linux/fs/autofs4/root.c
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   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/slab.h>
  19#include <linux/param.h>
  20#include <linux/time.h>
  21#include <linux/compat.h>
  22#include <linux/mutex.h>
  23
  24#include "autofs_i.h"
  25
  26static int autofs4_dir_symlink(struct inode *,struct dentry *,const char *);
  27static int autofs4_dir_unlink(struct inode *,struct dentry *);
  28static int autofs4_dir_rmdir(struct inode *,struct dentry *);
  29static int autofs4_dir_mkdir(struct inode *,struct dentry *,umode_t);
  30static long autofs4_root_ioctl(struct file *,unsigned int,unsigned long);
  31#ifdef CONFIG_COMPAT
  32static long autofs4_root_compat_ioctl(struct file *,unsigned int,unsigned long);
  33#endif
  34static int autofs4_dir_open(struct inode *inode, struct file *file);
  35static struct dentry *autofs4_lookup(struct inode *,struct dentry *, unsigned int);
  36static struct vfsmount *autofs4_d_automount(struct path *);
  37static int autofs4_d_manage(struct dentry *, bool);
  38static void autofs4_dentry_release(struct dentry *);
  39
  40const struct file_operations autofs4_root_operations = {
  41        .open           = dcache_dir_open,
  42        .release        = dcache_dir_close,
  43        .read           = generic_read_dir,
  44        .readdir        = dcache_readdir,
  45        .llseek         = dcache_dir_lseek,
  46        .unlocked_ioctl = autofs4_root_ioctl,
  47#ifdef CONFIG_COMPAT
  48        .compat_ioctl   = autofs4_root_compat_ioctl,
  49#endif
  50};
  51
  52const struct file_operations autofs4_dir_operations = {
  53        .open           = autofs4_dir_open,
  54        .release        = dcache_dir_close,
  55        .read           = generic_read_dir,
  56        .readdir        = dcache_readdir,
  57        .llseek         = dcache_dir_lseek,
  58};
  59
  60const struct inode_operations autofs4_dir_inode_operations = {
  61        .lookup         = autofs4_lookup,
  62        .unlink         = autofs4_dir_unlink,
  63        .symlink        = autofs4_dir_symlink,
  64        .mkdir          = autofs4_dir_mkdir,
  65        .rmdir          = autofs4_dir_rmdir,
  66};
  67
  68const struct dentry_operations autofs4_dentry_operations = {
  69        .d_automount    = autofs4_d_automount,
  70        .d_manage       = autofs4_d_manage,
  71        .d_release      = autofs4_dentry_release,
  72};
  73
  74static void autofs4_add_active(struct dentry *dentry)
  75{
  76        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
  77        struct autofs_info *ino = autofs4_dentry_ino(dentry);
  78        if (ino) {
  79                spin_lock(&sbi->lookup_lock);
  80                if (!ino->active_count) {
  81                        if (list_empty(&ino->active))
  82                                list_add(&ino->active, &sbi->active_list);
  83                }
  84                ino->active_count++;
  85                spin_unlock(&sbi->lookup_lock);
  86        }
  87        return;
  88}
  89
  90static void autofs4_del_active(struct dentry *dentry)
  91{
  92        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
  93        struct autofs_info *ino = autofs4_dentry_ino(dentry);
  94        if (ino) {
  95                spin_lock(&sbi->lookup_lock);
  96                ino->active_count--;
  97                if (!ino->active_count) {
  98                        if (!list_empty(&ino->active))
  99                                list_del_init(&ino->active);
 100                }
 101                spin_unlock(&sbi->lookup_lock);
 102        }
 103        return;
 104}
 105
 106static int autofs4_dir_open(struct inode *inode, struct file *file)
 107{
 108        struct dentry *dentry = file->f_path.dentry;
 109        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 110
 111        DPRINTK("file=%p dentry=%p %.*s",
 112                file, dentry, dentry->d_name.len, dentry->d_name.name);
 113
 114        if (autofs4_oz_mode(sbi))
 115                goto out;
 116
 117        /*
 118         * An empty directory in an autofs file system is always a
 119         * mount point. The daemon must have failed to mount this
 120         * during lookup so it doesn't exist. This can happen, for
 121         * example, if user space returns an incorrect status for a
 122         * mount request. Otherwise we're doing a readdir on the
 123         * autofs file system so just let the libfs routines handle
 124         * it.
