linux/fs/configfs/dir.c
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   1/* -*- mode: c; c-basic-offset: 8; -*-
   2 * vim: noexpandtab sw=8 ts=8 sts=0:
   3 *
   4 * dir.c - Operations for configfs directories.
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public
   8 * License as published by the Free Software Foundation; either
   9 * version 2 of the License, or (at your option) any later version.
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 * General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public
  17 * License along with this program; if not, write to the
  18 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19 * Boston, MA 021110-1307, USA.
  20 *
  21 * Based on sysfs:
  22 *      sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
  23 *
  24 * configfs Copyright (C) 2005 Oracle.  All rights reserved.
  25 */
  26
  27#undef DEBUG
  28
  29#include <linux/fs.h>
  30#include <linux/mount.h>
  31#include <linux/module.h>
  32#include <linux/slab.h>
  33#include <linux/err.h>
  34
  35#include <linux/configfs.h>
  36#include "configfs_internal.h"
  37
  38DECLARE_RWSEM(configfs_rename_sem);
  39/*
  40 * Protects mutations of configfs_dirent linkage together with proper i_mutex
  41 * Also protects mutations of symlinks linkage to target configfs_dirent
  42 * Mutators of configfs_dirent linkage must *both* have the proper inode locked
  43 * and configfs_dirent_lock locked, in that order.
  44 * This allows one to safely traverse configfs_dirent trees and symlinks without
  45 * having to lock inodes.
  46 *
  47 * Protects setting of CONFIGFS_USET_DROPPING: checking the flag
  48 * unlocked is not reliable unless in detach_groups() called from
  49 * rmdir()/unregister() and from configfs_attach_group()
  50 */
  51DEFINE_SPINLOCK(configfs_dirent_lock);
  52
  53static void configfs_d_iput(struct dentry * dentry,
  54                            struct inode * inode)
  55{
  56        struct configfs_dirent *sd = dentry->d_fsdata;
  57
  58        if (sd) {
  59                BUG_ON(sd->s_dentry != dentry);
  60                /* Coordinate with configfs_readdir */
  61                spin_lock(&configfs_dirent_lock);
  62                sd->s_dentry = NULL;
  63                spin_unlock(&configfs_dirent_lock);
  64                configfs_put(sd);
  65        }
  66        iput(inode);
  67}
  68
  69/*
  70 * We _must_ delete our dentries on last dput, as the chain-to-parent
  71 * behavior is required to clear the parents of default_groups.
  72 */
  73static int configfs_d_delete(const struct dentry *dentry)
  74{
  75        return 1;
  76}
  77
  78const struct dentry_operations configfs_dentry_ops = {
  79        .d_iput         = configfs_d_iput,
  80        /* simple_delete_dentry() isn't exported */
  81        .d_delete       = configfs_d_delete,
  82};
  83
  84#ifdef CONFIG_LOCKDEP
  85
  86/*
  87 * Helpers to make lockdep happy with our recursive locking of default groups'
  88 * inodes (see configfs_attach_group() and configfs_detach_group()).
  89 * We put default groups i_mutexes in separate classes according to their depth
  90 * from the youngest non-default group ancestor.
  91 *
  92 * For a non-default group A having default groups A/B, A/C, and A/C/D, default
  93 * groups A/B and A/C will have their inode's mutex in class
  94 * default_group_class[0], and default group A/C/D will be in
  95 * default_group_class[1].
  96 *
  97 * The lock classes are declared and assigned in inode.c, according to the
  98 * s_depth value.
  99 * The s_depth value is initialized to -1, adjusted to >= 0 when attaching
 100 * default groups, and reset to -1 when all default groups are attached. During
 101 * attachment, if configfs_create() sees s_depth > 0, the lock class of the new
 102 * inode's mutex is set to default_group_class[s_depth - 1].
 103 */
 104
 105static void configfs_init_dirent_depth(struct configfs_dirent *sd)
 106{
 107        sd->s_depth = -1;
 108}
 109
 110static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
 111                                          struct configfs_dirent *sd)
 112{
 113        int parent_depth = parent_sd->s_depth;
 114
 115        if (parent_depth >= 0)
 116                sd->s_depth = parent_depth + 1;
 117}
 118
 119static void
 120configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
 121{
 122        /*
 123         * item's i_mutex class is already setup, so s_depth is now only
 124         * used to set new sub-directories s_depth, which is always done
 125         * with item's i_mutex locked.
 126         */
 127        /*
 128         *  sd->s_depth == -1 iff we are a non default group.
 129         *  else (we are a default group) sd->s_depth > 0 (see
 130         *  create_dir()).
 131         */
 132        if (sd->s_depth == -1)
 133                /*
 134                 * We are a non default group and we are going to create
 135                 * default groups.
 136                 */
 137                sd->s_depth = 0;
 138}
 139
 140static void
 141configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
 142{
 143        /* We will not create default groups anymore. */
 144        sd->s_depth = -1;
 145}
 146
 147#else /* CONFIG_LOCKDEP */
 148
 149static void configfs_init_dirent_depth(struct configfs_dirent *sd)
 150{
 151}
 152
 153static void configfs_set_dir_dirent_depth(struct configfs_dirent *parent_sd,
 154                                          struct configfs_dirent *sd)
 155{
 156}
 157
 158static void
 159configfs_adjust_dir_dirent_depth_before_populate(struct configfs_dirent *sd)
 160{
 161}
 162
 163static void
 164configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
 165{
 166}
 167
 168#endif /* CONFIG_LOCKDEP */
 169
 170/*
 171 * Allocates a new configfs_dirent and links it to the parent configfs_dirent
 172 */
 173static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *parent_sd,
 174                                                   void *element, int type)
 175{
 176        struct configfs_dirent * sd;
 177
 178        sd = kmem_cache_zalloc(configfs_dir_cachep, GFP_KERNEL);
 179        if (!sd)
 180                return ERR_PTR(-ENOMEM);
 181
 182        atomic_set(&sd->s_count, 1);
 183        INIT_LIST_HEAD(&sd->s_links);
 184        INIT_LIST_HEAD(&sd->s_children);
 185        sd->s_element = element;
 186        sd->s_type = type;
 187        configfs_init_dirent_depth(sd);
 188        spin_lock(&configfs_dirent_lock);
 189        if (parent_sd->s_type & CONFIGFS_USET_DROPPING) {
 190                spin_unlock(&configfs_dirent_lock);
 191                kmem_cache_free(configfs_dir_cachep, sd);
 192                return ERR_PTR(-ENOENT);
 193        }
 194        list_add(&sd->s_sibling, &parent_sd->s_children);
 195        spin_unlock(&configfs_dirent_lock);
 196
 197        return sd;
 198}
 199
 200/*
 201 *
 202 * Return -EEXIST if there is already a configfs element with the same
 203 * name for the same parent.
