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