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 /*
  90  *
  91  * Return -EEXIST if there is already a configfs element with the same
  92  * name for the same parent.
  93  *
  94  * called with parent inode's i_mutex held
  95  */
  96 int configfs_dirent_exists(struct configfs_dirent *parent_sd,
  97                            const unsigned char *new)
  98 {
  99         struct configfs_dirent * sd;
 100
 101         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 102                 if (sd->s_element) {
 103                         const unsigned char *existing = configfs_get_name(sd);
 104                         if (strcmp(existing, new))
 105                                 continue;
 106                         else
 107                                 return -EEXIST;
 108                 }
 109         }
 110
 111         return 0;
 112 }
 113
 114
 115 int configfs_make_dirent(struct configfs_dirent * parent_sd,
 116                          struct dentry * dentry, void * element,
 117                          umode_t mode, int type)
 118 {
 119         struct configfs_dirent * sd;
 120
 121         sd = configfs_new_dirent(parent_sd, element);
 122         if (!sd)
 123                 return -ENOMEM;
 124
 125         sd->s_mode = mode;
 126         sd->s_type = type;
 127         sd->s_dentry = dentry;
 128         if (dentry) {
 129                 dentry->d_fsdata = configfs_get(sd);
 130                 dentry->d_op = &configfs_dentry_ops;
 131         }
 132
 133         return 0;
 134 }
 135
 136 static int init_dir(struct inode * inode)
 137 {
 138         inode->i_op = &configfs_dir_inode_operations;
 139         inode->i_fop = &configfs_dir_operations;
 140
 141         /* directory inodes start off with i_nlink == 2 (for "." entry) */
 142         inode->i_nlink++;
 143         return 0;
 144 }
 145
 146 static int init_file(struct inode * inode)
 147 {
 148         inode->i_size = PAGE_SIZE;
 149         inode->i_fop = &configfs_file_operations;
 150         return 0;
 151 }
 152
 153 static int init_symlink(struct inode * inode)
 154 {
 155         inode->i_op = &configfs_symlink_inode_operations;
 156         return 0;
 157 }
 158
 159 static int create_dir(struct config_item * k, struct dentry * p,
 160                       struct dentry * d)
 161 {
 162         int error;
 163         umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
 164
 165         error = configfs_dirent_exists(p->d_fsdata, d->d_name.name);
 166         if (!error)
 167                 error = configfs_make_dirent(p->d_fsdata, d, k, mode,
 168                                              CONFIGFS_DIR);
 169         if (!error) {
 170                 error = configfs_create(d, mode, init_dir);
 171                 if (!error) {
 172                         p->d_inode->i_nlink++;
 173                         (d)->d_op = &configfs_dentry_ops;
 174                 } else {
 175                         struct configfs_dirent *sd = d->d_fsdata;
 176                         if (sd) {
 177                                 list_del_init(&sd->s_sibling);
 178                                 configfs_put(sd);
 179                         }
 180                 }
 181         }
 182         return error;
 183 }
 184
 185
 186 /**
 187  *      configfs_create_dir - create a directory for an config_item.
 188  *      @item:          config_itemwe're creating directory for.
 189  *      @dentry:        config_item's dentry.
 190  */
 191
 192 static int configfs_create_dir(struct config_item * item, struct dentry *dentry)
 193 {
 194         struct dentry * parent;
 195         int error = 0;
 196
 197         BUG_ON(!item);
 198
 199         if (item->ci_parent)
 200                 parent = item->ci_parent->ci_dentry;
 201         else if (configfs_mount && configfs_mount->mnt_sb)
 202                 parent = configfs_mount->mnt_sb->s_root;
 203         else
 204                 return -EFAULT;
 205
 206         error = create_dir(item,parent,dentry);
 207         if (!error)
 208                 item->ci_dentry = dentry;
 209         return error;
 210 }
 211
 212 int configfs_create_link(struct configfs_symlink *sl,
 213                          struct dentry *parent,
 214                          struct dentry *dentry)
 215 {
 216         int err = 0;
 217         umode_t mode = S_IFLNK | S_IRWXUGO;
 218
 219         err = configfs_make_dirent(parent->d_fsdata, dentry, sl, mode,
 220                                    CONFIGFS_ITEM_LINK);
 221         if (!err) {
 222                 err = configfs_create(dentry, mode, init_symlink);
 223                 if (!err)
 224                         dentry->d_op = &configfs_dentry_ops;
 225                 else {
 226                         struct configfs_dirent *sd = dentry->d_fsdata;
 227                         if (sd) {
 228                                 list_del_init(&sd->s_sibling);
 229                                 configfs_put(sd);
 230                         }
 231                 }
 232         }
 233         return err;
 234 }
 235
 236 static void remove_dir(struct dentry * d)
 237 {
 238         struct dentry * parent = dget(d->d_parent);
 239         struct configfs_dirent * sd;
 240
 241         sd = d->d_fsdata;
 242         list_del_init(&sd->s_sibling);
 243         configfs_put(sd);
 244         if (d->d_inode)
 245                 simple_rmdir(parent->d_inode,d);
 246
 247         pr_debug(" o %s removing done (%d)\n",d->d_name.name,
 248                  atomic_read(&d->d_count));
 249
 250         dput(parent);
 251 }
 252
 253 /**
 254  * configfs_remove_dir - remove an config_item's directory.
