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 int autofs4_dir_close(struct inode *inode, struct file *file);
  29 static int autofs4_dir_readdir(struct file * filp, void * dirent, filldir_t filldir);
  30 static int autofs4_root_readdir(struct file * filp, void * dirent, filldir_t filldir);
  31 static struct dentry *autofs4_lookup(struct inode *,struct dentry *, struct nameidata *);
  32 static void *autofs4_follow_link(struct dentry *, struct nameidata *);
  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        = autofs4_root_readdir,
  39         .ioctl          = autofs4_root_ioctl,
  40 };
  41
  42 const struct file_operations autofs4_dir_operations = {
  43         .open           = autofs4_dir_open,
  44         .release        = autofs4_dir_close,
  45         .read           = generic_read_dir,
  46         .readdir        = autofs4_dir_readdir,
  47 };
  48
  49 const struct inode_operations autofs4_indirect_root_inode_operations = {
  50         .lookup         = autofs4_lookup,
  51         .unlink         = autofs4_dir_unlink,
  52         .symlink        = autofs4_dir_symlink,
  53         .mkdir          = autofs4_dir_mkdir,
  54         .rmdir          = autofs4_dir_rmdir,
  55 };
  56
  57 const struct inode_operations autofs4_direct_root_inode_operations = {
  58         .lookup         = autofs4_lookup,
  59         .unlink         = autofs4_dir_unlink,
  60         .mkdir          = autofs4_dir_mkdir,
  61         .rmdir          = autofs4_dir_rmdir,
  62         .follow_link    = autofs4_follow_link,
  63 };
  64
  65 const struct inode_operations autofs4_dir_inode_operations = {
  66         .lookup         = autofs4_lookup,
  67         .unlink         = autofs4_dir_unlink,
  68         .symlink        = autofs4_dir_symlink,
  69         .mkdir          = autofs4_dir_mkdir,
  70         .rmdir          = autofs4_dir_rmdir,
  71 };
  72
  73 static int autofs4_root_readdir(struct file *file, void *dirent,
  74                                 filldir_t filldir)
  75 {
  76         struct autofs_sb_info *sbi = autofs4_sbi(file->f_path.dentry->d_sb);
  77         int oz_mode = autofs4_oz_mode(sbi);
  78
  79         DPRINTK("called, filp->f_pos = %lld", file->f_pos);
  80
  81         /*
  82          * Don't set reghost flag if:
  83          * 1) f_pos is larger than zero -- we've already been here.
  84          * 2) we haven't even enabled reghosting in the 1st place.
  85          * 3) this is the daemon doing a readdir
  86          */
  87         if (oz_mode && file->f_pos == 0 && sbi->reghost_enabled)
  88                 sbi->needs_reghost = 1;
  89
  90         DPRINTK("needs_reghost = %d", sbi->needs_reghost);
  91
  92         return dcache_readdir(file, dirent, filldir);
  93 }
  94
  95 static int autofs4_dir_open(struct inode *inode, struct file *file)
  96 {
  97         struct dentry *dentry = file->f_path.dentry;
  98         struct vfsmount *mnt = file->f_path.mnt;
  99         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 100         struct dentry *cursor;
 101         int status;
 102
 103         status = dcache_dir_open(inode, file);
 104         if (status)
 105                 goto out;
 106
 107         cursor = file->private_data;
 108         cursor->d_fsdata = NULL;
 109
 110         DPRINTK("file=%p dentry=%p %.*s",
 111                 file, dentry, dentry->d_name.len, dentry->d_name.name);
 112
 113         if (autofs4_oz_mode(sbi))
 114                 goto out;
 115
 116         if (autofs4_ispending(dentry)) {
 117                 DPRINTK("dentry busy");
 118                 dcache_dir_close(inode, file);
 119                 status = -EBUSY;
 120                 goto out;
 121         }
 122
 123         status = -ENOENT;
 124         if (!d_mountpoint(dentry) && dentry->d_op && dentry->d_op->d_revalidate) {
 125                 struct nameidata nd;
 126                 int empty, ret;
 127
 128                 /* In case there are stale directory dentrys from a failed mount */
 129                 spin_lock(&dcache_lock);
 130                 empty = list_empty(&dentry->d_subdirs);
 131                 spin_unlock(&dcache_lock);
 132
 133                 if (!empty)
 134                         d_invalidate(dentry);
 135
 136                 nd.flags = LOOKUP_DIRECTORY;
 137                 ret = (dentry->d_op->d_revalidate)(dentry, &nd);
 138
 139                 if (ret <= 0) {
 140                         if (ret < 0)
