fs/sysfs/dir.c

   1 /*
   2  * fs/sysfs/dir.c - sysfs core and dir operation implementation
   3  *
   4  * Copyright (c) 2001-3 Patrick Mochel
   5  * Copyright (c) 2007 SUSE Linux Products GmbH
   6  * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
   7  *
   8  * This file is released under the GPLv2.
   9  *
  10  * Please see Documentation/filesystems/sysfs.txt for more information.
  11  */
  12
  13 #undef DEBUG
  14
  15 #include <linux/fs.h>
  16 #include <linux/mount.h>
  17 #include <linux/module.h>
  18 #include <linux/kobject.h>
  19 #include <linux/namei.h>
  20 #include <linux/idr.h>
  21 #include <linux/completion.h>
  22 #include <linux/mutex.h>
  23 #include <linux/slab.h>
  24 #include <linux/security.h>
  25 #include "sysfs.h"
  26
  27 DEFINE_MUTEX(sysfs_mutex);
  28 DEFINE_SPINLOCK(sysfs_assoc_lock);
  29
  30 static DEFINE_SPINLOCK(sysfs_ino_lock);
  31 static DEFINE_IDA(sysfs_ino_ida);
  32
  33 /**
  34  *      sysfs_link_sibling - link sysfs_dirent into sibling list
  35  *      @sd: sysfs_dirent of interest
  36  *
  37  *      Link @sd into its sibling list which starts from
  38  *      sd->s_parent->s_dir.children.
  39  *
  40  *      Locking:
  41  *      mutex_lock(sysfs_mutex)
  42  */
  43 static void sysfs_link_sibling(struct sysfs_dirent *sd)
  44 {
  45         struct sysfs_dirent *parent_sd = sd->s_parent;
  46         struct sysfs_dirent **pos;
  47
  48         BUG_ON(sd->s_sibling);
  49
  50         /* Store directory entries in order by ino.  This allows
  51          * readdir to properly restart without having to add a
  52          * cursor into the s_dir.children list.
  53          */
  54         for (pos = &parent_sd->s_dir.children; *pos; pos = &(*pos)->s_sibling) {
  55                 if (sd->s_ino < (*pos)->s_ino)
  56                         break;
  57         }
  58         sd->s_sibling = *pos;
  59         *pos = sd;
  60 }
  61
  62 /**
  63  *      sysfs_unlink_sibling - unlink sysfs_dirent from sibling list
  64  *      @sd: sysfs_dirent of interest
  65  *
  66  *      Unlink @sd from its sibling list which starts from
  67  *      sd->s_parent->s_dir.children.
  68  *
  69  *      Locking:
  70  *      mutex_lock(sysfs_mutex)
  71  */
  72 static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
  73 {
  74         struct sysfs_dirent **pos;
  75
  76         for (pos = &sd->s_parent->s_dir.children; *pos;
  77              pos = &(*pos)->s_sibling) {
  78                 if (*pos == sd) {
  79                         *pos = sd->s_sibling;
  80                         sd->s_sibling = NULL;
  81                         break;
  82                 }
  83         }
  84 }
  85
  86 /**
  87  *      sysfs_get_active - get an active reference to sysfs_dirent
  88  *      @sd: sysfs_dirent to get an active reference to
  89  *
  90  *      Get an active reference of @sd.  This function is noop if @sd
  91  *      is NULL.
  92  *
  93  *      RETURNS:
  94  *      Pointer to @sd on success, NULL on failure.
  95  */
  96 struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
  97 {
  98         if (unlikely(!sd))
  99                 return NULL;
 100
 101         while (1) {
 102                 int v, t;
 103
 104                 v = atomic_read(&sd->s_active);
 105                 if (unlikely(v < 0))
 106                         return NULL;
 107
 108                 t = atomic_cmpxchg(&sd->s_active, v, v + 1);
 109                 if (likely(t == v)) {
 110                         rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_);
 111                         return sd;
 112                 }
 113                 if (t < 0)
 114                         return NULL;
 115
 116                 cpu_relax();
 117         }
 118 }
 119
 120 /**
 121  *      sysfs_put_active - put an active reference to sysfs_dirent
 122  *      @sd: sysfs_dirent to put an active reference to
 123  *
 124  *      Put an active reference to @sd.  This function is noop if @sd
 125  *      is NULL.