 255  * @item:       config_item we're removing.
 256  *
 257  * The only thing special about this is that we remove any files in
 258  * the directory before we remove the directory, and we've inlined
 259  * what used to be configfs_rmdir() below, instead of calling separately.
 260  */
 261
 262 static void configfs_remove_dir(struct config_item * item)
 263 {
 264         struct dentry * dentry = dget(item->ci_dentry);
 265
 266         if (!dentry)
 267                 return;
 268
 269         remove_dir(dentry);
 270         /**
 271          * Drop reference from dget() on entrance.
 272          */
 273         dput(dentry);
 274 }
 275
 276
 277 /* attaches attribute's configfs_dirent to the dentry corresponding to the
 278  * attribute file
 279  */
 280 static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
 281 {
 282         struct configfs_attribute * attr = sd->s_element;
 283         int error;
 284
 285         dentry->d_fsdata = configfs_get(sd);
 286         sd->s_dentry = dentry;
 287         error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG, init_file);
 288         if (error) {
 289                 configfs_put(sd);
 290                 return error;
 291         }
 292
 293         dentry->d_op = &configfs_dentry_ops;
 294         d_rehash(dentry);
 295
 296         return 0;
 297 }
 298
 299 static struct dentry * configfs_lookup(struct inode *dir,
 300                                        struct dentry *dentry,
 301                                        struct nameidata *nd)
 302 {
 303         struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
 304         struct configfs_dirent * sd;
 305         int found = 0;
 306         int err = 0;
 307
 308         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 309                 if (sd->s_type & CONFIGFS_NOT_PINNED) {
 310                         const unsigned char * name = configfs_get_name(sd);
 311
 312                         if (strcmp(name, dentry->d_name.name))
 313                                 continue;
 314
 315                         found = 1;
 316                         err = configfs_attach_attr(sd, dentry);
 317                         break;
 318                 }
 319         }
 320
 321         if (!found) {
 322                 /*
 323                  * If it doesn't exist and it isn't a NOT_PINNED item,
 324                  * it must be negative.
 325                  */
 326                 return simple_lookup(dir, dentry, nd);
 327         }
 328
 329         return ERR_PTR(err);
 330 }
 331
 332 /*
 333  * Only subdirectories count here.  Files (CONFIGFS_NOT_PINNED) are
 334  * attributes and are removed by rmdir().  We recurse, taking i_mutex
 335  * on all children that are candidates for default detach.  If the
 336  * result is clean, then configfs_detach_group() will handle dropping
 337  * i_mutex.  If there is an error, the caller will clean up the i_mutex
 338  * holders via configfs_detach_rollback().
 339  */
 340 static int configfs_detach_prep(struct dentry *dentry)
 341 {
 342         struct configfs_dirent *parent_sd = dentry->d_fsdata;
 343         struct configfs_dirent *sd;
 344         int ret;
 345
 346         ret = -EBUSY;
 347         if (!list_empty(&parent_sd->s_links))
 348                 goto out;
 349
 350         ret = 0;
 351         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 352                 if (sd->s_type & CONFIGFS_NOT_PINNED)
 353                         continue;
 354                 if (sd->s_type & CONFIGFS_USET_DEFAULT) {
 355                         mutex_lock(&sd->s_dentry->d_inode->i_mutex);
 356                         /* Mark that we've taken i_mutex */
 357                         sd->s_type |= CONFIGFS_USET_DROPPING;
 358
 359                         ret = configfs_detach_prep(sd->s_dentry);
 360                         if (!ret)
 361                                 continue;
 362                 } else
 363                         ret = -ENOTEMPTY;
 364
 365                 break;
 366         }
 367
 368 out:
 369         return ret;
 370 }
 371
 372 /*
 373  * Walk the tree, dropping i_mutex wherever CONFIGFS_USET_DROPPING is
 374  * set.
