drivers/staging/autofs/root.c

   1 /* -*- linux-c -*- --------------------------------------------------------- *
   2  *
   3  * drivers/staging/autofs/root.c
   4  *
   5  *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
   6  *
   7  * This file is part of the Linux kernel and is made available under
   8  * the terms of the GNU General Public License, version 2, or at your
   9  * option, any later version, incorporated herein by reference.
  10  *
  11  * ------------------------------------------------------------------------- */
  12
  13 #include <linux/capability.h>
  14 #include <linux/errno.h>
  15 #include <linux/stat.h>
  16 #include <linux/slab.h>
  17 #include <linux/param.h>
  18 #include <linux/time.h>
  19 #include <linux/compat.h>
  20 #include <linux/smp_lock.h>
  21 #include "autofs_i.h"
  22
  23 static int autofs_root_readdir(struct file *,void *,filldir_t);
  24 static struct dentry *autofs_root_lookup(struct inode *,struct dentry *, struct nameidata *);
  25 static int autofs_root_symlink(struct inode *,struct dentry *,const char *);
  26 static int autofs_root_unlink(struct inode *,struct dentry *);
  27 static int autofs_root_rmdir(struct inode *,struct dentry *);
  28 static int autofs_root_mkdir(struct inode *,struct dentry *,int);
  29 static long autofs_root_ioctl(struct file *,unsigned int,unsigned long);
  30 #ifdef CONFIG_COMPAT
  31 static long autofs_root_compat_ioctl(struct file *,unsigned int,unsigned long);
  32 #endif
  33
  34 const struct file_operations autofs_root_operations = {
  35         .llseek         = generic_file_llseek,
  36         .read           = generic_read_dir,
  37         .readdir        = autofs_root_readdir,
  38         .unlocked_ioctl = autofs_root_ioctl,
  39 #ifdef CONFIG_COMPAT
  40         .compat_ioctl   = autofs_root_compat_ioctl,
  41 #endif
  42 };
  43
  44 const struct inode_operations autofs_root_inode_operations = {
  45         .lookup         = autofs_root_lookup,
  46         .unlink         = autofs_root_unlink,
  47         .symlink        = autofs_root_symlink,
  48         .mkdir          = autofs_root_mkdir,
  49         .rmdir          = autofs_root_rmdir,
  50 };
  51
  52 static int autofs_root_readdir(struct file *filp, void *dirent, filldir_t filldir)
  53 {
  54         struct autofs_dir_ent *ent = NULL;
  55         struct autofs_dirhash *dirhash;
  56         struct autofs_sb_info *sbi;
  57         struct inode * inode = filp->f_path.dentry->d_inode;
  58         off_t onr, nr;
  59
  60         lock_kernel();
  61
  62         sbi = autofs_sbi(inode->i_sb);
  63         dirhash = &sbi->dirhash;
  64         nr = filp->f_pos;
  65
  66         switch(nr)
  67         {
  68         case 0:
  69                 if (filldir(dirent, ".", 1, nr, inode->i_ino, DT_DIR) < 0)
  70                         goto out;
  71                 filp->f_pos = ++nr;
  72                 /* fall through */
  73         case 1:
  74                 if (filldir(dirent, "..", 2, nr, inode->i_ino, DT_DIR) < 0)
  75                         goto out;
  76                 filp->f_pos = ++nr;
  77                 /* fall through */
  78         default:
  79                 while (onr = nr, ent = autofs_hash_enum(dirhash,&nr,ent)) {
  80                         if (!ent->dentry || d_mountpoint(ent->dentry)) {
  81                                 if (filldir(dirent,ent->name,ent->len,onr,ent->ino,DT_UNKNOWN) < 0)
  82                                         goto out;
  83                                 filp->f_pos = nr;
  84                         }
  85                 }
  86                 break;
  87         }
  88
  89 out:
  90         unlock_kernel();
  91         return 0;
  92 }
  93
  94 static int try_to_fill_dentry(struct dentry *dentry, struct super_block *sb, struct autofs_sb_info *sbi)
  95 {
  96         struct inode * inode;
  97         struct autofs_dir_ent *ent;
  98         int status = 0;
  99
 100         if (!(ent = autofs_hash_lookup(&sbi->dirhash, &dentry->d_name))) {
 101                 do {