 141                                 status = ret;
 142                         dcache_dir_close(inode, file);
 143                         goto out;
 144                 }
 145         }
 146
 147         if (d_mountpoint(dentry)) {
 148                 struct file *fp = NULL;
 149                 struct vfsmount *fp_mnt = mntget(mnt);
 150                 struct dentry *fp_dentry = dget(dentry);
 151
 152                 if (!autofs4_follow_mount(&fp_mnt, &fp_dentry)) {
 153                         dput(fp_dentry);
 154                         mntput(fp_mnt);
 155                         dcache_dir_close(inode, file);
 156                         goto out;
 157                 }
 158
 159                 fp = dentry_open(fp_dentry, fp_mnt, file->f_flags);
 160                 status = PTR_ERR(fp);
 161                 if (IS_ERR(fp)) {
 162                         dcache_dir_close(inode, file);
 163                         goto out;
 164                 }
 165                 cursor->d_fsdata = fp;
 166         }
 167         return 0;
 168 out:
 169         return status;
 170 }
 171
 172 static int autofs4_dir_close(struct inode *inode, struct file *file)
 173 {
 174         struct dentry *dentry = file->f_path.dentry;
 175         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 176         struct dentry *cursor = file->private_data;
 177         int status = 0;
 178
 179         DPRINTK("file=%p dentry=%p %.*s",
 180                 file, dentry, dentry->d_name.len, dentry->d_name.name);
 181
 182         if (autofs4_oz_mode(sbi))
 183                 goto out;
 184
 185         if (autofs4_ispending(dentry)) {
 186                 DPRINTK("dentry busy");
 187                 status = -EBUSY;
 188                 goto out;
 189         }
 190
 191         if (d_mountpoint(dentry)) {
 192                 struct file *fp = cursor->d_fsdata;
 193                 if (!fp) {
 194                         status = -ENOENT;
 195                         goto out;
 196                 }
 197                 filp_close(fp, current->files);
 198         }
 199 out:
 200         dcache_dir_close(inode, file);
 201         return status;
 202 }
 203
 204 static int autofs4_dir_readdir(struct file *file, void *dirent, filldir_t filldir)
 205 {
 206         struct dentry *dentry = file->f_path.dentry;
 207         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 208         struct dentry *cursor = file->private_data;
 209         int status;
 210
 211         DPRINTK("file=%p dentry=%p %.*s",
 212                 file, dentry, dentry->d_name.len, dentry->d_name.name);
 213
 214         if (autofs4_oz_mode(sbi))
 215                 goto out;
 216
 217         if (autofs4_ispending(dentry)) {
 218                 DPRINTK("dentry busy");
 219                 return -EBUSY;
 220         }
 221
 222         if (d_mountpoint(dentry)) {
 223                 struct file *fp = cursor->d_fsdata;
 224
 225                 if (!fp)
 226                         return -ENOENT;
 227
 228                 if (!fp->f_op || !fp->f_op->readdir)
 229                         goto out;
 230
 231                 status = vfs_readdir(fp, filldir, dirent);
 232                 file->f_pos = fp->f_pos;
 233                 if (status)
 234                         autofs4_copy_atime(file, fp);
 235                 return status;
 236         }
 237 out:
 238         return dcache_readdir(file, dirent, filldir);
 239 }
 240
 241 static int try_to_fill_dentry(struct dentry *dentry, int flags)
 242 {
 243         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 244         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 245         int status = 0;
 246
 247         /* Block on any pending expiry here; invalidate the dentry
 248            when expiration is done to trigger mount request with a new
 249            dentry */
 250         if (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
 251                 DPRINTK("waiting for expire %p name=%.*s",
 252                          dentry, dentry->d_name.len, dentry->d_name.name);
 253
 254                 status = autofs4_wait(sbi, dentry, NFY_NONE);
 255
 256                 DPRINTK("expire done status=%d", status);
 257
 258                 /*
 259                  * If the directory still exists the mount request must
 260                  * continue otherwise it can't be followed at the right
 261                  * time during the walk.
