1 // SPDX-License-Identifier: GPL-2.0-only
5 * Written 1992,1993 by Werner Almesberger
6 * VFAT extensions by Gordon Chaffee, merged with msdos fs by Henrik Storner
7 * Rewritten for the constant inumbers support by Al Viro
11 * Max Cohan: Fixed invalid FSINFO offset when info_sector is 0
14 #include <linux/module.h>
15 #include <linux/pagemap.h>
16 #include <linux/mpage.h>
17 #include <linux/vfs.h>
18 #include <linux/seq_file.h>
19 #include <linux/parser.h>
20 #include <linux/uio.h>
21 #include <linux/blkdev.h>
22 #include <linux/backing-dev.h>
23 #include <asm/unaligned.h>
24 #include <linux/random.h>
25 #include <linux/iversion.h>
28 #ifndef CONFIG_FAT_DEFAULT_IOCHARSET
29 /* if user don't select VFAT, this is undefined. */
30 #define CONFIG_FAT_DEFAULT_IOCHARSET ""
33 #define KB_IN_SECTORS 2
35 /* DOS dates from 1980/1/1 through 2107/12/31 */
36 #define FAT_DATE_MIN (0<<9 | 1<<5 | 1)
37 #define FAT_DATE_MAX (127<<9 | 12<<5 | 31)
38 #define FAT_TIME_MAX (23<<11 | 59<<5 | 29)
41 * A deserialized copy of the on-disk structure laid out in struct
44 struct fat_bios_param_block {
58 u32 fat32_root_cluster;
59 u16 fat32_info_sector;
64 static int fat_default_codepage = CONFIG_FAT_DEFAULT_CODEPAGE;
65 static char fat_default_iocharset[] = CONFIG_FAT_DEFAULT_IOCHARSET;
67 static struct fat_floppy_defaults {
69 unsigned sec_per_clus;
73 } floppy_defaults[] = {
75 .nr_sectors = 160 * KB_IN_SECTORS,
82 .nr_sectors = 180 * KB_IN_SECTORS,
89 .nr_sectors = 320 * KB_IN_SECTORS,
96 .nr_sectors = 360 * KB_IN_SECTORS,
104 int fat_add_cluster(struct inode *inode)
108 err = fat_alloc_clusters(inode, &cluster, 1);
111 /* FIXME: this cluster should be added after data of this
112 * cluster is writed */
113 err = fat_chain_add(inode, cluster, 1);
115 fat_free_clusters(inode, cluster);
119 static inline int __fat_get_block(struct inode *inode, sector_t iblock,
120 unsigned long *max_blocks,
121 struct buffer_head *bh_result, int create)
123 struct super_block *sb = inode->i_sb;
124 struct msdos_sb_info *sbi = MSDOS_SB(sb);
125 unsigned long mapped_blocks;
126 sector_t phys, last_block;
129 err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);
133 map_bh(bh_result, sb, phys);
134 *max_blocks = min(mapped_blocks, *max_blocks);
140 if (iblock != MSDOS_I(inode)->mmu_private >> sb->s_blocksize_bits) {
141 fat_fs_error(sb, "corrupted file size (i_pos %lld, %lld)",
142 MSDOS_I(inode)->i_pos, MSDOS_I(inode)->mmu_private);
146 last_block = inode->i_blocks >> (sb->s_blocksize_bits - 9);
147 offset = (unsigned long)iblock & (sbi->sec_per_clus - 1);
149 * allocate a cluster according to the following.
150 * 1) no more available blocks
151 * 2) not part of fallocate region
153 if (!offset && !(iblock < last_block)) {
154 /* TODO: multiple cluster allocation would be desirable. */
155 err = fat_add_cluster(inode);
159 /* available blocks on this cluster */
160 mapped_blocks = sbi->sec_per_clus - offset;
162 *max_blocks = min(mapped_blocks, *max_blocks);
163 MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;
165 err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create, false);
170 "invalid FAT chain (i_pos %lld, last_block %llu)",
171 MSDOS_I(inode)->i_pos,
172 (unsigned long long)last_block);
176 BUG_ON(*max_blocks != mapped_blocks);
177 set_buffer_new(bh_result);
178 map_bh(bh_result, sb, phys);
183 static int fat_get_block(struct inode *inode, sector_t iblock,
184 struct buffer_head *bh_result, int create)
186 struct super_block *sb = inode->i_sb;
187 unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
190 err = __fat_get_block(inode, iblock, &max_blocks, bh_result, create);
193 bh_result->b_size = max_blocks << sb->s_blocksize_bits;
197 static int fat_writepages(struct address_space *mapping,
198 struct writeback_control *wbc)
200 return mpage_writepages(mapping, wbc, fat_get_block);
203 static int fat_read_folio(struct file *file, struct folio *folio)
205 return mpage_read_folio(folio, fat_get_block);
208 static void fat_readahead(struct readahead_control *rac)
210 mpage_readahead(rac, fat_get_block);
213 static void fat_write_failed(struct address_space *mapping, loff_t to)
215 struct inode *inode = mapping->host;
217 if (to > inode->i_size) {
218 truncate_pagecache(inode, inode->i_size);
219 fat_truncate_blocks(inode, inode->i_size);
223 static int fat_write_begin(struct file *file, struct address_space *mapping,
224 loff_t pos, unsigned len,
225 struct page **pagep, void **fsdata)
230 err = cont_write_begin(file, mapping, pos, len,
231 pagep, fsdata, fat_get_block,
232 &MSDOS_I(mapping->host)->mmu_private);
234 fat_write_failed(mapping, pos + len);
238 static int fat_write_end(struct file *file, struct address_space *mapping,
239 loff_t pos, unsigned len, unsigned copied,
240 struct page *pagep, void *fsdata)
242 struct inode *inode = mapping->host;
244 err = generic_write_end(file, mapping, pos, len, copied, pagep, fsdata);
246 fat_write_failed(mapping, pos + len);
247 if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
248 fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
249 MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
250 mark_inode_dirty(inode);
255 static ssize_t fat_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
257 struct file *file = iocb->ki_filp;
258 struct address_space *mapping = file->f_mapping;
259 struct inode *inode = mapping->host;
260 size_t count = iov_iter_count(iter);
261 loff_t offset = iocb->ki_pos;
264 if (iov_iter_rw(iter) == WRITE) {
266 * FIXME: blockdev_direct_IO() doesn't use ->write_begin(),
267 * so we need to update the ->mmu_private to block boundary.
269 * But we must fill the remaining area or hole by nul for
270 * updating ->mmu_private.
272 * Return 0, and fallback to normal buffered write.
274 loff_t size = offset + count;
275 if (MSDOS_I(inode)->mmu_private < size)
280 * FAT need to use the DIO_LOCKING for avoiding the race
281 * condition of fat_get_block() and ->truncate().