 204 *
 205 * called with parent inode's i_mutex held
 206 */
 207static int configfs_dirent_exists(struct configfs_dirent *parent_sd,
 208                                  const unsigned char *new)
 209{
 210        struct configfs_dirent * sd;
 211
 212        list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 213                if (sd->s_element) {
 214                        const unsigned char *existing = configfs_get_name(sd);
 215                        if (strcmp(existing, new))
 216                                continue;
 217                        else
 218                                return -EEXIST;
 219                }
 220        }
 221
 222        return 0;
 223}
 224
 225
 226int configfs_make_dirent(struct configfs_dirent * parent_sd,
 227                         struct dentry * dentry, void * element,
 228                         umode_t mode, int type)
 229{
 230        struct configfs_dirent * sd;
 231
 232        sd = configfs_new_dirent(parent_sd, element, type);
 233        if (IS_ERR(sd))
 234                return PTR_ERR(sd);
 235
 236        sd->s_mode = mode;
 237        sd->s_dentry = dentry;
 238        if (dentry)
 239                dentry->d_fsdata = configfs_get(sd);
 240
 241        return 0;
 242}
 243
 244static int init_dir(struct inode * inode)
 245{
 246        inode->i_op = &configfs_dir_inode_operations;
 247        inode->i_fop = &configfs_dir_operations;
 248
 249        /* directory inodes start off with i_nlink == 2 (for "." entry) */
 250        inc_nlink(inode);
 251        return 0;
 252}
 253
 254static int configfs_init_file(struct inode * inode)
 255{
 256        inode->i_size = PAGE_SIZE;
 257        inode->i_fop = &configfs_file_operations;
 258        return 0;
 259}
 260
 261static int init_symlink(struct inode * inode)
 262{
 263        inode->i_op = &configfs_symlink_inode_operations;
 264        return 0;
 265}
 266
 267static int create_dir(struct config_item *k, struct dentry *d)
 268{
 269        int error;
 270        umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
 271        struct dentry *p = d->d_parent;
 272
 273        BUG_ON(!k);
 274
 275        error = configfs_dirent_exists(p->d_fsdata, d->d_name.name);
 276        if (!error)
 277                error = configfs_make_dirent(p->d_fsdata, d, k, mode,
 278                                             CONFIGFS_DIR | CONFIGFS_USET_CREATING);
 279        if (!error) {
 280                configfs_set_dir_dirent_depth(p->d_fsdata, d->d_fsdata);
 281                error = configfs_create(d, mode, init_dir);
 282                if (!error) {
 283                        inc_nlink(p->d_inode);
 284                } else {
 285                        struct configfs_dirent *sd = d->d_fsdata;
 286                        if (sd) {
 287                                spin_lock(&configfs_dirent_lock);
 288                                list_del_init(&sd->s_sibling);
 289                                spin_unlock(&configfs_dirent_lock);
 290                                configfs_put(sd);
 291                        }
 292                }
 293        }
 294        return error;
 295}
 296
 297
 298/**
 299 *      configfs_create_dir - create a directory for an config_item.
 300 *      @item:          config_itemwe're creating directory for.
 301 *      @dentry:        config_item's dentry.
 302 *
 303 *      Note: user-created entries won't be allowed under this new directory
 304 *      until it is validated by configfs_dir_set_ready()
 305 */
 306
 307static int configfs_create_dir(struct config_item * item, struct dentry *dentry)
 308{
 309        int error = create_dir(item, dentry);
 310        if (!error)
 311                item->ci_dentry = dentry;
 312        return error;
 313}
 314
 315/*
 316 * Allow userspace to create new entries under a new directory created with
 317 * configfs_create_dir(), and under all of its chidlren directories recursively.
 318 * @sd          configfs_dirent of the new directory to validate
 319 *
 320 * Caller must hold configfs_dirent_lock.
 321 */
 322static void configfs_dir_set_ready(struct configfs_dirent *sd)
 323{
 324        struct configfs_dirent *child_sd;
 325
 326        sd->s_type &= ~CONFIGFS_USET_CREATING;
 327        list_for_each_entry(child_sd, &sd->s_children, s_sibling)
 328                if (child_sd->s_type & CONFIGFS_USET_CREATING)
 329                        configfs_dir_set_ready(child_sd);
 330}
 331
 332/*
 333 * Check that a directory does not belong to a directory hierarchy being
 334 * attached and not validated yet.
 335 * @sd          configfs_dirent of the directory to check
 336 *
 337 * @return      non-zero iff the directory was validated
 338 *
 339 * Note: takes configfs_dirent_lock, so the result may change from false to true
 340 * in two consecutive calls, but never from true to false.
 341 */
 342int configfs_dirent_is_ready(struct configfs_dirent *sd)
 343{
 344        int ret;
 345
 346        spin_lock(&configfs_dirent_lock);
 347        ret = !(sd->s_type & CONFIGFS_USET_CREATING);
 348        spin_unlock(&configfs_dirent_lock);
 349
 350        return ret;
 351}
 352
 353int configfs_create_link(struct configfs_symlink *sl,
 354                         struct dentry *parent,
 355                         struct dentry *dentry)
 356{
 357        int err = 0;
 358        umode_t mode = S_IFLNK | S_IRWXUGO;
 359
 360        err = configfs_make_dirent(parent->d_fsdata, dentry, sl, mode,
 361                                   CONFIGFS_ITEM_LINK);
 362        if (!err) {
 363                err = configfs_create(dentry, mode, init_symlink);
 364                if (err) {
 365                        struct configfs_dirent *sd = dentry->d_fsdata;
 366                        if (sd) {
 367                                spin_lock(&configfs_dirent_lock);
 368                                list_del_init(&sd->s_sibling);
 369                                spin_unlock(&configfs_dirent_lock);
 370                                configfs_put(sd);
 371                        }
 372                }
 373        }
 374        return err;
 375}
 376
 377static void remove_dir(struct dentry * d)
 378{
 379        struct dentry * parent = dget(d->d_parent);
 380        struct configfs_dirent * sd;
 381
 382        sd = d->d_fsdata;
 383        spin_lock(&configfs_dirent_lock);
 384        list_del_init(&sd->s_sibling);
 385        spin_unlock(&configfs_dirent_lock);
 386        configfs_put(sd);
 387        if (d->d_inode)
 388                simple_rmdir(parent->d_inode,d);
 389
 390        pr_debug(" o %s removing done (%d)\n",d->d_name.name, d_count(d));
 391
 392        dput(parent);
 393}
 394
 395/**
 396 * configfs_remove_dir - remove an config_item's directory.
 397 * @item:       config_item we're removing.
 398 *
 399 * The only thing special about this is that we remove any files in
 400 * the directory before we remove the directory, and we've inlined
 401 * what used to be configfs_rmdir() below, instead of calling separately.
 402 *
 403 * Caller holds the mutex of the item's inode
 404 */
 405
 406static void configfs_remove_dir(struct config_item * item)
 407{
 408        struct dentry * dentry = dget(item->ci_dentry);
 409
 410        if (!dentry)
 411                return;
 412
 413        remove_dir(dentry);
 414        /**
 415         * Drop reference from dget() on entrance.
 416         */
 417        dput(dentry);
 418}
 419
 420
 421/* attaches attribute's configfs_dirent to the dentry corresponding to the
 422 * attribute file
 423 */
 424static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
 425{
 426        struct configfs_attribute * attr = sd->s_element;
 427        int error;
 428
 429        dentry->d_fsdata = configfs_get(sd);
 430        sd->s_dentry = dentry;
 431        error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG,
 432                                configfs_init_file);
 433        if (error) {
 434                configfs_put(sd);
 435                return error;
 436        }
 437
 438        d_rehash(dentry);
 439
 440        return 0;
 441}
 442
 443static struct dentry * configfs_lookup(struct inode *dir,
 444                                       struct dentry *dentry,
 445                                       unsigned int flags)
 446{
 447        struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
 448        struct configfs_dirent * sd;
 449        int found = 0;
 450        int err;
 451
 452        /*
 453         * Fake invisibility if dir belongs to a group/default groups hierarchy
 454         * being attached
 455         *
 456         * This forbids userspace to read/write attributes of items which may
 457         * not complete their initialization, since the dentries of the
 458         * attributes won't be instantiated.
