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