283 ret = blockdev_direct_IO(iocb, inode, iter, fat_get_block);
284 if (ret < 0 && iov_iter_rw(iter) == WRITE)
285 fat_write_failed(mapping, offset + count);
290 static int fat_get_block_bmap(struct inode *inode, sector_t iblock,
291 struct buffer_head *bh_result, int create)
293 struct super_block *sb = inode->i_sb;
294 unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
297 unsigned long mapped_blocks;
301 err = fat_bmap(inode, iblock, &bmap, &mapped_blocks, create, true);
306 map_bh(bh_result, sb, bmap);
307 max_blocks = min(mapped_blocks, max_blocks);
310 bh_result->b_size = max_blocks << sb->s_blocksize_bits;
315 static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
319 /* fat_get_cluster() assumes the requested blocknr isn't truncated. */
320 down_read(&MSDOS_I(mapping->host)->truncate_lock);
321 blocknr = generic_block_bmap(mapping, block, fat_get_block_bmap);
322 up_read(&MSDOS_I(mapping->host)->truncate_lock);
328 * fat_block_truncate_page() zeroes out a mapping from file offset `from'
329 * up to the end of the block which corresponds to `from'.
330 * This is required during truncate to physically zeroout the tail end
331 * of that block so it doesn't yield old data if the file is later grown.
332 * Also, avoid causing failure from fsx for cases of "data past EOF"
334 int fat_block_truncate_page(struct inode *inode, loff_t from)
336 return block_truncate_page(inode->i_mapping, from, fat_get_block);
339 static const struct address_space_operations fat_aops = {
340 .dirty_folio = block_dirty_folio,
341 .invalidate_folio = block_invalidate_folio,
342 .read_folio = fat_read_folio,
343 .readahead = fat_readahead,
344 .writepages = fat_writepages,
345 .write_begin = fat_write_begin,
346 .write_end = fat_write_end,
347 .direct_IO = fat_direct_IO,
349 .migrate_folio = buffer_migrate_folio,
353 * New FAT inode stuff. We do the following:
354 * a) i_ino is constant and has nothing with on-disk location.
355 * b) FAT manages its own cache of directory entries.
356 * c) *This* cache is indexed by on-disk location.
357 * d) inode has an associated directory entry, all right, but
358 * it may be unhashed.
359 * e) currently entries are stored within struct inode. That should
361 * f) we deal with races in the following way:
362 * 1. readdir() and lookup() do FAT-dir-cache lookup.
363 * 2. rename() unhashes the F-d-c entry and rehashes it in
365 * 3. unlink() and rmdir() unhash F-d-c entry.
366 * 4. fat_write_inode() checks whether the thing is unhashed.
367 * If it is we silently return. If it isn't we do bread(),
368 * check if the location is still valid and retry if it
369 * isn't. Otherwise we do changes.
370 * 5. Spinlock is used to protect hash/unhash/location check/lookup
371 * 6. fat_evict_inode() unhashes the F-d-c entry.
372 * 7. lookup() and readdir() do igrab() if they find a F-d-c entry
373 * and consider negative result as cache miss.
376 static void fat_hash_init(struct super_block *sb)
378 struct msdos_sb_info *sbi = MSDOS_SB(sb);
381 spin_lock_init(&sbi->inode_hash_lock);
382 for (i = 0; i < FAT_HASH_SIZE; i++)
383 INIT_HLIST_HEAD(&sbi->inode_hashtable[i]);
386 static inline unsigned long fat_hash(loff_t i_pos)
388 return hash_32(i_pos, FAT_HASH_BITS);
391 static void dir_hash_init(struct super_block *sb)
393 struct msdos_sb_info *sbi = MSDOS_SB(sb);
396 spin_lock_init(&sbi->dir_hash_lock);
397 for (i = 0; i < FAT_HASH_SIZE; i++)
398 INIT_HLIST_HEAD(&sbi->dir_hashtable[i]);
401 void fat_attach(struct inode *inode, loff_t i_pos)
403 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
405 if (inode->i_ino != MSDOS_ROOT_INO) {
406 struct hlist_head *head = sbi->inode_hashtable
409 spin_lock(&sbi->inode_hash_lock);
410 MSDOS_I(inode)->i_pos = i_pos;
411 hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
412 spin_unlock(&sbi->inode_hash_lock);
415 /* If NFS support is enabled, cache the mapping of start cluster
416 * to directory inode. This is used during reconnection of
417 * dentries to the filesystem root.
419 if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
420 struct hlist_head *d_head = sbi->dir_hashtable;
421 d_head += fat_dir_hash(MSDOS_I(inode)->i_logstart);
423 spin_lock(&sbi->dir_hash_lock);
424 hlist_add_head(&MSDOS_I(inode)->i_dir_hash, d_head);
425 spin_unlock(&sbi->dir_hash_lock);
428 EXPORT_SYMBOL_GPL(fat_attach);
430 void fat_detach(struct inode *inode)
432 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
433 spin_lock(&sbi->inode_hash_lock);
434 MSDOS_I(inode)->i_pos = 0;
435 hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
436 spin_unlock(&sbi->inode_hash_lock);
438 if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
439 spin_lock(&sbi->dir_hash_lock);
440 hlist_del_init(&MSDOS_I(inode)->i_dir_hash);
441 spin_unlock(&sbi->dir_hash_lock);
444 EXPORT_SYMBOL_GPL(fat_detach);
446 struct inode *fat_iget(struct super_block *sb, loff_t i_pos)
448 struct msdos_sb_info *sbi = MSDOS_SB(sb);
449 struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);
450 struct msdos_inode_info *i;
451 struct inode *inode = NULL;
453 spin_lock(&sbi->inode_hash_lock);
454 hlist_for_each_entry(i, head, i_fat_hash) {
455 BUG_ON(i->vfs_inode.i_sb != sb);
456 if (i->i_pos != i_pos)
458 inode = igrab(&i->vfs_inode);
462 spin_unlock(&sbi->inode_hash_lock);
466 static int is_exec(unsigned char *extension)
468 unsigned char exe_extensions[] = "EXECOMBAT", *walk;
470 for (walk = exe_extensions; *walk; walk += 3)
471 if (!strncmp(extension, walk, 3))
476 static int fat_calc_dir_size(struct inode *inode)
478 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
479 int ret, fclus, dclus;
482 if (MSDOS_I(inode)->i_start == 0)
485 ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
488 inode->i_size = (fclus + 1) << sbi->cluster_bits;
493 static int fat_validate_dir(struct inode *dir)
495 struct super_block *sb = dir->i_sb;
497 if (dir->i_nlink < 2) {
498 /* Directory should have "."/".." entries at least. */
499 fat_fs_error(sb, "corrupted directory (invalid entries)");
502 if (MSDOS_I(dir)->i_start == 0 ||
503 MSDOS_I(dir)->i_start == MSDOS_SB(sb)->root_cluster) {
