fs/sysfs/dir.c

   1 /*
   2  * dir.c - Operations for sysfs directories.
   3  */
   4
   5 #undef DEBUG
   6
   7 #include <linux/fs.h>
   8 #include <linux/mount.h>
   9 #include <linux/module.h>
  10 #include <linux/kobject.h>
  11 #include <linux/namei.h>
  12 #include <linux/idr.h>
  13 #include <asm/semaphore.h>
  14 #include "sysfs.h"
  15
  16 DECLARE_RWSEM(sysfs_rename_sem);
  17 spinlock_t sysfs_lock = SPIN_LOCK_UNLOCKED;
  18
  19 static spinlock_t sysfs_ino_lock = SPIN_LOCK_UNLOCKED;
  20 static DEFINE_IDA(sysfs_ino_ida);
  21
  22 int sysfs_alloc_ino(ino_t *pino)
  23 {
  24         int ino, rc;
  25
  26  retry:
  27         spin_lock(&sysfs_ino_lock);
  28         rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino);
  29         spin_unlock(&sysfs_ino_lock);
  30
  31         if (rc == -EAGAIN) {
  32                 if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL))
  33                         goto retry;
  34                 rc = -ENOMEM;
  35         }
  36
  37         *pino = ino;
  38         return rc;
  39 }
  40
  41 static void sysfs_free_ino(ino_t ino)
  42 {
  43         spin_lock(&sysfs_ino_lock);
  44         ida_remove(&sysfs_ino_ida, ino);
  45         spin_unlock(&sysfs_ino_lock);
  46 }
  47
  48 void release_sysfs_dirent(struct sysfs_dirent * sd)
  49 {
  50         if (sd->s_type & SYSFS_KOBJ_LINK) {
  51                 struct sysfs_symlink * sl = sd->s_element;
  52                 kfree(sl->link_name);
  53                 kobject_put(sl->target_kobj);
  54                 kfree(sl);
  55         }
  56         kfree(sd->s_iattr);
  57         sysfs_free_ino(sd->s_ino);
  58         kmem_cache_free(sysfs_dir_cachep, sd);
  59 }
  60
  61 static void sysfs_d_iput(struct dentry * dentry, struct inode * inode)
  62 {
  63         struct sysfs_dirent * sd = dentry->d_fsdata;
  64
  65         if (sd) {
  66                 /* sd->s_dentry is protected with sysfs_lock.  This
  67                  * allows sysfs_drop_dentry() to dereference it.
  68                  */
  69                 spin_lock(&sysfs_lock);
  70
  71                 /* The dentry might have been deleted or another
  72                  * lookup could have happened updating sd->s_dentry to
  73                  * point the new dentry.  Ignore if it isn't pointing
  74                  * to this dentry.
  75                  */
  76                 if (sd->s_dentry == dentry)
  77                         sd->s_dentry = NULL;
  78                 spin_unlock(&sysfs_lock);
  79                 sysfs_put(sd);
  80         }
  81         iput(inode);
  82 }
  83
  84 static struct dentry_operations sysfs_dentry_ops = {
  85         .d_iput         = sysfs_d_iput,
  86 };
  87
  88 struct sysfs_dirent *sysfs_new_dirent(void *element, umode_t mode, int type)
  89 {
  90         struct sysfs_dirent * sd;
  91
  92         sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
  93         if (!sd)
  94                 return NULL;
  95
  96         if (sysfs_alloc_ino(&sd->s_ino)) {
  97                 kmem_cache_free(sysfs_dir_cachep, sd);
  98                 return NULL;
  99         }
 100
 101         atomic_set(&sd->s_count, 1);
 102         atomic_set(&sd->s_event, 1);
 103         INIT_LIST_HEAD(&sd->s_children);
 104         INIT_LIST_HEAD(&sd->s_sibling);
 105
 106         sd->s_element = element;
 107         sd->s_mode = mode;
 108         sd->s_type = type;
 109
 110         return sd;
 111 }
 112
 113 void sysfs_attach_dirent(struct sysfs_dirent *sd,
 114                          struct sysfs_dirent *parent_sd, struct dentry *dentry)
 115 {
 116         if (dentry) {
 117                 sd->s_dentry = dentry;
 118                 dentry->d_fsdata = sysfs_get(sd);
 119                 dentry->d_op = &sysfs_dentry_ops;
 120         }
 121
 122         if (parent_sd)
 123                 list_add(&sd->s_sibling, &parent_sd->s_children);
 124 }
 125
 126 /*
 127  *
 128  * Return -EEXIST if there is already a sysfs element with the same name for
 129  * the same parent.
