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         atomic_set(&sd->s_event, 1);
  47         INIT_LIST_HEAD(&sd->s_children);
  48         list_add(&sd->s_sibling, &parent_sd->s_children);
  49         sd->s_element = element;
  50
  51         return sd;
  52 }
  53
  54 /*
  55  *
  56  * Return -EEXIST if there is already a sysfs element with the same name for
  57  * the same parent.
  58  *
  59  * called with parent inode's i_mutex held
  60  */
  61 int sysfs_dirent_exist(struct sysfs_dirent *parent_sd,
  62                           const unsigned char *new)
  63 {
  64         struct sysfs_dirent * sd;
  65
  66         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
  67                 if (sd->s_element) {
  68                         const unsigned char *existing = sysfs_get_name(sd);
  69                         if (strcmp(existing, new))
  70                                 continue;
  71                         else
  72                                 return -EEXIST;
  73                 }
  74         }
  75
  76         return 0;
  77 }
  78
  79
  80 int sysfs_make_dirent(struct sysfs_dirent * parent_sd, struct dentry * dentry,
  81                         void * element, umode_t mode, int type)
  82 {
  83         struct sysfs_dirent * sd;
  84
  85         sd = sysfs_new_dirent(parent_sd, element);
  86         if (!sd)
  87                 return -ENOMEM;
  88
  89         sd->s_mode = mode;
  90         sd->s_type = type;
  91         sd->s_dentry = dentry;
  92         if (dentry) {
  93                 dentry->d_fsdata = sysfs_get(sd);
  94                 dentry->d_op = &sysfs_dentry_ops;
  95         }
  96
  97         return 0;
  98 }
  99
 100 static int init_dir(struct inode * inode)
 101 {
 102         inode->i_op = &sysfs_dir_inode_operations;
 103         inode->i_fop = &sysfs_dir_operations;
 104
 105         /* directory inodes start off with i_nlink == 2 (for "." entry) */
 106         inc_nlink(inode);
 107         return 0;
 108 }
 109
 110 static int init_file(struct inode * inode)
 111 {
 112         inode->i_size = PAGE_SIZE;
 113         inode->i_fop = &sysfs_file_operations;
 114         return 0;
 115 }
 116
 117 static int init_symlink(struct inode * inode)
 118 {
 119         inode->i_op = &sysfs_symlink_inode_operations;
 120         return 0;
 121 }
 122
 123 static int create_dir(struct kobject * k, struct dentry * p,
 124                       const char * n, struct dentry ** d)
 125 {
 126         int error;
 127         umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
 128
 129         mutex_lock(&p->d_inode->i_mutex);
 130         *d = lookup_one_len(n, p, strlen(n));
 131         if (!IS_ERR(*d)) {
 132                 if (sysfs_dirent_exist(p->d_fsdata, n))
 133                         error = -EEXIST;
 134                 else
 135                         error = sysfs_make_dirent(p->d_fsdata, *d, k, mode,
 136                                                                 SYSFS_DIR);
 137                 if (!error) {
 138                         error = sysfs_create(*d, mode, init_dir);
 139                         if (!error) {
 140                                 inc_nlink(p->d_inode);
 141                                 (*d)->d_op = &sysfs_dentry_ops;
 142                                 d_rehash(*d);
 143                         }
 144                 }
 145                 if (error && (error != -EEXIST)) {
 146                         struct sysfs_dirent *sd = (*d)->d_fsdata;
 147                         if (sd) {
 148                                 list_del_init(&sd->s_sibling);
 149                                 sysfs_put(sd);
 150                         }
 151                         d_drop(*d);
 152                 }
 153                 dput(*d);
 154         } else
 155                 error = PTR_ERR(*d);
 156         mutex_unlock(&p->d_inode->i_mutex);
 157         return error;
 158 }
 159
 160
 161 int sysfs_create_subdir(struct kobject * k, const char * n, struct dentry ** d)
 162 {
 163         return create_dir(k,k->dentry,n,d);
 164 }
 165
 166 /**
 167  *      sysfs_create_dir - create a directory for an object.
 168  *      @parent:        parent parent object.
 169  *      @kobj:          object we're creating directory for.