504 /* Directory should point valid cluster. */
505 fat_fs_error(sb, "corrupted directory (invalid i_start)");
511 /* doesn't deal with root inode */
512 int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
514 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
515 struct timespec64 mtime;
518 MSDOS_I(inode)->i_pos = 0;
519 inode->i_uid = sbi->options.fs_uid;
520 inode->i_gid = sbi->options.fs_gid;
521 inode_inc_iversion(inode);
522 inode->i_generation = get_random_u32();
524 if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
525 inode->i_generation &= ~1;
526 inode->i_mode = fat_make_mode(sbi, de->attr, S_IRWXUGO);
527 inode->i_op = sbi->dir_ops;
528 inode->i_fop = &fat_dir_operations;
530 MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
531 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
532 error = fat_calc_dir_size(inode);
535 MSDOS_I(inode)->mmu_private = inode->i_size;
537 set_nlink(inode, fat_subdirs(inode));
539 error = fat_validate_dir(inode);
542 } else { /* not a directory */
543 inode->i_generation |= 1;
544 inode->i_mode = fat_make_mode(sbi, de->attr,
545 ((sbi->options.showexec && !is_exec(de->name + 8))
546 ? S_IRUGO|S_IWUGO : S_IRWXUGO));
547 MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
549 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
550 inode->i_size = le32_to_cpu(de->size);
551 inode->i_op = &fat_file_inode_operations;
552 inode->i_fop = &fat_file_operations;
553 inode->i_mapping->a_ops = &fat_aops;
554 MSDOS_I(inode)->mmu_private = inode->i_size;
556 if (de->attr & ATTR_SYS) {
557 if (sbi->options.sys_immutable)
558 inode->i_flags |= S_IMMUTABLE;
560 fat_save_attrs(inode, de->attr);
562 inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
563 & ~((loff_t)sbi->cluster_size - 1)) >> 9;
565 fat_time_fat2unix(sbi, &mtime, de->time, de->date, 0);
566 inode_set_mtime_to_ts(inode, mtime);
567 inode_set_ctime_to_ts(inode, mtime);
568 if (sbi->options.isvfat) {
569 struct timespec64 atime;
571 fat_time_fat2unix(sbi, &atime, 0, de->adate, 0);
572 inode_set_atime_to_ts(inode, atime);
573 fat_time_fat2unix(sbi, &MSDOS_I(inode)->i_crtime, de->ctime,
574 de->cdate, de->ctime_cs);
576 inode_set_atime_to_ts(inode, fat_truncate_atime(sbi, &mtime));
581 static inline void fat_lock_build_inode(struct msdos_sb_info *sbi)
583 if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
584 mutex_lock(&sbi->nfs_build_inode_lock);
587 static inline void fat_unlock_build_inode(struct msdos_sb_info *sbi)
589 if (sbi->options.nfs == FAT_NFS_NOSTALE_RO)
590 mutex_unlock(&sbi->nfs_build_inode_lock);
593 struct inode *fat_build_inode(struct super_block *sb,
594 struct msdos_dir_entry *de, loff_t i_pos)
599 fat_lock_build_inode(MSDOS_SB(sb));
600 inode = fat_iget(sb, i_pos);
603 inode = new_inode(sb);
605 inode = ERR_PTR(-ENOMEM);
608 inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
609 inode_set_iversion(inode, 1);
610 err = fat_fill_inode(inode, de);
613 inode = ERR_PTR(err);
616 fat_attach(inode, i_pos);
617 insert_inode_hash(inode);
619 fat_unlock_build_inode(MSDOS_SB(sb));
623 EXPORT_SYMBOL_GPL(fat_build_inode);
625 static int __fat_write_inode(struct inode *inode, int wait);
627 static void fat_free_eofblocks(struct inode *inode)
629 /* Release unwritten fallocated blocks on inode eviction. */
630 if ((inode->i_blocks << 9) >
631 round_up(MSDOS_I(inode)->mmu_private,
632 MSDOS_SB(inode->i_sb)->cluster_size)) {
635 fat_truncate_blocks(inode, MSDOS_I(inode)->mmu_private);
636 /* Fallocate results in updating the i_start/iogstart
637 * for the zero byte file. So, make it return to
638 * original state during evict and commit it to avoid
639 * any corruption on the next access to the cluster
640 * chain for the file.
642 err = __fat_write_inode(inode, inode_needs_sync(inode));
644 fat_msg(inode->i_sb, KERN_WARNING, "Failed to "
645 "update on disk inode for unused "
646 "fallocated blocks, inode could be "
647 "corrupted. Please run fsck");
653 static void fat_evict_inode(struct inode *inode)
655 truncate_inode_pages_final(&inode->i_data);
656 if (!inode->i_nlink) {
658 fat_truncate_blocks(inode, 0);
660 fat_free_eofblocks(inode);
662 invalidate_inode_buffers(inode);
664 fat_cache_inval_inode(inode);
668 static void fat_set_state(struct super_block *sb,
669 unsigned int set, unsigned int force)
671 struct buffer_head *bh;
672 struct fat_boot_sector *b;
673 struct msdos_sb_info *sbi = MSDOS_SB(sb);
675 /* do not change any thing if mounted read only */
676 if (sb_rdonly(sb) && !force)
679 /* do not change state if fs was dirty */
681 /* warn only on set (mount). */
683 fat_msg(sb, KERN_WARNING, "Volume was not properly "
684 "unmounted. Some data may be corrupt. "
689 bh = sb_bread(sb, 0);
691 fat_msg(sb, KERN_ERR, "unable to read boot sector "
692 "to mark fs as dirty");
696 b = (struct fat_boot_sector *) bh->b_data;
700 b->fat32.state |= FAT_STATE_DIRTY;
702 b->fat32.state &= ~FAT_STATE_DIRTY;
703 } else /* fat 16 and 12 */ {
705 b->fat16.state |= FAT_STATE_DIRTY;
707 b->fat16.state &= ~FAT_STATE_DIRTY;
710 mark_buffer_dirty(bh);
711 sync_dirty_buffer(bh);
715 static void fat_reset_iocharset(struct fat_mount_options *opts)
717 if (opts->iocharset != fat_default_iocharset) {
718 /* Note: opts->iocharset can be NULL here */
719 kfree(opts->iocharset);
720 opts->iocharset = fat_default_iocharset;
724 static void delayed_free(struct rcu_head *p)
726 struct msdos_sb_info *sbi = container_of(p, struct msdos_sb_info, rcu);
727 unload_nls(sbi->nls_disk);
728 unload_nls(sbi->nls_io);
729 fat_reset_iocharset(&sbi->options);
733 static void fat_put_super(struct super_block *sb)
735 struct msdos_sb_info *sbi = MSDOS_SB(sb);
737 fat_set_state(sb, 0, 0);
739 iput(sbi->fsinfo_inode);
740 iput(sbi->fat_inode);
742 call_rcu(&sbi->rcu, delayed_free);
745 static struct kmem_cache *fat_inode_cachep;
747 static struct inode *fat_alloc_inode(struct super_block *sb)
749 struct msdos_inode_info *ei;
750 ei = alloc_inode_sb(sb, fat_inode_cachep, GFP_NOFS);
754 init_rwsem(&ei->truncate_lock);
755 /* Zeroing to allow iput() even if partial initialized inode. */