 375  */
 376 static void configfs_detach_rollback(struct dentry *dentry)
 377 {
 378         struct configfs_dirent *parent_sd = dentry->d_fsdata;
 379         struct configfs_dirent *sd;
 380
 381         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 382                 if (sd->s_type & CONFIGFS_USET_DEFAULT) {
 383                         configfs_detach_rollback(sd->s_dentry);
 384
 385                         if (sd->s_type & CONFIGFS_USET_DROPPING) {
 386                                 sd->s_type &= ~CONFIGFS_USET_DROPPING;
 387                                 mutex_unlock(&sd->s_dentry->d_inode->i_mutex);
 388                         }
 389                 }
 390         }
 391 }
 392
 393 static void detach_attrs(struct config_item * item)
 394 {
 395         struct dentry * dentry = dget(item->ci_dentry);
 396         struct configfs_dirent * parent_sd;
 397         struct configfs_dirent * sd, * tmp;
 398
 399         if (!dentry)
 400                 return;
 401
 402         pr_debug("configfs %s: dropping attrs for  dir\n",
 403                  dentry->d_name.name);
 404
 405         parent_sd = dentry->d_fsdata;
 406         list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
 407                 if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
 408                         continue;
 409                 list_del_init(&sd->s_sibling);
 410                 configfs_drop_dentry(sd, dentry);
 411                 configfs_put(sd);
 412         }
 413
 414         /**
 415          * Drop reference from dget() on entrance.
 416          */
 417         dput(dentry);
 418 }
 419
 420 static int populate_attrs(struct config_item *item)
 421 {
 422         struct config_item_type *t = item->ci_type;
 423         struct configfs_attribute *attr;
 424         int error = 0;
 425         int i;
 426
 427         if (!t)
 428                 return -EINVAL;
 429         if (t->ct_attrs) {
 430                 for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
 431                         if ((error = configfs_create_file(item, attr)))
 432                                 break;
 433                 }
 434         }
 435
 436         if (error)
 437                 detach_attrs(item);
 438
 439         return error;
 440 }
 441
 442 static int configfs_attach_group(struct config_item *parent_item,
 443                                  struct config_item *item,
 444                                  struct dentry *dentry);
 445 static void configfs_detach_group(struct config_item *item);
 446
 447 static void detach_groups(struct config_group *group)
 448 {
 449         struct dentry * dentry = dget(group->cg_item.ci_dentry);
 450         struct dentry *child;
 451         struct configfs_dirent *parent_sd;
 452         struct configfs_dirent *sd, *tmp;
 453
 454         if (!dentry)
 455                 return;
 456
 457         parent_sd = dentry->d_fsdata;
 458         list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
 459                 if (!sd->s_element ||
 460                     !(sd->s_type & CONFIGFS_USET_DEFAULT))
 461                         continue;
 462
 463                 child = sd->s_dentry;
 464
 465                 configfs_detach_group(sd->s_element);
 466                 child->d_inode->i_flags |= S_DEAD;
 467
 468                 /*
 469                  * From rmdir/unregister, a configfs_detach_prep() pass
 470                  * has taken our i_mutex for us.  Drop it.
 471                  * From mkdir/register cleanup, there is no sem held.
 472                  */
 473                 if (sd->s_type & CONFIGFS_USET_DROPPING)
 474                         mutex_unlock(&child->d_inode->i_mutex);
 475
 476                 d_delete(child);
 477                 dput(child);
 478         }
 479
 480         /**
 481          * Drop reference from dget() on entrance.
 482          */
 483         dput(dentry);
 484 }
 485
 486 /*
 487  * This fakes mkdir(2) on a default_groups[] entry.  It
 488  * creates a dentry, attachs it, and then does fixup
 489  * on the sd->s_type.
 490  *
 491  * We could, perhaps, tweak our parent's ->mkdir for a minute and
 492  * try using vfs_mkdir.  Just a thought.
