fs/configfs/dir.c

   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
  34 #include <linux/configfs.h>
  35 #include "configfs_internal.h"
  36
  37 DECLARE_RWSEM(configfs_rename_sem);
  38
  39 static void configfs_d_iput(struct dentry * dentry,
  40                             struct inode * inode)
  41 {
  42         struct configfs_dirent * sd = dentry->d_fsdata;
  43
  44         if (sd) {
  45                 BUG_ON(sd->s_dentry != dentry);
  46                 sd->s_dentry = NULL;
  47                 configfs_put(sd);
  48         }
  49         iput(inode);
  50 }
  51
  52 /*
  53  * We _must_ delete our dentries on last dput, as the chain-to-parent
  54  * behavior is required to clear the parents of default_groups.
  55  */
  56 static int configfs_d_delete(struct dentry *dentry)
  57 {
  58         return 1;
  59 }
  60
  61 static struct dentry_operations configfs_dentry_ops = {
  62         .d_iput         = configfs_d_iput,
  63         /* simple_delete_dentry() isn't exported */
  64         .d_delete       = configfs_d_delete,
  65 };
  66
  67 /*
  68  * Allocates a new configfs_dirent and links it to the parent configfs_dirent
  69  */
  70 static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent * parent_sd,
  71                                                 void * element)
  72 {
  73         struct configfs_dirent * sd;
  74
  75         sd = kmem_cache_alloc(configfs_dir_cachep, GFP_KERNEL);
  76         if (!sd)
  77                 return NULL;
  78
  79         memset(sd, 0, sizeof(*sd));
  80         atomic_set(&sd->s_count, 1);
  81         INIT_LIST_HEAD(&sd->s_links);
  82         INIT_LIST_HEAD(&sd->s_children);
  83         list_add(&sd->s_sibling, &parent_sd->s_children);
  84         sd->s_element = element;
  85
  86         return sd;
  87 }
  88
  89 int configfs_make_dirent(struct configfs_dirent * parent_sd,
  90                          struct dentry * dentry, void * element,
  91                          umode_t mode, int type)
  92 {
  93         struct configfs_dirent * sd;
  94
  95         sd = configfs_new_dirent(parent_sd, element);
  96         if (!sd)
  97                 return -ENOMEM;
  98
  99         sd->s_mode = mode;
 100         sd->s_type = type;
 101         sd->s_dentry = dentry;
 102         if (dentry) {
 103                 dentry->d_fsdata = configfs_get(sd);
 104                 dentry->d_op = &configfs_dentry_ops;
 105         }
 106
 107         return 0;
 108 }
 109
 110 static int init_dir(struct inode * inode)
 111 {
 112         inode->i_op = &configfs_dir_inode_operations;
 113         inode->i_fop = &configfs_dir_operations;
 114
 115         /* directory inodes start off with i_nlink == 2 (for "." entry) */
 116         inode->i_nlink++;
 117         return 0;
 118 }
 119
 120 static int init_file(struct inode * inode)
 121 {
 122         inode->i_size = PAGE_SIZE;
 123         inode->i_fop = &configfs_file_operations;
 124         return 0;
 125 }
 126
 127 static int init_symlink(struct inode * inode)
 128 {
 129         inode->i_op = &configfs_symlink_inode_operations;
 130         return 0;
 131 }
 132
 133 static int create_dir(struct config_item * k, struct dentry * p,
 134                       struct dentry * d)
 135 {
 136         int error;
 137         umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
 138
 139         error = configfs_make_dirent(p->d_fsdata, d, k, mode,
 140                                      CONFIGFS_DIR);
 141         if (!error) {
 142                 error = configfs_create(d, mode, init_dir);
 143                 if (!error) {
 144                         p->d_inode->i_nlink++;
 145                         (d)->d_op = &configfs_dentry_ops;
 146                 } else {
 147                         struct configfs_dirent *sd = d->d_fsdata;
 148                         if (sd) {
 149                                 list_del_init(&sd->s_sibling);
 150                                 configfs_put(sd);
 151                         }
 152                 }
 153         }
 154         return error;
 155 }
 156
 157
 158 /**
 159  *      configfs_create_dir - create a directory for an config_item.
 160  *      @item:          config_itemwe're creating directory for.
 161  *      @dentry:        config_item's dentry.
