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1// SPDX-License-Identifier: GPL-2.02/*3 * linux/fs/ext2/dir.c4 *5 * Copyright (C) 1992, 1993, 1994, 19956 * Remy Card (card@masi.ibp.fr)7 * Laboratoire MASI - Institut Blaise Pascal8 * Universite Pierre et Marie Curie (Paris VI)9 *10 * from11 *12 * linux/fs/minix/dir.c13 *14 * Copyright (C) 1991, 1992 Linus Torvalds15 *16 * ext2 directory handling functions17 *18 * Big-endian to little-endian byte-swapping/bitmaps by19 * David S. Miller (davem@caip.rutgers.edu), 199520 *21 * All code that works with directory layout had been switched to pagecache22 * and moved here. AV23 */24 25#include "ext2.h"26#include <linux/buffer_head.h>27#include <linux/pagemap.h>28#include <linux/swap.h>29#include <linux/iversion.h>30 31typedef struct ext2_dir_entry_2 ext2_dirent;32 33/*34 * Tests against MAX_REC_LEN etc were put in place for 64k block35 * sizes; if that is not possible on this arch, we can skip36 * those tests and speed things up.37 */38static inline unsigned ext2_rec_len_from_disk(__le16 dlen)39{40 unsigned len = le16_to_cpu(dlen);41 42#if (PAGE_SIZE >= 65536)43 if (len == EXT2_MAX_REC_LEN)44 return 1 << 16;45#endif46 return len;47}48 49static inline __le16 ext2_rec_len_to_disk(unsigned len)50{51#if (PAGE_SIZE >= 65536)52 if (len == (1 << 16))53 return cpu_to_le16(EXT2_MAX_REC_LEN);54 else55 BUG_ON(len > (1 << 16));56#endif57 return cpu_to_le16(len);58}59 60/*61 * ext2 uses block-sized chunks. Arguably, sector-sized ones would be62 * more robust, but we have what we have63 */64static inline unsigned ext2_chunk_size(struct inode *inode)65{66 return inode->i_sb->s_blocksize;67}68 69/*70 * Return the offset into page `page_nr' of the last valid71 * byte in that page, plus one.72 */73static unsigned74ext2_last_byte(struct inode *inode, unsigned long page_nr)75{76 unsigned last_byte = inode->i_size;77 78 last_byte -= page_nr << PAGE_SHIFT;79 if (last_byte > PAGE_SIZE)80 last_byte = PAGE_SIZE;81 return last_byte;82}83 84static void ext2_commit_chunk(struct folio *folio, loff_t pos, unsigned len)85{86 struct address_space *mapping = folio->mapping;87 struct inode *dir = mapping->host;88 89 inode_inc_iversion(dir);90 block_write_end(NULL, mapping, pos, len, len, folio, NULL);91 92 if (pos+len > dir->i_size) {93 i_size_write(dir, pos+len);94 mark_inode_dirty(dir);95 }96 folio_unlock(folio);97}98 99static bool ext2_check_folio(struct folio *folio, int quiet, char *kaddr)100{101 struct inode *dir = folio->mapping->host;102 struct super_block *sb = dir->i_sb;103 unsigned chunk_size = ext2_chunk_size(dir);104 u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);105 unsigned offs, rec_len;106 unsigned limit = folio_size(folio);107 ext2_dirent *p;108 char *error;109 110 if (dir->i_size < folio_pos(folio) + limit) {111 limit = offset_in_folio(folio, dir->i_size);112 if (limit & (chunk_size - 1))113 goto Ebadsize;114 if (!limit)115 goto out;116 }117 for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {118 p = (ext2_dirent *)(kaddr + offs);119 rec_len = ext2_rec_len_from_disk(p->rec_len);120 121 if (unlikely(rec_len < EXT2_DIR_REC_LEN(1)))122 goto Eshort;123 if (unlikely(rec_len & 3))124 goto Ealign;125 if (unlikely(rec_len < EXT2_DIR_REC_LEN(p->name_len)))126 goto Enamelen;127 if (unlikely(((offs + rec_len - 1) ^ offs) & ~(chunk_size-1)))128 goto Espan;129 if (unlikely(le32_to_cpu(p->inode) > max_inumber))130 goto Einumber;131 }132 if (offs != limit)133 goto Eend;134out:135 folio_set_checked(folio);136 return true;137 138 /* Too bad, we had an error */139 140Ebadsize:141 if (!quiet)142 ext2_error(sb, __func__,143 "size of directory #%lu is not a multiple "144 "of chunk size", dir->i_ino);145 goto fail;146Eshort:147 error = "rec_len is smaller than minimal";148 goto bad_entry;149Ealign:150 error = "unaligned directory entry";151 goto bad_entry;152Enamelen:153 error = "rec_len is too small for name_len";154 goto bad_entry;155Espan:156 error = "directory entry