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 const 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 const 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         .unlink         = autofs4_dir_unlink,
  61         .mkdir          = autofs4_dir_mkdir,
  62         .rmdir          = autofs4_dir_rmdir,
  63         .follow_link    = autofs4_follow_link,
  64 };
  65
  66 struct inode_operations autofs4_dir_inode_operations = {
  67         .lookup         = autofs4_lookup,
  68         .unlink         = autofs4_dir_unlink,
  69         .symlink        = autofs4_dir_symlink,
  70         .mkdir          = autofs4_dir_mkdir,
  71         .rmdir          = autofs4_dir_rmdir,
  72 };
  73
  74 static int autofs4_root_readdir(struct file *file, void *dirent,
  75                                 filldir_t filldir)
  76 {
  77         struct autofs_sb_info *sbi = autofs4_sbi(file->f_dentry->d_sb);
  78         int oz_mode = autofs4_oz_mode(sbi);
  79
  80         DPRINTK("called, filp->f_pos = %lld", file->f_pos);
  81
  82         /*
  83          * Don't set reghost flag if:
  84          * 1) f_pos is larger than zero -- we've already been here.
  85          * 2) we haven't even enabled reghosting in the 1st place.
  86          * 3) this is the daemon doing a readdir
  87          */
  88         if (oz_mode && file->f_pos == 0 && sbi->reghost_enabled)
  89                 sbi->needs_reghost = 1;
  90
  91         DPRINTK("needs_reghost = %d", sbi->needs_reghost);
  92
  93         return dcache_readdir(file, dirent, filldir);
  94 }
  95
  96 static int autofs4_dir_open(struct inode *inode, struct file *file)
  97 {
  98         struct dentry *dentry = file->f_dentry;
  99         struct vfsmount *mnt = file->f_vfsmnt;
 100         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 101         struct dentry *cursor;
 102         int status;
 103
 104         status = dcache_dir_open(inode, file);
 105         if (status)
 106                 goto out;
 107
 108         cursor = file->private_data;
 109         cursor->d_fsdata = NULL;
 110
 111         DPRINTK("file=%p dentry=%p %.*s",
 112                 file, dentry, dentry->d_name.len, dentry->d_name.name);
 113
 114         if (autofs4_oz_mode(sbi))
 115                 goto out;
 116
 117         if (autofs4_ispending(dentry)) {
 118                 DPRINTK("dentry busy");
 119                 dcache_dir_close(inode, file);
 120                 status = -EBUSY;
 121                 goto out;
 122         }
 123
 124         status = -ENOENT;
 125         if (!d_mountpoint(dentry) && dentry->d_op && dentry->d_op->d_revalidate) {
 126                 struct nameidata nd;
 127                 int empty, ret;
 128
 129                 /* In case there are stale directory dentrys from a failed mount */
 130                 spin_lock(&dcache_lock);
 131                 empty = list_empty(&dentry->d_subdirs);
 132                 spin_unlock(&dcache_lock);
 133
 134                 if (!empty)
 135                         d_invalidate(dentry);
 136
 137                 nd.flags = LOOKUP_DIRECTORY;
 138                 ret = (dentry->d_op->d_revalidate)(dentry, &nd);
 139
 140                 if (!ret) {
 141                         dcache_dir_close(inode, file);
 142                         goto out;
 143                 }
 144         }
 145
 146         if (d_mountpoint(dentry)) {
 147                 struct file *fp = NULL;
 148                 struct vfsmount *fp_mnt = mntget(mnt);
 149                 struct dentry *fp_dentry = dget(dentry);
 150
 151                 if (!autofs4_follow_mount(&fp_mnt, &fp_dentry)) {
 152                         dput(fp_dentry);
 153                         mntput(fp_mnt);
 154                         dcache_dir_close(inode, file);
 155                         goto out;
 156                 }
 157
 158                 fp = dentry_open(fp_dentry, fp_mnt, file->f_flags);
 159                 status = PTR_ERR(fp);
 160                 if (IS_ERR(fp)) {
 161                         dcache_dir_close(inode, file);
 162                         goto out;
 163                 }
 164                 cursor->d_fsdata = fp;
 165         }
 166         return 0;
 167 out:
 168         return status;
 169 }
 170
 171 static int autofs4_dir_close(struct inode *inode, struct file *file)
 172 {
 173         struct dentry *dentry = file->f_dentry;
 174         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 175         struct dentry *cursor = file->private_data;
 176         int status = 0;
 177
 178         DPRINTK("file=%p dentry=%p %.*s",
 179                 file, dentry, dentry->d_name.len, dentry->d_name.name);
 180
 181         if (autofs4_oz_mode(sbi))
 182                 goto out;
 183
 184         if (autofs4_ispending(dentry)) {
 185                 DPRINTK("dentry busy");
 186                 status = -EBUSY;
 187                 goto out;
 188         }
 189
 190         if (d_mountpoint(dentry)) {
 191                 struct file *fp = cursor->d_fsdata;