 130  *
 131  * called with parent inode's i_mutex held
 132  */
 133 int sysfs_dirent_exist(struct sysfs_dirent *parent_sd,
 134                           const unsigned char *new)
 135 {
 136         struct sysfs_dirent * sd;
 137
 138         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 139                 if (sd->s_element) {
 140                         const unsigned char *existing = sysfs_get_name(sd);
 141                         if (strcmp(existing, new))
 142                                 continue;
 143                         else
 144                                 return -EEXIST;
 145                 }
 146         }
 147
 148         return 0;
 149 }
 150
 151 static int init_dir(struct inode * inode)
 152 {
 153         inode->i_op = &sysfs_dir_inode_operations;
 154         inode->i_fop = &sysfs_dir_operations;
 155
 156         /* directory inodes start off with i_nlink == 2 (for "." entry) */
 157         inc_nlink(inode);
 158         return 0;
 159 }
 160
 161 static int init_file(struct inode * inode)
 162 {
 163         inode->i_size = PAGE_SIZE;
 164         inode->i_fop = &sysfs_file_operations;
 165         return 0;
 166 }
 167
 168 static int init_symlink(struct inode * inode)
 169 {
 170         inode->i_op = &sysfs_symlink_inode_operations;
 171         return 0;
 172 }
 173
 174 static int create_dir(struct kobject *kobj, struct dentry *parent,
 175                       const char *name, struct dentry **p_dentry)
 176 {
 177         int error;
 178         umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
 179         struct dentry *dentry;
 180         struct sysfs_dirent *sd;
 181
 182         mutex_lock(&parent->d_inode->i_mutex);
 183
 184         dentry = lookup_one_len(name, parent, strlen(name));
 185         if (IS_ERR(dentry)) {
 186                 error = PTR_ERR(dentry);
 187                 goto out_unlock;
 188         }
 189
 190         error = -EEXIST;
 191         if (sysfs_dirent_exist(parent->d_fsdata, name))
 192                 goto out_dput;
 193
 194         error = -ENOMEM;
 195         sd = sysfs_new_dirent(kobj, mode, SYSFS_DIR);
 196         if (!sd)
 197                 goto out_drop;
 198         sysfs_attach_dirent(sd, parent->d_fsdata, dentry);
 199
 200         error = sysfs_create(dentry, mode, init_dir);
 201         if (error)
 202                 goto out_sput;
 203
 204         inc_nlink(parent->d_inode);
 205         dentry->d_op = &sysfs_dentry_ops;
 206         d_rehash(dentry);
 207
 208         *p_dentry = dentry;
 209         error = 0;
 210         goto out_dput;
 211
 212  out_sput:
 213         list_del_init(&sd->s_sibling);
 214         sysfs_put(sd);
 215  out_drop:
 216         d_drop(dentry);
 217  out_dput:
 218         dput(dentry);
 219  out_unlock:
 220         mutex_unlock(&parent->d_inode->i_mutex);
 221         return error;
 222 }
 223
 224
 225 int sysfs_create_subdir(struct kobject * k, const char * n, struct dentry ** d)
 226 {
 227         return create_dir(k,k->dentry,n,d);
 228 }
 229
 230 /**
 231  *      sysfs_create_dir - create a directory for an object.
 232  *      @kobj:          object we're creating directory for.
 233  *      @shadow_parent: parent parent object.