 126  */
 127 void sysfs_put_active(struct sysfs_dirent *sd)
 128 {
 129         struct completion *cmpl;
 130         int v;
 131
 132         if (unlikely(!sd))
 133                 return;
 134
 135         rwsem_release(&sd->dep_map, 1, _RET_IP_);
 136         v = atomic_dec_return(&sd->s_active);
 137         if (likely(v != SD_DEACTIVATED_BIAS))
 138                 return;
 139
 140         /* atomic_dec_return() is a mb(), we'll always see the updated
 141          * sd->s_sibling.
 142          */
 143         cmpl = (void *)sd->s_sibling;
 144         complete(cmpl);
 145 }
 146
 147 /**
 148  *      sysfs_deactivate - deactivate sysfs_dirent
 149  *      @sd: sysfs_dirent to deactivate
 150  *
 151  *      Deny new active references and drain existing ones.
 152  */
 153 static void sysfs_deactivate(struct sysfs_dirent *sd)
 154 {
 155         DECLARE_COMPLETION_ONSTACK(wait);
 156         int v;
 157
 158         BUG_ON(sd->s_sibling || !(sd->s_flags & SYSFS_FLAG_REMOVED));
 159
 160         if (!(sysfs_type(sd) & SYSFS_ACTIVE_REF))
 161                 return;
 162
 163         sd->s_sibling = (void *)&wait;
 164
 165         rwsem_acquire(&sd->dep_map, 0, 0, _RET_IP_);
 166         /* atomic_add_return() is a mb(), put_active() will always see
 167          * the updated sd->s_sibling.
 168          */
 169         v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active);
 170
 171         if (v != SD_DEACTIVATED_BIAS) {
 172                 lock_contended(&sd->dep_map, _RET_IP_);
 173                 wait_for_completion(&wait);
 174         }
 175
 176         sd->s_sibling = NULL;
 177
 178         lock_acquired(&sd->dep_map, _RET_IP_);
 179         rwsem_release(&sd->dep_map, 1, _RET_IP_);
 180 }
 181
 182 static int sysfs_alloc_ino(ino_t *pino)
 183 {
 184         int ino, rc;
 185
 186  retry:
 187         spin_lock(&sysfs_ino_lock);
 188         rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino);
 189         spin_unlock(&sysfs_ino_lock);
 190
 191         if (rc == -EAGAIN) {
 192                 if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL))
 193                         goto retry;
 194                 rc = -ENOMEM;
 195         }
 196
 197         *pino = ino;
 198         return rc;
 199 }
 200
 201 static void sysfs_free_ino(ino_t ino)
 202 {
 203         spin_lock(&sysfs_ino_lock);
 204         ida_remove(&sysfs_ino_ida, ino);
 205         spin_unlock(&sysfs_ino_lock);
 206 }
 207
 208 void release_sysfs_dirent(struct sysfs_dirent * sd)
 209 {
 210         struct sysfs_dirent *parent_sd;
 211
 212  repeat:
 213         /* Moving/renaming is always done while holding reference.
 214          * sd->s_parent won't change beneath us.
