659 lines · c
1// SPDX-License-Identifier: GPL-2.0+2/*3 * NILFS directory entry operations4 *5 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.6 *7 * Modified for NILFS by Amagai Yoshiji.8 */9/*10 * linux/fs/ext2/dir.c11 *12 * Copyright (C) 1992, 1993, 1994, 199513 * Remy Card (card@masi.ibp.fr)14 * Laboratoire MASI - Institut Blaise Pascal15 * Universite Pierre et Marie Curie (Paris VI)16 *17 * from18 *19 * linux/fs/minix/dir.c20 *21 * Copyright (C) 1991, 1992 Linus Torvalds22 *23 * ext2 directory handling functions24 *25 * Big-endian to little-endian byte-swapping/bitmaps by26 * David S. Miller (davem@caip.rutgers.edu), 199527 *28 * All code that works with directory layout had been switched to pagecache29 * and moved here. AV30 */31 32#include <linux/pagemap.h>33#include "nilfs.h"34#include "page.h"35 36static inline unsigned int nilfs_rec_len_from_disk(__le16 dlen)37{38 unsigned int len = le16_to_cpu(dlen);39 40#if (PAGE_SIZE >= 65536)41 if (len == NILFS_MAX_REC_LEN)42 return 1 << 16;43#endif44 return len;45}46 47static inline __le16 nilfs_rec_len_to_disk(unsigned int len)48{49#if (PAGE_SIZE >= 65536)50 if (len == (1 << 16))51 return cpu_to_le16(NILFS_MAX_REC_LEN);52 53 BUG_ON(len > (1 << 16));54#endif55 return cpu_to_le16(len);56}57 58/*59 * nilfs uses block-sized chunks. Arguably, sector-sized ones would be60 * more robust, but we have what we have61 */62static inline unsigned int nilfs_chunk_size(struct inode *inode)63{64 return inode->i_sb->s_blocksize;65}66 67/*68 * Return the offset into page `page_nr' of the last valid69 * byte in that page, plus one.70 */71static unsigned int nilfs_last_byte(struct inode *inode, unsigned long page_nr)72{73 unsigned int last_byte = inode->i_size;74 75 last_byte -= page_nr << PAGE_SHIFT;76 if (last_byte > PAGE_SIZE)77 last_byte = PAGE_SIZE;78 return last_byte;79}80 81static int nilfs_prepare_chunk(struct folio *folio, unsigned int from,82 unsigned int to)83{84 loff_t pos = folio_pos(folio) + from;85 86 return __block_write_begin(folio, pos, to - from, nilfs_get_block);87}88 89static void nilfs_commit_chunk(struct folio *folio,90 struct address_space *mapping, size_t from, size_t to)91{92 struct inode *dir = mapping->host;93 loff_t pos = folio_pos(folio) + from;94 size_t copied, len = to - from;95 unsigned int nr_dirty;96 int err;97 98 nr_dirty = nilfs_page_count_clean_buffers(&folio->page, from, to);99 copied = block_write_end(NULL, mapping, pos, len, len, folio, NULL);100 if (pos + copied > dir->i_size)101 i_size_write(dir, pos + copied);102 if (IS_DIRSYNC(dir))103 nilfs_set_transaction_flag(NILFS_TI_SYNC);104 err = nilfs_set_file_dirty(dir, nr_dirty);105 WARN_ON(err); /* do not happen */106 folio_unlock(folio);107}108 109static bool nilfs_check_folio(struct folio *folio, char *kaddr)110{111 struct inode *dir = folio->mapping->host;112 struct super_block *sb = dir->i_sb;113 unsigned int chunk_size = nilfs_chunk_size(dir);114 size_t offs, rec_len;115 size_t limit = folio_size(folio);116 struct nilfs_dir_entry *p;117 char *error;118 119 if (dir->i_size < folio_pos(folio) + limit) {120 limit = dir->i_size - folio_pos(folio);121 if (limit & (chunk_size - 1))122 goto Ebadsize;123 if (!limit)124 goto out;125 }126 for (offs = 0; offs <= limit - NILFS_DIR_REC_LEN(1); offs += rec_len) {127 p = (struct nilfs_dir_entry *)(kaddr + offs);128 rec_len = nilfs_rec_len_from_disk(p->rec_len);129 130 if (rec_len < NILFS_DIR_REC_LEN(1))131 goto Eshort;132 if (rec_len & 3)133 goto Ealign;134 if (rec_len < NILFS_DIR_REC_LEN(p->name_len))135 goto