 493  */
 494 static int create_default_group(struct config_group *parent_group,
 495                                 struct config_group *group)
 496 {
 497         int ret;
 498         struct qstr name;
 499         struct configfs_dirent *sd;
 500         /* We trust the caller holds a reference to parent */
 501         struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
 502
 503         if (!group->cg_item.ci_name)
 504                 group->cg_item.ci_name = group->cg_item.ci_namebuf;
 505         name.name = group->cg_item.ci_name;
 506         name.len = strlen(name.name);
 507         name.hash = full_name_hash(name.name, name.len);
 508
 509         ret = -ENOMEM;
 510         child = d_alloc(parent, &name);
 511         if (child) {
 512                 d_add(child, NULL);
 513
 514                 ret = configfs_attach_group(&parent_group->cg_item,
 515                                             &group->cg_item, child);
 516                 if (!ret) {
 517                         sd = child->d_fsdata;
 518                         sd->s_type |= CONFIGFS_USET_DEFAULT;
 519                 } else {
 520                         d_delete(child);
 521                         dput(child);
 522                 }
 523         }
 524
 525         return ret;
 526 }
 527
 528 static int populate_groups(struct config_group *group)
 529 {
 530         struct config_group *new_group;
 531         struct dentry *dentry = group->cg_item.ci_dentry;
 532         int ret = 0;
 533         int i;
 534
 535         if (group->default_groups) {
 536                 /*
 537                  * FYI, we're faking mkdir here
 538                  * I'm not sure we need this semaphore, as we're called
 539                  * from our parent's mkdir.  That holds our parent's
 540                  * i_mutex, so afaik lookup cannot continue through our
 541                  * parent to find us, let alone mess with our tree.
 542                  * That said, taking our i_mutex is closer to mkdir
 543                  * emulation, and shouldn't hurt.
 544                  */
 545                 mutex_lock(&dentry->d_inode->i_mutex);
 546
 547                 for (i = 0; group->default_groups[i]; i++) {
 548                         new_group = group->default_groups[i];
 549
 550                         ret = create_default_group(group, new_group);
 551                         if (ret)
 552                                 break;
 553                 }
 554
 555                 mutex_unlock(&dentry->d_inode->i_mutex);
 556         }
 557
 558         if (ret)
 559                 detach_groups(group);
 560
 561         return ret;
 562 }
 563
 564 /*
 565  * All of link_obj/unlink_obj/link_group/unlink_group require that
 566  * subsys->su_sem is held.
 567  */
 568
 569 static void unlink_obj(struct config_item *item)
 570 {
 571         struct config_group *group;
 572
 573         group = item->ci_group;
 574         if (group) {
 575                 list_del_init(&item->ci_entry);
 576
 577                 item->ci_group = NULL;
 578                 item->ci_parent = NULL;
 579
 580                 /* Drop the reference for ci_entry */
 581                 config_item_put(item);
 582
 583                 /* Drop the reference for ci_parent */
 584                 config_group_put(group);
 585         }
 586 }
 587
 588 static void link_obj(struct config_item *parent_item, struct config_item *item)
 589 {
 590         /*
 591          * Parent seems redundant with group, but it makes certain
 592          * traversals much nicer.
 593          */
 594         item->ci_parent = parent_item;
 595
 596         /*
 597          * We hold a reference on the parent for the child's ci_parent
 598          * link.
 599          */
 600         item->ci_group = config_group_get(to_config_group(parent_item));
 601         list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
 602
 603         /*
 604          * We hold a reference on the child for ci_entry on the parent's
 605          * cg_children
 606          */
 607         config_item_get(item);
 608 }
 609
 610 static void unlink_group(struct config_group *group)
 611 {
 612         int i;
 613         struct config_group *new_group;
 614
 615         if (group->default_groups) {
 616                 for (i = 0; group->default_groups[i]; i++) {
 617                         new_group = group->default_groups[i];
 618                         unlink_group(new_group);
 619                 }
 620         }
 621
 622         group->cg_subsys = NULL;
 623         unlink_obj(&group->cg_item);
 624 }
 625
 626 static void link_group(struct config_group *parent_group, struct config_group *group)
 627 {
 628         int i;
 629         struct config_group *new_group;
 630         struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
 631
 632         link_obj(&parent_group->cg_item, &group->cg_item);
 633
 634         if (parent_group->cg_subsys)
 635                 subsys = parent_group->cg_subsys;
 636         else if (configfs_is_root(&parent_group->cg_item))
 637                 subsys = to_configfs_subsystem(group);
 638         else
 639                 BUG();
 640         group->cg_subsys = subsys;
 641
 642         if (group->default_groups) {
 643                 for (i = 0; group->default_groups[i]; i++) {
 644                         new_group = group->default_groups[i];
 645                         link_group(group, new_group);
 646                 }
 647         }
 648 }
 649
 650 /*
 651  * The goal is that configfs_attach_item() (and
 652  * configfs_attach_group()) can be called from either the VFS or this
 653  * module.  That is, they assume that the items have been created,
 654  * the dentry allocated, and the dcache is all ready to go.