 262                  */
 263                 status = d_invalidate(dentry);
 264                 if (status != -EBUSY)
 265                         return -EAGAIN;
 266         }
 267
 268         DPRINTK("dentry=%p %.*s ino=%p",
 269                  dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode);
 270
 271         /*
 272          * Wait for a pending mount, triggering one if there
 273          * isn't one already
 274          */
 275         if (dentry->d_inode == NULL) {
 276                 DPRINTK("waiting for mount name=%.*s",
 277                          dentry->d_name.len, dentry->d_name.name);
 278
 279                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 280
 281                 DPRINTK("mount done status=%d", status);
 282
 283                 /* Turn this into a real negative dentry? */
 284                 if (status == -ENOENT) {
 285                         spin_lock(&dentry->d_lock);
 286                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 287                         spin_unlock(&dentry->d_lock);
 288                         return status;
 289                 } else if (status) {
 290                         /* Return a negative dentry, but leave it "pending" */
 291                         return status;
 292                 }
 293         /* Trigger mount for path component or follow link */
 294         } else if (flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY) ||
 295                         current->link_count) {
 296                 DPRINTK("waiting for mount name=%.*s",
 297                         dentry->d_name.len, dentry->d_name.name);
 298
 299                 spin_lock(&dentry->d_lock);
 300                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 301                 spin_unlock(&dentry->d_lock);
 302                 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 303
 304                 DPRINTK("mount done status=%d", status);
 305
 306                 if (status) {
 307                         spin_lock(&dentry->d_lock);
 308                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 309                         spin_unlock(&dentry->d_lock);
 310                         return status;
 311                 }
 312         }
 313
 314         /* Initialize expiry counter after successful mount */
 315         if (ino)
 316                 ino->last_used = jiffies;
 317
 318         spin_lock(&dentry->d_lock);
 319         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 320         spin_unlock(&dentry->d_lock);
 321         return status;
 322 }
 323
 324 /* For autofs direct mounts the follow link triggers the mount */
 325 static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
 326 {
 327         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 328         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 329         int oz_mode = autofs4_oz_mode(sbi);
 330         unsigned int lookup_type;
 331         int status;
 332
 333         DPRINTK("dentry=%p %.*s oz_mode=%d nd->flags=%d",
 334                 dentry, dentry->d_name.len, dentry->d_name.name, oz_mode,
 335                 nd->flags);
 336
 337         /* If it's our master or we shouldn't trigger a mount we're done */
 338         lookup_type = nd->flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY);
 339         if (oz_mode || !lookup_type)
 340                 goto done;
 341
 342         /* If an expire request is pending wait for it. */
 343         if (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
 344                 DPRINTK("waiting for active request %p name=%.*s",
 345                         dentry, dentry->d_name.len, dentry->d_name.name);
 346
 347                 status = autofs4_wait(sbi, dentry, NFY_NONE);
 348
 349                 DPRINTK("request done status=%d", status);
 350         }
 351
 352         /*
 353          * If the dentry contains directories then it is an
 354          * autofs multi-mount with no root mount offset. So
 355          * don't try to mount it again.
 356          */
 357         spin_lock(&dcache_lock);
 358         if (!d_mountpoint(dentry) && __simple_empty(dentry)) {
 359                 spin_unlock(&dcache_lock);
 360
 361                 status = try_to_fill_dentry(dentry, 0);
 362                 if (status)
 363                         goto out_error;
 364
 365                 /*
 366                  * The mount succeeded but if there is no root mount
 367                  * it must be an autofs multi-mount with no root offset
 368                  * so we don't need to follow the mount.
 369                  */
 370                 if (d_mountpoint(dentry)) {
 371                         if (!autofs4_follow_mount(&nd->mnt, &nd->dentry)) {
 372                                 status = -ENOENT;
 373                                 goto out_error;
 374                         }
 375                 }
 376
 377                 goto done;
 378         }
 379         spin_unlock(&dcache_lock);
 380
 381 done:
 382         return NULL;
 383
 384 out_error:
 385         path_release(nd);
 386         return ERR_PTR(status);
 387 }
 388
 389 /*
 390  * Revalidate is called on every cache lookup.  Some of those
 391  * cache lookups may actually happen while the dentry is not
 392  * yet completely filled in, and revalidate has to delay such
 393  * lookups..
