fs/autofs4/root.c

   1 /* -*- c -*- --------------------------------------------------------------- *
   2  *
   3  * linux/fs/autofs/root.c
   4  *
   5  *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
   6  *  Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
   7  *  Copyright 2001-2006 Ian Kent <raven@themaw.net>
   8  *
   9  * This file is part of the Linux kernel and is made available under
  10  * the terms of the GNU General Public License, version 2, or at your
  11  * option, any later version, incorporated herein by reference.
  12  *
  13  * ------------------------------------------------------------------------- */
  14
  15 #include <linux/capability.h>
  16 #include <linux/errno.h>
  17 #include <linux/stat.h>
  18 #include <linux/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 void *autofs4_follow_link(struct dentry *, struct nameidata *);
  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_indirect_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_direct_root_inode_operations = {
  59         .lookup         = autofs4_lookup,
  60         .follow_link    = autofs4_follow_link,
  61 };
  62
  63 struct inode_operations autofs4_dir_inode_operations = {
  64         .lookup         = autofs4_lookup,
  65         .unlink         = autofs4_dir_unlink,
  66         .symlink        = autofs4_dir_symlink,
  67         .mkdir          = autofs4_dir_mkdir,
  68         .rmdir          = autofs4_dir_rmdir,
  69 };
  70
  71 static int autofs4_root_readdir(struct file *file, void *dirent,
  72                                 filldir_t filldir)
  73 {
  74         struct autofs_sb_info *sbi = autofs4_sbi(file->f_dentry->d_sb);
  75         int oz_mode = autofs4_oz_mode(sbi);
  76
  77         DPRINTK("called, filp->f_pos = %lld", file->f_pos);
  78
  79         /*
  80          * Don't set reghost flag if:
  81          * 1) f_pos is larger than zero -- we've already been here.
  82          * 2) we haven't even enabled reghosting in the 1st place.
  83          * 3) this is the daemon doing a readdir
  84          */
  85         if (oz_mode && file->f_pos == 0 && sbi->reghost_enabled)
  86                 sbi->needs_reghost = 1;
  87
  88         DPRINTK("needs_reghost = %d", sbi->needs_reghost);
  89
  90         return dcache_readdir(file, dirent, filldir);
  91 }
  92
  93 static int autofs4_dir_open(struct inode *inode, struct file *file)
  94 {
  95         struct dentry *dentry = file->f_dentry;
  96         struct vfsmount *mnt = file->f_vfsmnt;
  97         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
  98         struct dentry *cursor;
  99         int status;
 100
 101         status = dcache_dir_open(inode, file);
 102         if (status)
 103                 goto out;
 104
 105         cursor = file->private_data;
 106         cursor->d_fsdata = NULL;
 107
 108         DPRINTK("file=%p dentry=%p %.*s",
 109                 file, dentry, dentry->d_name.len, dentry->d_name.name);
 110
 111         if (autofs4_oz_mode(sbi))
 112                 goto out;
 113
 114         if (autofs4_ispending(dentry)) {
 115                 DPRINTK("dentry busy");
 116                 dcache_dir_close(inode, file);
 117                 status = -EBUSY;
 118                 goto out;
 119         }
 120
 121         status = -ENOENT;
 122         if (!d_mountpoint(dentry) && dentry->d_op && dentry->d_op->d_revalidate) {
 123                 struct nameidata nd;
 124                 int empty, ret;
 125
 126                 /* In case there are stale directory dentrys from a failed mount */
 127                 spin_lock(&dcache_lock);
 128                 empty = list_empty(&dentry->d_subdirs);
 129                 spin_unlock(&dcache_lock);
 130
 131                 if (!empty)
 132                         d_invalidate(dentry);
 133
 134                 nd.flags = LOOKUP_DIRECTORY;
 135                 ret = (dentry->d_op->d_revalidate)(dentry, &nd);
 136
 137                 if (!ret) {
 138                         dcache_dir_close(inode, file);