 234  */
 235
 236 int sysfs_create_dir(struct kobject * kobj, struct dentry *shadow_parent)
 237 {
 238         struct dentry * dentry = NULL;
 239         struct dentry * parent;
 240         int error = 0;
 241
 242         BUG_ON(!kobj);
 243
 244         if (shadow_parent)
 245                 parent = shadow_parent;
 246         else if (kobj->parent)
 247                 parent = kobj->parent->dentry;
 248         else if (sysfs_mount && sysfs_mount->mnt_sb)
 249                 parent = sysfs_mount->mnt_sb->s_root;
 250         else
 251                 return -EFAULT;
 252
 253         error = create_dir(kobj,parent,kobject_name(kobj),&dentry);
 254         if (!error)
 255                 kobj->dentry = dentry;
 256         return error;
 257 }
 258
 259 /* attaches attribute's sysfs_dirent to the dentry corresponding to the
 260  * attribute file
 261  */
 262 static int sysfs_attach_attr(struct sysfs_dirent * sd, struct dentry * dentry)
 263 {
 264         struct attribute * attr = NULL;
 265         struct bin_attribute * bin_attr = NULL;
 266         int (* init) (struct inode *) = NULL;
 267         int error = 0;
 268
 269         if (sd->s_type & SYSFS_KOBJ_BIN_ATTR) {
 270                 bin_attr = sd->s_element;
 271                 attr = &bin_attr->attr;
 272         } else {
 273                 attr = sd->s_element;
 274                 init = init_file;
 275         }
 276
 277         dentry->d_fsdata = sysfs_get(sd);
 278         /* protect sd->s_dentry against sysfs_d_iput */
 279         spin_lock(&sysfs_lock);
 280         sd->s_dentry = dentry;
 281         spin_unlock(&sysfs_lock);
 282         error = sysfs_create(dentry, (attr->mode & S_IALLUGO) | S_IFREG, init);
 283         if (error) {
 284                 sysfs_put(sd);
 285                 return error;
 286         }
 287
 288         if (bin_attr) {
 289                 dentry->d_inode->i_size = bin_attr->size;
 290                 dentry->d_inode->i_fop = &bin_fops;
 291         }
 292         dentry->d_op = &sysfs_dentry_ops;
 293         d_rehash(dentry);
 294
 295         return 0;
 296 }
 297
 298 static int sysfs_attach_link(struct sysfs_dirent * sd, struct dentry * dentry)
 299 {
 300         int err = 0;
 301
 302         dentry->d_fsdata = sysfs_get(sd);
 303         /* protect sd->s_dentry against sysfs_d_iput */
 304         spin_lock(&sysfs_lock);
 305         sd->s_dentry = dentry;
 306         spin_unlock(&sysfs_lock);
 307         err = sysfs_create(dentry, S_IFLNK|S_IRWXUGO, init_symlink);
 308         if (!err) {
 309                 dentry->d_op = &sysfs_dentry_ops;
 310                 d_rehash(dentry);
 311         } else
 312                 sysfs_put(sd);
 313
 314         return err;
 315 }
 316
 317 static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
 318                                 struct nameidata *nd)
 319 {
 320         struct sysfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
 321         struct sysfs_dirent * sd;
 322         int err = 0;
 323
 324         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 325                 if (sd->s_type & SYSFS_NOT_PINNED) {
 326                         const unsigned char * name = sysfs_get_name(sd);
 327
 328                         if (strcmp(name, dentry->d_name.name))
 329                                 continue;
 330
 331                         if (sd->s_type & SYSFS_KOBJ_LINK)
 332                                 err = sysfs_attach_link(sd, dentry);
 333                         else
 334                                 err = sysfs_attach_attr(sd, dentry);
 335                         break;
 336                 }
 337         }
 338
 339         return ERR_PTR(err);
 340 }
 341
 342 const struct inode_operations sysfs_dir_inode_operations = {
 343         .lookup         = sysfs_lookup,
 344         .setattr        = sysfs_setattr,
 345 };
 346
 347 static void remove_dir(struct dentry * d)
 348 {
 349         struct dentry * parent = dget(d->d_parent);
 350         struct sysfs_dirent * sd;
 351
 352         mutex_lock(&parent->d_inode->i_mutex);
 353         d_delete(d);
 354         sd = d->d_fsdata;
 355         list_del_init(&sd->s_sibling);
 356         sysfs_put(sd);
 357         if (d->d_inode)
 358                 simple_rmdir(parent->d_inode,d);
 359
 360         pr_debug(" o %s removing done (%d)\n",d->d_name.name,
 361                  atomic_read(&d->d_count));
 362
 363         mutex_unlock(&parent->d_inode->i_mutex);
 364         dput(parent);
 365 }
 366
 367 void sysfs_remove_subdir(struct dentry * d)
 368 {
 369         remove_dir(d);
 370 }
 371
 372
 373 static void __sysfs_remove_dir(struct dentry *dentry)
 374 {
 375         struct sysfs_dirent * parent_sd;
 376         struct sysfs_dirent * sd, * tmp;
 377
 378         dget(dentry);
 379         if (!dentry)
 380                 return;
 381
 382         pr_debug("sysfs %s: removing dir\n",dentry->d_name.name);
 383         mutex_lock(&dentry->d_inode->i_mutex);
 384         parent_sd = dentry->d_fsdata;
 385         list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
 386                 if (!sd->s_element || !(sd->s_type & SYSFS_NOT_PINNED))
 387                         continue;
 388                 list_del_init(&sd->s_sibling);
 389                 sysfs_drop_dentry(sd, dentry);
 390                 sysfs_put(sd);
 391         }
 392         mutex_unlock(&dentry->d_inode->i_mutex);
 393
 394         remove_dir(dentry);
 395         /**
 396          * Drop reference from dget() on entrance.
