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 "autofs_i.h"
  21
  22 static int autofs4_dir_symlink(struct inode *,struct dentry *,const char *);
  23 static int autofs4_dir_unlink(struct inode *,struct dentry *);
  24 static int autofs4_dir_rmdir(struct inode *,struct dentry *);
  25 static int autofs4_dir_mkdir(struct inode *,struct dentry *,int);
  26 static int autofs4_root_ioctl(struct inode *, struct file *,unsigned int,unsigned long);
  27 static int autofs4_dir_open(struct inode *inode, struct file *file);
  28 static struct dentry *autofs4_lookup(struct inode *,struct dentry *, struct nameidata *);
  29 static void *autofs4_follow_link(struct dentry *, struct nameidata *);
  30
  31 #define TRIGGER_FLAGS   (LOOKUP_CONTINUE | LOOKUP_DIRECTORY)
  32 #define TRIGGER_INTENTS (LOOKUP_OPEN | LOOKUP_CREATE)
  33
  34 const struct file_operations autofs4_root_operations = {
  35         .open           = dcache_dir_open,
  36         .release        = dcache_dir_close,
  37         .read           = generic_read_dir,
  38         .readdir        = dcache_readdir,
  39         .llseek         = dcache_dir_lseek,
  40         .ioctl          = autofs4_root_ioctl,
  41 };
  42
  43 const struct file_operations autofs4_dir_operations = {
  44         .open           = autofs4_dir_open,
  45         .release        = dcache_dir_close,
  46         .read           = generic_read_dir,
  47         .readdir        = dcache_readdir,
  48         .llseek         = dcache_dir_lseek,
  49 };
  50
  51 const struct inode_operations autofs4_indirect_root_inode_operations = {
  52         .lookup         = autofs4_lookup,
  53         .unlink         = autofs4_dir_unlink,
  54         .symlink        = autofs4_dir_symlink,
  55         .mkdir          = autofs4_dir_mkdir,
  56         .rmdir          = autofs4_dir_rmdir,
  57 };
  58
  59 const struct inode_operations autofs4_direct_root_inode_operations = {
  60         .lookup         = autofs4_lookup,
  61         .unlink         = autofs4_dir_unlink,
  62         .mkdir          = autofs4_dir_mkdir,
  63         .rmdir          = autofs4_dir_rmdir,
  64         .follow_link    = autofs4_follow_link,
  65 };
  66
  67 const struct inode_operations autofs4_dir_inode_operations = {
  68         .lookup         = autofs4_lookup,
  69         .unlink         = autofs4_dir_unlink,
  70         .symlink        = autofs4_dir_symlink,
  71         .mkdir          = autofs4_dir_mkdir,
  72         .rmdir          = autofs4_dir_rmdir,
  73 };
  74
  75 static int autofs4_dir_open(struct inode *inode, struct file *file)
  76 {
  77         struct dentry *dentry = file->f_path.dentry;
  78         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
  79
  80         DPRINTK("file=%p dentry=%p %.*s",
  81                 file, dentry, dentry->d_name.len, dentry->d_name.name);
  82
  83         if (autofs4_oz_mode(sbi))
  84                 goto out;
  85
  86         /*
  87          * An empty directory in an autofs file system is always a
  88          * mount point. The daemon must have failed to mount this
  89          * during lookup so it doesn't exist. This can happen, for
  90          * example, if user space returns an incorrect status for a
  91          * mount request. Otherwise we're doing a readdir on the
  92          * autofs file system so just let the libfs routines handle
  93          * it.
