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 *ino = 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 (ino && (ino->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         /*
 327          * Wait for a pending mount, triggering one if there
 328          * isn't one already
 329          */
 330         if (dentry->d_inode == NULL) {
 331                 DPRINTK("waiting for mount name=%.*s",
 332                          dentry->d_name.len, dentry->d_name.name);
 333
 334                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 335
 336                 DPRINTK("mount done status=%d", status);
 337
 338                 if (status && dentry->d_inode)
 339                         return 0; /* Try to get the kernel to invalidate this dentry */
 340
 341                 /* Turn this into a real negative dentry? */
 342                 if (status == -ENOENT) {
 343                         dentry->d_time = jiffies + AUTOFS_NEGATIVE_TIMEOUT;
 344                         spin_lock(&dentry->d_lock);
 345                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 346                         spin_unlock(&dentry->d_lock);
 347                         return 1;
 348                 } else if (status) {
 349                         /* Return a negative dentry, but leave it "pending" */
 350                         return 1;
 351                 }
 352         /* Trigger mount for path component or follow link */
 353         } else if (flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY) ||
 354                         current->link_count) {
 355                 DPRINTK("waiting for mount name=%.*s",
 356                         dentry->d_name.len, dentry->d_name.name);
 357
 358                 spin_lock(&dentry->d_lock);
 359                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 360                 spin_unlock(&dentry->d_lock);
 361                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 362
 363                 DPRINTK("mount done status=%d", status);
 364
 365                 if (status) {
 366                         spin_lock(&dentry->d_lock);
 367                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 368                         spin_unlock(&dentry->d_lock);
 369                         return 0;
 370                 }
 371         }
 372
 373         /*
 374          * We don't update the usages for the autofs daemon itself, this
 375          * is necessary for recursive autofs mounts
 376          */
 377         if (!autofs4_oz_mode(sbi))
 378                 autofs4_update_usage(mnt, dentry);
 379
 380         spin_lock(&dentry->d_lock);
 381         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 382         spin_unlock(&dentry->d_lock);
 383         return 1;
 384 }
 385
 386 /*
 387  * Revalidate is called on every cache lookup.  Some of those
 388  * cache lookups may actually happen while the dentry is not
 389  * yet completely filled in, and revalidate has to delay such
 390  * lookups..
 391  */
 392 static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
 393 {
 394         struct inode *dir = dentry->d_parent->d_inode;
 395         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 396         int oz_mode = autofs4_oz_mode(sbi);
 397         int flags = nd ? nd->flags : 0;
 398         int status = 1;
 399
 400         /* Pending dentry */
 401         if (autofs4_ispending(dentry)) {
 402                 if (!oz_mode)
 403                         status = try_to_fill_dentry(nd->mnt, dentry, flags);
 404                 return status;
 405         }
 406
 407         /* Negative dentry.. invalidate if "old" */
 408         if (dentry->d_inode == NULL)
 409                 return (dentry->d_time - jiffies <= AUTOFS_NEGATIVE_TIMEOUT);
 410
 411         /* Check for a non-mountpoint directory with no contents */
 412         spin_lock(&dcache_lock);
 413         if (S_ISDIR(dentry->d_inode->i_mode) &&
 414             !d_mountpoint(dentry) &&
 415             list_empty(&dentry->d_subdirs)) {
 416                 DPRINTK("dentry=%p %.*s, emptydir",
 417                          dentry, dentry->d_name.len, dentry->d_name.name);
 418                 spin_unlock(&dcache_lock);
 419                 if (!oz_mode)
 420                         status = try_to_fill_dentry(nd->mnt, dentry, flags);
 421                 return status;
 422         }
 423         spin_unlock(&dcache_lock);
 424
 425         /* Update the usage list */
 426         if (!oz_mode)
 427                 autofs4_update_usage(nd->mnt, dentry);
 428
 429         return 1;
 430 }
 431
 432 static void autofs4_dentry_release(struct dentry *de)
 433 {
 434         struct autofs_info *inf;
 435
 436         DPRINTK("releasing %p", de);
 437
 438         inf = autofs4_dentry_ino(de);
 439         de->d_fsdata = NULL;
 440
 441         if (inf) {
 442                 inf->dentry = NULL;
 443                 inf->inode = NULL;
 444
 445                 autofs4_free_ino(inf);