 459         */
 460        err = -ENOENT;
 461        if (!configfs_dirent_is_ready(parent_sd))
 462                goto out;
 463
 464        list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 465                if (sd->s_type & CONFIGFS_NOT_PINNED) {
 466                        const unsigned char * name = configfs_get_name(sd);
 467
 468                        if (strcmp(name, dentry->d_name.name))
 469                                continue;
 470
 471                        found = 1;
 472                        err = configfs_attach_attr(sd, dentry);
 473                        break;
 474                }
 475        }
 476
 477        if (!found) {
 478                /*
 479                 * If it doesn't exist and it isn't a NOT_PINNED item,
 480                 * it must be negative.
 481                 */
 482                if (dentry->d_name.len > NAME_MAX)
 483                        return ERR_PTR(-ENAMETOOLONG);
 484                d_add(dentry, NULL);
 485                return NULL;
 486        }
 487
 488out:
 489        return ERR_PTR(err);
 490}
 491
 492/*
 493 * Only subdirectories count here.  Files (CONFIGFS_NOT_PINNED) are
 494 * attributes and are removed by rmdir().  We recurse, setting
 495 * CONFIGFS_USET_DROPPING on all children that are candidates for
 496 * default detach.
 497 * If there is an error, the caller will reset the flags via
 498 * configfs_detach_rollback().
 499 */
 500static int configfs_detach_prep(struct dentry *dentry, struct mutex **wait_mutex)
 501{
 502        struct configfs_dirent *parent_sd = dentry->d_fsdata;
 503        struct configfs_dirent *sd;
 504        int ret;
 505
 506        /* Mark that we're trying to drop the group */
 507        parent_sd->s_type |= CONFIGFS_USET_DROPPING;
 508
 509        ret = -EBUSY;
 510        if (!list_empty(&parent_sd->s_links))
 511                goto out;
 512
 513        ret = 0;
 514        list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 515                if (!sd->s_element ||
 516                    (sd->s_type & CONFIGFS_NOT_PINNED))
 517                        continue;
 518                if (sd->s_type & CONFIGFS_USET_DEFAULT) {
 519                        /* Abort if racing with mkdir() */
 520                        if (sd->s_type & CONFIGFS_USET_IN_MKDIR) {
 521                                if (wait_mutex)
 522                                        *wait_mutex = &sd->s_dentry->d_inode->i_mutex;
 523                                return -EAGAIN;
 524                        }
 525
 526                        /*
 527                         * Yup, recursive.  If there's a problem, blame
 528                         * deep nesting of default_groups
 529                         */
 530                        ret = configfs_detach_prep(sd->s_dentry, wait_mutex);
 531                        if (!ret)
 532                                continue;
 533                } else
 534                        ret = -ENOTEMPTY;
 535
 536                break;
 537        }
 538
 539out:
 540        return ret;
 541}
 542
 543/*
 544 * Walk the tree, resetting CONFIGFS_USET_DROPPING wherever it was
 545 * set.
 546 */
 547static void configfs_detach_rollback(struct dentry *dentry)
 548{
 549        struct configfs_dirent *parent_sd = dentry->d_fsdata;
 550        struct configfs_dirent *sd;
 551
 552        parent_sd->s_type &= ~CONFIGFS_USET_DROPPING;
 553
 554        list_for_each_entry(sd, &parent_sd->s_children, s_sibling)
 555                if (sd->s_type & CONFIGFS_USET_DEFAULT)
 556                        configfs_detach_rollback(sd->s_dentry);
 557}
 558
 559static void detach_attrs(struct config_item * item)
 560{
 561        struct dentry * dentry = dget(item->ci_dentry);
 562        struct configfs_dirent * parent_sd;
 563        struct configfs_dirent * sd, * tmp;
 564
 565        if (!dentry)
 566                return;
 567
 568        pr_debug("configfs %s: dropping attrs for  dir\n",
 569                 dentry->d_name.name);
 570
 571        parent_sd = dentry->d_fsdata;
 572        list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
 573                if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
 574                        continue;
 575                spin_lock(&configfs_dirent_lock);
 576                list_del_init(&sd->s_sibling);
 577                spin_unlock(&configfs_dirent_lock);
 578                configfs_drop_dentry(sd, dentry);
 579                configfs_put(sd);
 580        }
 581
 582        /**
 583         * Drop reference from dget() on entrance.
 584         */
 585        dput(dentry);
 586}
 587
 588static int populate_attrs(struct config_item *item)
 589{
 590        struct config_item_type *t = item->ci_type;
 591        struct configfs_attribute *attr;
 592        int error = 0;
 593        int i;
 594
 595        if (!t)
 596                return -EINVAL;
 597        if (t->ct_attrs) {
 598                for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
 599                        if ((error = configfs_create_file(item, attr)))
 600                                break;
 601                }
 602        }
 603
 604        if (error)
 605                detach_attrs(item);
 606
 607        return error;
 608}
 609
 610static int configfs_attach_group(struct config_item *parent_item,
 611                                 struct config_item *item,
 612                                 struct dentry *dentry);
 613static void configfs_detach_group(struct config_item *item);
 614
 615static void detach_groups(struct config_group *group)
 616{
 617        struct dentry * dentry = dget(group->cg_item.ci_dentry);
 618        struct dentry *child;
 619        struct configfs_dirent *parent_sd;
 620        struct configfs_dirent *sd, *tmp;
 621
 622        if (!dentry)
 623                return;
 624
 625        parent_sd = dentry->d_fsdata;
 626        list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
 627                if (!sd->s_element ||
 628                    !(sd->s_type & CONFIGFS_USET_DEFAULT))
 629                        continue;
 630
 631                child = sd->s_dentry;
 632
 633                mutex_lock(&child->d_inode->i_mutex);
 634
 635                configfs_detach_group(sd->s_element);
 636                child->d_inode->i_flags |= S_DEAD;
 637                dont_mount(child);
 638
 639                mutex_unlock(&child->d_inode->i_mutex);
 640
 641                d_delete(child);
 642                dput(child);
 643        }
 644
 645        /**
 646         * Drop reference from dget() on entrance.
 647         */
 648        dput(dentry);
 649}
 650
 651/*
 652 * This fakes mkdir(2) on a default_groups[] entry.  It
 653 * creates a dentry, attachs it, and then does fixup
 654 * on the sd->s_type.
 655 *
 656 * We could, perhaps, tweak our parent's ->mkdir for a minute and
 657 * try using vfs_mkdir.  Just a thought.
