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 path fp_path = { .dentry = dentry, .mnt = mnt };
 150
 151                 path_get(&fp_path);
 152
 153                 if (!autofs4_follow_mount(&fp_path.mnt, &fp_path.dentry)) {
 154                         path_put(&fp_path);
 155                         dcache_dir_close(inode, file);
 156                         goto out;
 157                 }
 158
 159                 fp = dentry_open(fp_path.dentry, fp_path.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;
 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
 322         return 0;
 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->path.mnt,
 373                                                   &nd->path.dentry)) {
 374                                 status = -ENOENT;
 375                                 goto out_error;
 376                         }
 377                 }
 378
 379                 goto done;
 380         }
 381         spin_unlock(&dcache_lock);
 382
 383 done:
 384         return NULL;
 385
 386 out_error:
 387         path_put(&nd->path);
 388         return ERR_PTR(status);
 389 }
 390
 391 /*
 392  * Revalidate is called on every cache lookup.  Some of those
 393  * cache lookups may actually happen while the dentry is not
 394  * yet completely filled in, and revalidate has to delay such
 395  * lookups..
 396  */
 397 static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
 398 {
 399         struct inode *dir = dentry->d_parent->d_inode;
 400         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 401         int oz_mode = autofs4_oz_mode(sbi);
 402         int flags = nd ? nd->flags : 0;
 403         int status = 1;
 404
 405         /* Pending dentry */
 406         if (autofs4_ispending(dentry)) {
 407                 /* The daemon never causes a mount to trigger */
 408                 if (oz_mode)
 409                         return 1;
 410
 411                 /*
 412                  * A zero status is success otherwise we have a
 413                  * negative error code.
 414                  */
 415                 status = try_to_fill_dentry(dentry, flags);
 416                 if (status == 0)
 417                         return 1;
 418
 419                 /*
 420                  * A status of EAGAIN here means that the dentry has gone
 421                  * away while waiting for an expire to complete. If we are
 422                  * racing with expire lookup will wait for it so this must
 423                  * be a revalidate and we need to send it to lookup.
 424                  */
 425                 if (status == -EAGAIN)
 426                         return 0;
 427
 428                 return status;
 429         }
 430
 431         /* Negative dentry.. invalidate if "old" */
 432         if (dentry->d_inode == NULL)
 433                 return 0;
 434
 435         /* Check for a non-mountpoint directory with no contents */
 436         spin_lock(&dcache_lock);
 437         if (S_ISDIR(dentry->d_inode->i_mode) &&
 438             !d_mountpoint(dentry) &&
 439             __simple_empty(dentry)) {
 440                 DPRINTK("dentry=%p %.*s, emptydir",
 441                          dentry, dentry->d_name.len, dentry->d_name.name);
 442                 spin_unlock(&dcache_lock);
 443                 /* The daemon never causes a mount to trigger */
 444                 if (oz_mode)
 445                         return 1;
 446
 447                 /*
 448                  * A zero status is success otherwise we have a
 449                  * negative error code.
