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 /**
  54  *
  55  * Return -EEXIST if there is already a sysfs element with the same name for
  56  * the same parent.
  57  *
  58  * called with parent inode's i_mutex held
  59  */
  60 int sysfs_dirent_exist(struct sysfs_dirent *parent_sd,
  61                           const unsigned char *new)
  62 {
  63         struct sysfs_dirent * sd;
  64
  65         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
  66                 if (sd->s_element) {
  67                         const unsigned char *existing = sysfs_get_name(sd);
  68                         if (strcmp(existing, new))
  69                                 continue;
  70                         else
  71                                 return -EEXIST;
  72                 }
  73         }
  74
  75         return 0;
  76 }
  77
  78
  79 int sysfs_make_dirent(struct sysfs_dirent * parent_sd, struct dentry * dentry,
  80                         void * element, umode_t mode, int type)
  81 {
  82         struct sysfs_dirent * sd;
  83
  84         sd = sysfs_new_dirent(parent_sd, element);
  85         if (!sd)
  86                 return -ENOMEM;
  87
  88         sd->s_mode = mode;
  89         sd->s_type = type;
  90         sd->s_dentry = dentry;
  91         if (dentry) {
  92                 dentry->d_fsdata = sysfs_get(sd);
  93                 dentry->d_op = &sysfs_dentry_ops;
  94         }
  95
  96         return 0;
  97 }
  98
  99 static int init_dir(struct inode * inode)
 100 {
 101         inode->i_op = &sysfs_dir_inode_operations;
 102         inode->i_fop = &sysfs_dir_operations;
 103
 104         /* directory inodes start off with i_nlink == 2 (for "." entry) */
 105         inode->i_nlink++;
 106         return 0;
 107 }
 108
 109 static int init_file(struct inode * inode)
 110 {
 111         inode->i_size = PAGE_SIZE;
 112         inode->i_fop = &sysfs_file_operations;
 113         return 0;
 114 }
 115
 116 static int init_symlink(struct inode * inode)
 117 {
 118         inode->i_op = &sysfs_symlink_inode_operations;
 119         return 0;
 120 }
 121
 122 static int create_dir(struct kobject * k, struct dentry * p,
 123                       const char * n, struct dentry ** d)
 124 {
 125         int error;
 126         umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
 127
 128         mutex_lock(&p->d_inode->i_mutex);
 129         *d = lookup_one_len(n, p, strlen(n));
 130         if (!IS_ERR(*d)) {
 131                 if (sysfs_dirent_exist(p->d_fsdata, n))
 132                         error = -EEXIST;
 133                 else
 134                         error = sysfs_make_dirent(p->d_fsdata, *d, k, mode,
 135                                                                 SYSFS_DIR);
 136                 if (!error) {
 137                         error = sysfs_create(*d, mode, init_dir);
 138                         if (!error) {
 139                                 p->d_inode->i_nlink++;
 140                                 (*d)->d_op = &sysfs_dentry_ops;
 141                                 d_rehash(*d);
 142                         }
 143                 }
 144                 if (error && (error != -EEXIST)) {
 145                         struct sysfs_dirent *sd = (*d)->d_fsdata;
 146                         if (sd) {
 147                                 list_del_init(&sd->s_sibling);
 148                                 sysfs_put(sd);
 149                         }
 150                         d_drop(*d);
 151                 }
 152                 dput(*d);
 153         } else
 154                 error = PTR_ERR(*d);
 155         mutex_unlock(&p->d_inode->i_mutex);
 156         return error;
 157 }
 158
 159
 160 int sysfs_create_subdir(struct kobject * k, const char * n, struct dentry ** d)
 161 {
 162         return create_dir(k,k->dentry,n,d);
 163 }
 164
 165 /**
 166  *      sysfs_create_dir - create a directory for an object.
 167  *      @parent:        parent parent object.
 168  *      @kobj:          object we're creating directory for.