761 ei->i_crtime.tv_sec = 0;
762 ei->i_crtime.tv_nsec = 0;
764 return &ei->vfs_inode;
767 static void fat_free_inode(struct inode *inode)
769 kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
772 static void init_once(void *foo)
774 struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;
776 spin_lock_init(&ei->cache_lru_lock);
778 ei->cache_valid_id = FAT_CACHE_VALID + 1;
779 INIT_LIST_HEAD(&ei->cache_lru);
780 INIT_HLIST_NODE(&ei->i_fat_hash);
781 INIT_HLIST_NODE(&ei->i_dir_hash);
782 inode_init_once(&ei->vfs_inode);
785 static int __init fat_init_inodecache(void)
787 fat_inode_cachep = kmem_cache_create("fat_inode_cache",
788 sizeof(struct msdos_inode_info),
789 0, (SLAB_RECLAIM_ACCOUNT|
790 SLAB_MEM_SPREAD|SLAB_ACCOUNT),
792 if (fat_inode_cachep == NULL)
797 static void __exit fat_destroy_inodecache(void)
800 * Make sure all delayed rcu free inodes are flushed before we
804 kmem_cache_destroy(fat_inode_cachep);
807 static int fat_remount(struct super_block *sb, int *flags, char *data)
810 struct msdos_sb_info *sbi = MSDOS_SB(sb);
811 *flags |= SB_NODIRATIME | (sbi->options.isvfat ? 0 : SB_NOATIME);
815 /* make sure we update state on remount. */
816 new_rdonly = *flags & SB_RDONLY;
817 if (new_rdonly != sb_rdonly(sb)) {
819 fat_set_state(sb, 0, 0);
821 fat_set_state(sb, 1, 1);
826 static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
828 struct super_block *sb = dentry->d_sb;
829 struct msdos_sb_info *sbi = MSDOS_SB(sb);
830 u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
832 /* If the count of free cluster is still unknown, counts it here. */
833 if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {
834 int err = fat_count_free_clusters(dentry->d_sb);
839 buf->f_type = dentry->d_sb->s_magic;
840 buf->f_bsize = sbi->cluster_size;
841 buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
842 buf->f_bfree = sbi->free_clusters;
843 buf->f_bavail = sbi->free_clusters;
844 buf->f_fsid = u64_to_fsid(id);
846 (sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;
851 static int __fat_write_inode(struct inode *inode, int wait)
853 struct super_block *sb = inode->i_sb;
854 struct msdos_sb_info *sbi = MSDOS_SB(sb);
855 struct buffer_head *bh;
856 struct msdos_dir_entry *raw_entry;
857 struct timespec64 mtime;
862 if (inode->i_ino == MSDOS_ROOT_INO)
866 i_pos = fat_i_pos_read(sbi, inode);
870 fat_get_blknr_offset(sbi, i_pos, &blocknr, &offset);
871 bh = sb_bread(sb, blocknr);
873 fat_msg(sb, KERN_ERR, "unable to read inode block "
874 "for updating (i_pos %lld)", i_pos);
877 spin_lock(&sbi->inode_hash_lock);
878 if (i_pos != MSDOS_I(inode)->i_pos) {
879 spin_unlock(&sbi->inode_hash_lock);
884 raw_entry = &((struct msdos_dir_entry *) (bh->b_data))[offset];
885 if (S_ISDIR(inode->i_mode))
888 raw_entry->size = cpu_to_le32(inode->i_size);
889 raw_entry->attr = fat_make_attrs(inode);
890 fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);
891 mtime = inode_get_mtime(inode);
892 fat_time_unix2fat(sbi, &mtime, &raw_entry->time,
893 &raw_entry->date, NULL);
894 if (sbi->options.isvfat) {
895 struct timespec64 ts = inode_get_atime(inode);
898 fat_time_unix2fat(sbi, &ts, &atime, &raw_entry->adate, NULL);
899 fat_time_unix2fat(sbi, &MSDOS_I(inode)->i_crtime, &raw_entry->ctime,
900 &raw_entry->cdate, &raw_entry->ctime_cs);
902 spin_unlock(&sbi->inode_hash_lock);
903 mark_buffer_dirty(bh);
906 err = sync_dirty_buffer(bh);
911 static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)
915 if (inode->i_ino == MSDOS_FSINFO_INO) {
916 struct super_block *sb = inode->i_sb;
918 mutex_lock(&MSDOS_SB(sb)->s_lock);
919 err = fat_clusters_flush(sb);
920 mutex_unlock(&MSDOS_SB(sb)->s_lock);
922 err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
927 int fat_sync_inode(struct inode *inode)
929 return __fat_write_inode(inode, 1);
932 EXPORT_SYMBOL_GPL(fat_sync_inode);
934 static int fat_show_options(struct seq_file *m, struct dentry *root);
935 static const struct super_operations fat_sops = {
936 .alloc_inode = fat_alloc_inode,
937 .free_inode = fat_free_inode,
938 .write_inode = fat_write_inode,
939 .evict_inode = fat_evict_inode,
940 .put_super = fat_put_super,
941 .statfs = fat_statfs,
942 .remount_fs = fat_remount,
944 .show_options = fat_show_options,
947 static int fat_show_options(struct seq_file *m, struct dentry *root)
949 struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
950 struct fat_mount_options *opts = &sbi->options;
951 int isvfat = opts->isvfat;
953 if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))
954 seq_printf(m, ",uid=%u",
955 from_kuid_munged(&init_user_ns, opts->fs_uid));
956 if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))
957 seq_printf(m, ",gid=%u",
958 from_kgid_munged(&init_user_ns, opts->fs_gid));
959 seq_printf(m, ",fmask=%04o", opts->fs_fmask);
960 seq_printf(m, ",dmask=%04o", opts->fs_dmask);
961 if (opts->allow_utime)
962 seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
964 /* strip "cp" prefix from displayed option */
965 seq_printf(m, ",codepage=%s", &sbi->nls_disk->charset[2]);
968 seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);
970 switch (opts->shortname) {
971 case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
972 seq_puts(m, ",shortname=win95");
974 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
975 seq_puts(m, ",shortname=winnt");
977 case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
978 seq_puts(m, ",shortname=mixed");
980 case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
981 seq_puts(m, ",shortname=lower");
984 seq_puts(m, ",shortname=unknown");
988 if (opts->name_check != 'n')
989 seq_printf(m, ",check=%c", opts->name_check);
991 seq_puts(m, ",usefree");
993 seq_puts(m, ",quiet");
995 seq_puts(m, ",showexec");
996 if (opts->sys_immutable)
997 seq_puts(m, ",sys_immutable");
1000 seq_puts(m, ",dotsOK=yes");
1002 seq_puts(m, ",nocase");
1005 seq_puts(m, ",utf8");
1006 if (opts->unicode_xlate)
1007 seq_puts(m, ",uni_xlate");
1009 seq_puts(m, ",nonumtail");
1011 seq_puts(m, ",rodir");
1014 seq_puts(m, ",flush");
1016 if (opts->time_offset)