  94          */
  95         spin_lock(&dcache_lock);
  96         if (!d_mountpoint(dentry) && __simple_empty(dentry)) {
  97                 spin_unlock(&dcache_lock);
  98                 return -ENOENT;
  99         }
 100         spin_unlock(&dcache_lock);
 101
 102 out:
 103         return dcache_dir_open(inode, file);
 104 }
 105
 106 static int try_to_fill_dentry(struct dentry *dentry, int flags)
 107 {
 108         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 109         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 110         int status;
 111
 112         DPRINTK("dentry=%p %.*s ino=%p",
 113                  dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode);
 114
 115         /*
 116          * Wait for a pending mount, triggering one if there
 117          * isn't one already
 118          */
 119         if (dentry->d_inode == NULL) {
 120                 DPRINTK("waiting for mount name=%.*s",
 121                          dentry->d_name.len, dentry->d_name.name);
 122
 123                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 124
 125                 DPRINTK("mount done status=%d", status);
 126
 127                 /* Turn this into a real negative dentry? */
 128                 if (status == -ENOENT) {
 129                         spin_lock(&dentry->d_lock);
 130                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 131                         spin_unlock(&dentry->d_lock);
 132                         return status;
 133                 } else if (status) {
 134                         /* Return a negative dentry, but leave it "pending" */
 135                         return status;
 136                 }
 137         /* Trigger mount for path component or follow link */
 138         } else if (dentry->d_flags & DCACHE_AUTOFS_PENDING ||
 139                         flags & (TRIGGER_FLAGS | TRIGGER_INTENTS) ||
 140                         current->link_count) {
 141                 DPRINTK("waiting for mount name=%.*s",
 142                         dentry->d_name.len, dentry->d_name.name);
 143
 144                 spin_lock(&dentry->d_lock);
 145                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 146                 spin_unlock(&dentry->d_lock);
 147                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 148
 149                 DPRINTK("mount done status=%d", status);
 150
 151                 if (status) {
 152                         spin_lock(&dentry->d_lock);
 153                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 154                         spin_unlock(&dentry->d_lock);
 155                         return status;
 156                 }
 157         }
 158
 159         /* Initialize expiry counter after successful mount */
 160         if (ino)
 161                 ino->last_used = jiffies;
 162
 163         spin_lock(&dentry->d_lock);
 164         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 165         spin_unlock(&dentry->d_lock);
 166
 167         return 0;
 168 }
 169
 170 /* For autofs direct mounts the follow link triggers the mount */
 171 static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
 172 {
 173         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 174         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 175         int oz_mode = autofs4_oz_mode(sbi);
 176         unsigned int lookup_type;
 177         int status;
 178
 179         DPRINTK("dentry=%p %.*s oz_mode=%d nd->flags=%d",
 180                 dentry, dentry->d_name.len, dentry->d_name.name, oz_mode,
 181                 nd->flags);
 182         /*
 183          * For an expire of a covered direct or offset mount we need
 184          * to break out of follow_down() at the autofs mount trigger
 185          * (d_mounted--), so we can see the expiring flag, and manage
 186          * the blocking and following here until the expire is completed.
 187          */
 188         if (oz_mode) {
 189                 spin_lock(&sbi->fs_lock);
 190                 if (ino->flags & AUTOFS_INF_EXPIRING) {
 191                         spin_unlock(&sbi->fs_lock);
 192                         /* Follow down to our covering mount. */
 193                         if (!follow_down(&nd->path))
 194                                 goto done;
 195                         goto follow;
 196                 }
 197                 spin_unlock(&sbi->fs_lock);
 198                 goto done;
 199         }
 200
 201         /* If an expire request is pending everyone must wait. */
 202         autofs4_expire_wait(dentry);
 203
 204         /* We trigger a mount for almost all flags */
 205         lookup_type = nd->flags & (TRIGGER_FLAGS | TRIGGER_INTENTS);
 206         if (!(lookup_type || dentry->d_flags & DCACHE_AUTOFS_PENDING))
 207                 goto follow;
 208
 209         /*
 210          * If the dentry contains directories then it is an autofs
 211          * multi-mount with no root mount offset. So don't try to
 212          * mount it again.
