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