1017 seq_printf(m, ",time_offset=%d", opts->time_offset);
1019 seq_puts(m, ",tz=UTC");
1021 if (opts->errors == FAT_ERRORS_CONT)
1022 seq_puts(m, ",errors=continue");
1023 else if (opts->errors == FAT_ERRORS_PANIC)
1024 seq_puts(m, ",errors=panic");
1026 seq_puts(m, ",errors=remount-ro");
1027 if (opts->nfs == FAT_NFS_NOSTALE_RO)
1028 seq_puts(m, ",nfs=nostale_ro");
1030 seq_puts(m, ",nfs=stale_rw");
1032 seq_puts(m, ",discard");
1033 if (opts->dos1xfloppy)
1034 seq_puts(m, ",dos1xfloppy");
1040 Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
1041 Opt_umask, Opt_dmask, Opt_fmask, Opt_allow_utime, Opt_codepage,
1042 Opt_usefree, Opt_nocase, Opt_quiet, Opt_showexec, Opt_debug,
1043 Opt_immutable, Opt_dots, Opt_nodots,
1044 Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
1045 Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
1046 Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
1047 Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
1048 Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_time_offset,
1049 Opt_nfs_stale_rw, Opt_nfs_nostale_ro, Opt_err, Opt_dos1xfloppy,
1052 static const match_table_t fat_tokens = {
1053 {Opt_check_r, "check=relaxed"},
1054 {Opt_check_s, "check=strict"},
1055 {Opt_check_n, "check=normal"},
1056 {Opt_check_r, "check=r"},
1057 {Opt_check_s, "check=s"},
1058 {Opt_check_n, "check=n"},
1059 {Opt_uid, "uid=%u"},
1060 {Opt_gid, "gid=%u"},
1061 {Opt_umask, "umask=%o"},
1062 {Opt_dmask, "dmask=%o"},
1063 {Opt_fmask, "fmask=%o"},
1064 {Opt_allow_utime, "allow_utime=%o"},
1065 {Opt_codepage, "codepage=%u"},
1066 {Opt_usefree, "usefree"},
1067 {Opt_nocase, "nocase"},
1068 {Opt_quiet, "quiet"},
1069 {Opt_showexec, "showexec"},
1070 {Opt_debug, "debug"},
1071 {Opt_immutable, "sys_immutable"},
1072 {Opt_flush, "flush"},
1073 {Opt_tz_utc, "tz=UTC"},
1074 {Opt_time_offset, "time_offset=%d"},
1075 {Opt_err_cont, "errors=continue"},
1076 {Opt_err_panic, "errors=panic"},
1077 {Opt_err_ro, "errors=remount-ro"},
1078 {Opt_discard, "discard"},
1079 {Opt_nfs_stale_rw, "nfs"},
1080 {Opt_nfs_stale_rw, "nfs=stale_rw"},
1081 {Opt_nfs_nostale_ro, "nfs=nostale_ro"},
1082 {Opt_dos1xfloppy, "dos1xfloppy"},
1083 {Opt_obsolete, "conv=binary"},
1084 {Opt_obsolete, "conv=text"},
1085 {Opt_obsolete, "conv=auto"},
1086 {Opt_obsolete, "conv=b"},
1087 {Opt_obsolete, "conv=t"},
1088 {Opt_obsolete, "conv=a"},
1089 {Opt_obsolete, "fat=%u"},
1090 {Opt_obsolete, "blocksize=%u"},
1091 {Opt_obsolete, "cvf_format=%20s"},
1092 {Opt_obsolete, "cvf_options=%100s"},
1093 {Opt_obsolete, "posix"},
1096 static const match_table_t msdos_tokens = {
1097 {Opt_nodots, "nodots"},
1098 {Opt_nodots, "dotsOK=no"},
1100 {Opt_dots, "dotsOK=yes"},
1103 static const match_table_t vfat_tokens = {
1104 {Opt_charset, "iocharset=%s"},
1105 {Opt_shortname_lower, "shortname=lower"},
1106 {Opt_shortname_win95, "shortname=win95"},
1107 {Opt_shortname_winnt, "shortname=winnt"},
1108 {Opt_shortname_mixed, "shortname=mixed"},
1109 {Opt_utf8_no, "utf8=0"}, /* 0 or no or false */
1110 {Opt_utf8_no, "utf8=no"},
1111 {Opt_utf8_no, "utf8=false"},
1112 {Opt_utf8_yes, "utf8=1"}, /* empty or 1 or yes or true */
1113 {Opt_utf8_yes, "utf8=yes"},
1114 {Opt_utf8_yes, "utf8=true"},
1115 {Opt_utf8_yes, "utf8"},
1116 {Opt_uni_xl_no, "uni_xlate=0"}, /* 0 or no or false */
1117 {Opt_uni_xl_no, "uni_xlate=no"},
1118 {Opt_uni_xl_no, "uni_xlate=false"},
1119 {Opt_uni_xl_yes, "uni_xlate=1"}, /* empty or 1 or yes or true */
1120 {Opt_uni_xl_yes, "uni_xlate=yes"},
1121 {Opt_uni_xl_yes, "uni_xlate=true"},
1122 {Opt_uni_xl_yes, "uni_xlate"},
1123 {Opt_nonumtail_no, "nonumtail=0"}, /* 0 or no or false */
1124 {Opt_nonumtail_no, "nonumtail=no"},
1125 {Opt_nonumtail_no, "nonumtail=false"},
1126 {Opt_nonumtail_yes, "nonumtail=1"}, /* empty or 1 or yes or true */
1127 {Opt_nonumtail_yes, "nonumtail=yes"},
1128 {Opt_nonumtail_yes, "nonumtail=true"},
1129 {Opt_nonumtail_yes, "nonumtail"},
1130 {Opt_rodir, "rodir"},
1134 static int parse_options(struct super_block *sb, char *options, int is_vfat,
1135 int silent, int *debug, struct fat_mount_options *opts)
1138 substring_t args[MAX_OPT_ARGS];
1142 opts->isvfat = is_vfat;
1144 opts->fs_uid = current_uid();
1145 opts->fs_gid = current_gid();
1146 opts->fs_fmask = opts->fs_dmask = current_umask();
1147 opts->allow_utime = -1;
1148 opts->codepage = fat_default_codepage;
1149 fat_reset_iocharset(opts);
1151 opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
1154 opts->shortname = 0;
1157 opts->name_check = 'n';
1158 opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK = 0;
1159 opts->unicode_xlate = 0;
1161 opts->usefree = opts->nocase = 0;
1164 opts->errors = FAT_ERRORS_RO;
1167 opts->utf8 = IS_ENABLED(CONFIG_FAT_DEFAULT_UTF8) && is_vfat;
1172 while ((p = strsep(&options, ",")) != NULL) {
1177 token = match_token(p, fat_tokens, args);
1178 if (token == Opt_err) {
1180 token = match_token(p, vfat_tokens, args);
1182 token = match_token(p, msdos_tokens, args);
1186 opts->name_check = 's';
1189 opts->name_check = 'r';
1192 opts->name_check = 'n';
1201 /* for backward compatibility */
1202 opts->shortname = VFAT_SFN_DISPLAY_WIN95
1203 | VFAT_SFN_CREATE_WIN95;
1216 opts->sys_immutable = 1;
1219 if (match_int(&args[0], &option))
1221 opts->fs_uid = make_kuid(current_user_ns(), option);
1222 if (!uid_valid(opts->fs_uid))
1226 if (match_int(&args[0], &option))
1228 opts->fs_gid = make_kgid(current_user_ns(), option);
1229 if (!gid_valid(opts->fs_gid))
1233 if (match_octal(&args[0], &option))
1235 opts->fs_fmask = opts->fs_dmask = option;
1238 if (match_octal(&args[0], &option))
1240 opts->fs_dmask = option;
1243 if (match_octal(&args[0], &option))
1245 opts->fs_fmask = option;
1247 case Opt_allow_utime:
1248 if (match_octal(&args[0], &option))
1250 opts->allow_utime = option & (S_IWGRP | S_IWOTH);
1253 if (match_int(&args[0], &option))
1255 opts->codepage = option;
1260 case Opt_time_offset:
1261 if (match_int(&args[0], &option))
1264 * GMT+-12 zones may have DST corrections so at least
1265 * 13 hours difference is needed. Make the limit 24
1266 * just in case someone invents something unusual.