 162  */
 163
 164 static int configfs_create_dir(struct config_item * item, struct dentry *dentry)
 165 {
 166         struct dentry * parent;
 167         int error = 0;
 168
 169         BUG_ON(!item);
 170
 171         if (item->ci_parent)
 172                 parent = item->ci_parent->ci_dentry;
 173         else if (configfs_mount && configfs_mount->mnt_sb)
 174                 parent = configfs_mount->mnt_sb->s_root;
 175         else
 176                 return -EFAULT;
 177
 178         error = create_dir(item,parent,dentry);
 179         if (!error)
 180                 item->ci_dentry = dentry;
 181         return error;
 182 }
 183
 184 int configfs_create_link(struct configfs_symlink *sl,
 185                          struct dentry *parent,
 186                          struct dentry *dentry)
 187 {
 188         int err = 0;
 189         umode_t mode = S_IFLNK | S_IRWXUGO;
 190
 191         err = configfs_make_dirent(parent->d_fsdata, dentry, sl, mode,
 192                                    CONFIGFS_ITEM_LINK);
 193         if (!err) {
 194                 err = configfs_create(dentry, mode, init_symlink);
 195                 if (!err)
 196                         dentry->d_op = &configfs_dentry_ops;
 197                 else {
 198                         struct configfs_dirent *sd = dentry->d_fsdata;
 199                         if (sd) {
 200                                 list_del_init(&sd->s_sibling);
 201                                 configfs_put(sd);
 202                         }
 203                 }
 204         }
 205         return err;
 206 }
 207
 208 static void remove_dir(struct dentry * d)
 209 {
 210         struct dentry * parent = dget(d->d_parent);
 211         struct configfs_dirent * sd;
 212
 213         sd = d->d_fsdata;
 214         list_del_init(&sd->s_sibling);
 215         configfs_put(sd);
 216         if (d->d_inode)
 217                 simple_rmdir(parent->d_inode,d);
 218
 219         pr_debug(" o %s removing done (%d)\n",d->d_name.name,
 220                  atomic_read(&d->d_count));
 221
 222         dput(parent);
 223 }
 224
 225 /**
 226  * configfs_remove_dir - remove an config_item's directory.
 227  * @item:       config_item we're removing.
 228  *
 229  * The only thing special about this is that we remove any files in
 230  * the directory before we remove the directory, and we've inlined
 231  * what used to be configfs_rmdir() below, instead of calling separately.
 232  */
 233
 234 static void configfs_remove_dir(struct config_item * item)
 235 {
 236         struct dentry * dentry = dget(item->ci_dentry);
 237
 238         if (!dentry)
 239                 return;
 240
 241         remove_dir(dentry);
 242         /**
 243          * Drop reference from dget() on entrance.
 244          */
 245         dput(dentry);
 246 }
 247
 248
 249 /* attaches attribute's configfs_dirent to the dentry corresponding to the
 250  * attribute file
 251  */
 252 static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
 253 {
 254         struct configfs_attribute * attr = sd->s_element;
 255         int error;
 256
 257         dentry->d_fsdata = configfs_get(sd);
 258         sd->s_dentry = dentry;
 259         error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG, init_file);
 260         if (error) {
 261                 configfs_put(sd);
 262                 return error;
 263         }
 264
 265         dentry->d_op = &configfs_dentry_ops;
 266         d_rehash(dentry);
 267
 268         return 0;
 269 }
 270
 271 static struct dentry * configfs_lookup(struct inode *dir,
 272                                        struct dentry *dentry,
 273                                        struct nameidata *nd)
 274 {
 275         struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
 276         struct configfs_dirent * sd;
 277         int found = 0;
 278         int err = 0;
 279
 280         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 281                 if (sd->s_type & CONFIGFS_NOT_PINNED) {
 282                         const unsigned char * name = configfs_get_name(sd);
 283
 284                         if (strcmp(name, dentry->d_name.name))
 285                                 continue;
 286
 287                         found = 1;
 288                         err = configfs_attach_attr(sd, dentry);
 289                         break;
 290                 }
 291         }
 292
 293         if (!found) {
 294                 /*
 295                  * If it doesn't exist and it isn't a NOT_PINNED item,
 296                  * it must be negative.
 297                  */
 298                 return simple_lookup(dir, dentry, nd);
 299         }
 300
 301         return ERR_PTR(err);
 302 }
 303
 304 /*
 305  * Only subdirectories count here.  Files (CONFIGFS_NOT_PINNED) are
 306  * attributes and are removed by rmdir().  We recurse, taking i_mutex
 307  * on all children that are candidates for default detach.  If the
 308  * result is clean, then configfs_detach_group() will handle dropping
 309  * i_mutex.  If there is an error, the caller will clean up the i_mutex
 310  * holders via configfs_detach_rollback().