 446         }
 447 }
 448
 449 /* For dentries of directories in the root dir */
 450 static struct dentry_operations autofs4_root_dentry_operations = {
 451         .d_revalidate   = autofs4_revalidate,
 452         .d_release      = autofs4_dentry_release,
 453 };
 454
 455 /* For other dentries */
 456 static struct dentry_operations autofs4_dentry_operations = {
 457         .d_revalidate   = autofs4_revalidate,
 458         .d_release      = autofs4_dentry_release,
 459 };
 460
 461 /* Lookups in the root directory */
 462 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 463 {
 464         struct autofs_sb_info *sbi;
 465         int oz_mode;
 466
 467         DPRINTK("name = %.*s",
 468                 dentry->d_name.len, dentry->d_name.name);
 469
 470         /* File name too long to exist */
 471         if (dentry->d_name.len > NAME_MAX)
 472                 return ERR_PTR(-ENAMETOOLONG);
 473
 474         sbi = autofs4_sbi(dir->i_sb);
 475         oz_mode = autofs4_oz_mode(sbi);
 476
 477         DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
 478                  current->pid, process_group(current), sbi->catatonic, oz_mode);
 479
 480         /*
 481          * Mark the dentry incomplete, but add it. This is needed so
 482          * that the VFS layer knows about the dentry, and we can count
 483          * on catching any lookups through the revalidate.
 484          *
 485          * Let all the hard work be done by the revalidate function that
 486          * needs to be able to do this anyway..
 487          *
 488          * We need to do this before we release the directory semaphore.
 489          */
 490         dentry->d_op = &autofs4_root_dentry_operations;
 491
 492         if (!oz_mode) {
 493                 spin_lock(&dentry->d_lock);
 494                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 495                 spin_unlock(&dentry->d_lock);
 496         }
 497         dentry->d_fsdata = NULL;
 498         d_add(dentry, NULL);
 499
 500         if (dentry->d_op && dentry->d_op->d_revalidate) {
 501                 mutex_unlock(&dir->i_mutex);
 502                 (dentry->d_op->d_revalidate)(dentry, nd);
 503                 mutex_lock(&dir->i_mutex);
 504         }
 505
 506         /*
 507          * If we are still pending, check if we had to handle
 508          * a signal. If so we can force a restart..
 509          */
 510         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 511                 /* See if we were interrupted */
 512                 if (signal_pending(current)) {
 513                         sigset_t *sigset = &current->pending.signal;
 514                         if (sigismember (sigset, SIGKILL) ||
 515                             sigismember (sigset, SIGQUIT) ||
 516                             sigismember (sigset, SIGINT)) {
 517                             return ERR_PTR(-ERESTARTNOINTR);
 518                         }
 519                 }
 520         }
 521
 522         /*
 523          * If this dentry is unhashed, then we shouldn't honour this
 524          * lookup even if the dentry is positive.  Returning ENOENT here
 525          * doesn't do the right thing for all system calls, but it should
 526          * be OK for the operations we permit from an autofs.
 527          */
 528         if (dentry->d_inode && d_unhashed(dentry))
 529                 return ERR_PTR(-ENOENT);
 530
 531         return NULL;
 532 }
 533
 534 static int autofs4_dir_symlink(struct inode *dir,
 535                                struct dentry *dentry,
 536                                const char *symname)
 537 {
 538         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 539         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 540         struct inode *inode;
 541         char *cp;
 542
 543         DPRINTK("%s <- %.*s", symname,
 544                 dentry->d_name.len, dentry->d_name.name);
 545
 546         if (!autofs4_oz_mode(sbi))
 547                 return -EACCES;
 548
 549         ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
 550         if (ino == NULL)
 551                 return -ENOSPC;
 552
 553         ino->size = strlen(symname);
 554         ino->u.symlink = cp = kmalloc(ino->size + 1, GFP_KERNEL);
 555
 556         if (cp == NULL) {
 557                 kfree(ino);
 558                 return -ENOSPC;
 559         }
 560
 561         strcpy(cp, symname);
 562
 563         inode = autofs4_get_inode(dir->i_sb, ino);
 564         d_instantiate(dentry, inode);
 565
 566         if (dir == dir->i_sb->s_root->d_inode)
 567                 dentry->d_op = &autofs4_root_dentry_operations;
 568         else
 569                 dentry->d_op = &autofs4_dentry_operations;
 570
 571         dentry->d_fsdata = ino;
 572         ino->dentry = dget(dentry);
 573         ino->inode = inode;
 574
 575         dir->i_mtime = CURRENT_TIME;
 576
 577         return 0;
 578 }
 579
 580 /*
 581  * NOTE!