 450                  */
 451                 status = try_to_fill_dentry(dentry, flags);
 452                 if (status == 0)
 453                         return 1;
 454
 455                 return status;
 456         }
 457         spin_unlock(&dcache_lock);
 458
 459         return 1;
 460 }
 461
 462 void autofs4_dentry_release(struct dentry *de)
 463 {
 464         struct autofs_info *inf;
 465
 466         DPRINTK("releasing %p", de);
 467
 468         inf = autofs4_dentry_ino(de);
 469         de->d_fsdata = NULL;
 470
 471         if (inf) {
 472                 struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb);
 473
 474                 if (sbi) {
 475                         spin_lock(&sbi->lookup_lock);
 476                         if (!list_empty(&inf->active))
 477                                 list_del(&inf->active);
 478                         if (!list_empty(&inf->expiring))
 479                                 list_del(&inf->expiring);
 480                         spin_unlock(&sbi->lookup_lock);
 481                 }
 482
 483                 inf->dentry = NULL;
 484                 inf->inode = NULL;
 485
 486                 autofs4_free_ino(inf);
 487         }
 488 }
 489
 490 /* For dentries of directories in the root dir */
 491 static struct dentry_operations autofs4_root_dentry_operations = {
 492         .d_revalidate   = autofs4_revalidate,
 493         .d_release      = autofs4_dentry_release,
 494 };
 495
 496 /* For other dentries */
 497 static struct dentry_operations autofs4_dentry_operations = {
 498         .d_revalidate   = autofs4_revalidate,
 499         .d_release      = autofs4_dentry_release,
 500 };
 501
 502 static struct dentry *autofs4_lookup_active(struct autofs_sb_info *sbi, struct dentry *parent, struct qstr *name)
 503 {
 504         unsigned int len = name->len;
 505         unsigned int hash = name->hash;
 506         const unsigned char *str = name->name;
 507         struct list_head *p, *head;
 508
 509         spin_lock(&dcache_lock);
 510         spin_lock(&sbi->lookup_lock);
 511         head = &sbi->active_list;
 512         list_for_each(p, head) {
 513                 struct autofs_info *ino;
 514                 struct dentry *dentry;
 515                 struct qstr *qstr;
 516
 517                 ino = list_entry(p, struct autofs_info, active);
 518                 dentry = ino->dentry;
 519
 520                 spin_lock(&dentry->d_lock);
 521
 522                 /* Already gone? */
 523                 if (atomic_read(&dentry->d_count) == 0)
 524                         goto next;
 525
 526                 qstr = &dentry->d_name;
 527
 528                 if (dentry->d_name.hash != hash)
 529                         goto next;
 530                 if (dentry->d_parent != parent)
 531                         goto next;
 532
 533                 if (qstr->len != len)
 534                         goto next;
 535                 if (memcmp(qstr->name, str, len))
 536                         goto next;
 537
 538                 if (d_unhashed(dentry)) {
 539                         dget(dentry);
 540                         spin_unlock(&dentry->d_lock);
 541                         spin_unlock(&sbi->lookup_lock);
 542                         spin_unlock(&dcache_lock);
 543                         return dentry;
 544                 }
 545 next:
 546                 spin_unlock(&dentry->d_lock);
 547         }
 548         spin_unlock(&sbi->lookup_lock);
 549         spin_unlock(&dcache_lock);
 550
 551         return NULL;
 552 }
 553
 554 static struct dentry *autofs4_lookup_expiring(struct autofs_sb_info *sbi, struct dentry *parent, struct qstr *name)
 555 {
 556         unsigned int len = name->len;
 557         unsigned int hash = name->hash;
 558         const unsigned char *str = name->name;
 559         struct list_head *p, *head;
 560
 561         spin_lock(&dcache_lock);
 562         spin_lock(&sbi->lookup_lock);
 563         head = &sbi->expiring_list;
 564         list_for_each(p, head) {
 565                 struct autofs_info *ino;
 566                 struct dentry *dentry;
 567                 struct qstr *qstr;
 568
 569                 ino = list_entry(p, struct autofs_info, expiring);
 570                 dentry = ino->dentry;
 571
 572                 spin_lock(&dentry->d_lock);
 573
 574                 /* Bad luck, we've already been dentry_iput */
 575                 if (!dentry->d_inode)
 576                         goto next;
 577
 578                 qstr = &dentry->d_name;
 579
 580                 if (dentry->d_name.hash != hash)
 581                         goto next;
 582                 if (dentry->d_parent != parent)
 583                         goto next;
 584
 585                 if (qstr->len != len)
 586                         goto next;
 587                 if (memcmp(qstr->name, str, len))
 588                         goto next;
 589
 590                 if (d_unhashed(dentry)) {
 591                         dget(dentry);
 592                         spin_unlock(&dentry->d_lock);
 593                         spin_unlock(&sbi->lookup_lock);
 594                         spin_unlock(&dcache_lock);
 595                         return dentry;
 596                 }
 597 next:
 598                 spin_unlock(&dentry->d_lock);
 599         }
 600         spin_unlock(&sbi->lookup_lock);
 601         spin_unlock(&dcache_lock);
 602
 603         return NULL;
 604 }
 605
 606 /* Lookups in the root directory */
 607 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 608 {
 609         struct autofs_sb_info *sbi;
 610         struct autofs_info *ino;
 611         struct dentry *expiring, *unhashed;
 612         int oz_mode;
 613
 614         DPRINTK("name = %.*s",
 615                 dentry->d_name.len, dentry->d_name.name);
 616
 617         /* File name too long to exist */
 618         if (dentry->d_name.len > NAME_MAX)
 619                 return ERR_PTR(-ENAMETOOLONG);
 620
 621         sbi = autofs4_sbi(dir->i_sb);
 622         oz_mode = autofs4_oz_mode(sbi);
 623
 624         DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
 625                  current->pid, task_pgrp_nr(current), sbi->catatonic, oz_mode);
 626
 627         expiring = autofs4_lookup_expiring(sbi, dentry->d_parent, &dentry->d_name);
 628         if (expiring) {
 629                 /*
 630                  * If we are racing with expire the request might not
 631                  * be quite complete but the directory has been removed
 632                  * so it must have been successful, so just wait for it.