 311  */
 312 static int configfs_detach_prep(struct dentry *dentry)
 313 {
 314         struct configfs_dirent *parent_sd = dentry->d_fsdata;
 315         struct configfs_dirent *sd;
 316         int ret;
 317
 318         ret = -EBUSY;
 319         if (!list_empty(&parent_sd->s_links))
 320                 goto out;
 321
 322         ret = 0;
 323         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 324                 if (sd->s_type & CONFIGFS_NOT_PINNED)
 325                         continue;
 326                 if (sd->s_type & CONFIGFS_USET_DEFAULT) {
 327                         mutex_lock(&sd->s_dentry->d_inode->i_mutex);
 328                         /* Mark that we've taken i_mutex */
 329                         sd->s_type |= CONFIGFS_USET_DROPPING;
 330
 331                         ret = configfs_detach_prep(sd->s_dentry);
 332                         if (!ret)
 333                                 continue;
 334                 } else
 335                         ret = -ENOTEMPTY;
 336
 337                 break;
 338         }
 339
 340 out:
 341         return ret;
 342 }
 343
 344 /*
 345  * Walk the tree, dropping i_mutex wherever CONFIGFS_USET_DROPPING is
 346  * set.
 347  */
 348 static void configfs_detach_rollback(struct dentry *dentry)
 349 {
 350         struct configfs_dirent *parent_sd = dentry->d_fsdata;
 351         struct configfs_dirent *sd;
 352
 353         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 354                 if (sd->s_type & CONFIGFS_USET_DEFAULT) {
 355                         configfs_detach_rollback(sd->s_dentry);
 356
 357                         if (sd->s_type & CONFIGFS_USET_DROPPING) {
 358                                 sd->s_type &= ~CONFIGFS_USET_DROPPING;
 359                                 mutex_unlock(&sd->s_dentry->d_inode->i_mutex);
 360                         }
 361                 }
 362         }
 363 }
 364
 365 static void detach_attrs(struct config_item * item)
 366 {
 367         struct dentry * dentry = dget(item->ci_dentry);
 368         struct configfs_dirent * parent_sd;
 369         struct configfs_dirent * sd, * tmp;
 370
 371         if (!dentry)
 372                 return;
 373
 374         pr_debug("configfs %s: dropping attrs for  dir\n",
 375                  dentry->d_name.name);
 376
 377         parent_sd = dentry->d_fsdata;
 378         list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
 379                 if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
 380                         continue;
 381                 list_del_init(&sd->s_sibling);
 382                 configfs_drop_dentry(sd, dentry);
 383                 configfs_put(sd);
 384         }
 385
 386         /**
 387          * Drop reference from dget() on entrance.
 388          */
 389         dput(dentry);
 390 }
 391
 392 static int populate_attrs(struct config_item *item)
 393 {
 394         struct config_item_type *t = item->ci_type;
 395         struct configfs_attribute *attr;
 396         int error = 0;
 397         int i;
 398
 399         if (!t)
 400                 return -EINVAL;
 401         if (t->ct_attrs) {
 402                 for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
 403                         if ((error = configfs_create_file(item, attr)))
 404                                 break;
 405                 }
 406         }
 407
 408         if (error)
 409                 detach_attrs(item);
 410
 411         return error;
 412 }
 413
 414 static int configfs_attach_group(struct config_item *parent_item,
 415                                  struct config_item *item,
 416                                  struct dentry *dentry);
 417 static void configfs_detach_group(struct config_item *item);
 418
 419 static void detach_groups(struct config_group *group)
 420 {
 421         struct dentry * dentry = dget(group->cg_item.ci_dentry);
 422         struct dentry *child;
 423         struct configfs_dirent *parent_sd;
 424         struct configfs_dirent *sd, *tmp;
 425
 426         if (!dentry)
 427                 return;
 428
 429         parent_sd = dentry->d_fsdata;
 430         list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
 431                 if (!sd->s_element ||
 432                     !(sd->s_type & CONFIGFS_USET_DEFAULT))
 433                         continue;
 434
 435                 child = sd->s_dentry;
 436
 437                 configfs_detach_group(sd->s_element);
 438                 child->d_inode->i_flags |= S_DEAD;
 439
 440                 /*
 441                  * From rmdir/unregister, a configfs_detach_prep() pass
 442                  * has taken our i_mutex for us.  Drop it.