 213          */
 214         spin_lock(&dcache_lock);
 215         if (dentry->d_flags & DCACHE_AUTOFS_PENDING ||
 216             (!d_mountpoint(dentry) && __simple_empty(dentry))) {
 217                 spin_unlock(&dcache_lock);
 218
 219                 status = try_to_fill_dentry(dentry, 0);
 220                 if (status)
 221                         goto out_error;
 222
 223                 goto follow;
 224         }
 225         spin_unlock(&dcache_lock);
 226 follow:
 227         /*
 228          * If there is no root mount it must be an autofs
 229          * multi-mount with no root offset so we don't need
 230          * to follow it.
 231          */
 232         if (d_mountpoint(dentry)) {
 233                 if (!autofs4_follow_mount(&nd->path)) {
 234                         status = -ENOENT;
 235                         goto out_error;
 236                 }
 237         }
 238
 239 done:
 240         return NULL;
 241
 242 out_error:
 243         path_put(&nd->path);
 244         return ERR_PTR(status);
 245 }
 246
 247 /*
 248  * Revalidate is called on every cache lookup.  Some of those
 249  * cache lookups may actually happen while the dentry is not
 250  * yet completely filled in, and revalidate has to delay such
 251  * lookups..
 252  */
 253 static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
 254 {
 255         struct inode *dir = dentry->d_parent->d_inode;
 256         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 257         int oz_mode = autofs4_oz_mode(sbi);
 258         int flags = nd ? nd->flags : 0;
 259         int status = 1;
 260
 261         /* Pending dentry */
 262         spin_lock(&sbi->fs_lock);
 263         if (autofs4_ispending(dentry)) {
 264                 /* The daemon never causes a mount to trigger */
 265                 spin_unlock(&sbi->fs_lock);
 266
 267                 if (oz_mode)
 268                         return 1;
 269
 270                 /*
 271                  * If the directory has gone away due to an expire
 272                  * we have been called as ->d_revalidate() and so
 273                  * we need to return false and proceed to ->lookup().
 274                  */
 275                 if (autofs4_expire_wait(dentry) == -EAGAIN)
 276                         return 0;
 277
 278                 /*
 279                  * A zero status is success otherwise we have a
 280                  * negative error code.
 281                  */
 282                 status = try_to_fill_dentry(dentry, flags);
 283                 if (status == 0)
 284                         return 1;
 285
 286                 return status;
 287         }
 288         spin_unlock(&sbi->fs_lock);
 289
 290         /* Negative dentry.. invalidate if "old" */
 291         if (dentry->d_inode == NULL)
 292                 return 0;
 293
 294         /* Check for a non-mountpoint directory with no contents */
 295         spin_lock(&dcache_lock);
 296         if (S_ISDIR(dentry->d_inode->i_mode) &&
 297             !d_mountpoint(dentry) &&
 298             __simple_empty(dentry)) {
 299                 DPRINTK("dentry=%p %.*s, emptydir",
 300                          dentry, dentry->d_name.len, dentry->d_name.name);
 301                 spin_unlock(&dcache_lock);
 302
 303                 /* The daemon never causes a mount to trigger */
 304                 if (oz_mode)
 305                         return 1;
 306
 307                 /*
 308                  * A zero status is success otherwise we have a
 309                  * negative error code.
