| 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 <linux/idr.h> |
| 13 | #include <linux/completion.h> |
| 14 | #include <linux/mutex.h> |
| 15 | #include "sysfs.h" |
| 16 | |
| 17 | DEFINE_MUTEX(sysfs_mutex); |
| 18 | spinlock_t sysfs_assoc_lock = SPIN_LOCK_UNLOCKED; |
| 19 | |
| 20 | static spinlock_t sysfs_ino_lock = SPIN_LOCK_UNLOCKED; |
| 21 | static DEFINE_IDA(sysfs_ino_ida); |
| 22 | |
| 23 | /** |
| 24 | * sysfs_link_sibling - link sysfs_dirent into sibling list |
| 25 | * @sd: sysfs_dirent of interest |
| 26 | * |
| 27 | * Link @sd into its sibling list which starts from |
| 28 | * sd->s_parent->s_children. |
| 29 | * |
| 30 | * Locking: |
| 31 | * mutex_lock(sysfs_mutex) |
| 32 | */ |
| 33 | void sysfs_link_sibling(struct sysfs_dirent *sd) |
| 34 | { |
| 35 | struct sysfs_dirent *parent_sd = sd->s_parent; |
| 36 | |
| 37 | BUG_ON(sd->s_sibling); |
| 38 | sd->s_sibling = parent_sd->s_children; |
| 39 | parent_sd->s_children = sd; |
| 40 | } |
| 41 | |
| 42 | /** |
| 43 | * sysfs_unlink_sibling - unlink sysfs_dirent from sibling list |
| 44 | * @sd: sysfs_dirent of interest |
| 45 | * |
| 46 | * Unlink @sd from its sibling list which starts from |
| 47 | * sd->s_parent->s_children. |
| 48 | * |
| 49 | * Locking: |
| 50 | * mutex_lock(sysfs_mutex) |
| 51 | */ |
| 52 | void sysfs_unlink_sibling(struct sysfs_dirent *sd) |
| 53 | { |
| 54 | struct sysfs_dirent **pos; |
| 55 | |
| 56 | for (pos = &sd->s_parent->s_children; *pos; pos = &(*pos)->s_sibling) { |
| 57 | if (*pos == sd) { |
| 58 | *pos = sd->s_sibling; |
| 59 | sd->s_sibling = NULL; |
| 60 | break; |
| 61 | } |
| 62 | } |
| 63 | } |
| 64 | |
| 65 | /** |
| 66 | * sysfs_get_dentry - get dentry for the given sysfs_dirent |
| 67 | * @sd: sysfs_dirent of interest |
| 68 | * |
| 69 | * Get dentry for @sd. Dentry is looked up if currently not |
| 70 | * present. This function climbs sysfs_dirent tree till it |
| 71 | * reaches a sysfs_dirent with valid dentry attached and descends |
| 72 | * down from there looking up dentry for each step. |
| 73 | * |
| 74 | * LOCKING: |
| 75 | * Kernel thread context (may sleep) |
| 76 | * |
| 77 | * RETURNS: |
| 78 | * Pointer to found dentry on success, ERR_PTR() value on error. |
| 79 | */ |
| 80 | struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd) |
| 81 | { |
| 82 | struct sysfs_dirent *cur; |
| 83 | struct dentry *parent_dentry, *dentry; |
| 84 | int i, depth; |
| 85 | |
| 86 | /* Find the first parent which has valid s_dentry and get the |
| 87 | * dentry. |
| 88 | */ |
| 89 | mutex_lock(&sysfs_mutex); |
| 90 | restart0: |
| 91 | spin_lock(&sysfs_assoc_lock); |
| 92 | restart1: |
| 93 | spin_lock(&dcache_lock); |
| 94 | |
| 95 | dentry = NULL; |
| 96 | depth = 0; |
| 97 | cur = sd; |
| 98 | while (!cur->s_dentry || !cur->s_dentry->d_inode) { |
| 99 | if (cur->s_flags & SYSFS_FLAG_REMOVED) { |
| 100 | dentry = ERR_PTR(-ENOENT); |
| 101 | depth = 0; |
| 102 | break; |
| 103 | } |
| 104 | cur = cur->s_parent; |
| 105 | depth++; |
| 106 | } |
| 107 | if (!IS_ERR(dentry)) |
| 108 | dentry = dget_locked(cur->s_dentry); |
| 109 | |
| 110 | spin_unlock(&dcache_lock); |
| 111 | spin_unlock(&sysfs_assoc_lock); |
| 112 | |
| 113 | /* from the found dentry, look up depth times */ |
| 114 | while (depth--) { |
| 115 | /* find and get depth'th ancestor */ |
| 116 | for (cur = sd, i = 0; cur && i < depth; i++) |
| 117 | cur = cur->s_parent; |
| 118 | |
| 119 | /* This can happen if tree structure was modified due |
| 120 | * to move/rename. Restart. |
| 121 | */ |
| 122 | if (i != depth) { |
| 123 | dput(dentry); |
| 124 | goto restart0; |
| 125 | } |
| 126 | |
| 127 | sysfs_get(cur); |
| 128 | |
| 129 | mutex_unlock(&sysfs_mutex); |
| 130 | |
| 131 | /* look it up */ |
| 132 | parent_dentry = dentry; |
| 133 | dentry = lookup_one_len_kern(cur->s_name, parent_dentry, |
| 134 | strlen(cur->s_name)); |
| 135 | dput(parent_dentry); |
| 136 | |
| 137 | if (IS_ERR(dentry)) { |
| 138 | sysfs_put(cur); |
| 139 | return dentry; |
| 140 | } |
| 141 | |
| 142 | mutex_lock(&sysfs_mutex); |
| 143 | spin_lock(&sysfs_assoc_lock); |
| 144 | |
| 145 | /* This, again, can happen if tree structure has |
| 146 | * changed and we looked up the wrong thing. Restart. |
| 147 | */ |
| 148 | if (cur->s_dentry != dentry) { |
| 149 | dput(dentry); |
| 150 | sysfs_put(cur); |
| 151 | goto restart1; |
| 152 | } |
| 153 | |
| 154 | spin_unlock(&sysfs_assoc_lock); |
| 155 | |
| 156 | sysfs_put(cur); |
| 157 | } |
| 158 | |
| 159 | mutex_unlock(&sysfs_mutex); |
| 160 | return dentry; |
| 161 | } |
| 162 | |
| 163 | /** |
| 164 | * sysfs_get_active - get an active reference to sysfs_dirent |
| 165 | * @sd: sysfs_dirent to get an active reference to |