 443                  * From mkdir/register cleanup, there is no sem held.
 444                  */
 445                 if (sd->s_type & CONFIGFS_USET_DROPPING)
 446                         mutex_unlock(&child->d_inode->i_mutex);
 447
 448                 d_delete(child);
 449                 dput(child);
 450         }
 451
 452         /**
 453          * Drop reference from dget() on entrance.
 454          */
 455         dput(dentry);
 456 }
 457
 458 /*
 459  * This fakes mkdir(2) on a default_groups[] entry.  It
 460  * creates a dentry, attachs it, and then does fixup
 461  * on the sd->s_type.
 462  *
 463  * We could, perhaps, tweak our parent's ->mkdir for a minute and
 464  * try using vfs_mkdir.  Just a thought.
 465  */
 466 static int create_default_group(struct config_group *parent_group,
 467                                 struct config_group *group)
 468 {
 469         int ret;
 470         struct qstr name;
 471         struct configfs_dirent *sd;
 472         /* We trust the caller holds a reference to parent */
 473         struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
 474
 475         if (!group->cg_item.ci_name)
 476                 group->cg_item.ci_name = group->cg_item.ci_namebuf;
 477         name.name = group->cg_item.ci_name;
 478         name.len = strlen(name.name);
 479         name.hash = full_name_hash(name.name, name.len);
 480
 481         ret = -ENOMEM;
 482         child = d_alloc(parent, &name);
 483         if (child) {
 484                 d_add(child, NULL);
 485
 486                 ret = configfs_attach_group(&parent_group->cg_item,
 487                                             &group->cg_item, child);
 488                 if (!ret) {
 489                         sd = child->d_fsdata;
 490                         sd->s_type |= CONFIGFS_USET_DEFAULT;
 491                 } else {
 492                         d_delete(child);
 493                         dput(child);
 494                 }
 495         }
 496
 497         return ret;
 498 }
 499
 500 static int populate_groups(struct config_group *group)
 501 {
 502         struct config_group *new_group;
 503         struct dentry *dentry = group->cg_item.ci_dentry;
 504         int ret = 0;
 505         int i;
 506
 507         if (group && group->default_groups) {
 508                 /* FYI, we're faking mkdir here
 509                  * I'm not sure we need this semaphore, as we're called
 510                  * from our parent's mkdir.  That holds our parent's
 511                  * i_mutex, so afaik lookup cannot continue through our
 512                  * parent to find us, let alone mess with our tree.
 513                  * That said, taking our i_mutex is closer to mkdir
 514                  * emulation, and shouldn't hurt. */
 515                 mutex_lock(&dentry->d_inode->i_mutex);
 516
 517                 for (i = 0; group->default_groups[i]; i++) {
 518                         new_group = group->default_groups[i];
 519
 520                         ret = create_default_group(group, new_group);
 521                         if (ret)
 522                                 break;
 523                 }
 524
 525                 mutex_unlock(&dentry->d_inode->i_mutex);
 526         }
 527
 528         if (ret)
 529                 detach_groups(group);
 530
 531         return ret;
 532 }
 533
 534 /*
 535  * All of link_obj/unlink_obj/link_group/unlink_group require that
 536  * subsys->su_sem is held.