 192                 if (!fp) {
 193                         status = -ENOENT;
 194                         goto out;
 195                 }
 196                 filp_close(fp, current->files);
 197         }
 198 out:
 199         dcache_dir_close(inode, file);
 200         return status;
 201 }
 202
 203 static int autofs4_dir_readdir(struct file *file, void *dirent, filldir_t filldir)
 204 {
 205         struct dentry *dentry = file->f_dentry;
 206         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 207         struct dentry *cursor = file->private_data;
 208         int status;
 209
 210         DPRINTK("file=%p dentry=%p %.*s",
 211                 file, dentry, dentry->d_name.len, dentry->d_name.name);
 212
 213         if (autofs4_oz_mode(sbi))
 214                 goto out;
 215
 216         if (autofs4_ispending(dentry)) {
 217                 DPRINTK("dentry busy");
 218                 return -EBUSY;
 219         }
 220
 221         if (d_mountpoint(dentry)) {
 222                 struct file *fp = cursor->d_fsdata;
 223
 224                 if (!fp)
 225                         return -ENOENT;
 226
 227                 if (!fp->f_op || !fp->f_op->readdir)
 228                         goto out;
 229
 230                 status = vfs_readdir(fp, filldir, dirent);
 231                 file->f_pos = fp->f_pos;
 232                 if (status)
 233                         autofs4_copy_atime(file, fp);
 234                 return status;
 235         }
 236 out:
 237         return dcache_readdir(file, dirent, filldir);
 238 }
 239
 240 static int try_to_fill_dentry(struct dentry *dentry, int flags)
 241 {
 242         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 243         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 244         int status = 0;
 245
 246         /* Block on any pending expiry here; invalidate the dentry
 247            when expiration is done to trigger mount request with a new
 248            dentry */
 249         if (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
 250                 DPRINTK("waiting for expire %p name=%.*s",
 251                          dentry, dentry->d_name.len, dentry->d_name.name);
 252
 253                 status = autofs4_wait(sbi, dentry, NFY_NONE);
 254
 255                 DPRINTK("expire done status=%d", status);
 256
 257                 /*
 258                  * If the directory still exists the mount request must
 259                  * continue otherwise it can't be followed at the right
 260                  * time during the walk.
 261                  */
 262                 status = d_invalidate(dentry);
 263                 if (status != -EBUSY)
 264                         return -ENOENT;
 265         }
 266
 267         DPRINTK("dentry=%p %.*s ino=%p",
 268                  dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode);
 269
 270         /*
 271          * Wait for a pending mount, triggering one if there
 272          * isn't one already
 273          */
 274         if (dentry->d_inode == NULL) {
 275                 DPRINTK("waiting for mount name=%.*s",
 276                          dentry->d_name.len, dentry->d_name.name);
 277
 278                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 279
 280                 DPRINTK("mount done status=%d", status);
 281
 282                 if (status && dentry->d_inode)
 283                         return status; /* Try to get the kernel to invalidate this dentry */
 284
 285                 /* Turn this into a real negative dentry? */
 286                 if (status == -ENOENT) {
 287                         spin_lock(&dentry->d_lock);
 288                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 289                         spin_unlock(&dentry->d_lock);
 290                         return status;
 291                 } else if (status) {
 292                         /* Return a negative dentry, but leave it "pending" */
 293                         return status;
 294                 }
 295         /* Trigger mount for path component or follow link */
 296         } else if (flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY) ||
 297                         current->link_count) {
 298                 DPRINTK("waiting for mount name=%.*s",
 299                         dentry->d_name.len, dentry->d_name.name);
 300
 301                 spin_lock(&dentry->d_lock);
 302                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 303                 spin_unlock(&dentry->d_lock);
 304                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 305
 306                 DPRINTK("mount done status=%d", status);
 307
 308                 if (status) {
 309                         spin_lock(&dentry->d_lock);
 310                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 311                         spin_unlock(&dentry->d_lock);
 312                         return status;
 313                 }
 314         }
 315
 316         /* Initialize expiry counter after successful mount */