| 166 | * |
| 167 | * Get an active reference of @sd. This function is noop if @sd |
| 168 | * is NULL. |
| 169 | * |
| 170 | * RETURNS: |
| 171 | * Pointer to @sd on success, NULL on failure. |
| 172 | */ |
| 173 | struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd) |
| 174 | { |
| 175 | if (unlikely(!sd)) |
| 176 | return NULL; |
| 177 | |
| 178 | while (1) { |
| 179 | int v, t; |
| 180 | |
| 181 | v = atomic_read(&sd->s_active); |
| 182 | if (unlikely(v < 0)) |
| 183 | return NULL; |
| 184 | |
| 185 | t = atomic_cmpxchg(&sd->s_active, v, v + 1); |
| 186 | if (likely(t == v)) |
| 187 | return sd; |
| 188 | if (t < 0) |
| 189 | return NULL; |
| 190 | |
| 191 | cpu_relax(); |
| 192 | } |
| 193 | } |
| 194 | |
| 195 | /** |
| 196 | * sysfs_put_active - put an active reference to sysfs_dirent |
| 197 | * @sd: sysfs_dirent to put an active reference to |
| 198 | * |
| 199 | * Put an active reference to @sd. This function is noop if @sd |
| 200 | * is NULL. |
| 201 | */ |
| 202 | void sysfs_put_active(struct sysfs_dirent *sd) |
| 203 | { |
| 204 | struct completion *cmpl; |
| 205 | int v; |
| 206 | |
| 207 | if (unlikely(!sd)) |
| 208 | return; |
| 209 | |
| 210 | v = atomic_dec_return(&sd->s_active); |
| 211 | if (likely(v != SD_DEACTIVATED_BIAS)) |
| 212 | return; |
| 213 | |
| 214 | /* atomic_dec_return() is a mb(), we'll always see the updated |
| 215 | * sd->s_sibling. |
| 216 | */ |
| 217 | cmpl = (void *)sd->s_sibling; |
| 218 | complete(cmpl); |
| 219 | } |
| 220 | |
| 221 | /** |
| 222 | * sysfs_get_active_two - get active references to sysfs_dirent and parent |
| 223 | * @sd: sysfs_dirent of interest |
| 224 | * |
| 225 | * Get active reference to @sd and its parent. Parent's active |
| 226 | * reference is grabbed first. This function is noop if @sd is |
| 227 | * NULL. |
| 228 | * |
| 229 | * RETURNS: |
| 230 | * Pointer to @sd on success, NULL on failure. |
| 231 | */ |
| 232 | struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd) |
| 233 | { |
| 234 | if (sd) { |
| 235 | if (sd->s_parent && unlikely(!sysfs_get_active(sd->s_parent))) |
| 236 | return NULL; |
| 237 | if (unlikely(!sysfs_get_active(sd))) { |
| 238 | sysfs_put_active(sd->s_parent); |
| 239 | return NULL; |
| 240 | } |
| 241 | } |
| 242 | return sd; |
| 243 | } |
| 244 | |
| 245 | /** |
| 246 | * sysfs_put_active_two - put active references to sysfs_dirent and parent |
| 247 | * @sd: sysfs_dirent of interest |
| 248 | * |
| 249 | * Put active references to @sd and its parent. This function is |
| 250 | * noop if @sd is NULL. |
| 251 | */ |
| 252 | void sysfs_put_active_two(struct sysfs_dirent *sd) |
| 253 | { |
| 254 | if (sd) { |
| 255 | sysfs_put_active(sd); |
| 256 | sysfs_put_active(sd->s_parent); |
| 257 | } |
| 258 | } |
| 259 | |
| 260 | /** |
| 261 | * sysfs_deactivate - deactivate sysfs_dirent |
| 262 | * @sd: sysfs_dirent to deactivate |
| 263 | * |
| 264 | * Deny new active references and drain existing ones. |
| 265 | */ |
| 266 | static void sysfs_deactivate(struct sysfs_dirent *sd) |
| 267 | { |
| 268 | DECLARE_COMPLETION_ONSTACK(wait); |
| 269 | int v; |
| 270 | |
| 271 | BUG_ON(sd->s_sibling || !(sd->s_flags & SYSFS_FLAG_REMOVED)); |
| 272 | sd->s_sibling = (void *)&wait; |
| 273 | |
| 274 | /* atomic_add_return() is a mb(), put_active() will always see |
| 275 | * the updated sd->s_sibling. |
| 276 | */ |
| 277 | v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active); |
| 278 | |
| 279 | if (v != SD_DEACTIVATED_BIAS) |
| 280 | wait_for_completion(&wait); |
| 281 | |
| 282 | sd->s_sibling = NULL; |
| 283 | } |
| 284 | |
| 285 | static int sysfs_alloc_ino(ino_t *pino) |
| 286 | { |
| 287 | int ino, rc; |
| 288 | |
| 289 | retry: |
| 290 | spin_lock(&sysfs_ino_lock); |
| 291 | rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino); |
| 292 | spin_unlock(&sysfs_ino_lock); |
| 293 | |
| 294 | if (rc == -EAGAIN) { |
| 295 | if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL)) |
| 296 | goto retry; |
| 297 | rc = -ENOMEM; |
| 298 | } |
| 299 | |
| 300 | *pino = ino; |
| 301 | return rc; |
| 302 | } |
| 303 | |
| 304 | static void sysfs_free_ino(ino_t ino) |
| 305 | { |
| 306 | spin_lock(&sysfs_ino_lock); |
| 307 | ida_remove(&sysfs_ino_ida, ino); |
| 308 | spin_unlock(&sysfs_ino_lock); |
| 309 | } |
| 310 | |
| 311 | void release_sysfs_dirent(struct sysfs_dirent * sd) |
| 312 | { |
| 313 | struct sysfs_dirent *parent_sd; |
| 314 | |
| 315 | repeat: |
| 316 | /* Moving/renaming is always done while holding reference. |
| 317 | * sd->s_parent won't change beneath us. |
| 318 | */ |
| 319 | parent_sd = sd->s_parent; |
| 320 | |
| 321 | if (sysfs_type(sd) == SYSFS_KOBJ_LINK) |