 537  */
 538
 539 static void unlink_obj(struct config_item *item)
 540 {
 541         struct config_group *group;
 542
 543         group = item->ci_group;
 544         if (group) {
 545                 list_del_init(&item->ci_entry);
 546
 547                 item->ci_group = NULL;
 548                 item->ci_parent = NULL;
 549                 config_item_put(item);
 550
 551                 config_group_put(group);
 552         }
 553 }
 554
 555 static void link_obj(struct config_item *parent_item, struct config_item *item)
 556 {
 557         /* Parent seems redundant with group, but it makes certain
 558          * traversals much nicer. */
 559         item->ci_parent = parent_item;
 560         item->ci_group = config_group_get(to_config_group(parent_item));
 561         list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
 562
 563         config_item_get(item);
 564 }
 565
 566 static void unlink_group(struct config_group *group)
 567 {
 568         int i;
 569         struct config_group *new_group;
 570
 571         if (group->default_groups) {
 572                 for (i = 0; group->default_groups[i]; i++) {
 573                         new_group = group->default_groups[i];
 574                         unlink_group(new_group);
 575                 }
 576         }
 577
 578         group->cg_subsys = NULL;
 579         unlink_obj(&group->cg_item);
 580 }
 581
 582 static void link_group(struct config_group *parent_group, struct config_group *group)
 583 {
 584         int i;
 585         struct config_group *new_group;
 586         struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
 587
 588         link_obj(&parent_group->cg_item, &group->cg_item);
 589
 590         if (parent_group->cg_subsys)
 591                 subsys = parent_group->cg_subsys;
 592         else if (configfs_is_root(&parent_group->cg_item))
 593                 subsys = to_configfs_subsystem(group);
 594         else
 595                 BUG();
 596         group->cg_subsys = subsys;
 597
 598         if (group->default_groups) {
 599                 for (i = 0; group->default_groups[i]; i++) {
 600                         new_group = group->default_groups[i];
 601                         link_group(group, new_group);
 602                 }
 603         }
 604 }
 605
 606 /*
 607  * The goal is that configfs_attach_item() (and
 608  * configfs_attach_group()) can be called from either the VFS or this
 609  * module.  That is, they assume that the items have been created,
 610  * the dentry allocated, and the dcache is all ready to go.
 611  *
 612  * If they fail, they must clean up after themselves as if they
 613  * had never been called.  The caller (VFS or local function) will
 614  * handle cleaning up the dcache bits.
 615  *
 616  * configfs_detach_group() and configfs_detach_item() behave similarly on
 617  * the way out.  They assume that the proper semaphores are held, they
 618  * clean up the configfs items, and they expect their callers will
 619  * handle the dcache bits.
 620  */
 621 static int configfs_attach_item(struct config_item *parent_item,
 622                                 struct config_item *item,
 623                                 struct dentry *dentry)
 624 {
 625         int ret;
 626
 627         ret = configfs_create_dir(item, dentry);
 628         if (!ret) {
 629                 ret = populate_attrs(item);
 630                 if (ret) {
 631                         configfs_remove_dir(item);
 632                         d_delete(dentry);
 633                 }
 634         }
 635
 636         return ret;
 637 }
 638
 639 static void configfs_detach_item(struct config_item *item)
 640 {
 641         detach_attrs(item);
 642         configfs_remove_dir(item);
 643 }
 644
 645 static int configfs_attach_group(struct config_item *parent_item,
 646                                  struct config_item *item,
 647                                  struct dentry *dentry)
 648 {
 649         int ret;
 650         struct configfs_dirent *sd;
 651
 652         ret = configfs_attach_item(parent_item, item, dentry);
 653         if (!ret) {
 654                 sd = dentry->d_fsdata;
 655                 sd->s_type |= CONFIGFS_USET_DIR;
 656
 657                 ret = populate_groups(to_config_group(item));
 658                 if (ret) {
 659                         configfs_detach_item(item);
 660                         d_delete(dentry);
 661                 }
 662         }
 663
 664         return ret;
 665 }
 666
 667 static void configfs_detach_group(struct config_item *item)
 668 {
 669         detach_groups(to_config_group(item));
 670         configfs_detach_item(item);
 671 }
 672
 673 /*
 674  * Drop the initial reference from make_item()/make_group()
 675  * This function assumes that reference is held on item
 676  * and that item holds a valid reference to the parent.  Also, it
 677  * assumes the caller has validated ci_type.