 139                         goto out;
 140                 }
 141         }
 142
 143         if (d_mountpoint(dentry)) {
 144                 struct file *fp = NULL;
 145                 struct vfsmount *fp_mnt = mntget(mnt);
 146                 struct dentry *fp_dentry = dget(dentry);
 147
 148                 if (!autofs4_follow_mount(&fp_mnt, &fp_dentry)) {
 149                         dput(fp_dentry);
 150                         mntput(fp_mnt);
 151                         dcache_dir_close(inode, file);
 152                         goto out;
 153                 }
 154
 155                 fp = dentry_open(fp_dentry, fp_mnt, file->f_flags);
 156                 status = PTR_ERR(fp);
 157                 if (IS_ERR(fp)) {
 158                         dcache_dir_close(inode, file);
 159                         goto out;
 160                 }
 161                 cursor->d_fsdata = fp;
 162         }
 163         return 0;
 164 out:
 165         return status;
 166 }
 167
 168 static int autofs4_dir_close(struct inode *inode, struct file *file)
 169 {
 170         struct dentry *dentry = file->f_dentry;
 171         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 172         struct dentry *cursor = file->private_data;
 173         int status = 0;
 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                 status = -EBUSY;
 184                 goto out;
 185         }
 186
 187         if (d_mountpoint(dentry)) {
 188                 struct file *fp = cursor->d_fsdata;
 189                 if (!fp) {
 190                         status = -ENOENT;
 191                         goto out;
 192                 }
 193                 filp_close(fp, current->files);
 194         }
 195 out:
 196         dcache_dir_close(inode, file);
 197         return status;
 198 }
 199
 200 static int autofs4_dir_readdir(struct file *file, void *dirent, filldir_t filldir)
 201 {
 202         struct dentry *dentry = file->f_dentry;
 203         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 204         struct dentry *cursor = file->private_data;
 205         int status;
 206
 207         DPRINTK("file=%p dentry=%p %.*s",
 208                 file, dentry, dentry->d_name.len, dentry->d_name.name);
 209
 210         if (autofs4_oz_mode(sbi))
 211                 goto out;
 212
 213         if (autofs4_ispending(dentry)) {
 214                 DPRINTK("dentry busy");
 215                 return -EBUSY;
 216         }
 217
 218         if (d_mountpoint(dentry)) {
 219                 struct file *fp = cursor->d_fsdata;
 220
 221                 if (!fp)
 222                         return -ENOENT;
 223
 224                 if (!fp->f_op || !fp->f_op->readdir)
 225                         goto out;
 226
 227                 status = vfs_readdir(fp, filldir, dirent);
 228                 file->f_pos = fp->f_pos;
 229                 if (status)
 230                         autofs4_copy_atime(file, fp);
 231                 return status;
 232         }
 233 out:
 234         return dcache_readdir(file, dirent, filldir);
 235 }
 236
 237 static int try_to_fill_dentry(struct dentry *dentry, int flags)
 238 {
 239         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 240         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 241         int status = 0;
 242
 243         /* Block on any pending expiry here; invalidate the dentry
 244            when expiration is done to trigger mount request with a new
 245            dentry */
 246         if (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
 247                 DPRINTK("waiting for expire %p name=%.*s",
 248                          dentry, dentry->d_name.len, dentry->d_name.name);
 249
 250                 status = autofs4_wait(sbi, dentry, NFY_NONE);
 251
 252                 DPRINTK("expire done status=%d", status);
 253
 254                 /*
 255                  * If the directory still exists the mount request must
 256                  * continue otherwise it can't be followed at the right
 257                  * time during the walk.