 310                  */
 311                 status = try_to_fill_dentry(dentry, flags);
 312                 if (status == 0)
 313                         return 1;
 314
 315                 return status;
 316         }
 317         spin_unlock(&dcache_lock);
 318
 319         return 1;
 320 }
 321
 322 void autofs4_dentry_release(struct dentry *de)
 323 {
 324         struct autofs_info *inf;
 325
 326         DPRINTK("releasing %p", de);
 327
 328         inf = autofs4_dentry_ino(de);
 329         de->d_fsdata = NULL;
 330
 331         if (inf) {
 332                 struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb);
 333
 334                 if (sbi) {
 335                         spin_lock(&sbi->lookup_lock);
 336                         if (!list_empty(&inf->active))
 337                                 list_del(&inf->active);
 338                         if (!list_empty(&inf->expiring))
 339                                 list_del(&inf->expiring);
 340                         spin_unlock(&sbi->lookup_lock);
 341                 }
 342
 343                 inf->dentry = NULL;
 344                 inf->inode = NULL;
 345
 346                 autofs4_free_ino(inf);
 347         }
 348 }
 349
 350 /* For dentries of directories in the root dir */
 351 static const struct dentry_operations autofs4_root_dentry_operations = {
 352         .d_revalidate   = autofs4_revalidate,
 353         .d_release      = autofs4_dentry_release,
 354 };
 355
 356 /* For other dentries */
 357 static const struct dentry_operations autofs4_dentry_operations = {
 358         .d_revalidate   = autofs4_revalidate,
 359         .d_release      = autofs4_dentry_release,
 360 };
 361
 362 static struct dentry *autofs4_lookup_active(struct autofs_sb_info *sbi, struct dentry *parent, struct qstr *name)
 363 {
 364         unsigned int len = name->len;
 365         unsigned int hash = name->hash;
 366         const unsigned char *str = name->name;
 367         struct list_head *p, *head;
 368
 369         spin_lock(&dcache_lock);
 370         spin_lock(&sbi->lookup_lock);
 371         head = &sbi->active_list;
 372         list_for_each(p, head) {
 373                 struct autofs_info *ino;
 374                 struct dentry *dentry;
 375                 struct qstr *qstr;
 376
 377                 ino = list_entry(p, struct autofs_info, active);
 378                 dentry = ino->dentry;
 379
 380                 spin_lock(&dentry->d_lock);
 381
 382                 /* Already gone? */
 383                 if (atomic_read(&dentry->d_count) == 0)
 384                         goto next;
 385
 386                 qstr = &dentry->d_name;
 387
 388                 if (dentry->d_name.hash != hash)
 389                         goto next;
 390                 if (dentry->d_parent != parent)
 391                         goto next;
 392
 393                 if (qstr->len != len)
 394                         goto next;
 395                 if (memcmp(qstr->name, str, len))
 396                         goto next;
 397
 398                 if (d_unhashed(dentry)) {
 399                         dget(dentry);
 400                         spin_unlock(&dentry->d_lock);
 401                         spin_unlock(&sbi->lookup_lock);
 402                         spin_unlock(&dcache_lock);
 403                         return dentry;
 404                 }
 405 next:
 406                 spin_unlock(&dentry->d_lock);
 407         }
 408         spin_unlock(&sbi->lookup_lock);
 409         spin_unlock(&dcache_lock);
 410
 411         return NULL;
 412 }
 413
 414 static struct dentry *autofs4_lookup_expiring(struct autofs_sb_info *sbi, struct dentry *parent, struct qstr *name)
 415 {
 416         unsigned int len = name->len;
 417         unsigned int hash = name->hash;
 418         const unsigned char *str = name->name;
 419         struct list_head *p, *head;
 420
 421         spin_lock(&dcache_lock);
 422         spin_lock(&sbi->lookup_lock);
 423         head = &sbi->expiring_list;
 424         list_for_each(p, head) {
 425                 struct autofs_info *ino;
 426                 struct dentry *dentry;
 427                 struct qstr *qstr;
 428
 429                 ino = list_entry(p, struct autofs_info, expiring);
 430                 dentry = ino->dentry;
 431
 432                 spin_lock(&dentry->d_lock);
 433
 434                 /* Bad luck, we've already been dentry_iput */
 435                 if (!dentry->d_inode)
 436                         goto next;
 437
 438                 qstr = &dentry->d_name;
 439
 440                 if (dentry->d_name.hash != hash)
 441                         goto next;
 442                 if (dentry->d_parent != parent)
 443                         goto next;
 444
 445                 if (qstr->len != len)