 678  */
 679 static void client_drop_item(struct config_item *parent_item,
 680                              struct config_item *item)
 681 {
 682         struct config_item_type *type;
 683
 684         type = parent_item->ci_type;
 685         BUG_ON(!type);
 686
 687         if (type->ct_group_ops && type->ct_group_ops->drop_item)
 688                 type->ct_group_ops->drop_item(to_config_group(parent_item),
 689                                                 item);
 690         else
 691                 config_item_put(item);
 692 }
 693
 694
 695 static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 696 {
 697         int ret;
 698         struct config_group *group;
 699         struct config_item *item;
 700         struct config_item *parent_item;
 701         struct configfs_subsystem *subsys;
 702         struct configfs_dirent *sd;
 703         struct config_item_type *type;
 704         struct module *owner;
 705         char *name;
 706
 707         if (dentry->d_parent == configfs_sb->s_root)
 708                 return -EPERM;
 709
 710         sd = dentry->d_parent->d_fsdata;
 711         if (!(sd->s_type & CONFIGFS_USET_DIR))
 712                 return -EPERM;
 713
 714         parent_item = configfs_get_config_item(dentry->d_parent);
 715         type = parent_item->ci_type;
 716         subsys = to_config_group(parent_item)->cg_subsys;
 717         BUG_ON(!subsys);
 718
 719         if (!type || !type->ct_group_ops ||
 720             (!type->ct_group_ops->make_group &&
 721              !type->ct_group_ops->make_item)) {
 722                 config_item_put(parent_item);
 723                 return -EPERM;  /* What lack-of-mkdir returns */
 724         }
 725
 726         name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
 727         if (!name) {
 728                 config_item_put(parent_item);
 729                 return -ENOMEM;
 730         }
 731         snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
 732
 733         down(&subsys->su_sem);
 734         group = NULL;
 735         item = NULL;
 736         if (type->ct_group_ops->make_group) {
 737                 group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
 738                 if (group) {
 739                         link_group(to_config_group(parent_item), group);
 740                         item = &group->cg_item;
 741                 }
 742         } else {
 743                 item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
 744                 if (item)
 745                         link_obj(parent_item, item);
 746         }
 747         up(&subsys->su_sem);
 748
 749         kfree(name);
 750         if (!item) {
 751                 config_item_put(parent_item);
 752                 return -ENOMEM;
 753         }
 754
 755         ret = -EINVAL;
 756         type = item->ci_type;
 757         if (type) {
 758                 owner = type->ct_owner;
 759                 if (try_module_get(owner)) {
 760                         if (group) {
 761                                 ret = configfs_attach_group(parent_item,
 762                                                             item,
 763                                                             dentry);
 764                         } else {
 765                                 ret = configfs_attach_item(parent_item,
 766                                                            item,
 767                                                            dentry);
 768                         }
 769
 770                         if (ret) {
 771                                 down(&subsys->su_sem);
 772                                 if (group)
 773                                         unlink_group(group);
 774                                 else
 775                                         unlink_obj(item);
 776                                 client_drop_item(parent_item, item);
 777                                 up(&subsys->su_sem);
 778
 779                                 config_item_put(parent_item);
 780                                 module_put(owner);
 781                         }
 782                 }
 783         }
 784
 785         return ret;
 786 }
 787
 788 static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
 789 {
 790         struct config_item *parent_item;
 791         struct config_item *item;
 792         struct configfs_subsystem *subsys;
 793         struct configfs_dirent *sd;
 794         struct module *owner = NULL;
 795         int ret;
 796
 797         if (dentry->d_parent == configfs_sb->s_root)
 798                 return -EPERM;
 799
 800         sd = dentry->d_fsdata;
 801         if (sd->s_type & CONFIGFS_USET_DEFAULT)
 802                 return -EPERM;
 803
 804         parent_item = configfs_get_config_item(dentry->d_parent);
 805         subsys = to_config_group(parent_item)->cg_subsys;
 806         BUG_ON(!subsys);
 807
 808         if (!parent_item->ci_type) {
 809                 config_item_put(parent_item);
 810                 return -EINVAL;
 811         }
 812
 813         ret = configfs_detach_prep(dentry);
 814         if (ret) {
 815                 configfs_detach_rollback(dentry);
 816                 config_item_put(parent_item);
 817                 return ret;
 818         }
 819
 820         item = configfs_get_config_item(dentry);
 821
 822         /* Drop reference from above, item already holds one. */
 823         config_item_put(parent_item);
 824
 825         if (item->ci_type)
