Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1252 insertions, 0 deletions

diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c
new file mode 100644
index 0000000000..e1586bba6d
--- /dev/null
+++ b/fs/exfat/dir.c
@@ -0,0 +1,1252 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
+ */
+
+#include <linux/slab.h>
+#include <linux/compat.h>
+#include <linux/bio.h>
+#include <linux/buffer_head.h>
+
+#include "exfat_raw.h"
+#include "exfat_fs.h"
+
+static int exfat_extract_uni_name(struct exfat_dentry *ep,
+		unsigned short *uniname)
+{
+	int i, len = 0;
+
+	for (i = 0; i < EXFAT_FILE_NAME_LEN; i++) {
+		*uniname = le16_to_cpu(ep->dentry.name.unicode_0_14[i]);
+		if (*uniname == 0x0)
+			return len;
+		uniname++;
+		len++;
+	}
+
+	*uniname = 0x0;
+	return len;
+
+}
+
+static int exfat_get_uniname_from_ext_entry(struct super_block *sb,
+		struct exfat_chain *p_dir, int entry, unsigned short *uniname)
+{
+	int i, err;
+	struct exfat_entry_set_cache es;
+	unsigned int uni_len = 0, len;
+
+	err = exfat_get_dentry_set(&es, sb, p_dir, entry, ES_ALL_ENTRIES);
+	if (err)
+		return err;
+
+	/*
+	 * First entry  : file entry
+	 * Second entry : stream-extension entry
+	 * Third entry  : first file-name entry
+	 * So, the index of first file-name dentry should start from 2.
+	 */
+	for (i = ES_IDX_FIRST_FILENAME; i < es.num_entries; i++) {
+		struct exfat_dentry *ep = exfat_get_dentry_cached(&es, i);
+
+		/* end of name entry */
+		if (exfat_get_entry_type(ep) != TYPE_EXTEND)
+			break;
+
+		len = exfat_extract_uni_name(ep, uniname);
+		uni_len += len;
+		if (len != EXFAT_FILE_NAME_LEN || uni_len >= MAX_NAME_LENGTH)
+			break;
+		uniname += EXFAT_FILE_NAME_LEN;
+	}
+
+	exfat_put_dentry_set(&es, false);
+	return 0;
+}
+
+/* read a directory entry from the opened directory */
+static int exfat_readdir(struct inode *inode, loff_t *cpos, struct exfat_dir_entry *dir_entry)
+{
+	int i, dentries_per_clu, num_ext, err;
+	unsigned int type, clu_offset, max_dentries;
+	struct exfat_chain dir, clu;
+	struct exfat_uni_name uni_name;
+	struct exfat_dentry *ep;
+	struct super_block *sb = inode->i_sb;
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+	struct exfat_inode_info *ei = EXFAT_I(inode);
+	unsigned int dentry = EXFAT_B_TO_DEN(*cpos) & 0xFFFFFFFF;
+	struct buffer_head *bh;
+
+	/* check if the given file ID is opened */
+	if (ei->type != TYPE_DIR)
+		return -EPERM;
+
+	if (ei->entry == -1)
+		exfat_chain_set(&dir, sbi->root_dir, 0, ALLOC_FAT_CHAIN);
+	else
+		exfat_chain_set(&dir, ei->start_clu,
+			EXFAT_B_TO_CLU(i_size_read(inode), sbi), ei->flags);
+
+	dentries_per_clu = sbi->dentries_per_clu;
+	max_dentries = (unsigned int)min_t(u64, MAX_EXFAT_DENTRIES,
+				(u64)EXFAT_CLU_TO_DEN(sbi->num_clusters, sbi));
+
+	clu_offset = EXFAT_DEN_TO_CLU(dentry, sbi);
+	exfat_chain_dup(&clu, &dir);
+
+	if (clu.flags == ALLOC_NO_FAT_CHAIN) {
+		clu.dir += clu_offset;
+		clu.size -= clu_offset;
+	} else {
+		/* hint_information */