 446                         goto next;
 447                 if (memcmp(qstr->name, str, len))
 448                         goto next;
 449
 450                 if (d_unhashed(dentry)) {
 451                         dget(dentry);
 452                         spin_unlock(&dentry->d_lock);
 453                         spin_unlock(&sbi->lookup_lock);
 454                         spin_unlock(&dcache_lock);
 455                         return dentry;
 456                 }
 457 next:
 458                 spin_unlock(&dentry->d_lock);
 459         }
 460         spin_unlock(&sbi->lookup_lock);
 461         spin_unlock(&dcache_lock);
 462
 463         return NULL;
 464 }
 465
 466 /* Lookups in the root directory */
 467 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 468 {
 469         struct autofs_sb_info *sbi;
 470         struct autofs_info *ino;
 471         struct dentry *expiring, *unhashed;
 472         int oz_mode;
 473
 474         DPRINTK("name = %.*s",
 475                 dentry->d_name.len, dentry->d_name.name);
 476
 477         /* File name too long to exist */
 478         if (dentry->d_name.len > NAME_MAX)
 479                 return ERR_PTR(-ENAMETOOLONG);
 480
 481         sbi = autofs4_sbi(dir->i_sb);
 482         oz_mode = autofs4_oz_mode(sbi);
 483
 484         DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
 485                  current->pid, task_pgrp_nr(current), sbi->catatonic, oz_mode);
 486
 487         unhashed = autofs4_lookup_active(sbi, dentry->d_parent, &dentry->d_name);
 488         if (unhashed)
 489                 dentry = unhashed;
 490         else {
 491                 /*
 492                  * Mark the dentry incomplete but don't hash it. We do this
 493                  * to serialize our inode creation operations (symlink and
 494                  * mkdir) which prevents deadlock during the callback to
 495                  * the daemon. Subsequent user space lookups for the same
 496                  * dentry are placed on the wait queue while the daemon
 497                  * itself is allowed passage unresticted so the create
 498                  * operation itself can then hash the dentry. Finally,
 499                  * we check for the hashed dentry and return the newly
 500                  * hashed dentry.
 501                  */
 502                 dentry->d_op = &autofs4_root_dentry_operations;
 503
 504                 /*
 505                  * And we need to ensure that the same dentry is used for
 506                  * all following lookup calls until it is hashed so that
 507                  * the dentry flags are persistent throughout the request.
 508                  */
 509                 ino = autofs4_init_ino(NULL, sbi, 0555);
 510                 if (!ino)
 511                         return ERR_PTR(-ENOMEM);
 512
 513                 dentry->d_fsdata = ino;
 514                 ino->dentry = dentry;
 515
 516                 spin_lock(&sbi->lookup_lock);
 517                 list_add(&ino->active, &sbi->active_list);
 518                 spin_unlock(&sbi->lookup_lock);
 519
 520                 d_instantiate(dentry, NULL);
 521         }
 522
 523         if (!oz_mode) {
 524                 mutex_unlock(&dir->i_mutex);
 525                 expiring = autofs4_lookup_expiring(sbi,
 526                                                    dentry->d_parent,
 527                                                    &dentry->d_name);
 528                 if (expiring) {
 529                         /*
 530                          * If we are racing with expire the request might not
 531                          * be quite complete but the directory has been removed
 532                          * so it must have been successful, so just wait for it.
 533                          */
 534                         ino = autofs4_dentry_ino(expiring);
 535                         autofs4_expire_wait(expiring);
 536                         spin_lock(&sbi->lookup_lock);
 537                         if (!list_empty(&ino->expiring))
 538                                 list_del_init(&ino->expiring);
 539                         spin_unlock(&sbi->lookup_lock);
 540                         dput(expiring);
 541                 }
 542
 543                 spin_lock(&dentry->d_lock);
 544                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 545                 spin_unlock(&dentry->d_lock);
 546                 if (dentry->d_op && dentry->d_op->d_revalidate)
 547                         (dentry->d_op->d_revalidate)(dentry, nd);
 548                 mutex_lock(&dir->i_mutex);
 549         }
 550
 551         /*
 552          * If we are still pending, check if we had to handle
 553          * a signal. If so we can force a restart..
