[PATCH] fat: support ->direct_IO()
This patch add to support of ->direct_IO() for mostly read. The user of this seems to want to use for streaming read. So, current direct I/O has limitation, it can only overwrite. (For write operation, mainly we need to handle the hole etc..) Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
OGAWA Hirofumi
Linus Torvalds
parent
7c709d00d6
commit
e5174baaea
@ -295,7 +295,8 @@ static int fat_bmap_cluster(struct inode *inode, int cluster)
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return dclus;
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}
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int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys)
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int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
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unsigned long *mapped_blocks)
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{
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struct super_block *sb = inode->i_sb;
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struct msdos_sb_info *sbi = MSDOS_SB(sb);
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@ -303,9 +304,12 @@ int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys)
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int cluster, offset;
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*phys = 0;
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*mapped_blocks = 0;
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if ((sbi->fat_bits != 32) && (inode->i_ino == MSDOS_ROOT_INO)) {
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if (sector < (sbi->dir_entries >> sbi->dir_per_block_bits))
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if (sector < (sbi->dir_entries >> sbi->dir_per_block_bits)) {
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*phys = sector + sbi->dir_start;
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*mapped_blocks = 1;
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}
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return 0;
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}
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last_block = (MSDOS_I(inode)->mmu_private + (sb->s_blocksize - 1))
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@ -318,7 +322,11 @@ int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys)
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cluster = fat_bmap_cluster(inode, cluster);
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if (cluster < 0)
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return cluster;
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else if (cluster)
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else if (cluster) {
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*phys = fat_clus_to_blknr(sbi, cluster) + offset;
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*mapped_blocks = sbi->sec_per_clus - offset;
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if (*mapped_blocks > last_block - sector)
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*mapped_blocks = last_block - sector;
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}
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return 0;
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}
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@ -68,8 +68,8 @@ static int fat__get_entry(struct inode *dir, loff_t *pos,
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{
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struct super_block *sb = dir->i_sb;
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sector_t phys, iblock;
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int offset;
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int err;
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unsigned long mapped_blocks;
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int err, offset;
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next:
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if (*bh)
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@ -77,7 +77,7 @@ next:
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*bh = NULL;
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iblock = *pos >> sb->s_blocksize_bits;
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err = fat_bmap(dir, iblock, &phys);
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err = fat_bmap(dir, iblock, &phys, &mapped_blocks);
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if (err || !phys)
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return -1; /* beyond EOF or error */
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@ -23,6 +23,7 @@
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#include <linux/mount.h>
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#include <linux/vfs.h>
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#include <linux/parser.h>
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#include <linux/uio.h>
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#include <asm/unaligned.h>
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#ifndef CONFIG_FAT_DEFAULT_IOCHARSET
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@ -49,43 +50,77 @@ static int fat_add_cluster(struct inode *inode)
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return err;
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}
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static int fat_get_block(struct inode *inode, sector_t iblock,
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struct buffer_head *bh_result, int create)
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static int __fat_get_blocks(struct inode *inode, sector_t iblock,
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unsigned long *max_blocks,
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struct buffer_head *bh_result, int create)
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{
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struct super_block *sb = inode->i_sb;
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struct msdos_sb_info *sbi = MSDOS_SB(sb);
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sector_t phys;
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int err;
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unsigned long mapped_blocks;
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int err, offset;
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err = fat_bmap(inode, iblock, &phys);
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err = fat_bmap(inode, iblock, &phys, &mapped_blocks);
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if (err)
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return err;
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if (phys) {
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map_bh(bh_result, sb, phys);
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*max_blocks = min(mapped_blocks, *max_blocks);
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return 0;
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}
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if (!create)
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return 0;
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if (iblock != MSDOS_I(inode)->mmu_private >> sb->s_blocksize_bits) {
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fat_fs_panic(sb, "corrupted file size (i_pos %lld, %lld)",
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MSDOS_I(inode)->i_pos, MSDOS_I(inode)->mmu_private);
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return -EIO;
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}
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if (!((unsigned long)iblock & (MSDOS_SB(sb)->sec_per_clus - 1))) {
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offset = (unsigned long)iblock & (sbi->sec_per_clus - 1);
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if (!offset) {
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/* TODO: multiple cluster allocation would be desirable. */
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err = fat_add_cluster(inode);
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if (err)
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return err;
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}
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MSDOS_I(inode)->mmu_private += sb->s_blocksize;
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err = fat_bmap(inode, iblock, &phys);
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/* available blocks on this cluster */
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mapped_blocks = sbi->sec_per_clus - offset;
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*max_blocks = min(mapped_blocks, *max_blocks);
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MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;
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err = fat_bmap(inode, iblock, &phys, &mapped_blocks);
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if (err)
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return err;
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if (!phys)
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BUG();
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BUG_ON(!phys);
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BUG_ON(*max_blocks != mapped_blocks);
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set_buffer_new(bh_result);
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map_bh(bh_result, sb, phys);
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return 0;
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}
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static int fat_get_blocks(struct inode *inode, sector_t iblock,
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unsigned long max_blocks,
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struct buffer_head *bh_result, int create)
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{
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struct super_block *sb = inode->i_sb;
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int err;
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err = __fat_get_blocks(inode, iblock, &max_blocks, bh_result, create);
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if (err)
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return err;
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bh_result->b_size = max_blocks << sb->s_blocksize_bits;
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return 0;
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}
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static int fat_get_block(struct inode *inode, sector_t iblock,
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struct buffer_head *bh_result, int create)
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{
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unsigned long max_blocks = 1;
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return __fat_get_blocks(inode, iblock, &max_blocks, bh_result, create);
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}
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static int fat_writepage(struct page *page, struct writeback_control *wbc)
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{
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return block_write_full_page(page, fat_get_block, wbc);
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@ -128,6 +163,34 @@ static int fat_commit_write(struct file *file, struct page *page,
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return err;
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}
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static ssize_t fat_direct_IO(int rw, struct kiocb *iocb,
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const struct iovec *iov,
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loff_t offset, unsigned long nr_segs)
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{
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struct file *file = iocb->ki_filp;
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struct inode *inode = file->f_mapping->host;
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if (rw == WRITE) {
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/*
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* FIXME: blockdev_direct_IO() doesn't use ->prepare_write(),
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* so we need to update the ->mmu_private to block boundary.
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*
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* But we must fill the remaining area or hole by nul for
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* updating ->mmu_private.
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*/
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loff_t size = offset + iov_length(iov, nr_segs);
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if (MSDOS_I(inode)->mmu_private < size)
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return -EINVAL;
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}
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/*
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* FAT need to use the DIO_LOCKING for avoiding the race
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* condition of fat_get_block() and ->truncate().
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*/
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return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
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offset, nr_segs, fat_get_blocks, NULL);
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}
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static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
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{
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return generic_block_bmap(mapping, block, fat_get_block);
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@ -141,6 +204,7 @@ static struct address_space_operations fat_aops = {
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.sync_page = block_sync_page,
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.prepare_write = fat_prepare_write,
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.commit_write = fat_commit_write,
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.direct_IO = fat_direct_IO,
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.bmap = _fat_bmap
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};
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@ -329,7 +329,8 @@ static inline void fatwchar_to16(__u8 *dst, const wchar_t *src, size_t len)
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extern void fat_cache_inval_inode(struct inode *inode);
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extern int fat_get_cluster(struct inode *inode, int cluster,
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int *fclus, int *dclus);
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extern int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys);
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extern int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
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unsigned long *mapped_blocks);
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/* fat/dir.c */
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extern struct file_operations fat_dir_operations;
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