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 const 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 const 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 const 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_path.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_path.dentry;
  99         struct vfsmount *mnt = file->f_path.mnt;
 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 <= 0) {
 141                         if (ret < 0)
 142                                 status = ret;
 143                         dcache_dir_close(inode, file);
 144                         goto out;
 145                 }
 146         }
 147
 148         if (d_mountpoint(dentry)) {
 149                 struct file *fp = NULL;
 150                 struct vfsmount *fp_mnt = mntget(mnt);
 151                 struct dentry *fp_dentry = dget(dentry);
 152
 153                 if (!autofs4_follow_mount(&fp_mnt, &fp_dentry)) {
 154                         dput(fp_dentry);
 155                         mntput(fp_mnt);
 156                         dcache_dir_close(inode, file);
 157                         goto out;
 158                 }
 159
 160                 fp = dentry_open(fp_dentry, fp_mnt, file->f_flags);
 161                 status = PTR_ERR(fp);
 162                 if (IS_ERR(fp)) {
 163                         dcache_dir_close(inode, file);
 164                         goto out;
 165                 }
 166                 cursor->d_fsdata = fp;
 167         }
 168         return 0;
 169 out:
 170         return status;
 171 }
 172
 173 static int autofs4_dir_close(struct inode *inode, struct file *file)
 174 {
 175         struct dentry *dentry = file->f_path.dentry;
 176         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 177         struct dentry *cursor = file->private_data;
 178         int status = 0;
 179
 180         DPRINTK("file=%p dentry=%p %.*s",
 181                 file, dentry, dentry->d_name.len, dentry->d_name.name);
 182
 183         if (autofs4_oz_mode(sbi))
 184                 goto out;
 185
 186         if (autofs4_ispending(dentry)) {
 187                 DPRINTK("dentry busy");
 188                 status = -EBUSY;
 189                 goto out;
 190         }
 191
 192         if (d_mountpoint(dentry)) {
 193                 struct file *fp = cursor->d_fsdata;
 194                 if (!fp) {
 195                         status = -ENOENT;
 196                         goto out;
 197                 }
 198                 filp_close(fp, current->files);
 199         }
 200 out:
 201         dcache_dir_close(inode, file);
 202         return status;
 203 }
 204
 205 static int autofs4_dir_readdir(struct file *file, void *dirent, filldir_t filldir)
 206 {
 207         struct dentry *dentry = file->f_path.dentry;
 208         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 209         struct dentry *cursor = file->private_data;
 210         int status;
 211
 212         DPRINTK("file=%p dentry=%p %.*s",
 213                 file, dentry, dentry->d_name.len, dentry->d_name.name);
 214
 215         if (autofs4_oz_mode(sbi))
 216                 goto out;
 217
 218         if (autofs4_ispending(dentry)) {
 219                 DPRINTK("dentry busy");
 220                 return -EBUSY;
 221         }
 222
 223         if (d_mountpoint(dentry)) {
 224                 struct file *fp = cursor->d_fsdata;
 225
 226                 if (!fp)
 227                         return -ENOENT;
 228
 229                 if (!fp->f_op || !fp->f_op->readdir)
 230                         goto out;
 231
 232                 status = vfs_readdir(fp, filldir, dirent);
 233                 file->f_pos = fp->f_pos;
 234                 if (status)
 235                         autofs4_copy_atime(file, fp);
 236                 return status;
 237         }
 238 out:
 239         return dcache_readdir(file, dirent, filldir);
 240 }
 241
 242 static int try_to_fill_dentry(struct dentry *dentry, int flags)
 243 {
 244         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 245         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 246         int status = 0;
 247
 248         /* Block on any pending expiry here; invalidate the dentry
 249            when expiration is done to trigger mount request with a new
 250            dentry */
 251         if (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
 252                 DPRINTK("waiting for expire %p name=%.*s",
 253                          dentry, dentry->d_name.len, dentry->d_name.name);
 254
 255                 status = autofs4_wait(sbi, dentry, NFY_NONE);
 256
 257                 DPRINTK("expire done status=%d", status);
 258
 259                 /*
 260                  * If the directory still exists the mount request must
 261                  * continue otherwise it can't be followed at the right
 262                  * time during the walk.