 554          */
 555         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 556                 /* See if we were interrupted */
 557                 if (signal_pending(current)) {
 558                         sigset_t *sigset = &current->pending.signal;
 559                         if (sigismember (sigset, SIGKILL) ||
 560                             sigismember (sigset, SIGQUIT) ||
 561                             sigismember (sigset, SIGINT)) {
 562                             if (unhashed)
 563                                 dput(unhashed);
 564                             return ERR_PTR(-ERESTARTNOINTR);
 565                         }
 566                 }
 567                 if (!oz_mode) {
 568                         spin_lock(&dentry->d_lock);
 569                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 570                         spin_unlock(&dentry->d_lock);
 571                 }
 572         }
 573
 574         /*
 575          * If this dentry is unhashed, then we shouldn't honour this
 576          * lookup.  Returning ENOENT here doesn't do the right thing
 577          * for all system calls, but it should be OK for the operations
 578          * we permit from an autofs.
 579          */
 580         if (!oz_mode && d_unhashed(dentry)) {
 581                 /*
 582                  * A user space application can (and has done in the past)
 583                  * remove and re-create this directory during the callback.
 584                  * This can leave us with an unhashed dentry, but a
 585                  * successful mount!  So we need to perform another
 586                  * cached lookup in case the dentry now exists.
 587                  */
 588                 struct dentry *parent = dentry->d_parent;
 589                 struct dentry *new = d_lookup(parent, &dentry->d_name);
 590                 if (new != NULL)
 591                         dentry = new;
 592                 else
 593                         dentry = ERR_PTR(-ENOENT);
 594
 595                 if (unhashed)
 596                         dput(unhashed);
 597
 598                 return dentry;
 599         }
 600
 601         if (unhashed)
 602                 return unhashed;
 603
 604         return NULL;
 605 }
 606
 607 static int autofs4_dir_symlink(struct inode *dir,
 608                                struct dentry *dentry,
 609                                const char *symname)
 610 {
 611         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 612         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 613         struct autofs_info *p_ino;
 614         struct inode *inode;
 615         char *cp;
 616
 617         DPRINTK("%s <- %.*s", symname,
 618                 dentry->d_name.len, dentry->d_name.name);
 619
 620         if (!autofs4_oz_mode(sbi))
 621                 return -EACCES;
 622
 623         ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
 624         if (!ino)
 625                 return -ENOMEM;
 626
 627         spin_lock(&sbi->lookup_lock);
 628         if (!list_empty(&ino->active))
 629                 list_del_init(&ino->active);
 630         spin_unlock(&sbi->lookup_lock);
 631
 632         ino->size = strlen(symname);
 633         cp = kmalloc(ino->size + 1, GFP_KERNEL);
 634         if (!cp) {
 635                 if (!dentry->d_fsdata)
 636                         kfree(ino);
 637                 return -ENOMEM;
 638         }
 639
 640         strcpy(cp, symname);
 641
 642         inode = autofs4_get_inode(dir->i_sb, ino);
 643         if (!inode) {
 644                 kfree(cp);
 645                 if (!dentry->d_fsdata)
 646                         kfree(ino);
 647                 return -ENOMEM;
 648         }
 649         d_add(dentry, inode);
 650
 651         if (dir == dir->i_sb->s_root->d_inode)
 652                 dentry->d_op = &autofs4_root_dentry_operations;
 653         else
 654                 dentry->d_op = &autofs4_dentry_operations;
 655
 656         dentry->d_fsdata = ino;
 657         ino->dentry = dget(dentry);
 658         atomic_inc(&ino->count);
 659         p_ino = autofs4_dentry_ino(dentry->d_parent);
 660         if (p_ino && dentry->d_parent != dentry)
 661                 atomic_inc(&p_ino->count);
 662         ino->inode = inode;
 663
 664         ino->u.symlink = cp;
 665         dir->i_mtime = CURRENT_TIME;
 666
 667         return 0;
 668 }
 669
 670 /*
 671  * NOTE!
 672  *
 673  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 674  * that the file no longer exists. However, doing that means that the
 675  * VFS layer can turn the dentry into a negative dentry.  We don't want
 676  * this, because the unlink is probably the result of an expire.
