| 1 | // SPDX-License-Identifier: GPL-2.0-only |
| 2 | /* |
| 3 | * fs/libfs.c |
| 4 | * Library for filesystems writers. |
| 5 | */ |
| 6 | |
| 7 | #include <linux/blkdev.h> |
| 8 | #include <linux/export.h> |
| 9 | #include <linux/pagemap.h> |
| 10 | #include <linux/slab.h> |
| 11 | #include <linux/cred.h> |
| 12 | #include <linux/mount.h> |
| 13 | #include <linux/vfs.h> |
| 14 | #include <linux/quotaops.h> |
| 15 | #include <linux/mutex.h> |
| 16 | #include <linux/namei.h> |
| 17 | #include <linux/exportfs.h> |
| 18 | #include <linux/iversion.h> |
| 19 | #include <linux/writeback.h> |
| 20 | #include <linux/buffer_head.h> /* sync_mapping_buffers */ |
| 21 | #include <linux/fs_context.h> |
| 22 | #include <linux/pseudo_fs.h> |
| 23 | #include <linux/fsnotify.h> |
| 24 | #include <linux/unicode.h> |
| 25 | #include <linux/fscrypt.h> |
| 26 | |
| 27 | #include <linux/uaccess.h> |
| 28 | |
| 29 | #include "internal.h" |
| 30 | |
| 31 | int simple_getattr(struct mnt_idmap *idmap, const struct path *path, |
| 32 | struct kstat *stat, u32 request_mask, |
| 33 | unsigned int query_flags) |
| 34 | { |
| 35 | struct inode *inode = d_inode(path->dentry); |
| 36 | generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat); |
| 37 | stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9); |
| 38 | return 0; |
| 39 | } |
| 40 | EXPORT_SYMBOL(simple_getattr); |
| 41 | |
| 42 | int simple_statfs(struct dentry *dentry, struct kstatfs *buf) |
| 43 | { |
| 44 | u64 id = huge_encode_dev(dentry->d_sb->s_dev); |
| 45 | |
| 46 | buf->f_fsid = u64_to_fsid(id); |
| 47 | buf->f_type = dentry->d_sb->s_magic; |
| 48 | buf->f_bsize = PAGE_SIZE; |
| 49 | buf->f_namelen = NAME_MAX; |
| 50 | return 0; |
| 51 | } |
| 52 | EXPORT_SYMBOL(simple_statfs); |
| 53 | |
| 54 | /* |
| 55 | * Retaining negative dentries for an in-memory filesystem just wastes |
| 56 | * memory and lookup time: arrange for them to be deleted immediately. |
| 57 | */ |
| 58 | int always_delete_dentry(const struct dentry *dentry) |
| 59 | { |
| 60 | return 1; |
| 61 | } |
| 62 | EXPORT_SYMBOL(always_delete_dentry); |
| 63 | |
| 64 | const struct dentry_operations simple_dentry_operations = { |
| 65 | .d_delete = always_delete_dentry, |
| 66 | }; |
| 67 | EXPORT_SYMBOL(simple_dentry_operations); |
| 68 | |
| 69 | /* |
| 70 | * Lookup the data. This is trivial - if the dentry didn't already |
| 71 | * exist, we know it is negative. Set d_op to delete negative dentries. |
| 72 | */ |
| 73 | struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) |
| 74 | { |
| 75 | if (dentry->d_name.len > NAME_MAX) |
| 76 | return ERR_PTR(-ENAMETOOLONG); |
| 77 | if (!dentry->d_sb->s_d_op) |
| 78 | d_set_d_op(dentry, &simple_dentry_operations); |
| 79 | d_add(dentry, NULL); |
| 80 | return NULL; |
| 81 | } |
| 82 | EXPORT_SYMBOL(simple_lookup); |
| 83 | |
| 84 | int dcache_dir_open(struct inode *inode, struct file *file) |
| 85 | { |
| 86 | file->private_data = d_alloc_cursor(file->f_path.dentry); |
| 87 | |
| 88 | return file->private_data ? 0 : -ENOMEM; |
| 89 | } |
| 90 | EXPORT_SYMBOL(dcache_dir_open); |
| 91 | |
| 92 | int dcache_dir_close(struct inode *inode, struct file *file) |
| 93 | { |
| 94 | dput(file->private_data); |
| 95 | return 0; |
| 96 | } |
| 97 | EXPORT_SYMBOL(dcache_dir_close); |
| 98 | |
| 99 | /* parent is locked at least shared */ |
| 100 | /* |
| 101 | * Returns an element of siblings' list. |
| 102 | * We are looking for <count>th positive after <p>; if |
| 103 | * found, dentry is grabbed and returned to caller. |
| 104 | * If no such element exists, NULL is returned. |
| 105 | */ |
| 106 | static struct dentry *scan_positives(struct dentry *cursor, |
| 107 | struct hlist_node **p, |
| 108 | loff_t count, |
| 109 | struct dentry *last) |
| 110 | { |
| 111 | struct dentry *dentry = cursor->d_parent, *found = NULL; |
| 112 | |
| 113 | spin_lock(&dentry->d_lock); |
| 114 | while (*p) { |
| 115 | struct dentry *d = hlist_entry(*p, struct dentry, d_sib); |
| 116 | p = &d->d_sib.next; |
| 117 | // we must at least skip cursors, to avoid livelocks |
| 118 | if (d->d_flags & DCACHE_DENTRY_CURSOR) |
| 119 | continue; |
| 120 | if (simple_positive(d) && !--count) { |
| 121 | spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED); |
| 122 | if (simple_positive(d)) |
| 123 | found = dget_dlock(d); |
| 124 | spin_unlock(&d->d_lock); |
| 125 | if (likely(found)) |
| 126 | break; |
| 127 | count = 1; |
| 128 | } |
| 129 | if (need_resched()) { |
| 130 | if (!hlist_unhashed(&cursor->d_sib)) |
| 131 | __hlist_del(&cursor->d_sib); |
| 132 | hlist_add_behind(&cursor->d_sib, &d->d_sib); |
| 133 | p = &cursor->d_sib.next; |
| 134 | spin_unlock(&dentry->d_lock); |
| 135 | cond_resched(); |
| 136 | spin_lock(&dentry->d_lock); |
| 137 | } |
| 138 | } |
| 139 | spin_unlock(&dentry->d_lock); |
| 140 | dput(last); |
| 141 | return found; |
| 142 | } |
| 143 | |
| 144 | loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence) |
| 145 | { |
| 146 | struct dentry *dentry = file->f_path.dentry; |
| 147 | switch (whence) { |
| 148 | case 1: |
| 149 | offset += file->f_pos; |
| 150 | fallthrough; |
| 151 | case 0: |
| 152 | if (offset >= 0) |
| 153 | break; |
| 154 | fallthrough; |
| 155 | default: |
| 156 | return -EINVAL; |
| 157 | } |
| 158 | if (offset != file->f_pos) { |
| 159 | struct dentry *cursor = file->private_data; |
| 160 | struct dentry *to = NULL; |
| 161 | |
| 162 | inode_lock_shared(dentry->d_inode); |
| 163 | |
| 164 | if (offset > 2) |
| 165 | to = scan_positives(cursor, &dentry->d_children.first, |
| 166 | offset - 2, NULL); |
| 167 | spin_lock(&dentry->d_lock); |
| 168 | hlist_del_init(&cursor->d_sib); |
| 169 | if (to) |
| 170 | hlist_add_behind(&cursor->d_sib, &to->d_sib); |
| 171 | spin_unlock(&dentry->d_lock); |
| 172 | dput(to); |
| 173 | |
| 174 | file->f_pos = offset; |
| 175 | |
| 176 | inode_unlock_shared(dentry->d_inode); |
| 177 | } |
| 178 | return offset; |
| 179 | } |
| 180 | EXPORT_SYMBOL(dcache_dir_lseek); |
| 181 | |
| 182 | /* |
| 183 | * Directory is locked and all positive dentries in it are safe, since |
| 184 | * for ramfs-type trees they can't go away without unlink() or rmdir(), |
| 185 | * both impossible due to the lock on directory. |
| 186 | */ |
| 187 | |
| 188 | int dcache_readdir(struct file *file, struct dir_context *ctx) |
| 189 | { |
| 190 | struct dentry *dentry = file->f_path.dentry; |
| 191 | struct dentry *cursor = file->private_data; |
| 192 | struct dentry *next = NULL; |
| 193 | struct hlist_node **p; |
| 194 | |
| 195 | if (!dir_emit_dots(file, ctx)) |
| 196 | return 0; |
| 197 | |
| 198 | if (ctx->pos == 2) |
| 199 | p = &dentry->d_children.first; |
| 200 | else |
| 201 | p = &cursor->d_sib.next; |
| 202 | |
| 203 | while ((next = scan_positives(cursor, p, 1, next)) != NULL) { |
| 204 | if (!dir_emit(ctx, next->d_name.name, next->d_name.len, |
| 205 | d_inode(next)->i_ino, |
| 206 | fs_umode_to_dtype(d_inode(next)->i_mode))) |
| 207 | break; |
| 208 | ctx->pos++; |
| 209 | p = &next->d_sib.next; |
| 210 | } |
| 211 | spin_lock(&dentry->d_lock); |
| 212 | hlist_del_init(&cursor->d_sib); |
| 213 | if (next) |
| 214 | hlist_add_before(&cursor->d_sib, &next->d_sib); |
| 215 | spin_unlock(&dentry->d_lock); |
| 216 | dput(next); |
| 217 | |
| 218 | return 0; |
| 219 | } |
| 220 | EXPORT_SYMBOL(dcache_readdir); |
| 221 | |
| 222 | ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos) |
| 223 | { |
| 224 | return -EISDIR; |
| 225 | } |
| 226 | EXPORT_SYMBOL(generic_read_dir); |
| 227 | |
| 228 | const struct file_operations simple_dir_operations = { |
| 229 | .open = dcache_dir_open, |
| 230 | .release = dcache_dir_close, |
| 231 | .llseek = dcache_dir_lseek, |
| 232 | .read = generic_read_dir, |
| 233 | .iterate_shared = dcache_readdir, |
| 234 | .fsync = noop_fsync, |
| 235 | }; |
| 236 | EXPORT_SYMBOL(simple_dir_operations); |
| 237 | |
| 238 | const struct inode_operations simple_dir_inode_operations = { |
| 239 | .lookup = simple_lookup, |
| 240 | }; |
| 241 | EXPORT_SYMBOL(simple_dir_inode_operations); |
| 242 | |
| 243 | static void offset_set(struct dentry *dentry, u32 offset) |
| 244 | { |
| 245 | dentry->d_fsdata = (void *)((uintptr_t)(offset)); |
| 246 | } |
| 247 | |
| 248 | static u32 dentry2offset(struct dentry *dentry) |
| 249 | { |
| 250 | return (u32)((uintptr_t)(dentry->d_fsdata)); |
| 251 | } |
| 252 | |
| 253 | static struct lock_class_key simple_offset_xa_lock; |
| 254 | |
| 255 | /** |
| 256 | * simple_offset_init - initialize an offset_ctx |
| 257 | * @octx: directory offset map to be initialized |
| 258 | * |
| 259 | */ |
| 260 | void simple_offset_init(struct offset_ctx *octx) |
| 261 | { |
| 262 | xa_init_flags(&octx->xa, XA_FLAGS_ALLOC1); |
| 263 | lockdep_set_class(&octx->xa.xa_lock, &simple_offset_xa_lock); |
| 264 | |
| 265 | /* 0 is '.', 1 is '..', so always start with offset 2 */ |
| 266 | octx->next_offset = 2; |
| 267 | } |
| 268 | |
| 269 | /** |