 258                  */
 259                 status = d_invalidate(dentry);
 260                 if (status != -EBUSY)
 261                         return -ENOENT;
 262         }
 263
 264         DPRINTK("dentry=%p %.*s ino=%p",
 265                  dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode);
 266
 267         /*
 268          * Wait for a pending mount, triggering one if there
 269          * isn't one already
 270          */
 271         if (dentry->d_inode == NULL) {
 272                 DPRINTK("waiting for mount name=%.*s",
 273                          dentry->d_name.len, dentry->d_name.name);
 274
 275                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 276
 277                 DPRINTK("mount done status=%d", status);
 278
 279                 if (status && dentry->d_inode)
 280                         return status; /* Try to get the kernel to invalidate this dentry */
 281
 282                 /* Turn this into a real negative dentry? */
 283                 if (status == -ENOENT) {
 284                         spin_lock(&dentry->d_lock);
 285                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 286                         spin_unlock(&dentry->d_lock);
 287                         return status;
 288                 } else if (status) {
 289                         /* Return a negative dentry, but leave it "pending" */
 290                         return status;
 291                 }
 292         /* Trigger mount for path component or follow link */
 293         } else if (flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY) ||
 294                         current->link_count) {
 295                 DPRINTK("waiting for mount name=%.*s",
 296                         dentry->d_name.len, dentry->d_name.name);
 297
 298                 spin_lock(&dentry->d_lock);
 299                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 300                 spin_unlock(&dentry->d_lock);
 301                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 302
 303                 DPRINTK("mount done status=%d", status);
 304
 305                 if (status) {
 306                         spin_lock(&dentry->d_lock);
 307                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 308                         spin_unlock(&dentry->d_lock);
 309                         return status;
 310                 }
 311         }
 312
 313         /* Initialize expiry counter after successful mount */
 314         if (ino)
 315                 ino->last_used = jiffies;
 316
 317         spin_lock(&dentry->d_lock);
 318         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 319         spin_unlock(&dentry->d_lock);
 320         return status;
 321 }
 322
 323 /* For autofs direct mounts the follow link triggers the mount */
 324 static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
 325 {
 326         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 327         int oz_mode = autofs4_oz_mode(sbi);
 328         unsigned int lookup_type;
 329         int status;
 330
 331         DPRINTK("dentry=%p %.*s oz_mode=%d nd->flags=%d",
 332                 dentry, dentry->d_name.len, dentry->d_name.name, oz_mode,
 333                 nd->flags);
 334
 335         /* If it's our master or we shouldn't trigger a mount we're done */
 336         lookup_type = nd->flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY);
 337         if (oz_mode || !lookup_type)
 338                 goto done;
 339
 340         status = try_to_fill_dentry(dentry, 0);
 341         if (status)
 342                 goto out_error;
 343
 344         if (!autofs4_follow_mount(&nd->mnt, &nd->dentry)) {
 345                 status = -ENOENT;
 346                 goto out_error;
 347         }
 348
 349 done:
 350         return NULL;
 351
 352 out_error:
 353         path_release(nd);
 354         return ERR_PTR(status);
 355 }
 356
 357 /*
 358  * Revalidate is called on every cache lookup.  Some of those
 359  * cache lookups may actually happen while the dentry is not
 360  * yet completely filled in, and revalidate has to delay such
 361  * lookups..
 362  */
 363 static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
 364 {
 365         struct inode *dir = dentry->d_parent->d_inode;
 366         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 367         int oz_mode = autofs4_oz_mode(sbi);
 368         int flags = nd ? nd->flags : 0;
 369         int status = 0;
 370
 371         /* Pending dentry */
 372         if (autofs4_ispending(dentry)) {
 373                 if (!oz_mode)
 374                         status = try_to_fill_dentry(dentry, flags);
 375                 return !status;
 376         }
 377
 378         /* Negative dentry.. invalidate if "old" */
 379         if (dentry->d_inode == NULL)
 380                 return 0;
 381
 382         /* Check for a non-mountpoint directory with no contents */
 383         spin_lock(&dcache_lock);
 384         if (S_ISDIR(dentry->d_inode->i_mode) &&
 385             !d_mountpoint(dentry) &&
 386             __simple_empty(dentry)) {
 387                 DPRINTK("dentry=%p %.*s, emptydir",
 388                          dentry, dentry->d_name.len, dentry->d_name.name);
 389                 spin_unlock(&dcache_lock);
 390                 if (!oz_mode)
 391                         status = try_to_fill_dentry(dentry, flags);
 392                 return !status;
 393         }
 394         spin_unlock(&dcache_lock);
 395
 396         return 1;
 397 }
 398
 399 void autofs4_dentry_release(struct dentry *de)
 400 {
 401         struct autofs_info *inf;
 402
 403         DPRINTK("releasing %p", de);
 404
 405         inf = autofs4_dentry_ino(de);
 406         de->d_fsdata = NULL;
 407
 408         if (inf) {
 409                 inf->dentry = NULL;
 410                 inf->inode = NULL;
 411
 412                 autofs4_free_ino(inf);
 413         }
 414 }
 415
 416 /* For dentries of directories in the root dir */
 417 static struct dentry_operations autofs4_root_dentry_operations = {
 418         .d_revalidate   = autofs4_revalidate,
 419         .d_release      = autofs4_dentry_release,
 420 };
 421
 422 /* For other dentries */
 423 static struct dentry_operations autofs4_dentry_operations = {
 424         .d_revalidate   = autofs4_revalidate,
 425         .d_release      = autofs4_dentry_release,
 426 };
 427
 428 /* Lookups in the root directory */
 429 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 430 {
 431         struct autofs_sb_info *sbi;
 432         int oz_mode;
 433
 434         DPRINTK("name = %.*s",
 435                 dentry->d_name.len, dentry->d_name.name);
 436
 437         /* File name too long to exist */
 438         if (dentry->d_name.len > NAME_MAX)
 439                 return ERR_PTR(-ENAMETOOLONG);
 440
 441         sbi = autofs4_sbi(dir->i_sb);
 442         oz_mode = autofs4_oz_mode(sbi);
 443
 444         DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
 445                  current->pid, process_group(current), sbi->catatonic, oz_mode);
 446
 447         /*
 448          * Mark the dentry incomplete, but add it. This is needed so
 449          * that the VFS layer knows about the dentry, and we can count
 450          * on catching any lookups through the revalidate.