 658 */
 659static int create_default_group(struct config_group *parent_group,
 660                                struct config_group *group)
 661{
 662        int ret;
 663        struct configfs_dirent *sd;
 664        /* We trust the caller holds a reference to parent */
 665        struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
 666
 667        if (!group->cg_item.ci_name)
 668                group->cg_item.ci_name = group->cg_item.ci_namebuf;
 669
 670        ret = -ENOMEM;
 671        child = d_alloc_name(parent, group->cg_item.ci_name);
 672        if (child) {
 673                d_add(child, NULL);
 674
 675                ret = configfs_attach_group(&parent_group->cg_item,
 676                                            &group->cg_item, child);
 677                if (!ret) {
 678                        sd = child->d_fsdata;
 679                        sd->s_type |= CONFIGFS_USET_DEFAULT;
 680                } else {
 681                        BUG_ON(child->d_inode);
 682                        d_drop(child);
 683                        dput(child);
 684                }
 685        }
 686
 687        return ret;
 688}
 689
 690static int populate_groups(struct config_group *group)
 691{
 692        struct config_group *new_group;
 693        int ret = 0;
 694        int i;
 695
 696        if (group->default_groups) {
 697                for (i = 0; group->default_groups[i]; i++) {
 698                        new_group = group->default_groups[i];
 699
 700                        ret = create_default_group(group, new_group);
 701                        if (ret) {
 702                                detach_groups(group);
 703                                break;
 704                        }
 705                }
 706        }
 707
 708        return ret;
 709}
 710
 711/*
 712 * All of link_obj/unlink_obj/link_group/unlink_group require that
 713 * subsys->su_mutex is held.
 714 */
 715
 716static void unlink_obj(struct config_item *item)
 717{
 718        struct config_group *group;
 719
 720        group = item->ci_group;
 721        if (group) {
 722                list_del_init(&item->ci_entry);
 723
 724                item->ci_group = NULL;
 725                item->ci_parent = NULL;
 726
 727                /* Drop the reference for ci_entry */
 728                config_item_put(item);
 729
 730                /* Drop the reference for ci_parent */
 731                config_group_put(group);
 732        }
 733}
 734
 735static void link_obj(struct config_item *parent_item, struct config_item *item)
 736{
 737        /*
 738         * Parent seems redundant with group, but it makes certain
 739         * traversals much nicer.
 740         */
 741        item->ci_parent = parent_item;
 742
 743        /*
 744         * We hold a reference on the parent for the child's ci_parent
 745         * link.
 746         */
 747        item->ci_group = config_group_get(to_config_group(parent_item));
 748        list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
 749
 750        /*
 751         * We hold a reference on the child for ci_entry on the parent's
 752         * cg_children
 753         */
 754        config_item_get(item);
 755}
 756
 757static void unlink_group(struct config_group *group)
 758{
 759        int i;
 760        struct config_group *new_group;
 761
 762        if (group->default_groups) {
 763                for (i = 0; group->default_groups[i]; i++) {
 764                        new_group = group->default_groups[i];
 765                        unlink_group(new_group);
 766                }
 767        }
 768
 769        group->cg_subsys = NULL;
 770        unlink_obj(&group->cg_item);
 771}
 772
 773static void link_group(struct config_group *parent_group, struct config_group *group)
 774{
 775        int i;
 776        struct config_group *new_group;
 777        struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
 778
 779        link_obj(&parent_group->cg_item, &group->cg_item);
 780
 781        if (parent_group->cg_subsys)
 782                subsys = parent_group->cg_subsys;
 783        else if (configfs_is_root(&parent_group->cg_item))
 784                subsys = to_configfs_subsystem(group);
 785        else
 786                BUG();
 787        group->cg_subsys = subsys;
 788
 789        if (group->default_groups) {
 790                for (i = 0; group->default_groups[i]; i++) {
 791                        new_group = group->default_groups[i];
 792                        link_group(group, new_group);
 793                }
 794        }
 795}
 796
 797/*
 798 * The goal is that configfs_attach_item() (and
 799 * configfs_attach_group()) can be called from either the VFS or this
 800 * module.  That is, they assume that the items have been created,
 801 * the dentry allocated, and the dcache is all ready to go.
 802 *
 803 * If they fail, they must clean up after themselves as if they
 804 * had never been called.  The caller (VFS or local function) will
 805 * handle cleaning up the dcache bits.
 806 *
 807 * configfs_detach_group() and configfs_detach_item() behave similarly on
 808 * the way out.  They assume that the proper semaphores are held, they
 809 * clean up the configfs items, and they expect their callers will
 810 * handle the dcache bits.
 811 */
 812static int configfs_attach_item(struct config_item *parent_item,
 813                                struct config_item *item,
 814                                struct dentry *dentry)
 815{
 816        int ret;
 817
 818        ret = configfs_create_dir(item, dentry);
 819        if (!ret) {
 820                ret = populate_attrs(item);
 821                if (ret) {
 822                        /*
 823                         * We are going to remove an inode and its dentry but
 824                         * the VFS may already have hit and used them. Thus,
 825                         * we must lock them as rmdir() would.
 826                         */
 827                        mutex_lock(&dentry->d_inode->i_mutex);
 828                        configfs_remove_dir(item);
 829                        dentry->d_inode->i_flags |= S_DEAD;
 830                        dont_mount(dentry);
 831                        mutex_unlock(&dentry->d_inode->i_mutex);
 832                        d_delete(dentry);
 833                }
 834        }
 835
 836        return ret;
 837}
 838
 839/* Caller holds the mutex of the item's inode */
 840static void configfs_detach_item(struct config_item *item)
 841{
 842        detach_attrs(item);
 843        configfs_remove_dir(item);
 844}
 845
 846static int configfs_attach_group(struct config_item *parent_item,
 847                                 struct config_item *item,
 848                                 struct dentry *dentry)
 849{
 850        int ret;
 851        struct configfs_dirent *sd;
 852
 853        ret = configfs_attach_item(parent_item, item, dentry);
 854        if (!ret) {
 855                sd = dentry->d_fsdata;
 856                sd->s_type |= CONFIGFS_USET_DIR;
 857
 858                /*
 859                 * FYI, we're faking mkdir in populate_groups()
 860                 * We must lock the group's inode to avoid races with the VFS
 861                 * which can already hit the inode and try to add/remove entries
 862                 * under it.
 863                 *
 864                 * We must also lock the inode to remove it safely in case of
 865                 * error, as rmdir() would.
 866                 */
 867                mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
 868                configfs_adjust_dir_dirent_depth_before_populate(sd);
 869                ret = populate_groups(to_config_group(item));
 870                if (ret) {
 871                        configfs_detach_item(item);
 872                        dentry->d_inode->i_flags |= S_DEAD;
 873                        dont_mount(dentry);
 874                }
 875                configfs_adjust_dir_dirent_depth_after_populate(sd);
 876                mutex_unlock(&dentry->d_inode->i_mutex);
 877                if (ret)
 878                        d_delete(dentry);
 879        }
 880
 881        return ret;
 882}
 883
 884/* Caller holds the mutex of the group's inode */
 885static void configfs_detach_group(struct config_item *item)
 886{
 887        detach_groups(to_config_group(item));
 888        configfs_detach_item(item);
 889}
 890
 891/*
 892 * After the item has been detached from the filesystem view, we are
 893 * ready to tear it out of the hierarchy.  Notify the client before
 894 * we do that so they can perform any cleanup that requires
 895 * navigating the hierarchy.  A client does not need to provide this
 896 * callback.  The subsystem semaphore MUST be held by the caller, and
 897 * references must be valid for both items.  It also assumes the
 898 * caller has validated ci_type.