| 270 | * simple_offset_add - Add an entry to a directory's offset map |
| 271 | * @octx: directory offset ctx to be updated |
| 272 | * @dentry: new dentry being added |
| 273 | * |
| 274 | * Returns zero on success. @so_ctx and the dentry offset are updated. |
| 275 | * Otherwise, a negative errno value is returned. |
| 276 | */ |
| 277 | int simple_offset_add(struct offset_ctx *octx, struct dentry *dentry) |
| 278 | { |
| 279 | static const struct xa_limit limit = XA_LIMIT(2, U32_MAX); |
| 280 | u32 offset; |
| 281 | int ret; |
| 282 | |
| 283 | if (dentry2offset(dentry) != 0) |
| 284 | return -EBUSY; |
| 285 | |
| 286 | ret = xa_alloc_cyclic(&octx->xa, &offset, dentry, limit, |
| 287 | &octx->next_offset, GFP_KERNEL); |
| 288 | if (ret < 0) |
| 289 | return ret; |
| 290 | |
| 291 | offset_set(dentry, offset); |
| 292 | return 0; |
| 293 | } |
| 294 | |
| 295 | /** |
| 296 | * simple_offset_remove - Remove an entry to a directory's offset map |
| 297 | * @octx: directory offset ctx to be updated |
| 298 | * @dentry: dentry being removed |
| 299 | * |
| 300 | */ |
| 301 | void simple_offset_remove(struct offset_ctx *octx, struct dentry *dentry) |
| 302 | { |
| 303 | u32 offset; |
| 304 | |
| 305 | offset = dentry2offset(dentry); |
| 306 | if (offset == 0) |
| 307 | return; |
| 308 | |
| 309 | xa_erase(&octx->xa, offset); |
| 310 | offset_set(dentry, 0); |
| 311 | } |
| 312 | |
| 313 | /** |
| 314 | * simple_offset_rename_exchange - exchange rename with directory offsets |
| 315 | * @old_dir: parent of dentry being moved |
| 316 | * @old_dentry: dentry being moved |
| 317 | * @new_dir: destination parent |
| 318 | * @new_dentry: destination dentry |
| 319 | * |
| 320 | * Returns zero on success. Otherwise a negative errno is returned and the |
| 321 | * rename is rolled back. |
| 322 | */ |
| 323 | int simple_offset_rename_exchange(struct inode *old_dir, |
| 324 | struct dentry *old_dentry, |
| 325 | struct inode *new_dir, |
| 326 | struct dentry *new_dentry) |
| 327 | { |
| 328 | struct offset_ctx *old_ctx = old_dir->i_op->get_offset_ctx(old_dir); |
| 329 | struct offset_ctx *new_ctx = new_dir->i_op->get_offset_ctx(new_dir); |
| 330 | u32 old_index = dentry2offset(old_dentry); |
| 331 | u32 new_index = dentry2offset(new_dentry); |
| 332 | int ret; |
| 333 | |
| 334 | simple_offset_remove(old_ctx, old_dentry); |
| 335 | simple_offset_remove(new_ctx, new_dentry); |
| 336 | |
| 337 | ret = simple_offset_add(new_ctx, old_dentry); |
| 338 | if (ret) |
| 339 | goto out_restore; |
| 340 | |
| 341 | ret = simple_offset_add(old_ctx, new_dentry); |
| 342 | if (ret) { |
| 343 | simple_offset_remove(new_ctx, old_dentry); |
| 344 | goto out_restore; |
| 345 | } |
| 346 | |
| 347 | ret = simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry); |
| 348 | if (ret) { |
| 349 | simple_offset_remove(new_ctx, old_dentry); |
| 350 | simple_offset_remove(old_ctx, new_dentry); |
| 351 | goto out_restore; |
| 352 | } |
| 353 | return 0; |
| 354 | |
| 355 | out_restore: |
| 356 | offset_set(old_dentry, old_index); |
| 357 | xa_store(&old_ctx->xa, old_index, old_dentry, GFP_KERNEL); |
| 358 | offset_set(new_dentry, new_index); |
| 359 | xa_store(&new_ctx->xa, new_index, new_dentry, GFP_KERNEL); |
| 360 | return ret; |
| 361 | } |
| 362 | |
| 363 | /** |
| 364 | * simple_offset_destroy - Release offset map |
| 365 | * @octx: directory offset ctx that is about to be destroyed |
| 366 | * |
| 367 | * During fs teardown (eg. umount), a directory's offset map might still |
| 368 | * contain entries. xa_destroy() cleans out anything that remains. |
| 369 | */ |
| 370 | void simple_offset_destroy(struct offset_ctx *octx) |
| 371 | { |
| 372 | xa_destroy(&octx->xa); |
| 373 | } |
| 374 | |
| 375 | /** |
| 376 | * offset_dir_llseek - Advance the read position of a directory descriptor |
| 377 | * @file: an open directory whose position is to be updated |
| 378 | * @offset: a byte offset |
| 379 | * @whence: enumerator describing the starting position for this update |
| 380 | * |
| 381 | * SEEK_END, SEEK_DATA, and SEEK_HOLE are not supported for directories. |
| 382 | * |
| 383 | * Returns the updated read position if successful; otherwise a |
| 384 | * negative errno is returned and the read position remains unchanged. |
| 385 | */ |
| 386 | static loff_t offset_dir_llseek(struct file *file, loff_t offset, int whence) |
| 387 | { |
| 388 | switch (whence) { |
| 389 | case SEEK_CUR: |
| 390 | offset += file->f_pos; |
| 391 | fallthrough; |
| 392 | case SEEK_SET: |
| 393 | if (offset >= 0) |
| 394 | break; |
| 395 | fallthrough; |
| 396 | default: |
| 397 | return -EINVAL; |
| 398 | } |
| 399 | |
| 400 | /* In this case, ->private_data is protected by f_pos_lock */ |
| 401 | file->private_data = NULL; |
| 402 | return vfs_setpos(file, offset, U32_MAX); |
| 403 | } |
| 404 | |
| 405 | static struct dentry *offset_find_next(struct xa_state *xas) |
| 406 | { |
| 407 | struct dentry *child, *found = NULL; |
| 408 | |
| 409 | rcu_read_lock(); |
| 410 | child = xas_next_entry(xas, U32_MAX); |
| 411 | if (!child) |
| 412 | goto out; |
| 413 | spin_lock(&child->d_lock); |
| 414 | if (simple_positive(child)) |
| 415 | found = dget_dlock(child); |
| 416 | spin_unlock(&child->d_lock); |
| 417 | out: |
| 418 | rcu_read_unlock(); |
| 419 | return found; |
| 420 | } |
| 421 | |
| 422 | static bool offset_dir_emit(struct dir_context *ctx, struct dentry *dentry) |
| 423 | { |
| 424 | u32 offset = dentry2offset(dentry); |
| 425 | struct inode *inode = d_inode(dentry); |
| 426 | |
| 427 | return ctx->actor(ctx, dentry->d_name.name, dentry->d_name.len, offset, |
| 428 | inode->i_ino, fs_umode_to_dtype(inode->i_mode)); |
| 429 | } |
| 430 | |
| 431 | static void *offset_iterate_dir(struct inode *inode, struct dir_context *ctx) |
| 432 | { |
| 433 | struct offset_ctx *so_ctx = inode->i_op->get_offset_ctx(inode); |
| 434 | XA_STATE(xas, &so_ctx->xa, ctx->pos); |
| 435 | struct dentry *dentry; |
| 436 | |
| 437 | while (true) { |
| 438 | dentry = offset_find_next(&xas); |
| 439 | if (!dentry) |
| 440 | return ERR_PTR(-ENOENT); |
| 441 | |
| 442 | if (!offset_dir_emit(ctx, dentry)) { |
| 443 | dput(dentry); |
| 444 | break; |
| 445 | } |
| 446 | |
| 447 | dput(dentry); |
| 448 | ctx->pos = xas.xa_index + 1; |
| 449 | } |
| 450 | return NULL; |
| 451 | } |
| 452 | |
| 453 | /** |
| 454 | * offset_readdir - Emit entries starting at offset @ctx->pos |
| 455 | * @file: an open directory to iterate over |
| 456 | * @ctx: directory iteration context |
| 457 | * |
| 458 | * Caller must hold @file's i_rwsem to prevent insertion or removal of |
| 459 | * entries during this call. |
| 460 | * |
| 461 | * On entry, @ctx->pos contains an offset that represents the first entry |
| 462 | * to be read from the directory. |
| 463 | * |
| 464 | * The operation continues until there are no more entries to read, or |
| 465 | * until the ctx->actor indicates there is no more space in the caller's |
| 466 | * output buffer. |
| 467 | * |
| 468 | * On return, @ctx->pos contains an offset that will read the next entry |
| 469 | * in this directory when offset_readdir() is called again with @ctx. |
| 470 | * |
| 471 | * Return values: |
| 472 | * %0 - Complete |
| 473 | */ |
| 474 | static int offset_readdir(struct file *file, struct dir_context *ctx) |
| 475 | { |
| 476 | struct dentry *dir = file->f_path.dentry; |
| 477 | |
| 478 | lockdep_assert_held(&d_inode(dir)->i_rwsem); |
| 479 | |
| 480 | if (!dir_emit_dots(file, ctx)) |
| 481 | return 0; |
| 482 | |
| 483 | /* In this case, ->private_data is protected by f_pos_lock */ |
| 484 | if (ctx->pos == 2) |
| 485 | file->private_data = NULL; |
| 486 | else if (file->private_data == ERR_PTR(-ENOENT)) |
| 487 | return 0; |
| 488 | file->private_data = offset_iterate_dir(d_inode(dir), ctx); |
| 489 | return 0; |
| 490 | } |
| 491 | |
| 492 | const struct file_operations simple_offset_dir_operations = { |
| 493 | .llseek = offset_dir_llseek, |
| 494 | .iterate_shared = offset_readdir, |
| 495 | .read = generic_read_dir, |
| 496 | .fsync = noop_fsync, |
| 497 | }; |
| 498 | |
| 499 | static struct dentry *find_next_child(struct dentry *parent, struct dentry *prev) |
| 500 | { |
| 501 | struct dentry *child = NULL, *d; |
| 502 | |
| 503 | spin_lock(&parent->d_lock); |
| 504 | d = prev ? d_next_sibling(prev) : d_first_child(parent); |
| 505 | hlist_for_each_entry_from(d, d_sib) { |
| 506 | if (simple_positive(d)) { |
| 507 | spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED); |
| 508 | if (simple_positive(d)) |
| 509 | child = dget_dlock(d); |
| 510 | spin_unlock(&d->d_lock); |
| 511 | if (likely(child)) |
| 512 | break; |
| 513 | } |
| 514 | } |
| 515 | spin_unlock(&parent->d_lock); |
| 516 | dput(prev); |
| 517 | return child; |
| 518 | } |
| 519 | |
| 520 | void simple_recursive_removal(struct dentry *dentry, |
| 521 | void (*callback)(struct dentry *)) |
| 522 | { |
| 523 | struct dentry *this = dget(dentry); |