| 322 | sysfs_put(sd->s_elem.symlink.target_sd); |
| 323 | if (sysfs_type(sd) & SYSFS_COPY_NAME) |
| 324 | kfree(sd->s_name); |
| 325 | kfree(sd->s_iattr); |
| 326 | sysfs_free_ino(sd->s_ino); |
| 327 | kmem_cache_free(sysfs_dir_cachep, sd); |
| 328 | |
| 329 | sd = parent_sd; |
| 330 | if (sd && atomic_dec_and_test(&sd->s_count)) |
| 331 | goto repeat; |
| 332 | } |
| 333 | |
| 334 | static void sysfs_d_iput(struct dentry * dentry, struct inode * inode) |
| 335 | { |
| 336 | struct sysfs_dirent * sd = dentry->d_fsdata; |
| 337 | |
| 338 | if (sd) { |
| 339 | /* sd->s_dentry is protected with sysfs_assoc_lock. |
| 340 | * This allows sysfs_drop_dentry() to dereference it. |
| 341 | */ |
| 342 | spin_lock(&sysfs_assoc_lock); |
| 343 | |
| 344 | /* The dentry might have been deleted or another |
| 345 | * lookup could have happened updating sd->s_dentry to |
| 346 | * point the new dentry. Ignore if it isn't pointing |
| 347 | * to this dentry. |
| 348 | */ |
| 349 | if (sd->s_dentry == dentry) |
| 350 | sd->s_dentry = NULL; |
| 351 | spin_unlock(&sysfs_assoc_lock); |
| 352 | sysfs_put(sd); |
| 353 | } |
| 354 | iput(inode); |
| 355 | } |
| 356 | |
| 357 | static struct dentry_operations sysfs_dentry_ops = { |
| 358 | .d_iput = sysfs_d_iput, |
| 359 | }; |
| 360 | |
| 361 | struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type) |
| 362 | { |
| 363 | char *dup_name = NULL; |
| 364 | struct sysfs_dirent *sd; |
| 365 | |
| 366 | if (type & SYSFS_COPY_NAME) { |
| 367 | name = dup_name = kstrdup(name, GFP_KERNEL); |
| 368 | if (!name) |
| 369 | return NULL; |
| 370 | } |
| 371 | |
| 372 | sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL); |
| 373 | if (!sd) |
| 374 | goto err_out1; |
| 375 | |
| 376 | if (sysfs_alloc_ino(&sd->s_ino)) |
| 377 | goto err_out2; |
| 378 | |
| 379 | atomic_set(&sd->s_count, 1); |
| 380 | atomic_set(&sd->s_active, 0); |
| 381 | atomic_set(&sd->s_event, 1); |
| 382 | |
| 383 | sd->s_name = name; |
| 384 | sd->s_mode = mode; |
| 385 | sd->s_flags = type; |
| 386 | |
| 387 | return sd; |
| 388 | |
| 389 | err_out2: |
| 390 | kmem_cache_free(sysfs_dir_cachep, sd); |
| 391 | err_out1: |
| 392 | kfree(dup_name); |
| 393 | return NULL; |
| 394 | } |
| 395 | |
| 396 | /** |
| 397 | * sysfs_attach_dentry - associate sysfs_dirent with dentry |
| 398 | * @sd: target sysfs_dirent |
| 399 | * @dentry: dentry to associate |
| 400 | * |
| 401 | * Associate @sd with @dentry. This is protected by |
| 402 | * sysfs_assoc_lock to avoid race with sysfs_d_iput(). |
| 403 | * |
| 404 | * LOCKING: |
| 405 | * mutex_lock(sysfs_mutex) |
| 406 | */ |
| 407 | static void sysfs_attach_dentry(struct sysfs_dirent *sd, struct dentry *dentry) |
| 408 | { |
| 409 | dentry->d_op = &sysfs_dentry_ops; |
| 410 | dentry->d_fsdata = sysfs_get(sd); |
| 411 | |
| 412 | /* protect sd->s_dentry against sysfs_d_iput */ |
| 413 | spin_lock(&sysfs_assoc_lock); |
| 414 | sd->s_dentry = dentry; |
| 415 | spin_unlock(&sysfs_assoc_lock); |
| 416 | |
| 417 | d_rehash(dentry); |
| 418 | } |
| 419 | |
| 420 | static int sysfs_ilookup_test(struct inode *inode, void *arg) |
| 421 | { |
| 422 | struct sysfs_dirent *sd = arg; |
| 423 | return inode->i_ino == sd->s_ino; |
| 424 | } |
| 425 | |
| 426 | /** |
| 427 | * sysfs_addrm_start - prepare for sysfs_dirent add/remove |
| 428 | * @acxt: pointer to sysfs_addrm_cxt to be used |
| 429 | * @parent_sd: parent sysfs_dirent |
| 430 | * |
| 431 | * This function is called when the caller is about to add or |
| 432 | * remove sysfs_dirent under @parent_sd. This function acquires |
| 433 | * sysfs_mutex, grabs inode for @parent_sd if available and lock |
| 434 | * i_mutex of it. @acxt is used to keep and pass context to |
| 435 | * other addrm functions. |
| 436 | * |
| 437 | * LOCKING: |
| 438 | * Kernel thread context (may sleep). sysfs_mutex is locked on |
| 439 | * return. i_mutex of parent inode is locked on return if |
| 440 | * available. |
| 441 | */ |
| 442 | void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt, |
| 443 | struct sysfs_dirent *parent_sd) |
| 444 | { |
| 445 | struct inode *inode; |
| 446 | |
| 447 | memset(acxt, 0, sizeof(*acxt)); |
| 448 | acxt->parent_sd = parent_sd; |
| 449 | |
| 450 | /* Lookup parent inode. inode initialization and I_NEW |
| 451 | * clearing are protected by sysfs_mutex. By grabbing it and |
| 452 | * looking up with _nowait variant, inode state can be |
| 453 | * determined reliably. |
| 454 | */ |
| 455 | mutex_lock(&sysfs_mutex); |
| 456 | |
| 457 | inode = ilookup5_nowait(sysfs_sb, parent_sd->s_ino, sysfs_ilookup_test, |
| 458 | parent_sd); |
| 459 | |
| 460 | if (inode && !(inode->i_state & I_NEW)) { |