 677  * We simply d_drop it and add it to a expiring list in the super block,
 678  * which allows the dentry lookup to check for an incomplete expire.
 679  *
 680  * If a process is blocked on the dentry waiting for the expire to finish,
 681  * it will invalidate the dentry and try to mount with a new one.
 682  *
 683  * Also see autofs4_dir_rmdir()..
 684  */
 685 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
 686 {
 687         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 688         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 689         struct autofs_info *p_ino;
 690
 691         /* This allows root to remove symlinks */
 692         if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
 693                 return -EACCES;
 694
 695         if (atomic_dec_and_test(&ino->count)) {
 696                 p_ino = autofs4_dentry_ino(dentry->d_parent);
 697                 if (p_ino && dentry->d_parent != dentry)
 698                         atomic_dec(&p_ino->count);
 699         }
 700         dput(ino->dentry);
 701
 702         dentry->d_inode->i_size = 0;
 703         clear_nlink(dentry->d_inode);
 704
 705         dir->i_mtime = CURRENT_TIME;
 706
 707         spin_lock(&dcache_lock);
 708         spin_lock(&sbi->lookup_lock);
 709         if (list_empty(&ino->expiring))
 710                 list_add(&ino->expiring, &sbi->expiring_list);
 711         spin_unlock(&sbi->lookup_lock);
 712         spin_lock(&dentry->d_lock);
 713         __d_drop(dentry);
 714         spin_unlock(&dentry->d_lock);
 715         spin_unlock(&dcache_lock);
 716
 717         return 0;
 718 }
 719
 720 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
 721 {
 722         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 723         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 724         struct autofs_info *p_ino;
 725
 726         DPRINTK("dentry %p, removing %.*s",
 727                 dentry, dentry->d_name.len, dentry->d_name.name);
 728
 729         if (!autofs4_oz_mode(sbi))
 730                 return -EACCES;
 731
 732         spin_lock(&dcache_lock);
 733         if (!list_empty(&dentry->d_subdirs)) {
 734                 spin_unlock(&dcache_lock);
 735                 return -ENOTEMPTY;
 736         }
 737         spin_lock(&sbi->lookup_lock);
 738         if (list_empty(&ino->expiring))
 739                 list_add(&ino->expiring, &sbi->expiring_list);
 740         spin_unlock(&sbi->lookup_lock);
 741         spin_lock(&dentry->d_lock);
 742         __d_drop(dentry);
 743         spin_unlock(&dentry->d_lock);
 744         spin_unlock(&dcache_lock);
 745
 746         if (atomic_dec_and_test(&ino->count)) {
 747                 p_ino = autofs4_dentry_ino(dentry->d_parent);
 748                 if (p_ino && dentry->d_parent != dentry)
 749                         atomic_dec(&p_ino->count);
 750         }
 751         dput(ino->dentry);
 752         dentry->d_inode->i_size = 0;
 753         clear_nlink(dentry->d_inode);
 754
 755         if (dir->i_nlink)
 756                 drop_nlink(dir);
 757
 758         return 0;
 759 }
 760
 761 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 762 {
 763         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 764         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 765         struct autofs_info *p_ino;
 766         struct inode *inode;
 767
 768         if (!autofs4_oz_mode(sbi))
 769                 return -EACCES;
 770
 771         DPRINTK("dentry %p, creating %.*s",
 772                 dentry, dentry->d_name.len, dentry->d_name.name);
 773
 774         ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
 775         if (!ino)
 776                 return -ENOMEM;
 777
 778         spin_lock(&sbi->lookup_lock);
 779         if (!list_empty(&ino->active))
 780                 list_del_init(&ino->active);
 781         spin_unlock(&sbi->lookup_lock);
 782
 783         inode = autofs4_get_inode(dir->i_sb, ino);
 784         if (!inode) {
 785                 if (!dentry->d_fsdata)
 786                         kfree(ino);
 787                 return -ENOMEM;
 788         }
 789         d_add(dentry, inode);
 790
 791         if (dir == dir->i_sb->s_root->d_inode)
 792                 dentry->d_op = &autofs4_root_dentry_operations;
 793         else
 794                 dentry->d_op = &autofs4_dentry_operations;
 795
 796         dentry->d_fsdata = ino;