| 524 | while (true) { |
| 525 | struct dentry *victim = NULL, *child; |
| 526 | struct inode *inode = this->d_inode; |
| 527 | |
| 528 | inode_lock(inode); |
| 529 | if (d_is_dir(this)) |
| 530 | inode->i_flags |= S_DEAD; |
| 531 | while ((child = find_next_child(this, victim)) == NULL) { |
| 532 | // kill and ascend |
| 533 | // update metadata while it's still locked |
| 534 | inode_set_ctime_current(inode); |
| 535 | clear_nlink(inode); |
| 536 | inode_unlock(inode); |
| 537 | victim = this; |
| 538 | this = this->d_parent; |
| 539 | inode = this->d_inode; |
| 540 | inode_lock(inode); |
| 541 | if (simple_positive(victim)) { |
| 542 | d_invalidate(victim); // avoid lost mounts |
| 543 | if (d_is_dir(victim)) |
| 544 | fsnotify_rmdir(inode, victim); |
| 545 | else |
| 546 | fsnotify_unlink(inode, victim); |
| 547 | if (callback) |
| 548 | callback(victim); |
| 549 | dput(victim); // unpin it |
| 550 | } |
| 551 | if (victim == dentry) { |
| 552 | inode_set_mtime_to_ts(inode, |
| 553 | inode_set_ctime_current(inode)); |
| 554 | if (d_is_dir(dentry)) |
| 555 | drop_nlink(inode); |
| 556 | inode_unlock(inode); |
| 557 | dput(dentry); |
| 558 | return; |
| 559 | } |
| 560 | } |
| 561 | inode_unlock(inode); |
| 562 | this = child; |
| 563 | } |
| 564 | } |
| 565 | EXPORT_SYMBOL(simple_recursive_removal); |
| 566 | |
| 567 | static const struct super_operations simple_super_operations = { |
| 568 | .statfs = simple_statfs, |
| 569 | }; |
| 570 | |
| 571 | static int pseudo_fs_fill_super(struct super_block *s, struct fs_context *fc) |
| 572 | { |
| 573 | struct pseudo_fs_context *ctx = fc->fs_private; |
| 574 | struct inode *root; |
| 575 | |
| 576 | s->s_maxbytes = MAX_LFS_FILESIZE; |
| 577 | s->s_blocksize = PAGE_SIZE; |
| 578 | s->s_blocksize_bits = PAGE_SHIFT; |
| 579 | s->s_magic = ctx->magic; |
| 580 | s->s_op = ctx->ops ?: &simple_super_operations; |
| 581 | s->s_xattr = ctx->xattr; |
| 582 | s->s_time_gran = 1; |
| 583 | root = new_inode(s); |
| 584 | if (!root) |
| 585 | return -ENOMEM; |
| 586 | |
| 587 | /* |
| 588 | * since this is the first inode, make it number 1. New inodes created |
| 589 | * after this must take care not to collide with it (by passing |
| 590 | * max_reserved of 1 to iunique). |
| 591 | */ |
| 592 | root->i_ino = 1; |
| 593 | root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; |
| 594 | simple_inode_init_ts(root); |
| 595 | s->s_root = d_make_root(root); |
| 596 | if (!s->s_root) |
| 597 | return -ENOMEM; |
| 598 | s->s_d_op = ctx->dops; |
| 599 | return 0; |
| 600 | } |
| 601 | |
| 602 | static int pseudo_fs_get_tree(struct fs_context *fc) |
| 603 | { |
| 604 | return get_tree_nodev(fc, pseudo_fs_fill_super); |
| 605 | } |
| 606 | |
| 607 | static void pseudo_fs_free(struct fs_context *fc) |
| 608 | { |
| 609 | kfree(fc->fs_private); |
| 610 | } |
| 611 | |
| 612 | static const struct fs_context_operations pseudo_fs_context_ops = { |
| 613 | .free = pseudo_fs_free, |
| 614 | .get_tree = pseudo_fs_get_tree, |
| 615 | }; |
| 616 | |
| 617 | /* |
| 618 | * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that |
| 619 | * will never be mountable) |
| 620 | */ |
| 621 | struct pseudo_fs_context *init_pseudo(struct fs_context *fc, |
| 622 | unsigned long magic) |
| 623 | { |
| 624 | struct pseudo_fs_context *ctx; |
| 625 | |
| 626 | ctx = kzalloc(sizeof(struct pseudo_fs_context), GFP_KERNEL); |
| 627 | if (likely(ctx)) { |
| 628 | ctx->magic = magic; |
| 629 | fc->fs_private = ctx; |
| 630 | fc->ops = &pseudo_fs_context_ops; |
| 631 | fc->sb_flags |= SB_NOUSER; |
| 632 | fc->global = true; |
| 633 | } |
| 634 | return ctx; |
| 635 | } |
| 636 | EXPORT_SYMBOL(init_pseudo); |
| 637 | |
| 638 | int simple_open(struct inode *inode, struct file *file) |
| 639 | { |
| 640 | if (inode->i_private) |
| 641 | file->private_data = inode->i_private; |
| 642 | return 0; |
| 643 | } |
| 644 | EXPORT_SYMBOL(simple_open); |
| 645 | |
| 646 | int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) |
| 647 | { |
| 648 | struct inode *inode = d_inode(old_dentry); |
| 649 | |
| 650 | inode_set_mtime_to_ts(dir, |
| 651 | inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode))); |
| 652 | inc_nlink(inode); |
| 653 | ihold(inode); |
| 654 | dget(dentry); |
| 655 | d_instantiate(dentry, inode); |
| 656 | return 0; |
| 657 | } |
| 658 | EXPORT_SYMBOL(simple_link); |
| 659 | |
| 660 | int simple_empty(struct dentry *dentry) |
| 661 | { |
| 662 | struct dentry *child; |
| 663 | int ret = 0; |
| 664 | |
| 665 | spin_lock(&dentry->d_lock); |
| 666 | hlist_for_each_entry(child, &dentry->d_children, d_sib) { |
| 667 | spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); |
| 668 | if (simple_positive(child)) { |
| 669 | spin_unlock(&child->d_lock); |
| 670 | goto out; |
| 671 | } |
| 672 | spin_unlock(&child->d_lock); |
| 673 | } |
| 674 | ret = 1; |
| 675 | out: |
| 676 | spin_unlock(&dentry->d_lock); |
| 677 | return ret; |
| 678 | } |
| 679 | EXPORT_SYMBOL(simple_empty); |
| 680 | |
| 681 | int simple_unlink(struct inode *dir, struct dentry *dentry) |
| 682 | { |
| 683 | struct inode *inode = d_inode(dentry); |
| 684 | |
| 685 | inode_set_mtime_to_ts(dir, |
| 686 | inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode))); |
| 687 | drop_nlink(inode); |
| 688 | dput(dentry); |
| 689 | return 0; |
| 690 | } |
| 691 | EXPORT_SYMBOL(simple_unlink); |
| 692 | |
| 693 | int simple_rmdir(struct inode *dir, struct dentry *dentry) |
| 694 | { |
| 695 | if (!simple_empty(dentry)) |
| 696 | return -ENOTEMPTY; |
| 697 | |
| 698 | drop_nlink(d_inode(dentry)); |
| 699 | simple_unlink(dir, dentry); |
| 700 | drop_nlink(dir); |
| 701 | return 0; |
| 702 | } |
| 703 | EXPORT_SYMBOL(simple_rmdir); |
| 704 | |
| 705 | /** |
| 706 | * simple_rename_timestamp - update the various inode timestamps for rename |
| 707 | * @old_dir: old parent directory |
| 708 | * @old_dentry: dentry that is being renamed |
| 709 | * @new_dir: new parent directory |
| 710 | * @new_dentry: target for rename |
| 711 | * |
| 712 | * POSIX mandates that the old and new parent directories have their ctime and |
| 713 | * mtime updated, and that inodes of @old_dentry and @new_dentry (if any), have |
| 714 | * their ctime updated. |
| 715 | */ |
| 716 | void simple_rename_timestamp(struct inode *old_dir, struct dentry *old_dentry, |
| 717 | struct inode *new_dir, struct dentry *new_dentry) |
| 718 | { |
| 719 | struct inode *newino = d_inode(new_dentry); |
| 720 | |
| 721 | inode_set_mtime_to_ts(old_dir, inode_set_ctime_current(old_dir)); |
| 722 | if (new_dir != old_dir) |
| 723 | inode_set_mtime_to_ts(new_dir, |
| 724 | inode_set_ctime_current(new_dir)); |
| 725 | inode_set_ctime_current(d_inode(old_dentry)); |
| 726 | if (newino) |
| 727 | inode_set_ctime_current(newino); |
| 728 | } |
| 729 | EXPORT_SYMBOL_GPL(simple_rename_timestamp); |
| 730 | |
| 731 | int simple_rename_exchange(struct inode *old_dir, struct dentry *old_dentry, |
| 732 | struct inode *new_dir, struct dentry *new_dentry) |
| 733 | { |
| 734 | bool old_is_dir = d_is_dir(old_dentry); |
| 735 | bool new_is_dir = d_is_dir(new_dentry); |
| 736 | |
| 737 | if (old_dir != new_dir && old_is_dir != new_is_dir) { |
| 738 | if (old_is_dir) { |
| 739 | drop_nlink(old_dir); |
| 740 | inc_nlink(new_dir); |
| 741 | } else { |
| 742 | drop_nlink(new_dir); |
| 743 | inc_nlink(old_dir); |
| 744 | } |
| 745 | } |
| 746 | simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry); |
| 747 | return 0; |
| 748 | } |
| 749 | EXPORT_SYMBOL_GPL(simple_rename_exchange); |
| 750 | |
| 751 | int simple_rename(struct mnt_idmap *idmap, struct inode *old_dir, |
| 752 | struct dentry *old_dentry, struct inode *new_dir, |
| 753 | struct dentry *new_dentry, unsigned int flags) |
| 754 | { |
| 755 | int they_are_dirs = d_is_dir(old_dentry); |
| 756 | |
| 757 | if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) |
| 758 | return -EINVAL; |
| 759 | |
| 760 | if (flags & RENAME_EXCHANGE) |
| 761 | return simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry); |
| 762 | |
| 763 | if (!simple_empty(new_dentry)) |
| 764 | return -ENOTEMPTY; |
| 765 | |
| 766 | if (d_really_is_positive(new_dentry)) { |
| 767 | simple_unlink(new_dir, new_dentry); |
| 768 | if (they_are_dirs) { |
| 769 | drop_nlink(d_inode(new_dentry)); |
| 770 | drop_nlink(old_dir); |
| 771 | } |
| 772 | } else if (they_are_dirs) { |
| 773 | drop_nlink(old_dir); |
| 774 | inc_nlink(new_dir); |
| 775 | } |
| 776 | |
| 777 | simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry); |
| 778 | return 0; |
| 779 | } |
| 780 | EXPORT_SYMBOL(simple_rename); |
| 781 | |
| 782 | /** |
| 783 | * simple_setattr - setattr for simple filesystem |
| 784 | * @idmap: idmap of the target mount |
| 785 | * @dentry: dentry |
| 786 | * @iattr: iattr structure |
| 787 | * |
| 788 | * Returns 0 on success, -error on failure. |
| 789 | * |
| 790 | * simple_setattr is a simple ->setattr implementation without a proper |
