if (IS_ERR(fp)) {
 221                         file->private_data = NULL;
 222                         return status;
 223                 }
 224                 file->private_data = fp;
 225         }
 226 out:
 227         return 0;
 228 }
 229
 230 static int autofs4_dir_close(struct inode *inode, struct file *file)
 231 {
 232         struct dentry *dentry = file->f_dentry;
 233         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 234
 235         DPRINTK("file=%p dentry=%p %.*s",
 236                 file, dentry, dentry->d_name.len, dentry->d_name.name);
 237
 238         if (autofs4_oz_mode(sbi))
 239                 goto out;
 240
 241         if (autofs4_ispending(dentry)) {
 242                 DPRINTK("dentry busy");
 243                 return -EBUSY;
 244         }
 245
 246         if (d_mountpoint(dentry)) {
 247                 struct file *fp = file->private_data;
 248
 249                 if (!fp)
 250                         return -ENOENT;
 251
 252                 filp_close(fp, current->files);
 253                 file->private_data = NULL;
 254         }
 255 out:
 256         return 0;
 257 }
 258
 259 static int autofs4_dir_readdir(struct file *file, void *dirent, filldir_t filldir)
 260 {
 261         struct dentry *dentry = file->f_dentry;
 262         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 263         int status;
 264
 265         DPRINTK("file=%p dentry=%p %.*s",
 266                 file, dentry, dentry->d_name.len, dentry->d_name.name);
 267
 268         if (autofs4_oz_mode(sbi))
 269                 goto out;
 270
 271         if (autofs4_ispending(dentry)) {
 272                 DPRINTK("dentry busy");
 273                 return -EBUSY;
 274         }
 275
 276         if (d_mountpoint(dentry)) {
 277                 struct file *fp = file->private_data;
 278
 279                 if (!fp)
 280                         return -ENOENT;
 281
 282                 if (!fp->f_op || !fp->f_op->readdir)
 283                         goto out;
 284
 285                 status = vfs_readdir(fp, filldir, dirent);
 286                 file->f_pos = fp->f_pos;
 287                 if (status)
 288                         autofs4_copy_atime(file, fp);
 289                 return status;
 290         }
 291 out:
 292         return autofs4_dcache_readdir(file, dirent, filldir);
 293 }
 294
 295 static int try_to_fill_dentry(struct vfsmount *mnt, struct dentry *dentry, int flags)
 296 {
 297         struct super_block *sb = mnt->mnt_sb;
 298         struct autofs_sb_info *sbi = autofs4_sbi(sb);
 299         struct autofs_info *de_info = autofs4_dentry_ino(dentry);
 300         int status = 0;
 301
 302         /* Block on any pending expiry here; invalidate the dentry
 303            when expiration is done to trigger mount request with a new
 304            dentry */
 305         if (de_info && (de_info->flags & AUTOFS_INF_EXPIRING)) {
 306                 DPRINTK("waiting for expire %p name=%.*s",
 307                          dentry, dentry->d_name.len, dentry->d_name.name);
 308
 309                 status = autofs4_wait(sbi, dentry, NFY_NONE);
 310
 311                 DPRINTK("expire done status=%d", status);
 312
 313                 /*
 314                  * If the directory still exists the mount request must
 315                  * continue otherwise it can't be followed at the right
 316                  * time during the walk.