 317         if (ino)
 318                 ino->last_used = jiffies;
 319
 320         spin_lock(&dentry->d_lock);
 321         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 322         spin_unlock(&dentry->d_lock);
 323         return status;
 324 }
 325
 326 /* For autofs direct mounts the follow link triggers the mount */
 327 static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
 328 {
 329         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 330         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 331         int oz_mode = autofs4_oz_mode(sbi);
 332         unsigned int lookup_type;
 333         int status;
 334
 335         DPRINTK("dentry=%p %.*s oz_mode=%d nd->flags=%d",
 336                 dentry, dentry->d_name.len, dentry->d_name.name, oz_mode,
 337                 nd->flags);
 338
 339         /* If it's our master or we shouldn't trigger a mount we're done */
 340         lookup_type = nd->flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY);
 341         if (oz_mode || !lookup_type)
 342                 goto done;
 343
 344         /* If an expire request is pending wait for it. */
 345         if (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
 346                 DPRINTK("waiting for active request %p name=%.*s",
 347                         dentry, dentry->d_name.len, dentry->d_name.name);
 348
 349                 status = autofs4_wait(sbi, dentry, NFY_NONE);
 350
 351                 DPRINTK("request done status=%d", status);
 352         }
 353
 354         /*
 355          * If the dentry contains directories then it is an
 356          * autofs multi-mount with no root mount offset. So
 357          * don't try to mount it again.
 358          */
 359         spin_lock(&dcache_lock);
 360         if (!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {
 361                 spin_unlock(&dcache_lock);
 362
 363                 status = try_to_fill_dentry(dentry, 0);
 364                 if (status)
 365                         goto out_error;
 366
 367                 /*
 368                  * The mount succeeded but if there is no root mount
 369                  * it must be an autofs multi-mount with no root offset
 370                  * so we don't need to follow the mount.
 371                  */
 372                 if (d_mountpoint(dentry)) {
 373                         if (!autofs4_follow_mount(&nd->mnt, &nd->dentry)) {
 374                                 status = -ENOENT;
 375                                 goto out_error;
 376                         }
 377                 }
 378
 379                 goto done;
 380         }
 381         spin_unlock(&dcache_lock);
 382
 383 done:
 384         return NULL;
 385
 386 out_error:
 387         path_release(nd);
 388         return ERR_PTR(status);
 389 }
 390
 391 /*
 392  * Revalidate is called on every cache lookup.  Some of those
 393  * cache lookups may actually happen while the dentry is not
 394  * yet completely filled in, and revalidate has to delay such
 395  * lookups..
 396  */
 397 static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
 398 {
 399         struct inode *dir = dentry->d_parent->d_inode;
 400         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 401         int oz_mode = autofs4_oz_mode(sbi);
 402         int flags = nd ? nd->flags : 0;
 403         int status = 0;
 404
 405         /* Pending dentry */
 406         if (autofs4_ispending(dentry)) {
 407                 if (!oz_mode)
 408                         status = try_to_fill_dentry(dentry, flags);
 409                 return !status;
 410         }
 411
 412         /* Negative dentry.. invalidate if "old" */
 413         if (dentry->d_inode == NULL)
 414                 return 0;
 415
 416         /* Check for a non-mountpoint directory with no contents */
 417         spin_lock(&dcache_lock);
 418         if (S_ISDIR(dentry->d_inode->i_mode) &&
 419             !d_mountpoint(dentry) &&
 420             __simple_empty(dentry)) {
 421                 DPRINTK("dentry=%p %.*s, emptydir",
 422                          dentry, dentry->d_name.len, dentry->d_name.name);
 423                 spin_unlock(&dcache_lock);
 424                 if (!oz_mode)
 425                         status = try_to_fill_dentry(dentry, flags);
 426                 return !status;
 427         }
 428         spin_unlock(&dcache_lock);
 429
 430         return 1;
 431 }
 432
 433 void autofs4_dentry_release(struct dentry *de)
 434 {
 435         struct autofs_info *inf;
 436
 437         DPRINTK("releasing %p", de);
 438
 439         inf = autofs4_dentry_ino(de);
 440         de->d_fsdata = NULL;
 441
 442         if (inf) {
 443                 inf->dentry = NULL;
 444                 inf->inode = NULL;
 445
 446                 autofs4_free_ino(inf);
 447         }
 448 }
 449
 450 /* For dentries of directories in the root dir */
 451 static struct dentry_operations autofs4_root_dentry_operations = {
 452         .d_revalidate   = autofs4_revalidate,