 394  */
 395 static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
 396 {
 397         struct inode *dir = dentry->d_parent->d_inode;
 398         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 399         int oz_mode = autofs4_oz_mode(sbi);
 400         int flags = nd ? nd->flags : 0;
 401         int status = 1;
 402
 403         /* Pending dentry */
 404         if (autofs4_ispending(dentry)) {
 405                 /* The daemon never causes a mount to trigger */
 406                 if (oz_mode)
 407                         return 1;
 408
 409                 /*
 410                  * A zero status is success otherwise we have a
 411                  * negative error code.
 412                  */
 413                 status = try_to_fill_dentry(dentry, flags);
 414                 if (status == 0)
 415                         return 1;
 416
 417                 /*
 418                  * A status of EAGAIN here means that the dentry has gone
 419                  * away while waiting for an expire to complete. If we are
 420                  * racing with expire lookup will wait for it so this must
 421                  * be a revalidate and we need to send it to lookup.
 422                  */
 423                 if (status == -EAGAIN)
 424                         return 0;
 425
 426                 return status;
 427         }
 428
 429         /* Negative dentry.. invalidate if "old" */
 430         if (dentry->d_inode == NULL)
 431                 return 0;
 432
 433         /* Check for a non-mountpoint directory with no contents */
 434         spin_lock(&dcache_lock);
 435         if (S_ISDIR(dentry->d_inode->i_mode) &&
 436             !d_mountpoint(dentry) &&
 437             __simple_empty(dentry)) {
 438                 DPRINTK("dentry=%p %.*s, emptydir",
 439                          dentry, dentry->d_name.len, dentry->d_name.name);
 440                 spin_unlock(&dcache_lock);
 441                 /* The daemon never causes a mount to trigger */
 442                 if (oz_mode)
 443                         return 1;
 444
 445                 /*
 446                  * A zero status is success otherwise we have a
 447                  * negative error code.
 448                  */
 449                 status = try_to_fill_dentry(dentry, flags);
 450                 if (status == 0)
 451                         return 1;
 452
 453                 return status;
 454         }
 455         spin_unlock(&dcache_lock);
 456
 457         return 1;
 458 }
 459
 460 void autofs4_dentry_release(struct dentry *de)
 461 {
 462         struct autofs_info *inf;
 463
 464         DPRINTK("releasing %p", de);
 465
 466         inf = autofs4_dentry_ino(de);
 467         de->d_fsdata = NULL;
 468
 469         if (inf) {
 470                 struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb);
 471
 472                 if (sbi) {
 473                         spin_lock(&sbi->rehash_lock);
 474                         if (!list_empty(&inf->rehash))
 475                                 list_del(&inf->rehash);
 476                         spin_unlock(&sbi->rehash_lock);
 477                 }
 478
 479                 inf->dentry = NULL;
 480                 inf->inode = NULL;
 481
 482                 autofs4_free_ino(inf);
 483         }
 484 }
 485
 486 /* For dentries of directories in the root dir */
 487 static struct dentry_operations autofs4_root_dentry_operations = {
 488         .d_revalidate   = autofs4_revalidate,
 489         .d_release      = autofs4_dentry_release,
 490 };
 491
 492 /* For other dentries */
 493 static struct dentry_operations autofs4_dentry_operations = {
 494         .d_revalidate   = autofs4_revalidate,
 495         .d_release      = autofs4_dentry_release,
 496 };
 497
 498 static struct dentry *autofs4_lookup_unhashed(struct autofs_sb_info *sbi, struct dentry *parent, struct qstr *name)
 499 {
 500         unsigned int len = name->len;
 501         unsigned int hash = name->hash;
 502         const unsigned char *str = name->name;
 503         struct list_head *p, *head;
 504
 505         spin_lock(&dcache_lock);
 506         spin_lock(&sbi->rehash_lock);
 507         head = &sbi->rehash_list;
 508         list_for_each(p, head) {
 509                 struct autofs_info *ino;
 510                 struct dentry *dentry;
 511                 struct qstr *qstr;
 512
 513                 ino = list_entry(p, struct autofs_info, rehash);
 514                 dentry = ino->dentry;
 515
 516                 spin_lock(&dentry->d_lock);
 517
 518                 /* Bad luck, we've already been dentry_iput */
 519                 if (!dentry->d_inode)
 520                         goto next;
 521
 522                 qstr = &dentry->d_name;
 523
 524                 if (dentry->d_name.hash != hash)
 525                         goto next;
 526                 if (dentry->d_parent != parent)
 527                         goto next;
 528
 529                 if (qstr->len != len)
 530                         goto next;
 531                 if (memcmp(qstr->name, str, len))
 532                         goto next;
 533
 534                 if (d_unhashed(dentry)) {
 535                         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 536                         struct inode *inode = dentry->d_inode;
 537
 538                         list_del_init(&ino->rehash);
 539                         dget(dentry);
 540                         /*
 541                          * Make the rehashed dentry negative so the VFS
 542                          * behaves as it should.