1268 if (option < -24 * 60 || option > 24 * 60)
1271 opts->time_offset = option;
1275 opts->time_offset = 0;
1278 opts->errors = FAT_ERRORS_CONT;
1281 opts->errors = FAT_ERRORS_PANIC;
1284 opts->errors = FAT_ERRORS_RO;
1286 case Opt_nfs_stale_rw:
1287 opts->nfs = FAT_NFS_STALE_RW;
1289 case Opt_nfs_nostale_ro:
1290 opts->nfs = FAT_NFS_NOSTALE_RO;
1292 case Opt_dos1xfloppy:
1293 opts->dos1xfloppy = 1;
1296 /* msdos specific */
1306 fat_reset_iocharset(opts);
1307 iocharset = match_strdup(&args[0]);
1310 opts->iocharset = iocharset;
1312 case Opt_shortname_lower:
1313 opts->shortname = VFAT_SFN_DISPLAY_LOWER
1314 | VFAT_SFN_CREATE_WIN95;
1316 case Opt_shortname_win95:
1317 opts->shortname = VFAT_SFN_DISPLAY_WIN95
1318 | VFAT_SFN_CREATE_WIN95;
1320 case Opt_shortname_winnt:
1321 opts->shortname = VFAT_SFN_DISPLAY_WINNT
1322 | VFAT_SFN_CREATE_WINNT;
1324 case Opt_shortname_mixed:
1325 opts->shortname = VFAT_SFN_DISPLAY_WINNT
1326 | VFAT_SFN_CREATE_WIN95;
1328 case Opt_utf8_no: /* 0 or no or false */
1331 case Opt_utf8_yes: /* empty or 1 or yes or true */
1334 case Opt_uni_xl_no: /* 0 or no or false */
1335 opts->unicode_xlate = 0;
1337 case Opt_uni_xl_yes: /* empty or 1 or yes or true */
1338 opts->unicode_xlate = 1;
1340 case Opt_nonumtail_no: /* 0 or no or false */
1341 opts->numtail = 1; /* negated option */
1343 case Opt_nonumtail_yes: /* empty or 1 or yes or true */
1344 opts->numtail = 0; /* negated option */
1353 /* obsolete mount options */
1355 fat_msg(sb, KERN_INFO, "\"%s\" option is obsolete, "
1356 "not supported now", p);
1358 /* unknown option */
1361 fat_msg(sb, KERN_ERR,
1362 "Unrecognized mount option \"%s\" "
1363 "or missing value", p);
1370 /* UTF-8 doesn't provide FAT semantics */
1371 if (!strcmp(opts->iocharset, "utf8")) {
1372 fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"
1373 " for FAT filesystems, filesystem will be "
1377 /* If user doesn't specify allow_utime, it's initialized from dmask. */
1378 if (opts->allow_utime == (unsigned short)-1)
1379 opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
1380 if (opts->unicode_xlate)
1382 if (opts->nfs == FAT_NFS_NOSTALE_RO) {
1383 sb->s_flags |= SB_RDONLY;
1384 sb->s_export_op = &fat_export_ops_nostale;
1390 static int fat_read_root(struct inode *inode)
1392 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
1395 MSDOS_I(inode)->i_pos = MSDOS_ROOT_INO;
1396 inode->i_uid = sbi->options.fs_uid;
1397 inode->i_gid = sbi->options.fs_gid;
1398 inode_inc_iversion(inode);
1399 inode->i_generation = 0;
1400 inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
1401 inode->i_op = sbi->dir_ops;
1402 inode->i_fop = &fat_dir_operations;
1403 if (is_fat32(sbi)) {
1404 MSDOS_I(inode)->i_start = sbi->root_cluster;
1405 error = fat_calc_dir_size(inode);
1409 MSDOS_I(inode)->i_start = 0;
1410 inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
1412 inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
1413 & ~((loff_t)sbi->cluster_size - 1)) >> 9;
1414 MSDOS_I(inode)->i_logstart = 0;
1415 MSDOS_I(inode)->mmu_private = inode->i_size;
1417 fat_save_attrs(inode, ATTR_DIR);
1418 inode_set_mtime_to_ts(inode,
1419 inode_set_atime_to_ts(inode, inode_set_ctime(inode, 0, 0)));
1420 set_nlink(inode, fat_subdirs(inode)+2);
1425 static unsigned long calc_fat_clusters(struct super_block *sb)
1427 struct msdos_sb_info *sbi = MSDOS_SB(sb);
1429 /* Divide first to avoid overflow */
1430 if (!is_fat12(sbi)) {
1431 unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
1432 return ent_per_sec * sbi->fat_length;
1435 return sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
1438 static bool fat_bpb_is_zero(struct fat_boot_sector *b)
1440 if (get_unaligned_le16(&b->sector_size))
1442 if (b->sec_per_clus)
1448 if (get_unaligned_le16(&b->dir_entries))
1450 if (get_unaligned_le16(&b->sectors))
1463 static int fat_read_bpb(struct super_block *sb, struct fat_boot_sector *b,
1464 int silent, struct fat_bios_param_block *bpb)
1466 int error = -EINVAL;
1468 /* Read in BPB ... */
1469 memset(bpb, 0, sizeof(*bpb));
1470 bpb->fat_sector_size = get_unaligned_le16(&b->sector_size);
1471 bpb->fat_sec_per_clus = b->sec_per_clus;
1472 bpb->fat_reserved = le16_to_cpu(b->reserved);
1473 bpb->fat_fats = b->fats;
1474 bpb->fat_dir_entries = get_unaligned_le16(&b->dir_entries);
1475 bpb->fat_sectors = get_unaligned_le16(&b->sectors);
1476 bpb->fat_fat_length = le16_to_cpu(b->fat_length);
1477 bpb->fat_total_sect = le32_to_cpu(b->total_sect);
1479 bpb->fat16_state = b->fat16.state;
1480 bpb->fat16_vol_id = get_unaligned_le32(b->fat16.vol_id);
1482 bpb->fat32_length = le32_to_cpu(b->fat32.length);
1483 bpb->fat32_root_cluster = le32_to_cpu(b->fat32.root_cluster);
1484 bpb->fat32_info_sector = le16_to_cpu(b->fat32.info_sector);
1485 bpb->fat32_state = b->fat32.state;
1486 bpb->fat32_vol_id = get_unaligned_le32(b->fat32.vol_id);
1488 /* Validate this looks like a FAT filesystem BPB */
1489 if (!bpb->fat_reserved) {
1491 fat_msg(sb, KERN_ERR,
1492 "bogus number of reserved sectors");
1495 if (!bpb->fat_fats) {
1497 fat_msg(sb, KERN_ERR, "bogus number of FAT structure");
1502 * Earlier we checked here that b->secs_track and b->head are nonzero,
1503 * but it turns out valid FAT filesystems can have zero there.