 169  */
 170
 171 int sysfs_create_dir(struct kobject * kobj)
 172 {
 173         struct dentry * dentry = NULL;
 174         struct dentry * parent;
 175         int error = 0;
 176
 177         BUG_ON(!kobj);
 178
 179         if (kobj->parent)
 180                 parent = kobj->parent->dentry;
 181         else if (sysfs_mount && sysfs_mount->mnt_sb)
 182                 parent = sysfs_mount->mnt_sb->s_root;
 183         else
 184                 return -EFAULT;
 185
 186         error = create_dir(kobj,parent,kobject_name(kobj),&dentry);
 187         if (!error)
 188                 kobj->dentry = dentry;
 189         return error;
 190 }
 191
 192 /* attaches attribute's sysfs_dirent to the dentry corresponding to the
 193  * attribute file
 194  */
 195 static int sysfs_attach_attr(struct sysfs_dirent * sd, struct dentry * dentry)
 196 {
 197         struct attribute * attr = NULL;
 198         struct bin_attribute * bin_attr = NULL;
 199         int (* init) (struct inode *) = NULL;
 200         int error = 0;
 201
 202         if (sd->s_type & SYSFS_KOBJ_BIN_ATTR) {
 203                 bin_attr = sd->s_element;
 204                 attr = &bin_attr->attr;
 205         } else {
 206                 attr = sd->s_element;
 207                 init = init_file;
 208         }
 209
 210         dentry->d_fsdata = sysfs_get(sd);
 211         sd->s_dentry = dentry;
 212         error = sysfs_create(dentry, (attr->mode & S_IALLUGO) | S_IFREG, init);
 213         if (error) {
 214                 sysfs_put(sd);
 215                 return error;
 216         }
 217
 218         if (bin_attr) {
 219                 dentry->d_inode->i_size = bin_attr->size;
 220                 dentry->d_inode->i_fop = &bin_fops;
 221         }
 222         dentry->d_op = &sysfs_dentry_ops;
 223         d_rehash(dentry);
 224
 225         return 0;
 226 }
 227
 228 static int sysfs_attach_link(struct sysfs_dirent * sd, struct dentry * dentry)
 229 {
 230         int err = 0;
 231
 232         dentry->d_fsdata = sysfs_get(sd);
 233         sd->s_dentry = dentry;
 234         err = sysfs_create(dentry, S_IFLNK|S_IRWXUGO, init_symlink);
 235         if (!err) {
 236                 dentry->d_op = &sysfs_dentry_ops;
 237                 d_rehash(dentry);
 238         } else
 239                 sysfs_put(sd);
 240
 241         return err;
 242 }
 243
 244 static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
 245                                 struct nameidata *nd)
 246 {
 247         struct sysfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
 248         struct sysfs_dirent * sd;
 249         int err = 0;
 250
 251         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 252                 if (sd->s_type & SYSFS_NOT_PINNED) {
 253                         const unsigned char * name = sysfs_get_name(sd);
 254
 255                         if (strcmp(name, dentry->d_name.name))
 256                                 continue;
 257
 258                         if (sd->s_type & SYSFS_KOBJ_LINK)
 259                                 err = sysfs_attach_link(sd, dentry);
 260                         else
 261                                 err = sysfs_attach_attr(sd, dentry);
 262                         break;
 263                 }
 264         }
 265
 266         return ERR_PTR(err);
 267 }
 268
 269 struct inode_operations sysfs_dir_inode_operations = {
 270         .lookup         = sysfs_lookup,
 271         .setattr        = sysfs_setattr,
 272 };
 273
 274 static void remove_dir(struct dentry * d)
 275 {
 276         struct dentry * parent = dget(d->d_parent);
 277         struct sysfs_dirent * sd;
 278
 279         mutex_lock(&parent->d_inode->i_mutex);
 280         d_delete(d);
 281         sd = d->d_fsdata;
 282         list_del_init(&sd->s_sibling);
 283         sysfs_put(sd);
 284         if (d->d_inode)
 285                 simple_rmdir(parent->d_inode,d);
 286
 287         pr_debug(" o %s removing done (%d)\n",d->d_name.name,
 288                  atomic_read(&d->d_count));
 289
 290         mutex_unlock(&parent->d_inode->i_mutex);
 291         dput(parent);
 292 }
 293
 294 void sysfs_remove_subdir(struct dentry * d)
 295 {
 296         remove_dir(d);
 297 }
 298
 299
 300 /**
 301  *      sysfs_remove_dir - remove an object's directory.