 826                 owner = item->ci_type->ct_owner;
 827
 828         if (sd->s_type & CONFIGFS_USET_DIR) {
 829                 configfs_detach_group(item);
 830
 831                 down(&subsys->su_sem);
 832                 unlink_group(to_config_group(item));
 833         } else {
 834                 configfs_detach_item(item);
 835
 836                 down(&subsys->su_sem);
 837                 unlink_obj(item);
 838         }
 839
 840         client_drop_item(parent_item, item);
 841         up(&subsys->su_sem);
 842
 843         /* Drop our reference from above */
 844         config_item_put(item);
 845
 846         module_put(owner);
 847
 848         return 0;
 849 }
 850
 851 struct inode_operations configfs_dir_inode_operations = {
 852         .mkdir          = configfs_mkdir,
 853         .rmdir          = configfs_rmdir,
 854         .symlink        = configfs_symlink,
 855         .unlink         = configfs_unlink,
 856         .lookup         = configfs_lookup,
 857         .setattr        = configfs_setattr,
 858 };
 859
 860 #if 0
 861 int configfs_rename_dir(struct config_item * item, const char *new_name)
 862 {
 863         int error = 0;
 864         struct dentry * new_dentry, * parent;
 865
 866         if (!strcmp(config_item_name(item), new_name))
 867                 return -EINVAL;
 868
 869         if (!item->parent)
 870                 return -EINVAL;
 871
 872         down_write(&configfs_rename_sem);
 873         parent = item->parent->dentry;
 874
 875         mutex_lock(&parent->d_inode->i_mutex);
 876
 877         new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
 878         if (!IS_ERR(new_dentry)) {
 879                 if (!new_dentry->d_inode) {
 880                         error = config_item_set_name(item, "%s", new_name);
 881                         if (!error) {
 882                                 d_add(new_dentry, NULL);
 883                                 d_move(item->dentry, new_dentry);
 884                         }
 885                         else
 886                                 d_delete(new_dentry);
 887                 } else
 888                         error = -EEXIST;
 889                 dput(new_dentry);
 890         }
 891         mutex_unlock(&parent->d_inode->i_mutex);
 892         up_write(&configfs_rename_sem);
 893
 894         return error;
 895 }
 896 #endif
 897
 898 static int configfs_dir_open(struct inode *inode, struct file *file)
 899 {
 900         struct dentry * dentry = file->f_dentry;
 901         struct configfs_dirent * parent_sd = dentry->d_fsdata;
 902
 903         mutex_lock(&dentry->d_inode->i_mutex);
 904         file->private_data = configfs_new_dirent(parent_sd, NULL);
 905         mutex_unlock(&dentry->d_inode->i_mutex);
 906
 907         return file->private_data ? 0 : -ENOMEM;
 908
 909 }
 910
 911 static int configfs_dir_close(struct inode *inode, struct file *file)
 912 {
 913         struct dentry * dentry = file->f_dentry;
 914         struct configfs_dirent * cursor = file->private_data;
 915
 916         mutex_lock(&dentry->d_inode->i_mutex);
 917         list_del_init(&cursor->s_sibling);
 918         mutex_unlock(&dentry->d_inode->i_mutex);
 919
 920         release_configfs_dirent(cursor);
 921
 922         return 0;
 923 }
 924
 925 /* Relationship between s_mode and the DT_xxx types */
 926 static inline unsigned char dt_type(struct configfs_dirent *sd)
 927 {
 928         return (sd->s_mode >> 12) & 15;
 929 }
 930
 931 static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
 932 {
 933         struct dentry *dentry = filp->f_dentry;
 934         struct configfs_dirent * parent_sd = dentry->d_fsdata;
 935         struct configfs_dirent *cursor = filp->private_data;
 936         struct list_head *p, *q = &cursor->s_sibling;
 937         ino_t ino;
 938         int i = filp->f_pos;
 939
 940         switch (i) {
 941                 case 0:
 942                         ino = dentry->d_inode->i_ino;
 943                         if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
 944                                 break;
 945                         filp->f_pos++;
 946                         i++;
 947                         /* fallthrough */
 948                 case 1:
 949                         ino = parent_ino(dentry);
 950                         if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
 951                                 break;
 952                         filp->f_pos++;
 953                         i++;
 954                         /* fallthrough */
 955                 default:
 956                         if (filp->f_pos == 2) {
 957                                 list_del(q);
 958                                 list_add(q, &parent_sd->s_children);
 959                         }
 960                         for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
 961                                 struct configfs_dirent *next;
 962                                 const char * name;
 963                                 int len;
 964
 965                                 next = list_entry(p, struct configfs_dirent,
 966                                                    s_sibling);
 967                                 if (!next->s_element)
 968                                         continue;
 969
 970                                 name = configfs_get_name(next);
 971                                 len = strlen(name);
 972                                 if (next->s_dentry)