 397          */
 398         dput(dentry);
 399 }
 400
 401 /**
 402  *      sysfs_remove_dir - remove an object's directory.
 403  *      @kobj:  object.
 404  *
 405  *      The only thing special about this is that we remove any files in
 406  *      the directory before we remove the directory, and we've inlined
 407  *      what used to be sysfs_rmdir() below, instead of calling separately.
 408  */
 409
 410 void sysfs_remove_dir(struct kobject * kobj)
 411 {
 412         __sysfs_remove_dir(kobj->dentry);
 413         kobj->dentry = NULL;
 414 }
 415
 416 int sysfs_rename_dir(struct kobject * kobj, struct dentry *new_parent,
 417                      const char *new_name)
 418 {
 419         int error;
 420         struct dentry * new_dentry;
 421         struct sysfs_dirent *sd, *parent_sd;
 422
 423         if (!new_parent)
 424                 return -EFAULT;
 425
 426         down_write(&sysfs_rename_sem);
 427         mutex_lock(&new_parent->d_inode->i_mutex);
 428
 429         new_dentry = lookup_one_len(new_name, new_parent, strlen(new_name));
 430         if (IS_ERR(new_dentry)) {
 431                 error = PTR_ERR(new_dentry);
 432                 goto out_unlock;
 433         }
 434
 435         /* By allowing two different directories with the same
 436          * d_parent we allow this routine to move between different
 437          * shadows of the same directory
 438          */
 439         error = -EINVAL;
 440         if (kobj->dentry->d_parent->d_inode != new_parent->d_inode ||
 441             new_dentry->d_parent->d_inode != new_parent->d_inode ||
 442             new_dentry == kobj->dentry)
 443                 goto out_dput;
 444
 445         error = -EEXIST;
 446         if (new_dentry->d_inode)
 447                 goto out_dput;
 448
 449         error = kobject_set_name(kobj, "%s", new_name);
 450         if (error)
 451                 goto out_drop;
 452
 453         d_add(new_dentry, NULL);
 454         d_move(kobj->dentry, new_dentry);
 455
 456         sd = kobj->dentry->d_fsdata;
 457         parent_sd = new_parent->d_fsdata;
 458
 459         list_del_init(&sd->s_sibling);
 460         list_add(&sd->s_sibling, &parent_sd->s_children);
 461
 462         error = 0;
 463         goto out_unlock;
 464
 465  out_drop:
 466         d_drop(new_dentry);
 467  out_dput:
 468         dput(new_dentry);
 469  out_unlock:
 470         mutex_unlock(&new_parent->d_inode->i_mutex);
 471         up_write(&sysfs_rename_sem);
 472         return error;
 473 }
 474
 475 int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent)
 476 {
 477         struct dentry *old_parent_dentry, *new_parent_dentry, *new_dentry;
 478         struct sysfs_dirent *new_parent_sd, *sd;
 479         int error;
 480
 481         old_parent_dentry = kobj->parent ?
 482                 kobj->parent->dentry : sysfs_mount->mnt_sb->s_root;
 483         new_parent_dentry = new_parent ?