+		if (clu_offset > 0 && ei->hint_bmap.off != EXFAT_EOF_CLUSTER &&
+		    ei->hint_bmap.off > 0 && clu_offset >= ei->hint_bmap.off) {
+			clu_offset -= ei->hint_bmap.off;
+			clu.dir = ei->hint_bmap.clu;
+		}
+
+		while (clu_offset > 0 && clu.dir != EXFAT_EOF_CLUSTER) {
+			if (exfat_get_next_cluster(sb, &(clu.dir)))
+				return -EIO;
+
+			clu_offset--;
+		}
+	}
+
+	while (clu.dir != EXFAT_EOF_CLUSTER && dentry < max_dentries) {
+		i = dentry & (dentries_per_clu - 1);
+
+		for ( ; i < dentries_per_clu; i++, dentry++) {
+			ep = exfat_get_dentry(sb, &clu, i, &bh);
+			if (!ep)
+				return -EIO;
+
+			type = exfat_get_entry_type(ep);
+			if (type == TYPE_UNUSED) {
+				brelse(bh);
+				break;
+			}
+
+			if (type != TYPE_FILE && type != TYPE_DIR) {
+				brelse(bh);
+				continue;
+			}
+
+			num_ext = ep->dentry.file.num_ext;
+			dir_entry->attr = le16_to_cpu(ep->dentry.file.attr);
+			exfat_get_entry_time(sbi, &dir_entry->crtime,
+					ep->dentry.file.create_tz,
+					ep->dentry.file.create_time,
+					ep->dentry.file.create_date,
+					ep->dentry.file.create_time_cs);
+			exfat_get_entry_time(sbi, &dir_entry->mtime,
+					ep->dentry.file.modify_tz,
+					ep->dentry.file.modify_time,
+					ep->dentry.file.modify_date,
+					ep->dentry.file.modify_time_cs);
+			exfat_get_entry_time(sbi, &dir_entry->atime,
+					ep->dentry.file.access_tz,
+					ep->dentry.file.access_time,
+					ep->dentry.file.access_date,
+					0);
+
+			*uni_name.name = 0x0;
+			err = exfat_get_uniname_from_ext_entry(sb, &clu, i,
+				uni_name.name);
+			if (err) {
+				brelse(bh);
+				continue;
+			}
+			exfat_utf16_to_nls(sb, &uni_name,
+				dir_entry->namebuf.lfn,
+				dir_entry->namebuf.lfnbuf_len);
+			brelse(bh);
+
+			ep = exfat_get_dentry(sb, &clu, i + 1, &bh);
+			if (!ep)
+				return -EIO;
+			dir_entry->size =
+				le64_to_cpu(ep->dentry.stream.valid_size);
+			dir_entry->entry = dentry;
+			brelse(bh);
+
+			ei->hint_bmap.off = EXFAT_DEN_TO_CLU(dentry, sbi);
+			ei->hint_bmap.clu = clu.dir;
+
+			*cpos = EXFAT_DEN_TO_B(dentry + 1 + num_ext);
+			return 0;
+		}
+
+		if (clu.flags == ALLOC_NO_FAT_CHAIN) {
+			if (--clu.size > 0)
+				clu.dir++;
+			else
+				clu.dir = EXFAT_EOF_CLUSTER;
+		} else {
+			if (exfat_get_next_cluster(sb, &(clu.dir)))
+				return -EIO;
+		}
+	}
+
+	dir_entry->namebuf.lfn[0] = '\0';
+	*cpos = EXFAT_DEN_TO_B(dentry);
+	return 0;
+}
+
+static void exfat_init_namebuf(struct exfat_dentry_namebuf *nb)
+{
+	nb->lfn = NULL;
+	nb->lfnbuf_len = 0;
+}
+
+static int exfat_alloc_namebuf(struct exfat_dentry_namebuf *nb)
+{
+	nb->lfn = __getname();
+	if (!nb->lfn)
+		return -ENOMEM;
+	nb->lfnbuf_len = MAX_VFSNAME_BUF_SIZE;
+	return 0;
+}
+
+static void exfat_free_namebuf(struct exfat_dentry_namebuf *nb)
+{
+	if (!nb->lfn)
+		return;
+
+	__putname(nb->lfn);
+	exfat_init_namebuf(nb);
+}
+
+/*
+ * Before calling dir_emit*(), sbi->s_lock should be released
+ * because page fault can occur in dir_emit*().