 215          */
 216         parent_sd = sd->s_parent;
 217
 218         if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
 219                 sysfs_put(sd->s_symlink.target_sd);
 220         if (sysfs_type(sd) & SYSFS_COPY_NAME)
 221                 kfree(sd->s_name);
 222         if (sd->s_iattr && sd->s_iattr->ia_secdata)
 223                 security_release_secctx(sd->s_iattr->ia_secdata,
 224                                         sd->s_iattr->ia_secdata_len);
 225         kfree(sd->s_iattr);
 226         sysfs_free_ino(sd->s_ino);
 227         kmem_cache_free(sysfs_dir_cachep, sd);
 228
 229         sd = parent_sd;
 230         if (sd && atomic_dec_and_test(&sd->s_count))
 231                 goto repeat;
 232 }
 233
 234 static int sysfs_dentry_delete(struct dentry *dentry)
 235 {
 236         struct sysfs_dirent *sd = dentry->d_fsdata;
 237         return !!(sd->s_flags & SYSFS_FLAG_REMOVED);
 238 }
 239
 240 static int sysfs_dentry_revalidate(struct dentry *dentry, struct nameidata *nd)
 241 {
 242         struct sysfs_dirent *sd = dentry->d_fsdata;
 243         int is_dir;
 244
 245         mutex_lock(&sysfs_mutex);
 246
 247         /* The sysfs dirent has been deleted */
 248         if (sd->s_flags & SYSFS_FLAG_REMOVED)
 249                 goto out_bad;
 250
 251         /* The sysfs dirent has been moved? */
 252         if (dentry->d_parent->d_fsdata != sd->s_parent)
 253                 goto out_bad;
 254
 255         /* The sysfs dirent has been renamed */
 256         if (strcmp(dentry->d_name.name, sd->s_name) != 0)
 257                 goto out_bad;
 258
 259         mutex_unlock(&sysfs_mutex);
 260 out_valid:
 261         return 1;
 262 out_bad:
 263         /* Remove the dentry from the dcache hashes.
 264          * If this is a deleted dentry we use d_drop instead of d_delete
 265          * so sysfs doesn't need to cope with negative dentries.
 266          *
 267          * If this is a dentry that has simply been renamed we
 268          * use d_drop to remove it from the dcache lookup on its
 269          * old parent.  If this dentry persists later when a lookup
 270          * is performed at its new name the dentry will be readded
 271          * to the dcache hashes.
 272          */
 273         is_dir = (sysfs_type(sd) == SYSFS_DIR);
 274         mutex_unlock(&sysfs_mutex);
 275         if (is_dir) {
 276                 /* If we have submounts we must allow the vfs caches
 277                  * to lie about the state of the filesystem to prevent
 278                  * leaks and other nasty things.
 279                  */
 280                 if (have_submounts(dentry))
 281                         goto out_valid;
 282                 shrink_dcache_parent(dentry);
 283         }
 284         d_drop(dentry);
 285         return 0;
 286 }
 287
 288 static void sysfs_dentry_iput(struct dentry *dentry, struct inode *inode)
 289 {
 290         struct sysfs_dirent * sd = dentry->d_fsdata;
 291
 292         sysfs_put(sd);
 293         iput(inode);
 294 }
 295
 296 static const struct dentry_operations sysfs_dentry_ops = {
 297         .d_revalidate   = sysfs_dentry_revalidate,
 298         .d_delete       = sysfs_dentry_delete,
 299         .d_iput         = sysfs_dentry_iput,
 300 };
 301
 302 struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
 303 {
 304         char *dup_name = NULL;
 305         struct sysfs_dirent *sd;
 306
 307         if (type & SYSFS_COPY_NAME) {
 308                 name = dup_name = kstrdup(name, GFP_KERNEL);
 309                 if (!name)
 310                         return NULL;
 311         }
 312
 313         sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
 314         if (!sd)
 315                 goto err_out1;
 316
 317         if (sysfs_alloc_ino(&sd->s_ino))
 318                 goto err_out2;
 319
 320         atomic_set(&sd->s_count, 1);
 321         atomic_set(&sd->s_active, 0);
 322
 323         sd->s_name = name;
 324         sd->s_mode = mode;
 325         sd->s_flags = type;
 326
 327         return sd;
 328
 329  err_out2:
 330         kmem_cache_free(sysfs_dir_cachep, sd);
 331  err_out1:
 332         kfree(dup_name);
 333         return NULL;
 334 }
 335
 336 /**
 337  *      sysfs_addrm_start - prepare for sysfs_dirent add/remove
 338  *      @acxt: pointer to sysfs_addrm_cxt to be used
 339  *      @parent_sd: parent sysfs_dirent
 340  *
 341  *      This function is called when the caller is about to add or
 342  *      remove sysfs_dirent under @parent_sd.  This function acquires
 343  *      sysfs_mutex.  @acxt is used to keep and pass context to
 344  *      other addrm functions.