 655  *
 656  * If they fail, they must clean up after themselves as if they
 657  * had never been called.  The caller (VFS or local function) will
 658  * handle cleaning up the dcache bits.
 659  *
 660  * configfs_detach_group() and configfs_detach_item() behave similarly on
 661  * the way out.  They assume that the proper semaphores are held, they
 662  * clean up the configfs items, and they expect their callers will
 663  * handle the dcache bits.
 664  */
 665 static int configfs_attach_item(struct config_item *parent_item,
 666                                 struct config_item *item,
 667                                 struct dentry *dentry)
 668 {
 669         int ret;
 670
 671         ret = configfs_create_dir(item, dentry);
 672         if (!ret) {
 673                 ret = populate_attrs(item);
 674                 if (ret) {
 675                         configfs_remove_dir(item);
 676                         d_delete(dentry);
 677                 }
 678         }
 679
 680         return ret;
 681 }
 682
 683 static void configfs_detach_item(struct config_item *item)
 684 {
 685         detach_attrs(item);
 686         configfs_remove_dir(item);
 687 }
 688
 689 static int configfs_attach_group(struct config_item *parent_item,
 690                                  struct config_item *item,
 691                                  struct dentry *dentry)
 692 {
 693         int ret;
 694         struct configfs_dirent *sd;
 695
 696         ret = configfs_attach_item(parent_item, item, dentry);
 697         if (!ret) {
 698                 sd = dentry->d_fsdata;
 699                 sd->s_type |= CONFIGFS_USET_DIR;
 700
 701                 ret = populate_groups(to_config_group(item));
 702                 if (ret) {
 703                         configfs_detach_item(item);
 704                         d_delete(dentry);
 705                 }
 706         }
 707
 708         return ret;
 709 }
 710
 711 static void configfs_detach_group(struct config_item *item)
 712 {
 713         detach_groups(to_config_group(item));
 714         configfs_detach_item(item);
 715 }
 716
 717 /*
 718  * Drop the initial reference from make_item()/make_group()
 719  * This function assumes that reference is held on item
 720  * and that item holds a valid reference to the parent.  Also, it
 721  * assumes the caller has validated ci_type.
 722  */
 723 static void client_drop_item(struct config_item *parent_item,
 724                              struct config_item *item)
 725 {
 726         struct config_item_type *type;
 727
 728         type = parent_item->ci_type;
 729         BUG_ON(!type);
 730
 731         /*
 732          * If ->drop_item() exists, it is responsible for the
 733          * config_item_put().
 734          */
 735         if (type->ct_group_ops && type->ct_group_ops->drop_item)
 736                 type->ct_group_ops->drop_item(to_config_group(parent_item),
 737                                                 item);
 738         else
 739                 config_item_put(item);
 740 }
 741
 742
 743 static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 744 {
 745         int ret, module_got = 0;
 746         struct config_group *group;
 747         struct config_item *item;
 748         struct config_item *parent_item;
 749         struct configfs_subsystem *subsys;
 750         struct configfs_dirent *sd;
 751         struct config_item_type *type;
 752         struct module *owner = NULL;
 753         char *name;
 754
 755         if (dentry->d_parent == configfs_sb->s_root) {
 756                 ret = -EPERM;
 757                 goto out;
 758         }
 759
 760         sd = dentry->d_parent->d_fsdata;
 761         if (!(sd->s_type & CONFIGFS_USET_DIR)) {
 762                 ret = -EPERM;
 763                 goto out;
 764         }
 765
 766         /* Get a working ref for the duration of this function */
 767         parent_item = configfs_get_config_item(dentry->d_parent);
 768         type = parent_item->ci_type;
 769         subsys = to_config_group(parent_item)->cg_subsys;
 770         BUG_ON(!subsys);
 771
 772         if (!type || !type->ct_group_ops ||
 773             (!type->ct_group_ops->make_group &&
 774              !type->ct_group_ops->make_item)) {
 775                 ret = -EPERM;  /* Lack-of-mkdir returns -EPERM */
 776                 goto out_put;
 777         }
 778
 779         name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
 780         if (!name) {
 781                 ret = -ENOMEM;
 782                 goto out_put;
 783         }
 784
 785         snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
 786
 787         down(&subsys->su_sem);
 788         group = NULL;
 789         item = NULL;
 790         if (type->ct_group_ops->make_group) {
 791                 group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
 792                 if (group) {
 793                         link_group(to_config_group(parent_item), group);
 794                         item = &group->cg_item;
 795                 }
 796         } else {
 797                 item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
 798                 if (item)
 799                         link_obj(parent_item, item);
 800         }
 801         up(&subsys->su_sem);
 802
 803         kfree(name);
 804         if (!item) {
 805                 /*
 806                  * If item == NULL, then link_obj() was never called.
