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