 453         .d_release      = autofs4_dentry_release,
 454 };
 455
 456 /* For other dentries */
 457 static struct dentry_operations autofs4_dentry_operations = {
 458         .d_revalidate   = autofs4_revalidate,
 459         .d_release      = autofs4_dentry_release,
 460 };
 461
 462 /* Lookups in the root directory */
 463 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 464 {
 465         struct autofs_sb_info *sbi;
 466         int oz_mode;
 467
 468         DPRINTK("name = %.*s",
 469                 dentry->d_name.len, dentry->d_name.name);
 470
 471         /* File name too long to exist */
 472         if (dentry->d_name.len > NAME_MAX)
 473                 return ERR_PTR(-ENAMETOOLONG);
 474
 475         sbi = autofs4_sbi(dir->i_sb);
 476         oz_mode = autofs4_oz_mode(sbi);
 477
 478         DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
 479                  current->pid, process_group(current), sbi->catatonic, oz_mode);
 480
 481         /*
 482          * Mark the dentry incomplete, but add it. This is needed so
 483          * that the VFS layer knows about the dentry, and we can count
 484          * on catching any lookups through the revalidate.
 485          *
 486          * Let all the hard work be done by the revalidate function that
 487          * needs to be able to do this anyway..
 488          *
 489          * We need to do this before we release the directory semaphore.
 490          */
 491         dentry->d_op = &autofs4_root_dentry_operations;
 492
 493         if (!oz_mode) {
 494                 spin_lock(&dentry->d_lock);
 495                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 496                 spin_unlock(&dentry->d_lock);
 497         }
 498         dentry->d_fsdata = NULL;
 499         d_add(dentry, NULL);
 500
 501         if (dentry->d_op && dentry->d_op->d_revalidate) {
 502                 mutex_unlock(&dir->i_mutex);
 503                 (dentry->d_op->d_revalidate)(dentry, nd);
 504                 mutex_lock(&dir->i_mutex);
 505         }
 506
 507         /*
 508          * If we are still pending, check if we had to handle
 509          * a signal. If so we can force a restart..
 510          */
 511         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 512                 /* See if we were interrupted */
 513                 if (signal_pending(current)) {
 514                         sigset_t *sigset = &current->pending.signal;
 515                         if (sigismember (sigset, SIGKILL) ||
 516                             sigismember (sigset, SIGQUIT) ||
 517                             sigismember (sigset, SIGINT)) {
 518                             return ERR_PTR(-ERESTARTNOINTR);
 519                         }
 520                 }
 521         }
 522
 523         /*
 524          * If this dentry is unhashed, then we shouldn't honour this
 525          * lookup even if the dentry is positive.  Returning ENOENT here
 526          * doesn't do the right thing for all system calls, but it should
 527          * be OK for the operations we permit from an autofs.
 528          */
 529         if (dentry->d_inode && d_unhashed(dentry))
 530                 return ERR_PTR(-ENOENT);
 531
 532         return NULL;
 533 }
 534
 535 static int autofs4_dir_symlink(struct inode *dir,
 536                                struct dentry *dentry,
 537                                const char *symname)
 538 {
 539         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 540         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 541         struct autofs_info *p_ino;
 542         struct inode *inode;
 543         char *cp;
 544
 545         DPRINTK("%s <- %.*s", symname,
 546                 dentry->d_name.len, dentry->d_name.name);
 547
 548         if (!autofs4_oz_mode(sbi))
 549                 return -EACCES;
 550
 551         ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
 552         if (ino == NULL)
 553                 return -ENOSPC;
 554
 555         ino->size = strlen(symname);
 556         ino->u.symlink = cp = kmalloc(ino->size + 1, GFP_KERNEL);
 557
 558         if (cp == NULL) {
 559                 kfree(ino);
 560                 return -ENOSPC;
 561         }
 562
 563         strcpy(cp, symname);
 564
 565         inode = autofs4_get_inode(dir->i_sb, ino);
 566         d_instantiate(dentry, inode);
 567
 568         if (dir == dir->i_sb->s_root->d_inode)
 569                 dentry->d_op = &autofs4_root_dentry_operations;
 570         else
 571                 dentry->d_op = &autofs4_dentry_operations;
 572
 573         dentry->d_fsdata = ino;
 574         ino->dentry = dget(dentry);
 575         atomic_inc(&ino->count);
 576         p_ino = autofs4_dentry_ino(dentry->d_parent);
 577         if (p_ino && dentry->d_parent != dentry)
 578                 atomic_inc(&p_ino->count);
 579         ino->inode = inode;
 580
 581         dir->i_mtime = CURRENT_TIME;
 582
 583         return 0;
 584 }
 585
 586 /*
 587  * NOTE!