 633                  */
 634                 ino = autofs4_dentry_ino(expiring);
 635                 while (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
 636                         DPRINTK("wait for incomplete expire %p name=%.*s",
 637                                 expiring, expiring->d_name.len,
 638                                 expiring->d_name.name);
 639                         autofs4_wait(sbi, expiring, NFY_NONE);
 640                         DPRINTK("request completed");
 641                 }
 642                 spin_lock(&sbi->lookup_lock);
 643                 if (!list_empty(&ino->expiring))
 644                         list_del_init(&ino->expiring);
 645                 spin_unlock(&sbi->lookup_lock);
 646                 dput(expiring);
 647         }
 648
 649         unhashed = autofs4_lookup_active(sbi, dentry->d_parent, &dentry->d_name);
 650         if (unhashed)
 651                 dentry = unhashed;
 652         else {
 653                 /*
 654                  * Mark the dentry incomplete but don't hash it. We do this
 655                  * to serialize our inode creation operations (symlink and
 656                  * mkdir) which prevents deadlock during the callback to
 657                  * the daemon. Subsequent user space lookups for the same
 658                  * dentry are placed on the wait queue while the daemon
 659                  * itself is allowed passage unresticted so the create
 660                  * operation itself can then hash the dentry. Finally,
 661                  * we check for the hashed dentry and return the newly
 662                  * hashed dentry.
 663                  */
 664                 dentry->d_op = &autofs4_root_dentry_operations;
 665
 666                 /*
 667                  * And we need to ensure that the same dentry is used for
 668                  * all following lookup calls until it is hashed so that
 669                  * the dentry flags are persistent throughout the request.
 670                  */
 671                 ino = autofs4_init_ino(NULL, sbi, 0555);
 672                 if (!ino)
 673                         return ERR_PTR(-ENOMEM);
 674
 675                 dentry->d_fsdata = ino;
 676                 ino->dentry = dentry;
 677
 678                 spin_lock(&sbi->lookup_lock);
 679                 list_add(&ino->active, &sbi->active_list);
 680                 spin_unlock(&sbi->lookup_lock);
 681
 682                 d_instantiate(dentry, NULL);
 683         }
 684
 685         if (!oz_mode) {
 686                 spin_lock(&dentry->d_lock);
 687                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 688                 spin_unlock(&dentry->d_lock);
 689         }
 690
 691         if (dentry->d_op && dentry->d_op->d_revalidate) {
 692                 mutex_unlock(&dir->i_mutex);
 693                 (dentry->d_op->d_revalidate)(dentry, nd);
 694                 mutex_lock(&dir->i_mutex);
 695         }
 696
 697         /*
 698          * If we are still pending, check if we had to handle
 699          * a signal. If so we can force a restart..
 700          */
 701         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 702                 /* See if we were interrupted */
 703                 if (signal_pending(current)) {
 704                         sigset_t *sigset = &current->pending.signal;
 705                         if (sigismember (sigset, SIGKILL) ||
 706                             sigismember (sigset, SIGQUIT) ||
 707                             sigismember (sigset, SIGINT)) {
 708                             if (unhashed)
 709                                 dput(unhashed);
 710                             return ERR_PTR(-ERESTARTNOINTR);
 711                         }
 712                 }
 713                 if (!oz_mode) {
 714                         spin_lock(&dentry->d_lock);
 715                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 716                         spin_unlock(&dentry->d_lock);
 717                 }
 718         }
 719
 720         /*
 721          * If this dentry is unhashed, then we shouldn't honour this
 722          * lookup.  Returning ENOENT here doesn't do the right thing
 723          * for all system calls, but it should be OK for the operations
 724          * we permit from an autofs.