 543                          */
 544                         if (inode) {
 545                                 dentry->d_inode = NULL;
 546                                 list_del_init(&dentry->d_alias);
 547                                 spin_unlock(&dentry->d_lock);
 548                                 spin_unlock(&sbi->rehash_lock);
 549                                 spin_unlock(&dcache_lock);
 550                                 iput(inode);
 551                                 return dentry;
 552                         }
 553                         spin_unlock(&dentry->d_lock);
 554                         spin_unlock(&sbi->rehash_lock);
 555                         spin_unlock(&dcache_lock);
 556                         return dentry;
 557                 }
 558 next:
 559                 spin_unlock(&dentry->d_lock);
 560         }
 561         spin_unlock(&sbi->rehash_lock);
 562         spin_unlock(&dcache_lock);
 563
 564         return NULL;
 565 }
 566
 567 /* Lookups in the root directory */
 568 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 569 {
 570         struct autofs_sb_info *sbi;
 571         struct dentry *unhashed;
 572         int oz_mode;
 573
 574         DPRINTK("name = %.*s",
 575                 dentry->d_name.len, dentry->d_name.name);
 576
 577         /* File name too long to exist */
 578         if (dentry->d_name.len > NAME_MAX)
 579                 return ERR_PTR(-ENAMETOOLONG);
 580
 581         sbi = autofs4_sbi(dir->i_sb);
 582         oz_mode = autofs4_oz_mode(sbi);
 583
 584         DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
 585                  current->pid, process_group(current), sbi->catatonic, oz_mode);
 586
 587         unhashed = autofs4_lookup_unhashed(sbi, dentry->d_parent, &dentry->d_name);
 588         if (!unhashed) {
 589                 /*
 590                  * Mark the dentry incomplete, but add it. This is needed so
 591                  * that the VFS layer knows about the dentry, and we can count
 592                  * on catching any lookups through the revalidate.
 593                  *
 594                  * Let all the hard work be done by the revalidate function that
 595                  * needs to be able to do this anyway..
 596                  *
 597                  * We need to do this before we release the directory semaphore.
 598                  */
 599                 dentry->d_op = &autofs4_root_dentry_operations;
 600
 601                 dentry->d_fsdata = NULL;
 602                 d_add(dentry, NULL);
 603         } else {
 604                 struct autofs_info *ino = autofs4_dentry_ino(unhashed);
 605                 DPRINTK("rehash %p with %p", dentry, unhashed);
 606                 /*
 607                  * If we are racing with expire the request might not
 608                  * be quite complete but the directory has been removed
 609                  * so it must have been successful, so just wait for it.
 610                  */
 611                 if (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
 612                         DPRINTK("wait for incomplete expire %p name=%.*s",
 613                                 unhashed, unhashed->d_name.len,
 614                                 unhashed->d_name.name);
 615                         autofs4_wait(sbi, unhashed, NFY_NONE);
 616                         DPRINTK("request completed");
 617                 }
 618                 d_rehash(unhashed);
 619                 dentry = unhashed;
 620         }
 621
 622         if (!oz_mode) {
 623                 spin_lock(&dentry->d_lock);
 624                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 625                 spin_unlock(&dentry->d_lock);
 626         }
 627
 628         if (dentry->d_op && dentry->d_op->d_revalidate) {
 629                 mutex_unlock(&dir->i_mutex);
 630                 (dentry->d_op->d_revalidate)(dentry, nd);
 631                 mutex_lock(&dir->i_mutex);
 632         }
 633
 634         /*
 635          * If we are still pending, check if we had to handle
 636          * a signal. If so we can force a restart..
