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