 807                  * There are no extra references to clean up.
 808                  */
 809                 ret = -ENOMEM;
 810                 goto out_put;
 811         }
 812
 813         /*
 814          * link_obj() has been called (via link_group() for groups).
 815          * From here on out, errors must clean that up.
 816          */
 817
 818         type = item->ci_type;
 819         if (!type) {
 820                 ret = -EINVAL;
 821                 goto out_unlink;
 822         }
 823
 824         owner = type->ct_owner;
 825         if (!try_module_get(owner)) {
 826                 ret = -EINVAL;
 827                 goto out_unlink;
 828         }
 829
 830         /*
 831          * I hate doing it this way, but if there is
 832          * an error,  module_put() probably should
 833          * happen after any cleanup.
 834          */
 835         module_got = 1;
 836
 837         if (group)
 838                 ret = configfs_attach_group(parent_item, item, dentry);
 839         else
 840                 ret = configfs_attach_item(parent_item, item, dentry);
 841
 842 out_unlink:
 843         if (ret) {
 844                 /* Tear down everything we built up */
 845                 down(&subsys->su_sem);
 846                 if (group)
 847                         unlink_group(group);
 848                 else
 849                         unlink_obj(item);
 850                 client_drop_item(parent_item, item);
 851                 up(&subsys->su_sem);
 852
 853                 if (module_got)
 854                         module_put(owner);
 855         }
 856
 857 out_put:
 858         /*
 859          * link_obj()/link_group() took a reference from child->parent,
 860          * so the parent is safely pinned.  We can drop our working
 861          * reference.
 862          */
 863         config_item_put(parent_item);
 864
 865 out:
 866         return ret;
 867 }
 868
 869 static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
 870 {
 871         struct config_item *parent_item;
 872         struct config_item *item;
 873         struct configfs_subsystem *subsys;
 874         struct configfs_dirent *sd;
 875         struct module *owner = NULL;
 876         int ret;
 877
 878         if (dentry->d_parent == configfs_sb->s_root)
 879                 return -EPERM;
 880
 881         sd = dentry->d_fsdata;
 882         if (sd->s_type & CONFIGFS_USET_DEFAULT)
 883                 return -EPERM;
 884
 885         /* Get a working ref until we have the child */
 886         parent_item = configfs_get_config_item(dentry->d_parent);
 887         subsys = to_config_group(parent_item)->cg_subsys;
 888         BUG_ON(!subsys);
 889
 890         if (!parent_item->ci_type) {
 891                 config_item_put(parent_item);
 892                 return -EINVAL;
 893         }
 894
 895         ret = configfs_detach_prep(dentry);
 896         if (ret) {
 897                 configfs_detach_rollback(dentry);
 898                 config_item_put(parent_item);
 899                 return ret;
 900         }
 901
 902         /* Get a working ref for the duration of this function */
 903         item = configfs_get_config_item(dentry);
 904
 905         /* Drop reference from above, item already holds one. */
 906         config_item_put(parent_item);
 907
 908         if (item->ci_type)
 909                 owner = item->ci_type->ct_owner;
 910
 911         if (sd->s_type & CONFIGFS_USET_DIR) {
 912                 configfs_detach_group(item);
 913
 914                 down(&subsys->su_sem);
 915                 unlink_group(to_config_group(item));
 916         } else {
 917                 configfs_detach_item(item);
 918
 919                 down(&subsys->su_sem);
 920                 unlink_obj(item);
 921         }
 922
 923         client_drop_item(parent_item, item);
 924         up(&subsys->su_sem);
 925
 926         /* Drop our reference from above */
 927         config_item_put(item);
 928
 929         module_put(owner);
 930
 931         return 0;
 932 }
 933
 934 struct inode_operations configfs_dir_inode_operations = {
 935         .mkdir          = configfs_mkdir,
 936         .rmdir          = configfs_rmdir,
 937         .symlink        = configfs_symlink,
 938         .unlink         = configfs_unlink,
 939         .lookup         = configfs_lookup,
 940         .setattr        = configfs_setattr,
 941 };
 942
 943 #if 0
 944 int configfs_rename_dir(struct config_item * item, const char *new_name)
 945 {
 946         int error = 0;
 947         struct dentry * new_dentry, * parent;
 948
 949         if (!strcmp(config_item_name(item), new_name))
 950                 return -EINVAL;
 951
 952         if (!item->parent)
 953                 return -EINVAL;