 588  *
 589  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 590  * that the file no longer exists. However, doing that means that the
 591  * VFS layer can turn the dentry into a negative dentry.  We don't want
 592  * this, because since the unlink is probably the result of an expire.
 593  * We simply d_drop it, which allows the dentry lookup to remount it
 594  * if necessary.
 595  *
 596  * If a process is blocked on the dentry waiting for the expire to finish,
 597  * it will invalidate the dentry and try to mount with a new one.
 598  *
 599  * Also see autofs4_dir_rmdir()..
 600  */
 601 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
 602 {
 603         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 604         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 605         struct autofs_info *p_ino;
 606
 607         /* This allows root to remove symlinks */
 608         if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
 609                 return -EACCES;
 610
 611         if (atomic_dec_and_test(&ino->count)) {
 612                 p_ino = autofs4_dentry_ino(dentry->d_parent);
 613                 if (p_ino && dentry->d_parent != dentry)
 614                         atomic_dec(&p_ino->count);
 615         }
 616         dput(ino->dentry);
 617
 618         dentry->d_inode->i_size = 0;
 619         dentry->d_inode->i_nlink = 0;
 620
 621         dir->i_mtime = CURRENT_TIME;
 622
 623         d_drop(dentry);
 624
 625         return 0;
 626 }
 627
 628 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
 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
 634         if (!autofs4_oz_mode(sbi))
 635                 return -EACCES;
 636
 637         spin_lock(&dcache_lock);
 638         if (!list_empty(&dentry->d_subdirs)) {
 639                 spin_unlock(&dcache_lock);
 640                 return -ENOTEMPTY;
 641         }
 642         spin_lock(&dentry->d_lock);
 643         __d_drop(dentry);
 644         spin_unlock(&dentry->d_lock);
 645         spin_unlock(&dcache_lock);
 646
 647         if (atomic_dec_and_test(&ino->count)) {
 648                 p_ino = autofs4_dentry_ino(dentry->d_parent);
 649                 if (p_ino && dentry->d_parent != dentry)
 650                         atomic_dec(&p_ino->count);
 651         }
 652         dput(ino->dentry);
 653         dentry->d_inode->i_size = 0;
 654         dentry->d_inode->i_nlink = 0;
 655
 656         if (dir->i_nlink)
 657                 dir->i_nlink--;
 658
 659         return 0;
 660 }
 661
 662 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 663 {
 664         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 665         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 666         struct autofs_info *p_ino;
 667         struct inode *inode;
 668
 669         if ( !autofs4_oz_mode(sbi) )
 670                 return -EACCES;
 671
 672         DPRINTK("dentry %p, creating %.*s",
 673                 dentry, dentry->d_name.len, dentry->d_name.name);
 674
 675         ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
 676         if (ino == NULL)
 677                 return -ENOSPC;
 678
 679         inode = autofs4_get_inode(dir->i_sb, ino);
 680         d_instantiate(dentry, inode);
 681
 682         if (dir == dir->i_sb->s_root->d_inode)
 683                 dentry->d_op = &autofs4_root_dentry_operations;
 684         else
 685                 dentry->d_op = &autofs4_dentry_operations;
 686
 687         dentry->d_fsdata = ino;
 688         ino->dentry = dget(dentry);
 689         atomic_inc(&ino->count);
 690         p_ino = autofs4_dentry_ino(dentry->d_parent);
 691         if (p_ino && dentry->d_parent != dentry)
 692                 atomic_inc(&p_ino->count);
 693         ino->inode = inode;
 694         dir->i_nlink++;
 695         dir->i_mtime = CURRENT_TIME;
 696
 697         return 0;
 698 }
 699
 700 /* Get/set timeout ioctl() operation */
 701 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
 702                                          unsigned long __user *p)
 703 {
 704         int rv;
 705         unsigned long ntimeout;
 706
 707         if ( (rv = get_user(ntimeout, p)) ||
 708              (rv = put_user(sbi->exp_timeout/HZ, p)) )
 709                 return rv;
 710
 711         if ( ntimeout > ULONG_MAX/HZ )
 712                 sbi->exp_timeout = 0;
 713         else
 714                 sbi->exp_timeout = ntimeout * HZ;
 715
 716         return 0;
 717 }
 718
 719 /* Return protocol version */
 720 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
 721 {
 722         return put_user(sbi->version, p);
 723 }
 724
 725 /* Return protocol sub version */
 726 static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
 727 {
 728         return put_user(sbi->sub_version, p);
 729 }
 730
 731 /*
 732  * Tells the daemon whether we need to reghost or not. Also, clears
 733  * the reghost_needed flag.