 102                         if (status && dentry->d_inode) {
 103                                 if (status != -ENOENT)
 104                                         printk("autofs warning: lookup failure on positive dentry, status = %d, name = %s\n", status, dentry->d_name.name);
 105                                 return 0; /* Try to get the kernel to invalidate this dentry */
 106                         }
 107
 108                         /* Turn this into a real negative dentry? */
 109                         if (status == -ENOENT) {
 110                                 dentry->d_time = jiffies + AUTOFS_NEGATIVE_TIMEOUT;
 111                                 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 112                                 return 1;
 113                         } else if (status) {
 114                                 /* Return a negative dentry, but leave it "pending" */
 115                                 return 1;
 116                         }
 117                         status = autofs_wait(sbi, &dentry->d_name);
 118                 } while (!(ent = autofs_hash_lookup(&sbi->dirhash, &dentry->d_name)));
 119         }
 120
 121         /* Abuse this field as a pointer to the directory entry, used to
 122            find the expire list pointers */
 123         dentry->d_time = (unsigned long) ent;
 124
 125         if (!dentry->d_inode) {
 126                 inode = autofs_iget(sb, ent->ino);
 127                 if (IS_ERR(inode)) {
 128                         /* Failed, but leave pending for next time */
 129                         return 1;
 130                 }
 131                 dentry->d_inode = inode;
 132         }
 133
 134         /* If this is a directory that isn't a mount point, bitch at the
 135            daemon and fix it in user space */
 136         if (S_ISDIR(dentry->d_inode->i_mode) && !d_mountpoint(dentry)) {
 137                 return !autofs_wait(sbi, &dentry->d_name);
 138         }
 139
 140         /* We don't update the usages for the autofs daemon itself, this
 141            is necessary for recursive autofs mounts */
 142         if (!autofs_oz_mode(sbi)) {
 143                 autofs_update_usage(&sbi->dirhash,ent);
 144         }
 145
 146         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 147         return 1;
 148 }
 149
 150
 151 /*
 152  * Revalidate is called on every cache lookup.  Some of those
 153  * cache lookups may actually happen while the dentry is not
 154  * yet completely filled in, and revalidate has to delay such
 155  * lookups..
 156  */
 157 static int autofs_revalidate(struct dentry *dentry, struct nameidata *nd)
 158 {
 159         struct inode * dir;
 160         struct autofs_sb_info *sbi;
 161         struct autofs_dir_ent *ent;
 162         int res;
 163
 164         if (nd->flags & LOOKUP_RCU)
 165                 return -ECHILD;
 166
 167         lock_kernel();
 168         dir = dentry->d_parent->d_inode;
 169         sbi = autofs_sbi(dir->i_sb);
 170
 171         /* Pending dentry */
 172         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 173                 if (autofs_oz_mode(sbi))
 174                         res = 1;
 175                 else
 176                         res = try_to_fill_dentry(dentry, dir->i_sb, sbi);
 177                 unlock_kernel();
 178                 return res;
 179         }
 180
 181         /* Negative dentry.. invalidate if "old" */
 182         if (!dentry->d_inode) {
 183                 unlock_kernel();
 184                 return (dentry->d_time - jiffies <= AUTOFS_NEGATIVE_TIMEOUT);
 185         }
 186
 187         /* Check for a non-mountpoint directory */
 188         if (S_ISDIR(dentry->d_inode->i_mode) && !d_mountpoint(dentry)) {
 189                 if (autofs_oz_mode(sbi))
 190                         res = 1;
 191                 else
 192                         res = try_to_fill_dentry(dentry, dir->i_sb, sbi);
 193                 unlock_kernel();
 194                 return res;
 195         }
 196
 197         /* Update the usage list */