1506 if (!fat_valid_media(b->media)) {
1508 fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
1509 (unsigned)b->media);
1513 if (!is_power_of_2(bpb->fat_sector_size)
1514 || (bpb->fat_sector_size < 512)
1515 || (bpb->fat_sector_size > 4096)) {
1517 fat_msg(sb, KERN_ERR, "bogus logical sector size %u",
1518 (unsigned)bpb->fat_sector_size);
1522 if (!is_power_of_2(bpb->fat_sec_per_clus)) {
1524 fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
1525 (unsigned)bpb->fat_sec_per_clus);
1529 if (bpb->fat_fat_length == 0 && bpb->fat32_length == 0) {
1531 fat_msg(sb, KERN_ERR, "bogus number of FAT sectors");
1541 static int fat_read_static_bpb(struct super_block *sb,
1542 struct fat_boot_sector *b, int silent,
1543 struct fat_bios_param_block *bpb)
1545 static const char *notdos1x = "This doesn't look like a DOS 1.x volume";
1546 sector_t bd_sects = bdev_nr_sectors(sb->s_bdev);
1547 struct fat_floppy_defaults *fdefaults = NULL;
1548 int error = -EINVAL;
1551 /* 16-bit DOS 1.x reliably wrote bootstrap short-jmp code */
1552 if (b->ignored[0] != 0xeb || b->ignored[2] != 0x90) {
1554 fat_msg(sb, KERN_ERR,
1555 "%s; no bootstrapping code", notdos1x);
1560 * If any value in this region is non-zero, it isn't archaic
1563 if (!fat_bpb_is_zero(b)) {
1565 fat_msg(sb, KERN_ERR,
1566 "%s; DOS 2.x BPB is non-zero", notdos1x);
1570 for (i = 0; i < ARRAY_SIZE(floppy_defaults); i++) {
1571 if (floppy_defaults[i].nr_sectors == bd_sects) {
1572 fdefaults = &floppy_defaults[i];
1577 if (fdefaults == NULL) {
1579 fat_msg(sb, KERN_WARNING,
1580 "This looks like a DOS 1.x volume, but isn't a recognized floppy size (%llu sectors)",
1586 fat_msg(sb, KERN_INFO,
1587 "This looks like a DOS 1.x volume; assuming default BPB values");
1589 memset(bpb, 0, sizeof(*bpb));
1590 bpb->fat_sector_size = SECTOR_SIZE;
1591 bpb->fat_sec_per_clus = fdefaults->sec_per_clus;
1592 bpb->fat_reserved = 1;
1594 bpb->fat_dir_entries = fdefaults->dir_entries;
1595 bpb->fat_sectors = fdefaults->nr_sectors;
1596 bpb->fat_fat_length = fdefaults->fat_length;
1605 * Read the super block of an MS-DOS FS.
1607 int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
1608 void (*setup)(struct super_block *))
1610 struct inode *root_inode = NULL, *fat_inode = NULL;
1611 struct inode *fsinfo_inode = NULL;
1612 struct buffer_head *bh;
1613 struct fat_bios_param_block bpb;
1614 struct msdos_sb_info *sbi;
1615 u16 logical_sector_size;
1616 u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
1620 struct timespec64 ts;
1623 * GFP_KERNEL is ok here, because while we do hold the
1624 * superblock lock, memory pressure can't call back into
1625 * the filesystem, since we're only just about to mount
1626 * it and have no inodes etc active!
1628 sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
1631 sb->s_fs_info = sbi;
1633 sb->s_flags |= SB_NODIRATIME;
1634 sb->s_magic = MSDOS_SUPER_MAGIC;
1635 sb->s_op = &fat_sops;
1636 sb->s_export_op = &fat_export_ops;
1638 * fat timestamps are complex and truncated by fat itself, so
1639 * we set 1 here to be fast
1641 sb->s_time_gran = 1;
1642 mutex_init(&sbi->nfs_build_inode_lock);
1643 ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
1644 DEFAULT_RATELIMIT_BURST);
1646 error = parse_options(sb, data, isvfat, silent, &debug, &sbi->options);
1650 setup(sb); /* flavour-specific stuff that needs options */
1653 sb_min_blocksize(sb, 512);
1654 bh = sb_bread(sb, 0);
1656 fat_msg(sb, KERN_ERR, "unable to read boot sector");
1660 error = fat_read_bpb(sb, (struct fat_boot_sector *)bh->b_data, silent,
1662 if (error == -EINVAL && sbi->options.dos1xfloppy)
1663 error = fat_read_static_bpb(sb,
1664 (struct fat_boot_sector *)bh->b_data, silent, &bpb);
1667 if (error == -EINVAL)
1672 logical_sector_size = bpb.fat_sector_size;
1673 sbi->sec_per_clus = bpb.fat_sec_per_clus;
1676 if (logical_sector_size < sb->s_blocksize) {
1677 fat_msg(sb, KERN_ERR, "logical sector size too small for device"
1678 " (logical sector size = %u)", logical_sector_size);
1682 if (logical_sector_size > sb->s_blocksize) {
1683 struct buffer_head *bh_resize;
1685 if (!sb_set_blocksize(sb, logical_sector_size)) {
1686 fat_msg(sb, KERN_ERR, "unable to set blocksize %u",
1687 logical_sector_size);
1691 /* Verify that the larger boot sector is fully readable */
1692 bh_resize = sb_bread(sb, 0);
1693 if (bh_resize == NULL) {
1694 fat_msg(sb, KERN_ERR, "unable to read boot sector"
1695 " (logical sector size = %lu)",
1702 mutex_init(&sbi->s_lock);
1703 sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
1704 sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
1705 sbi->fats = bpb.fat_fats;
1706 sbi->fat_bits = 0; /* Don't know yet */
1707 sbi->fat_start = bpb.fat_reserved;
1708 sbi->fat_length = bpb.fat_fat_length;
1709 sbi->root_cluster = 0;
1710 sbi->free_clusters = -1; /* Don't know yet */
1711 sbi->free_clus_valid = 0;
1712 sbi->prev_free = FAT_START_ENT;
1713 sb->s_maxbytes = 0xffffffff;
1714 fat_time_fat2unix(sbi, &ts, 0, cpu_to_le16(FAT_DATE_MIN), 0);
1715 sb->s_time_min = ts.tv_sec;
1717 fat_time_fat2unix(sbi, &ts, cpu_to_le16(FAT_TIME_MAX),
1718 cpu_to_le16(FAT_DATE_MAX), 0);
1719 sb->s_time_max = ts.tv_sec;
1721 if (!sbi->fat_length && bpb.fat32_length) {
1722 struct fat_boot_fsinfo *fsinfo;
1723 struct buffer_head *fsinfo_bh;
1727 sbi->fat_length = bpb.fat32_length;
1728 sbi->root_cluster = bpb.fat32_root_cluster;
1730 /* MC - if info_sector is 0, don't multiply by 0 */
1731 sbi->fsinfo_sector = bpb.fat32_info_sector;
1732 if (sbi->fsinfo_sector == 0)
1733 sbi->fsinfo_sector = 1;
1735 fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
1736 if (fsinfo_bh == NULL) {
1737 fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"