 263                  */
 264                 status = d_invalidate(dentry);
 265                 if (status != -EBUSY)
 266                         return -EAGAIN;
 267         }
 268
 269         DPRINTK("dentry=%p %.*s ino=%p",
 270                  dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode);
 271
 272         /*
 273          * Wait for a pending mount, triggering one if there
 274          * isn't one already
 275          */
 276         if (dentry->d_inode == NULL) {
 277                 DPRINTK("waiting for mount name=%.*s",
 278                          dentry->d_name.len, dentry->d_name.name);
 279
 280                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 281
 282                 DPRINTK("mount done status=%d", status);
 283
 284                 /* Turn this into a real negative dentry? */
 285                 if (status == -ENOENT) {
 286                         spin_lock(&dentry->d_lock);
 287                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 288                         spin_unlock(&dentry->d_lock);
 289                         return status;
 290                 } else if (status) {
 291                         /* Return a negative dentry, but leave it "pending" */
 292                         return status;
 293                 }
 294         /* Trigger mount for path component or follow link */
 295         } else if (flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY) ||
 296                         current->link_count) {
 297                 DPRINTK("waiting for mount name=%.*s",
 298                         dentry->d_name.len, dentry->d_name.name);
 299
 300                 spin_lock(&dentry->d_lock);
 301                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 302                 spin_unlock(&dentry->d_lock);
 303                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 304
 305                 DPRINTK("mount done status=%d", status);
 306
 307                 if (status) {
 308                         spin_lock(&dentry->d_lock);
 309                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 310                         spin_unlock(&dentry->d_lock);
 311                         return status;
 312                 }
 313         }
 314
 315         /* Initialize expiry counter after successful mount */
 316         if (ino)
 317                 ino->last_used = jiffies;
 318
 319         spin_lock(&dentry->d_lock);
 320         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 321         spin_unlock(&dentry->d_lock);
 322         return status;
 323 }
 324
 325 /* For autofs direct mounts the follow link triggers the mount */
 326 static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
 327 {
 328         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 329         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 330         int oz_mode = autofs4_oz_mode(sbi);
 331         unsigned int lookup_type;
 332         int status;
 333
 334         DPRINTK("dentry=%p %.*s oz_mode=%d nd->flags=%d",
 335                 dentry, dentry->d_name.len, dentry->d_name.name, oz_mode,
 336                 nd->flags);
 337
 338         /* If it's our master or we shouldn't trigger a mount we're done */
 339         lookup_type = nd->flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY);
 340         if (oz_mode || !lookup_type)
 341                 goto done;
 342
 343         /* If an expire request is pending wait for it. */
 344         if (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
 345                 DPRINTK("waiting for active request %p name=%.*s",
 346                         dentry, dentry->d_name.len, dentry->d_name.name);
 347
 348                 status = autofs4_wait(sbi, dentry, NFY_NONE);
 349
 350                 DPRINTK("request done status=%d", status);
 351         }
 352
 353         /*
 354          * If the dentry contains directories then it is an
 355          * autofs multi-mount with no root mount offset. So
 356          * don't try to mount it again.
 357          */
 358         spin_lock(&dcache_lock);
 359         if (!d_mountpoint(dentry) && __simple_empty(dentry)) {
 360                 spin_unlock(&dcache_lock);
 361
 362                 status = try_to_fill_dentry(dentry, 0);
 363                 if (status)
 364                         goto out_error;
 365
 366                 /*
 367                  * The mount succeeded but if there is no root mount
 368                  * it must be an autofs multi-mount with no root offset
 369                  * so we don't need to follow the mount.
 370                  */
 371                 if (d_mountpoint(dentry)) {
 372                         if (!autofs4_follow_mount(&nd->mnt, &nd->dentry)) {
 373                                 status = -ENOENT;
 374                                 goto out_error;
 375                         }
 376                 }
 377
 378                 goto done;
 379         }
 380         spin_unlock(&dcache_lock);
 381
 382 done:
 383         return NULL;
 384
 385 out_error:
 386         path_release(nd);
 387         return ERR_PTR(status);
 388 }
 389
 390 /*
 391  * Revalidate is called on every cache lookup.  Some of those
 392  * cache lookups may actually happen while the dentry is not
 393  * yet completely filled in, and revalidate has to delay such
 394  * lookups..