 345  *
 346  *      LOCKING:
 347  *      Kernel thread context (may sleep).  sysfs_mutex is locked on
 348  *      return.
 349  */
 350 void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
 351                        struct sysfs_dirent *parent_sd)
 352 {
 353         memset(acxt, 0, sizeof(*acxt));
 354         acxt->parent_sd = parent_sd;
 355
 356         mutex_lock(&sysfs_mutex);
 357 }
 358
 359 /**
 360  *      __sysfs_add_one - add sysfs_dirent to parent without warning
 361  *      @acxt: addrm context to use
 362  *      @sd: sysfs_dirent to be added
 363  *
 364  *      Get @acxt->parent_sd and set sd->s_parent to it and increment
 365  *      nlink of parent inode if @sd is a directory and link into the
 366  *      children list of the parent.
 367  *
 368  *      This function should be called between calls to
 369  *      sysfs_addrm_start() and sysfs_addrm_finish() and should be
 370  *      passed the same @acxt as passed to sysfs_addrm_start().
 371  *
 372  *      LOCKING:
 373  *      Determined by sysfs_addrm_start().
 374  *
 375  *      RETURNS:
 376  *      0 on success, -EEXIST if entry with the given name already
 377  *      exists.
 378  */
 379 int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
 380 {
 381         struct sysfs_inode_attrs *ps_iattr;
 382
 383         if (sysfs_find_dirent(acxt->parent_sd, sd->s_name))
 384                 return -EEXIST;
 385
 386         sd->s_parent = sysfs_get(acxt->parent_sd);
 387
 388         sysfs_link_sibling(sd);
 389
 390         /* Update timestamps on the parent */
 391         ps_iattr = acxt->parent_sd->s_iattr;
 392         if (ps_iattr) {
 393                 struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
 394                 ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
 395         }
 396
 397         return 0;
 398 }
 399
 400 /**
 401  *      sysfs_pathname - return full path to sysfs dirent
 402  *      @sd: sysfs_dirent whose path we want
 403  *      @path: caller allocated buffer
 404  *
 405  *      Gives the name "/" to the sysfs_root entry; any path returned
 406  *      is relative to wherever sysfs is mounted.
 407  *
 408  *      XXX: does no error checking on @path size
 409  */
 410 static char *sysfs_pathname(struct sysfs_dirent *sd, char *path)
 411 {
 412         if (sd->s_parent) {
 413                 sysfs_pathname(sd->s_parent, path);
 414                 strcat(path, "/");
 415         }
 416         strcat(path, sd->s_name);
 417         return path;
 418 }
 419
 420 /**
 421  *      sysfs_add_one - add sysfs_dirent to parent
 422  *      @acxt: addrm context to use
 423  *      @sd: sysfs_dirent to be added
 424  *
 425  *      Get @acxt->parent_sd and set sd->s_parent to it and increment
 426  *      nlink of parent inode if @sd is a directory and link into the
 427  *      children list of the parent.
 428  *
 429  *      This function should be called between calls to
 430  *      sysfs_addrm_start() and sysfs_addrm_finish() and should be
 431  *      passed the same @acxt as passed to sysfs_addrm_start().
 432  *
 433  *      LOCKING:
 434  *      Determined by sysfs_addrm_start().
 435  *
 436  *      RETURNS:
 437  *      0 on success, -EEXIST if entry with the given name already
 438  *      exists.