 170  */
 171
 172 int sysfs_create_dir(struct kobject * kobj)
 173 {
 174         struct dentry * dentry = NULL;
 175         struct dentry * parent;
 176         int error = 0;
 177
 178         BUG_ON(!kobj);
 179
 180         if (kobj->parent)
 181                 parent = kobj->parent->dentry;
 182         else if (sysfs_mount && sysfs_mount->mnt_sb)
 183                 parent = sysfs_mount->mnt_sb->s_root;
 184         else
 185                 return -EFAULT;
 186
 187         error = create_dir(kobj,parent,kobject_name(kobj),&dentry);
 188         if (!error)
 189                 kobj->dentry = dentry;
 190         return error;
 191 }
 192
 193 /* attaches attribute's sysfs_dirent to the dentry corresponding to the
 194  * attribute file
 195  */
 196 static int sysfs_attach_attr(struct sysfs_dirent * sd, struct dentry * dentry)
 197 {
 198         struct attribute * attr = NULL;
 199         struct bin_attribute * bin_attr = NULL;
 200         int (* init) (struct inode *) = NULL;
 201         int error = 0;
 202
 203         if (sd->s_type & SYSFS_KOBJ_BIN_ATTR) {
 204                 bin_attr = sd->s_element;
 205                 attr = &bin_attr->attr;
 206         } else {
 207                 attr = sd->s_element;
 208                 init = init_file;
 209         }
 210
 211         dentry->d_fsdata = sysfs_get(sd);
 212         sd->s_dentry = dentry;
 213         error = sysfs_create(dentry, (attr->mode & S_IALLUGO) | S_IFREG, init);
 214         if (error) {
 215                 sysfs_put(sd);
 216                 return error;
 217         }
 218
 219         if (bin_attr) {
 220                 dentry->d_inode->i_size = bin_attr->size;
 221                 dentry->d_inode->i_fop = &bin_fops;
 222         }
 223         dentry->d_op = &sysfs_dentry_ops;
 224         d_rehash(dentry);
 225
 226         return 0;
 227 }
 228
 229 static int sysfs_attach_link(struct sysfs_dirent * sd, struct dentry * dentry)
 230 {
 231         int err = 0;
 232
 233         dentry->d_fsdata = sysfs_get(sd);
 234         sd->s_dentry = dentry;
 235         err = sysfs_create(dentry, S_IFLNK|S_IRWXUGO, init_symlink);
 236         if (!err) {
 237                 dentry->d_op = &sysfs_dentry_ops;
 238                 d_rehash(dentry);
 239         } else
 240                 sysfs_put(sd);
 241
 242         return err;
 243 }
 244
 245 static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
 246                                 struct nameidata *nd)
 247 {
 248         struct sysfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
 249         struct sysfs_dirent * sd;
 250         int err = 0;
 251
 252         list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
 253                 if (sd->s_type & SYSFS_NOT_PINNED) {
 254                         const unsigned char * name = sysfs_get_name(sd);
 255
 256                         if (strcmp(name, dentry->d_name.name))
 257                                 continue;
 258
 259                         if (sd->s_type & SYSFS_KOBJ_LINK)
 260                                 err = sysfs_attach_link(sd, dentry);
 261                         else
 262                                 err = sysfs_attach_attr(sd, dentry);
 263                         break;
 264                 }
 265         }
 266
 267         return ERR_PTR(err);
 268 }
 269
 270 struct inode_operations sysfs_dir_inode_operations = {
 271         .lookup         = sysfs_lookup,
 272         .setattr        = sysfs_setattr,
 273 };
 274
 275 static void remove_dir(struct dentry * d)
 276 {
 277         struct dentry * parent = dget(d->d_parent);
 278         struct sysfs_dirent * sd;
 279
 280         mutex_lock(&parent->d_inode->i_mutex);
 281         d_delete(d);
 282         sd = d->d_fsdata;
 283         list_del_init(&sd->s_sibling);
 284         sysfs_put(sd);
 285         if (d->d_inode)
 286                 simple_rmdir(parent->d_inode,d);
 287
 288         pr_debug(" o %s removing done (%d)\n",d->d_name.name,
 289                  atomic_read(&d->d_count));
 290
 291         mutex_unlock(&parent->d_inode->i_mutex);
 292         dput(parent);
 293 }
 294
 295 void sysfs_remove_subdir(struct dentry * d)
 296 {
 297         remove_dir(d);
 298 }
 299
 300
 301 /**
 302  *      sysfs_remove_dir - remove an object's directory.
 303  *      @kobj:  object.
 304  *
 305  *      The only thing special about this is that we remove any files in
 306  *      the directory before we remove the directory, and we've inlined
 307  *      what used to be sysfs_rmdir() below, instead of calling separately.