| 791 | * implementation of size changes. |
| 792 | * |
| 793 | * It can either be used for in-memory filesystems or special files |
| 794 | * on simple regular filesystems. Anything that needs to change on-disk |
| 795 | * or wire state on size changes needs its own setattr method. |
| 796 | */ |
| 797 | int simple_setattr(struct mnt_idmap *idmap, struct dentry *dentry, |
| 798 | struct iattr *iattr) |
| 799 | { |
| 800 | struct inode *inode = d_inode(dentry); |
| 801 | int error; |
| 802 | |
| 803 | error = setattr_prepare(idmap, dentry, iattr); |
| 804 | if (error) |
| 805 | return error; |
| 806 | |
| 807 | if (iattr->ia_valid & ATTR_SIZE) |
| 808 | truncate_setsize(inode, iattr->ia_size); |
| 809 | setattr_copy(idmap, inode, iattr); |
| 810 | mark_inode_dirty(inode); |
| 811 | return 0; |
| 812 | } |
| 813 | EXPORT_SYMBOL(simple_setattr); |
| 814 | |
| 815 | static int simple_read_folio(struct file *file, struct folio *folio) |
| 816 | { |
| 817 | folio_zero_range(folio, 0, folio_size(folio)); |
| 818 | flush_dcache_folio(folio); |
| 819 | folio_mark_uptodate(folio); |
| 820 | folio_unlock(folio); |
| 821 | return 0; |
| 822 | } |
| 823 | |
| 824 | int simple_write_begin(struct file *file, struct address_space *mapping, |
| 825 | loff_t pos, unsigned len, |
| 826 | struct page **pagep, void **fsdata) |
| 827 | { |
| 828 | struct folio *folio; |
| 829 | |
| 830 | folio = __filemap_get_folio(mapping, pos / PAGE_SIZE, FGP_WRITEBEGIN, |
| 831 | mapping_gfp_mask(mapping)); |
| 832 | if (IS_ERR(folio)) |
| 833 | return PTR_ERR(folio); |
| 834 | |
| 835 | *pagep = &folio->page; |
| 836 | |
| 837 | if (!folio_test_uptodate(folio) && (len != folio_size(folio))) { |
| 838 | size_t from = offset_in_folio(folio, pos); |
| 839 | |
| 840 | folio_zero_segments(folio, 0, from, |
| 841 | from + len, folio_size(folio)); |
| 842 | } |
| 843 | return 0; |
| 844 | } |
| 845 | EXPORT_SYMBOL(simple_write_begin); |
| 846 | |
| 847 | /** |
| 848 | * simple_write_end - .write_end helper for non-block-device FSes |
| 849 | * @file: See .write_end of address_space_operations |
| 850 | * @mapping: " |
| 851 | * @pos: " |
| 852 | * @len: " |
| 853 | * @copied: " |
| 854 | * @page: " |
| 855 | * @fsdata: " |
| 856 | * |
| 857 | * simple_write_end does the minimum needed for updating a page after writing is |
| 858 | * done. It has the same API signature as the .write_end of |
| 859 | * address_space_operations vector. So it can just be set onto .write_end for |
| 860 | * FSes that don't need any other processing. i_mutex is assumed to be held. |
| 861 | * Block based filesystems should use generic_write_end(). |
| 862 | * NOTE: Even though i_size might get updated by this function, mark_inode_dirty |
| 863 | * is not called, so a filesystem that actually does store data in .write_inode |
| 864 | * should extend on what's done here with a call to mark_inode_dirty() in the |
| 865 | * case that i_size has changed. |
| 866 | * |
| 867 | * Use *ONLY* with simple_read_folio() |
| 868 | */ |
| 869 | static int simple_write_end(struct file *file, struct address_space *mapping, |
| 870 | loff_t pos, unsigned len, unsigned copied, |
| 871 | struct page *page, void *fsdata) |
| 872 | { |
| 873 | struct folio *folio = page_folio(page); |
| 874 | struct inode *inode = folio->mapping->host; |
| 875 | loff_t last_pos = pos + copied; |
| 876 | |
| 877 | /* zero the stale part of the folio if we did a short copy */ |
| 878 | if (!folio_test_uptodate(folio)) { |
| 879 | if (copied < len) { |
| 880 | size_t from = offset_in_folio(folio, pos); |
| 881 | |
| 882 | folio_zero_range(folio, from + copied, len - copied); |
| 883 | } |
| 884 | folio_mark_uptodate(folio); |
| 885 | } |
| 886 | /* |
| 887 | * No need to use i_size_read() here, the i_size |
| 888 | * cannot change under us because we hold the i_mutex. |
| 889 | */ |
| 890 | if (last_pos > inode->i_size) |
| 891 | i_size_write(inode, last_pos); |
| 892 | |
| 893 | folio_mark_dirty(folio); |
| 894 | folio_unlock(folio); |
| 895 | folio_put(folio); |
| 896 | |
| 897 | return copied; |
| 898 | } |
| 899 | |
| 900 | /* |
| 901 | * Provides ramfs-style behavior: data in the pagecache, but no writeback. |
| 902 | */ |
| 903 | const struct address_space_operations ram_aops = { |
| 904 | .read_folio = simple_read_folio, |
| 905 | .write_begin = simple_write_begin, |
| 906 | .write_end = simple_write_end, |
| 907 | .dirty_folio = noop_dirty_folio, |
| 908 | }; |
| 909 | EXPORT_SYMBOL(ram_aops); |
| 910 | |
| 911 | /* |
| 912 | * the inodes created here are not hashed. If you use iunique to generate |
| 913 | * unique inode values later for this filesystem, then you must take care |
| 914 | * to pass it an appropriate max_reserved value to avoid collisions. |
| 915 | */ |
| 916 | int simple_fill_super(struct super_block *s, unsigned long magic, |
| 917 | const struct tree_descr *files) |
| 918 | { |
| 919 | struct inode *inode; |
| 920 | struct dentry *dentry; |
| 921 | int i; |
| 922 | |
| 923 | s->s_blocksize = PAGE_SIZE; |
| 924 | s->s_blocksize_bits = PAGE_SHIFT; |
| 925 | s->s_magic = magic; |
| 926 | s->s_op = &simple_super_operations; |
| 927 | s->s_time_gran = 1; |
| 928 | |
| 929 | inode = new_inode(s); |
| 930 | if (!inode) |
| 931 | return -ENOMEM; |
| 932 | /* |
| 933 | * because the root inode is 1, the files array must not contain an |
| 934 | * entry at index 1 |
| 935 | */ |
| 936 | inode->i_ino = 1; |
| 937 | inode->i_mode = S_IFDIR | 0755; |
| 938 | simple_inode_init_ts(inode); |
| 939 | inode->i_op = &simple_dir_inode_operations; |
| 940 | inode->i_fop = &simple_dir_operations; |
| 941 | set_nlink(inode, 2); |
| 942 | s->s_root = d_make_root(inode); |
| 943 | if (!s->s_root) |
| 944 | return -ENOMEM; |
| 945 | for (i = 0; !files->name || files->name[0]; i++, files++) { |
| 946 | if (!files->name) |
| 947 | continue; |
| 948 | |
| 949 | /* warn if it tries to conflict with the root inode */ |
| 950 | if (unlikely(i == 1)) |
| 951 | printk(KERN_WARNING "%s: %s passed in a files array" |
| 952 | "with an index of 1!\n", __func__, |
| 953 | s->s_type->name); |
| 954 | |
| 955 | dentry = d_alloc_name(s->s_root, files->name); |
| 956 | if (!dentry) |
| 957 | return -ENOMEM; |
| 958 | inode = new_inode(s); |
| 959 | if (!inode) { |
| 960 | dput(dentry); |
| 961 | return -ENOMEM; |
| 962 | } |
| 963 | inode->i_mode = S_IFREG | files->mode; |
| 964 | simple_inode_init_ts(inode); |
| 965 | inode->i_fop = files->ops; |
| 966 | inode->i_ino = i; |
| 967 | d_add(dentry, inode); |
| 968 | } |
| 969 | return 0; |
| 970 | } |
| 971 | EXPORT_SYMBOL(simple_fill_super); |
| 972 | |
| 973 | static DEFINE_SPINLOCK(pin_fs_lock); |
| 974 | |
| 975 | int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count) |
| 976 | { |
| 977 | struct vfsmount *mnt = NULL; |
| 978 | spin_lock(&pin_fs_lock); |
| 979 | if (unlikely(!*mount)) { |
| 980 | spin_unlock(&pin_fs_lock); |
| 981 | mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL); |
| 982 | if (IS_ERR(mnt)) |
| 983 | return PTR_ERR(mnt); |
| 984 | spin_lock(&pin_fs_lock); |
| 985 | if (!*mount) |
| 986 | *mount = mnt; |
| 987 | } |
| 988 | mntget(*mount); |
| 989 | ++*count; |
| 990 | spin_unlock(&pin_fs_lock); |
| 991 | mntput(mnt); |
| 992 | return 0; |
| 993 | } |
| 994 | EXPORT_SYMBOL(simple_pin_fs); |
| 995 | |
| 996 | void simple_release_fs(struct vfsmount **mount, int *count) |
| 997 | { |
| 998 | struct vfsmount *mnt; |
| 999 | spin_lock(&pin_fs_lock); |
| 1000 | mnt = *mount; |
| 1001 | if (!--*count) |
| 1002 | *mount = NULL; |
| 1003 | spin_unlock(&pin_fs_lock); |
| 1004 | mntput(mnt); |
| 1005 | } |
| 1006 | EXPORT_SYMBOL(simple_release_fs); |
| 1007 | |
| 1008 | /** |
| 1009 | * simple_read_from_buffer - copy data from the buffer to user space |
| 1010 | * @to: the user space buffer to read to |
| 1011 | * @count: the maximum number of bytes to read |
| 1012 | * @ppos: the current position in the buffer |
| 1013 | * @from: the buffer to read from |
| 1014 | * @available: the size of the buffer |
| 1015 | * |
| 1016 | * The simple_read_from_buffer() function reads up to @count bytes from the |
| 1017 | * buffer @from at offset @ppos into the user space address starting at @to. |
| 1018 | * |
| 1019 | * On success, the number of bytes read is returned and the offset @ppos is |
| 1020 | * advanced by this number, or negative value is returned on error. |
| 1021 | **/ |
| 1022 | ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, |
| 1023 | const void *from, size_t available) |
| 1024 | { |
| 1025 | loff_t pos = *ppos; |
| 1026 | size_t ret; |
| 1027 | |
| 1028 | if (pos < 0) |
| 1029 | return -EINVAL; |
| 1030 | if (pos >= available || !count) |
| 1031 | return 0; |
| 1032 | if (count > available - pos) |
| 1033 | count = available - pos; |
| 1034 | ret = copy_to_user(to, from + pos, count); |
| 1035 | if (ret == count) |
| 1036 | return -EFAULT; |
| 1037 | count -= ret; |
| 1038 | *ppos = pos + count; |