 198         if (!autofs_oz_mode(sbi)) {
 199                 ent = (struct autofs_dir_ent *) dentry->d_time;
 200                 if (ent)
 201                         autofs_update_usage(&sbi->dirhash,ent);
 202         }
 203         unlock_kernel();
 204         return 1;
 205 }
 206
 207 static const struct dentry_operations autofs_dentry_operations = {
 208         .d_revalidate   = autofs_revalidate,
 209 };
 210
 211 static struct dentry *autofs_root_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 212 {
 213         struct autofs_sb_info *sbi;
 214         int oz_mode;
 215
 216         DPRINTK(("autofs_root_lookup: name = "));
 217         lock_kernel();
 218         autofs_say(dentry->d_name.name,dentry->d_name.len);
 219
 220         if (dentry->d_name.len > NAME_MAX) {
 221                 unlock_kernel();
 222                 return ERR_PTR(-ENAMETOOLONG);/* File name too long to exist */
 223         }
 224
 225         sbi = autofs_sbi(dir->i_sb);
 226
 227         oz_mode = autofs_oz_mode(sbi);
 228         DPRINTK(("autofs_lookup: pid = %u, pgrp = %u, catatonic = %d, "
 229                                 "oz_mode = %d\n", task_pid_nr(current),
 230                                 task_pgrp_nr(current), sbi->catatonic,
 231                                 oz_mode));
 232
 233         /*
 234          * Mark the dentry incomplete, but add it. This is needed so
 235          * that the VFS layer knows about the dentry, and we can count
 236          * on catching any lookups through the revalidate.
 237          *
 238          * Let all the hard work be done by the revalidate function that
 239          * needs to be able to do this anyway..
 240          *
 241          * We need to do this before we release the directory semaphore.
 242          */
 243         d_set_d_op(dentry, &autofs_dentry_operations);
 244         dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 245         d_add(dentry, NULL);
 246
 247         mutex_unlock(&dir->i_mutex);
 248         autofs_revalidate(dentry, nd);
 249         mutex_lock(&dir->i_mutex);
 250
 251         /*
 252          * If we are still pending, check if we had to handle
 253          * a signal. If so we can force a restart..
 254          */
 255         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 256                 /* See if we were interrupted */
 257                 if (signal_pending(current)) {
 258                         sigset_t *sigset = &current->pending.signal;
 259                         if (sigismember (sigset, SIGKILL) ||
 260                             sigismember (sigset, SIGQUIT) ||
 261                             sigismember (sigset, SIGINT)) {
 262                                 unlock_kernel();
 263                                 return ERR_PTR(-ERESTARTNOINTR);
 264                         }
 265                 }
 266         }
 267         unlock_kernel();
 268
 269         /*
 270          * If this dentry is unhashed, then we shouldn't honour this
 271          * lookup even if the dentry is positive.  Returning ENOENT here
 272          * doesn't do the right thing for all system calls, but it should
 273          * be OK for the operations we permit from an autofs.
 274          */
 275         if (dentry->d_inode && d_unhashed(dentry))
 276                 return ERR_PTR(-ENOENT);
 277
 278         return NULL;
 279 }
 280
 281 static int autofs_root_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
 282 {
 283         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 284         struct autofs_dirhash *dh = &sbi->dirhash;
 285         struct autofs_dir_ent *ent;
 286         unsigned int n;
 287         int slsize;
 288         struct autofs_symlink *sl;
 289         struct inode *inode;
 290
 291         DPRINTK(("autofs_root_symlink: %s <- ", symname));
 292         autofs_say(dentry->d_name.name,dentry->d_name.len);
 293
 294         lock_kernel();
 295         if (!autofs_oz_mode(sbi)) {
 296                 unlock_kernel();
 297                 return -EACCES;
 298         }
 299
