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->path.mnt,
 372                                                   &nd->path.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_put(&nd->path);
 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, task_pgrp_nr(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 don't hash it. We do this
 592                  * to serialize our inode creation operations (symlink and
 593                  * mkdir) which prevents deadlock during the callback to
 594                  * the daemon. Subsequent user space lookups for the same
 595                  * dentry are placed on the wait queue while the daemon
 596                  * itself is allowed passage unresticted so the create
 597                  * operation itself can then hash the dentry. Finally,
 598                  * we check for the hashed dentry and return the newly
 599                  * hashed dentry.
 600                  */
 601                 dentry->d_op = &autofs4_root_dentry_operations;
 602
 603                 dentry->d_fsdata = NULL;
 604                 d_instantiate(dentry, NULL);
 605         } else {
 606                 struct autofs_info *ino = autofs4_dentry_ino(unhashed);
 607                 DPRINTK("rehash %p with %p", dentry, unhashed);
 608                 /*
 609                  * If we are racing with expire the request might not
 610                  * be quite complete but the directory has been removed
 611                  * so it must have been successful, so just wait for it.
 612                  * We need to ensure the AUTOFS_INF_EXPIRING flag is clear
 613                  * before continuing as revalidate may fail when calling
 614                  * try_to_fill_dentry (returning EAGAIN) if we don't.
 615                  */
 616                 while (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
 617                         DPRINTK("wait for incomplete expire %p name=%.*s",
 618                                 unhashed, unhashed->d_name.len,
 619                                 unhashed->d_name.name);
 620                         autofs4_wait(sbi, unhashed, NFY_NONE);
 621                         DPRINTK("request completed");
 622                 }
 623                 dentry = unhashed;
 624         }
 625
 626         if (!oz_mode) {
 627                 spin_lock(&dentry->d_lock);
 628                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 629                 spin_unlock(&dentry->d_lock);
 630         }
 631
 632         if (dentry->d_op && dentry->d_op->d_revalidate) {
 633                 mutex_unlock(&dir->i_mutex);
 634                 (dentry->d_op->d_revalidate)(dentry, nd);
 635                 mutex_lock(&dir->i_mutex);
 636         }
 637
 638         /*
 639          * If we are still pending, check if we had to handle
 640          * a signal. If so we can force a restart..
 641          */
 642         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 643                 /* See if we were interrupted */
 644                 if (signal_pending(current)) {
 645                         sigset_t *sigset = &current->pending.signal;
 646                         if (sigismember (sigset, SIGKILL) ||
 647                             sigismember (sigset, SIGQUIT) ||
 648                             sigismember (sigset, SIGINT)) {
 649                             if (unhashed)
 650                                 dput(unhashed);
 651                             return ERR_PTR(-ERESTARTNOINTR);
 652                         }
 653                 }
 654                 spin_lock(&dentry->d_lock);
 655                 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 656                 spin_unlock(&dentry->d_lock);
 657         }
 658
 659         /*
 660          * If this dentry is unhashed, then we shouldn't honour this
 661          * lookup.  Returning ENOENT here doesn't do the right thing
 662          * for all system calls, but it should be OK for the operations
 663          * we permit from an autofs.
 664          */
 665         if (!oz_mode && d_unhashed(dentry)) {
 666                 /*
 667                  * A user space application can (and has done in the past)
 668                  * remove and re-create this directory during the callback.
 669                  * This can leave us with an unhashed dentry, but a
 670                  * successful mount!  So we need to perform another
 671                  * cached lookup in case the dentry now exists.
 672                  */
 673                 struct dentry *parent = dentry->d_parent;
 674                 struct dentry *new = d_lookup(parent, &dentry->d_name);
 675                 if (new != NULL)
 676                         dentry = new;
 677                 else
 678                         dentry = ERR_PTR(-ENOENT);
 679
 680                 if (unhashed)
 681                         dput(unhashed);
 682
 683                 return dentry;
 684         }
 685
 686         if (unhashed)
 687                 return dentry;
 688
 689         return NULL;
 690 }
 691
 692 static int autofs4_dir_symlink(struct inode *dir,
 693                                struct dentry *dentry,
 694                                const char *symname)
 695 {
 696         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 697         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 698         struct autofs_info *p_ino;
 699         struct inode *inode;
 700         char *cp;
 701
 702         DPRINTK("%s <- %.*s", symname,
 703                 dentry->d_name.len, dentry->d_name.name);
 704
 705         if (!autofs4_oz_mode(sbi))
 706                 return -EACCES;
 707
 708         ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
 709         if (ino == NULL)
 710                 return -ENOSPC;
 711
 712         ino->size = strlen(symname);
 713         ino->u.symlink = cp = kmalloc(ino->size + 1, GFP_KERNEL);
 714
 715         if (cp == NULL) {
 716                 kfree(ino);
 717                 return -ENOSPC;
 718         }
 719
 720         strcpy(cp, symname);
 721
 722         inode = autofs4_get_inode(dir->i_sb, ino);
 723         d_add(dentry, inode);
 724
 725         if (dir == dir->i_sb->s_root->d_inode)
 726                 dentry->d_op = &autofs4_root_dentry_operations;
 727         else
 728                 dentry->d_op = &autofs4_dentry_operations;
 729
 730         dentry->d_fsdata = ino;
 731         ino->dentry = dget(dentry);
 732         atomic_inc(&ino->count);
 733         p_ino = autofs4_dentry_ino(dentry->d_parent);
 734         if (p_ino && dentry->d_parent != dentry)
 735                 atomic_inc(&p_ino->count);
 736         ino->inode = inode;
 737
 738         dir->i_mtime = CURRENT_TIME;
 739
 740         return 0;
 741 }
 742
 743 /*
 744  * NOTE!