| 461 | /* parent inode available */ |
| 462 | acxt->parent_inode = inode; |
| 463 | |
| 464 | /* sysfs_mutex is below i_mutex in lock hierarchy. |
| 465 | * First, trylock i_mutex. If fails, unlock |
| 466 | * sysfs_mutex and lock them in order. |
| 467 | */ |
| 468 | if (!mutex_trylock(&inode->i_mutex)) { |
| 469 | mutex_unlock(&sysfs_mutex); |
| 470 | mutex_lock(&inode->i_mutex); |
| 471 | mutex_lock(&sysfs_mutex); |
| 472 | } |
| 473 | } else |
| 474 | iput(inode); |
| 475 | } |
| 476 | |
| 477 | /** |
| 478 | * sysfs_add_one - add sysfs_dirent to parent |
| 479 | * @acxt: addrm context to use |
| 480 | * @sd: sysfs_dirent to be added |
| 481 | * |
| 482 | * Get @acxt->parent_sd and set sd->s_parent to it and increment |
| 483 | * nlink of parent inode if @sd is a directory. @sd is NOT |
| 484 | * linked into the children list of the parent. The caller |
| 485 | * should invoke sysfs_link_sibling() after this function |
| 486 | * completes if @sd needs to be on the children list. |
| 487 | * |
| 488 | * This function should be called between calls to |
| 489 | * sysfs_addrm_start() and sysfs_addrm_finish() and should be |
| 490 | * passed the same @acxt as passed to sysfs_addrm_start(). |
| 491 | * |
| 492 | * LOCKING: |
| 493 | * Determined by sysfs_addrm_start(). |
| 494 | */ |
| 495 | void sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd) |
| 496 | { |
| 497 | sd->s_parent = sysfs_get(acxt->parent_sd); |
| 498 | |
| 499 | if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode) |
| 500 | inc_nlink(acxt->parent_inode); |
| 501 | |
| 502 | acxt->cnt++; |
| 503 | } |
| 504 | |
| 505 | /** |
| 506 | * sysfs_remove_one - remove sysfs_dirent from parent |
| 507 | * @acxt: addrm context to use |
| 508 | * @sd: sysfs_dirent to be added |
| 509 | * |
| 510 | * Mark @sd removed and drop nlink of parent inode if @sd is a |
| 511 | * directory. @sd is NOT unlinked from the children list of the |
| 512 | * parent. The caller is repsonsible for removing @sd from the |
| 513 | * children list before calling this function. |
| 514 | * |
| 515 | * This function should be called between calls to |
| 516 | * sysfs_addrm_start() and sysfs_addrm_finish() and should be |
| 517 | * passed the same @acxt as passed to sysfs_addrm_start(). |
| 518 | * |
| 519 | * LOCKING: |
| 520 | * Determined by sysfs_addrm_start(). |
| 521 | */ |
| 522 | void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd) |
| 523 | { |
| 524 | BUG_ON(sd->s_sibling || (sd->s_flags & SYSFS_FLAG_REMOVED)); |
| 525 | |
| 526 | sd->s_flags |= SYSFS_FLAG_REMOVED; |
| 527 | sd->s_sibling = acxt->removed; |
| 528 | acxt->removed = sd; |
| 529 | |
| 530 | if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode) |
| 531 | drop_nlink(acxt->parent_inode); |
| 532 | |
| 533 | acxt->cnt++; |
| 534 | } |
| 535 | |
| 536 | /** |
| 537 | * sysfs_drop_dentry - drop dentry for the specified sysfs_dirent |
| 538 | * @sd: target sysfs_dirent |
| 539 | * |
| 540 | * Drop dentry for @sd. @sd must have been unlinked from its |
| 541 | * parent on entry to this function such that it can't be looked |
| 542 | * up anymore. |
| 543 | * |
| 544 | * @sd->s_dentry which is protected with sysfs_assoc_lock points |
| 545 | * to the currently associated dentry but we're not holding a |
| 546 | * reference to it and racing with dput(). Grab dcache_lock and |
| 547 | * verify dentry before dropping it. If @sd->s_dentry is NULL or |
| 548 | * dput() beats us, no need to bother. |
| 549 | */ |
| 550 | static void sysfs_drop_dentry(struct sysfs_dirent *sd) |
| 551 | { |
| 552 | struct dentry *dentry = NULL; |
| 553 | struct inode *inode; |
| 554 | |
| 555 | /* We're not holding a reference to ->s_dentry dentry but the |
| 556 | * field will stay valid as long as sysfs_assoc_lock is held. |
| 557 | */ |
| 558 | spin_lock(&sysfs_assoc_lock); |
| 559 | spin_lock(&dcache_lock); |
| 560 | |
| 561 | /* drop dentry if it's there and dput() didn't kill it yet */ |
| 562 | if (sd->s_dentry && sd->s_dentry->d_inode) { |
| 563 | dentry = dget_locked(sd->s_dentry); |
| 564 | spin_lock(&dentry->d_lock); |
| 565 | __d_drop(dentry); |
| 566 | spin_unlock(&dentry->d_lock); |
| 567 | } |
| 568 | |
| 569 | spin_unlock(&dcache_lock); |
| 570 | spin_unlock(&sysfs_assoc_lock); |
| 571 | |
| 572 | dput(dentry); |
| 573 | |
| 574 | /* adjust nlink and update timestamp */ |
| 575 | inode = ilookup(sysfs_sb, sd->s_ino); |
| 576 | if (inode) { |
| 577 | mutex_lock(&inode->i_mutex); |
| 578 | |
| 579 | inode->i_ctime = CURRENT_TIME; |
| 580 | drop_nlink(inode); |
| 581 | if (sysfs_type(sd) == SYSFS_DIR) |
| 582 | drop_nlink(inode); |
| 583 | |
| 584 | mutex_unlock(&inode->i_mutex); |
