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 "sysfs.h"
  13
  14 DECLARE_RWSEM(sysfs_rename_sem);
  15
  16 static void sysfs_d_iput(struct dentry * dentry, struct inode * inode)
  17 {
  18         struct sysfs_dirent * sd = dentry->d_fsdata;
  19
  20         if (sd) {
  21                 BUG_ON(sd->s_dentry != dentry);
  22                 sd->s_dentry = NULL;
  23                 sysfs_put(sd);
  24         }
  25         iput(inode);
  26 }
  27
  28 static struct dentry_operations sysfs_dentry_ops = {
  29         .d_iput         = sysfs_d_iput,
  30 };
  31
  32 /*
  33  * Allocates a new sysfs_dirent and links it to the parent sysfs_dirent
  34  */
  35 static struct sysfs_dirent * sysfs_new_dirent(struct sysfs_dirent * parent_sd,
  36                                                 void * element)
  37 {
  38         struct sysfs_dirent * sd;
  39
  40         sd = kmem_cache_alloc(sysfs_dir_cachep, GFP_KERNEL);
  41         if (!sd)
  42                 return NULL;
  43
  44         memset(sd, 0, sizeof(*sd));
  45         atomic_set(&sd->s_count, 1);
  46         INIT_LIST_HEAD(&sd->s_children);
  47         list_add(&sd->s_sibling, &parent_sd->s_children);
  48         sd->s_element = element;
  49
  50         return sd;
  51 }
  52
  53 int sysfs_make_dirent(struct sysfs_dirent * parent_sd, struct dentry * dentry,
  54                         void * element, umode_t mode, int type)
  55 {
  56         struct sysfs_dirent * sd;
  57
  58         sd = sysfs_new_dirent(parent_sd, element);
  59         if (!sd)
  60                 return -ENOMEM;
  61
  62         sd->s_mode = mode;
  63         sd->s_type = type;
  64         sd->s_dentry = dentry;
  65         if (dentry) {
  66                 dentry->d_fsdata = sysfs_get(sd);
  67                 dentry->d_op = &sysfs_dentry_ops;
  68         }
  69
  70         return 0;
  71 }
  72
  73 static int init_dir(struct inode * inode)
  74 {
  75         inode->i_op = &sysfs_dir_inode_operations;
  76         inode->i_fop = &sysfs_dir_operations;
  77
  78         /* directory inodes start off with i_nlink == 2 (for "." entry) */
  79         inode->i_nlink++;
  80         return 0;
  81 }
  82
  83 static int init_file(struct inode * inode)
  84 {
  85         inode->i_size = PAGE_SIZE;
  86         inode->i_fop = &sysfs_file_operations;
  87         return 0;
  88 }
  89
  90 static int init_symlink(struct inode * inode)
  91 {
  92         inode->i_op = &sysfs_symlink_inode_operations;
  93         return 0;
  94 }
  95
  96 static int create_dir(struct kobject * k, struct dentry * p,
  97                       const char * n, struct dentry ** d)
  98 {
  99         int error;
 100         umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
 101
 102         mutex_lock(&p->d_inode->i_mutex);
 103         *d = lookup_one_len(n, p, strlen(n));
 104         if (!IS_ERR(*d)) {
 105                 error = sysfs_make_dirent(p->d_fsdata, *d, k, mode, SYSFS_DIR);
 106                 if (!error) {
 107                         error = sysfs_create(*d, mode, init_dir);
 108                         if (!error) {
 109                                 p->d_inode->i_nlink++;
 110                                 (*d)->d_op = &sysfs_dentry_ops;
 111                                 d_rehash(*d);
 112                         }
 113                 }
 114                 if (error && (error != -EEXIST)) {
 115                         struct sysfs_dirent *sd = (*d)->d_fsdata;
 116                         if (sd) {
 117                                 list_del_init(&sd->s_sibling);
 118                                 sysfs_put(sd);
 119                         }
 120                         d_drop(*d);
 121                 }
 122                 dput(*d);
 123         } else
 124                 error = PTR_ERR(*d);
 125         mutex_unlock(&p->d_inode->i_mutex);
 126         return error;
 127 }
 128
 129
 130 int sysfs_create_subdir(struct kobject * k, const char * n, struct dentry ** d)
 131 {
 132         return create_dir(k,k->dentry,n,d);
 133 }
 134
 135 /**
 136  *      sysfs_create_dir - create a directory for an object.
