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