 954
 955         down_write(&configfs_rename_sem);
 956         parent = item->parent->dentry;
 957
 958         mutex_lock(&parent->d_inode->i_mutex);
 959
 960         new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
 961         if (!IS_ERR(new_dentry)) {
 962                 if (!new_dentry->d_inode) {
 963                         error = config_item_set_name(item, "%s", new_name);
 964                         if (!error) {
 965                                 d_add(new_dentry, NULL);
 966                                 d_move(item->dentry, new_dentry);
 967                         }
 968                         else
 969                                 d_delete(new_dentry);
 970                 } else
 971                         error = -EEXIST;
 972                 dput(new_dentry);
 973         }
 974         mutex_unlock(&parent->d_inode->i_mutex);
 975         up_write(&configfs_rename_sem);
 976
 977         return error;
 978 }
 979 #endif
 980
 981 static int configfs_dir_open(struct inode *inode, struct file *file)
 982 {
 983         struct dentry * dentry = file->f_dentry;
 984         struct configfs_dirent * parent_sd = dentry->d_fsdata;
 985
 986         mutex_lock(&dentry->d_inode->i_mutex);
 987         file->private_data = configfs_new_dirent(parent_sd, NULL);
 988         mutex_unlock(&dentry->d_inode->i_mutex);
 989
 990         return file->private_data ? 0 : -ENOMEM;
 991
 992 }
 993
 994 static int configfs_dir_close(struct inode *inode, struct file *file)
 995 {
 996         struct dentry * dentry = file->f_dentry;
 997         struct configfs_dirent * cursor = file->private_data;
 998
 999         mutex_lock(&dentry->d_inode->i_mutex);
1000         list_del_init(&cursor->s_sibling);
1001         mutex_unlock(&dentry->d_inode->i_mutex);
1002
1003         release_configfs_dirent(cursor);
1004
1005         return 0;
1006 }
1007
1008 /* Relationship between s_mode and the DT_xxx types */
1009 static inline unsigned char dt_type(struct configfs_dirent *sd)
1010 {
1011         return (sd->s_mode >> 12) & 15;
1012 }
1013
1014 static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
1015 {
1016         struct dentry *dentry = filp->f_dentry;
1017         struct configfs_dirent * parent_sd = dentry->d_fsdata;
1018         struct configfs_dirent *cursor = filp->private_data;
1019         struct list_head *p, *q = &cursor->s_sibling;
1020         ino_t ino;
1021         int i = filp->f_pos;
1022
1023         switch (i) {
1024                 case 0:
1025                         ino = dentry->d_inode->i_ino;
1026                         if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
1027                                 break;
1028                         filp->f_pos++;
1029                         i++;
1030                         /* fallthrough */
1031                 case 1:
1032                         ino = parent_ino(dentry);
1033                         if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
1034                                 break;
1035                         filp->f_pos++;
1036                         i++;
1037                         /* fallthrough */
1038                 default:
1039                         if (filp->f_pos == 2) {
1040                                 list_move(q, &parent_sd->s_children);
1041                         }
1042                         for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
1043                                 struct configfs_dirent *next;
1044                                 const char * name;
1045                                 int len;
1046
1047                                 next = list_entry(p, struct configfs_dirent,
1048                                                    s_sibling);
1049                                 if (!next->s_element)
1050                                         continue;
1051
1052                                 name = configfs_get_name(next);
1053                                 len = strlen(name);
1054                                 if (next->s_dentry)
1055                                         ino = next->s_dentry->d_inode->i_ino;
1056                                 else
1057                                         ino = iunique(configfs_sb, 2);
1058
1059                                 if (filldir(dirent, name, len, filp->f_pos, ino,
1060                                                  dt_type(next)) < 0)
1061                                         return 0;
1062
1063                                 list_move(q, p);
1064                                 p = q;
1065                                 filp->f_pos++;
1066                         }
1067         }
1068         return 0;
1069 }
1070