 125         */
 126        spin_lock(&sbi->lookup_lock);
 127        if (!d_mountpoint(dentry) && simple_empty(dentry)) {
 128                spin_unlock(&sbi->lookup_lock);
 129                return -ENOENT;
 130        }
 131        spin_unlock(&sbi->lookup_lock);
 132
 133out:
 134        return dcache_dir_open(inode, file);
 135}
 136
 137static void autofs4_dentry_release(struct dentry *de)
 138{
 139        struct autofs_info *ino = autofs4_dentry_ino(de);
 140        struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb);
 141
 142        DPRINTK("releasing %p", de);
 143
 144        if (!ino)
 145                return;
 146
 147        if (sbi) {
 148                spin_lock(&sbi->lookup_lock);
 149                if (!list_empty(&ino->active))
 150                        list_del(&ino->active);
 151                if (!list_empty(&ino->expiring))
 152                        list_del(&ino->expiring);
 153                spin_unlock(&sbi->lookup_lock);
 154        }
 155
 156        autofs4_free_ino(ino);
 157}
 158
 159static struct dentry *autofs4_lookup_active(struct dentry *dentry)
 160{
 161        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 162        struct dentry *parent = dentry->d_parent;
 163        struct qstr *name = &dentry->d_name;
 164        unsigned int len = name->len;
 165        unsigned int hash = name->hash;
 166        const unsigned char *str = name->name;
 167        struct list_head *p, *head;
 168
 169        spin_lock(&sbi->lookup_lock);
 170        head = &sbi->active_list;
 171        list_for_each(p, head) {
 172                struct autofs_info *ino;
 173                struct dentry *active;
 174                struct qstr *qstr;
 175
 176                ino = list_entry(p, struct autofs_info, active);
 177                active = ino->dentry;
 178
 179                spin_lock(&active->d_lock);
 180
 181                /* Already gone? */
 182                if (active->d_count == 0)
 183                        goto next;
 184
 185                qstr = &active->d_name;
 186
 187                if (active->d_name.hash != hash)
 188                        goto next;
 189                if (active->d_parent != parent)
 190                        goto next;
 191
 192                if (qstr->len != len)
 193                        goto next;
 194                if (memcmp(qstr->name, str, len))
 195                        goto next;
 196
 197                if (d_unhashed(active)) {
 198                        dget_dlock(active);
 199                        spin_unlock(&active->d_lock);
 200                        spin_unlock(&sbi->lookup_lock);
 201                        return active;
 202                }
 203next:
 204                spin_unlock(&active->d_lock);
 205        }
 206        spin_unlock(&sbi->lookup_lock);
 207
 208        return NULL;
 209}
 210
 211static struct dentry *autofs4_lookup_expiring(struct dentry *dentry)
 212{
 213        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 214        struct dentry *parent = dentry->d_parent;
 215        struct qstr *name = &dentry->d_name;
 216        unsigned int len = name->len;
 217        unsigned int hash = name->hash;
 218        const unsigned char *str = name->name;
 219        struct list_head *p, *head;
 220
 221        spin_lock(&sbi->lookup_lock);
 222        head = &sbi->expiring_list;
 223        list_for_each(p, head) {
 224                struct autofs_info *ino;
 225                struct dentry *expiring;
 226                struct qstr *qstr;
 227
 228                ino = list_entry(p, struct autofs_info, expiring);
 229                expiring = ino->dentry;
 230
 231                spin_lock(&expiring->d_lock);
 232
 233                /* Bad luck, we've already been dentry_iput */
 234                if (!expiring->d_inode)
 235                        goto next;
 236
 237                qstr = &expiring->d_name;
 238
 239                if (expiring->d_name.hash != hash)
 240                        goto next;
 241                if (expiring->d_parent != parent)
 242                        goto next;
 243
 244                if (qstr->len != len)
 245                        goto next;
 246                if (memcmp(qstr->name, str, len))
 247                        goto next;
 248
 249                if (d_unhashed(expiring)) {
 250                        dget_dlock(expiring);
 251                        spin_unlock(&expiring->d_lock);
 252                        spin_unlock(&sbi->lookup_lock);
 253                        return expiring;
 254                }
 255next:
 256                spin_unlock(&expiring->d_lock);
 257        }
 258        spin_unlock(&sbi->lookup_lock);
 259
 260        return NULL;
 261}
 262
 263static int autofs4_mount_wait(struct dentry *dentry)
 264{
 265        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 266        struct autofs_info *ino = autofs4_dentry_ino(dentry);
 267        int status = 0;
 268
 269        if (ino->flags & AUTOFS_INF_PENDING) {
 270                DPRINTK("waiting for mount name=%.*s",
 271                        dentry->d_name.len, dentry->d_name.name);
 272                status = autofs4_wait(sbi, dentry, NFY_MOUNT);
 273                DPRINTK("mount wait done status=%d", status);
 274        }
 275        ino->last_used = jiffies;
 276        return status;
 277}
 278
 279static int do_expire_wait(struct dentry *dentry)
 280{
 281        struct dentry *expiring;
 282
 283        expiring = autofs4_lookup_expiring(dentry);
 284        if (!expiring)
 285                return autofs4_expire_wait(dentry);
 286        else {
 287                /*
 288                 * If we are racing with expire the request might not
 289                 * be quite complete, but the directory has been removed
 290                 * so it must have been successful, just wait for it.