 302  *      @kobj:  object.
 303  *
 304  *      The only thing special about this is that we remove any files in
 305  *      the directory before we remove the directory, and we've inlined
 306  *      what used to be sysfs_rmdir() below, instead of calling separately.
 307  */
 308
 309 void sysfs_remove_dir(struct kobject * kobj)
 310 {
 311         struct dentry * dentry = dget(kobj->dentry);
 312         struct sysfs_dirent * parent_sd;
 313         struct sysfs_dirent * sd, * tmp;
 314
 315         if (!dentry)
 316                 return;
 317
 318         pr_debug("sysfs %s: removing dir\n",dentry->d_name.name);
 319         mutex_lock(&dentry->d_inode->i_mutex);
 320         parent_sd = dentry->d_fsdata;
 321         list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
 322                 if (!sd->s_element || !(sd->s_type & SYSFS_NOT_PINNED))
 323                         continue;
 324                 list_del_init(&sd->s_sibling);
 325                 sysfs_drop_dentry(sd, dentry);
 326                 sysfs_put(sd);
 327         }
 328         mutex_unlock(&dentry->d_inode->i_mutex);
 329
 330         remove_dir(dentry);
 331         /**
 332          * Drop reference from dget() on entrance.
 333          */
 334         dput(dentry);
 335         kobj->dentry = NULL;
 336 }
 337
 338 int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
 339 {
 340         int error = 0;
 341         struct dentry * new_dentry, * parent;
 342
 343         if (!strcmp(kobject_name(kobj), new_name))
 344                 return -EINVAL;
 345
 346         if (!kobj->parent)
 347                 return -EINVAL;
 348
 349         down_write(&sysfs_rename_sem);
 350         parent = kobj->parent->dentry;
 351
 352         mutex_lock(&parent->d_inode->i_mutex);
 353
 354         new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
 355         if (!IS_ERR(new_dentry)) {
 356                 if (!new_dentry->d_inode) {
 357                         error = kobject_set_name(kobj, "%s", new_name);
 358                         if (!error) {
 359                                 d_add(new_dentry, NULL);
 360                                 d_move(kobj->dentry, new_dentry);
 361                         }
 362                         else
 363                                 d_drop(new_dentry);
 364                 } else
 365                         error = -EEXIST;
 366                 dput(new_dentry);
 367         }
 368         mutex_unlock(&parent->d_inode->i_mutex);
 369         up_write(&sysfs_rename_sem);
 370
 371         return error;
 372 }
 373
 374 static int sysfs_dir_open(struct inode *inode, struct file *file)
 375 {
 376         struct dentry * dentry = file->f_dentry;
 377         struct sysfs_dirent * parent_sd = dentry->d_fsdata;
 378
 379         mutex_lock(&dentry->d_inode->i_mutex);
 380         file->private_data = sysfs_new_dirent(parent_sd, NULL);
 381         mutex_unlock(&dentry->d_inode->i_mutex);
 382
 383         return file->private_data ? 0 : -ENOMEM;
 384
 385 }
 386
 387 static int sysfs_dir_close(struct inode *inode, struct file *file)
 388 {
 389         struct dentry * dentry = file->f_dentry;
 390         struct sysfs_dirent * cursor = file->private_data;
 391
 392         mutex_lock(&dentry->d_inode->i_mutex);
 393         list_del_init(&cursor->s_sibling);
 394         mutex_unlock(&dentry->d_inode->i_mutex);
 395
 396         release_sysfs_dirent(cursor);
 397
 398         return 0;
 399 }
 400
 401 /* Relationship between s_mode and the DT_xxx types */
 402 static inline unsigned char dt_type(struct sysfs_dirent *sd)
 403 {
 404         return (sd->s_mode >> 12) & 15;
 405 }
 406
 407 static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
 408 {
 409         struct dentry *dentry = filp->f_dentry;
 410         struct sysfs_dirent * parent_sd = dentry->d_fsdata;
 411         struct sysfs_dirent *cursor = filp->private_data;
 412         struct list_head *p, *q = &cursor->s_sibling;
 413         ino_t ino;
 414         int i = filp->f_pos;
 415
 416         switch (i) {
 417                 case 0:
 418                         ino = dentry->d_inode->i_ino;
 419                         if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