 300         if (autofs_hash_lookup(dh, &dentry->d_name)) {
 301                 unlock_kernel();
 302                 return -EEXIST;
 303         }
 304
 305         n = find_first_zero_bit(sbi->symlink_bitmap,AUTOFS_MAX_SYMLINKS);
 306         if (n >= AUTOFS_MAX_SYMLINKS) {
 307                 unlock_kernel();
 308                 return -ENOSPC;
 309         }
 310
 311         set_bit(n,sbi->symlink_bitmap);
 312         sl = &sbi->symlink[n];
 313         sl->len = strlen(symname);
 314         sl->data = kmalloc(slsize = sl->len+1, GFP_KERNEL);
 315         if (!sl->data) {
 316                 clear_bit(n,sbi->symlink_bitmap);
 317                 unlock_kernel();
 318                 return -ENOSPC;
 319         }
 320
 321         ent = kmalloc(sizeof(struct autofs_dir_ent), GFP_KERNEL);
 322         if (!ent) {
 323                 kfree(sl->data);
 324                 clear_bit(n,sbi->symlink_bitmap);
 325                 unlock_kernel();
 326                 return -ENOSPC;
 327         }
 328
 329         ent->name = kmalloc(dentry->d_name.len+1, GFP_KERNEL);
 330         if (!ent->name) {
 331                 kfree(sl->data);
 332                 kfree(ent);
 333                 clear_bit(n,sbi->symlink_bitmap);
 334                 unlock_kernel();
 335                 return -ENOSPC;
 336         }
 337
 338         memcpy(sl->data,symname,slsize);
 339         sl->mtime = get_seconds();
 340
 341         ent->ino = AUTOFS_FIRST_SYMLINK + n;
 342         ent->hash = dentry->d_name.hash;
 343         memcpy(ent->name, dentry->d_name.name, 1+(ent->len = dentry->d_name.len));
 344         ent->dentry = NULL;     /* We don't keep the dentry for symlinks */
 345
 346         autofs_hash_insert(dh,ent);
 347
 348         inode = autofs_iget(dir->i_sb, ent->ino);
 349         if (IS_ERR(inode))
 350                 return PTR_ERR(inode);
 351
 352         d_instantiate(dentry, inode);
 353         unlock_kernel();
 354         return 0;
 355 }
 356
 357 /*
 358  * NOTE!
 359  *
 360  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 361  * that the file no longer exists. However, doing that means that the
 362  * VFS layer can turn the dentry into a negative dentry, which we
 363  * obviously do not want (we're dropping the entry not because it
 364  * doesn't exist, but because it has timed out).
 365  *
 366  * Also see autofs_root_rmdir()..
 367  */
 368 static int autofs_root_unlink(struct inode *dir, struct dentry *dentry)
 369 {
 370         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 371         struct autofs_dirhash *dh = &sbi->dirhash;
 372         struct autofs_dir_ent *ent;
 373         unsigned int n;
 374
 375         /* This allows root to remove symlinks */
 376         lock_kernel();
 377         if (!autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN)) {
 378                 unlock_kernel();
 379                 return -EACCES;
 380         }
 381
 382         ent = autofs_hash_lookup(dh, &dentry->d_name);
 383         if (!ent) {
 384                 unlock_kernel();
 385                 return -ENOENT;
 386         }
 387
 388         n = ent->ino - AUTOFS_FIRST_SYMLINK;
 389         if (n >= AUTOFS_MAX_SYMLINKS) {
 390                 unlock_kernel();
 391                 return -EISDIR; /* It's a directory, dummy */
 392         }
 393         if (!test_bit(n,sbi->symlink_bitmap)) {
 394                 unlock_kernel();
 395                 return -EINVAL; /* Nonexistent symlink?  Shouldn't happen */
 396         }
 397
 398         dentry->d_time = (unsigned long)(struct autofs_dirhash *)NULL;
 399         autofs_hash_delete(ent);
 400         clear_bit(n,sbi->symlink_bitmap);
 401         kfree(sbi->symlink[n].data);
 402         d_drop(dentry);
 403
 404         unlock_kernel();
 405         return 0;
 406 }
 407
 408 static int autofs_root_rmdir(struct inode *dir, struct dentry *dentry)
 409 {
 410         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 411         struct autofs_dirhash *dh = &sbi->dirhash;
 412         struct autofs_dir_ent *ent;