 291                 */
 292                autofs4_expire_wait(expiring);
 293                autofs4_del_expiring(expiring);
 294                dput(expiring);
 295        }
 296        return 0;
 297}
 298
 299static struct dentry *autofs4_mountpoint_changed(struct path *path)
 300{
 301        struct dentry *dentry = path->dentry;
 302        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 303
 304        /*
 305         * If this is an indirect mount the dentry could have gone away
 306         * as a result of an expire and a new one created.
 307         */
 308        if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) {
 309                struct dentry *parent = dentry->d_parent;
 310                struct autofs_info *ino;
 311                struct dentry *new = d_lookup(parent, &dentry->d_name);
 312                if (!new)
 313                        return NULL;
 314                ino = autofs4_dentry_ino(new);
 315                ino->last_used = jiffies;
 316                dput(path->dentry);
 317                path->dentry = new;
 318        }
 319        return path->dentry;
 320}
 321
 322static struct vfsmount *autofs4_d_automount(struct path *path)
 323{
 324        struct dentry *dentry = path->dentry;
 325        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 326        struct autofs_info *ino = autofs4_dentry_ino(dentry);
 327        int status;
 328
 329        DPRINTK("dentry=%p %.*s",
 330                dentry, dentry->d_name.len, dentry->d_name.name);
 331
 332        /* The daemon never triggers a mount. */
 333        if (autofs4_oz_mode(sbi))
 334                return NULL;
 335
 336        /*
 337         * If an expire request is pending everyone must wait.
 338         * If the expire fails we're still mounted so continue
 339         * the follow and return. A return of -EAGAIN (which only
 340         * happens with indirect mounts) means the expire completed
 341         * and the directory was removed, so just go ahead and try
 342         * the mount.
 343         */
 344        status = do_expire_wait(dentry);
 345        if (status && status != -EAGAIN)
 346                return NULL;
 347
 348        /* Callback to the daemon to perform the mount or wait */
 349        spin_lock(&sbi->fs_lock);
 350        if (ino->flags & AUTOFS_INF_PENDING) {
 351                spin_unlock(&sbi->fs_lock);
 352                status = autofs4_mount_wait(dentry);
 353                if (status)
 354                        return ERR_PTR(status);
 355                goto done;
 356        }
 357
 358        /*
 359         * If the dentry is a symlink it's equivalent to a directory
 360         * having d_mountpoint() true, so there's no need to call back
 361         * to the daemon.
 362         */
 363        if (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode)) {
 364                spin_unlock(&sbi->fs_lock);
 365                goto done;
 366        }
 367
 368        if (!d_mountpoint(dentry)) {
 369                /*
 370                 * It's possible that user space hasn't removed directories
 371                 * after umounting a rootless multi-mount, although it
 372                 * should. For v5 have_submounts() is sufficient to handle
 373                 * this because the leaves of the directory tree under the
 374                 * mount never trigger mounts themselves (they have an autofs
 375                 * trigger mount mounted on them). But v4 pseudo direct mounts
 376                 * do need the leaves to to trigger mounts. In this case we
 377                 * have no choice but to use the list_empty() check and
 378                 * require user space behave.