 317                  */
 318                 status = d_invalidate(dentry);
 319                 if (status != -EBUSY)
 320                         return 0;
 321         }
 322
 323         DPRINTK("dentry=%p %.*s ino=%p",
 324                  dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode);
 325
 326         /* Wait for a pending mount, triggering one if there isn't one already */
 327         if (dentry->d_inode == NULL) {
 328                 DPRINTK("waiting for mount name=%.*s",
 329                          dentry->d_name.len, dentry->d_name.name);
 330
 331                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 332
 333                 DPRINTK("mount done status=%d", status);
 334
 335                 if (status && dentry->d_inode)
 336                         return 0; /* Try to get the kernel to invalidate this dentry */
 337
 338                 /* Turn this into a real negative dentry? */
 339                 if (status == -ENOENT) {
 340                         dentry->d_time = jiffies + AUTOFS_NEGATIVE_TIMEOUT;
 341                         spin_lock(&dentry->d_lock);
 342                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 343                         spin_unlock(&dentry->d_lock);
 344                         return 1;
 345                 } else if (status) {
 346                         /* Return a negative dentry, but leave it "pending" */
 347                         return 1;
 348                 }
 349         /* Trigger mount for path component or follow link */
 350         } else if (flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY) ||
 351                         current->link_count) {
 352                 DPRINTK("waiting for mount name=%.*s",
 353                         dentry->d_name.len, dentry->d_name.name);
 354
 355                 spin_lock(&dentry->d_lock);
 356                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 357                 spin_unlock(&dentry->d_lock);
 358                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 359
 360                 DPRINTK("mount done status=%d", status);
 361
 362                 if (status) {
 363                         spin_lock(&dentry->d_lock);
 364                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 365                         spin_unlock(&dentry->d_lock);
 366                         return 0;
 367                 }
 368         }
 369
 370         /* We don't update the usages for the autofs daemon itself, this
 371            is necessary for recursive autofs mounts */
 372         if (!autofs4_oz_mode(sbi))
 373                 autofs4_update_usage(mnt, dentry);
 374
 375         spin_lock(&dentry->d_lock);
 376         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 377         spin_unlock(&dentry->d_lock);
 378         return 1;
 379 }
 380
 381 /*
 382  * Revalidate is called on every cache lookup.  Some of those
 383  * cache lookups may actually happen while the dentry is not
 384  * yet completely filled in, and revalidate has to delay such
 385  * lookups..
 386  */
 387 static int autofs4_revalidate(struct dentry * dentry, struct nameidata *nd)
 388 {
 389         struct inode * dir = dentry->d_parent->d_inode;
 390         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 391         int oz_mode = autofs4_oz_mode(sbi);
 392         int flags = nd ? nd->flags : 0;
 393         int status = 1;
 394
 395         /* Pending dentry */
 396         if (autofs4_ispending(dentry)) {
 397                 if (!oz_mode)
 398                         status = try_to_fill_dentry(nd->mnt, dentry, flags);
 399                 return status;
 400         }
 401
 402         /* Negative dentry.. invalidate if "old" */
 403         if (dentry->d_inode == NULL)
 404                 return (dentry->d_time - jiffies <= AUTOFS_NEGATIVE_TIMEOUT);
 405
 406         /* Check for a non-mountpoint directory with no contents */
 407         spin_lock(&dcache_lock);
 408         if (S_ISDIR(dentry->d_inode->i_mode) &&
 409             !d_mountpoint(dentry) &&
 410             list_empty(&dentry->d_subdirs)) {
 411                 DPRINTK("dentry=%p %.*s, emptydir",
 412                          dentry, dentry->d_name.len, dentry->d_name.name);
 413                 spin_unlock(&dcache_lock);
 414                 if (!oz_mode)
 415                         status = try_to_fill_dentry(nd->mnt, dentry, flags);
 416                 return status;
 417         }
 418         spin_unlock(&dcache_lock);
 419
 420         /* Update the usage list */
 421         if (!oz_mode)
 422                 autofs4_update_usage(nd->mnt, dentry);
 423
 424         return 1;
 425 }
 426
 427 static void autofs4_dentry_release(struct dentry *de)
 428 {
 429         struct autofs_info *inf;
 430
 431         DPRINTK("releasing %p", de);
 432
 433         inf = autofs4_dentry_ino(de);
 434         de->d_fsdata = NULL;
 435
 436         if (inf) {
 437                 inf->dentry = NULL;
 438                 inf->inode = NULL;
 439
 440                 autofs4_free_ino(inf);
 441         }
 442 }
 443
 444 /* For dentries of directories in the root dir */
 445 static struct dentry_operations autofs4_root_dentry_operations = {
 446         .d_revalidate   = autofs4_revalidate,
 447         .d_release      = autofs4_dentry_release,
 448 };
 449
 450 /* For other dentries */
 451 static struct dentry_operations autofs4_dentry_operations = {
 452         .d_revalidate   = autofs4_revalidate,
 453         .d_release      = autofs4_dentry_release,
 454 };
 455
 456 /* Lookups in the root directory */
 457 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 458 {
 459         struct autofs_sb_info *sbi;
 460         int oz_mode;
 461
 462         DPRINTK("name = %.*s",
 463                 dentry->d_name.len, dentry->d_name.name);
 464
 465         if (dentry->d_name.len > NAME_MAX)
 466                 return ERR_PTR(-ENAMETOOLONG);/* File name too long to exist */
 467
 468         sbi = autofs4_sbi(dir->i_sb);
 469
 470         oz_mode = autofs4_oz_mode(sbi);
 471         DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
 472                  current->pid, process_group(current), sbi->catatonic, oz_mode);
 473
 474         /*
 475          * Mark the dentry incomplete, but add it. This is needed so
 476          * that the VFS layer knows about the dentry, and we can count
 477          * on catching any lookups through the revalidate.