 899 */
 900static void client_disconnect_notify(struct config_item *parent_item,
 901                                     struct config_item *item)
 902{
 903        struct config_item_type *type;
 904
 905        type = parent_item->ci_type;
 906        BUG_ON(!type);
 907
 908        if (type->ct_group_ops && type->ct_group_ops->disconnect_notify)
 909                type->ct_group_ops->disconnect_notify(to_config_group(parent_item),
 910                                                      item);
 911}
 912
 913/*
 914 * Drop the initial reference from make_item()/make_group()
 915 * This function assumes that reference is held on item
 916 * and that item holds a valid reference to the parent.  Also, it
 917 * assumes the caller has validated ci_type.
 918 */
 919static void client_drop_item(struct config_item *parent_item,
 920                             struct config_item *item)
 921{
 922        struct config_item_type *type;
 923
 924        type = parent_item->ci_type;
 925        BUG_ON(!type);
 926
 927        /*
 928         * If ->drop_item() exists, it is responsible for the
 929         * config_item_put().
 930         */
 931        if (type->ct_group_ops && type->ct_group_ops->drop_item)
 932                type->ct_group_ops->drop_item(to_config_group(parent_item),
 933                                              item);
 934        else
 935                config_item_put(item);
 936}
 937
 938#ifdef DEBUG
 939static void configfs_dump_one(struct configfs_dirent *sd, int level)
 940{
 941        printk(KERN_INFO "%*s\"%s\":\n", level, " ", configfs_get_name(sd));
 942
 943#define type_print(_type) if (sd->s_type & _type) printk(KERN_INFO "%*s %s\n", level, " ", #_type);
 944        type_print(CONFIGFS_ROOT);
 945        type_print(CONFIGFS_DIR);
 946        type_print(CONFIGFS_ITEM_ATTR);
 947        type_print(CONFIGFS_ITEM_LINK);
 948        type_print(CONFIGFS_USET_DIR);
 949        type_print(CONFIGFS_USET_DEFAULT);
 950        type_print(CONFIGFS_USET_DROPPING);
 951#undef type_print
 952}
 953
 954static int configfs_dump(struct configfs_dirent *sd, int level)
 955{
 956        struct configfs_dirent *child_sd;
 957        int ret = 0;
 958
 959        configfs_dump_one(sd, level);
 960
 961        if (!(sd->s_type & (CONFIGFS_DIR|CONFIGFS_ROOT)))
 962                return 0;
 963
 964        list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
 965                ret = configfs_dump(child_sd, level + 2);
 966                if (ret)
 967                        break;
 968        }
 969
 970        return ret;
 971}
 972#endif
 973
 974
 975/*
 976 * configfs_depend_item() and configfs_undepend_item()
 977 *
 978 * WARNING: Do not call these from a configfs callback!
 979 *
 980 * This describes these functions and their helpers.
 981 *
 982 * Allow another kernel system to depend on a config_item.  If this
 983 * happens, the item cannot go away until the dependent can live without
 984 * it.  The idea is to give client modules as simple an interface as
 985 * possible.  When a system asks them to depend on an item, they just
 986 * call configfs_depend_item().  If the item is live and the client
 987 * driver is in good shape, we'll happily do the work for them.
 988 *
 989 * Why is the locking complex?  Because configfs uses the VFS to handle
 990 * all locking, but this function is called outside the normal
 991 * VFS->configfs path.  So it must take VFS locks to prevent the
 992 * VFS->configfs stuff (configfs_mkdir(), configfs_rmdir(), etc).  This is
 993 * why you can't call these functions underneath configfs callbacks.
 994 *
 995 * Note, btw, that this can be called at *any* time, even when a configfs
 996 * subsystem isn't registered, or when configfs is loading or unloading.
 997 * Just like configfs_register_subsystem().  So we take the same
 998 * precautions.  We pin the filesystem.  We lock configfs_dirent_lock.
 999 * If we can find the target item in the
1000 * configfs tree, it must be part of the subsystem tree as well, so we
1001 * do not need the subsystem semaphore.  Holding configfs_dirent_lock helps
1002 * locking out mkdir() and rmdir(), who might be racing us.
1003 */
1004
1005/*
1006 * configfs_depend_prep()
1007 *
1008 * Only subdirectories count here.  Files (CONFIGFS_NOT_PINNED) are
1009 * attributes.  This is similar but not the same to configfs_detach_prep().
1010 * Note that configfs_detach_prep() expects the parent to be locked when it
1011 * is called, but we lock the parent *inside* configfs_depend_prep().  We
1012 * do that so we can unlock it if we find nothing.
1013 *
1014 * Here we do a depth-first search of the dentry hierarchy looking for
1015 * our object.
1016 * We deliberately ignore items tagged as dropping since they are virtually
1017 * dead, as well as items in the middle of attachment since they virtually
1018 * do not exist yet. This completes the locking out of racing mkdir() and
1019 * rmdir().
1020 * Note: subdirectories in the middle of attachment start with s_type =
1021 * CONFIGFS_DIR|CONFIGFS_USET_CREATING set by create_dir().  When
1022 * CONFIGFS_USET_CREATING is set, we ignore the item.  The actual set of
1023 * s_type is in configfs_new_dirent(), which has configfs_dirent_lock.
1024 *
1025 * If the target is not found, -ENOENT is bubbled up.
1026 *
1027 * This adds a requirement that all config_items be unique!
1028 *
1029 * This is recursive.  There isn't
1030 * much on the stack, though, so folks that need this function - be careful
1031 * about your stack!  Patches will be accepted to make it iterative.
1032 */
1033static int configfs_depend_prep(struct dentry *origin,
1034                                struct config_item *target)
1035{
1036        struct configfs_dirent *child_sd, *sd;
1037        int ret = 0;
1038
1039        BUG_ON(!origin || !origin->d_fsdata);
1040        sd = origin->d_fsdata;
1041
1042        if (sd->s_element == target)  /* Boo-yah */
1043                goto out;
1044
1045        list_for_each_entry(child_sd, &sd->s_children, s_sibling) {
1046                if ((child_sd->s_type & CONFIGFS_DIR) &&
1047                    !(child_sd->s_type & CONFIGFS_USET_DROPPING) &&
1048                    !(child_sd->s_type & CONFIGFS_USET_CREATING)) {
1049                        ret = configfs_depend_prep(child_sd->s_dentry,
1050                                                   target);
1051                        if (!ret)
1052                                goto out;  /* Child path boo-yah */
1053                }
1054        }
1055
1056        /* We looped all our children and didn't find target */
1057        ret = -ENOENT;
1058
1059out:
1060        return ret;
1061}
1062
1063int configfs_depend_item(struct configfs_subsystem *subsys,
1064                         struct config_item *target)
1065{
1066        int ret;
1067        struct configfs_dirent *p, *root_sd, *subsys_sd = NULL;
1068        struct config_item *s_item = &subsys->su_group.cg_item;
1069        struct dentry *root;
1070
1071        /*
1072         * Pin the configfs filesystem.  This means we can safely access
1073         * the root of the configfs filesystem.
1074         */
1075        root = configfs_pin_fs();
1076        if (IS_ERR(root))
1077                return PTR_ERR(root);
1078
1079        /*
1080         * Next, lock the root directory.  We're going to check that the
1081         * subsystem is really registered, and so we need to lock out
1082         * configfs_[un]register_subsystem().