 379                 */
 380                if (sbi->version > 4) {
 381                        if (have_submounts(dentry)) {
 382                                spin_unlock(&sbi->fs_lock);
 383                                goto done;
 384                        }
 385                } else {
 386                        if (!simple_empty(dentry))
 387                                goto done;
 388                }
 389                ino->flags |= AUTOFS_INF_PENDING;
 390                spin_unlock(&sbi->fs_lock);
 391                status = autofs4_mount_wait(dentry);
 392                spin_lock(&sbi->fs_lock);
 393                ino->flags &= ~AUTOFS_INF_PENDING;
 394                if (status) {
 395                        spin_unlock(&sbi->fs_lock);
 396                        return ERR_PTR(status);
 397                }
 398        }
 399        spin_unlock(&sbi->fs_lock);
 400done:
 401        /* Mount succeeded, check if we ended up with a new dentry */
 402        dentry = autofs4_mountpoint_changed(path);
 403        if (!dentry)
 404                return ERR_PTR(-ENOENT);
 405
 406        return NULL;
 407}
 408
 409int autofs4_d_manage(struct dentry *dentry, bool rcu_walk)
 410{
 411        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 412        struct autofs_info *ino = autofs4_dentry_ino(dentry);
 413        int status;
 414
 415        DPRINTK("dentry=%p %.*s",
 416                dentry, dentry->d_name.len, dentry->d_name.name);
 417
 418        /* The daemon never waits. */
 419        if (autofs4_oz_mode(sbi)) {
 420                if (rcu_walk)
 421                        return 0;
 422                if (!d_mountpoint(dentry))
 423                        return -EISDIR;
 424                return 0;
 425        }
 426
 427        /* We need to sleep, so we need pathwalk to be in ref-mode */
 428        if (rcu_walk)
 429                return -ECHILD;
 430
 431        /* Wait for pending expires */
 432        do_expire_wait(dentry);
 433
 434        /*
 435         * This dentry may be under construction so wait on mount
 436         * completion.
 437         */
 438        status = autofs4_mount_wait(dentry);
 439        if (status)
 440                return status;
 441
 442        spin_lock(&sbi->fs_lock);
 443        /*
 444         * If the dentry has been selected for expire while we slept
 445         * on the lock then it might go away. We'll deal with that in
 446         * ->d_automount() and wait on a new mount if the expire
 447         * succeeds or return here if it doesn't (since there's no
 448         * mount to follow with a rootless multi-mount).
 449         */
 450        if (!(ino->flags & AUTOFS_INF_EXPIRING)) {
 451                /*
 452                 * Any needed mounting has been completed and the path
 453                 * updated so check if this is a rootless multi-mount so
 454                 * we can avoid needless calls ->d_automount() and avoid
 455                 * an incorrect ELOOP error return.
 456                 */
 457                if ((!d_mountpoint(dentry) && !simple_empty(dentry)) ||
 458                    (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode)))
 459                        status = -EISDIR;
 460        }
 461        spin_unlock(&sbi->fs_lock);
 462
 463        return status;
 464}
 465
 466/* Lookups in the root directory */
 467static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
 468{
 469        struct autofs_sb_info *sbi;
 470        struct autofs_info *ino;
 471        struct dentry *active;
 472
 473        DPRINTK("name = %.*s", dentry->d_name.len, dentry->d_name.name);
 474
 475        /* File name too long to exist */
 476        if (dentry->d_name.len > NAME_MAX)
 477                return ERR_PTR(-ENAMETOOLONG);
 478
 479        sbi = autofs4_sbi(dir->i_sb);
 480
 481        DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
 482                current->pid, task_pgrp_nr(current), sbi->catatonic,
 483                autofs4_oz_mode(sbi));
 484
 485        active = autofs4_lookup_active(dentry);
 486        if (active) {
 487                return active;
 488        } else {
 489                /*
 490                 * A dentry that is not within the root can never trigger a
 491                 * mount operation, unless the directory already exists, so we
 492                 * can return fail immediately.  The daemon however does need
 493                 * to create directories within the file system.