 413
 414         lock_kernel();
 415         if (!autofs_oz_mode(sbi)) {
 416                 unlock_kernel();
 417                 return -EACCES;
 418         }
 419
 420         ent = autofs_hash_lookup(dh, &dentry->d_name);
 421         if (!ent) {
 422                 unlock_kernel();
 423                 return -ENOENT;
 424         }
 425
 426         if ((unsigned int)ent->ino < AUTOFS_FIRST_DIR_INO) {
 427                 unlock_kernel();
 428                 return -ENOTDIR; /* Not a directory */
 429         }
 430
 431         if (ent->dentry != dentry) {
 432                 printk("autofs_rmdir: odentry != dentry for entry %s\n", dentry->d_name.name);
 433         }
 434
 435         dentry->d_time = (unsigned long)(struct autofs_dir_ent *)NULL;
 436         autofs_hash_delete(ent);
 437         drop_nlink(dir);
 438         d_drop(dentry);
 439         unlock_kernel();
 440
 441         return 0;
 442 }
 443
 444 static int autofs_root_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 445 {
 446         struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
 447         struct autofs_dirhash *dh = &sbi->dirhash;
 448         struct autofs_dir_ent *ent;
 449         struct inode *inode;
 450         ino_t ino;
 451
 452         lock_kernel();
 453         if (!autofs_oz_mode(sbi)) {
 454                 unlock_kernel();
 455                 return -EACCES;
 456         }
 457
 458         ent = autofs_hash_lookup(dh, &dentry->d_name);
 459         if (ent) {
 460                 unlock_kernel();
 461                 return -EEXIST;
 462         }
 463
 464         if (sbi->next_dir_ino < AUTOFS_FIRST_DIR_INO) {
 465                 printk("autofs: Out of inode numbers -- what the heck did you do??\n");
 466                 unlock_kernel();
 467                 return -ENOSPC;
 468         }
 469         ino = sbi->next_dir_ino++;
 470
 471         ent = kmalloc(sizeof(struct autofs_dir_ent), GFP_KERNEL);
 472         if (!ent) {
 473                 unlock_kernel();
 474                 return -ENOSPC;
 475         }
 476
 477         ent->name = kmalloc(dentry->d_name.len+1, GFP_KERNEL);
 478         if (!ent->name) {
 479                 kfree(ent);
 480                 unlock_kernel();
 481                 return -ENOSPC;
 482         }
 483
 484         ent->hash = dentry->d_name.hash;
 485         memcpy(ent->name, dentry->d_name.name, 1+(ent->len = dentry->d_name.len));
 486         ent->ino = ino;
 487         ent->dentry = dentry;
 488         autofs_hash_insert(dh,ent);
 489
 490         inc_nlink(dir);
 491
 492         inode = autofs_iget(dir->i_sb, ino);
 493         if (IS_ERR(inode)) {
 494                 drop_nlink(dir);
 495                 return PTR_ERR(inode);
 496         }
 497
 498         d_instantiate(dentry, inode);
 499         unlock_kernel();
 500
 501         return 0;
 502 }
 503
 504 /* Get/set timeout ioctl() operation */
 505 #ifdef CONFIG_COMPAT
 506 static inline int autofs_compat_get_set_timeout(struct autofs_sb_info *sbi,
 507                                          unsigned int __user *p)
 508 {
 509         unsigned long ntimeout;
 510
 511         if (get_user(ntimeout, p) ||
 512             put_user(sbi->exp_timeout / HZ, p))
 513                 return -EFAULT;
 514
 515         if (ntimeout > UINT_MAX/HZ)
 516                 sbi->exp_timeout = 0;
 517         else
 518                 sbi->exp_timeout = ntimeout * HZ;
 519
 520         return 0;
 521 }
 522 #endif
 523
 524 static inline int autofs_get_set_timeout(struct autofs_sb_info *sbi,
 525                                          unsigned long __user *p)
 526 {
 527         unsigned long ntimeout;
 528
 529         if (get_user(ntimeout, p) ||
 530             put_user(sbi->exp_timeout / HZ, p))
 531                 return -EFAULT;
 532
 533         if (ntimeout > ULONG_MAX/HZ)
 534                 sbi->exp_timeout = 0;
 535         else
 536                 sbi->exp_timeout = ntimeout * HZ;
 537
 538         return 0;
 539 }
 540
 541 /* Return protocol version */