1083         */
1084        mutex_lock(&root->d_inode->i_mutex);
1085
1086        root_sd = root->d_fsdata;
1087
1088        list_for_each_entry(p, &root_sd->s_children, s_sibling) {
1089                if (p->s_type & CONFIGFS_DIR) {
1090                        if (p->s_element == s_item) {
1091                                subsys_sd = p;
1092                                break;
1093                        }
1094                }
1095        }
1096
1097        if (!subsys_sd) {
1098                ret = -ENOENT;
1099                goto out_unlock_fs;
1100        }
1101
1102        /* Ok, now we can trust subsys/s_item */
1103
1104        spin_lock(&configfs_dirent_lock);
1105        /* Scan the tree, return 0 if found */
1106        ret = configfs_depend_prep(subsys_sd->s_dentry, target);
1107        if (ret)
1108                goto out_unlock_dirent_lock;
1109
1110        /*
1111         * We are sure that the item is not about to be removed by rmdir(), and
1112         * not in the middle of attachment by mkdir().
1113         */
1114        p = target->ci_dentry->d_fsdata;
1115        p->s_dependent_count += 1;
1116
1117out_unlock_dirent_lock:
1118        spin_unlock(&configfs_dirent_lock);
1119out_unlock_fs:
1120        mutex_unlock(&root->d_inode->i_mutex);
1121
1122        /*
1123         * If we succeeded, the fs is pinned via other methods.  If not,
1124         * we're done with it anyway.  So release_fs() is always right.
1125         */
1126        configfs_release_fs();
1127
1128        return ret;
1129}
1130EXPORT_SYMBOL(configfs_depend_item);
1131
1132/*
1133 * Release the dependent linkage.  This is much simpler than
1134 * configfs_depend_item() because we know that that the client driver is
1135 * pinned, thus the subsystem is pinned, and therefore configfs is pinned.
1136 */
1137void configfs_undepend_item(struct configfs_subsystem *subsys,
1138                            struct config_item *target)
1139{
1140        struct configfs_dirent *sd;
1141
1142        /*
1143         * Since we can trust everything is pinned, we just need
1144         * configfs_dirent_lock.
1145         */
1146        spin_lock(&configfs_dirent_lock);
1147
1148        sd = target->ci_dentry->d_fsdata;
1149        BUG_ON(sd->s_dependent_count < 1);
1150
1151        sd->s_dependent_count -= 1;
1152
1153        /*
1154         * After this unlock, we cannot trust the item to stay alive!
1155         * DO NOT REFERENCE item after this unlock.
1156         */
1157        spin_unlock(&configfs_dirent_lock);
1158}
1159EXPORT_SYMBOL(configfs_undepend_item);
1160
1161static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
1162{
1163        int ret = 0;
1164        int module_got = 0;
1165        struct config_group *group = NULL;
1166        struct config_item *item = NULL;
1167        struct config_item *parent_item;
1168        struct configfs_subsystem *subsys;
1169        struct configfs_dirent *sd;
1170        struct config_item_type *type;
1171        struct module *subsys_owner = NULL, *new_item_owner = NULL;
1172        char *name;
1173
1174        sd = dentry->d_parent->d_fsdata;
1175
1176        /*
1177         * Fake invisibility if dir belongs to a group/default groups hierarchy
1178         * being attached
1179         */
1180        if (!configfs_dirent_is_ready(sd)) {
1181                ret = -ENOENT;
1182                goto out;
1183        }
1184
1185        if (!(sd->s_type & CONFIGFS_USET_DIR)) {
1186                ret = -EPERM;
1187                goto out;
1188        }
1189
1190        /* Get a working ref for the duration of this function */
1191        parent_item = configfs_get_config_item(dentry->d_parent);
1192        type = parent_item->ci_type;
1193        subsys = to_config_group(parent_item)->cg_subsys;
1194        BUG_ON(!subsys);
1195
1196        if (!type || !type->ct_group_ops ||
1197            (!type->ct_group_ops->make_group &&
1198             !type->ct_group_ops->make_item)) {
1199                ret = -EPERM;  /* Lack-of-mkdir returns -EPERM */
1200                goto out_put;
1201        }
1202
1203        /*
1204         * The subsystem may belong to a different module than the item
1205         * being created.  We don't want to safely pin the new item but
1206         * fail to pin the subsystem it sits under.
1207         */
1208        if (!subsys->su_group.cg_item.ci_type) {
1209                ret = -EINVAL;
1210                goto out_put;
1211        }
1212        subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1213        if (!try_module_get(subsys_owner)) {
1214                ret = -EINVAL;
1215                goto out_put;
1216        }
1217
1218        name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
1219        if (!name) {
1220                ret = -ENOMEM;
1221                goto out_subsys_put;
1222        }
1223
1224        snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
1225
1226        mutex_lock(&subsys->su_mutex);
1227        if (type->ct_group_ops->make_group) {
1228                group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
1229                if (!group)
1230                        group = ERR_PTR(-ENOMEM);
1231                if (!IS_ERR(group)) {
1232                        link_group(to_config_group(parent_item), group);
1233                        item = &group->cg_item;
1234                } else
1235                        ret = PTR_ERR(group);
1236        } else {
1237                item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
1238                if (!item)
1239                        item = ERR_PTR(-ENOMEM);
1240                if (!IS_ERR(item))
1241                        link_obj(parent_item, item);
1242                else
1243                        ret = PTR_ERR(item);
1244        }
1245        mutex_unlock(&subsys->su_mutex);
1246
1247        kfree(name);
1248        if (ret) {
1249                /*
1250                 * If ret != 0, then link_obj() was never called.
1251                 * There are no extra references to clean up.
1252                 */
1253                goto out_subsys_put;
1254        }
1255
1256        /*
1257         * link_obj() has been called (via link_group() for groups).
1258         * From here on out, errors must clean that up.
1259         */
1260
1261        type = item->ci_type;
1262        if (!type) {
1263                ret = -EINVAL;
1264                goto out_unlink;
1265        }
1266
1267        new_item_owner = type->ct_owner;
1268        if (!try_module_get(new_item_owner)) {
1269                ret = -EINVAL;
1270                goto out_unlink;
1271        }
1272
1273        /*
1274         * I hate doing it this way, but if there is
1275         * an error,  module_put() probably should
1276         * happen after any cleanup.
1277         */
1278        module_got = 1;
1279
1280        /*
1281         * Make racing rmdir() fail if it did not tag parent with
1282         * CONFIGFS_USET_DROPPING
1283         * Note: if CONFIGFS_USET_DROPPING is already set, attach_group() will
1284         * fail and let rmdir() terminate correctly
1285         */
1286        spin_lock(&configfs_dirent_lock);
1287        /* This will make configfs_detach_prep() fail */
1288        sd->s_type |= CONFIGFS_USET_IN_MKDIR;
1289        spin_unlock(&configfs_dirent_lock);
1290
1291        if (group)
1292                ret = configfs_attach_group(parent_item, item, dentry);
1293        else
1294                ret = configfs_attach_item(parent_item, item, dentry);
1295
1296        spin_lock(&configfs_dirent_lock);
1297        sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
1298        if (!ret)
1299                configfs_dir_set_ready(dentry->d_fsdata);
1300        spin_unlock(&configfs_dirent_lock);
1301
1302out_unlink:
1303        if (ret) {
1304                /* Tear down everything we built up */
1305                mutex_lock(&subsys->su_mutex);
1306
1307                client_disconnect_notify(parent_item, item);
1308                if (group)
1309                        unlink_group(group);
1310                else
1311                        unlink_obj(item);
1312                client_drop_item(parent_item, item);
1313
1314                mutex_unlock(&subsys->su_mutex);
1315
1316                if (module_got)
1317                        module_put(new_item_owner);
1318        }
1319
1320out_subsys_put:
1321        if (ret)
1322                module_put(subsys_owner);
1323
1324out_put:
1325        /*
1326         * link_obj()/link_group() took a reference from child->parent,
1327         * so the parent is safely pinned.  We can drop our working
1328         * reference.
