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