 725          */
 726         if (!oz_mode && d_unhashed(dentry)) {
 727                 /*
 728                  * A user space application can (and has done in the past)
 729                  * remove and re-create this directory during the callback.
 730                  * This can leave us with an unhashed dentry, but a
 731                  * successful mount!  So we need to perform another
 732                  * cached lookup in case the dentry now exists.
 733                  */
 734                 struct dentry *parent = dentry->d_parent;
 735                 struct dentry *new = d_lookup(parent, &dentry->d_name);
 736                 if (new != NULL)
 737                         dentry = new;
 738                 else
 739                         dentry = ERR_PTR(-ENOENT);
 740
 741                 if (unhashed)
 742                         dput(unhashed);
 743
 744                 return dentry;
 745         }
 746
 747         if (unhashed)
 748                 return unhashed;
 749
 750         return NULL;
 751 }
 752
 753 static int autofs4_dir_symlink(struct inode *dir,
 754                                struct dentry *dentry,
 755                                const char *symname)
 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         struct inode *inode;
 761         char *cp;
 762
 763         DPRINTK("%s <- %.*s", symname,
 764                 dentry->d_name.len, dentry->d_name.name);
 765
 766         if (!autofs4_oz_mode(sbi))
 767                 return -EACCES;
 768
 769         ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
 770         if (!ino)
 771                 return -ENOMEM;
 772
 773         spin_lock(&sbi->lookup_lock);
 774         if (!list_empty(&ino->active))
 775                 list_del_init(&ino->active);
 776         spin_unlock(&sbi->lookup_lock);
 777
 778         cp = kmalloc(ino->size + 1, GFP_KERNEL);
 779         if (!cp) {
 780                 if (!dentry->d_fsdata)
 781                         kfree(ino);
 782                 return -ENOMEM;
 783         }
 784
 785         strcpy(cp, symname);
 786
 787         inode = autofs4_get_inode(dir->i_sb, ino);
 788         if (!inode) {
 789                 kfree(cp);
 790                 if (!dentry->d_fsdata)
 791                         kfree(ino);
 792                 return -ENOMEM;
 793         }
 794         d_add(dentry, inode);
 795
 796         if (dir == dir->i_sb->s_root->d_inode)
 797                 dentry->d_op = &autofs4_root_dentry_operations;
 798         else
 799                 dentry->d_op = &autofs4_dentry_operations;
 800
 801         dentry->d_fsdata = ino;
 802         ino->dentry = dget(dentry);
 803         atomic_inc(&ino->count);
 804         p_ino = autofs4_dentry_ino(dentry->d_parent);
 805         if (p_ino && dentry->d_parent != dentry)
 806                 atomic_inc(&p_ino->count);
 807         ino->inode = inode;
 808
 809         ino->size = strlen(symname);
 810         ino->u.symlink = cp;
 811         dir->i_mtime = CURRENT_TIME;
 812
 813         return 0;
 814 }
 815
 816 /*
 817  * NOTE!
 818  *
 819  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 820  * that the file no longer exists. However, doing that means that the
 821  * VFS layer can turn the dentry into a negative dentry.  We don't want
 822  * this, because the unlink is probably the result of an expire.
 823  * We simply d_drop it and add it to a expiring list in the super block,
 824  * which allows the dentry lookup to check for an incomplete expire.
 825  *
 826  * If a process is blocked on the dentry waiting for the expire to finish,
 827  * it will invalidate the dentry and try to mount with a new one.
 828  *
 829  * Also see autofs4_dir_rmdir()..