 451          *
 452          * Let all the hard work be done by the revalidate function that
 453          * needs to be able to do this anyway..
 454          *
 455          * We need to do this before we release the directory semaphore.
 456          */
 457         dentry->d_op = &autofs4_root_dentry_operations;
 458
 459         if (!oz_mode) {
 460                 spin_lock(&dentry->d_lock);
 461                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 462                 spin_unlock(&dentry->d_lock);
 463         }
 464         dentry->d_fsdata = NULL;
 465         d_add(dentry, NULL);
 466
 467         if (dentry->d_op && dentry->d_op->d_revalidate) {
 468                 mutex_unlock(&dir->i_mutex);
 469                 (dentry->d_op->d_revalidate)(dentry, nd);
 470                 mutex_lock(&dir->i_mutex);
 471         }
 472
 473         /*
 474          * If we are still pending, check if we had to handle
 475          * a signal. If so we can force a restart..
 476          */
 477         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 478                 /* See if we were interrupted */
 479                 if (signal_pending(current)) {
 480                         sigset_t *sigset = &current->pending.signal;
 481                         if (sigismember (sigset, SIGKILL) ||
 482                             sigismember (sigset, SIGQUIT) ||
 483                             sigismember (sigset, SIGINT)) {
 484                             return ERR_PTR(-ERESTARTNOINTR);
 485                         }
 486                 }
 487         }
 488
 489         /*
 490          * If this dentry is unhashed, then we shouldn't honour this
 491          * lookup even if the dentry is positive.  Returning ENOENT here
 492          * doesn't do the right thing for all system calls, but it should
 493          * be OK for the operations we permit from an autofs.
 494          */
 495         if (dentry->d_inode && d_unhashed(dentry))
 496                 return ERR_PTR(-ENOENT);
 497
 498         return NULL;
 499 }
 500
 501 static int autofs4_dir_symlink(struct inode *dir,
 502                                struct dentry *dentry,
 503                                const char *symname)
 504 {
 505         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 506         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 507         struct autofs_info *p_ino;
 508         struct inode *inode;
 509         char *cp;
 510
 511         DPRINTK("%s <- %.*s", symname,
 512                 dentry->d_name.len, dentry->d_name.name);
 513
 514         if (!autofs4_oz_mode(sbi))
 515                 return -EACCES;
 516
 517         ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
 518         if (ino == NULL)
 519                 return -ENOSPC;
 520
 521         ino->size = strlen(symname);
 522         ino->u.symlink = cp = kmalloc(ino->size + 1, GFP_KERNEL);
 523
 524         if (cp == NULL) {
 525                 kfree(ino);
 526                 return -ENOSPC;
 527         }
 528
 529         strcpy(cp, symname);
 530
 531         inode = autofs4_get_inode(dir->i_sb, ino);
 532         d_instantiate(dentry, inode);
 533
 534         if (dir == dir->i_sb->s_root->d_inode)
 535                 dentry->d_op = &autofs4_root_dentry_operations;
 536         else
 537                 dentry->d_op = &autofs4_dentry_operations;
 538
 539         dentry->d_fsdata = ino;
 540         ino->dentry = dget(dentry);
 541         atomic_inc(&ino->count);
 542         p_ino = autofs4_dentry_ino(dentry->d_parent);
 543         if (p_ino && dentry->d_parent != dentry)
 544                 atomic_inc(&p_ino->count);
 545         ino->inode = inode;
 546
 547         dir->i_mtime = CURRENT_TIME;
 548
 549         return 0;
 550 }
 551
 552 /*
 553  * NOTE!