| 585 | iput(inode); |
| 586 | } |
| 587 | } |
| 588 | |
| 589 | /** |
| 590 | * sysfs_addrm_finish - finish up sysfs_dirent add/remove |
| 591 | * @acxt: addrm context to finish up |
| 592 | * |
| 593 | * Finish up sysfs_dirent add/remove. Resources acquired by |
| 594 | * sysfs_addrm_start() are released and removed sysfs_dirents are |
| 595 | * cleaned up. Timestamps on the parent inode are updated. |
| 596 | * |
| 597 | * LOCKING: |
| 598 | * All mutexes acquired by sysfs_addrm_start() are released. |
| 599 | * |
| 600 | * RETURNS: |
| 601 | * Number of added/removed sysfs_dirents since sysfs_addrm_start(). |
| 602 | */ |
| 603 | int sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt) |
| 604 | { |
| 605 | /* release resources acquired by sysfs_addrm_start() */ |
| 606 | mutex_unlock(&sysfs_mutex); |
| 607 | if (acxt->parent_inode) { |
| 608 | struct inode *inode = acxt->parent_inode; |
| 609 | |
| 610 | /* if added/removed, update timestamps on the parent */ |
| 611 | if (acxt->cnt) |
| 612 | inode->i_ctime = inode->i_mtime = CURRENT_TIME; |
| 613 | |
| 614 | mutex_unlock(&inode->i_mutex); |
| 615 | iput(inode); |
| 616 | } |
| 617 | |
| 618 | /* kill removed sysfs_dirents */ |
| 619 | while (acxt->removed) { |
| 620 | struct sysfs_dirent *sd = acxt->removed; |
| 621 | |
| 622 | acxt->removed = sd->s_sibling; |
| 623 | sd->s_sibling = NULL; |
| 624 | |
| 625 | sysfs_drop_dentry(sd); |
| 626 | sysfs_deactivate(sd); |
| 627 | sysfs_put(sd); |
| 628 | } |
| 629 | |
| 630 | return acxt->cnt; |
| 631 | } |
| 632 | |
| 633 | /** |
| 634 | * sysfs_find_dirent - find sysfs_dirent with the given name |
| 635 | * @parent_sd: sysfs_dirent to search under |
| 636 | * @name: name to look for |
| 637 | * |
| 638 | * Look for sysfs_dirent with name @name under @parent_sd. |
| 639 | * |
| 640 | * LOCKING: |
| 641 | * mutex_lock(sysfs_mutex) |
| 642 | * |
| 643 | * RETURNS: |
| 644 | * Pointer to sysfs_dirent if found, NULL if not. |
| 645 | */ |
| 646 | struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd, |
| 647 | const unsigned char *name) |
| 648 | { |
| 649 | struct sysfs_dirent *sd; |
| 650 | |
| 651 | for (sd = parent_sd->s_children; sd; sd = sd->s_sibling) |
| 652 | if (sysfs_type(sd) && !strcmp(sd->s_name, name)) |
| 653 | return sd; |
| 654 | return NULL; |
| 655 | } |
| 656 | |
| 657 | /** |
| 658 | * sysfs_get_dirent - find and get sysfs_dirent with the given name |
| 659 | * @parent_sd: sysfs_dirent to search under |
| 660 | * @name: name to look for |
| 661 | * |
| 662 | * Look for sysfs_dirent with name @name under @parent_sd and get |
| 663 | * it if found. |
| 664 | * |
| 665 | * LOCKING: |
| 666 | * Kernel thread context (may sleep). Grabs sysfs_mutex. |
| 667 | * |
| 668 | * RETURNS: |
| 669 | * Pointer to sysfs_dirent if found, NULL if not. |
| 670 | */ |
| 671 | struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd, |
| 672 | const unsigned char *name) |
| 673 | { |
| 674 | struct sysfs_dirent *sd; |
| 675 | |
| 676 | mutex_lock(&sysfs_mutex); |
| 677 | sd = sysfs_find_dirent(parent_sd, name); |
| 678 | sysfs_get(sd); |
| 679 | mutex_unlock(&sysfs_mutex); |
| 680 | |
| 681 | return sd; |
| 682 | } |
| 683 | |
| 684 | static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd, |
| 685 | const char *name, struct sysfs_dirent **p_sd) |
| 686 | { |
| 687 | umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO; |
| 688 | struct sysfs_addrm_cxt acxt; |
| 689 | struct sysfs_dirent *sd; |
| 690 | |
| 691 | /* allocate */ |
| 692 | sd = sysfs_new_dirent(name, mode, SYSFS_DIR); |
| 693 | if (!sd) |
| 694 | return -ENOMEM; |
| 695 | sd->s_elem.dir.kobj = kobj; |
| 696 | |
| 697 | /* link in */ |
| 698 | sysfs_addrm_start(&acxt, parent_sd); |
| 699 | |
| 700 | if (!sysfs_find_dirent(parent_sd, name)) { |
| 701 | sysfs_add_one(&acxt, sd); |
| 702 | sysfs_link_sibling(sd); |
| 703 | } |
| 704 | |
| 705 | if (!sysfs_addrm_finish(&acxt)) { |
| 706 | sysfs_put(sd); |
| 707 | return -EEXIST; |
| 708 | } |
| 709 | |
| 710 | *p_sd = sd; |
| 711 | return 0; |
| 712 | } |
| 713 | |
| 714 | int sysfs_create_subdir(struct kobject *kobj, const char *name, |
| 715 | struct sysfs_dirent **p_sd) |
| 716 | { |
| 717 | return create_dir(kobj, kobj->sd, name, p_sd); |
| 718 | } |
| 719 | |
| 720 | /** |
| 721 | * sysfs_create_dir - create a directory for an object. |
| 722 | * @kobj: object we're creating directory for. |
| 723 | */ |
| 724 | int sysfs_create_dir(struct kobject * kobj) |
| 725 | { |
| 726 | struct sysfs_dirent *parent_sd, *sd; |
| 727 | int error = 0; |
| 728 | |
| 729 | BUG_ON(!kobj); |
| 730 | |
| 731 | if (kobj->parent) |
| 732 | parent_sd = kobj->parent->sd; |