 830  */
 831 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
 832 {
 833         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 834         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 835         struct autofs_info *p_ino;
 836
 837         /* This allows root to remove symlinks */
 838         if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
 839                 return -EACCES;
 840
 841         if (atomic_dec_and_test(&ino->count)) {
 842                 p_ino = autofs4_dentry_ino(dentry->d_parent);
 843                 if (p_ino && dentry->d_parent != dentry)
 844                         atomic_dec(&p_ino->count);
 845         }
 846         dput(ino->dentry);
 847
 848         dentry->d_inode->i_size = 0;
 849         clear_nlink(dentry->d_inode);
 850
 851         dir->i_mtime = CURRENT_TIME;
 852
 853         spin_lock(&dcache_lock);
 854         spin_lock(&sbi->lookup_lock);
 855         if (list_empty(&ino->expiring))
 856                 list_add(&ino->expiring, &sbi->expiring_list);
 857         spin_unlock(&sbi->lookup_lock);
 858         spin_lock(&dentry->d_lock);
 859         __d_drop(dentry);
 860         spin_unlock(&dentry->d_lock);
 861         spin_unlock(&dcache_lock);
 862
 863         return 0;
 864 }
 865
 866 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
 867 {
 868         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 869         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 870         struct autofs_info *p_ino;
 871
 872         DPRINTK("dentry %p, removing %.*s",
 873                 dentry, dentry->d_name.len, dentry->d_name.name);
 874
 875         if (!autofs4_oz_mode(sbi))
 876                 return -EACCES;
 877
 878         spin_lock(&dcache_lock);
 879         if (!list_empty(&dentry->d_subdirs)) {
 880                 spin_unlock(&dcache_lock);
 881                 return -ENOTEMPTY;
 882         }
 883         spin_lock(&sbi->lookup_lock);
 884         if (list_empty(&ino->expiring))
 885                 list_add(&ino->expiring, &sbi->expiring_list);
 886         spin_unlock(&sbi->lookup_lock);
 887         spin_lock(&dentry->d_lock);
 888         __d_drop(dentry);
 889         spin_unlock(&dentry->d_lock);
 890         spin_unlock(&dcache_lock);
 891
 892         if (atomic_dec_and_test(&ino->count)) {
 893                 p_ino = autofs4_dentry_ino(dentry->d_parent);
 894                 if (p_ino && dentry->d_parent != dentry)
 895                         atomic_dec(&p_ino->count);
 896         }
 897         dput(ino->dentry);
 898         dentry->d_inode->i_size = 0;
 899         clear_nlink(dentry->d_inode);
 900
 901         if (dir->i_nlink)
 902                 drop_nlink(dir);
 903
 904         return 0;
 905 }
 906
 907 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 908 {
 909         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 910         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 911         struct autofs_info *p_ino;
 912         struct inode *inode;
 913
 914         if (!autofs4_oz_mode(sbi))
 915                 return -EACCES;
 916
 917         DPRINTK("dentry %p, creating %.*s",
 918                 dentry, dentry->d_name.len, dentry->d_name.name);
 919
 920         ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
 921         if (!ino)
 922                 return -ENOMEM;
 923
 924         spin_lock(&sbi->lookup_lock);
 925         if (!list_empty(&ino->active))
 926                 list_del_init(&ino->active);
 927         spin_unlock(&sbi->lookup_lock);
 928
 929         inode = autofs4_get_inode(dir->i_sb, ino);
 930         if (!inode) {
 931                 if (!dentry->d_fsdata)
 932                         kfree(ino);
 933                 return -ENOMEM;
 934         }
 935         d_add(dentry, inode);
 936
 937         if (dir == dir->i_sb->s_root->d_inode)
 938                 dentry->d_op = &autofs4_root_dentry_operations;
 939         else
 940                 dentry->d_op = &autofs4_dentry_operations;
 941
 942         dentry->d_fsdata = ino;
 943         ino->dentry = dget(dentry);
 944         atomic_inc(&ino->count);
 945         p_ino = autofs4_dentry_ino(dentry->d_parent);
 946         if (p_ino && dentry->d_parent != dentry)
 947                 atomic_inc(&p_ino->count);
 948         ino->inode = inode;
 949         inc_nlink(dir);
 950         dir->i_mtime = CURRENT_TIME;
 951
 952         return 0;
 953 }
 954
 955 /* Get/set timeout ioctl() operation */
 956 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
 957                                          unsigned long __user *p)
 958 {
 959         int rv;
 960         unsigned long ntimeout;
 961
 962         if ((rv = get_user(ntimeout, p)) ||
 963              (rv = put_user(sbi->exp_timeout/HZ, p)))
 964                 return rv;
 965
 966         if (ntimeout > ULONG_MAX/HZ)
 967                 sbi->exp_timeout = 0;
 968         else
 969                 sbi->exp_timeout = ntimeout * HZ;
 970
 971         return 0;
 972 }
 973
 974 /* Return protocol version */
 975 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
 976 {
 977         return put_user(sbi->version, p);
 978 }
 979
 980 /* Return protocol sub version */
 981 static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
 982 {
 983         return put_user(sbi->sub_version, p);
 984 }
 985
 986 /*
 987  * Tells the daemon whether we need to reghost or not. Also, clears
 988  * the reghost_needed flag.