| 1039 | return count; |
| 1040 | } |
| 1041 | EXPORT_SYMBOL(simple_read_from_buffer); |
| 1042 | |
| 1043 | /** |
| 1044 | * simple_write_to_buffer - copy data from user space to the buffer |
| 1045 | * @to: the buffer to write to |
| 1046 | * @available: the size of the buffer |
| 1047 | * @ppos: the current position in the buffer |
| 1048 | * @from: the user space buffer to read from |
| 1049 | * @count: the maximum number of bytes to read |
| 1050 | * |
| 1051 | * The simple_write_to_buffer() function reads up to @count bytes from the user |
| 1052 | * space address starting at @from into the buffer @to at offset @ppos. |
| 1053 | * |
| 1054 | * On success, the number of bytes written is returned and the offset @ppos is |
| 1055 | * advanced by this number, or negative value is returned on error. |
| 1056 | **/ |
| 1057 | ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos, |
| 1058 | const void __user *from, size_t count) |
| 1059 | { |
| 1060 | loff_t pos = *ppos; |
| 1061 | size_t res; |
| 1062 | |
| 1063 | if (pos < 0) |
| 1064 | return -EINVAL; |
| 1065 | if (pos >= available || !count) |
| 1066 | return 0; |
| 1067 | if (count > available - pos) |
| 1068 | count = available - pos; |
| 1069 | res = copy_from_user(to + pos, from, count); |
| 1070 | if (res == count) |
| 1071 | return -EFAULT; |
| 1072 | count -= res; |
| 1073 | *ppos = pos + count; |
| 1074 | return count; |
| 1075 | } |
| 1076 | EXPORT_SYMBOL(simple_write_to_buffer); |
| 1077 | |
| 1078 | /** |
| 1079 | * memory_read_from_buffer - copy data from the buffer |
| 1080 | * @to: the kernel space buffer to read to |
| 1081 | * @count: the maximum number of bytes to read |
| 1082 | * @ppos: the current position in the buffer |
| 1083 | * @from: the buffer to read from |
| 1084 | * @available: the size of the buffer |
| 1085 | * |
| 1086 | * The memory_read_from_buffer() function reads up to @count bytes from the |
| 1087 | * buffer @from at offset @ppos into the kernel space address starting at @to. |
| 1088 | * |
| 1089 | * On success, the number of bytes read is returned and the offset @ppos is |
| 1090 | * advanced by this number, or negative value is returned on error. |
| 1091 | **/ |
| 1092 | ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, |
| 1093 | const void *from, size_t available) |
| 1094 | { |
| 1095 | loff_t pos = *ppos; |
| 1096 | |
| 1097 | if (pos < 0) |
| 1098 | return -EINVAL; |
| 1099 | if (pos >= available) |
| 1100 | return 0; |
| 1101 | if (count > available - pos) |
| 1102 | count = available - pos; |
| 1103 | memcpy(to, from + pos, count); |
| 1104 | *ppos = pos + count; |
| 1105 | |
| 1106 | return count; |
| 1107 | } |
| 1108 | EXPORT_SYMBOL(memory_read_from_buffer); |
| 1109 | |
| 1110 | /* |
| 1111 | * Transaction based IO. |
| 1112 | * The file expects a single write which triggers the transaction, and then |
| 1113 | * possibly a read which collects the result - which is stored in a |
| 1114 | * file-local buffer. |
| 1115 | */ |
| 1116 | |
| 1117 | void simple_transaction_set(struct file *file, size_t n) |
| 1118 | { |
| 1119 | struct simple_transaction_argresp *ar = file->private_data; |
| 1120 | |
| 1121 | BUG_ON(n > SIMPLE_TRANSACTION_LIMIT); |
| 1122 | |
| 1123 | /* |
| 1124 | * The barrier ensures that ar->size will really remain zero until |
| 1125 | * ar->data is ready for reading. |
| 1126 | */ |
| 1127 | smp_mb(); |
| 1128 | ar->size = n; |
| 1129 | } |
| 1130 | EXPORT_SYMBOL(simple_transaction_set); |
| 1131 | |
| 1132 | char *simple_transaction_get(struct file *file, const char __user *buf, size_t size) |
| 1133 | { |
| 1134 | struct simple_transaction_argresp *ar; |
| 1135 | static DEFINE_SPINLOCK(simple_transaction_lock); |
| 1136 | |
| 1137 | if (size > SIMPLE_TRANSACTION_LIMIT - 1) |
| 1138 | return ERR_PTR(-EFBIG); |
| 1139 | |
| 1140 | ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL); |
| 1141 | if (!ar) |
| 1142 | return ERR_PTR(-ENOMEM); |
| 1143 | |
| 1144 | spin_lock(&simple_transaction_lock); |
| 1145 | |
| 1146 | /* only one write allowed per open */ |
| 1147 | if (file->private_data) { |
| 1148 | spin_unlock(&simple_transaction_lock); |
| 1149 | free_page((unsigned long)ar); |
| 1150 | return ERR_PTR(-EBUSY); |
| 1151 | } |
| 1152 | |
| 1153 | file->private_data = ar; |
| 1154 | |
| 1155 | spin_unlock(&simple_transaction_lock); |
| 1156 | |
| 1157 | if (copy_from_user(ar->data, buf, size)) |
| 1158 | return ERR_PTR(-EFAULT); |
| 1159 | |
| 1160 | return ar->data; |
| 1161 | } |
| 1162 | EXPORT_SYMBOL(simple_transaction_get); |
| 1163 | |
| 1164 | ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos) |
| 1165 | { |
| 1166 | struct simple_transaction_argresp *ar = file->private_data; |
| 1167 | |
| 1168 | if (!ar) |
| 1169 | return 0; |
| 1170 | return simple_read_from_buffer(buf, size, pos, ar->data, ar->size); |
| 1171 | } |
| 1172 | EXPORT_SYMBOL(simple_transaction_read); |
| 1173 | |
| 1174 | int simple_transaction_release(struct inode *inode, struct file *file) |
| 1175 | { |
| 1176 | free_page((unsigned long)file->private_data); |
| 1177 | return 0; |
| 1178 | } |
| 1179 | EXPORT_SYMBOL(simple_transaction_release); |
| 1180 | |
| 1181 | /* Simple attribute files */ |
| 1182 | |
| 1183 | struct simple_attr { |
| 1184 | int (*get)(void *, u64 *); |
| 1185 | int (*set)(void *, u64); |
| 1186 | char get_buf[24]; /* enough to store a u64 and "\n\0" */ |
| 1187 | char set_buf[24]; |
| 1188 | void *data; |
| 1189 | const char *fmt; /* format for read operation */ |
| 1190 | struct mutex mutex; /* protects access to these buffers */ |
| 1191 | }; |
| 1192 | |
| 1193 | /* simple_attr_open is called by an actual attribute open file operation |
| 1194 | * to set the attribute specific access operations. */ |
| 1195 | int simple_attr_open(struct inode *inode, struct file *file, |
| 1196 | int (*get)(void *, u64 *), int (*set)(void *, u64), |
| 1197 | const char *fmt) |
| 1198 | { |
| 1199 | struct simple_attr *attr; |
| 1200 | |
| 1201 | attr = kzalloc(sizeof(*attr), GFP_KERNEL); |
| 1202 | if (!attr) |
| 1203 | return -ENOMEM; |
| 1204 | |
| 1205 | attr->get = get; |
| 1206 | attr->set = set; |
| 1207 | attr->data = inode->i_private; |
| 1208 | attr->fmt = fmt; |
| 1209 | mutex_init(&attr->mutex); |
| 1210 | |
| 1211 | file->private_data = attr; |
| 1212 | |
| 1213 | return nonseekable_open(inode, file); |
| 1214 | } |
| 1215 | EXPORT_SYMBOL_GPL(simple_attr_open); |
| 1216 | |
| 1217 | int simple_attr_release(struct inode *inode, struct file *file) |
| 1218 | { |
| 1219 | kfree(file->private_data); |
| 1220 | return 0; |
| 1221 | } |
| 1222 | EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */ |
| 1223 | |
| 1224 | /* read from the buffer that is filled with the get function */ |
| 1225 | ssize_t simple_attr_read(struct file *file, char __user *buf, |
| 1226 | size_t len, loff_t *ppos) |
| 1227 | { |
| 1228 | struct simple_attr *attr; |
| 1229 | size_t size; |
| 1230 | ssize_t ret; |
| 1231 | |
| 1232 | attr = file->private_data; |
| 1233 | |
| 1234 | if (!attr->get) |
| 1235 | return -EACCES; |
| 1236 | |
| 1237 | ret = mutex_lock_interruptible(&attr->mutex); |
| 1238 | if (ret) |
| 1239 | return ret; |
| 1240 | |
| 1241 | if (*ppos && attr->get_buf[0]) { |
| 1242 | /* continued read */ |
| 1243 | size = strlen(attr->get_buf); |
| 1244 | } else { |
| 1245 | /* first read */ |
| 1246 | u64 val; |
| 1247 | ret = attr->get(attr->data, &val); |
| 1248 | if (ret) |
| 1249 | goto out; |
| 1250 | |
| 1251 | size = scnprintf(attr->get_buf, sizeof(attr->get_buf), |
| 1252 | attr->fmt, (unsigned long long)val); |
| 1253 | } |
| 1254 | |
| 1255 | ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size); |
| 1256 | out: |
| 1257 | mutex_unlock(&attr->mutex); |
| 1258 | return ret; |
| 1259 | } |
| 1260 | EXPORT_SYMBOL_GPL(simple_attr_read); |
| 1261 | |
| 1262 | /* interpret the buffer as a number to call the set function with */ |
| 1263 | static ssize_t simple_attr_write_xsigned(struct file *file, const char __user *buf, |
| 1264 | size_t len, loff_t *ppos, bool is_signed) |
| 1265 | { |
| 1266 | struct simple_attr *attr; |
| 1267 | unsigned long long val; |
| 1268 | size_t size; |
| 1269 | ssize_t ret; |
| 1270 | |
| 1271 | attr = file->private_data; |
| 1272 | if (!attr->set) |
| 1273 | return -EACCES; |
| 1274 | |
| 1275 | ret = mutex_lock_interruptible(&attr->mutex); |
| 1276 | if (ret) |
| 1277 | return ret; |
| 1278 | |
| 1279 | ret = -EFAULT; |
| 1280 | size = min(sizeof(attr->set_buf) - 1, len); |
| 1281 | if (copy_from_user(attr->set_buf, buf, size)) |
| 1282 | goto out; |
| 1283 | |
| 1284 | attr->set_buf[size] = '\0'; |
| 1285 | if (is_signed) |
| 1286 | ret = kstrtoll(attr->set_buf, 0, &val); |
| 1287 | else |
| 1288 | ret = kstrtoull(attr->set_buf, 0, &val); |
| 1289 | if (ret) |
| 1290 | goto out; |
| 1291 | ret = attr->set(attr->data, val); |
| 1292 | if (ret == 0) |
| 1293 | ret = len; /* on success, claim we got the whole input */ |