 439  */
 440 int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
 441 {
 442         int ret;
 443
 444         ret = __sysfs_add_one(acxt, sd);
 445         if (ret == -EEXIST) {
 446                 char *path = kzalloc(PATH_MAX, GFP_KERNEL);
 447                 WARN(1, KERN_WARNING
 448                      "sysfs: cannot create duplicate filename '%s'\n",
 449                      (path == NULL) ? sd->s_name :
 450                      strcat(strcat(sysfs_pathname(acxt->parent_sd, path), "/"),
 451                             sd->s_name));
 452                 kfree(path);
 453         }
 454
 455         return ret;
 456 }
 457
 458 /**
 459  *      sysfs_remove_one - remove sysfs_dirent from parent
 460  *      @acxt: addrm context to use
 461  *      @sd: sysfs_dirent to be removed
 462  *
 463  *      Mark @sd removed and drop nlink of parent inode if @sd is a
 464  *      directory.  @sd is unlinked from the children list.
 465  *
 466  *      This function should be called between calls to
 467  *      sysfs_addrm_start() and sysfs_addrm_finish() and should be
 468  *      passed the same @acxt as passed to sysfs_addrm_start().
 469  *
 470  *      LOCKING:
 471  *      Determined by sysfs_addrm_start().
 472  */
 473 void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
 474 {
 475         struct sysfs_inode_attrs *ps_iattr;
 476
 477         BUG_ON(sd->s_flags & SYSFS_FLAG_REMOVED);
 478
 479         sysfs_unlink_sibling(sd);
 480
 481         /* Update timestamps on the parent */
 482         ps_iattr = acxt->parent_sd->s_iattr;
 483         if (ps_iattr) {
 484                 struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
 485                 ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
 486         }
 487
 488         sd->s_flags |= SYSFS_FLAG_REMOVED;
 489         sd->s_sibling = acxt->removed;
 490         acxt->removed = sd;
 491 }
 492
 493 /**
 494  *      sysfs_addrm_finish - finish up sysfs_dirent add/remove
 495  *      @acxt: addrm context to finish up
 496  *
 497  *      Finish up sysfs_dirent add/remove.  Resources acquired by
 498  *      sysfs_addrm_start() are released and removed sysfs_dirents are
 499  *      cleaned up.
 500  *
 501  *      LOCKING:
 502  *      sysfs_mutex is released.
 503  */
 504 void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
 505 {
 506         /* release resources acquired by sysfs_addrm_start() */
 507         mutex_unlock(&sysfs_mutex);
 508
 509         /* kill removed sysfs_dirents */
 510         while (acxt->removed) {
 511                 struct sysfs_dirent *sd = acxt->removed;
 512
 513                 acxt->removed = sd->s_sibling;
 514                 sd->s_sibling = NULL;
 515
 516                 sysfs_deactivate(sd);
 517                 unmap_bin_file(sd);
 518                 sysfs_put(sd);
 519         }
 520 }
 521
 522 /**
 523  *      sysfs_find_dirent - find sysfs_dirent with the given name
 524  *      @parent_sd: sysfs_dirent to search under
 525  *      @name: name to look for
 526  *
 527  *      Look for sysfs_dirent with name @name under @parent_sd.
 528  *
 529  *      LOCKING:
 530  *      mutex_lock(sysfs_mutex)
 531  *
 532  *      RETURNS:
 533  *      Pointer to sysfs_dirent if found, NULL if not.
 534  */
 535 struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
 536                                        const unsigned char *name)
 537 {
 538         struct sysfs_dirent *sd;
 539
 540         for (sd = parent_sd->s_dir.children; sd; sd = sd->s_sibling)
 541                 if (!strcmp(sd->s_name, name))
 542                         return sd;
 543         return NULL;
 544 }
 545
 546 /**
 547  *      sysfs_get_dirent - find and get sysfs_dirent with the given name
 548  *      @parent_sd: sysfs_dirent to search under
 549  *      @name: name to look for
 550  *
 551  *      Look for sysfs_dirent with name @name under @parent_sd and get
 552  *      it if found.
 553  *
 554  *      LOCKING:
 555  *      Kernel thread context (may sleep).  Grabs sysfs_mutex.
 556  *
 557  *      RETURNS:
 558  *      Pointer to sysfs_dirent if found, NULL if not.