Enamelen;136 if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))137 goto Espan;138 if (unlikely(p->inode &&139 NILFS_PRIVATE_INODE(le64_to_cpu(p->inode))))140 goto Einumber;141 }142 if (offs != limit)143 goto Eend;144out:145 folio_set_checked(folio);146 return true;147 148 /* Too bad, we had an error */149 150Ebadsize:151 nilfs_error(sb,152 "size of directory #%lu is not a multiple of chunk size",153 dir->i_ino);154 goto fail;155Eshort:156 error = "rec_len is smaller than minimal";157 goto bad_entry;158Ealign:159 error = "unaligned directory entry";160 goto bad_entry;161Enamelen:162 error = "rec_len is too small for name_len";163 goto bad_entry;164Espan:165 error = "directory entry across blocks";166 goto bad_entry;167Einumber:168 error = "disallowed inode number";169bad_entry:170 nilfs_error(sb,171 "bad entry in directory #%lu: %s - offset=%lu, inode=%lu, rec_len=%zd, name_len=%d",172 dir->i_ino, error, (folio->index << PAGE_SHIFT) + offs,173 (unsigned long)le64_to_cpu(p->inode),174 rec_len, p->name_len);175 goto fail;176Eend:177 p = (struct nilfs_dir_entry *)(kaddr + offs);178 nilfs_error(sb,179 "entry in directory #%lu spans the page boundary offset=%lu, inode=%lu",180 dir->i_ino, (folio->index << PAGE_SHIFT) + offs,181 (unsigned long)le64_to_cpu(p->inode));182fail:183 return false;184}185 186static void *nilfs_get_folio(struct inode *dir, unsigned long n,187 struct folio **foliop)188{189 struct address_space *mapping = dir->i_mapping;190 struct folio *folio = read_mapping_folio(mapping, n, NULL);191 void *kaddr;192 193 if (IS_ERR(folio))194 return folio;195 196 kaddr = kmap_local_folio(folio, 0);197 if (unlikely(!folio_test_checked(folio))) {198 if (!nilfs_check_folio(folio, kaddr))199 goto fail;200 }201 202 *foliop = folio;203 return kaddr;204 205fail:206 folio_release_kmap(folio, kaddr);207 return ERR_PTR(-EIO);208}209 210/*211 * NOTE! unlike strncmp, nilfs_match returns 1 for success, 0 for failure.212 *213 * len <= NILFS_NAME_LEN and de != NULL are guaranteed by caller.214 */215static int216nilfs_match(int len, const unsigned char *name, struct nilfs_dir_entry *de)217{218 if (len != de->name_len)219 return 0;220 if (!de->inode)221 return 0;222 return !memcmp(name, de->name, len);223}224 225/*226 * p is at least 6 bytes before the end of page227 */228static struct nilfs_dir_entry *nilfs_next_entry(struct nilfs_dir_entry *p)229{230 return (struct nilfs_dir_entry *)((char *)p +231 nilfs_rec_len_from_disk(p->rec_len));232}233 234static int nilfs_readdir(struct file *file, struct dir_context *ctx)235{236 loff_t pos = ctx->pos;237 struct inode *inode = file_inode(file);238 struct super_block *sb = inode->i_sb;239 unsigned int offset = pos & ~PAGE_MASK;240 unsigned long n = pos >> PAGE_SHIFT;241 unsigned long npages = dir_pages(inode);242 243 if (pos > inode->i_size - NILFS_DIR_REC_LEN(1))244 return 0;245 246 for ( ; n < npages; n++, offset = 0) {247 char *kaddr, *limit;248 struct nilfs_dir_entry *de;249 struct folio *folio;250 251 kaddr = nilfs_get_folio(inode, n, &folio);252 if (IS_ERR(kaddr)) {253 nilfs_error(sb, "bad page in #%lu", inode->i_ino);254 ctx->pos += PAGE_SIZE - offset;255 return -EIO;256 }257 de = (struct nilfs_dir_entry *)(kaddr + offset);258 limit = kaddr + nilfs_last_byte(inode, n) -259 NILFS_DIR_REC_LEN(1);260 for ( ; (char *)de <= limit; de = nilfs_next_entry(de)) {261 if (de->rec_len == 0) {262 nilfs_error(sb, "zero-length directory entry");263 folio_release_kmap(folio, kaddr);264 return -EIO;265 }266 if (de->inode) {267 unsigned char t;268 269 t = fs_ftype_to_dtype(de->file_type);270 271 if (!dir_emit(ctx, de->name, de->name_len,272 le64_to_cpu(de->inode), t)) {273 folio_release_kmap(folio, kaddr);274 return 0;275 }276 }277 ctx->pos += nilfs_rec_len_from_disk(de->rec_len);278 }279 folio_release_kmap(folio, kaddr);280 }281 return 0;282}283 284/*285 * nilfs_find_entry()286 *287 * Finds an entry in the specified directory with the wanted name. It288 * returns the folio in which the entry was found, and the entry itself.289 * The folio is mapped and unlocked. When the caller is finished with290 * the entry, it should call folio_release_kmap().291 *292 * On failure, returns an error pointer and the caller should ignore foliop.293 */294struct nilfs_dir_entry *nilfs_find_entry(struct inode *dir,295 const struct qstr *qstr, struct folio **foliop)296{297 const unsigned char *name = qstr->name;298 int namelen = qstr->len;299 unsigned int reclen = NILFS_DIR_REC_LEN(namelen);300 unsigned long start, n;301 unsigned long npages = dir_pages(dir);302 struct nilfs_inode_info *ei = NILFS_I(dir);303 struct nilfs_dir_entry *de;304 305 if (npages == 0)306 goto out;307 308 start = ei->i_dir_start_lookup;309 if (start >= npages)310 start = 0;311 n = start;312 do {313 char *kaddr = nilfs_get_folio(dir, n, foliop);314 315 if (IS_ERR(kaddr))316 return ERR_CAST(kaddr);317 318 de = (struct nilfs_dir_entry *)kaddr;319 kaddr += nilfs_last_byte(dir, n) - reclen;320 while ((char *)de <= kaddr) {321 if (de->rec_len == 0) {322 nilfs_error(dir->i_sb,323 "zero-length directory entry");324 folio_release_kmap(*foliop, kaddr);325 goto out;326 }327 if (nilfs_match(namelen, name, de))328 goto found;329 de = nilfs_next_entry(de);330 }331 folio_release_kmap(*foliop, kaddr);332 333 if (++n >= npages)334 n = 0;335 /* next folio is past the blocks we've got */336 if (unlikely(n > (dir->i_blocks >> (PAGE_SHIFT - 9)))) {337 nilfs_error(dir->i_sb,338 "dir %lu size %lld exceeds block count %llu",339 dir->i_ino, dir->i_size,340 (unsigned long long)dir->i_blocks);341 goto out;342 }343 } while (n != start);344out:345 return ERR_PTR(-ENOENT);346 347found:348 ei->i_dir_start_lookup = n;349 return de;350}351 352struct nilfs_dir_entry *nilfs_dotdot(struct inode *dir, struct folio **foliop)353{354 struct folio *folio;355 struct nilfs_dir_entry *de, *next_de;356 size_t limit;357 char *msg;358 359 de = nilfs_get_folio(dir, 0, &folio);360 if (IS_ERR(de))361 return NULL;362 363 limit = nilfs_last_byte(dir, 0); /* is a multiple of chunk size */364 if (unlikely(!limit || le64_to_cpu(de->inode) != dir->i_ino ||365 !nilfs_match(1, ".", de))) {366 msg = "missing '.'";367 goto fail;368 }369 370 next_de = nilfs_next_entry(de);371 /*372 * If "next_de" has not reached the end of the chunk, there is373 * at least one more record. Check whether it matches "..".374 */375 if (unlikely((char *)next_de == (char *)de + nilfs_chunk_size(dir) ||376 !nilfs_match(2, "..", next_de))) {377 msg = "missing '..'";378 goto fail;379 }380 *foliop = folio;381 return next_de;382 383fail:384 nilfs_error(dir->i_sb, "directory #%lu %s", dir->i_ino, msg);385 folio_release_kmap(folio, de);386 return NULL;387}388 389int nilfs_inode_by_name(struct inode *dir, const struct qstr *qstr, ino_t *ino)390{391 struct nilfs_dir_entry *de;392 struct folio *folio;393 394 de = nilfs_find_entry(dir, qstr, &folio);395 if (IS_ERR(de))396 return PTR_ERR(de);397 398 *ino = le64_to_cpu(de->inode);399 folio_release_kmap(folio, de);400 return 0;401}402 403void nilfs_set_link(struct inode *dir, struct nilfs_dir_entry *de,404 struct