 582  *
 583  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 584  * that the file no longer exists. However, doing that means that the
 585  * VFS layer can turn the dentry into a negative dentry.  We don't want
 586  * this, because since the unlink is probably the result of an expire.
 587  * We simply d_drop it, which allows the dentry lookup to remount it
 588  * if necessary.
 589  *
 590  * If a process is blocked on the dentry waiting for the expire to finish,
 591  * it will invalidate the dentry and try to mount with a new one.
 592  *
 593  * Also see autofs4_dir_rmdir()..
 594  */
 595 static int autofs4_dir_unlink(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         /* This allows root to remove symlinks */
 601         if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
 602                 return -EACCES;
 603
 604         dput(ino->dentry);
 605
 606         dentry->d_inode->i_size = 0;
 607         dentry->d_inode->i_nlink = 0;
 608
 609         dir->i_mtime = CURRENT_TIME;
 610
 611         d_drop(dentry);
 612
 613         return 0;
 614 }
 615
 616 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
 617 {
 618         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 619         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 620
 621         if (!autofs4_oz_mode(sbi))
 622                 return -EACCES;
 623
 624         spin_lock(&dcache_lock);
 625         if (!list_empty(&dentry->d_subdirs)) {
 626                 spin_unlock(&dcache_lock);
 627                 return -ENOTEMPTY;
 628         }
 629         spin_lock(&dentry->d_lock);
 630         __d_drop(dentry);
 631         spin_unlock(&dentry->d_lock);
 632         spin_unlock(&dcache_lock);
 633
 634         dput(ino->dentry);
 635
 636         dentry->d_inode->i_size = 0;
 637         dentry->d_inode->i_nlink = 0;
 638
 639         if (dir->i_nlink)
 640                 dir->i_nlink--;
 641
 642         return 0;
 643 }
 644
 645 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 646 {
 647         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 648         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 649         struct inode *inode;
 650
 651         if ( !autofs4_oz_mode(sbi) )
 652                 return -EACCES;
 653
 654         DPRINTK("dentry %p, creating %.*s",
 655                 dentry, dentry->d_name.len, dentry->d_name.name);
 656
 657         ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
 658         if (ino == NULL)
 659                 return -ENOSPC;
 660
 661         inode = autofs4_get_inode(dir->i_sb, ino);
 662         d_instantiate(dentry, inode);
 663
 664         if (dir == dir->i_sb->s_root->d_inode)
 665                 dentry->d_op = &autofs4_root_dentry_operations;
 666         else
 667                 dentry->d_op = &autofs4_dentry_operations;
 668
 669         dentry->d_fsdata = ino;
 670         ino->dentry = dget(dentry);
 671         ino->inode = inode;
 672         dir->i_nlink++;
 673         dir->i_mtime = CURRENT_TIME;
 674
 675         return 0;
 676 }
 677
 678 /* Get/set timeout ioctl() operation */
 679 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
 680                                          unsigned long __user *p)
 681 {
 682         int rv;
 683         unsigned long ntimeout;
 684
 685         if ( (rv = get_user(ntimeout, p)) ||
 686              (rv = put_user(sbi->exp_timeout/HZ, p)) )
 687                 return rv;
 688
 689         if ( ntimeout > ULONG_MAX/HZ )
 690                 sbi->exp_timeout = 0;
 691         else
 692                 sbi->exp_timeout = ntimeout * HZ;
 693
 694         return 0;
 695 }
 696
 697 /* Return protocol version */
 698 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
 699 {
 700         return put_user(sbi->version, p);
 701 }
 702
 703 /* Return protocol sub version */
 704 static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
 705 {
 706         return put_user(sbi->sub_version, p);
 707 }
 708
 709 /*
 710  * Tells the daemon whether we need to reghost or not. Also, clears
 711  * the reghost_needed flag.