across blocks";157 goto bad_entry;158Einumber:159 error = "inode out of bounds";160bad_entry:161 if (!quiet)162 ext2_error(sb, __func__, "bad entry in directory #%lu: : %s - "163 "offset=%llu, inode=%lu, rec_len=%d, name_len=%d",164 dir->i_ino, error, folio_pos(folio) + offs,165 (unsigned long) le32_to_cpu(p->inode),166 rec_len, p->name_len);167 goto fail;168Eend:169 if (!quiet) {170 p = (ext2_dirent *)(kaddr + offs);171 ext2_error(sb, "ext2_check_folio",172 "entry in directory #%lu spans the page boundary"173 "offset=%llu, inode=%lu",174 dir->i_ino, folio_pos(folio) + offs,175 (unsigned long) le32_to_cpu(p->inode));176 }177fail:178 return false;179}180 181/*182 * Calls to ext2_get_folio()/folio_release_kmap() must be nested according183 * to the rules documented in kmap_local_folio()/kunmap_local().184 *185 * NOTE: ext2_find_entry() and ext2_dotdot() act as a call186 * to folio_release_kmap() and should be treated as a call to187 * folio_release_kmap() for nesting purposes.188 */189static void *ext2_get_folio(struct inode *dir, unsigned long n,190 int quiet, struct folio **foliop)191{192 struct address_space *mapping = dir->i_mapping;193 struct folio *folio = read_mapping_folio(mapping, n, NULL);194 void *kaddr;195 196 if (IS_ERR(folio))197 return ERR_CAST(folio);198 kaddr = kmap_local_folio(folio, 0);199 if (unlikely(!folio_test_checked(folio))) {200 if (!ext2_check_folio(folio, quiet, kaddr))201 goto fail;202 }203 *foliop = folio;204 return kaddr;205 206fail:207 folio_release_kmap(folio, kaddr);208 return ERR_PTR(-EIO);209}210 211/*212 * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.213 *214 * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.215 */216static inline int ext2_match (int len, const char * const name,217 struct ext2_dir_entry_2 * de)218{219 if (len != de->name_len)220 return 0;221 if (!de->inode)222 return 0;223 return !memcmp(name, de->name, len);224}225 226/*227 * p is at least 6 bytes before the end of page228 */229static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)230{231 return (ext2_dirent *)((char *)p +232 ext2_rec_len_from_disk(p->rec_len));233}234 235static inline unsigned 236ext2_validate_entry(char *base, unsigned offset, unsigned mask)237{238 ext2_dirent *de = (ext2_dirent*)(base + offset);239 ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));240 while ((char*)p < (char*)de) {241 if (p->rec_len == 0)242 break;243 p = ext2_next_entry(p);244 }245 return offset_in_page(p);246}247 248static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)249{250 if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))251 de->file_type = fs_umode_to_ftype(inode->i_mode);252 else253 de->file_type = 0;254}255 256static int257ext2_readdir(struct file *file, struct dir_context *ctx)258{259 loff_t pos = ctx->pos;260 struct inode *inode = file_inode(file);261 struct super_block *sb = inode->i_sb;262 unsigned int offset = pos & ~PAGE_MASK;263 unsigned long n = pos >> PAGE_SHIFT;264 unsigned long npages = dir_pages(inode);265 unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);266 bool need_revalidate = !inode_eq_iversion(inode, *(u64 *)file->private_data);267 bool has_filetype;268 269 if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))270 return 0;271 272 has_filetype =273 EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE);274 275 for ( ; n < npages; n++, offset = 0) {276 ext2_dirent *de;277 struct folio *folio;278 char *kaddr = ext2_get_folio(inode, n, 0, &folio);279 char *limit;280 281 if (IS_ERR(kaddr)) {282 ext2_error(sb, __func__,283 "bad page in #%lu",284 inode->i_ino);285 ctx->pos += PAGE_SIZE - offset;286 return PTR_ERR(kaddr);287 }288 if (unlikely(need_revalidate)) {289 if (offset) {290 offset = ext2_validate_entry(kaddr, offset, chunk_mask);291 ctx->pos = (n<<PAGE_SHIFT) + offset;292 }293 *(u64 *)file->private_data = inode_query_iversion(inode);294 need_revalidate = false;295 }296 de = (ext2_dirent *)(kaddr+offset);297 limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);298 for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {299 if (de->rec_len == 0) {300 ext2_error(sb, __func__,301 "zero-length directory entry");302 folio_release_kmap(folio, de);303 return -EIO;304 }305 if (de->inode) {306 unsigned char d_type = DT_UNKNOWN;307 308 if (has_filetype)309 d_type = fs_ftype_to_dtype(de->file_type);310 311 if (!dir_emit(ctx, de->name, de->name_len,312 le32_to_cpu(de->inode),313 d_type)) {314 folio_release_kmap(folio, de);315 return 0;316 }317 }318 ctx->pos += ext2_rec_len_from_disk(de->rec_len);319 }320 folio_release_kmap(folio, kaddr);321 }322 return 0;323}324 325/*326 * ext2_find_entry()327 *328 * finds an entry in the specified directory with the wanted name. It329 * returns the page in which the entry was found (as a parameter - res_page),330 * and the entry itself. Page is returned mapped and unlocked.331 * Entry is guaranteed to be valid.332 *333 * On Success folio_release_kmap() should be called on *foliop.334 *335 * NOTE: Calls to ext2_get_folio()/folio_release_kmap() must be nested336 * according to the rules documented in kmap_local_folio()/kunmap_local().337 *338 * ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_folio()339 * and should be treated as a call to ext2_get_folio() for nesting340 * purposes.341 */342struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,343 const struct qstr *child, struct folio **foliop)344{345 const char *name = child->name;346 int namelen = child->len;347 unsigned reclen = EXT2_DIR_REC_LEN(namelen);348 unsigned long start, n;349 unsigned long npages = dir_pages(dir);350 struct ext2_inode_info *ei = EXT2_I(dir);351 ext2_dirent * de;352 353 if (npages == 0)354 goto out;355 356 start = ei->i_dir_start_lookup;357 if (start >= npages)358 start = 0;359 n = start;360 do {361 char *kaddr = ext2_get_folio(dir, n, 0, foliop);362 if (IS_ERR(kaddr))363 return ERR_CAST(kaddr);364 365 de = (ext2_dirent *) kaddr;366 kaddr += ext2_last_byte(dir, n) - reclen;367 while ((char *) de <= kaddr) {368 if (de->rec_len == 0) {369 ext2_error(dir->i_sb, __func__,370 "zero-length directory entry");371 folio_release_kmap(*foliop, de);372 goto out;373 }374 if (ext2_match(namelen, name, de))375 goto found;376 de = ext2_next_entry(de);377 }378 folio_release_kmap(*foliop, kaddr);379 380 if (++n >= npages)381 n = 0;382 /* next folio is past the blocks we've got */383 if (unlikely(n > (dir->i_blocks >> (PAGE_SHIFT - 9)))) {384 ext2_error(dir->i_sb, __func__,385 "dir %lu size %lld exceeds block count %llu",386 dir->i_ino, dir->i_size,387 (unsigned long long)dir->i_blocks);388 goto out;389 }390 } while (n != start);391out:392 return ERR_PTR(-ENOENT);393 394found:395 ei->i_dir_start_lookup = n;396 return de;397}398 399/*400 * Return the '..' directory entry and the page in which the entry was found401 * (as a parameter - p).402 *403 * On Success folio_release_kmap() should be called on *foliop.404 *405 * NOTE: Calls to ext2_get_folio()/folio_release_kmap() must be nested406 * according to the rules documented in kmap_local_folio()/kunmap_local().407 *408 * ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_folio()409 * and should be treated as a call to ext2_get_folio() for nesting410 * purposes.411 */412struct ext2_dir_entry_2 *ext2_dotdot(struct inode *dir, struct folio **foliop)413{414 ext2_dirent *de = ext2_get_folio(dir, 0, 0, foliop);415 416 if (!IS_ERR(de))417 return ext2_next_entry(de);418 return NULL;419}420 421int ext2_inode_by_name(struct inode *dir, const struct qstr *child, ino_t *ino)422{423 struct ext2_dir_entry_2 *de;424 struct folio *folio;425 426 de = ext2_find_entry(dir, child, &folio);427 if (IS_ERR(de))428 return PTR_ERR(de);429 430 *ino = le32_to_cpu(de->inode);431 folio_release_kmap(folio, de);432 return 0;433}434 435static int ext2_prepare_chunk(struct folio *folio, loff_t pos, unsigned len)436{437 return __block_write_begin(folio, pos, len, ext2_get_block);438}439 440static int