 478          *
 479          * Let all the hard work be done by the revalidate function that
 480          * needs to be able to do this anyway..
 481          *
 482          * We need to do this before we release the directory semaphore.
 483          */
 484         dentry->d_op = &autofs4_root_dentry_operations;
 485
 486         if (!oz_mode) {
 487                 spin_lock(&dentry->d_lock);
 488                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 489                 spin_unlock(&dentry->d_lock);
 490         }
 491         dentry->d_fsdata = NULL;
 492         d_add(dentry, NULL);
 493
 494         if (dentry->d_op && dentry->d_op->d_revalidate) {
 495                 mutex_unlock(&dir->i_mutex);
 496                 (dentry->d_op->d_revalidate)(dentry, nd);
 497                 mutex_lock(&dir->i_mutex);
 498         }
 499
 500         /*
 501          * If we are still pending, check if we had to handle
 502          * a signal. If so we can force a restart..
 503          */
 504         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 505                 /* See if we were interrupted */
 506                 if (signal_pending(current)) {
 507                         sigset_t *sigset = &current->pending.signal;
 508                         if (sigismember (sigset, SIGKILL) ||
 509                             sigismember (sigset, SIGQUIT) ||
 510                             sigismember (sigset, SIGINT)) {
 511                             return ERR_PTR(-ERESTARTNOINTR);
 512                         }
 513                 }
 514         }
 515
 516         /*
 517          * If this dentry is unhashed, then we shouldn't honour this
 518          * lookup even if the dentry is positive.  Returning ENOENT here
 519          * doesn't do the right thing for all system calls, but it should
 520          * be OK for the operations we permit from an autofs.
 521          */
 522         if ( dentry->d_inode && d_unhashed(dentry) )
 523                 return ERR_PTR(-ENOENT);
 524
 525         return NULL;
 526 }
 527
 528 static int autofs4_dir_symlink(struct inode *dir,
 529                                struct dentry *dentry,
 530                                const char *symname)
 531 {
 532         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 533         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 534         struct inode *inode;
 535         char *cp;
 536
 537         DPRINTK("%s <- %.*s", symname,
 538                 dentry->d_name.len, dentry->d_name.name);
 539
 540         if (!autofs4_oz_mode(sbi))
 541                 return -EACCES;
 542
 543         ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
 544         if (ino == NULL)
 545                 return -ENOSPC;
 546
 547         ino->size = strlen(symname);
 548         ino->u.symlink = cp = kmalloc(ino->size + 1, GFP_KERNEL);
 549
 550         if (cp == NULL) {
 551                 kfree(ino);
 552                 return -ENOSPC;
 553         }
 554
 555         strcpy(cp, symname);
 556
 557         inode = autofs4_get_inode(dir->i_sb, ino);
 558         d_instantiate(dentry, inode);
 559
 560         if (dir == dir->i_sb->s_root->d_inode)
 561                 dentry->d_op = &autofs4_root_dentry_operations;
 562         else
 563                 dentry->d_op = &autofs4_dentry_operations;
 564
 565         dentry->d_fsdata = ino;
 566         ino->dentry = dget(dentry);
 567         ino->inode = inode;
 568
 569         dir->i_mtime = CURRENT_TIME;
 570
 571         return 0;
 572 }
 573
 574 /*
 575  * NOTE!