 637          */
 638         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 639                 /* See if we were interrupted */
 640                 if (signal_pending(current)) {
 641                         sigset_t *sigset = &current->pending.signal;
 642                         if (sigismember (sigset, SIGKILL) ||
 643                             sigismember (sigset, SIGQUIT) ||
 644                             sigismember (sigset, SIGINT)) {
 645                             if (unhashed)
 646                                 dput(unhashed);
 647                             return ERR_PTR(-ERESTARTNOINTR);
 648                         }
 649                 }
 650                 spin_lock(&dentry->d_lock);
 651                 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 652                 spin_unlock(&dentry->d_lock);
 653         }
 654
 655         /*
 656          * If this dentry is unhashed, then we shouldn't honour this
 657          * lookup.  Returning ENOENT here doesn't do the right thing
 658          * for all system calls, but it should be OK for the operations
 659          * we permit from an autofs.
 660          */
 661         if (dentry->d_inode && d_unhashed(dentry)) {
 662                 /*
 663                  * A user space application can (and has done in the past)
 664                  * remove and re-create this directory during the callback.
 665                  * This can leave us with an unhashed dentry, but a
 666                  * successful mount!  So we need to perform another
 667                  * cached lookup in case the dentry now exists.
 668                  */
 669                 struct dentry *parent = dentry->d_parent;
 670                 struct dentry *new = d_lookup(parent, &dentry->d_name);
 671                 if (new != NULL)
 672                         dentry = new;
 673                 else
 674                         dentry = ERR_PTR(-ENOENT);
 675
 676                 if (unhashed)
 677                         dput(unhashed);
 678
 679                 return dentry;
 680         }
 681
 682         if (unhashed)
 683                 return dentry;
 684
 685         return NULL;
 686 }
 687
 688 static int autofs4_dir_symlink(struct inode *dir,
 689                                struct dentry *dentry,
 690                                const char *symname)
 691 {
 692         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 693         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 694         struct autofs_info *p_ino;
 695         struct inode *inode;
 696         char *cp;
 697
 698         DPRINTK("%s <- %.*s", symname,
 699                 dentry->d_name.len, dentry->d_name.name);
 700
 701         if (!autofs4_oz_mode(sbi))
 702                 return -EACCES;
 703
 704         ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
 705         if (ino == NULL)
 706                 return -ENOSPC;
 707
 708         ino->size = strlen(symname);
 709         ino->u.symlink = cp = kmalloc(ino->size + 1, GFP_KERNEL);
 710
 711         if (cp == NULL) {
 712                 kfree(ino);
 713                 return -ENOSPC;
 714         }
 715
 716         strcpy(cp, symname);
 717
 718         inode = autofs4_get_inode(dir->i_sb, ino);
 719         d_instantiate(dentry, inode);
 720
 721         if (dir == dir->i_sb->s_root->d_inode)
 722                 dentry->d_op = &autofs4_root_dentry_operations;
 723         else
 724                 dentry->d_op = &autofs4_dentry_operations;
 725
 726         dentry->d_fsdata = ino;
 727         ino->dentry = dget(dentry);
 728         atomic_inc(&ino->count);
 729         p_ino = autofs4_dentry_ino(dentry->d_parent);
 730         if (p_ino && dentry->d_parent != dentry)
 731                 atomic_inc(&p_ino->count);
 732         ino->inode = inode;
 733
 734         dir->i_mtime = CURRENT_TIME;
 735
 736         return 0;
 737 }
 738
 739 /*
 740  * NOTE!
 741  *
 742  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 743  * that the file no longer exists. However, doing that means that the
 744  * VFS layer can turn the dentry into a negative dentry.  We don't want
 745  * this, because the unlink is probably the result of an expire.
 746  * We simply d_drop it and add it to a rehash candidates list in the
 747  * super block, which allows the dentry lookup to reuse it retaining
 748  * the flags, such as expire in progress, in case we're racing with expire.
 749  *
 750  * If a process is blocked on the dentry waiting for the expire to finish,
 751  * it will invalidate the dentry and try to mount with a new one.
 752  *
 753  * Also see autofs4_dir_rmdir()..