1738 " (sector = %lu)", sbi->fsinfo_sector);
1742 fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
1743 if (!IS_FSINFO(fsinfo)) {
1744 fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
1745 "0x%08x, 0x%08x (sector = %lu)",
1746 le32_to_cpu(fsinfo->signature1),
1747 le32_to_cpu(fsinfo->signature2),
1748 sbi->fsinfo_sector);
1750 if (sbi->options.usefree)
1751 sbi->free_clus_valid = 1;
1752 sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
1753 sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
1759 /* interpret volume ID as a little endian 32 bit integer */
1761 sbi->vol_id = bpb.fat32_vol_id;
1762 else /* fat 16 or 12 */
1763 sbi->vol_id = bpb.fat16_vol_id;
1765 sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
1766 sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
1768 sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
1769 sbi->dir_entries = bpb.fat_dir_entries;
1770 if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
1772 fat_msg(sb, KERN_ERR, "bogus number of directory entries"
1773 " (%u)", sbi->dir_entries);
1777 rootdir_sectors = sbi->dir_entries
1778 * sizeof(struct msdos_dir_entry) / sb->s_blocksize;
1779 sbi->data_start = sbi->dir_start + rootdir_sectors;
1780 total_sectors = bpb.fat_sectors;
1781 if (total_sectors == 0)
1782 total_sectors = bpb.fat_total_sect;
1784 total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
1787 sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
1789 /* some OSes set FAT_STATE_DIRTY and clean it on unmount. */
1791 sbi->dirty = bpb.fat32_state & FAT_STATE_DIRTY;
1792 else /* fat 16 or 12 */
1793 sbi->dirty = bpb.fat16_state & FAT_STATE_DIRTY;
1795 /* check that FAT table does not overflow */
1796 fat_clusters = calc_fat_clusters(sb);
1797 total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
1798 if (total_clusters > max_fat(sb)) {
1800 fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
1805 sbi->max_cluster = total_clusters + FAT_START_ENT;
1806 /* check the free_clusters, it's not necessarily correct */
1807 if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
1808 sbi->free_clusters = -1;
1809 /* check the prev_free, it's not necessarily correct */
1810 sbi->prev_free %= sbi->max_cluster;
1811 if (sbi->prev_free < FAT_START_ENT)
1812 sbi->prev_free = FAT_START_ENT;
1814 /* set up enough so that it can read an inode */
1817 fat_ent_access_init(sb);
1820 * The low byte of the first FAT entry must have the same value as
1821 * the media field of the boot sector. But in real world, too many
1822 * devices are writing wrong values. So, removed that validity check.
1824 * The removed check compared the first FAT entry to a value dependent
1825 * on the media field like this:
1826 * == (0x0F00 | media), for FAT12
1827 * == (0XFF00 | media), for FAT16
1828 * == (0x0FFFFF | media), for FAT32
1832 sprintf(buf, "cp%d", sbi->options.codepage);
1833 sbi->nls_disk = load_nls(buf);
1834 if (!sbi->nls_disk) {
1835 fat_msg(sb, KERN_ERR, "codepage %s not found", buf);
1839 /* FIXME: utf8 is using iocharset for upper/lower conversion */
1840 if (sbi->options.isvfat) {
1841 sbi->nls_io = load_nls(sbi->options.iocharset);
1843 fat_msg(sb, KERN_ERR, "IO charset %s not found",
1844 sbi->options.iocharset);
1850 fat_inode = new_inode(sb);
1853 sbi->fat_inode = fat_inode;
1855 fsinfo_inode = new_inode(sb);
1858 fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
1859 sbi->fsinfo_inode = fsinfo_inode;
1860 insert_inode_hash(fsinfo_inode);
1862 root_inode = new_inode(sb);
1865 root_inode->i_ino = MSDOS_ROOT_INO;
1866 inode_set_iversion(root_inode, 1);
1867 error = fat_read_root(root_inode);
1873 insert_inode_hash(root_inode);
1874 fat_attach(root_inode, 0);
1875 sb->s_root = d_make_root(root_inode);
1877 fat_msg(sb, KERN_ERR, "get root inode failed");
1881 if (sbi->options.discard && !bdev_max_discard_sectors(sb->s_bdev))
1882 fat_msg(sb, KERN_WARNING,
1883 "mounting with \"discard\" option, but the device does not support discard");
1885 fat_set_state(sb, 1, 0);
1891 fat_msg(sb, KERN_INFO, "Can't find a valid FAT filesystem");
1896 unload_nls(sbi->nls_io);
1897 unload_nls(sbi->nls_disk);
1898 fat_reset_iocharset(&sbi->options);
1899 sb->s_fs_info = NULL;
1904 EXPORT_SYMBOL_GPL(fat_fill_super);
1907 * helper function for fat_flush_inodes. This writes both the inode
1908 * and the file data blocks, waiting for in flight data blocks before
1909 * the start of the call. It does not wait for any io started
1912 static int writeback_inode(struct inode *inode)
1917 /* if we used wait=1, sync_inode_metadata waits for the io for the
1918 * inode to finish. So wait=0 is sent down to sync_inode_metadata
1919 * and filemap_fdatawrite is used for the data blocks
1921 ret = sync_inode_metadata(inode, 0);
1923 ret = filemap_fdatawrite(inode->i_mapping);
1928 * write data and metadata corresponding to i1 and i2. The io is
1929 * started but we do not wait for any of it to finish.
1931 * filemap_flush is used for the block device, so if there is a dirty
1932 * page for a block already in flight, we will not wait and start the
1935 int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
1938 if (!MSDOS_SB(sb)->options.flush)
1941 ret = writeback_inode(i1);
1943 ret = writeback_inode(i2);
1945 ret = sync_blockdev_nowait(sb->s_bdev);
1948 EXPORT_SYMBOL_GPL(fat_flush_inodes);
1950 static int __init init_fat_fs(void)
1954 err = fat_cache_init();
1958 err = fat_init_inodecache();
1965 fat_cache_destroy();
1969 static void __exit exit_fat_fs(void)
1971 fat_cache_destroy();
1972 fat_destroy_inodecache();
1975 module_init(init_fat_fs)
1976 module_exit(exit_fat_fs)
1978 MODULE_LICENSE("GPL");