 745  *
 746  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 747  * that the file no longer exists. However, doing that means that the
 748  * VFS layer can turn the dentry into a negative dentry.  We don't want
 749  * this, because the unlink is probably the result of an expire.
 750  * We simply d_drop it and add it to a rehash candidates list in the
 751  * super block, which allows the dentry lookup to reuse it retaining
 752  * the flags, such as expire in progress, in case we're racing with expire.
 753  *
 754  * If a process is blocked on the dentry waiting for the expire to finish,
 755  * it will invalidate the dentry and try to mount with a new one.
 756  *
 757  * Also see autofs4_dir_rmdir()..
 758  */
 759 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
 760 {
 761         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 762         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 763         struct autofs_info *p_ino;
 764
 765         /* This allows root to remove symlinks */
 766         if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
 767                 return -EACCES;
 768
 769         if (atomic_dec_and_test(&ino->count)) {
 770                 p_ino = autofs4_dentry_ino(dentry->d_parent);
 771                 if (p_ino && dentry->d_parent != dentry)
 772                         atomic_dec(&p_ino->count);
 773         }
 774         dput(ino->dentry);
 775
 776         dentry->d_inode->i_size = 0;
 777         clear_nlink(dentry->d_inode);
 778
 779         dir->i_mtime = CURRENT_TIME;
 780
 781         spin_lock(&dcache_lock);
 782         spin_lock(&sbi->rehash_lock);
 783         list_add(&ino->rehash, &sbi->rehash_list);
 784         spin_unlock(&sbi->rehash_lock);
 785         spin_lock(&dentry->d_lock);
 786         __d_drop(dentry);
 787         spin_unlock(&dentry->d_lock);
 788         spin_unlock(&dcache_lock);
 789
 790         return 0;
 791 }
 792
 793 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
 794 {
 795         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 796         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 797         struct autofs_info *p_ino;
 798
 799         DPRINTK("dentry %p, removing %.*s",
 800                 dentry, dentry->d_name.len, dentry->d_name.name);
 801
 802         if (!autofs4_oz_mode(sbi))
 803                 return -EACCES;
 804
 805         spin_lock(&dcache_lock);
 806         if (!list_empty(&dentry->d_subdirs)) {
 807                 spin_unlock(&dcache_lock);
 808                 return -ENOTEMPTY;
 809         }
 810         spin_lock(&sbi->rehash_lock);
 811         list_add(&ino->rehash, &sbi->rehash_list);
 812         spin_unlock(&sbi->rehash_lock);
 813         spin_lock(&dentry->d_lock);
 814         __d_drop(dentry);
 815         spin_unlock(&dentry->d_lock);
 816         spin_unlock(&dcache_lock);
 817
 818         if (atomic_dec_and_test(&ino->count)) {
 819                 p_ino = autofs4_dentry_ino(dentry->d_parent);
 820                 if (p_ino && dentry->d_parent != dentry)
 821                         atomic_dec(&p_ino->count);
 822         }
 823         dput(ino->dentry);
 824         dentry->d_inode->i_size = 0;
 825         clear_nlink(dentry->d_inode);
 826
 827         if (dir->i_nlink)
 828                 drop_nlink(dir);
 829
 830         return 0;
 831 }
 832
 833 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 834 {
 835         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 836         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 837         struct autofs_info *p_ino;
 838         struct inode *inode;
 839
 840         if (!autofs4_oz_mode(sbi))
 841                 return -EACCES;
 842
 843         DPRINTK("dentry %p, creating %.*s",
 844                 dentry, dentry->d_name.len, dentry->d_name.name);
 845
 846         ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
 847         if (ino == NULL)
 848                 return -ENOSPC;
 849
 850         inode = autofs4_get_inode(dir->i_sb, ino);
 851         d_add(dentry, inode);
 852
 853         if (dir == dir->i_sb->s_root->d_inode)
 854                 dentry->d_op = &autofs4_root_dentry_operations;
 855         else
 856                 dentry->d_op = &autofs4_dentry_operations;
 857
 858         dentry->d_fsdata = ino;
 859         ino->dentry = dget(dentry);
 860         atomic_inc(&ino->count);
 861         p_ino = autofs4_dentry_ino(dentry->d_parent);
 862         if (p_ino && dentry->d_parent != dentry)
 863                 atomic_inc(&p_ino->count);
 864         ino->inode = inode;
 865         inc_nlink(dir);
 866         dir->i_mtime = CURRENT_TIME;
 867
 868         return 0;
 869 }
 870
 871 /* Get/set timeout ioctl() operation */
 872 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
 873                                          unsigned long __user *p)
 874 {
 875         int rv;
 876         unsigned long ntimeout;
 877
 878         if ((rv = get_user(ntimeout, p)) ||
 879              (rv = put_user(sbi->exp_timeout/HZ, p)))
 880                 return rv;
 881
 882         if (ntimeout > ULONG_MAX/HZ)
 883                 sbi->exp_timeout = 0;
 884         else
 885                 sbi->exp_timeout = ntimeout * HZ;
 886
 887         return 0;
 888 }
 889
 890 /* Return protocol version */
 891 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
 892 {
 893         return put_user(sbi->version, p);
 894 }
 895
 896 /* Return protocol sub version */
 897 static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
 898 {
 899         return put_user(sbi->sub_version, p);
 900 }
 901
 902 /*
 903  * Tells the daemon whether we need to reghost or not. Also, clears
 904  * the reghost_needed flag.