| 733 | else if (sysfs_mount && sysfs_mount->mnt_sb) |
| 734 | parent_sd = sysfs_mount->mnt_sb->s_root->d_fsdata; |
| 735 | else |
| 736 | return -EFAULT; |
| 737 | |
| 738 | error = create_dir(kobj, parent_sd, kobject_name(kobj), &sd); |
| 739 | if (!error) |
| 740 | kobj->sd = sd; |
| 741 | return error; |
| 742 | } |
| 743 | |
| 744 | static int sysfs_count_nlink(struct sysfs_dirent *sd) |
| 745 | { |
| 746 | struct sysfs_dirent *child; |
| 747 | int nr = 0; |
| 748 | |
| 749 | for (child = sd->s_children; child; child = child->s_sibling) |
| 750 | if (sysfs_type(child) == SYSFS_DIR) |
| 751 | nr++; |
| 752 | return nr + 2; |
| 753 | } |
| 754 | |
| 755 | static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry, |
| 756 | struct nameidata *nd) |
| 757 | { |
| 758 | struct dentry *ret = NULL; |
| 759 | struct sysfs_dirent * parent_sd = dentry->d_parent->d_fsdata; |
| 760 | struct sysfs_dirent * sd; |
| 761 | struct bin_attribute *bin_attr; |
| 762 | struct inode *inode; |
| 763 | int found = 0; |
| 764 | |
| 765 | mutex_lock(&sysfs_mutex); |
| 766 | |
| 767 | for (sd = parent_sd->s_children; sd; sd = sd->s_sibling) { |
| 768 | if (sysfs_type(sd) && |
| 769 | !strcmp(sd->s_name, dentry->d_name.name)) { |
| 770 | found = 1; |
| 771 | break; |
| 772 | } |
| 773 | } |
| 774 | |
| 775 | /* no such entry */ |
| 776 | if (!found) |
| 777 | goto out_unlock; |
| 778 | |
| 779 | /* attach dentry and inode */ |
| 780 | inode = sysfs_get_inode(sd); |
| 781 | if (!inode) { |
| 782 | ret = ERR_PTR(-ENOMEM); |
| 783 | goto out_unlock; |
| 784 | } |
| 785 | |
| 786 | if (inode->i_state & I_NEW) { |
| 787 | /* initialize inode according to type */ |
| 788 | switch (sysfs_type(sd)) { |
| 789 | case SYSFS_DIR: |
| 790 | inode->i_op = &sysfs_dir_inode_operations; |
| 791 | inode->i_fop = &sysfs_dir_operations; |
| 792 | inode->i_nlink = sysfs_count_nlink(sd); |
| 793 | break; |
| 794 | case SYSFS_KOBJ_ATTR: |
| 795 | inode->i_size = PAGE_SIZE; |
| 796 | inode->i_fop = &sysfs_file_operations; |
| 797 | break; |
| 798 | case SYSFS_KOBJ_BIN_ATTR: |
| 799 | bin_attr = sd->s_elem.bin_attr.bin_attr; |
| 800 | inode->i_size = bin_attr->size; |
| 801 | inode->i_fop = &bin_fops; |
| 802 | break; |
| 803 | case SYSFS_KOBJ_LINK: |
| 804 | inode->i_op = &sysfs_symlink_inode_operations; |
| 805 | break; |
| 806 | default: |
| 807 | BUG(); |
| 808 | } |
| 809 | } |
| 810 | |
| 811 | sysfs_instantiate(dentry, inode); |
| 812 | sysfs_attach_dentry(sd, dentry); |
| 813 | |
| 814 | out_unlock: |
| 815 | mutex_unlock(&sysfs_mutex); |
| 816 | return ret; |
| 817 | } |
| 818 | |
| 819 | const struct inode_operations sysfs_dir_inode_operations = { |
| 820 | .lookup = sysfs_lookup, |
| 821 | .setattr = sysfs_setattr, |
| 822 | }; |
| 823 | |
| 824 | static void remove_dir(struct sysfs_dirent *sd) |
| 825 | { |
| 826 | struct sysfs_addrm_cxt acxt; |
| 827 | |
| 828 | sysfs_addrm_start(&acxt, sd->s_parent); |
| 829 | sysfs_unlink_sibling(sd); |
| 830 | sysfs_remove_one(&acxt, sd); |
| 831 | sysfs_addrm_finish(&acxt); |
| 832 | } |
| 833 | |
| 834 | void sysfs_remove_subdir(struct sysfs_dirent *sd) |
| 835 | { |
| 836 | remove_dir(sd); |
| 837 | } |
| 838 | |
| 839 | |
| 840 | static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd) |
| 841 | { |
| 842 | struct sysfs_addrm_cxt acxt; |
| 843 | struct sysfs_dirent **pos; |
| 844 | |
| 845 | if (!dir_sd) |
| 846 | return; |
| 847 | |
| 848 | pr_debug("sysfs %s: removing dir\n", dir_sd->s_name); |
| 849 | sysfs_addrm_start(&acxt, dir_sd); |
| 850 | pos = &dir_sd->s_children; |
| 851 | while (*pos) { |
| 852 | struct sysfs_dirent *sd = *pos; |
| 853 | |
| 854 | if (sysfs_type(sd) && sysfs_type(sd) != SYSFS_DIR) { |
| 855 | *pos = sd->s_sibling; |
| 856 | sd->s_sibling = NULL; |
| 857 | sysfs_remove_one(&acxt, sd); |
| 858 | } else |
| 859 | pos = &(*pos)->s_sibling; |
| 860 | } |
| 861 | sysfs_addrm_finish(&acxt); |
| 862 | |
| 863 | remove_dir(dir_sd); |
| 864 | } |
| 865 | |
| 866 | /** |
| 867 | * sysfs_remove_dir - remove an object's directory. |
| 868 | * @kobj: object. |
| 869 | * |
| 870 | * The only thing special about this is that we remove any files in |
| 871 | * the directory before we remove the directory, and we've inlined |
| 872 | * what used to be sysfs_rmdir() below, instead of calling separately. |
| 873 | */ |
| 874 | |
| 875 | void sysfs_remove_dir(struct kobject * kobj) |
| 876 | { |
| 877 | struct sysfs_dirent *sd = kobj->sd; |
| 878 | |
| 879 | spin_lock(&sysfs_assoc_lock); |
| 880 | kobj->sd = NULL; |
| 881 | spin_unlock(&sysfs_assoc_lock); |
| 882 | |
| 883 | __sysfs_remove_dir(sd); |
| 884 | } |
| 885 | |
| 886 | int sysfs_rename_dir(struct kobject * kobj, const char *new_name) |