folio *folio, struct inode *inode)405{406 size_t from = offset_in_folio(folio, de);407 size_t to = from + nilfs_rec_len_from_disk(de->rec_len);408 struct address_space *mapping = folio->mapping;409 int err;410 411 folio_lock(folio);412 err = nilfs_prepare_chunk(folio, from, to);413 BUG_ON(err);414 de->inode = cpu_to_le64(inode->i_ino);415 de->file_type = fs_umode_to_ftype(inode->i_mode);416 nilfs_commit_chunk(folio, mapping, from, to);417 inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));418}419 420/*421 * Parent is locked.422 */423int nilfs_add_link(struct dentry *dentry, struct inode *inode)424{425 struct inode *dir = d_inode(dentry->d_parent);426 const unsigned char *name = dentry->d_name.name;427 int namelen = dentry->d_name.len;428 unsigned int chunk_size = nilfs_chunk_size(dir);429 unsigned int reclen = NILFS_DIR_REC_LEN(namelen);430 unsigned short rec_len, name_len;431 struct folio *folio = NULL;432 struct nilfs_dir_entry *de;433 unsigned long npages = dir_pages(dir);434 unsigned long n;435 size_t from, to;436 int err;437 438 /*439 * We take care of directory expansion in the same loop.440 * This code plays outside i_size, so it locks the folio441 * to protect that region.442 */443 for (n = 0; n <= npages; n++) {444 char *kaddr = nilfs_get_folio(dir, n, &folio);445 char *dir_end;446 447 if (IS_ERR(kaddr))448 return PTR_ERR(kaddr);449 folio_lock(folio);450 dir_end = kaddr + nilfs_last_byte(dir, n);451 de = (struct nilfs_dir_entry *)kaddr;452 kaddr += folio_size(folio) - reclen;453 while ((char *)de <= kaddr) {454 if ((char *)de == dir_end) {455 /* We hit i_size */456 name_len = 0;457 rec_len = chunk_size;458 de->rec_len = nilfs_rec_len_to_disk(chunk_size);459 de->inode = 0;460 goto got_it;461 }462 if (de->rec_len == 0) {463 nilfs_error(dir->i_sb,464 "zero-length directory entry");465 err = -EIO;466 goto out_unlock;467 }468 err = -EEXIST;469 if (nilfs_match(namelen, name, de))470 goto out_unlock;471 name_len = NILFS_DIR_REC_LEN(de->name_len);472 rec_len = nilfs_rec_len_from_disk(de->rec_len);473 if (!de->inode && rec_len >= reclen)474 goto got_it;475 if (rec_len >= name_len + reclen)476 goto got_it;477 de = (struct nilfs_dir_entry *)((char *)de + rec_len);478 }479 folio_unlock(folio);480 folio_release_kmap(folio, kaddr);481 }482 BUG();483 return -EINVAL;484 485got_it:486 from = offset_in_folio(folio, de);487 to = from + rec_len;488 err = nilfs_prepare_chunk(folio, from, to);489 if (err)490 goto out_unlock;491 if (de->inode) {492 struct nilfs_dir_entry *de1;493 494 de1 = (struct nilfs_dir_entry *)((char *)de + name_len);495 de1->rec_len = nilfs_rec_len_to_disk(rec_len - name_len);496 de->rec_len = nilfs_rec_len_to_disk(name_len);497 de = de1;498 }499 de->name_len = namelen;500 memcpy(de->name, name, namelen);501 de->inode = cpu_to_le64(inode->i_ino);502 de->file_type = fs_umode_to_ftype(inode->i_mode);503 nilfs_commit_chunk(folio, folio->mapping, from, to);504 inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));505 nilfs_mark_inode_dirty(dir);506 /* OFFSET_CACHE */507out_put:508 folio_release_kmap(folio, de);509 return err;510out_unlock:511 folio_unlock(folio);512 goto out_put;513}514 515/*516 * nilfs_delete_entry deletes a directory entry by merging it with the517 * previous entry. Folio is up-to-date.518 */519int nilfs_delete_entry(struct nilfs_dir_entry *dir, struct folio *folio)520{521 struct address_space *mapping = folio->mapping;522 struct inode *inode = mapping->host;523 char *kaddr = (char *)((unsigned long)dir & ~(folio_size(folio) - 1));524 size_t