 754  */
 755 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
 756 {
 757         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 758         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 759         struct autofs_info *p_ino;
 760
 761         /* This allows root to remove symlinks */
 762         if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
 763                 return -EACCES;
 764
 765         if (atomic_dec_and_test(&ino->count)) {
 766                 p_ino = autofs4_dentry_ino(dentry->d_parent);
 767                 if (p_ino && dentry->d_parent != dentry)
 768                         atomic_dec(&p_ino->count);
 769         }
 770         dput(ino->dentry);
 771
 772         dentry->d_inode->i_size = 0;
 773         clear_nlink(dentry->d_inode);
 774
 775         dir->i_mtime = CURRENT_TIME;
 776
 777         spin_lock(&dcache_lock);
 778         spin_lock(&sbi->rehash_lock);
 779         list_add(&ino->rehash, &sbi->rehash_list);
 780         spin_unlock(&sbi->rehash_lock);
 781         spin_lock(&dentry->d_lock);
 782         __d_drop(dentry);
 783         spin_unlock(&dentry->d_lock);
 784         spin_unlock(&dcache_lock);
 785
 786         return 0;
 787 }
 788
 789 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
 790 {
 791         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 792         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 793         struct autofs_info *p_ino;
 794
 795         DPRINTK("dentry %p, removing %.*s",
 796                 dentry, dentry->d_name.len, dentry->d_name.name);
 797
 798         if (!autofs4_oz_mode(sbi))
 799                 return -EACCES;
 800
 801         spin_lock(&dcache_lock);
 802         if (!list_empty(&dentry->d_subdirs)) {
 803                 spin_unlock(&dcache_lock);
 804                 return -ENOTEMPTY;
 805         }
 806         spin_lock(&sbi->rehash_lock);
 807         list_add(&ino->rehash, &sbi->rehash_list);
 808         spin_unlock(&sbi->rehash_lock);
 809         spin_lock(&dentry->d_lock);
 810         __d_drop(dentry);
 811         spin_unlock(&dentry->d_lock);
 812         spin_unlock(&dcache_lock);
 813
 814         if (atomic_dec_and_test(&ino->count)) {
 815                 p_ino = autofs4_dentry_ino(dentry->d_parent);
 816                 if (p_ino && dentry->d_parent != dentry)
 817                         atomic_dec(&p_ino->count);
 818         }
 819         dput(ino->dentry);
 820         dentry->d_inode->i_size = 0;
 821         clear_nlink(dentry->d_inode);
 822
 823         if (dir->i_nlink)
 824                 drop_nlink(dir);
 825
 826         return 0;
 827 }
 828
 829 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 830 {
 831         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 832         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 833         struct autofs_info *p_ino;
 834         struct inode *inode;
 835
 836         if (!autofs4_oz_mode(sbi))
 837                 return -EACCES;
 838
 839         DPRINTK("dentry %p, creating %.*s",
 840                 dentry, dentry->d_name.len, dentry->d_name.name);
 841
 842         ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
 843         if (ino == NULL)
 844                 return -ENOSPC;
 845
 846         inode = autofs4_get_inode(dir->i_sb, ino);
 847         d_instantiate(dentry, inode);
 848
 849         if (dir == dir->i_sb->s_root->d_inode)
 850                 dentry->d_op = &autofs4_root_dentry_operations;
 851         else
 852                 dentry->d_op = &autofs4_dentry_operations;
 853
 854         dentry->d_fsdata = ino;
 855         ino->dentry = dget(dentry);
 856         atomic_inc(&ino->count);
 857         p_ino = autofs4_dentry_ino(dentry->d_parent);
 858         if (p_ino && dentry->d_parent != dentry)
 859                 atomic_inc(&p_ino->count);
 860         ino->inode = inode;
 861         inc_nlink(dir);
 862         dir->i_mtime = CURRENT_TIME;
 863
 864         return 0;
 865 }
 866
 867 /* Get/set timeout ioctl() operation */
 868 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
 869                                          unsigned long __user *p)
 870 {
 871         int rv;
 872         unsigned long ntimeout;
 873
 874         if ((rv = get_user(ntimeout, p)) ||
 875              (rv = put_user(sbi->exp_timeout/HZ, p)))
 876                 return rv;
 877
 878         if (ntimeout > ULONG_MAX/HZ)
 879                 sbi->exp_timeout = 0;
 880         else
 881                 sbi->exp_timeout = ntimeout * HZ;
 882
 883         return 0;
 884 }
 885
 886 /* Return protocol version */
 887 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
 888 {
 889         return put_user(sbi->version, p);
 890 }
 891
 892 /* Return protocol sub version */
 893 static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
 894 {
 895         return put_user(sbi->sub_version, p);
 896 }
 897
 898 /*
 899  * Tells the daemon whether we need to reghost or not. Also, clears
 900  * the reghost_needed flag.