 576  *
 577  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 578  * that the file no longer exists. However, doing that means that the
 579  * VFS layer can turn the dentry into a negative dentry.  We don't want
 580  * this, because since the unlink is probably the result of an expire.
 581  * We simply d_drop it, which allows the dentry lookup to remount it
 582  * if necessary.
 583  *
 584  * If a process is blocked on the dentry waiting for the expire to finish,
 585  * it will invalidate the dentry and try to mount with a new one.
 586  *
 587  * Also see autofs4_dir_rmdir()..
 588  */
 589 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
 590 {
 591         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 592         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 593
 594         /* This allows root to remove symlinks */
 595         if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
 596                 return -EACCES;
 597
 598         dput(ino->dentry);
 599
 600         dentry->d_inode->i_size = 0;
 601         dentry->d_inode->i_nlink = 0;
 602
 603         dir->i_mtime = CURRENT_TIME;
 604
 605         d_drop(dentry);
 606
 607         return 0;
 608 }
 609
 610 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
 611 {
 612         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 613         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 614
 615         if (!autofs4_oz_mode(sbi))
 616                 return -EACCES;
 617
 618         spin_lock(&dcache_lock);
 619         if (!list_empty(&dentry->d_subdirs)) {
 620                 spin_unlock(&dcache_lock);
 621                 return -ENOTEMPTY;
 622         }
 623         spin_lock(&dentry->d_lock);
 624         __d_drop(dentry);
 625         spin_unlock(&dentry->d_lock);
 626         spin_unlock(&dcache_lock);
 627
 628         dput(ino->dentry);
 629
 630         dentry->d_inode->i_size = 0;
 631         dentry->d_inode->i_nlink = 0;
 632
 633         if (dir->i_nlink)
 634                 dir->i_nlink--;
 635
 636         return 0;
 637 }
 638
 639 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 640 {
 641         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 642         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 643         struct inode *inode;
 644
 645         if ( !autofs4_oz_mode(sbi) )
 646                 return -EACCES;
 647
 648         DPRINTK("dentry %p, creating %.*s",
 649                 dentry, dentry->d_name.len, dentry->d_name.name);
 650
 651         ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
 652         if (ino == NULL)
 653                 return -ENOSPC;
 654
 655         inode = autofs4_get_inode(dir->i_sb, ino);
 656         d_instantiate(dentry, inode);
 657
 658         if (dir == dir->i_sb->s_root->d_inode)
 659                 dentry->d_op = &autofs4_root_dentry_operations;
 660         else
 661                 dentry->d_op = &autofs4_dentry_operations;
 662
 663         dentry->d_fsdata = ino;
 664         ino->dentry = dget(dentry);
 665         ino->inode = inode;
 666         dir->i_nlink++;
 667         dir->i_mtime = CURRENT_TIME;
 668
 669         return 0;
 670 }
 671
 672 /* Get/set timeout ioctl() operation */
 673 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
 674                                          unsigned long __user *p)
 675 {
 676         int rv;
 677         unsigned long ntimeout;
 678
 679         if ( (rv = get_user(ntimeout, p)) ||
 680              (rv = put_user(sbi->exp_timeout/HZ, p)) )
 681                 return rv;
 682
 683         if ( ntimeout > ULONG_MAX/HZ )
 684                 sbi->exp_timeout = 0;
 685         else
 686                 sbi->exp_timeout = ntimeout * HZ;
 687
 688         return 0;
 689 }
 690
 691 /* Return protocol version */
 692 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
 693 {
 694         return put_user(sbi->version, p);
 695 }
 696
 697 /* Return protocol sub version */
 698 static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
 699 {
 700         return put_user(sbi->sub_version, p);
 701 }
 702
 703 /*
 704  * Tells the daemon whether we need to reghost or not. Also, clears
 705  * the reghost_needed flag.