| 1294 | out: |
| 1295 | mutex_unlock(&attr->mutex); |
| 1296 | return ret; |
| 1297 | } |
| 1298 | |
| 1299 | ssize_t simple_attr_write(struct file *file, const char __user *buf, |
| 1300 | size_t len, loff_t *ppos) |
| 1301 | { |
| 1302 | return simple_attr_write_xsigned(file, buf, len, ppos, false); |
| 1303 | } |
| 1304 | EXPORT_SYMBOL_GPL(simple_attr_write); |
| 1305 | |
| 1306 | ssize_t simple_attr_write_signed(struct file *file, const char __user *buf, |
| 1307 | size_t len, loff_t *ppos) |
| 1308 | { |
| 1309 | return simple_attr_write_xsigned(file, buf, len, ppos, true); |
| 1310 | } |
| 1311 | EXPORT_SYMBOL_GPL(simple_attr_write_signed); |
| 1312 | |
| 1313 | /** |
| 1314 | * generic_encode_ino32_fh - generic export_operations->encode_fh function |
| 1315 | * @inode: the object to encode |
| 1316 | * @fh: where to store the file handle fragment |
| 1317 | * @max_len: maximum length to store there (in 4 byte units) |
| 1318 | * @parent: parent directory inode, if wanted |
| 1319 | * |
| 1320 | * This generic encode_fh function assumes that the 32 inode number |
| 1321 | * is suitable for locating an inode, and that the generation number |
| 1322 | * can be used to check that it is still valid. It places them in the |
| 1323 | * filehandle fragment where export_decode_fh expects to find them. |
| 1324 | */ |
| 1325 | int generic_encode_ino32_fh(struct inode *inode, __u32 *fh, int *max_len, |
| 1326 | struct inode *parent) |
| 1327 | { |
| 1328 | struct fid *fid = (void *)fh; |
| 1329 | int len = *max_len; |
| 1330 | int type = FILEID_INO32_GEN; |
| 1331 | |
| 1332 | if (parent && (len < 4)) { |
| 1333 | *max_len = 4; |
| 1334 | return FILEID_INVALID; |
| 1335 | } else if (len < 2) { |
| 1336 | *max_len = 2; |
| 1337 | return FILEID_INVALID; |
| 1338 | } |
| 1339 | |
| 1340 | len = 2; |
| 1341 | fid->i32.ino = inode->i_ino; |
| 1342 | fid->i32.gen = inode->i_generation; |
| 1343 | if (parent) { |
| 1344 | fid->i32.parent_ino = parent->i_ino; |
| 1345 | fid->i32.parent_gen = parent->i_generation; |
| 1346 | len = 4; |
| 1347 | type = FILEID_INO32_GEN_PARENT; |
| 1348 | } |
| 1349 | *max_len = len; |
| 1350 | return type; |
| 1351 | } |
| 1352 | EXPORT_SYMBOL_GPL(generic_encode_ino32_fh); |
| 1353 | |
| 1354 | /** |
| 1355 | * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation |
| 1356 | * @sb: filesystem to do the file handle conversion on |
| 1357 | * @fid: file handle to convert |
| 1358 | * @fh_len: length of the file handle in bytes |
| 1359 | * @fh_type: type of file handle |
| 1360 | * @get_inode: filesystem callback to retrieve inode |
| 1361 | * |
| 1362 | * This function decodes @fid as long as it has one of the well-known |
| 1363 | * Linux filehandle types and calls @get_inode on it to retrieve the |
| 1364 | * inode for the object specified in the file handle. |
| 1365 | */ |
| 1366 | struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid, |
| 1367 | int fh_len, int fh_type, struct inode *(*get_inode) |
| 1368 | (struct super_block *sb, u64 ino, u32 gen)) |
| 1369 | { |
| 1370 | struct inode *inode = NULL; |
| 1371 | |
| 1372 | if (fh_len < 2) |
| 1373 | return NULL; |
| 1374 | |
| 1375 | switch (fh_type) { |
| 1376 | case FILEID_INO32_GEN: |
| 1377 | case FILEID_INO32_GEN_PARENT: |
| 1378 | inode = get_inode(sb, fid->i32.ino, fid->i32.gen); |
| 1379 | break; |
| 1380 | } |
| 1381 | |
| 1382 | return d_obtain_alias(inode); |
| 1383 | } |
| 1384 | EXPORT_SYMBOL_GPL(generic_fh_to_dentry); |
| 1385 | |
| 1386 | /** |
| 1387 | * generic_fh_to_parent - generic helper for the fh_to_parent export operation |
| 1388 | * @sb: filesystem to do the file handle conversion on |
| 1389 | * @fid: file handle to convert |
| 1390 | * @fh_len: length of the file handle in bytes |
| 1391 | * @fh_type: type of file handle |
| 1392 | * @get_inode: filesystem callback to retrieve inode |
| 1393 | * |
| 1394 | * This function decodes @fid as long as it has one of the well-known |
| 1395 | * Linux filehandle types and calls @get_inode on it to retrieve the |
| 1396 | * inode for the _parent_ object specified in the file handle if it |
| 1397 | * is specified in the file handle, or NULL otherwise. |
| 1398 | */ |
| 1399 | struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, |
| 1400 | int fh_len, int fh_type, struct inode *(*get_inode) |
| 1401 | (struct super_block *sb, u64 ino, u32 gen)) |
| 1402 | { |
| 1403 | struct inode *inode = NULL; |
| 1404 | |
| 1405 | if (fh_len <= 2) |
| 1406 | return NULL; |
| 1407 | |
| 1408 | switch (fh_type) { |
| 1409 | case FILEID_INO32_GEN_PARENT: |
| 1410 | inode = get_inode(sb, fid->i32.parent_ino, |
| 1411 | (fh_len > 3 ? fid->i32.parent_gen : 0)); |
| 1412 | break; |
| 1413 | } |
| 1414 | |
| 1415 | return d_obtain_alias(inode); |
| 1416 | } |
| 1417 | EXPORT_SYMBOL_GPL(generic_fh_to_parent); |
| 1418 | |
| 1419 | /** |
| 1420 | * __generic_file_fsync - generic fsync implementation for simple filesystems |
| 1421 | * |
| 1422 | * @file: file to synchronize |
| 1423 | * @start: start offset in bytes |
| 1424 | * @end: end offset in bytes (inclusive) |
| 1425 | * @datasync: only synchronize essential metadata if true |
| 1426 | * |
| 1427 | * This is a generic implementation of the fsync method for simple |
| 1428 | * filesystems which track all non-inode metadata in the buffers list |
| 1429 | * hanging off the address_space structure. |
| 1430 | */ |
| 1431 | int __generic_file_fsync(struct file *file, loff_t start, loff_t end, |
| 1432 | int datasync) |
| 1433 | { |
| 1434 | struct inode *inode = file->f_mapping->host; |
| 1435 | int err; |
| 1436 | int ret; |
| 1437 | |
| 1438 | err = file_write_and_wait_range(file, start, end); |
| 1439 | if (err) |
| 1440 | return err; |
| 1441 | |
| 1442 | inode_lock(inode); |
| 1443 | ret = sync_mapping_buffers(inode->i_mapping); |
| 1444 | if (!(inode->i_state & I_DIRTY_ALL)) |
| 1445 | goto out; |
| 1446 | if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) |
| 1447 | goto out; |
| 1448 | |
| 1449 | err = sync_inode_metadata(inode, 1); |
| 1450 | if (ret == 0) |
| 1451 | ret = err; |
| 1452 | |
| 1453 | out: |
| 1454 | inode_unlock(inode); |
| 1455 | /* check and advance again to catch errors after syncing out buffers */ |
| 1456 | err = file_check_and_advance_wb_err(file); |
| 1457 | if (ret == 0) |
| 1458 | ret = err; |
| 1459 | return ret; |
| 1460 | } |
| 1461 | EXPORT_SYMBOL(__generic_file_fsync); |
| 1462 | |
| 1463 | /** |
| 1464 | * generic_file_fsync - generic fsync implementation for simple filesystems |
| 1465 | * with flush |
| 1466 | * @file: file to synchronize |
| 1467 | * @start: start offset in bytes |
| 1468 | * @end: end offset in bytes (inclusive) |
| 1469 | * @datasync: only synchronize essential metadata if true |
| 1470 | * |
| 1471 | */ |
| 1472 | |
| 1473 | int generic_file_fsync(struct file *file, loff_t start, loff_t end, |
| 1474 | int datasync) |
| 1475 | { |
| 1476 | struct inode *inode = file->f_mapping->host; |
| 1477 | int err; |
| 1478 | |
| 1479 | err = __generic_file_fsync(file, start, end, datasync); |
| 1480 | if (err) |
| 1481 | return err; |
| 1482 | return blkdev_issue_flush(inode->i_sb->s_bdev); |
| 1483 | } |
| 1484 | EXPORT_SYMBOL(generic_file_fsync); |
| 1485 | |
| 1486 | /** |
| 1487 | * generic_check_addressable - Check addressability of file system |
| 1488 | * @blocksize_bits: log of file system block size |
| 1489 | * @num_blocks: number of blocks in file system |
| 1490 | * |
| 1491 | * Determine whether a file system with @num_blocks blocks (and a |
| 1492 | * block size of 2**@blocksize_bits) is addressable by the sector_t |
| 1493 | * and page cache of the system. Return 0 if so and -EFBIG otherwise. |
| 1494 | */ |
| 1495 | int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) |
| 1496 | { |
| 1497 | u64 last_fs_block = num_blocks - 1; |
| 1498 | u64 last_fs_page = |
| 1499 | last_fs_block >> (PAGE_SHIFT - blocksize_bits); |
| 1500 | |
| 1501 | if (unlikely(num_blocks == 0)) |
| 1502 | return 0; |
| 1503 | |
| 1504 | if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT)) |
| 1505 | return -EINVAL; |
| 1506 | |
| 1507 | if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) || |
| 1508 | (last_fs_page > (pgoff_t)(~0ULL))) { |
| 1509 | return -EFBIG; |
| 1510 | } |
| 1511 | return 0; |
| 1512 | } |
| 1513 | EXPORT_SYMBOL(generic_check_addressable); |
| 1514 | |
| 1515 | /* |
| 1516 | * No-op implementation of ->fsync for in-memory filesystems. |
| 1517 | */ |
| 1518 | int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync) |
| 1519 | { |
| 1520 | return 0; |
| 1521 | } |
| 1522 | EXPORT_SYMBOL(noop_fsync); |
| 1523 | |
| 1524 | ssize_t noop_direct_IO(struct kiocb *iocb, struct iov_iter *iter) |
| 1525 | { |
| 1526 | /* |
| 1527 | * iomap based filesystems support direct I/O without need for |
| 1528 | * this callback. However, it still needs to be set in |
| 1529 | * inode->a_ops so that open/fcntl know that direct I/O is |