 554  *
 555  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 556  * that the file no longer exists. However, doing that means that the
 557  * VFS layer can turn the dentry into a negative dentry.  We don't want
 558  * this, because since the unlink is probably the result of an expire.
 559  * We simply d_drop it, which allows the dentry lookup to remount it
 560  * if necessary.
 561  *
 562  * If a process is blocked on the dentry waiting for the expire to finish,
 563  * it will invalidate the dentry and try to mount with a new one.
 564  *
 565  * Also see autofs4_dir_rmdir()..
 566  */
 567 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
 568 {
 569         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 570         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 571         struct autofs_info *p_ino;
 572
 573         /* This allows root to remove symlinks */
 574         if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
 575                 return -EACCES;
 576
 577         if (atomic_dec_and_test(&ino->count)) {
 578                 p_ino = autofs4_dentry_ino(dentry->d_parent);
 579                 if (p_ino && dentry->d_parent != dentry)
 580                         atomic_dec(&p_ino->count);
 581         }
 582         dput(ino->dentry);
 583
 584         dentry->d_inode->i_size = 0;
 585         dentry->d_inode->i_nlink = 0;
 586
 587         dir->i_mtime = CURRENT_TIME;
 588
 589         d_drop(dentry);
 590
 591         return 0;
 592 }
 593
 594 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
 595 {
 596         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 597         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 598         struct autofs_info *p_ino;
 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         if (atomic_dec_and_test(&ino->count)) {
 614                 p_ino = autofs4_dentry_ino(dentry->d_parent);
 615                 if (p_ino && dentry->d_parent != dentry)
 616                         atomic_dec(&p_ino->count);
 617         }
 618         dput(ino->dentry);
 619         dentry->d_inode->i_size = 0;
 620         dentry->d_inode->i_nlink = 0;
 621
 622         if (dir->i_nlink)
 623                 dir->i_nlink--;
 624
 625         return 0;
 626 }
 627
 628 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 629 {
 630         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 631         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 632         struct autofs_info *p_ino;
 633         struct inode *inode;
 634
 635         if ( !autofs4_oz_mode(sbi) )
 636                 return -EACCES;
 637
 638         DPRINTK("dentry %p, creating %.*s",
 639                 dentry, dentry->d_name.len, dentry->d_name.name);
 640
 641         ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
 642         if (ino == NULL)
 643                 return -ENOSPC;
 644
 645         inode = autofs4_get_inode(dir->i_sb, ino);
 646         d_instantiate(dentry, inode);
 647
 648         if (dir == dir->i_sb->s_root->d_inode)
 649                 dentry->d_op = &autofs4_root_dentry_operations;
 650         else
 651                 dentry->d_op = &autofs4_dentry_operations;
 652
 653         dentry->d_fsdata = ino;
 654         ino->dentry = dget(dentry);
 655         atomic_inc(&ino->count);
 656         p_ino = autofs4_dentry_ino(dentry->d_parent);
 657         if (p_ino && dentry->d_parent != dentry)
 658                 atomic_inc(&p_ino->count);
 659         ino->inode = inode;
 660         dir->i_nlink++;
 661         dir->i_mtime = CURRENT_TIME;
 662
 663         return 0;
 664 }
 665
 666 /* Get/set timeout ioctl() operation */
 667 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
 668                                          unsigned long __user *p)
 669 {
 670         int rv;
 671         unsigned long ntimeout;
 672
 673         if ( (rv = get_user(ntimeout, p)) ||
 674              (rv = put_user(sbi->exp_timeout/HZ, p)) )
 675                 return rv;
 676
 677         if ( ntimeout > ULONG_MAX/HZ )
 678                 sbi->exp_timeout = 0;
 679         else
 680                 sbi->exp_timeout = ntimeout * HZ;
 681
 682         return 0;
 683 }
 684
 685 /* Return protocol version */
 686 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
 687 {
 688         return put_user(sbi->version, p);
 689 }
 690
 691 /* Return protocol sub version */
 692 static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
 693 {
 694         return put_user(sbi->sub_version, p);
 695 }
 696
 697 /*
 698  * Tells the daemon whether we need to reghost or not. Also, clears
 699  * the reghost_needed flag.