 905  */
 906 static inline int autofs4_ask_reghost(struct autofs_sb_info *sbi, int __user *p)
 907 {
 908         int status;
 909
 910         DPRINTK("returning %d", sbi->needs_reghost);
 911
 912         status = put_user(sbi->needs_reghost, p);
 913         if (status)
 914                 return status;
 915
 916         sbi->needs_reghost = 0;
 917         return 0;
 918 }
 919
 920 /*
 921  * Enable / Disable reghosting ioctl() operation
 922  */
 923 static inline int autofs4_toggle_reghost(struct autofs_sb_info *sbi, int __user *p)
 924 {
 925         int status;
 926         int val;
 927
 928         status = get_user(val, p);
 929
 930         DPRINTK("reghost = %d", val);
 931
 932         if (status)
 933                 return status;
 934
 935         /* turn on/off reghosting, with the val */
 936         sbi->reghost_enabled = val;
 937         return 0;
 938 }
 939
 940 /*
 941 * Tells the daemon whether it can umount the autofs mount.
 942 */
 943 static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
 944 {
 945         int status = 0;
 946
 947         if (may_umount(mnt))
 948                 status = 1;
 949
 950         DPRINTK("returning %d", status);
 951
 952         status = put_user(status, p);
 953
 954         return status;
 955 }
 956
 957 /* Identify autofs4_dentries - this is so we can tell if there's
 958    an extra dentry refcount or not.  We only hold a refcount on the
 959    dentry if its non-negative (ie, d_inode != NULL)
 960 */
 961 int is_autofs4_dentry(struct dentry *dentry)
 962 {
 963         return dentry && dentry->d_inode &&
 964                 (dentry->d_op == &autofs4_root_dentry_operations ||
 965                  dentry->d_op == &autofs4_dentry_operations) &&
 966                 dentry->d_fsdata != NULL;
 967 }
 968
 969 /*
 970  * ioctl()'s on the root directory is the chief method for the daemon to
 971  * generate kernel reactions
 972  */
 973 static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
 974                              unsigned int cmd, unsigned long arg)
 975 {
 976         struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
 977         void __user *p = (void __user *)arg;
 978
 979         DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
 980                 cmd,arg,sbi,task_pgrp_nr(current));
 981
 982         if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
 983              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
 984                 return -ENOTTY;
 985
 986         if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
 987                 return -EPERM;
 988
 989         switch(cmd) {
 990         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
 991                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
 992         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
 993                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
 994         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
 995                 autofs4_catatonic_mode(sbi);
 996                 return 0;
 997         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
 998                 return autofs4_get_protover(sbi, p);
 999         case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
1000                 return autofs4_get_protosubver(sbi, p);
1001         case AUTOFS_IOC_SETTIMEOUT:
1002                 return autofs4_get_set_timeout(sbi, p);
1003
1004         case AUTOFS_IOC_TOGGLEREGHOST:
1005                 return autofs4_toggle_reghost(sbi, p);
1006         case AUTOFS_IOC_ASKREGHOST:
1007                 return autofs4_ask_reghost(sbi, p);
1008
1009         case AUTOFS_IOC_ASKUMOUNT:
1010                 return autofs4_ask_umount(filp->f_path.mnt, p);
1011
1012         /* return a single thing to expire */
1013         case AUTOFS_IOC_EXPIRE:
1014                 return autofs4_expire_run(inode->i_sb,filp->f_path.mnt,sbi, p);
1015         /* same as above, but can send multiple expires through pipe */
1016         case AUTOFS_IOC_EXPIRE_MULTI:
1017                 return autofs4_expire_multi(inode->i_sb,filp->f_path.mnt,sbi, p);
1018
1019         default:
1020                 return -ENOSYS;
1021         }
1022 }