 484                 new_parent->dentry : sysfs_mount->mnt_sb->s_root;
 485
 486         if (old_parent_dentry->d_inode == new_parent_dentry->d_inode)
 487                 return 0;       /* nothing to move */
 488 again:
 489         mutex_lock(&old_parent_dentry->d_inode->i_mutex);
 490         if (!mutex_trylock(&new_parent_dentry->d_inode->i_mutex)) {
 491                 mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
 492                 goto again;
 493         }
 494
 495         new_parent_sd = new_parent_dentry->d_fsdata;
 496         sd = kobj->dentry->d_fsdata;
 497
 498         new_dentry = lookup_one_len(kobj->name, new_parent_dentry,
 499                                     strlen(kobj->name));
 500         if (IS_ERR(new_dentry)) {
 501                 error = PTR_ERR(new_dentry);
 502                 goto out;
 503         } else
 504                 error = 0;
 505         d_add(new_dentry, NULL);
 506         d_move(kobj->dentry, new_dentry);
 507         dput(new_dentry);
 508
 509         /* Remove from old parent's list and insert into new parent's list. */
 510         list_del_init(&sd->s_sibling);
 511         list_add(&sd->s_sibling, &new_parent_sd->s_children);
 512
 513 out:
 514         mutex_unlock(&new_parent_dentry->d_inode->i_mutex);
 515         mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
 516
 517         return error;
 518 }
 519
 520 static int sysfs_dir_open(struct inode *inode, struct file *file)
 521 {
 522         struct dentry * dentry = file->f_path.dentry;
 523         struct sysfs_dirent * parent_sd = dentry->d_fsdata;
 524         struct sysfs_dirent * sd;
 525
 526         mutex_lock(&dentry->d_inode->i_mutex);
 527         sd = sysfs_new_dirent(NULL, 0, 0);
 528         if (sd)
 529                 sysfs_attach_dirent(sd, parent_sd, NULL);
 530         mutex_unlock(&dentry->d_inode->i_mutex);
 531
 532         file->private_data = sd;
 533         return sd ? 0 : -ENOMEM;
 534 }
 535
 536 static int sysfs_dir_close(struct inode *inode, struct file *file)
 537 {
 538         struct dentry * dentry = file->f_path.dentry;
 539         struct sysfs_dirent * cursor = file->private_data;
 540
 541         mutex_lock(&dentry->d_inode->i_mutex);
 542         list_del_init(&cursor->s_sibling);
 543         mutex_unlock(&dentry->d_inode->i_mutex);
 544
 545         release_sysfs_dirent(cursor);
 546
 547         return 0;
 548 }
 549
 550 /* Relationship between s_mode and the DT_xxx types */
 551 static inline unsigned char dt_type(struct sysfs_dirent *sd)
 552 {
 553         return (sd->s_mode >> 12) & 15;
 554 }
 555
 556 static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
 557 {
 558         struct dentry *dentry = filp->f_path.dentry;
 559         struct sysfs_dirent * parent_sd = dentry->d_fsdata;
 560         struct sysfs_dirent *cursor = filp->private_data;
 561         struct list_head *p, *q = &cursor->s_sibling;
 562         ino_t ino;
 563         int i = filp->f_pos;
 564
 565         switch (i) {
 566                 case 0:
 567                         ino = parent_sd->s_ino;
 568                         if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
 569                                 break;
 570                         filp->f_pos++;
 571                         i++;
 572                         /* fallthrough */
 573                 case 1:
 574                         ino = parent_ino(dentry);
 575                         if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
 576                                 break;
 577                         filp->f_pos++;
 578                         i++;
 579                         /* fallthrough */
 580                 default:
 581                         if (filp->f_pos == 2)
 582                                 list_move(q, &parent_sd->s_children);
 583
 584                         for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
 585                                 struct sysfs_dirent *next;
 586                                 const char * name;
 587                                 int len;
 588
 589                                 next = list_entry(p, struct sysfs_dirent,
 590                                                    s_sibling);
 591                                 if (!next->s_element)
 592                                         continue;
 593
 594                                 name = sysfs_get_name(next);
 595                                 len = strlen(name);
 596                                 ino = next->s_ino;
 597
 598                                 if (filldir(dirent, name, len, filp->f_pos, ino,
 599                                                  dt_type(next)) < 0)
 600                                         return 0;
 601
 602                                 list_move(q, p);
 603                                 p = q;
 604                                 filp->f_pos++;
 605                         }
 606         }
 607         return 0;
 608 }
 609
 610 static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
 611 {
 612         struct dentry * dentry = file->f_path.dentry;
 613
 614         mutex_lock(&dentry->d_inode->i_mutex);
 615         switch (origin) {
 616                 case 1:
 617                         offset += file->f_pos;
 618                 case 0:
 619                         if (offset >= 0)
 620                                 break;
 621                 default:
 622                         mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
 623                         return -EINVAL;
 624         }
 625         if (offset != file->f_pos) {
 626                 file->f_pos = offset;
 627                 if (file->f_pos >= 2) {
 628                         struct sysfs_dirent *sd = dentry->d_fsdata;
 629                         struct sysfs_dirent *cursor = file->private_data;
 630                         struct list_head *p;
 631                         loff_t n = file->f_pos - 2;
 632
 633                         list_del(&cursor->s_sibling);
 634                         p = sd->s_children.next;
 635                         while (n && p != &sd->s_children) {
 636                                 struct sysfs_dirent *next;
 637                                 next = list_entry(p, struct sysfs_dirent,
 638                                                    s_sibling);
 639                                 if (next->s_element)
 640                                         n--;
 641                                 p = p->next;
 642                         }
 643                         list_add_tail(&cursor->s_sibling, p);
 644                 }
 645         }
 646         mutex_unlock(&dentry->d_inode->i_mutex);
 647         return offset;
 648 }
 649
 650
 651 /**
 652  *      sysfs_make_shadowed_dir - Setup so a directory can be shadowed
 653  *      @kobj:  object we're creating shadow of.