 137  *      @parent:        parent parent object.
 138  *      @kobj:          object we're creating directory for.
 139  */
 140
 141 int sysfs_create_dir(struct kobject * kobj)
 142 {
 143         struct dentry * dentry = NULL;
 144         struct dentry * parent;
 145         int error = 0;
 146
 147         BUG_ON(!kobj);
 148
 149         if (kobj->parent)
 150                 parent = kobj->parent->dentry;
 151         else if (sysfs_mount && sysfs_mount->mnt_sb)
 152                 parent = sysfs_mount->mnt_sb->s_root;
 153         else
 154                 return -EFAULT;
 155
 156         error = create_dir(kobj,parent,kobject_name(kobj),&dentry);
 157         if (!error)
 158                 kobj->dentry = dentry;
 159         return error;
 160 }
 161
 162 /* attaches attribute's sysfs_dirent to the dentry corresponding to the
 163  * attribute file
 164  */
 165 static int sysfs_attach_attr(struct sysfs_dirent * sd, struct dentry * dentry)
 166 {
 167         struct attribute * attr = NULL;
 168         struct bin_attribute * bin_attr = NULL;
 169         int (* init) (struct inode *) = NULL;
 170         int error = 0;
 171
 172         if (sd->s_type & SYSFS_KOBJ_BIN_ATTR) {
 173                 bin_attr = sd->s_element;
 174                 attr = &bin_attr->attr;
 175         } else {
 176                 attr = sd->s_element;
 177                 init = init_file;
 178         }
 179
 180         dentry->d_fsdata = sysfs_get(sd);
 181         sd->s_dentry = dentry;
 182         error = sysfs_create(dentry, (attr->mode & S_IALLUGO) | S_IFREG, init);
 183         if (error) {
 184                 sysfs_put(sd);
 185                 return error;
 186         }
 187
 188         if (bin_attr) {
 189                 dentry->d_inode->i_size = bin_attr->size;
 190                 dentry->d_inode->i_fop = &bin_fops;
 191         }
 192         dentry->d_op = &sysfs_dentry_ops;
 193         d_rehash(dentry);
 194
 195         return 0;
 196 }
 197
 198 static int sysfs_attach_link(struct sysfs_dirent * sd, struct dentry * dentry)
 199 {
 200         int err = 0;
 201
 202         dentry->d_fsdata = sysfs_get(sd);
 203         sd->s_dentry = dentry;
 204         err = sysfs_create(dentry, S_IFLNK|S_IRWXUGO, init_symlink);
 205         if (!err) {
 206                 dentry->d_op = &sysfs_dentry_ops;
 207                 d_rehash(dentry);
 208         } else
 209                 sysfs_put(sd);
 210
 211         return err;
 212 }
 213
 214 static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
 215                                 struct nameidata *nd)
 216 {
 217         struct sysfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
 218         struct sysfs_dirent * sd;
 219         int err = 0;
 220
 221         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 222                 if (sd->s_type & SYSFS_NOT_PINNED) {
 223                         const unsigned char * name = sysfs_get_name(sd);
 224
 225                         if (strcmp(name, dentry->d_name.name))
 226                                 continue;
 227
 228                         if (sd->s_type & SYSFS_KOBJ_LINK)
 229                                 err = sysfs_attach_link(sd, dentry);
 230                         else
 231                                 err = sysfs_attach_attr(sd, dentry);
 232                         break;
 233                 }
 234         }
 235
 236         return ERR_PTR(err);
 237 }
 238
 239 struct inode_operations sysfs_dir_inode_operations = {
 240         .lookup         = sysfs_lookup,
 241         .setattr        = sysfs_setattr,
 242 };
 243
 244 static void remove_dir(struct dentry * d)
 245 {
 246         struct dentry * parent = dget(d->d_parent);
 247         struct sysfs_dirent * sd;
 248
 249         mutex_lock(&parent->d_inode->i_mutex);
 250         d_delete(d);
 251         sd = d->d_fsdata;
 252         list_del_init(&sd->s_sibling);
 253         sysfs_put(sd);
 254         if (d->d_inode)
 255                 simple_rmdir(parent->d_inode,d);
 256
 257         pr_debug(" o %s removing done (%d)\n",d->d_name.name,
 258                  atomic_read(&d->d_count));
 259
 260         mutex_unlock(&parent->d_inode->i_mutex);
 261         dput(parent);
 262 }
 263
 264 void sysfs_remove_subdir(struct dentry * d)
 265 {
 266         remove_dir(d);
 267 }
 268
 269
 270 /**
 271  *      sysfs_remove_dir - remove an object's directory.