| 1530 | * generally supported. |
| 1531 | */ |
| 1532 | return -EINVAL; |
| 1533 | } |
| 1534 | EXPORT_SYMBOL_GPL(noop_direct_IO); |
| 1535 | |
| 1536 | /* Because kfree isn't assignment-compatible with void(void*) ;-/ */ |
| 1537 | void kfree_link(void *p) |
| 1538 | { |
| 1539 | kfree(p); |
| 1540 | } |
| 1541 | EXPORT_SYMBOL(kfree_link); |
| 1542 | |
| 1543 | struct inode *alloc_anon_inode(struct super_block *s) |
| 1544 | { |
| 1545 | static const struct address_space_operations anon_aops = { |
| 1546 | .dirty_folio = noop_dirty_folio, |
| 1547 | }; |
| 1548 | struct inode *inode = new_inode_pseudo(s); |
| 1549 | |
| 1550 | if (!inode) |
| 1551 | return ERR_PTR(-ENOMEM); |
| 1552 | |
| 1553 | inode->i_ino = get_next_ino(); |
| 1554 | inode->i_mapping->a_ops = &anon_aops; |
| 1555 | |
| 1556 | /* |
| 1557 | * Mark the inode dirty from the very beginning, |
| 1558 | * that way it will never be moved to the dirty |
| 1559 | * list because mark_inode_dirty() will think |
| 1560 | * that it already _is_ on the dirty list. |
| 1561 | */ |
| 1562 | inode->i_state = I_DIRTY; |
| 1563 | inode->i_mode = S_IRUSR | S_IWUSR; |
| 1564 | inode->i_uid = current_fsuid(); |
| 1565 | inode->i_gid = current_fsgid(); |
| 1566 | inode->i_flags |= S_PRIVATE; |
| 1567 | simple_inode_init_ts(inode); |
| 1568 | return inode; |
| 1569 | } |
| 1570 | EXPORT_SYMBOL(alloc_anon_inode); |
| 1571 | |
| 1572 | /** |
| 1573 | * simple_nosetlease - generic helper for prohibiting leases |
| 1574 | * @filp: file pointer |
| 1575 | * @arg: type of lease to obtain |
| 1576 | * @flp: new lease supplied for insertion |
| 1577 | * @priv: private data for lm_setup operation |
| 1578 | * |
| 1579 | * Generic helper for filesystems that do not wish to allow leases to be set. |
| 1580 | * All arguments are ignored and it just returns -EINVAL. |
| 1581 | */ |
| 1582 | int |
| 1583 | simple_nosetlease(struct file *filp, int arg, struct file_lock **flp, |
| 1584 | void **priv) |
| 1585 | { |
| 1586 | return -EINVAL; |
| 1587 | } |
| 1588 | EXPORT_SYMBOL(simple_nosetlease); |
| 1589 | |
| 1590 | /** |
| 1591 | * simple_get_link - generic helper to get the target of "fast" symlinks |
| 1592 | * @dentry: not used here |
| 1593 | * @inode: the symlink inode |
| 1594 | * @done: not used here |
| 1595 | * |
| 1596 | * Generic helper for filesystems to use for symlink inodes where a pointer to |
| 1597 | * the symlink target is stored in ->i_link. NOTE: this isn't normally called, |
| 1598 | * since as an optimization the path lookup code uses any non-NULL ->i_link |
| 1599 | * directly, without calling ->get_link(). But ->get_link() still must be set, |
| 1600 | * to mark the inode_operations as being for a symlink. |
| 1601 | * |
| 1602 | * Return: the symlink target |
| 1603 | */ |
| 1604 | const char *simple_get_link(struct dentry *dentry, struct inode *inode, |
| 1605 | struct delayed_call *done) |
| 1606 | { |
| 1607 | return inode->i_link; |
| 1608 | } |
| 1609 | EXPORT_SYMBOL(simple_get_link); |
| 1610 | |
| 1611 | const struct inode_operations simple_symlink_inode_operations = { |
| 1612 | .get_link = simple_get_link, |
| 1613 | }; |
| 1614 | EXPORT_SYMBOL(simple_symlink_inode_operations); |
| 1615 | |
| 1616 | /* |
| 1617 | * Operations for a permanently empty directory. |
| 1618 | */ |
| 1619 | static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) |
| 1620 | { |
| 1621 | return ERR_PTR(-ENOENT); |
| 1622 | } |
| 1623 | |
| 1624 | static int empty_dir_getattr(struct mnt_idmap *idmap, |
| 1625 | const struct path *path, struct kstat *stat, |
| 1626 | u32 request_mask, unsigned int query_flags) |
| 1627 | { |
| 1628 | struct inode *inode = d_inode(path->dentry); |
| 1629 | generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat); |
| 1630 | return 0; |
| 1631 | } |
| 1632 | |
| 1633 | static int empty_dir_setattr(struct mnt_idmap *idmap, |
| 1634 | struct dentry *dentry, struct iattr *attr) |
| 1635 | { |
| 1636 | return -EPERM; |
| 1637 | } |
| 1638 | |
| 1639 | static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t size) |
| 1640 | { |
| 1641 | return -EOPNOTSUPP; |
| 1642 | } |
| 1643 | |
| 1644 | static const struct inode_operations empty_dir_inode_operations = { |
| 1645 | .lookup = empty_dir_lookup, |
| 1646 | .permission = generic_permission, |
| 1647 | .setattr = empty_dir_setattr, |
| 1648 | .getattr = empty_dir_getattr, |
| 1649 | .listxattr = empty_dir_listxattr, |
| 1650 | }; |
| 1651 | |
| 1652 | static loff_t empty_dir_llseek(struct file *file, loff_t offset, int whence) |
| 1653 | { |
| 1654 | /* An empty directory has two entries . and .. at offsets 0 and 1 */ |
| 1655 | return generic_file_llseek_size(file, offset, whence, 2, 2); |
| 1656 | } |
| 1657 | |
| 1658 | static int empty_dir_readdir(struct file *file, struct dir_context *ctx) |
| 1659 | { |
| 1660 | dir_emit_dots(file, ctx); |
| 1661 | return 0; |
| 1662 | } |
| 1663 | |
| 1664 | static const struct file_operations empty_dir_operations = { |
| 1665 | .llseek = empty_dir_llseek, |
| 1666 | .read = generic_read_dir, |
| 1667 | .iterate_shared = empty_dir_readdir, |
| 1668 | .fsync = noop_fsync, |
| 1669 | }; |
| 1670 | |
| 1671 | |
| 1672 | void make_empty_dir_inode(struct inode *inode) |
| 1673 | { |
| 1674 | set_nlink(inode, 2); |
| 1675 | inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO; |
| 1676 | inode->i_uid = GLOBAL_ROOT_UID; |
| 1677 | inode->i_gid = GLOBAL_ROOT_GID; |
| 1678 | inode->i_rdev = 0; |
| 1679 | inode->i_size = 0; |
| 1680 | inode->i_blkbits = PAGE_SHIFT; |
| 1681 | inode->i_blocks = 0; |
| 1682 | |
| 1683 | inode->i_op = &empty_dir_inode_operations; |
| 1684 | inode->i_opflags &= ~IOP_XATTR; |
| 1685 | inode->i_fop = &empty_dir_operations; |
| 1686 | } |
| 1687 | |
| 1688 | bool is_empty_dir_inode(struct inode *inode) |
| 1689 | { |
| 1690 | return (inode->i_fop == &empty_dir_operations) && |
| 1691 | (inode->i_op == &empty_dir_inode_operations); |
| 1692 | } |
| 1693 | |
| 1694 | #if IS_ENABLED(CONFIG_UNICODE) |
| 1695 | /** |
| 1696 | * generic_ci_d_compare - generic d_compare implementation for casefolding filesystems |
| 1697 | * @dentry: dentry whose name we are checking against |
| 1698 | * @len: len of name of dentry |
| 1699 | * @str: str pointer to name of dentry |
| 1700 | * @name: Name to compare against |
| 1701 | * |
| 1702 | * Return: 0 if names match, 1 if mismatch, or -ERRNO |
| 1703 | */ |
| 1704 | static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len, |
| 1705 | const char *str, const struct qstr *name) |
| 1706 | { |
| 1707 | const struct dentry *parent = READ_ONCE(dentry->d_parent); |
| 1708 | const struct inode *dir = READ_ONCE(parent->d_inode); |
| 1709 | const struct super_block *sb = dentry->d_sb; |
| 1710 | const struct unicode_map *um = sb->s_encoding; |
| 1711 | struct qstr qstr = QSTR_INIT(str, len); |
| 1712 | char strbuf[DNAME_INLINE_LEN]; |
| 1713 | int ret; |
| 1714 | |
| 1715 | if (!dir || !IS_CASEFOLDED(dir)) |
| 1716 | goto fallback; |
| 1717 | /* |
| 1718 | * If the dentry name is stored in-line, then it may be concurrently |
| 1719 | * modified by a rename. If this happens, the VFS will eventually retry |
| 1720 | * the lookup, so it doesn't matter what ->d_compare() returns. |
| 1721 | * However, it's unsafe to call utf8_strncasecmp() with an unstable |
| 1722 | * string. Therefore, we have to copy the name into a temporary buffer. |
| 1723 | */ |
| 1724 | if (len <= DNAME_INLINE_LEN - 1) { |
| 1725 | memcpy(strbuf, str, len); |
| 1726 | strbuf[len] = 0; |
| 1727 | qstr.name = strbuf; |
| 1728 | /* prevent compiler from optimizing out the temporary buffer */ |
| 1729 | barrier(); |
| 1730 | } |
| 1731 | ret = utf8_strncasecmp(um, name, &qstr); |
| 1732 | if (ret >= 0) |
| 1733 | return ret; |
| 1734 | |
| 1735 | if (sb_has_strict_encoding(sb)) |
| 1736 | return -EINVAL; |
| 1737 | fallback: |
| 1738 | if (len != name->len) |
| 1739 | return 1; |
| 1740 | return !!memcmp(str, name->name, len); |
| 1741 | } |
| 1742 | |
| 1743 | /** |
| 1744 | * generic_ci_d_hash - generic d_hash implementation for casefolding filesystems |
| 1745 | * @dentry: dentry of the parent directory |
| 1746 | * @str: qstr of name whose hash we should fill in |
| 1747 | * |
| 1748 | * Return: 0 if hash was successful or unchanged, and -EINVAL on error |
| 1749 | */ |
| 1750 | static int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str) |
| 1751 | { |
| 1752 | const struct inode *dir = READ_ONCE(dentry->d_inode); |
| 1753 | struct super_block *sb = dentry->d_sb; |
| 1754 | const struct unicode_map *um = sb->s_encoding; |
| 1755 | int ret = 0; |
| 1756 | |
| 1757 | if (!dir || !IS_CASEFOLDED(dir)) |
| 1758 | return 0; |
| 1759 | |
| 1760 | ret = utf8_casefold_hash(um, dentry, str); |
| 1761 | if (ret < 0 && sb_has_strict_encoding(sb)) |
| 1762 | return -EINVAL; |
| 1763 | return 0; |
| 1764 | } |
| 1765 | |
| 1766 | static const struct dentry_operations generic_ci_dentry_ops = { |