 420                                 break;
 421                         filp->f_pos++;
 422                         i++;
 423                         /* fallthrough */
 424                 case 1:
 425                         ino = parent_ino(dentry);
 426                         if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
 427                                 break;
 428                         filp->f_pos++;
 429                         i++;
 430                         /* fallthrough */
 431                 default:
 432                         if (filp->f_pos == 2) {
 433                                 list_del(q);
 434                                 list_add(q, &parent_sd->s_children);
 435                         }
 436                         for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
 437                                 struct sysfs_dirent *next;
 438                                 const char * name;
 439                                 int len;
 440
 441                                 next = list_entry(p, struct sysfs_dirent,
 442                                                    s_sibling);
 443                                 if (!next->s_element)
 444                                         continue;
 445
 446                                 name = sysfs_get_name(next);
 447                                 len = strlen(name);
 448                                 if (next->s_dentry)
 449                                         ino = next->s_dentry->d_inode->i_ino;
 450                                 else
 451                                         ino = iunique(sysfs_sb, 2);
 452
 453                                 if (filldir(dirent, name, len, filp->f_pos, ino,
 454                                                  dt_type(next)) < 0)
 455                                         return 0;
 456
 457                                 list_del(q);
 458                                 list_add(q, p);
 459                                 p = q;
 460                                 filp->f_pos++;
 461                         }
 462         }
 463         return 0;
 464 }
 465
 466 static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
 467 {
 468         struct dentry * dentry = file->f_dentry;
 469
 470         mutex_lock(&dentry->d_inode->i_mutex);
 471         switch (origin) {
 472                 case 1:
 473                         offset += file->f_pos;
 474                 case 0:
 475                         if (offset >= 0)
 476                                 break;
 477                 default:
 478                         mutex_unlock(&file->f_dentry->d_inode->i_mutex);
 479                         return -EINVAL;
 480         }
 481         if (offset != file->f_pos) {
 482                 file->f_pos = offset;
 483                 if (file->f_pos >= 2) {
 484                         struct sysfs_dirent *sd = dentry->d_fsdata;
 485                         struct sysfs_dirent *cursor = file->private_data;
 486                         struct list_head *p;
 487                         loff_t n = file->f_pos - 2;
 488
 489                         list_del(&cursor->s_sibling);
 490                         p = sd->s_children.next;
 491                         while (n && p != &sd->s_children) {
 492                                 struct sysfs_dirent *next;
 493                                 next = list_entry(p, struct sysfs_dirent,
 494                                                    s_sibling);
 495                                 if (next->s_element)
 496                                         n--;
 497                                 p = p->next;
 498                         }
 499                         list_add_tail(&cursor->s_sibling, p);
 500                 }
 501         }
 502         mutex_unlock(&dentry->d_inode->i_mutex);
 503         return offset;
 504 }
 505
 506 const struct file_operations sysfs_dir_operations = {
 507         .open           = sysfs_dir_open,
 508         .release        = sysfs_dir_close,
 509         .llseek         = sysfs_dir_lseek,
 510         .read           = generic_read_dir,
 511         .readdir        = sysfs_readdir,
 512 };