 395  */
 396 static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
 397 {
 398         struct inode *dir = dentry->d_parent->d_inode;
 399         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 400         int oz_mode = autofs4_oz_mode(sbi);
 401         int flags = nd ? nd->flags : 0;
 402         int status = 1;
 403
 404         /* Pending dentry */
 405         if (autofs4_ispending(dentry)) {
 406                 /* The daemon never causes a mount to trigger */
 407                 if (oz_mode)
 408                         return 1;
 409
 410                 /*
 411                  * A zero status is success otherwise we have a
 412                  * negative error code.
 413                  */
 414                 status = try_to_fill_dentry(dentry, flags);
 415                 if (status == 0)
 416                         return 1;
 417
 418                 /*
 419                  * A status of EAGAIN here means that the dentry has gone
 420                  * away while waiting for an expire to complete. If we are
 421                  * racing with expire lookup will wait for it so this must
 422                  * be a revalidate and we need to send it to lookup.
 423                  */
 424                 if (status == -EAGAIN)
 425                         return 0;
 426
 427                 return status;
 428         }
 429
 430         /* Negative dentry.. invalidate if "old" */
 431         if (dentry->d_inode == NULL)
 432                 return 0;
 433
 434         /* Check for a non-mountpoint directory with no contents */
 435         spin_lock(&dcache_lock);
 436         if (S_ISDIR(dentry->d_inode->i_mode) &&
 437             !d_mountpoint(dentry) &&
 438             __simple_empty(dentry)) {
 439                 DPRINTK("dentry=%p %.*s, emptydir",
 440                          dentry, dentry->d_name.len, dentry->d_name.name);
 441                 spin_unlock(&dcache_lock);
 442                 /* The daemon never causes a mount to trigger */
 443                 if (oz_mode)
 444                         return 1;
 445
 446                 /*
 447                  * A zero status is success otherwise we have a
 448                  * negative error code.
 449                  */
 450                 status = try_to_fill_dentry(dentry, flags);
 451                 if (status == 0)
 452                         return 1;
 453
 454                 return status;
 455         }
 456         spin_unlock(&dcache_lock);
 457
 458         return 1;
 459 }
 460
 461 void autofs4_dentry_release(struct dentry *de)
 462 {
 463         struct autofs_info *inf;
 464
 465         DPRINTK("releasing %p", de);
 466
 467         inf = autofs4_dentry_ino(de);
 468         de->d_fsdata = NULL;
 469
 470         if (inf) {
 471                 struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb);
 472
 473                 if (sbi) {
 474                         spin_lock(&sbi->rehash_lock);
 475                         if (!list_empty(&inf->rehash))
 476                                 list_del(&inf->rehash);
 477                         spin_unlock(&sbi->rehash_lock);
 478                 }
 479
 480                 inf->dentry = NULL;
 481                 inf->inode = NULL;
 482
 483                 autofs4_free_ino(inf);
 484         }
 485 }
 486
 487 /* For dentries of directories in the root dir */
 488 static struct dentry_operations autofs4_root_dentry_operations = {
 489         .d_revalidate   = autofs4_revalidate,
 490         .d_release      = autofs4_dentry_release,
 491 };
 492
 493 /* For other dentries */
 494 static struct dentry_operations autofs4_dentry_operations = {
 495         .d_revalidate   = autofs4_revalidate,
 496         .d_release      = autofs4_dentry_release,
 497 };
 498
 499 static struct dentry *autofs4_lookup_unhashed(struct autofs_sb_info *sbi, struct dentry *parent, struct qstr *name)
 500 {
 501         unsigned int len = name->len;
 502         unsigned int hash = name->hash;
 503         const unsigned char *str = name->name;
 504         struct list_head *p, *head;
 505
 506         spin_lock(&dcache_lock);
 507         spin_lock(&sbi->rehash_lock);
 508         head = &sbi->rehash_list;
 509         list_for_each(p, head) {
 510                 struct autofs_info *ino;
 511                 struct dentry *dentry;
 512                 struct qstr *qstr;
 513
 514                 ino = list_entry(p, struct autofs_info, rehash);
 515                 dentry = ino->dentry;
 516
 517                 spin_lock(&dentry->d_lock);
 518
 519                 /* Bad luck, we've already been dentry_iput */
 520                 if (!dentry->d_inode)
 521                         goto next;
 522
 523                 qstr = &dentry->d_name;
 524
 525                 if (dentry->d_name.hash != hash)
 526                         goto next;
 527                 if (dentry->d_parent != parent)
 528                         goto next;
 529
 530                 if (qstr->len != len)
 531                         goto next;
 532                 if (memcmp(qstr->name, str, len))
 533                         goto next;
 534
 535                 if (d_unhashed(dentry)) {
 536                         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 537                         struct inode *inode = dentry->d_inode;
 538
 539                         list_del_init(&ino->rehash);
 540                         dget(dentry);
 541                         /*
 542                          * Make the rehashed dentry negative so the VFS
 543                          * behaves as it should.