 494                 */
 495                if (!autofs4_oz_mode(sbi) && !IS_ROOT(dentry->d_parent))
 496                        return ERR_PTR(-ENOENT);
 497
 498                /* Mark entries in the root as mount triggers */
 499                if (autofs_type_indirect(sbi->type) && IS_ROOT(dentry->d_parent))
 500                        __managed_dentry_set_managed(dentry);
 501
 502                ino = autofs4_new_ino(sbi);
 503                if (!ino)
 504                        return ERR_PTR(-ENOMEM);
 505
 506                dentry->d_fsdata = ino;
 507                ino->dentry = dentry;
 508
 509                autofs4_add_active(dentry);
 510
 511                d_instantiate(dentry, NULL);
 512        }
 513        return NULL;
 514}
 515
 516static int autofs4_dir_symlink(struct inode *dir, 
 517                               struct dentry *dentry,
 518                               const char *symname)
 519{
 520        struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 521        struct autofs_info *ino = autofs4_dentry_ino(dentry);
 522        struct autofs_info *p_ino;
 523        struct inode *inode;
 524        size_t size = strlen(symname);
 525        char *cp;
 526
 527        DPRINTK("%s <- %.*s", symname,
 528                dentry->d_name.len, dentry->d_name.name);
 529
 530        if (!autofs4_oz_mode(sbi))
 531                return -EACCES;
 532
 533        BUG_ON(!ino);
 534
 535        autofs4_clean_ino(ino);
 536
 537        autofs4_del_active(dentry);
 538
 539        cp = kmalloc(size + 1, GFP_KERNEL);
 540        if (!cp)
 541                return -ENOMEM;
 542
 543        strcpy(cp, symname);
 544
 545        inode = autofs4_get_inode(dir->i_sb, S_IFLNK | 0555);
 546        if (!inode) {
 547                kfree(cp);
 548                if (!dentry->d_fsdata)
 549                        kfree(ino);
 550                return -ENOMEM;
 551        }
 552        inode->i_private = cp;
 553        inode->i_size = size;
 554        d_add(dentry, inode);
 555
 556        dget(dentry);
 557        atomic_inc(&ino->count);
 558        p_ino = autofs4_dentry_ino(dentry->d_parent);
 559        if (p_ino && dentry->d_parent != dentry)
 560                atomic_inc(&p_ino->count);
 561
 562        dir->i_mtime = CURRENT_TIME;
 563
 564        return 0;
 565}
 566
 567/*
 568 * NOTE!
 569 *
 570 * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 571 * that the file no longer exists. However, doing that means that the
 572 * VFS layer can turn the dentry into a negative dentry.  We don't want
 573 * this, because the unlink is probably the result of an expire.
 574 * We simply d_drop it and add it to a expiring list in the super block,
 575 * which allows the dentry lookup to check for an incomplete expire.
 576 *
 577 * If a process is blocked on the dentry waiting for the expire to finish,
 578 * it will invalidate the dentry and try to mount with a new one.
 579 *
 580 * Also see autofs4_dir_rmdir()..
 581 */
 582static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
 583{
 584        struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 585        struct autofs_info *ino = autofs4_dentry_ino(dentry);
 586        struct autofs_info *p_ino;
 587        
 588        /* This allows root to remove symlinks */
 589        if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
 590                return -EACCES;
 591
 592        if (atomic_dec_and_test(&ino->count)) {
 593                p_ino = autofs4_dentry_ino(dentry->d_parent);
 594                if (p_ino && dentry->d_parent != dentry)
 595                        atomic_dec(&p_ino->count);
 596        }
 597        dput(ino->dentry);
 598
 599        dentry->d_inode->i_size = 0;
 600        clear_nlink(dentry->d_inode);
 601
 602        dir->i_mtime = CURRENT_TIME;
 603
 604        spin_lock(&sbi->lookup_lock);
 605        __autofs4_add_expiring(dentry);
 606        d_drop(dentry);
 607        spin_unlock(&sbi->lookup_lock);
 608
 609        return 0;
 610}
 611
 612/*
 613 * Version 4 of autofs provides a pseudo direct mount implementation
 614 * that relies on directories at the leaves of a directory tree under
 615 * an indirect mount to trigger mounts. To allow for this we need to
 616 * set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves
 617 * of the directory tree. There is no need to clear the automount flag
 618 * following a mount or restore it after an expire because these mounts
 619 * are always covered. However, it is necessary to ensure that these
 620 * flags are clear on non-empty directories to avoid unnecessary calls
 621 * during path walks.