 654  */
 655
 656 int sysfs_make_shadowed_dir(struct kobject *kobj,
 657         void * (*follow_link)(struct dentry *, struct nameidata *))
 658 {
 659         struct inode *inode;
 660         struct inode_operations *i_op;
 661
 662         inode = kobj->dentry->d_inode;
 663         if (inode->i_op != &sysfs_dir_inode_operations)
 664                 return -EINVAL;
 665
 666         i_op = kmalloc(sizeof(*i_op), GFP_KERNEL);
 667         if (!i_op)
 668                 return -ENOMEM;
 669
 670         memcpy(i_op, &sysfs_dir_inode_operations, sizeof(*i_op));
 671         i_op->follow_link = follow_link;
 672
 673         /* Locking of inode->i_op?
 674          * Since setting i_op is a single word write and they
 675          * are atomic we should be ok here.
 676          */
 677         inode->i_op = i_op;
 678         return 0;
 679 }
 680
 681 /**
 682  *      sysfs_create_shadow_dir - create a shadow directory for an object.
 683  *      @kobj:  object we're creating directory for.
 684  *
 685  *      sysfs_make_shadowed_dir must already have been called on this
 686  *      directory.
 687  */
 688
 689 struct dentry *sysfs_create_shadow_dir(struct kobject *kobj)
 690 {
 691         struct sysfs_dirent *sd;
 692         struct dentry *parent, *dir, *shadow;
 693         struct inode *inode;
 694
 695         dir = kobj->dentry;
 696         inode = dir->d_inode;
 697         parent = dir->d_parent;
 698         shadow = ERR_PTR(-EINVAL);
 699         if (!sysfs_is_shadowed_inode(inode))
 700                 goto out;
 701
 702         shadow = d_alloc(parent, &dir->d_name);
 703         if (!shadow)
 704                 goto nomem;
 705
 706         sd = sysfs_new_dirent(kobj, inode->i_mode, SYSFS_DIR);
 707         if (!sd)
 708                 goto nomem;
 709         sysfs_attach_dirent(sd, NULL, shadow);
 710
 711         d_instantiate(shadow, igrab(inode));
 712         inc_nlink(inode);
 713         inc_nlink(parent->d_inode);
 714         shadow->d_op = &sysfs_dentry_ops;
 715
 716         dget(shadow);           /* Extra count - pin the dentry in core */
 717
 718 out:
 719         return shadow;
 720 nomem:
 721         dput(shadow);
 722         shadow = ERR_PTR(-ENOMEM);
 723         goto out;
 724 }
 725
 726 /**
 727  *      sysfs_remove_shadow_dir - remove an object's directory.
 728  *      @shadow: dentry of shadow directory
 729  *
 730  *      The only thing special about this is that we remove any files in
 731  *      the directory before we remove the directory, and we've inlined
 732  *      what used to be sysfs_rmdir() below, instead of calling separately.
 733  */
 734
 735 void sysfs_remove_shadow_dir(struct dentry *shadow)
 736 {
 737         __sysfs_remove_dir(shadow);
 738 }
 739
 740 const struct file_operations sysfs_dir_operations = {
 741         .open           = sysfs_dir_open,
 742         .release        = sysfs_dir_close,
 743         .llseek         = sysfs_dir_lseek,
 744         .read           = generic_read_dir,
 745         .readdir        = sysfs_readdir,
 746 };