 544                          */
 545                         if (inode) {
 546                                 dentry->d_inode = NULL;
 547                                 list_del_init(&dentry->d_alias);
 548                                 spin_unlock(&dentry->d_lock);
 549                                 spin_unlock(&sbi->rehash_lock);
 550                                 spin_unlock(&dcache_lock);
 551                                 iput(inode);
 552                                 return dentry;
 553                         }
 554                         spin_unlock(&dentry->d_lock);
 555                         spin_unlock(&sbi->rehash_lock);
 556                         spin_unlock(&dcache_lock);
 557                         return dentry;
 558                 }
 559 next:
 560                 spin_unlock(&dentry->d_lock);
 561         }
 562         spin_unlock(&sbi->rehash_lock);
 563         spin_unlock(&dcache_lock);
 564
 565         return NULL;
 566 }
 567
 568 /* Lookups in the root directory */
 569 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 570 {
 571         struct autofs_sb_info *sbi;
 572         struct dentry *unhashed;
 573         int oz_mode;
 574
 575         DPRINTK("name = %.*s",
 576                 dentry->d_name.len, dentry->d_name.name);
 577
 578         /* File name too long to exist */
 579         if (dentry->d_name.len > NAME_MAX)
 580                 return ERR_PTR(-ENAMETOOLONG);
 581
 582         sbi = autofs4_sbi(dir->i_sb);
 583         oz_mode = autofs4_oz_mode(sbi);
 584
 585         DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
 586                  current->pid, process_group(current), sbi->catatonic, oz_mode);
 587
 588         unhashed = autofs4_lookup_unhashed(sbi, dentry->d_parent, &dentry->d_name);
 589         if (!unhashed) {
 590                 /*
 591                  * Mark the dentry incomplete, but add it. This is needed so
 592                  * that the VFS layer knows about the dentry, and we can count
 593                  * on catching any lookups through the revalidate.
 594                  *
 595                  * Let all the hard work be done by the revalidate function that
 596                  * needs to be able to do this anyway..
 597                  *
 598                  * We need to do this before we release the directory semaphore.
 599                  */
 600                 dentry->d_op = &autofs4_root_dentry_operations;
 601
 602                 dentry->d_fsdata = NULL;
 603                 d_add(dentry, NULL);
 604         } else {
 605                 struct autofs_info *ino = autofs4_dentry_ino(unhashed);
 606                 DPRINTK("rehash %p with %p", dentry, unhashed);
 607                 /*
 608                  * If we are racing with expire the request might not
 609                  * be quite complete but the directory has been removed
 610                  * so it must have been successful, so just wait for it.
 611                  */
 612                 if (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
 613                         DPRINTK("wait for incomplete expire %p name=%.*s",
 614                                 unhashed, unhashed->d_name.len,
 615                                 unhashed->d_name.name);
 616                         autofs4_wait(sbi, unhashed, NFY_NONE);
 617                         DPRINTK("request completed");
 618                 }
 619                 d_rehash(unhashed);
 620                 dentry = unhashed;
 621         }
 622
 623         if (!oz_mode) {
 624                 spin_lock(&dentry->d_lock);
 625                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 626                 spin_unlock(&dentry->d_lock);
 627         }
 628
 629         if (dentry->d_op && dentry->d_op->d_revalidate) {
 630                 mutex_unlock(&dir->i_mutex);
 631                 (dentry->d_op->d_revalidate)(dentry, nd);
 632                 mutex_lock(&dir->i_mutex);
 633         }
 634
 635         /*
 636          * If we are still pending, check if we had to handle
 637          * a signal. If so we can force a restart..