 901  */
 902 static inline int autofs4_ask_reghost(struct autofs_sb_info *sbi, int __user *p)
 903 {
 904         int status;
 905
 906         DPRINTK("returning %d", sbi->needs_reghost);
 907
 908         status = put_user(sbi->needs_reghost, p);
 909         if (status)
 910                 return status;
 911
 912         sbi->needs_reghost = 0;
 913         return 0;
 914 }
 915
 916 /*
 917  * Enable / Disable reghosting ioctl() operation
 918  */
 919 static inline int autofs4_toggle_reghost(struct autofs_sb_info *sbi, int __user *p)
 920 {
 921         int status;
 922         int val;
 923
 924         status = get_user(val, p);
 925
 926         DPRINTK("reghost = %d", val);
 927
 928         if (status)
 929                 return status;
 930
 931         /* turn on/off reghosting, with the val */
 932         sbi->reghost_enabled = val;
 933         return 0;
 934 }
 935
 936 /*
 937 * Tells the daemon whether it can umount the autofs mount.
 938 */
 939 static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
 940 {
 941         int status = 0;
 942
 943         if (may_umount(mnt))
 944                 status = 1;
 945
 946         DPRINTK("returning %d", status);
 947
 948         status = put_user(status, p);
 949
 950         return status;
 951 }
 952
 953 /* Identify autofs4_dentries - this is so we can tell if there's
 954    an extra dentry refcount or not.  We only hold a refcount on the
 955    dentry if its non-negative (ie, d_inode != NULL)
 956 */
 957 int is_autofs4_dentry(struct dentry *dentry)
 958 {
 959         return dentry && dentry->d_inode &&
 960                 (dentry->d_op == &autofs4_root_dentry_operations ||
 961                  dentry->d_op == &autofs4_dentry_operations) &&
 962                 dentry->d_fsdata != NULL;
 963 }
 964
 965 /*
 966  * ioctl()'s on the root directory is the chief method for the daemon to
 967  * generate kernel reactions
 968  */
 969 static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
 970                              unsigned int cmd, unsigned long arg)
 971 {
 972         struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
 973         void __user *p = (void __user *)arg;
 974
 975         DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
 976                 cmd,arg,sbi,process_group(current));
 977
 978         if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
 979              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
 980                 return -ENOTTY;
 981
 982         if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
 983                 return -EPERM;
 984
 985         switch(cmd) {
 986         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
 987                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
 988         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
 989                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
 990         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
 991                 autofs4_catatonic_mode(sbi);
 992                 return 0;
 993         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
 994                 return autofs4_get_protover(sbi, p);
 995         case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
 996                 return autofs4_get_protosubver(sbi, p);
 997         case AUTOFS_IOC_SETTIMEOUT:
 998                 return autofs4_get_set_timeout(sbi, p);
 999
1000         case AUTOFS_IOC_TOGGLEREGHOST:
1001                 return autofs4_toggle_reghost(sbi, p);
1002         case AUTOFS_IOC_ASKREGHOST:
1003                 return autofs4_ask_reghost(sbi, p);
1004
1005         case AUTOFS_IOC_ASKUMOUNT:
1006                 return autofs4_ask_umount(filp->f_path.mnt, p);
1007
1008         /* return a single thing to expire */
1009         case AUTOFS_IOC_EXPIRE:
1010                 return autofs4_expire_run(inode->i_sb,filp->f_path.mnt,sbi, p);
1011         /* same as above, but can send multiple expires through pipe */
1012         case AUTOFS_IOC_EXPIRE_MULTI:
1013                 return autofs4_expire_multi(inode->i_sb,filp->f_path.mnt,sbi, p);
1014
1015         default:
1016                 return -ENOSYS;
1017         }
1018 }