 272  *      @kobj:  object.
 273  *
 274  *      The only thing special about this is that we remove any files in
 275  *      the directory before we remove the directory, and we've inlined
 276  *      what used to be sysfs_rmdir() below, instead of calling separately.
 277  */
 278
 279 void sysfs_remove_dir(struct kobject * kobj)
 280 {
 281         struct dentry * dentry = dget(kobj->dentry);
 282         struct sysfs_dirent * parent_sd;
 283         struct sysfs_dirent * sd, * tmp;
 284
 285         if (!dentry)
 286                 return;
 287
 288         pr_debug("sysfs %s: removing dir\n",dentry->d_name.name);
 289         mutex_lock(&dentry->d_inode->i_mutex);
 290         parent_sd = dentry->d_fsdata;
 291         list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
 292                 if (!sd->s_element || !(sd->s_type & SYSFS_NOT_PINNED))
 293                         continue;
 294                 list_del_init(&sd->s_sibling);
 295                 sysfs_drop_dentry(sd, dentry);
 296                 sysfs_put(sd);
 297         }
 298         mutex_unlock(&dentry->d_inode->i_mutex);
 299
 300         remove_dir(dentry);
 301         /**
 302          * Drop reference from dget() on entrance.
 303          */
 304         dput(dentry);
 305         kobj->dentry = NULL;
 306 }
 307
 308 int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
 309 {
 310         int error = 0;
 311         struct dentry * new_dentry, * parent;
 312
 313         if (!strcmp(kobject_name(kobj), new_name))
 314                 return -EINVAL;
 315
 316         if (!kobj->parent)
 317                 return -EINVAL;
 318
 319         down_write(&sysfs_rename_sem);
 320         parent = kobj->parent->dentry;
 321
 322         mutex_lock(&parent->d_inode->i_mutex);
 323
 324         new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
 325         if (!IS_ERR(new_dentry)) {
 326                 if (!new_dentry->d_inode) {
 327                         error = kobject_set_name(kobj, "%s", new_name);
 328                         if (!error) {
 329                                 d_add(new_dentry, NULL);
 330                                 d_move(kobj->dentry, new_dentry);
 331                         }
 332                         else
 333                                 d_drop(new_dentry);
 334                 } else
 335                         error = -EEXIST;
 336                 dput(new_dentry);
 337         }
 338         mutex_unlock(&parent->d_inode->i_mutex);
 339         up_write(&sysfs_rename_sem);
 340
 341         return error;
 342 }
 343
 344 static int sysfs_dir_open(struct inode *inode, struct file *file)
 345 {
 346         struct dentry * dentry = file->f_dentry;
 347         struct sysfs_dirent * parent_sd = dentry->d_fsdata;
 348
 349         mutex_lock(&dentry->d_inode->i_mutex);
 350         file->private_data = sysfs_new_dirent(parent_sd, NULL);
 351         mutex_unlock(&dentry->d_inode->i_mutex);
 352
 353         return file->private_data ? 0 : -ENOMEM;
 354
 355 }
 356
 357 static int sysfs_dir_close(struct inode *inode, struct file *file)
 358 {
 359         struct dentry * dentry = file->f_dentry;
 360         struct sysfs_dirent * cursor = file->private_data;
 361
 362         mutex_lock(&dentry->d_inode->i_mutex);
 363         list_del_init(&cursor->s_sibling);
 364         mutex_unlock(&dentry->d_inode->i_mutex);
 365
 366         release_sysfs_dirent(cursor);
 367
 368         return 0;
 369 }
 370
 371 /* Relationship between s_mode and the DT_xxx types */
 372 static inline unsigned char dt_type(struct sysfs_dirent *sd)
 373 {
 374         return (sd->s_mode >> 12) & 15;
 375 }
 376
 377 static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
 378 {
 379         struct dentry *dentry = filp->f_dentry;
 380         struct sysfs_dirent * parent_sd = dentry->d_fsdata;
 381         struct sysfs_dirent *cursor = filp->private_data;
 382         struct list_head *p, *q = &cursor->s_sibling;
 383         ino_t ino;
 384         int i = filp->f_pos;
 385
 386         switch (i) {
 387                 case 0:
 388                         ino = dentry->d_inode->i_ino;
 389                         if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
 390                                 break;