 622 */
 623static void autofs_set_leaf_automount_flags(struct dentry *dentry)
 624{
 625        struct dentry *parent;
 626
 627        /* root and dentrys in the root are already handled */
 628        if (IS_ROOT(dentry->d_parent))
 629                return;
 630
 631        managed_dentry_set_managed(dentry);
 632
 633        parent = dentry->d_parent;
 634        /* only consider parents below dentrys in the root */
 635        if (IS_ROOT(parent->d_parent))
 636                return;
 637        managed_dentry_clear_managed(parent);
 638        return;
 639}
 640
 641static void autofs_clear_leaf_automount_flags(struct dentry *dentry)
 642{
 643        struct list_head *d_child;
 644        struct dentry *parent;
 645
 646        /* flags for dentrys in the root are handled elsewhere */
 647        if (IS_ROOT(dentry->d_parent))
 648                return;
 649
 650        managed_dentry_clear_managed(dentry);
 651
 652        parent = dentry->d_parent;
 653        /* only consider parents below dentrys in the root */
 654        if (IS_ROOT(parent->d_parent))
 655                return;
 656        d_child = &dentry->d_u.d_child;
 657        /* Set parent managed if it's becoming empty */
 658        if (d_child->next == &parent->d_subdirs &&
 659            d_child->prev == &parent->d_subdirs)
 660                managed_dentry_set_managed(parent);
 661        return;
 662}
 663
 664static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
 665{
 666        struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 667        struct autofs_info *ino = autofs4_dentry_ino(dentry);
 668        struct autofs_info *p_ino;
 669        
 670        DPRINTK("dentry %p, removing %.*s",
 671                dentry, dentry->d_name.len, dentry->d_name.name);
 672
 673        if (!autofs4_oz_mode(sbi))
 674                return -EACCES;
 675
 676        spin_lock(&sbi->lookup_lock);
 677        if (!simple_empty(dentry)) {
 678                spin_unlock(&sbi->lookup_lock);
 679                return -ENOTEMPTY;
 680        }
 681        __autofs4_add_expiring(dentry);
 682        d_drop(dentry);
 683        spin_unlock(&sbi->lookup_lock);
 684
 685        if (sbi->version < 5)
 686                autofs_clear_leaf_automount_flags(dentry);
 687
 688        if (atomic_dec_and_test(&ino->count)) {
 689                p_ino = autofs4_dentry_ino(dentry->d_parent);
 690                if (p_ino && dentry->d_parent != dentry)
 691                        atomic_dec(&p_ino->count);
 692        }
 693        dput(ino->dentry);
 694        dentry->d_inode->i_size = 0;
 695        clear_nlink(dentry->d_inode);
 696
 697        if (dir->i_nlink)
 698                drop_nlink(dir);
 699
 700        return 0;
 701}
 702
 703static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 704{
 705        struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 706        struct autofs_info *ino = autofs4_dentry_ino(dentry);
 707        struct autofs_info *p_ino;
 708        struct inode *inode;
 709
 710        if (!autofs4_oz_mode(sbi))
 711                return -EACCES;
 712
 713        DPRINTK("dentry %p, creating %.*s",
 714                dentry, dentry->d_name.len, dentry->d_name.name);
 715
 716        BUG_ON(!ino);
 717
 718        autofs4_clean_ino(ino);
 719
 720        autofs4_del_active(dentry);
 721
 722        inode = autofs4_get_inode(dir->i_sb, S_IFDIR | 0555);
 723        if (!inode)
 724                return -ENOMEM;
 725        d_add(dentry, inode);
 726
 727        if (sbi->version < 5)
 728                autofs_set_leaf_automount_flags(dentry);
 729
 730        dget(dentry);
 731        atomic_inc(&ino->count);
 732        p_ino = autofs4_dentry_ino(dentry->d_parent);
 733        if (p_ino && dentry->d_parent != dentry)
 734                atomic_inc(&p_ino->count);
 735        inc_nlink(dir);
 736        dir->i_mtime = CURRENT_TIME;
 737
 738        return 0;
 739}
 740
 741/* Get/set timeout ioctl() operation */
 742#ifdef CONFIG_COMPAT
 743static inline int autofs4_compat_get_set_timeout(struct autofs_sb_info *sbi,
 744                                         compat_ulong_t __user *p)
 745{
 746        int rv;
 747        unsigned long ntimeout;
 748
 749        if ((rv = get_user(ntimeout, p)) ||
 750             (rv = put_user(sbi->exp_timeout/HZ, p)))
 751                return rv;
 752
 753        if (ntimeout > UINT_MAX/HZ)
 754                sbi->exp_timeout = 0;
 755        else
 756                sbi->exp_timeout = ntimeout * HZ;
 757
 758        return 0;
 759}
 760#endif
 761
 762static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
 763                                         unsigned long __user *p)
 764{
 765        int rv;
 766        unsigned long ntimeout;
 767
 768        if ((rv = get_user(ntimeout, p)) ||
 769             (rv = put_user(sbi->exp_timeout/HZ, p)))
 770                return rv;
 771
 772        if (ntimeout > ULONG_MAX/HZ)
 773                sbi->exp_timeout = 0;
 774        else
 775                sbi->exp_timeout = ntimeout * HZ;
 776
 777        return 0;
 778}
 779
 780/* Return protocol version */
 781static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
 782{
 783        return put_user(sbi->version, p);
 784}
 785
 786/* Return protocol sub version */
 787static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
 788{
 789        return put_user(sbi->sub_version, p);
 790}
 791
 792/*
 793* Tells the daemon whether it can umount the autofs mount.