| 887 | { |
| 888 | struct sysfs_dirent *sd; |
| 889 | struct dentry *parent = NULL; |
| 890 | struct dentry *old_dentry = NULL, *new_dentry = NULL; |
| 891 | struct sysfs_dirent *parent_sd; |
| 892 | const char *dup_name = NULL; |
| 893 | int error; |
| 894 | |
| 895 | if (!kobj->parent) |
| 896 | return -EINVAL; |
| 897 | |
| 898 | /* get dentries */ |
| 899 | sd = kobj->sd; |
| 900 | old_dentry = sysfs_get_dentry(sd); |
| 901 | if (IS_ERR(old_dentry)) { |
| 902 | error = PTR_ERR(old_dentry); |
| 903 | goto out_dput; |
| 904 | } |
| 905 | |
| 906 | parent_sd = kobj->parent->sd; |
| 907 | parent = sysfs_get_dentry(parent_sd); |
| 908 | if (IS_ERR(parent)) { |
| 909 | error = PTR_ERR(parent); |
| 910 | goto out_dput; |
| 911 | } |
| 912 | |
| 913 | /* lock parent and get dentry for new name */ |
| 914 | mutex_lock(&parent->d_inode->i_mutex); |
| 915 | |
| 916 | new_dentry = lookup_one_len(new_name, parent, strlen(new_name)); |
| 917 | if (IS_ERR(new_dentry)) { |
| 918 | error = PTR_ERR(new_dentry); |
| 919 | goto out_unlock; |
| 920 | } |
| 921 | |
| 922 | error = -EINVAL; |
| 923 | if (old_dentry == new_dentry) |
| 924 | goto out_unlock; |
| 925 | |
| 926 | error = -EEXIST; |
| 927 | if (new_dentry->d_inode) |
| 928 | goto out_unlock; |
| 929 | |
| 930 | /* rename kobject and sysfs_dirent */ |
| 931 | error = -ENOMEM; |
| 932 | new_name = dup_name = kstrdup(new_name, GFP_KERNEL); |
| 933 | if (!new_name) |
| 934 | goto out_drop; |
| 935 | |
| 936 | error = kobject_set_name(kobj, "%s", new_name); |
| 937 | if (error) |
| 938 | goto out_drop; |
| 939 | |
| 940 | mutex_lock(&sysfs_mutex); |
| 941 | |
| 942 | dup_name = sd->s_name; |
| 943 | sd->s_name = new_name; |
| 944 | |
| 945 | /* move under the new parent */ |
| 946 | d_add(new_dentry, NULL); |
| 947 | d_move(sd->s_dentry, new_dentry); |
| 948 | |
| 949 | sysfs_unlink_sibling(sd); |
| 950 | sysfs_get(parent_sd); |
| 951 | sysfs_put(sd->s_parent); |
| 952 | sd->s_parent = parent_sd; |
| 953 | sysfs_link_sibling(sd); |
| 954 | |
| 955 | mutex_unlock(&sysfs_mutex); |
| 956 | |
| 957 | error = 0; |
| 958 | goto out_unlock; |
| 959 | |
| 960 | out_drop: |
| 961 | d_drop(new_dentry); |
| 962 | out_unlock: |
| 963 | mutex_unlock(&parent->d_inode->i_mutex); |
| 964 | out_dput: |
| 965 | kfree(dup_name); |
| 966 | dput(parent); |
| 967 | dput(old_dentry); |
| 968 | dput(new_dentry); |
| 969 | return error; |
| 970 | } |
| 971 | |
| 972 | int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj) |
| 973 | { |
| 974 | struct sysfs_dirent *sd = kobj->sd; |
| 975 | struct sysfs_dirent *new_parent_sd; |
| 976 | struct dentry *old_parent, *new_parent = NULL; |
| 977 | struct dentry *old_dentry = NULL, *new_dentry = NULL; |
| 978 | int error; |
| 979 | |
| 980 | BUG_ON(!sd->s_parent); |
| 981 | new_parent_sd = new_parent_kobj->sd ? new_parent_kobj->sd : &sysfs_root; |
| 982 | |
| 983 | /* get dentries */ |
| 984 | old_dentry = sysfs_get_dentry(sd); |
| 985 | if (IS_ERR(old_dentry)) { |
| 986 | error = PTR_ERR(old_dentry); |
| 987 | goto out_dput; |
| 988 | } |
| 989 | old_parent = sd->s_parent->s_dentry; |
| 990 | |
| 991 | new_parent = sysfs_get_dentry(new_parent_sd); |
| 992 | if (IS_ERR(new_parent)) { |
| 993 | error = PTR_ERR(new_parent); |
| 994 | goto out_dput; |
| 995 | } |
| 996 | |
| 997 | if (old_parent->d_inode == new_parent->d_inode) { |
| 998 | error = 0; |
| 999 | goto out_dput; /* nothing to move */ |
| 1000 | } |
| 1001 | again: |
| 1002 | mutex_lock(&old_parent->d_inode->i_mutex); |
| 1003 | if (!mutex_trylock(&new_parent->d_inode->i_mutex)) { |
| 1004 | mutex_unlock(&old_parent->d_inode->i_mutex); |
| 1005 | goto again; |
| 1006 | } |
| 1007 | |
| 1008 | new_dentry = lookup_one_len(kobject_name(kobj), new_parent, strlen(kobject_name(kobj))); |
| 1009 | if (IS_ERR(new_dentry)) { |
| 1010 | error = PTR_ERR(new_dentry); |
| 1011 | goto out_unlock; |
| 1012 | } else |
| 1013 | error = 0; |
| 1014 | d_add(new_dentry, NULL); |
| 1015 | d_move(sd->s_dentry, new_dentry); |
| 1016 | dput(new_dentry); |
| 1017 | |
| 1018 | /* Remove from old parent's list and insert into new parent's list. */ |
| 1019 | mutex_lock(&sysfs_mutex); |
| 1020 | |
| 1021 | sysfs_unlink_sibling(sd); |
| 1022 | sysfs_get(new_parent_sd); |
| 1023 | sysfs_put(sd->s_parent); |
| 1024 | sd->s_parent = new_parent_sd; |
| 1025 | sysfs_link_sibling(sd); |
| 1026 | |
| 1027 | mutex_unlock(&sysfs_mutex); |
| 1028 | |
| 1029 | out_unlock: |
| 1030 | mutex_unlock(&new_parent->d_inode->i_mutex); |
| 1031 | mutex_unlock(&old_parent->d_inode->i_mutex); |
| 1032 | out_dput: |
| 1033 | dput(new_parent); |
| 1034 | dput(old_dentry); |
| 1035 | dput(new_dentry); |
| 1036 | return error; |