 734  */
 735 static inline int autofs4_ask_reghost(struct autofs_sb_info *sbi, int __user *p)
 736 {
 737         int status;
 738
 739         DPRINTK("returning %d", sbi->needs_reghost);
 740
 741         status = put_user(sbi->needs_reghost, p);
 742         if ( status )
 743                 return status;
 744
 745         sbi->needs_reghost = 0;
 746         return 0;
 747 }
 748
 749 /*
 750  * Enable / Disable reghosting ioctl() operation
 751  */
 752 static inline int autofs4_toggle_reghost(struct autofs_sb_info *sbi, int __user *p)
 753 {
 754         int status;
 755         int val;
 756
 757         status = get_user(val, p);
 758
 759         DPRINTK("reghost = %d", val);
 760
 761         if (status)
 762                 return status;
 763
 764         /* turn on/off reghosting, with the val */
 765         sbi->reghost_enabled = val;
 766         return 0;
 767 }
 768
 769 /*
 770 * Tells the daemon whether it can umount the autofs mount.
 771 */
 772 static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
 773 {
 774         int status = 0;
 775
 776         if (may_umount(mnt))
 777                 status = 1;
 778
 779         DPRINTK("returning %d", status);
 780
 781         status = put_user(status, p);
 782
 783         return status;
 784 }
 785
 786 /* Identify autofs4_dentries - this is so we can tell if there's
 787    an extra dentry refcount or not.  We only hold a refcount on the
 788    dentry if its non-negative (ie, d_inode != NULL)
 789 */
 790 int is_autofs4_dentry(struct dentry *dentry)
 791 {
 792         return dentry && dentry->d_inode &&
 793                 (dentry->d_op == &autofs4_root_dentry_operations ||
 794                  dentry->d_op == &autofs4_dentry_operations) &&
 795                 dentry->d_fsdata != NULL;
 796 }
 797
 798 /*
 799  * ioctl()'s on the root directory is the chief method for the daemon to
 800  * generate kernel reactions
 801  */
 802 static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
 803                              unsigned int cmd, unsigned long arg)
 804 {
 805         struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
 806         void __user *p = (void __user *)arg;
 807
 808         DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
 809                 cmd,arg,sbi,process_group(current));
 810
 811         if ( _IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
 812              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT )
 813                 return -ENOTTY;
 814
 815         if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
 816                 return -EPERM;
 817
 818         switch(cmd) {
 819         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
 820                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
 821         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
 822                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
 823         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
 824                 autofs4_catatonic_mode(sbi);
 825                 return 0;
 826         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
 827                 return autofs4_get_protover(sbi, p);
 828         case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
 829                 return autofs4_get_protosubver(sbi, p);
 830         case AUTOFS_IOC_SETTIMEOUT:
 831                 return autofs4_get_set_timeout(sbi, p);
 832
 833         case AUTOFS_IOC_TOGGLEREGHOST:
 834                 return autofs4_toggle_reghost(sbi, p);
 835         case AUTOFS_IOC_ASKREGHOST:
 836                 return autofs4_ask_reghost(sbi, p);
 837
 838         case AUTOFS_IOC_ASKUMOUNT:
 839                 return autofs4_ask_umount(filp->f_vfsmnt, p);
 840
 841         /* return a single thing to expire */
 842         case AUTOFS_IOC_EXPIRE:
 843                 return autofs4_expire_run(inode->i_sb,filp->f_vfsmnt,sbi, p);
 844         /* same as above, but can send multiple expires through pipe */
 845         case AUTOFS_IOC_EXPIRE_MULTI:
 846                 return autofs4_expire_multi(inode->i_sb,filp->f_vfsmnt,sbi, p);
 847
 848         default:
 849                 return -ENOSYS;
 850         }
 851 }