 706  */
 707 static inline int autofs4_ask_reghost(struct autofs_sb_info *sbi, int __user *p)
 708 {
 709         int status;
 710
 711         DPRINTK("returning %d", sbi->needs_reghost);
 712
 713         status = put_user(sbi->needs_reghost, p);
 714         if ( status )
 715                 return status;
 716
 717         sbi->needs_reghost = 0;
 718         return 0;
 719 }
 720
 721 /*
 722  * Enable / Disable reghosting ioctl() operation
 723  */
 724 static inline int autofs4_toggle_reghost(struct autofs_sb_info *sbi, int __user *p)
 725 {
 726         int status;
 727         int val;
 728
 729         status = get_user(val, p);
 730
 731         DPRINTK("reghost = %d", val);
 732
 733         if (status)
 734                 return status;
 735
 736         /* turn on/off reghosting, with the val */
 737         sbi->reghost_enabled = val;
 738         return 0;
 739 }
 740
 741 /*
 742 * Tells the daemon whether it can umount the autofs mount.
 743 */
 744 static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
 745 {
 746         int status = 0;
 747
 748         if (may_umount(mnt) == 0)
 749                 status = 1;
 750
 751         DPRINTK("returning %d", status);
 752
 753         status = put_user(status, p);
 754
 755         return status;
 756 }
 757
 758 /* Identify autofs4_dentries - this is so we can tell if there's
 759    an extra dentry refcount or not.  We only hold a refcount on the
 760    dentry if its non-negative (ie, d_inode != NULL)
 761 */
 762 int is_autofs4_dentry(struct dentry *dentry)
 763 {
 764         return dentry && dentry->d_inode &&
 765                 (dentry->d_op == &autofs4_root_dentry_operations ||
 766                  dentry->d_op == &autofs4_dentry_operations) &&
 767                 dentry->d_fsdata != NULL;
 768 }
 769
 770 /*
 771  * ioctl()'s on the root directory is the chief method for the daemon to
 772  * generate kernel reactions
 773  */
 774 static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
 775                              unsigned int cmd, unsigned long arg)
 776 {
 777         struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
 778         void __user *p = (void __user *)arg;
 779
 780         DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
 781                 cmd,arg,sbi,process_group(current));
 782
 783         if ( _IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
 784              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT )
 785                 return -ENOTTY;
 786
 787         if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
 788                 return -EPERM;
 789
 790         switch(cmd) {
 791         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
 792                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
 793         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
 794                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
 795         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
 796                 autofs4_catatonic_mode(sbi);
 797                 return 0;
 798         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
 799                 return autofs4_get_protover(sbi, p);
 800         case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
 801                 return autofs4_get_protosubver(sbi, p);
 802         case AUTOFS_IOC_SETTIMEOUT:
 803                 return autofs4_get_set_timeout(sbi, p);
 804
 805         case AUTOFS_IOC_TOGGLEREGHOST:
 806                 return autofs4_toggle_reghost(sbi, p);
 807         case AUTOFS_IOC_ASKREGHOST:
 808                 return autofs4_ask_reghost(sbi, p);
 809
 810         case AUTOFS_IOC_ASKUMOUNT:
 811                 return autofs4_ask_umount(filp->f_vfsmnt, p);
 812
 813         /* return a single thing to expire */
 814         case AUTOFS_IOC_EXPIRE:
 815                 return autofs4_expire_run(inode->i_sb,filp->f_vfsmnt,sbi, p);
 816         /* same as above, but can send multiple expires through pipe */
 817         case AUTOFS_IOC_EXPIRE_MULTI:
 818                 return autofs4_expire_multi(inode->i_sb,filp->f_vfsmnt,sbi, p);
 819
 820         default:
 821                 return -ENOSYS;
 822         }
 823 }