| 1037 | } |
| 1038 | |
| 1039 | static int sysfs_dir_open(struct inode *inode, struct file *file) |
| 1040 | { |
| 1041 | struct dentry * dentry = file->f_path.dentry; |
| 1042 | struct sysfs_dirent * parent_sd = dentry->d_fsdata; |
| 1043 | struct sysfs_dirent * sd; |
| 1044 | |
| 1045 | sd = sysfs_new_dirent("_DIR_", 0, 0); |
| 1046 | if (sd) { |
| 1047 | mutex_lock(&sysfs_mutex); |
| 1048 | sd->s_parent = sysfs_get(parent_sd); |
| 1049 | sysfs_link_sibling(sd); |
| 1050 | mutex_unlock(&sysfs_mutex); |
| 1051 | } |
| 1052 | |
| 1053 | file->private_data = sd; |
| 1054 | return sd ? 0 : -ENOMEM; |
| 1055 | } |
| 1056 | |
| 1057 | static int sysfs_dir_close(struct inode *inode, struct file *file) |
| 1058 | { |
| 1059 | struct sysfs_dirent * cursor = file->private_data; |
| 1060 | |
| 1061 | mutex_lock(&sysfs_mutex); |
| 1062 | sysfs_unlink_sibling(cursor); |
| 1063 | mutex_unlock(&sysfs_mutex); |
| 1064 | |
| 1065 | release_sysfs_dirent(cursor); |
| 1066 | |
| 1067 | return 0; |
| 1068 | } |
| 1069 | |
| 1070 | /* Relationship between s_mode and the DT_xxx types */ |
| 1071 | static inline unsigned char dt_type(struct sysfs_dirent *sd) |
| 1072 | { |
| 1073 | return (sd->s_mode >> 12) & 15; |
| 1074 | } |
| 1075 | |
| 1076 | static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir) |
| 1077 | { |
| 1078 | struct dentry *dentry = filp->f_path.dentry; |
| 1079 | struct sysfs_dirent * parent_sd = dentry->d_fsdata; |
| 1080 | struct sysfs_dirent *cursor = filp->private_data; |
| 1081 | struct sysfs_dirent **pos; |
| 1082 | ino_t ino; |
| 1083 | int i = filp->f_pos; |
| 1084 | |
| 1085 | switch (i) { |
| 1086 | case 0: |
| 1087 | ino = parent_sd->s_ino; |
| 1088 | if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0) |
| 1089 | break; |
| 1090 | filp->f_pos++; |
| 1091 | i++; |
| 1092 | /* fallthrough */ |
| 1093 | case 1: |
| 1094 | if (parent_sd->s_parent) |
| 1095 | ino = parent_sd->s_parent->s_ino; |
| 1096 | else |
| 1097 | ino = parent_sd->s_ino; |
| 1098 | if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0) |
| 1099 | break; |
| 1100 | filp->f_pos++; |
| 1101 | i++; |
| 1102 | /* fallthrough */ |
| 1103 | default: |
| 1104 | mutex_lock(&sysfs_mutex); |
| 1105 | |
| 1106 | pos = &parent_sd->s_children; |
| 1107 | while (*pos != cursor) |
| 1108 | pos = &(*pos)->s_sibling; |
| 1109 | |
| 1110 | /* unlink cursor */ |
| 1111 | *pos = cursor->s_sibling; |
| 1112 | |
| 1113 | if (filp->f_pos == 2) |
| 1114 | pos = &parent_sd->s_children; |
| 1115 | |
| 1116 | for ( ; *pos; pos = &(*pos)->s_sibling) { |
| 1117 | struct sysfs_dirent *next = *pos; |
| 1118 | const char * name; |
| 1119 | int len; |
| 1120 | |
| 1121 | if (!sysfs_type(next)) |
| 1122 | continue; |
| 1123 | |
| 1124 | name = next->s_name; |
| 1125 | len = strlen(name); |
| 1126 | ino = next->s_ino; |
| 1127 | |
| 1128 | if (filldir(dirent, name, len, filp->f_pos, ino, |
| 1129 | dt_type(next)) < 0) |
| 1130 | break; |
| 1131 | |
| 1132 | filp->f_pos++; |
| 1133 | } |
| 1134 | |
| 1135 | /* put cursor back in */ |
| 1136 | cursor->s_sibling = *pos; |
| 1137 | *pos = cursor; |
| 1138 | |
| 1139 | mutex_unlock(&sysfs_mutex); |
| 1140 | } |
| 1141 | return 0; |
| 1142 | } |
| 1143 | |
| 1144 | static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin) |
| 1145 | { |
| 1146 | struct dentry * dentry = file->f_path.dentry; |
| 1147 | |
| 1148 | switch (origin) { |
| 1149 | case 1: |
| 1150 | offset += file->f_pos; |
| 1151 | case 0: |
| 1152 | if (offset >= 0) |
| 1153 | break; |
| 1154 | default: |
| 1155 | return -EINVAL; |
| 1156 | } |
| 1157 | if (offset != file->f_pos) { |
| 1158 | mutex_lock(&sysfs_mutex); |
| 1159 | |
| 1160 | file->f_pos = offset; |
| 1161 | if (file->f_pos >= 2) { |
| 1162 | struct sysfs_dirent *sd = dentry->d_fsdata; |
| 1163 | struct sysfs_dirent *cursor = file->private_data; |
| 1164 | struct sysfs_dirent **pos; |
| 1165 | loff_t n = file->f_pos - 2; |
| 1166 | |
| 1167 | sysfs_unlink_sibling(cursor); |
| 1168 | |
| 1169 | pos = &sd->s_children; |
| 1170 | while (n && *pos) { |
| 1171 | struct sysfs_dirent *next = *pos; |
| 1172 | if (sysfs_type(next)) |
| 1173 | n--; |
| 1174 | pos = &(*pos)->s_sibling; |
| 1175 | } |
| 1176 | |
| 1177 | cursor->s_sibling = *pos; |
| 1178 | *pos = cursor; |
| 1179 | } |
| 1180 | |
| 1181 | mutex_unlock(&sysfs_mutex); |
| 1182 | } |
| 1183 | |
| 1184 | return offset; |
| 1185 | } |
| 1186 | |
| 1187 | const struct file_operations sysfs_dir_operations = { |
| 1188 | .open = sysfs_dir_open, |
| 1189 | .release = sysfs_dir_close, |
| 1190 | .llseek = sysfs_dir_lseek, |
| 1191 | .read = generic_read_dir, |
| 1192 | .readdir = sysfs_readdir, |
| 1193 | }; |