 559  */
 560 struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
 561                                       const unsigned char *name)
 562 {
 563         struct sysfs_dirent *sd;
 564
 565         mutex_lock(&sysfs_mutex);
 566         sd = sysfs_find_dirent(parent_sd, name);
 567         sysfs_get(sd);
 568         mutex_unlock(&sysfs_mutex);
 569
 570         return sd;
 571 }
 572 EXPORT_SYMBOL_GPL(sysfs_get_dirent);
 573
 574 static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
 575                       const char *name, struct sysfs_dirent **p_sd)
 576 {
 577         umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
 578         struct sysfs_addrm_cxt acxt;
 579         struct sysfs_dirent *sd;
 580         int rc;
 581
 582         /* allocate */
 583         sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
 584         if (!sd)
 585                 return -ENOMEM;
 586         sd->s_dir.kobj = kobj;
 587
 588         /* link in */
 589         sysfs_addrm_start(&acxt, parent_sd);
 590         rc = sysfs_add_one(&acxt, sd);
 591         sysfs_addrm_finish(&acxt);
 592
 593         if (rc == 0)
 594                 *p_sd = sd;
 595         else
 596                 sysfs_put(sd);
 597
 598         return rc;
 599 }
 600
 601 int sysfs_create_subdir(struct kobject *kobj, const char *name,
 602                         struct sysfs_dirent **p_sd)
 603 {
 604         return create_dir(kobj, kobj->sd, name, p_sd);
 605 }
 606
 607 /**
 608  *      sysfs_create_dir - create a directory for an object.
 609  *      @kobj:          object we're creating directory for.
 610  */
 611 int sysfs_create_dir(struct kobject * kobj)
 612 {
 613         struct sysfs_dirent *parent_sd, *sd;
 614         int error = 0;
 615
 616         BUG_ON(!kobj);
 617
 618         if (kobj->parent)
 619                 parent_sd = kobj->parent->sd;
 620         else
 621                 parent_sd = &sysfs_root;
 622
 623         error = create_dir(kobj, parent_sd, kobject_name(kobj), &sd);
 624         if (!error)
 625                 kobj->sd = sd;
 626         return error;
 627 }
 628
 629 static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
 630                                 struct nameidata *nd)
 631 {
 632         struct dentry *ret = NULL;
 633         struct sysfs_dirent *parent_sd = dentry->d_parent->d_fsdata;
 634         struct sysfs_dirent *sd;
 635         struct inode *inode;
 636
 637         mutex_lock(&sysfs_mutex);
 638
 639         sd = sysfs_find_dirent(parent_sd, dentry->d_name.name);
 640
 641         /* no such entry */
 642         if (!sd) {
 643                 ret = ERR_PTR(-ENOENT);
 644                 goto out_unlock;
 645         }
 646
 647         /* attach dentry and inode */
 648         inode = sysfs_get_inode(dir->i_sb, sd);
 649         if (!inode) {
 650                 ret = ERR_PTR(-ENOMEM);
 651                 goto out_unlock;
 652         }
 653
 654         /* instantiate and hash dentry */
 655         ret = d_find_alias(inode);
 656         if (!ret) {
 657                 dentry->d_op = &sysfs_dentry_ops;
 658                 dentry->d_fsdata = sysfs_get(sd);
 659                 d_add(dentry, inode);
 660         } else {
 661                 d_move(ret, dentry);
 662                 iput(inode);
 663         }
 664
 665  out_unlock:
 666         mutex_unlock(&sysfs_mutex);
 667         return ret;
 668 }
 669
 670 const struct inode_operations sysfs_dir_inode_operations = {
 671         .lookup         = sysfs_lookup,
 672         .permission     = sysfs_permission,
 673         .setattr        = sysfs_setattr,
 674         .getattr        = sysfs_getattr,
 675         .setxattr       = sysfs_setxattr,