 794*/
 795static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
 796{
 797        int status = 0;
 798
 799        if (may_umount(mnt))
 800                status = 1;
 801
 802        DPRINTK("returning %d", status);
 803
 804        status = put_user(status, p);
 805
 806        return status;
 807}
 808
 809/* Identify autofs4_dentries - this is so we can tell if there's
 810   an extra dentry refcount or not.  We only hold a refcount on the
 811   dentry if its non-negative (ie, d_inode != NULL)
 812*/
 813int is_autofs4_dentry(struct dentry *dentry)
 814{
 815        return dentry && dentry->d_inode &&
 816                dentry->d_op == &autofs4_dentry_operations &&
 817                dentry->d_fsdata != NULL;
 818}
 819
 820/*
 821 * ioctl()'s on the root directory is the chief method for the daemon to
 822 * generate kernel reactions
 823 */
 824static int autofs4_root_ioctl_unlocked(struct inode *inode, struct file *filp,
 825                                       unsigned int cmd, unsigned long arg)
 826{
 827        struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
 828        void __user *p = (void __user *)arg;
 829
 830        DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
 831                cmd,arg,sbi,task_pgrp_nr(current));
 832
 833        if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
 834             _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
 835                return -ENOTTY;
 836        
 837        if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
 838                return -EPERM;
 839        
 840        switch(cmd) {
 841        case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
 842                return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
 843        case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
 844                return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
 845        case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
 846                autofs4_catatonic_mode(sbi);
 847                return 0;
 848        case AUTOFS_IOC_PROTOVER: /* Get protocol version */
 849                return autofs4_get_protover(sbi, p);
 850        case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
 851                return autofs4_get_protosubver(sbi, p);
 852        case AUTOFS_IOC_SETTIMEOUT:
 853                return autofs4_get_set_timeout(sbi, p);
 854#ifdef CONFIG_COMPAT
 855        case AUTOFS_IOC_SETTIMEOUT32:
 856                return autofs4_compat_get_set_timeout(sbi, p);
 857#endif
 858
 859        case AUTOFS_IOC_ASKUMOUNT:
 860                return autofs4_ask_umount(filp->f_path.mnt, p);
 861
 862        /* return a single thing to expire */
 863        case AUTOFS_IOC_EXPIRE:
 864                return autofs4_expire_run(inode->i_sb,filp->f_path.mnt,sbi, p);
 865        /* same as above, but can send multiple expires through pipe */
 866        case AUTOFS_IOC_EXPIRE_MULTI:
 867                return autofs4_expire_multi(inode->i_sb,filp->f_path.mnt,sbi, p);
 868
 869        default:
 870                return -ENOSYS;
 871        }
 872}
 873
 874static long autofs4_root_ioctl(struct file *filp,
 875                               unsigned int cmd, unsigned long arg)
 876{
 877        struct inode *inode = filp->f_dentry->d_inode;
 878        return autofs4_root_ioctl_unlocked(inode, filp, cmd, arg);
 879}
 880
 881#ifdef CONFIG_COMPAT
 882static long autofs4_root_compat_ioctl(struct file *filp,
 883                             unsigned int cmd, unsigned long arg)
 884{
 885        struct inode *inode = filp->f_path.dentry->d_inode;
 886        int ret;
 887
 888        if (cmd == AUTOFS_IOC_READY || cmd == AUTOFS_IOC_FAIL)
 889                ret = autofs4_root_ioctl_unlocked(inode, filp, cmd, arg);
 890        else
 891                ret = autofs4_root_ioctl_unlocked(inode, filp, cmd,
 892                        (unsigned long)compat_ptr(arg));
 893
 894        return ret;
 895}
 896#endif
 897
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