1329         */
1330        config_item_put(parent_item);
1331
1332out:
1333        return ret;
1334}
1335
1336static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
1337{
1338        struct config_item *parent_item;
1339        struct config_item *item;
1340        struct configfs_subsystem *subsys;
1341        struct configfs_dirent *sd;
1342        struct module *subsys_owner = NULL, *dead_item_owner = NULL;
1343        int ret;
1344
1345        sd = dentry->d_fsdata;
1346        if (sd->s_type & CONFIGFS_USET_DEFAULT)
1347                return -EPERM;
1348
1349        /* Get a working ref until we have the child */
1350        parent_item = configfs_get_config_item(dentry->d_parent);
1351        subsys = to_config_group(parent_item)->cg_subsys;
1352        BUG_ON(!subsys);
1353
1354        if (!parent_item->ci_type) {
1355                config_item_put(parent_item);
1356                return -EINVAL;
1357        }
1358
1359        /* configfs_mkdir() shouldn't have allowed this */
1360        BUG_ON(!subsys->su_group.cg_item.ci_type);
1361        subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
1362
1363        /*
1364         * Ensure that no racing symlink() will make detach_prep() fail while
1365         * the new link is temporarily attached
1366         */
1367        do {
1368                struct mutex *wait_mutex;
1369
1370                mutex_lock(&configfs_symlink_mutex);
1371                spin_lock(&configfs_dirent_lock);
1372                /*
1373                 * Here's where we check for dependents.  We're protected by
1374                 * configfs_dirent_lock.
1375                 * If no dependent, atomically tag the item as dropping.
1376                 */
1377                ret = sd->s_dependent_count ? -EBUSY : 0;
1378                if (!ret) {
1379                        ret = configfs_detach_prep(dentry, &wait_mutex);
1380                        if (ret)
1381                                configfs_detach_rollback(dentry);
1382                }
1383                spin_unlock(&configfs_dirent_lock);
1384                mutex_unlock(&configfs_symlink_mutex);
1385
1386                if (ret) {
1387                        if (ret != -EAGAIN) {
1388                                config_item_put(parent_item);
1389                                return ret;
1390                        }
1391
1392                        /* Wait until the racing operation terminates */
1393                        mutex_lock(wait_mutex);
1394                        mutex_unlock(wait_mutex);
1395                }
1396        } while (ret == -EAGAIN);
1397
1398        /* Get a working ref for the duration of this function */
1399        item = configfs_get_config_item(dentry);
1400
1401        /* Drop reference from above, item already holds one. */
1402        config_item_put(parent_item);
1403
1404        if (item->ci_type)
1405                dead_item_owner = item->ci_type->ct_owner;
1406
1407        if (sd->s_type & CONFIGFS_USET_DIR) {
1408                configfs_detach_group(item);
1409
1410                mutex_lock(&subsys->su_mutex);
1411                client_disconnect_notify(parent_item, item);
1412                unlink_group(to_config_group(item));
1413        } else {
1414                configfs_detach_item(item);
1415
1416                mutex_lock(&subsys->su_mutex);
1417                client_disconnect_notify(parent_item, item);
1418                unlink_obj(item);
1419        }
1420
1421        client_drop_item(parent_item, item);
1422        mutex_unlock(&subsys->su_mutex);
1423
1424        /* Drop our reference from above */
1425        config_item_put(item);
1426
1427        module_put(dead_item_owner);
1428        module_put(subsys_owner);
1429
1430        return 0;
1431}
1432
1433const struct inode_operations configfs_dir_inode_operations = {
1434        .mkdir          = configfs_mkdir,
1435        .rmdir          = configfs_rmdir,
1436        .symlink        = configfs_symlink,
1437        .unlink         = configfs_unlink,
1438        .lookup         = configfs_lookup,
1439        .setattr        = configfs_setattr,
1440};
1441
1442const struct inode_operations configfs_root_inode_operations = {
1443        .lookup         = configfs_lookup,
1444        .setattr        = configfs_setattr,
1445};
1446
1447#if 0
1448int configfs_rename_dir(struct config_item * item, const char *new_name)
1449{
1450        int error = 0;
1451        struct dentry * new_dentry, * parent;
1452
1453        if (!strcmp(config_item_name(item), new_name))
1454                return -EINVAL;
1455
1456        if (!item->parent)
1457                return -EINVAL;
1458
1459        down_write(&configfs_rename_sem);
1460        parent = item->parent->dentry;
1461
1462        mutex_lock(&parent->d_inode->i_mutex);
1463
1464        new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
1465        if (!IS_ERR(new_dentry)) {
1466                if (!new_dentry->d_inode) {
1467                        error = config_item_set_name(item, "%s", new_name);
1468                        if (!error) {
1469                                d_add(new_dentry, NULL);
1470                                d_move(item->dentry, new_dentry);
1471                        }
1472                        else
1473                                d_delete(new_dentry);
1474                } else
1475                        error = -EEXIST;
1476                dput(new_dentry);
1477        }
1478        mutex_unlock(&parent->d_inode->i_mutex);
1479        up_write(&configfs_rename_sem);
1480
1481        return error;
1482}
1483#endif
1484
1485static int configfs_dir_open(struct inode *inode, struct file *file)
1486{
1487        struct dentry * dentry = file->f_path.dentry;
1488        struct configfs_dirent * parent_sd = dentry->d_fsdata;
1489        int err;
1490
1491        mutex_lock(&dentry->d_inode->i_mutex);
1492        /*
1493         * Fake invisibility if dir belongs to a group/default groups hierarchy
1494         * being attached
1495         */
1496        err = -ENOENT;
1497        if (configfs_dirent_is_ready(parent_sd)) {
1498                file->private_data = configfs_new_dirent(parent_sd, NULL, 0);
1499                if (IS_ERR(file->private_data))
1500                        err = PTR_ERR(file->private_data);
1501                else
1502                        err = 0;
1503        }
1504        mutex_unlock(&dentry->d_inode->i_mutex);
1505
1506        return err;
1507}
1508
1509static int configfs_dir_close(struct inode *inode, struct file *file)
1510{
1511        struct dentry * dentry = file->f_path.dentry;
1512        struct configfs_dirent * cursor = file->private_data;
1513
1514        mutex_lock(&dentry->d_inode->i_mutex);
1515        spin_lock(&configfs_dirent_lock);
1516        list_del_init(&cursor->s_sibling);
1517        spin_unlock(&configfs_dirent_lock);
1518        mutex_unlock(&dentry->d_inode->i_mutex);
1519
1520        release_configfs_dirent(cursor);
1521
1522        return 0;
1523}
1524
1525/* Relationship between s_mode and the DT_xxx types */
1526static inline unsigned char dt_type(struct configfs_dirent *sd)
1527{
1528        return (sd->s_mode >> 12) & 15;
1529}
1530
1531static int configfs_readdir(struct file *file, struct dir_context *ctx)
1532{
1533        struct dentry *dentry = file->f_path.dentry;
1534        struct super_block *sb = dentry->d_sb;
1535        struct configfs_dirent * parent_sd = dentry->d_fsdata;
1536        struct configfs_dirent *cursor = file->private_data;
1537        struct list_head *p, *q = &cursor->s_sibling;
1538        ino_t ino = 0;
1539
1540        if (!dir_emit_dots(file, ctx))
1541                return 0;
1542        if (ctx->pos == 2) {
1543                spin_lock(&configfs_dirent_lock);
1544                list_move(q, &parent_sd->s_children);
1545                spin_unlock(&configfs_dirent_lock);
1546        }
1547        for (p = q->next; p != &parent_sd->s_children; p = p->next) {
1548                struct configfs_dirent *next;
1549                const char *name;
1550                int len;
1551                struct inode *inode = NULL;
1552
1553                next = list_entry(p, struct configfs_dirent, s_sibling);
1554                if (!next->s_element)
1555                        continue;
1556
1557                name = configfs_get_name(next);
1558                len = strlen(name);
1559
1560                /*
1561                 * We'll have a dentry and an inode for
1562                 * PINNED items and for open attribute
1563                 * files.  We lock here to prevent a race
1564                 * with configfs_d_iput() clearing
1565                 * s_dentry before calling iput().