 676 };
 677
 678 static void remove_dir(struct sysfs_dirent *sd)
 679 {
 680         struct sysfs_addrm_cxt acxt;
 681
 682         sysfs_addrm_start(&acxt, sd->s_parent);
 683         sysfs_remove_one(&acxt, sd);
 684         sysfs_addrm_finish(&acxt);
 685 }
 686
 687 void sysfs_remove_subdir(struct sysfs_dirent *sd)
 688 {
 689         remove_dir(sd);
 690 }
 691
 692
 693 static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
 694 {
 695         struct sysfs_addrm_cxt acxt;
 696         struct sysfs_dirent **pos;
 697
 698         if (!dir_sd)
 699                 return;
 700
 701         pr_debug("sysfs %s: removing dir\n", dir_sd->s_name);
 702         sysfs_addrm_start(&acxt, dir_sd);
 703         pos = &dir_sd->s_dir.children;
 704         while (*pos) {
 705                 struct sysfs_dirent *sd = *pos;
 706
 707                 if (sysfs_type(sd) != SYSFS_DIR)
 708                         sysfs_remove_one(&acxt, sd);
 709                 else
 710                         pos = &(*pos)->s_sibling;
 711         }
 712         sysfs_addrm_finish(&acxt);
 713
 714         remove_dir(dir_sd);
 715 }
 716
 717 /**
 718  *      sysfs_remove_dir - remove an object's directory.
 719  *      @kobj:  object.
 720  *
 721  *      The only thing special about this is that we remove any files in
 722  *      the directory before we remove the directory, and we've inlined
 723  *      what used to be sysfs_rmdir() below, instead of calling separately.
 724  */
 725
 726 void sysfs_remove_dir(struct kobject * kobj)
 727 {
 728         struct sysfs_dirent *sd = kobj->sd;
 729
 730         spin_lock(&sysfs_assoc_lock);
 731         kobj->sd = NULL;
 732         spin_unlock(&sysfs_assoc_lock);
 733
 734         __sysfs_remove_dir(sd);
 735 }
 736
 737 int sysfs_rename(struct sysfs_dirent *sd,
 738         struct sysfs_dirent *new_parent_sd, const char *new_name)
 739 {
 740         const char *dup_name = NULL;
 741         int error;
 742
 743         mutex_lock(&sysfs_mutex);
 744
 745         error = 0;
 746         if ((sd->s_parent == new_parent_sd) &&
 747             (strcmp(sd->s_name, new_name) == 0))
 748                 goto out;       /* nothing to rename */
 749
 750         error = -EEXIST;
 751         if (sysfs_find_dirent(new_parent_sd, new_name))
 752                 goto out;
 753
 754         /* rename sysfs_dirent */
 755         if (strcmp(sd->s_name, new_name) != 0) {
 756                 error = -ENOMEM;
 757                 new_name = dup_name = kstrdup(new_name, GFP_KERNEL);
 758                 if (!new_name)
 759                         goto out;
 760
 761                 dup_name = sd->s_name;
 762                 sd->s_name = new_name;
 763         }
 764
 765         /* Remove from old parent's list and insert into new parent's list. */
 766         if (sd->s_parent != new_parent_sd) {
 767                 sysfs_unlink_sibling(sd);
 768                 sysfs_get(new_parent_sd);
 769                 sysfs_put(sd->s_parent);
 770                 sd->s_parent = new_parent_sd;
 771                 sysfs_link_sibling(sd);
 772         }
 773
 774         error = 0;
 775  out:
 776         mutex_unlock(&sysfs_mutex);
 777         kfree(dup_name);
 778         return error;
 779 }
 780
 781 int sysfs_rename_dir(struct kobject *kobj, const char *new_name)
 782 {
 783         return sysfs_rename(kobj->sd, kobj->sd->s_parent, new_name);
 784 }
 785
 786 int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj)
 787 {
 788         struct sysfs_dirent *sd = kobj->sd;
 789         struct sysfs_dirent *new_parent_sd;
 790
 791         BUG_ON(!sd->s_parent);
 792         new_parent_sd = new_parent_kobj && new_parent_kobj->sd ?