 638          */
 639         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 640                 /* See if we were interrupted */
 641                 if (signal_pending(current)) {
 642                         sigset_t *sigset = &current->pending.signal;
 643                         if (sigismember (sigset, SIGKILL) ||
 644                             sigismember (sigset, SIGQUIT) ||
 645                             sigismember (sigset, SIGINT)) {
 646                             if (unhashed)
 647                                 dput(unhashed);
 648                             return ERR_PTR(-ERESTARTNOINTR);
 649                         }
 650                 }
 651                 spin_lock(&dentry->d_lock);
 652                 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 653                 spin_unlock(&dentry->d_lock);
 654         }
 655
 656         /*
 657          * If this dentry is unhashed, then we shouldn't honour this
 658          * lookup.  Returning ENOENT here doesn't do the right thing
 659          * for all system calls, but it should be OK for the operations
 660          * we permit from an autofs.
 661          */
 662         if (dentry->d_inode && d_unhashed(dentry)) {
 663                 /*
 664                  * A user space application can (and has done in the past)
 665                  * remove and re-create this directory during the callback.
 666                  * This can leave us with an unhashed dentry, but a
 667                  * successful mount!  So we need to perform another
 668                  * cached lookup in case the dentry now exists.
 669                  */
 670                 struct dentry *parent = dentry->d_parent;
 671                 struct dentry *new = d_lookup(parent, &dentry->d_name);
 672                 if (new != NULL)
 673                         dentry = new;
 674                 else
 675                         dentry = ERR_PTR(-ENOENT);
 676
 677                 if (unhashed)
 678                         dput(unhashed);
 679
 680                 return dentry;
 681         }
 682
 683         if (unhashed)
 684                 return dentry;
 685
 686         return NULL;
 687 }
 688
 689 static int autofs4_dir_symlink(struct inode *dir,
 690                                struct dentry *dentry,
 691                                const char *symname)
 692 {
 693         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 694         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 695         struct autofs_info *p_ino;
 696         struct inode *inode;
 697         char *cp;
 698
 699         DPRINTK("%s <- %.*s", symname,
 700                 dentry->d_name.len, dentry->d_name.name);
 701
 702         if (!autofs4_oz_mode(sbi))
 703                 return -EACCES;
 704
 705         ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
 706         if (ino == NULL)
 707                 return -ENOSPC;
 708
 709         ino->size = strlen(symname);
 710         ino->u.symlink = cp = kmalloc(ino->size + 1, GFP_KERNEL);
 711
 712         if (cp == NULL) {
 713                 kfree(ino);
 714                 return -ENOSPC;
 715         }
 716
 717         strcpy(cp, symname);
 718
 719         inode = autofs4_get_inode(dir->i_sb, ino);
 720         d_instantiate(dentry, inode);
 721
 722         if (dir == dir->i_sb->s_root->d_inode)
 723                 dentry->d_op = &autofs4_root_dentry_operations;
 724         else
 725                 dentry->d_op = &autofs4_dentry_operations;
 726
 727         dentry->d_fsdata = ino;
 728         ino->dentry = dget(dentry);
 729         atomic_inc(&ino->count);
 730         p_ino = autofs4_dentry_ino(dentry->d_parent);
 731         if (p_ino && dentry->d_parent != dentry)
 732                 atomic_inc(&p_ino->count);
 733         ino->inode = inode;
 734
 735         dir->i_mtime = CURRENT_TIME;
 736
 737         return 0;
 738 }
 739
 740 /*
 741  * NOTE!
 742  *
 743  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 744  * that the file no longer exists. However, doing that means that the
 745  * VFS layer can turn the dentry into a negative dentry.  We don't want
 746  * this, because the unlink is probably the result of an expire.
 747  * We simply d_drop it and add it to a rehash candidates list in the
 748  * super block, which allows the dentry lookup to reuse it retaining
 749  * the flags, such as expire in progress, in case we're racing with expire.
 750  *
 751  * If a process is blocked on the dentry waiting for the expire to finish,
 752  * it will invalidate the dentry and try to mount with a new one.
 753  *
 754  * Also see autofs4_dir_rmdir()..