1566                 *
1567                 * Why do we go to the trouble?  If
1568                 * someone has an attribute file open,
1569                 * the inode number should match until
1570                 * they close it.  Beyond that, we don't
1571                 * care.
1572                 */
1573                spin_lock(&configfs_dirent_lock);
1574                dentry = next->s_dentry;
1575                if (dentry)
1576                        inode = dentry->d_inode;
1577                if (inode)
1578                        ino = inode->i_ino;
1579                spin_unlock(&configfs_dirent_lock);
1580                if (!inode)
1581                        ino = iunique(sb, 2);
1582
1583                if (!dir_emit(ctx, name, len, ino, dt_type(next)))
1584                        return 0;
1585
1586                spin_lock(&configfs_dirent_lock);
1587                list_move(q, p);
1588                spin_unlock(&configfs_dirent_lock);
1589                p = q;
1590                ctx->pos++;
1591        }
1592        return 0;
1593}
1594
1595static loff_t configfs_dir_lseek(struct file *file, loff_t offset, int whence)
1596{
1597        struct dentry * dentry = file->f_path.dentry;
1598
1599        mutex_lock(&dentry->d_inode->i_mutex);
1600        switch (whence) {
1601                case 1:
1602                        offset += file->f_pos;
1603                case 0:
1604                        if (offset >= 0)
1605                                break;
1606                default:
1607                        mutex_unlock(&file_inode(file)->i_mutex);
1608                        return -EINVAL;
1609        }
1610        if (offset != file->f_pos) {
1611                file->f_pos = offset;
1612                if (file->f_pos >= 2) {
1613                        struct configfs_dirent *sd = dentry->d_fsdata;
1614                        struct configfs_dirent *cursor = file->private_data;
1615                        struct list_head *p;
1616                        loff_t n = file->f_pos - 2;
1617
1618                        spin_lock(&configfs_dirent_lock);
1619                        list_del(&cursor->s_sibling);
1620                        p = sd->s_children.next;
1621                        while (n && p != &sd->s_children) {
1622                                struct configfs_dirent *next;
1623                                next = list_entry(p, struct configfs_dirent,
1624                                                   s_sibling);
1625                                if (next->s_element)
1626                                        n--;
1627                                p = p->next;
1628                        }
1629                        list_add_tail(&cursor->s_sibling, p);
1630                        spin_unlock(&configfs_dirent_lock);
1631                }
1632        }
1633        mutex_unlock(&dentry->d_inode->i_mutex);
1634        return offset;
1635}
1636
1637const struct file_operations configfs_dir_operations = {
1638        .open           = configfs_dir_open,
1639        .release        = configfs_dir_close,
1640        .llseek         = configfs_dir_lseek,
1641        .read           = generic_read_dir,
1642        .iterate        = configfs_readdir,
1643};
1644
1645int configfs_register_subsystem(struct configfs_subsystem *subsys)
1646{
1647        int err;
1648        struct config_group *group = &subsys->su_group;
1649        struct dentry *dentry;
1650        struct dentry *root;
1651        struct configfs_dirent *sd;
1652
1653        root = configfs_pin_fs();
1654        if (IS_ERR(root))
1655                return PTR_ERR(root);
1656
1657        if (!group->cg_item.ci_name)
1658                group->cg_item.ci_name = group->cg_item.ci_namebuf;
1659
1660        sd = root->d_fsdata;
1661        link_group(to_config_group(sd->s_element), group);
1662
1663        mutex_lock_nested(&root->d_inode->i_mutex, I_MUTEX_PARENT);
1664
1665        err = -ENOMEM;
1666        dentry = d_alloc_name(root, group->cg_item.ci_name);
1667        if (dentry) {
1668                d_add(dentry, NULL);
1669
1670                err = configfs_attach_group(sd->s_element, &group->cg_item,
1671                                            dentry);
1672                if (err) {
1673                        BUG_ON(dentry->d_inode);
1674                        d_drop(dentry);
1675                        dput(dentry);
1676                } else {
1677                        spin_lock(&configfs_dirent_lock);
1678                        configfs_dir_set_ready(dentry->d_fsdata);
1679                        spin_unlock(&configfs_dirent_lock);
1680                }
1681        }
1682
1683        mutex_unlock(&root->d_inode->i_mutex);
1684
1685        if (err) {
1686                unlink_group(group);
1687                configfs_release_fs();
1688        }
1689
1690        return err;
1691}
1692
1693void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
1694{
1695        struct config_group *group = &subsys->su_group;
1696        struct dentry *dentry = group->cg_item.ci_dentry;
1697        struct dentry *root = dentry->d_sb->s_root;
1698
1699        if (dentry->d_parent != root) {
1700                printk(KERN_ERR "configfs: Tried to unregister non-subsystem!\n");
1701                return;
1702        }
1703
1704        mutex_lock_nested(&root->d_inode->i_mutex,
1705                          I_MUTEX_PARENT);
1706        mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
1707        mutex_lock(&configfs_symlink_mutex);
1708        spin_lock(&configfs_dirent_lock);
1709        if (configfs_detach_prep(dentry, NULL)) {
1710                printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n");
1711        }
1712        spin_unlock(&configfs_dirent_lock);
1713        mutex_unlock(&configfs_symlink_mutex);
1714        configfs_detach_group(&group->cg_item);
1715        dentry->d_inode->i_flags |= S_DEAD;
1716        dont_mount(dentry);
1717        mutex_unlock(&dentry->d_inode->i_mutex);
1718
1719        d_delete(dentry);
1720
1721        mutex_unlock(&root->d_inode->i_mutex);
1722
1723        dput(dentry);
1724
1725        unlink_group(group);
1726        configfs_release_fs();
1727}
1728
1729EXPORT_SYMBOL(configfs_register_subsystem);
1730EXPORT_SYMBOL(configfs_unregister_subsystem);
1731
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