from, to;525 struct nilfs_dir_entry *de, *pde = NULL;526 int err;527 528 from = ((char *)dir - kaddr) & ~(nilfs_chunk_size(inode) - 1);529 to = ((char *)dir - kaddr) + nilfs_rec_len_from_disk(dir->rec_len);530 de = (struct nilfs_dir_entry *)(kaddr + from);531 532 while ((char *)de < (char *)dir) {533 if (de->rec_len == 0) {534 nilfs_error(inode->i_sb,535 "zero-length directory entry");536 err = -EIO;537 goto out;538 }539 pde = de;540 de = nilfs_next_entry(de);541 }542 if (pde)543 from = (char *)pde - kaddr;544 folio_lock(folio);545 err = nilfs_prepare_chunk(folio, from, to);546 BUG_ON(err);547 if (pde)548 pde->rec_len = nilfs_rec_len_to_disk(to - from);549 dir->inode = 0;550 nilfs_commit_chunk(folio, mapping, from, to);551 inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));552out:553 return err;554}555 556/*557 * Set the first fragment of directory.558 */559int nilfs_make_empty(struct inode *inode, struct inode *parent)560{561 struct address_space *mapping = inode->i_mapping;562 struct folio *folio = filemap_grab_folio(mapping, 0);563 unsigned int chunk_size = nilfs_chunk_size(inode);564 struct nilfs_dir_entry *de;565 int err;566 void *kaddr;567 568 if (IS_ERR(folio))569 return PTR_ERR(folio);570 571 err = nilfs_prepare_chunk(folio, 0, chunk_size);572 if (unlikely(err)) {573 folio_unlock(folio);574 goto fail;575 }576 kaddr = kmap_local_folio(folio, 0);577 memset(kaddr, 0, chunk_size);578 de = (struct nilfs_dir_entry *)kaddr;579 de->name_len = 1;580 de->rec_len = nilfs_rec_len_to_disk(NILFS_DIR_REC_LEN(1));581 memcpy(de->name, ".\0\0", 4);582 de->inode = cpu_to_le64(inode->i_ino);583 de->file_type = fs_umode_to_ftype(inode->i_mode);584 585 de = (struct nilfs_dir_entry *)(kaddr + NILFS_DIR_REC_LEN(1));586 de->name_len = 2;587 de->rec_len = nilfs_rec_len_to_disk(chunk_size - NILFS_DIR_REC_LEN(1));588 de->inode = cpu_to_le64(parent->i_ino);589 memcpy(de->name, "..\0", 4);590 de->file_type = fs_umode_to_ftype(inode->i_mode);591 kunmap_local(kaddr);592 nilfs_commit_chunk(folio, mapping, 0, chunk_size);593fail:594 folio_put(folio);595 return err;596}597 598/*599 * routine to check that the specified directory is empty (for rmdir)600 */601int nilfs_empty_dir(struct inode *inode)602{603 struct folio *folio = NULL;604 char *kaddr;605 unsigned long i, npages = dir_pages(inode);606 607 for (i = 0; i < npages; i++) {608 struct nilfs_dir_entry *de;609 610 kaddr = nilfs_get_folio(inode, i, &folio);611 if (IS_ERR(kaddr))612 return 0;613 614 de = (struct nilfs_dir_entry *)kaddr;615 kaddr += nilfs_last_byte(inode, i) - NILFS_DIR_REC_LEN(1);616 617 while ((char *)de <= kaddr) {618 if (de->rec_len == 0) {619 nilfs_error(inode->i_sb,620 "zero-length directory entry (kaddr=%p, de=%p)",621 kaddr, de);622 goto not_empty;623 }624 if (de->inode != 0) {625 /* check for . and .. */626 if (de->name[0] != '.')627 goto not_empty;628 if (de->name_len > 2)629 goto not_empty;630 if (de->name_len < 2) {631 if (de->inode !=632 cpu_to_le64(inode->i_ino))633 goto not_empty;634 } else if (de->name[1] != '.')635 goto not_empty;636 }637 de = nilfs_next_entry(de);638 }639 folio_release_kmap(folio, kaddr);640 }641 return 1;642 643not_empty:644 folio_release_kmap(folio, kaddr);645 return 0;646}647 648const struct file_operations nilfs_dir_operations = {649 .llseek = generic_file_llseek,650 .read = generic_read_dir,651 .iterate_shared = nilfs_readdir,652 .unlocked_ioctl = nilfs_ioctl,653#ifdef CONFIG_COMPAT654 .compat_ioctl = nilfs_compat_ioctl,655#endif /* CONFIG_COMPAT */656 .fsync = nilfs_sync_file,657 658};659