1071 static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin)
1072 {
1073         struct dentry * dentry = file->f_dentry;
1074
1075         mutex_lock(&dentry->d_inode->i_mutex);
1076         switch (origin) {
1077                 case 1:
1078                         offset += file->f_pos;
1079                 case 0:
1080                         if (offset >= 0)
1081                                 break;
1082                 default:
1083                         mutex_unlock(&file->f_dentry->d_inode->i_mutex);
1084                         return -EINVAL;
1085         }
1086         if (offset != file->f_pos) {
1087                 file->f_pos = offset;
1088                 if (file->f_pos >= 2) {
1089                         struct configfs_dirent *sd = dentry->d_fsdata;
1090                         struct configfs_dirent *cursor = file->private_data;
1091                         struct list_head *p;
1092                         loff_t n = file->f_pos - 2;
1093
1094                         list_del(&cursor->s_sibling);
1095                         p = sd->s_children.next;
1096                         while (n && p != &sd->s_children) {
1097                                 struct configfs_dirent *next;
1098                                 next = list_entry(p, struct configfs_dirent,
1099                                                    s_sibling);
1100                                 if (next->s_element)
1101                                         n--;
1102                                 p = p->next;
1103                         }
1104                         list_add_tail(&cursor->s_sibling, p);
1105                 }
1106         }
1107         mutex_unlock(&dentry->d_inode->i_mutex);
1108         return offset;
1109 }
1110
1111 const struct file_operations configfs_dir_operations = {
1112         .open           = configfs_dir_open,
1113         .release        = configfs_dir_close,
1114         .llseek         = configfs_dir_lseek,
1115         .read           = generic_read_dir,
1116         .readdir        = configfs_readdir,
1117 };
1118
1119 int configfs_register_subsystem(struct configfs_subsystem *subsys)
1120 {
1121         int err;
1122         struct config_group *group = &subsys->su_group;
1123         struct qstr name;
1124         struct dentry *dentry;
1125         struct configfs_dirent *sd;
1126
1127         err = configfs_pin_fs();
1128         if (err)
1129                 return err;
1130
1131         if (!group->cg_item.ci_name)
1132                 group->cg_item.ci_name = group->cg_item.ci_namebuf;
1133
1134         sd = configfs_sb->s_root->d_fsdata;
1135         link_group(to_config_group(sd->s_element), group);
1136
1137         mutex_lock(&configfs_sb->s_root->d_inode->i_mutex);
1138
1139         name.name = group->cg_item.ci_name;
1140         name.len = strlen(name.name);
1141         name.hash = full_name_hash(name.name, name.len);
1142
1143         err = -ENOMEM;
1144         dentry = d_alloc(configfs_sb->s_root, &name);
1145         if (!dentry)
1146                 goto out_release;
1147
1148         d_add(dentry, NULL);
1149
1150         err = configfs_attach_group(sd->s_element, &group->cg_item,
1151                                     dentry);
1152         if (!err)
1153                 dentry = NULL;
1154         else
1155                 d_delete(dentry);
1156
1157         mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1158
1159         if (dentry) {
1160             dput(dentry);
1161 out_release:
1162             unlink_group(group);
1163             configfs_release_fs();
1164         }
1165
1166         return err;
1167 }
1168
1169 void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
1170 {
1171         struct config_group *group = &subsys->su_group;
1172         struct dentry *dentry = group->cg_item.ci_dentry;
1173
1174         if (dentry->d_parent != configfs_sb->s_root) {
1175                 printk(KERN_ERR "configfs: Tried to unregister non-subsystem!\n");
1176                 return;
1177         }
1178
1179         mutex_lock(&configfs_sb->s_root->d_inode->i_mutex);
1180         mutex_lock(&dentry->d_inode->i_mutex);
1181         if (configfs_detach_prep(dentry)) {
1182                 printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n");
1183         }
1184         configfs_detach_group(&group->cg_item);
1185         dentry->d_inode->i_flags |= S_DEAD;
1186         mutex_unlock(&dentry->d_inode->i_mutex);
1187
1188         d_delete(dentry);
1189
1190         mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);
1191
1192         dput(dentry);
1193
1194         unlink_group(group);
1195         configfs_release_fs();
1196 }
1197
1198 EXPORT_SYMBOL(configfs_register_subsystem);
1199 EXPORT_SYMBOL(configfs_unregister_subsystem);