 712  */
 713 static inline int autofs4_ask_reghost(struct autofs_sb_info *sbi, int __user *p)
 714 {
 715         int status;
 716
 717         DPRINTK("returning %d", sbi->needs_reghost);
 718
 719         status = put_user(sbi->needs_reghost, p);
 720         if ( status )
 721                 return status;
 722
 723         sbi->needs_reghost = 0;
 724         return 0;
 725 }
 726
 727 /*
 728  * Enable / Disable reghosting ioctl() operation
 729  */
 730 static inline int autofs4_toggle_reghost(struct autofs_sb_info *sbi, int __user *p)
 731 {
 732         int status;
 733         int val;
 734
 735         status = get_user(val, p);
 736
 737         DPRINTK("reghost = %d", val);
 738
 739         if (status)
 740                 return status;
 741
 742         /* turn on/off reghosting, with the val */
 743         sbi->reghost_enabled = val;
 744         return 0;
 745 }
 746
 747 /*
 748 * Tells the daemon whether it can umount the autofs mount.
 749 */
 750 static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
 751 {
 752         int status = 0;
 753
 754         if (may_umount(mnt) == 0)
 755                 status = 1;
 756
 757         DPRINTK("returning %d", status);
 758
 759         status = put_user(status, p);
 760
 761         return status;
 762 }
 763
 764 /* Identify autofs4_dentries - this is so we can tell if there's
 765    an extra dentry refcount or not.  We only hold a refcount on the
 766    dentry if its non-negative (ie, d_inode != NULL)
 767 */
 768 int is_autofs4_dentry(struct dentry *dentry)
 769 {
 770         return dentry && dentry->d_inode &&
 771                 (dentry->d_op == &autofs4_root_dentry_operations ||
 772                  dentry->d_op == &autofs4_dentry_operations) &&
 773                 dentry->d_fsdata != NULL;
 774 }
 775
 776 /*
 777  * ioctl()'s on the root directory is the chief method for the daemon to
 778  * generate kernel reactions
 779  */
 780 static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
 781                              unsigned int cmd, unsigned long arg)
 782 {
 783         struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
 784         void __user *p = (void __user *)arg;
 785
 786         DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
 787                 cmd,arg,sbi,process_group(current));
 788
 789         if ( _IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
 790              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT )
 791                 return -ENOTTY;
 792
 793         if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
 794                 return -EPERM;
 795
 796         switch(cmd) {
 797         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
 798                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
 799         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
 800                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
 801         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
 802                 autofs4_catatonic_mode(sbi);
 803                 return 0;
 804         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
 805                 return autofs4_get_protover(sbi, p);
 806         case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
 807                 return autofs4_get_protosubver(sbi, p);
 808         case AUTOFS_IOC_SETTIMEOUT:
 809                 return autofs4_get_set_timeout(sbi, p);
 810
 811         case AUTOFS_IOC_TOGGLEREGHOST:
 812                 return autofs4_toggle_reghost(sbi, p);
 813         case AUTOFS_IOC_ASKREGHOST:
 814                 return autofs4_ask_reghost(sbi, p);
 815
 816         case AUTOFS_IOC_ASKUMOUNT:
 817                 return autofs4_ask_umount(filp->f_vfsmnt, p);
 818
 819         /* return a single thing to expire */
 820         case AUTOFS_IOC_EXPIRE:
 821                 return autofs4_expire_run(inode->i_sb,filp->f_vfsmnt,sbi, p);
 822         /* same as above, but can send multiple expires through pipe */
 823         case AUTOFS_IOC_EXPIRE_MULTI:
 824                 return autofs4_expire_multi(inode->i_sb,filp->f_vfsmnt,sbi, p);
 825
 826         default:
 827                 return -ENOSYS;
 828         }
 829 }