 989  */
 990 static inline int autofs4_ask_reghost(struct autofs_sb_info *sbi, int __user *p)
 991 {
 992         int status;
 993
 994         DPRINTK("returning %d", sbi->needs_reghost);
 995
 996         status = put_user(sbi->needs_reghost, p);
 997         if (status)
 998                 return status;
 999
1000         sbi->needs_reghost = 0;
1001         return 0;
1002 }
1003
1004 /*
1005  * Enable / Disable reghosting ioctl() operation
1006  */
1007 static inline int autofs4_toggle_reghost(struct autofs_sb_info *sbi, int __user *p)
1008 {
1009         int status;
1010         int val;
1011
1012         status = get_user(val, p);
1013
1014         DPRINTK("reghost = %d", val);
1015
1016         if (status)
1017                 return status;
1018
1019         /* turn on/off reghosting, with the val */
1020         sbi->reghost_enabled = val;
1021         return 0;
1022 }
1023
1024 /*
1025 * Tells the daemon whether it can umount the autofs mount.
1026 */
1027 static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
1028 {
1029         int status = 0;
1030
1031         if (may_umount(mnt))
1032                 status = 1;
1033
1034         DPRINTK("returning %d", status);
1035
1036         status = put_user(status, p);
1037
1038         return status;
1039 }
1040
1041 /* Identify autofs4_dentries - this is so we can tell if there's
1042    an extra dentry refcount or not.  We only hold a refcount on the
1043    dentry if its non-negative (ie, d_inode != NULL)
1044 */
1045 int is_autofs4_dentry(struct dentry *dentry)
1046 {
1047         return dentry && dentry->d_inode &&
1048                 (dentry->d_op == &autofs4_root_dentry_operations ||
1049                  dentry->d_op == &autofs4_dentry_operations) &&
1050                 dentry->d_fsdata != NULL;
1051 }
1052
1053 /*
1054  * ioctl()'s on the root directory is the chief method for the daemon to
1055  * generate kernel reactions
1056  */
1057 static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
1058                              unsigned int cmd, unsigned long arg)
1059 {
1060         struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
1061         void __user *p = (void __user *)arg;
1062
1063         DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
1064                 cmd,arg,sbi,task_pgrp_nr(current));
1065
1066         if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
1067              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
1068                 return -ENOTTY;
1069
1070         if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
1071                 return -EPERM;
1072
1073         switch(cmd) {
1074         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
1075                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
1076         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
1077                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
1078         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
1079                 autofs4_catatonic_mode(sbi);
1080                 return 0;
1081         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
1082                 return autofs4_get_protover(sbi, p);
1083         case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
1084                 return autofs4_get_protosubver(sbi, p);
1085         case AUTOFS_IOC_SETTIMEOUT:
1086                 return autofs4_get_set_timeout(sbi, p);
1087
1088         case AUTOFS_IOC_TOGGLEREGHOST:
1089                 return autofs4_toggle_reghost(sbi, p);
1090         case AUTOFS_IOC_ASKREGHOST:
1091                 return autofs4_ask_reghost(sbi, p);
1092
1093         case AUTOFS_IOC_ASKUMOUNT:
1094                 return autofs4_ask_umount(filp->f_path.mnt, p);
1095
1096         /* return a single thing to expire */
1097         case AUTOFS_IOC_EXPIRE:
1098                 return autofs4_expire_run(inode->i_sb,filp->f_path.mnt,sbi, p);
1099         /* same as above, but can send multiple expires through pipe */
1100         case AUTOFS_IOC_EXPIRE_MULTI:
1101                 return autofs4_expire_multi(inode->i_sb,filp->f_path.mnt,sbi, p);
1102
1103         default:
1104                 return -ENOSYS;
1105         }
1106 }