 755  */
 756 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
 757 {
 758         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 759         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 760         struct autofs_info *p_ino;
 761
 762         /* This allows root to remove symlinks */
 763         if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
 764                 return -EACCES;
 765
 766         if (atomic_dec_and_test(&ino->count)) {
 767                 p_ino = autofs4_dentry_ino(dentry->d_parent);
 768                 if (p_ino && dentry->d_parent != dentry)
 769                         atomic_dec(&p_ino->count);
 770         }
 771         dput(ino->dentry);
 772
 773         dentry->d_inode->i_size = 0;
 774         clear_nlink(dentry->d_inode);
 775
 776         dir->i_mtime = CURRENT_TIME;
 777
 778         spin_lock(&dcache_lock);
 779         spin_lock(&sbi->rehash_lock);
 780         list_add(&ino->rehash, &sbi->rehash_list);
 781         spin_unlock(&sbi->rehash_lock);
 782         spin_lock(&dentry->d_lock);
 783         __d_drop(dentry);
 784         spin_unlock(&dentry->d_lock);
 785         spin_unlock(&dcache_lock);
 786
 787         return 0;
 788 }
 789
 790 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
 791 {
 792         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 793         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 794         struct autofs_info *p_ino;
 795
 796         DPRINTK("dentry %p, removing %.*s",
 797                 dentry, dentry->d_name.len, dentry->d_name.name);
 798
 799         if (!autofs4_oz_mode(sbi))
 800                 return -EACCES;
 801
 802         spin_lock(&dcache_lock);
 803         if (!list_empty(&dentry->d_subdirs)) {
 804                 spin_unlock(&dcache_lock);
 805                 return -ENOTEMPTY;
 806         }
 807         spin_lock(&sbi->rehash_lock);
 808         list_add(&ino->rehash, &sbi->rehash_list);
 809         spin_unlock(&sbi->rehash_lock);
 810         spin_lock(&dentry->d_lock);
 811         __d_drop(dentry);
 812         spin_unlock(&dentry->d_lock);
 813         spin_unlock(&dcache_lock);
 814
 815         if (atomic_dec_and_test(&ino->count)) {
 816                 p_ino = autofs4_dentry_ino(dentry->d_parent);
 817                 if (p_ino && dentry->d_parent != dentry)
 818                         atomic_dec(&p_ino->count);
 819         }
 820         dput(ino->dentry);
 821         dentry->d_inode->i_size = 0;
 822         clear_nlink(dentry->d_inode);
 823
 824         if (dir->i_nlink)
 825                 drop_nlink(dir);
 826
 827         return 0;
 828 }
 829
 830 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 831 {
 832         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 833         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 834         struct autofs_info *p_ino;
 835         struct inode *inode;
 836
 837         if ( !autofs4_oz_mode(sbi) )
 838                 return -EACCES;
 839
 840         DPRINTK("dentry %p, creating %.*s",
 841                 dentry, dentry->d_name.len, dentry->d_name.name);
 842
 843         ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
 844         if (ino == NULL)
 845                 return -ENOSPC;
 846
 847         inode = autofs4_get_inode(dir->i_sb, ino);
 848         d_instantiate(dentry, inode);
 849
 850         if (dir == dir->i_sb->s_root->d_inode)
 851                 dentry->d_op = &autofs4_root_dentry_operations;
 852         else
 853                 dentry->d_op = &autofs4_dentry_operations;
 854
 855         dentry->d_fsdata = ino;
 856         ino->dentry = dget(dentry);
 857         atomic_inc(&ino->count);
 858         p_ino = autofs4_dentry_ino(dentry->d_parent);
 859         if (p_ino && dentry->d_parent != dentry)
 860                 atomic_inc(&p_ino->count);
 861         ino->inode = inode;
 862         inc_nlink(dir);
 863         dir->i_mtime = CURRENT_TIME;
 864
 865         return 0;
 866 }
 867
 868 /* Get/set timeout ioctl() operation */
 869 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
 870                                          unsigned long __user *p)
 871 {
 872         int rv;
 873         unsigned long ntimeout;
 874
 875         if ( (rv = get_user(ntimeout, p)) ||
 876              (rv = put_user(sbi->exp_timeout/HZ, p)) )
 877                 return rv;
 878
 879         if ( ntimeout > ULONG_MAX/HZ )
 880                 sbi->exp_timeout = 0;
 881         else
 882                 sbi->exp_timeout = ntimeout * HZ;
 883
 884         return 0;
 885 }
 886
 887 /* Return protocol version */
 888 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
 889 {
 890         return put_user(sbi->version, p);
 891 }
 892
 893 /* Return protocol sub version */
 894 static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
 895 {
 896         return put_user(sbi->sub_version, p);
 897 }
 898
 899 /*
 900  * Tells the daemon whether we need to reghost or not. Also, clears
 901  * the reghost_needed flag.