 391                         filp->f_pos++;
 392                         i++;
 393                         /* fallthrough */
 394                 case 1:
 395                         ino = parent_ino(dentry);
 396                         if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
 397                                 break;
 398                         filp->f_pos++;
 399                         i++;
 400                         /* fallthrough */
 401                 default:
 402                         if (filp->f_pos == 2) {
 403                                 list_del(q);
 404                                 list_add(q, &parent_sd->s_children);
 405                         }
 406                         for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
 407                                 struct sysfs_dirent *next;
 408                                 const char * name;
 409                                 int len;
 410
 411                                 next = list_entry(p, struct sysfs_dirent,
 412                                                    s_sibling);
 413                                 if (!next->s_element)
 414                                         continue;
 415
 416                                 name = sysfs_get_name(next);
 417                                 len = strlen(name);
 418                                 if (next->s_dentry)
 419                                         ino = next->s_dentry->d_inode->i_ino;
 420                                 else
 421                                         ino = iunique(sysfs_sb, 2);
 422
 423                                 if (filldir(dirent, name, len, filp->f_pos, ino,
 424                                                  dt_type(next)) < 0)
 425                                         return 0;
 426
 427                                 list_del(q);
 428                                 list_add(q, p);
 429                                 p = q;
 430                                 filp->f_pos++;
 431                         }
 432         }
 433         return 0;
 434 }
 435
 436 static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
 437 {
 438         struct dentry * dentry = file->f_dentry;
 439
 440         mutex_lock(&dentry->d_inode->i_mutex);
 441         switch (origin) {
 442                 case 1:
 443                         offset += file->f_pos;
 444                 case 0:
 445                         if (offset >= 0)
 446                                 break;
 447                 default:
 448                         mutex_unlock(&file->f_dentry->d_inode->i_mutex);
 449                         return -EINVAL;
 450         }
 451         if (offset != file->f_pos) {
 452                 file->f_pos = offset;
 453                 if (file->f_pos >= 2) {
 454                         struct sysfs_dirent *sd = dentry->d_fsdata;
 455                         struct sysfs_dirent *cursor = file->private_data;
 456                         struct list_head *p;
 457                         loff_t n = file->f_pos - 2;
 458
 459                         list_del(&cursor->s_sibling);
 460                         p = sd->s_children.next;
 461                         while (n && p != &sd->s_children) {
 462                                 struct sysfs_dirent *next;
 463                                 next = list_entry(p, struct sysfs_dirent,
 464                                                    s_sibling);
 465                                 if (next->s_element)
 466                                         n--;
 467                                 p = p->next;
 468                         }
 469                         list_add_tail(&cursor->s_sibling, p);
 470                 }
 471         }
 472         mutex_unlock(&dentry->d_inode->i_mutex);
 473         return offset;
 474 }
 475
 476 struct file_operations sysfs_dir_operations = {
 477         .open           = sysfs_dir_open,
 478         .release        = sysfs_dir_close,
 479         .llseek         = sysfs_dir_lseek,
 480         .read           = generic_read_dir,
 481         .readdir        = sysfs_readdir,
 482 };
 483
 484 EXPORT_SYMBOL_GPL(sysfs_create_dir);
 485 EXPORT_SYMBOL_GPL(sysfs_remove_dir);
 486 EXPORT_SYMBOL_GPL(sysfs_rename_dir);