 308  */
 309
 310 void sysfs_remove_dir(struct kobject * kobj)
 311 {
 312         struct dentry * dentry = dget(kobj->dentry);
 313         struct sysfs_dirent * parent_sd;
 314         struct sysfs_dirent * sd, * tmp;
 315
 316         if (!dentry)
 317                 return;
 318
 319         pr_debug("sysfs %s: removing dir\n",dentry->d_name.name);
 320         mutex_lock(&dentry->d_inode->i_mutex);
 321         parent_sd = dentry->d_fsdata;
 322         list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
 323                 if (!sd->s_element || !(sd->s_type & SYSFS_NOT_PINNED))
 324                         continue;
 325                 list_del_init(&sd->s_sibling);
 326                 sysfs_drop_dentry(sd, dentry);
 327                 sysfs_put(sd);
 328         }
 329         mutex_unlock(&dentry->d_inode->i_mutex);
 330
 331         remove_dir(dentry);
 332         /**
 333          * Drop reference from dget() on entrance.
 334          */
 335         dput(dentry);
 336         kobj->dentry = NULL;
 337 }
 338
 339 int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
 340 {
 341         int error = 0;
 342         struct dentry * new_dentry, * parent;
 343
 344         if (!strcmp(kobject_name(kobj), new_name))
 345                 return -EINVAL;
 346
 347         if (!kobj->parent)
 348                 return -EINVAL;
 349
 350         down_write(&sysfs_rename_sem);
 351         parent = kobj->parent->dentry;
 352
 353         mutex_lock(&parent->d_inode->i_mutex);
 354
 355         new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
 356         if (!IS_ERR(new_dentry)) {
 357                 if (!new_dentry->d_inode) {
 358                         error = kobject_set_name(kobj, "%s", new_name);
 359                         if (!error) {
 360                                 d_add(new_dentry, NULL);
 361                                 d_move(kobj->dentry, new_dentry);
 362                         }
 363                         else
 364                                 d_drop(new_dentry);
 365                 } else
 366                         error = -EEXIST;
 367                 dput(new_dentry);
 368         }
 369         mutex_unlock(&parent->d_inode->i_mutex);
 370         up_write(&sysfs_rename_sem);
 371
 372         return error;
 373 }
 374
 375 int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent)
 376 {
 377         struct dentry *old_parent_dentry, *new_parent_dentry, *new_dentry;
 378         struct sysfs_dirent *new_parent_sd, *sd;
 379         int error;
 380
 381         if (!new_parent)
 382                 return -EINVAL;
 383
 384         old_parent_dentry = kobj->parent ?
 385                 kobj->parent->dentry : sysfs_mount->mnt_sb->s_root;
 386         new_parent_dentry = new_parent->dentry;
 387
 388 again:
 389         mutex_lock(&old_parent_dentry->d_inode->i_mutex);
 390         if (!mutex_trylock(&new_parent_dentry->d_inode->i_mutex)) {
 391                 mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
 392                 goto again;
 393         }
 394
 395         new_parent_sd = new_parent_dentry->d_fsdata;
 396         sd = kobj->dentry->d_fsdata;
 397
 398         new_dentry = lookup_one_len(kobj->name, new_parent_dentry,
 399                                     strlen(kobj->name));
 400         if (IS_ERR(new_dentry)) {
 401                 error = PTR_ERR(new_dentry);
 402                 goto out;
 403         } else
 404                 error = 0;
 405         d_add(new_dentry, NULL);
 406         d_move(kobj->dentry, new_dentry);
 407         dput(new_dentry);
 408
 409         /* Remove from old parent's list and insert into new parent's list. */
 410         list_del_init(&sd->s_sibling);
 411         list_add(&sd->s_sibling, &new_parent_sd->s_children);
 412
 413 out:
 414         mutex_unlock(&new_parent_dentry->d_inode->i_mutex);
 415         mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
 416
 417         return error;
 418 }
 419
 420 static int sysfs_dir_open(struct inode *inode, struct file *file)
 421 {
 422         struct dentry * dentry = file->f_dentry;
 423         struct sysfs_dirent * parent_sd = dentry->d_fsdata;
 424
 425         mutex_lock(&dentry->d_inode->i_mutex);
 426         file->private_data = sysfs_new_dirent(parent_sd, NULL);
 427         mutex_unlock(&dentry->d_inode->i_mutex);
 428
 429         return file->private_data ? 0 : -ENOMEM;
 430
 431 }
 432
 433 static int sysfs_dir_close(struct inode *inode, struct file *file)
 434 {
 435         struct dentry * dentry = file->f_dentry;
 436         struct sysfs_dirent * cursor = file->private_data;
 437
 438         mutex_lock(&dentry->d_inode->i_mutex);
 439         list_del_init(&cursor->s_sibling);
 440         mutex_unlock(&dentry->d_inode->i_mutex);
 441
 442         release_sysfs_dirent(cursor);
 443