 797         ino->dentry = dget(dentry);
 798         atomic_inc(&ino->count);
 799         p_ino = autofs4_dentry_ino(dentry->d_parent);
 800         if (p_ino && dentry->d_parent != dentry)
 801                 atomic_inc(&p_ino->count);
 802         ino->inode = inode;
 803         inc_nlink(dir);
 804         dir->i_mtime = CURRENT_TIME;
 805
 806         return 0;
 807 }
 808
 809 /* Get/set timeout ioctl() operation */
 810 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
 811                                          unsigned long __user *p)
 812 {
 813         int rv;
 814         unsigned long ntimeout;
 815
 816         if ((rv = get_user(ntimeout, p)) ||
 817              (rv = put_user(sbi->exp_timeout/HZ, p)))
 818                 return rv;
 819
 820         if (ntimeout > ULONG_MAX/HZ)
 821                 sbi->exp_timeout = 0;
 822         else
 823                 sbi->exp_timeout = ntimeout * HZ;
 824
 825         return 0;
 826 }
 827
 828 /* Return protocol version */
 829 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
 830 {
 831         return put_user(sbi->version, p);
 832 }
 833
 834 /* Return protocol sub version */
 835 static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
 836 {
 837         return put_user(sbi->sub_version, p);
 838 }
 839
 840 /*
 841 * Tells the daemon whether it can umount the autofs mount.
 842 */
 843 static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
 844 {
 845         int status = 0;
 846
 847         if (may_umount(mnt))
 848                 status = 1;
 849
 850         DPRINTK("returning %d", status);
 851
 852         status = put_user(status, p);
 853
 854         return status;
 855 }
 856
 857 /* Identify autofs4_dentries - this is so we can tell if there's
 858    an extra dentry refcount or not.  We only hold a refcount on the
 859    dentry if its non-negative (ie, d_inode != NULL)
 860 */
 861 int is_autofs4_dentry(struct dentry *dentry)
 862 {
 863         return dentry && dentry->d_inode &&
 864                 (dentry->d_op == &autofs4_root_dentry_operations ||
 865                  dentry->d_op == &autofs4_dentry_operations) &&
 866                 dentry->d_fsdata != NULL;
 867 }
 868
 869 /*
 870  * ioctl()'s on the root directory is the chief method for the daemon to
 871  * generate kernel reactions
 872  */
 873 static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
 874                              unsigned int cmd, unsigned long arg)
 875 {
 876         struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
 877         void __user *p = (void __user *)arg;
 878
 879         DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
 880                 cmd,arg,sbi,task_pgrp_nr(current));
 881
 882         if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
 883              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
 884                 return -ENOTTY;
 885
 886         if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
 887                 return -EPERM;
 888
 889         switch(cmd) {
 890         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
 891                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
 892         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
 893                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
 894         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
 895                 autofs4_catatonic_mode(sbi);
 896                 return 0;
 897         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
 898                 return autofs4_get_protover(sbi, p);
 899         case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
 900                 return autofs4_get_protosubver(sbi, p);
 901         case AUTOFS_IOC_SETTIMEOUT:
 902                 return autofs4_get_set_timeout(sbi, p);
 903
 904         case AUTOFS_IOC_ASKUMOUNT:
 905                 return autofs4_ask_umount(filp->f_path.mnt, p);
 906
 907         /* return a single thing to expire */
 908         case AUTOFS_IOC_EXPIRE:
 909                 return autofs4_expire_run(inode->i_sb,filp->f_path.mnt,sbi, p);
 910         /* same as above, but can send multiple expires through pipe */
 911         case AUTOFS_IOC_EXPIRE_MULTI:
 912                 return autofs4_expire_multi(inode->i_sb,filp->f_path.mnt,sbi, p);
 913
 914         default:
 915                 return -ENOSYS;
 916         }
 917 }