 700  */
 701 static inline int autofs4_ask_reghost(struct autofs_sb_info *sbi, int __user *p)
 702 {
 703         int status;
 704
 705         DPRINTK("returning %d", sbi->needs_reghost);
 706
 707         status = put_user(sbi->needs_reghost, p);
 708         if ( status )
 709                 return status;
 710
 711         sbi->needs_reghost = 0;
 712         return 0;
 713 }
 714
 715 /*
 716  * Enable / Disable reghosting ioctl() operation
 717  */
 718 static inline int autofs4_toggle_reghost(struct autofs_sb_info *sbi, int __user *p)
 719 {
 720         int status;
 721         int val;
 722
 723         status = get_user(val, p);
 724
 725         DPRINTK("reghost = %d", val);
 726
 727         if (status)
 728                 return status;
 729
 730         /* turn on/off reghosting, with the val */
 731         sbi->reghost_enabled = val;
 732         return 0;
 733 }
 734
 735 /*
 736 * Tells the daemon whether it can umount the autofs mount.
 737 */
 738 static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
 739 {
 740         int status = 0;
 741
 742         if (may_umount(mnt))
 743                 status = 1;
 744
 745         DPRINTK("returning %d", status);
 746
 747         status = put_user(status, p);
 748
 749         return status;
 750 }
 751
 752 /* Identify autofs4_dentries - this is so we can tell if there's
 753    an extra dentry refcount or not.  We only hold a refcount on the
 754    dentry if its non-negative (ie, d_inode != NULL)
 755 */
 756 int is_autofs4_dentry(struct dentry *dentry)
 757 {
 758         return dentry && dentry->d_inode &&
 759                 (dentry->d_op == &autofs4_root_dentry_operations ||
 760                  dentry->d_op == &autofs4_dentry_operations) &&
 761                 dentry->d_fsdata != NULL;
 762 }
 763
 764 /*
 765  * ioctl()'s on the root directory is the chief method for the daemon to
 766  * generate kernel reactions
 767  */
 768 static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
 769                              unsigned int cmd, unsigned long arg)
 770 {
 771         struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
 772         void __user *p = (void __user *)arg;
 773
 774         DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
 775                 cmd,arg,sbi,process_group(current));
 776
 777         if ( _IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
 778              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT )
 779                 return -ENOTTY;
 780
 781         if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
 782                 return -EPERM;
 783
 784         switch(cmd) {
 785         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
 786                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
 787         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
 788                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
 789         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
 790                 autofs4_catatonic_mode(sbi);
 791                 return 0;
 792         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
 793                 return autofs4_get_protover(sbi, p);
 794         case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
 795                 return autofs4_get_protosubver(sbi, p);
 796         case AUTOFS_IOC_SETTIMEOUT:
 797                 return autofs4_get_set_timeout(sbi, p);
 798
 799         case AUTOFS_IOC_TOGGLEREGHOST:
 800                 return autofs4_toggle_reghost(sbi, p);
 801         case AUTOFS_IOC_ASKREGHOST:
 802                 return autofs4_ask_reghost(sbi, p);
 803
 804         case AUTOFS_IOC_ASKUMOUNT:
 805                 return autofs4_ask_umount(filp->f_vfsmnt, p);
 806
 807         /* return a single thing to expire */
 808         case AUTOFS_IOC_EXPIRE:
 809                 return autofs4_expire_run(inode->i_sb,filp->f_vfsmnt,sbi, p);
 810         /* same as above, but can send multiple expires through pipe */
 811         case AUTOFS_IOC_EXPIRE_MULTI:
 812                 return autofs4_expire_multi(inode->i_sb,filp->f_vfsmnt,sbi, p);
 813
 814         default:
 815                 return -ENOSYS;
 816         }
 817 }