 973                                         ino = next->s_dentry->d_inode->i_ino;
 974                                 else
 975                                         ino = iunique(configfs_sb, 2);
 976
 977                                 if (filldir(dirent, name, len, filp->f_pos, ino,
 978                                                  dt_type(next)) < 0)
 979                                         return 0;
 980
 981                                 list_del(q);
 982                                 list_add(q, p);
 983                                 p = q;
 984                                 filp->f_pos++;
 985                         }
 986         }
 987         return 0;
 988 }
 989
 990 static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin)
 991 {
 992         struct dentry * dentry = file->f_dentry;
 993
 994         mutex_lock(&dentry->d_inode->i_mutex);
 995         switch (origin) {
 996                 case 1:
 997                         offset += file->f_pos;
 998                 case 0:
 999                         if (offset >= 0)
1000                                 break;
1001                 default:
1002                         mutex_unlock(&file->f_dentry->d_inode->i_mutex);
1003                         return -EINVAL;
1004         }
1005         if (offset != file->f_pos) {
1006                 file->f_pos = offset;
1007                 if (file->f_pos >= 2) {
1008                         struct configfs_dirent *sd = dentry->d_fsdata;
1009                         struct configfs_dirent *cursor = file->private_data;
1010                         struct list_head *p;
1011                         loff_t n = file->f_pos - 2;
1012
1013                         list_del(&cursor->s_sibling);
1014                         p = sd->s_children.next;
1015                         while (n && p != &sd->s_children) {
1016                                 struct configfs_dirent *next;
1017                                 next = list_entry(p, struct configfs_dirent,
1018                                                    s_sibling);
1019                                 if (next->s_element)
1020                                         n--;
1021                                 p = p->next;
1022                         }
1023                         list_add_tail(&cursor->s_sibling, p);
1024                 }
1025         }
1026         mutex_unlock(&dentry->d_inode->i_mutex);
1027         return offset;
1028 }
1029
1030 struct file_operations configfs_dir_operations = {
1031         .open           = configfs_dir_open,
1032         .release        = configfs_dir_close,
1033         .llseek         = configfs_dir_lseek,
1034         .read           = generic_read_dir,
1035         .readdir        = configfs_readdir,
1036 };
1037
1038 int configfs_register_subsystem(struct configfs_subsystem *subsys)
1039 {
1040         int err;
1041         struct config_group *group = &subsys->su_group;
1042         struct qstr name;
1043         struct dentry *dentry;
1044         struct configfs_dirent *sd;
1045
1046         err = configfs_pin_fs();
1047         if (err)
1048                 return err;
1049
1050         if (!group->cg_item.ci_name)
1051                 group->cg_item.ci_name = group->cg_item.ci_namebuf;
1052
1053         sd = configfs_sb->s_root->d_fsdata;
1054         link_group(to_config_group(sd->s_element), group);
1055
1056         mutex_lock(&configfs_sb->s_root->d_inode->i_mutex);
1057
1058         name.name = group->cg_item.ci_name;
1059         name.len = strlen(name.name);
1060         name.hash = full_name_hash(name.name, name.len);
1061
1062         err = -ENOMEM;
1063         dentry = d_alloc(configfs_sb->s_root, &name);
1064         if (!dentry)
1065                 goto out_release;
1066
1067         d_add(dentry, NULL);
1068
1069         err = configfs_attach_group(sd->s_element, &group->cg_item,
1070                                     dentry);
1071         if (!err)
1072                 dentry = NULL;
1073         else
1074                 d_delete(dentry);
1075
1076         mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1077
1078         if (dentry) {
1079             dput(dentry);
1080 out_release:
1081             unlink_group(group);
1082             configfs_release_fs();
1083         }
1084
1085         return err;
1086 }
1087
1088 void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
1089 {
1090         struct config_group *group = &subsys->su_group;
1091         struct dentry *dentry = group->cg_item.ci_dentry;
1092
1093         if (dentry->d_parent != configfs_sb->s_root) {
1094                 printk(KERN_ERR "configfs: Tried to unregister non-subsystem!\n");
1095                 return;
1096         }
1097
1098         mutex_lock(&configfs_sb->s_root->d_inode->i_mutex);
1099         mutex_lock(&dentry->d_inode->i_mutex);
1100         if (configfs_detach_prep(dentry)) {
1101                 printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n");
1102         }
1103         configfs_detach_group(&group->cg_item);
1104         dentry->d_inode->i_flags |= S_DEAD;
1105         mutex_unlock(&dentry->d_inode->i_mutex);
1106
1107         d_delete(dentry);
1108
1109         mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1110
1111         dput(dentry);
1112
1113         unlink_group(group);
1114         configfs_release_fs();
1115 }
1116
1117 EXPORT_SYMBOL(configfs_register_subsystem);
1118 EXPORT_SYMBOL(configfs_unregister_subsystem);