 902  */
 903 static inline int autofs4_ask_reghost(struct autofs_sb_info *sbi, int __user *p)
 904 {
 905         int status;
 906
 907         DPRINTK("returning %d", sbi->needs_reghost);
 908
 909         status = put_user(sbi->needs_reghost, p);
 910         if ( status )
 911                 return status;
 912
 913         sbi->needs_reghost = 0;
 914         return 0;
 915 }
 916
 917 /*
 918  * Enable / Disable reghosting ioctl() operation
 919  */
 920 static inline int autofs4_toggle_reghost(struct autofs_sb_info *sbi, int __user *p)
 921 {
 922         int status;
 923         int val;
 924
 925         status = get_user(val, p);
 926
 927         DPRINTK("reghost = %d", val);
 928
 929         if (status)
 930                 return status;
 931
 932         /* turn on/off reghosting, with the val */
 933         sbi->reghost_enabled = val;
 934         return 0;
 935 }
 936
 937 /*
 938 * Tells the daemon whether it can umount the autofs mount.
 939 */
 940 static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
 941 {
 942         int status = 0;
 943
 944         if (may_umount(mnt))
 945                 status = 1;
 946
 947         DPRINTK("returning %d", status);
 948
 949         status = put_user(status, p);
 950
 951         return status;
 952 }
 953
 954 /* Identify autofs4_dentries - this is so we can tell if there's
 955    an extra dentry refcount or not.  We only hold a refcount on the
 956    dentry if its non-negative (ie, d_inode != NULL)
 957 */
 958 int is_autofs4_dentry(struct dentry *dentry)
 959 {
 960         return dentry && dentry->d_inode &&
 961                 (dentry->d_op == &autofs4_root_dentry_operations ||
 962                  dentry->d_op == &autofs4_dentry_operations) &&
 963                 dentry->d_fsdata != NULL;
 964 }
 965
 966 /*
 967  * ioctl()'s on the root directory is the chief method for the daemon to
 968  * generate kernel reactions
 969  */
 970 static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
 971                              unsigned int cmd, unsigned long arg)
 972 {
 973         struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
 974         void __user *p = (void __user *)arg;
 975
 976         DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
 977                 cmd,arg,sbi,process_group(current));
 978
 979         if ( _IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
 980              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT )
 981                 return -ENOTTY;
 982
 983         if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
 984                 return -EPERM;
 985
 986         switch(cmd) {
 987         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
 988                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
 989         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
 990                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
 991         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
 992                 autofs4_catatonic_mode(sbi);
 993                 return 0;
 994         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
 995                 return autofs4_get_protover(sbi, p);
 996         case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
 997                 return autofs4_get_protosubver(sbi, p);
 998         case AUTOFS_IOC_SETTIMEOUT:
 999                 return autofs4_get_set_timeout(sbi, p);
1000
1001         case AUTOFS_IOC_TOGGLEREGHOST:
1002                 return autofs4_toggle_reghost(sbi, p);
1003         case AUTOFS_IOC_ASKREGHOST:
1004                 return autofs4_ask_reghost(sbi, p);
1005
1006         case AUTOFS_IOC_ASKUMOUNT:
1007                 return autofs4_ask_umount(filp->f_path.mnt, p);
1008
1009         /* return a single thing to expire */
1010         case AUTOFS_IOC_EXPIRE:
1011                 return autofs4_expire_run(inode->i_sb,filp->f_path.mnt,sbi, p);
1012         /* same as above, but can send multiple expires through pipe */
1013         case AUTOFS_IOC_EXPIRE_MULTI:
1014                 return autofs4_expire_multi(inode->i_sb,filp->f_path.mnt,sbi, p);
1015
1016         default:
1017                 return -ENOSYS;
1018         }
1019 }