 542 static inline int autofs_get_protover(int __user *p)
 543 {
 544         return put_user(AUTOFS_PROTO_VERSION, p);
 545 }
 546
 547 /* Perform an expiry operation */
 548 static inline int autofs_expire_run(struct super_block *sb,
 549                                     struct autofs_sb_info *sbi,
 550                                     struct vfsmount *mnt,
 551                                     struct autofs_packet_expire __user *pkt_p)
 552 {
 553         struct autofs_dir_ent *ent;
 554         struct autofs_packet_expire pkt;
 555
 556         memset(&pkt,0,sizeof pkt);
 557
 558         pkt.hdr.proto_version = AUTOFS_PROTO_VERSION;
 559         pkt.hdr.type = autofs_ptype_expire;
 560
 561         if (!sbi->exp_timeout || !(ent = autofs_expire(sb,sbi,mnt)))
 562                 return -EAGAIN;
 563
 564         pkt.len = ent->len;
 565         memcpy(pkt.name, ent->name, pkt.len);
 566         pkt.name[pkt.len] = '\0';
 567
 568         if (copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)))
 569                 return -EFAULT;
 570
 571         return 0;
 572 }
 573
 574 /*
 575  * ioctl()'s on the root directory is the chief method for the daemon to
 576  * generate kernel reactions
 577  */
 578 static int autofs_do_root_ioctl(struct inode *inode, struct file *filp,
 579                              unsigned int cmd, unsigned long arg)
 580 {
 581         struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb);
 582         void __user *argp = (void __user *)arg;
 583
 584         DPRINTK(("autofs_ioctl: cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",cmd,arg,sbi,task_pgrp_nr(current)));
 585
 586         if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
 587              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
 588                 return -ENOTTY;
 589
 590         if (!autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
 591                 return -EPERM;
 592
 593         switch(cmd) {
 594         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
 595                 return autofs_wait_release(sbi,(autofs_wqt_t)arg,0);
 596         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
 597                 return autofs_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
 598         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
 599                 autofs_catatonic_mode(sbi);
 600                 return 0;
 601         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
 602                 return autofs_get_protover(argp);
 603 #ifdef CONFIG_COMPAT
 604         case AUTOFS_IOC_SETTIMEOUT32:
 605                 return autofs_compat_get_set_timeout(sbi, argp);
 606 #endif
 607         case AUTOFS_IOC_SETTIMEOUT:
 608                 return autofs_get_set_timeout(sbi, argp);
 609         case AUTOFS_IOC_EXPIRE:
 610                 return autofs_expire_run(inode->i_sb, sbi, filp->f_path.mnt,
 611                                          argp);
 612         default:
 613                 return -ENOSYS;
 614         }
 615
 616 }
 617
 618 static long autofs_root_ioctl(struct file *filp,
 619                              unsigned int cmd, unsigned long arg)
 620 {
 621         int ret;
 622
 623         lock_kernel();
 624         ret = autofs_do_root_ioctl(filp->f_path.dentry->d_inode,
 625                                    filp, cmd, arg);
 626         unlock_kernel();
 627
 628         return ret;
 629 }
 630
 631 #ifdef CONFIG_COMPAT
 632 static long autofs_root_compat_ioctl(struct file *filp,
 633                              unsigned int cmd, unsigned long arg)
 634 {
 635         struct inode *inode = filp->f_path.dentry->d_inode;
 636         int ret;
 637
 638         lock_kernel();
 639         if (cmd == AUTOFS_IOC_READY || cmd == AUTOFS_IOC_FAIL)
 640                 ret = autofs_do_root_ioctl(inode, filp, cmd, arg);
 641         else
 642                 ret = autofs_do_root_ioctl(inode, filp, cmd,
 643                         (unsigned long)compat_ptr(arg));
 644         unlock_kernel();
 645
 646         return ret;
 647 }
 648 #endif