 444         return 0;
 445 }
 446
 447 /* Relationship between s_mode and the DT_xxx types */
 448 static inline unsigned char dt_type(struct sysfs_dirent *sd)
 449 {
 450         return (sd->s_mode >> 12) & 15;
 451 }
 452
 453 static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
 454 {
 455         struct dentry *dentry = filp->f_dentry;
 456         struct sysfs_dirent * parent_sd = dentry->d_fsdata;
 457         struct sysfs_dirent *cursor = filp->private_data;
 458         struct list_head *p, *q = &cursor->s_sibling;
 459         ino_t ino;
 460         int i = filp->f_pos;
 461
 462         switch (i) {
 463                 case 0:
 464                         ino = dentry->d_inode->i_ino;
 465                         if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
 466                                 break;
 467                         filp->f_pos++;
 468                         i++;
 469                         /* fallthrough */
 470                 case 1:
 471                         ino = parent_ino(dentry);
 472                         if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
 473                                 break;
 474                         filp->f_pos++;
 475                         i++;
 476                         /* fallthrough */
 477                 default:
 478                         if (filp->f_pos == 2)
 479                                 list_move(q, &parent_sd->s_children);
 480
 481                         for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
 482                                 struct sysfs_dirent *next;
 483                                 const char * name;
 484                                 int len;
 485
 486                                 next = list_entry(p, struct sysfs_dirent,
 487                                                    s_sibling);
 488                                 if (!next->s_element)
 489                                         continue;
 490
 491                                 name = sysfs_get_name(next);
 492                                 len = strlen(name);
 493                                 if (next->s_dentry)
 494                                         ino = next->s_dentry->d_inode->i_ino;
 495                                 else
 496                                         ino = iunique(sysfs_sb, 2);
 497
 498                                 if (filldir(dirent, name, len, filp->f_pos, ino,
 499                                                  dt_type(next)) < 0)
 500                                         return 0;
 501
 502                                 list_move(q, p);
 503                                 p = q;
 504                                 filp->f_pos++;
 505                         }
 506         }
 507         return 0;
 508 }
 509
 510 static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
 511 {
 512         struct dentry * dentry = file->f_dentry;
 513
 514         mutex_lock(&dentry->d_inode->i_mutex);
 515         switch (origin) {
 516                 case 1:
 517                         offset += file->f_pos;
 518                 case 0:
 519                         if (offset >= 0)
 520                                 break;
 521                 default:
 522                         mutex_unlock(&file->f_dentry->d_inode->i_mutex);
 523                         return -EINVAL;
 524         }
 525         if (offset != file->f_pos) {
 526                 file->f_pos = offset;
 527                 if (file->f_pos >= 2) {
 528                         struct sysfs_dirent *sd = dentry->d_fsdata;
 529                         struct sysfs_dirent *cursor = file->private_data;
 530                         struct list_head *p;
 531                         loff_t n = file->f_pos - 2;
 532
 533                         list_del(&cursor->s_sibling);
 534                         p = sd->s_children.next;
 535                         while (n && p != &sd->s_children) {
 536                                 struct sysfs_dirent *next;
 537                                 next = list_entry(p, struct sysfs_dirent,
 538                                                    s_sibling);
 539                                 if (next->s_element)
 540                                         n--;
 541                                 p = p->next;
 542                         }
 543                         list_add_tail(&cursor->s_sibling, p);
 544                 }
 545         }
 546         mutex_unlock(&dentry->d_inode->i_mutex);
 547         return offset;
 548 }
 549
 550 const struct file_operations sysfs_dir_operations = {
 551         .open           = sysfs_dir_open,
 552         .release        = sysfs_dir_close,
 553         .llseek         = sysfs_dir_lseek,
 554         .read           = generic_read_dir,
 555         .readdir        = sysfs_readdir,
 556 };