| 1767 | .d_hash = generic_ci_d_hash, |
| 1768 | .d_compare = generic_ci_d_compare, |
| 1769 | }; |
| 1770 | #endif |
| 1771 | |
| 1772 | #ifdef CONFIG_FS_ENCRYPTION |
| 1773 | static const struct dentry_operations generic_encrypted_dentry_ops = { |
| 1774 | .d_revalidate = fscrypt_d_revalidate, |
| 1775 | }; |
| 1776 | #endif |
| 1777 | |
| 1778 | #if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE) |
| 1779 | static const struct dentry_operations generic_encrypted_ci_dentry_ops = { |
| 1780 | .d_hash = generic_ci_d_hash, |
| 1781 | .d_compare = generic_ci_d_compare, |
| 1782 | .d_revalidate = fscrypt_d_revalidate, |
| 1783 | }; |
| 1784 | #endif |
| 1785 | |
| 1786 | /** |
| 1787 | * generic_set_encrypted_ci_d_ops - helper for setting d_ops for given dentry |
| 1788 | * @dentry: dentry to set ops on |
| 1789 | * |
| 1790 | * Casefolded directories need d_hash and d_compare set, so that the dentries |
| 1791 | * contained in them are handled case-insensitively. Note that these operations |
| 1792 | * are needed on the parent directory rather than on the dentries in it, and |
| 1793 | * while the casefolding flag can be toggled on and off on an empty directory, |
| 1794 | * dentry_operations can't be changed later. As a result, if the filesystem has |
| 1795 | * casefolding support enabled at all, we have to give all dentries the |
| 1796 | * casefolding operations even if their inode doesn't have the casefolding flag |
| 1797 | * currently (and thus the casefolding ops would be no-ops for now). |
| 1798 | * |
| 1799 | * Encryption works differently in that the only dentry operation it needs is |
| 1800 | * d_revalidate, which it only needs on dentries that have the no-key name flag. |
| 1801 | * The no-key flag can't be set "later", so we don't have to worry about that. |
| 1802 | * |
| 1803 | * Finally, to maximize compatibility with overlayfs (which isn't compatible |
| 1804 | * with certain dentry operations) and to avoid taking an unnecessary |
| 1805 | * performance hit, we use custom dentry_operations for each possible |
| 1806 | * combination rather than always installing all operations. |
| 1807 | */ |
| 1808 | void generic_set_encrypted_ci_d_ops(struct dentry *dentry) |
| 1809 | { |
| 1810 | #ifdef CONFIG_FS_ENCRYPTION |
| 1811 | bool needs_encrypt_ops = dentry->d_flags & DCACHE_NOKEY_NAME; |
| 1812 | #endif |
| 1813 | #if IS_ENABLED(CONFIG_UNICODE) |
| 1814 | bool needs_ci_ops = dentry->d_sb->s_encoding; |
| 1815 | #endif |
| 1816 | #if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE) |
| 1817 | if (needs_encrypt_ops && needs_ci_ops) { |
| 1818 | d_set_d_op(dentry, &generic_encrypted_ci_dentry_ops); |
| 1819 | return; |
| 1820 | } |
| 1821 | #endif |
| 1822 | #ifdef CONFIG_FS_ENCRYPTION |
| 1823 | if (needs_encrypt_ops) { |
| 1824 | d_set_d_op(dentry, &generic_encrypted_dentry_ops); |
| 1825 | return; |
| 1826 | } |
| 1827 | #endif |
| 1828 | #if IS_ENABLED(CONFIG_UNICODE) |
| 1829 | if (needs_ci_ops) { |
| 1830 | d_set_d_op(dentry, &generic_ci_dentry_ops); |
| 1831 | return; |
| 1832 | } |
| 1833 | #endif |
| 1834 | } |
| 1835 | EXPORT_SYMBOL(generic_set_encrypted_ci_d_ops); |
| 1836 | |
| 1837 | /** |
| 1838 | * inode_maybe_inc_iversion - increments i_version |
| 1839 | * @inode: inode with the i_version that should be updated |
| 1840 | * @force: increment the counter even if it's not necessary? |
| 1841 | * |
| 1842 | * Every time the inode is modified, the i_version field must be seen to have |
| 1843 | * changed by any observer. |
| 1844 | * |
| 1845 | * If "force" is set or the QUERIED flag is set, then ensure that we increment |
| 1846 | * the value, and clear the queried flag. |
| 1847 | * |
| 1848 | * In the common case where neither is set, then we can return "false" without |
| 1849 | * updating i_version. |
| 1850 | * |
| 1851 | * If this function returns false, and no other metadata has changed, then we |
| 1852 | * can avoid logging the metadata. |
| 1853 | */ |
| 1854 | bool inode_maybe_inc_iversion(struct inode *inode, bool force) |
| 1855 | { |
| 1856 | u64 cur, new; |
| 1857 | |
| 1858 | /* |
| 1859 | * The i_version field is not strictly ordered with any other inode |
| 1860 | * information, but the legacy inode_inc_iversion code used a spinlock |
| 1861 | * to serialize increments. |
| 1862 | * |
| 1863 | * Here, we add full memory barriers to ensure that any de-facto |
| 1864 | * ordering with other info is preserved. |
| 1865 | * |
| 1866 | * This barrier pairs with the barrier in inode_query_iversion() |
| 1867 | */ |
| 1868 | smp_mb(); |
| 1869 | cur = inode_peek_iversion_raw(inode); |
| 1870 | do { |
| 1871 | /* If flag is clear then we needn't do anything */ |
| 1872 | if (!force && !(cur & I_VERSION_QUERIED)) |
| 1873 | return false; |
| 1874 | |
| 1875 | /* Since lowest bit is flag, add 2 to avoid it */ |
| 1876 | new = (cur & ~I_VERSION_QUERIED) + I_VERSION_INCREMENT; |
| 1877 | } while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new)); |
| 1878 | return true; |
| 1879 | } |
| 1880 | EXPORT_SYMBOL(inode_maybe_inc_iversion); |
| 1881 | |
| 1882 | /** |
| 1883 | * inode_query_iversion - read i_version for later use |
| 1884 | * @inode: inode from which i_version should be read |
| 1885 | * |
| 1886 | * Read the inode i_version counter. This should be used by callers that wish |
| 1887 | * to store the returned i_version for later comparison. This will guarantee |
| 1888 | * that a later query of the i_version will result in a different value if |
| 1889 | * anything has changed. |
| 1890 | * |
| 1891 | * In this implementation, we fetch the current value, set the QUERIED flag and |
| 1892 | * then try to swap it into place with a cmpxchg, if it wasn't already set. If |
| 1893 | * that fails, we try again with the newly fetched value from the cmpxchg. |
| 1894 | */ |
| 1895 | u64 inode_query_iversion(struct inode *inode) |
| 1896 | { |
| 1897 | u64 cur, new; |
| 1898 | |
| 1899 | cur = inode_peek_iversion_raw(inode); |
| 1900 | do { |
| 1901 | /* If flag is already set, then no need to swap */ |
| 1902 | if (cur & I_VERSION_QUERIED) { |
| 1903 | /* |
| 1904 | * This barrier (and the implicit barrier in the |
| 1905 | * cmpxchg below) pairs with the barrier in |
| 1906 | * inode_maybe_inc_iversion(). |
| 1907 | */ |
| 1908 | smp_mb(); |
| 1909 | break; |
| 1910 | } |
| 1911 | |
| 1912 | new = cur | I_VERSION_QUERIED; |
| 1913 | } while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new)); |
| 1914 | return cur >> I_VERSION_QUERIED_SHIFT; |
| 1915 | } |
| 1916 | EXPORT_SYMBOL(inode_query_iversion); |
| 1917 | |
| 1918 | ssize_t direct_write_fallback(struct kiocb *iocb, struct iov_iter *iter, |
| 1919 | ssize_t direct_written, ssize_t buffered_written) |
| 1920 | { |
| 1921 | struct address_space *mapping = iocb->ki_filp->f_mapping; |
| 1922 | loff_t pos = iocb->ki_pos - buffered_written; |
| 1923 | loff_t end = iocb->ki_pos - 1; |
| 1924 | int err; |
| 1925 | |
| 1926 | /* |
| 1927 | * If the buffered write fallback returned an error, we want to return |
| 1928 | * the number of bytes which were written by direct I/O, or the error |
| 1929 | * code if that was zero. |
| 1930 | * |
| 1931 | * Note that this differs from normal direct-io semantics, which will |
| 1932 | * return -EFOO even if some bytes were written. |
| 1933 | */ |
| 1934 | if (unlikely(buffered_written < 0)) { |
| 1935 | if (direct_written) |
| 1936 | return direct_written; |
| 1937 | return buffered_written; |
| 1938 | } |
| 1939 | |
| 1940 | /* |
| 1941 | * We need to ensure that the page cache pages are written to disk and |
| 1942 | * invalidated to preserve the expected O_DIRECT semantics. |
| 1943 | */ |
| 1944 | err = filemap_write_and_wait_range(mapping, pos, end); |
| 1945 | if (err < 0) { |
| 1946 | /* |
| 1947 | * We don't know how much we wrote, so just return the number of |
| 1948 | * bytes which were direct-written |
| 1949 | */ |
| 1950 | iocb->ki_pos -= buffered_written; |
| 1951 | if (direct_written) |
| 1952 | return direct_written; |
| 1953 | return err; |
| 1954 | } |
| 1955 | invalidate_mapping_pages(mapping, pos >> PAGE_SHIFT, end >> PAGE_SHIFT); |
| 1956 | return direct_written + buffered_written; |
| 1957 | } |
| 1958 | EXPORT_SYMBOL_GPL(direct_write_fallback); |
| 1959 | |
| 1960 | /** |
| 1961 | * simple_inode_init_ts - initialize the timestamps for a new inode |
| 1962 | * @inode: inode to be initialized |
| 1963 | * |
| 1964 | * When a new inode is created, most filesystems set the timestamps to the |
| 1965 | * current time. Add a helper to do this. |
| 1966 | */ |
| 1967 | struct timespec64 simple_inode_init_ts(struct inode *inode) |
| 1968 | { |
| 1969 | struct timespec64 ts = inode_set_ctime_current(inode); |
| 1970 | |
| 1971 | inode_set_atime_to_ts(inode, ts); |
| 1972 | inode_set_mtime_to_ts(inode, ts); |
| 1973 | return ts; |
| 1974 | } |
| 1975 | EXPORT_SYMBOL(simple_inode_init_ts); |