 793                 new_parent_kobj->sd : &sysfs_root;
 794
 795         return sysfs_rename(sd, new_parent_sd, sd->s_name);
 796 }
 797
 798 /* Relationship between s_mode and the DT_xxx types */
 799 static inline unsigned char dt_type(struct sysfs_dirent *sd)
 800 {
 801         return (sd->s_mode >> 12) & 15;
 802 }
 803
 804 static int sysfs_dir_release(struct inode *inode, struct file *filp)
 805 {
 806         sysfs_put(filp->private_data);
 807         return 0;
 808 }
 809
 810 static struct sysfs_dirent *sysfs_dir_pos(struct sysfs_dirent *parent_sd,
 811         ino_t ino, struct sysfs_dirent *pos)
 812 {
 813         if (pos) {
 814                 int valid = !(pos->s_flags & SYSFS_FLAG_REMOVED) &&
 815                         pos->s_parent == parent_sd &&
 816                         ino == pos->s_ino;
 817                 sysfs_put(pos);
 818                 if (valid)
 819                         return pos;
 820         }
 821         pos = NULL;
 822         if ((ino > 1) && (ino < INT_MAX)) {
 823                 pos = parent_sd->s_dir.children;
 824                 while (pos && (ino > pos->s_ino))
 825                         pos = pos->s_sibling;
 826         }
 827         return pos;
 828 }
 829
 830 static struct sysfs_dirent *sysfs_dir_next_pos(struct sysfs_dirent *parent_sd,
 831         ino_t ino, struct sysfs_dirent *pos)
 832 {
 833         pos = sysfs_dir_pos(parent_sd, ino, pos);
 834         if (pos)
 835                 pos = pos->s_sibling;
 836         return pos;
 837 }
 838
 839 static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
 840 {
 841         struct dentry *dentry = filp->f_path.dentry;
 842         struct sysfs_dirent * parent_sd = dentry->d_fsdata;
 843         struct sysfs_dirent *pos = filp->private_data;
 844         ino_t ino;
 845
 846         if (filp->f_pos == 0) {
 847                 ino = parent_sd->s_ino;
 848                 if (filldir(dirent, ".", 1, filp->f_pos, ino, DT_DIR) == 0)
 849                         filp->f_pos++;
 850         }
 851         if (filp->f_pos == 1) {
 852                 if (parent_sd->s_parent)
 853                         ino = parent_sd->s_parent->s_ino;
 854                 else
 855                         ino = parent_sd->s_ino;
 856                 if (filldir(dirent, "..", 2, filp->f_pos, ino, DT_DIR) == 0)
 857                         filp->f_pos++;
 858         }
 859         mutex_lock(&sysfs_mutex);
 860         for (pos = sysfs_dir_pos(parent_sd, filp->f_pos, pos);
 861              pos;
 862              pos = sysfs_dir_next_pos(parent_sd, filp->f_pos, pos)) {
 863                 const char * name;
 864                 unsigned int type;
 865                 int len, ret;
 866
 867                 name = pos->s_name;
 868                 len = strlen(name);
 869                 ino = pos->s_ino;
 870                 type = dt_type(pos);
 871                 filp->f_pos = ino;
 872                 filp->private_data = sysfs_get(pos);
 873
 874                 mutex_unlock(&sysfs_mutex);
 875                 ret = filldir(dirent, name, len, filp->f_pos, ino, type);
 876                 mutex_lock(&sysfs_mutex);
 877                 if (ret < 0)
 878                         break;
 879         }
 880         mutex_unlock(&sysfs_mutex);
 881         if ((filp->f_pos > 1) && !pos) { /* EOF */
 882                 filp->f_pos = INT_MAX;
 883                 filp->private_data = NULL;
 884         }
 885         return 0;
 886 }
 887
 888
 889 const struct file_operations sysfs_dir_operations = {
 890         .read           = generic_read_dir,
 891         .readdir        = sysfs_readdir,
 892         .release        = sysfs_dir_release,
 893         .llseek         = generic_file_llseek,
 894 };