ext2_handle_dirsync(struct inode *dir)441{442 int err;443 444 err = filemap_write_and_wait(dir->i_mapping);445 if (!err)446 err = sync_inode_metadata(dir, 1);447 return err;448}449 450int ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,451 struct folio *folio, struct inode *inode, bool update_times)452{453 loff_t pos = folio_pos(folio) + offset_in_folio(folio, de);454 unsigned len = ext2_rec_len_from_disk(de->rec_len);455 int err;456 457 folio_lock(folio);458 err = ext2_prepare_chunk(folio, pos, len);459 if (err) {460 folio_unlock(folio);461 return err;462 }463 de->inode = cpu_to_le32(inode->i_ino);464 ext2_set_de_type(de, inode);465 ext2_commit_chunk(folio, pos, len);466 if (update_times)467 inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));468 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;469 mark_inode_dirty(dir);470 return ext2_handle_dirsync(dir);471}472 473/*474 * Parent is locked.475 */476int ext2_add_link (struct dentry *dentry, struct inode *inode)477{478 struct inode *dir = d_inode(dentry->d_parent);479 const char *name = dentry->d_name.name;480 int namelen = dentry->d_name.len;481 unsigned chunk_size = ext2_chunk_size(dir);482 unsigned reclen = EXT2_DIR_REC_LEN(namelen);483 unsigned short rec_len, name_len;484 struct folio *folio = NULL;485 ext2_dirent * de;486 unsigned long npages = dir_pages(dir);487 unsigned long n;488 loff_t pos;489 int err;490 491 /*492 * We take care of directory expansion in the same loop.493 * This code plays outside i_size, so it locks the folio494 * to protect that region.495 */496 for (n = 0; n <= npages; n++) {497 char *kaddr = ext2_get_folio(dir, n, 0, &folio);498 char *dir_end;499 500 if (IS_ERR(kaddr))501 return PTR_ERR(kaddr);502 folio_lock(folio);503 dir_end = kaddr + ext2_last_byte(dir, n);504 de = (ext2_dirent *)kaddr;505 kaddr += folio_size(folio) - reclen;506 while ((char *)de <= kaddr) {507 if ((char *)de == dir_end) {508 /* We hit i_size */509 name_len = 0;510 rec_len = chunk_size;511 de->rec_len = ext2_rec_len_to_disk(chunk_size);512 de->inode = 0;513 goto got_it;514 }515 if (de->rec_len == 0) {516 ext2_error(dir->i_sb, __func__,517 "zero-length directory entry");518 err = -EIO;519 goto out_unlock;520 }521 err = -EEXIST;522 if (ext2_match (namelen, name, de))523 goto out_unlock;524 name_len = EXT2_DIR_REC_LEN(de->name_len);525 rec_len = ext2_rec_len_from_disk(de->rec_len);526 if (!de->inode && rec_len >= reclen)527 goto got_it;528 if (rec_len >= name_len + reclen)529 goto got_it;530 de = (ext2_dirent *) ((char *) de + rec_len);531 }532 folio_unlock(folio);533 folio_release_kmap(folio, kaddr);534 }535 BUG();536 return -EINVAL;537 538got_it:539 pos = folio_pos(folio) + offset_in_folio(folio, de);540 err = ext2_prepare_chunk(folio, pos, rec_len);541 if (err)542 goto out_unlock;543 if (de->inode) {544 ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);545 de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);546 de->rec_len = ext2_rec_len_to_disk(name_len);547 de = de1;548 }549 de->name_len = namelen;550 memcpy(de->name, name, namelen);551 de->inode = cpu_to_le32(inode->i_ino);552 ext2_set_de_type (de, inode);553 ext2_commit_chunk(folio, pos, rec_len);554 inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));555 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;556 mark_inode_dirty(dir);557 err = ext2_handle_dirsync(dir);558 /* OFFSET_CACHE */559out_put:560 folio_release_kmap(folio, de);561 return err;562out_unlock:563 folio_unlock(folio);564 goto out_put;565}566 567/*568 * ext2_delete_entry deletes a directory entry by merging it with the569 * previous entry. Page is up-to-date.570 */571int ext2_delete_entry(struct ext2_dir_entry_2 *dir, struct folio *folio)572{573 struct inode *inode = folio->mapping->host;574 size_t from, to;575 char *kaddr;576 loff_t pos;577 ext2_dirent *de, *pde = NULL;578 int err;579 580 from = offset_in_folio(folio, dir);581 to = from + ext2_rec_len_from_disk(dir->rec_len);582 kaddr = (char *)dir - from;583 from &= ~(ext2_chunk_size(inode)-1);584 de = (ext2_dirent *)(kaddr + from);585 586 while ((char*)de < (char*)dir) {587 if (de->rec_len == 0) {588 ext2_error(inode->i_sb, __func__,589 "zero-length directory entry");590 return -EIO;591 }592 pde = de;593 de = ext2_next_entry(de);594 }595 if (pde)596 from = offset_in_folio(folio, pde);597 pos = folio_pos(folio) + from;598 folio_lock(folio);599 err = ext2_prepare_chunk(folio, pos, to - from);600 if (err) {601 folio_unlock(folio);602 return err;603 }604 if (pde)605 pde->rec_len = ext2_rec_len_to_disk(to - from);606 dir->inode = 0;607 ext2_commit_chunk(folio, pos, to - from);608 inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));609 EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;610 mark_inode_dirty(inode);611 return ext2_handle_dirsync(inode);612}613 614/*615 * Set the first fragment of directory.616 */617int ext2_make_empty(struct inode *inode, struct inode *parent)618{619 struct folio *folio = filemap_grab_folio(inode->i_mapping, 0);620 unsigned chunk_size = ext2_chunk_size(inode);621 struct ext2_dir_entry_2 * de;622 int err;623 void *kaddr;624 625 if (IS_ERR(folio))626 return PTR_ERR(folio);627 628 err = ext2_prepare_chunk(folio, 0, chunk_size);629 if (err) {630 folio_unlock(folio);631 goto fail;632 }633 kaddr = kmap_local_folio(folio, 0);634 memset(kaddr, 0, chunk_size);635 de = (struct ext2_dir_entry_2 *)kaddr;636 de->name_len = 1;637 de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1));638 memcpy (de->name, ".\0\0", 4);639 de->inode = cpu_to_le32(inode->i_ino);640 ext2_set_de_type (de, inode);641 642 de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));643 de->name_len = 2;644 de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1));645 de->inode = cpu_to_le32(parent->i_ino);646 memcpy (de->name, "..\0", 4);647 ext2_set_de_type (de, inode);648 kunmap_local(kaddr);649 ext2_commit_chunk(folio, 0, chunk_size);650 err = ext2_handle_dirsync(inode);651fail:652 folio_put(folio);653 return err;654}655 656/*657 * routine to check that the specified directory is empty (for rmdir)658 */659int ext2_empty_dir(struct inode *inode)660{661 struct folio *folio;662 char *kaddr;663 unsigned long i, npages = dir_pages(inode);664 665 for (i = 0; i < npages; i++) {666 ext2_dirent *de;667 668 kaddr = ext2_get_folio(inode, i, 0, &folio);669 if (IS_ERR(kaddr))670 return 0;671 672 de = (ext2_dirent *)kaddr;673 kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);674 675 while ((char *)de <= kaddr) {676 if (de->rec_len == 0) {677 ext2_error(inode->i_sb, __func__,678 "zero-length directory entry");679 printk("kaddr=%p, de=%p\n", kaddr, de);680 goto not_empty;681 }682 if (de->inode != 0) {683 /* check for . and .. */684 if (de->name[0] != '.')685 goto not_empty;686 if (de->name_len > 2)687 goto not_empty;688 if (de->name_len < 2) {689 if (de->inode !=690 cpu_to_le32(inode->i_ino))691 goto not_empty;692 } else if (de->name[1] != '.')693 goto not_empty;694 }695 de = ext2_next_entry(de);696 }697 folio_release_kmap(folio, kaddr);698 }699 return 1;700 701not_empty:702 folio_release_kmap(folio, kaddr);703 return 0;704}705 706static int ext2_dir_open(struct inode *inode, struct file *file)707{708 file->private_data = kzalloc(sizeof(u64), GFP_KERNEL);709 if (!file->private_data)710 return -ENOMEM;711 return 0;712}713 714static int ext2_dir_release(struct inode *inode, struct file *file)715{716 kfree(file->private_data);717 return 0;718}719 720static loff_t ext2_dir_llseek(struct file *file, loff_t offset, int whence)721{722 return generic_llseek_cookie(file, offset, whence,723 (u64 *)file->private_data);724}725 726const struct file_operations ext2_dir_operations = {727 .open = ext2_dir_open,728 .release = ext2_dir_release,729 .llseek = ext2_dir_llseek,730 .read = generic_read_dir,731 .iterate_shared = ext2_readdir,732 .unlocked_ioctl = ext2_ioctl,733#ifdef CONFIG_COMPAT734 .compat_ioctl = ext2_compat_ioctl,735#endif736 .fsync = ext2_fsync,737};738