+ */
+#define ITER_POS_FILLED_DOTS    (2)
+static int exfat_iterate(struct file *file, struct dir_context *ctx)
+{
+	struct inode *inode = file_inode(file);
+	struct super_block *sb = inode->i_sb;
+	struct inode *tmp;
+	struct exfat_dir_entry de;
+	struct exfat_dentry_namebuf *nb = &(de.namebuf);
+	struct exfat_inode_info *ei = EXFAT_I(inode);
+	unsigned long inum;
+	loff_t cpos, i_pos;
+	int err = 0, fake_offset = 0;
+
+	exfat_init_namebuf(nb);
+
+	cpos = ctx->pos;
+	if (!dir_emit_dots(file, ctx))
+		goto out;
+
+	if (ctx->pos == ITER_POS_FILLED_DOTS) {
+		cpos = 0;
+		fake_offset = 1;
+	}
+
+	cpos = round_up(cpos, DENTRY_SIZE);
+
+	/* name buffer should be allocated before use */
+	err = exfat_alloc_namebuf(nb);
+	if (err)
+		goto out;
+get_new:
+	mutex_lock(&EXFAT_SB(sb)->s_lock);
+
+	if (ei->flags == ALLOC_NO_FAT_CHAIN && cpos >= i_size_read(inode))
+		goto end_of_dir;
+
+	err = exfat_readdir(inode, &cpos, &de);
+	if (err) {
+		/*
+		 * At least we tried to read a sector.
+		 * Move cpos to next sector position (should be aligned).
+		 */
+		if (err == -EIO) {
+			cpos += 1 << (sb->s_blocksize_bits);
+			cpos &= ~(sb->s_blocksize - 1);
+		}
+
+		err = -EIO;
+		goto end_of_dir;
+	}
+
+	if (!nb->lfn[0])
+		goto end_of_dir;
+
+	i_pos = ((loff_t)ei->start_clu << 32) |	(de.entry & 0xffffffff);
+	tmp = exfat_iget(sb, i_pos);
+	if (tmp) {
+		inum = tmp->i_ino;
+		iput(tmp);
+	} else {
+		inum = iunique(sb, EXFAT_ROOT_INO);
+	}
+
+	mutex_unlock(&EXFAT_SB(sb)->s_lock);
+	if (!dir_emit(ctx, nb->lfn, strlen(nb->lfn), inum,
+			(de.attr & ATTR_SUBDIR) ? DT_DIR : DT_REG))
+		goto out;
+	ctx->pos = cpos;
+	goto get_new;
+
+end_of_dir:
+	if (!cpos && fake_offset)
+		cpos = ITER_POS_FILLED_DOTS;
+	ctx->pos = cpos;
+	mutex_unlock(&EXFAT_SB(sb)->s_lock);
+out:
+	/*
+	 * To improve performance, free namebuf after unlock sb_lock.
+	 * If namebuf is not allocated, this function do nothing
+	 */
+	exfat_free_namebuf(nb);
+	return err;
+}
+
+WRAP_DIR_ITER(exfat_iterate) // FIXME!
+const struct file_operations exfat_dir_operations = {
+	.llseek		= generic_file_llseek,
+	.read		= generic_read_dir,
+	.iterate_shared	= shared_exfat_iterate,
+	.unlocked_ioctl = exfat_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl = exfat_compat_ioctl,
+#endif
+	.fsync		= exfat_file_fsync,
+};
+
+int exfat_alloc_new_dir(struct inode *inode, struct exfat_chain *clu)
+{
+	int ret;
+
+	exfat_chain_set(clu, EXFAT_EOF_CLUSTER, 0, ALLOC_NO_FAT_CHAIN);
+
+	ret = exfat_alloc_cluster(inode, 1, clu, IS_DIRSYNC(inode));
+	if (ret)
+		return ret;
+
+	return exfat_zeroed_cluster(inode, clu->dir);
+}
+
+int exfat_calc_num_entries(struct exfat_uni_name *p_uniname)
+{
+	int len;
+
+	len = p_uniname->name_len;
+	if (len == 0)
+		return -EINVAL;
+
+	/* 1 file entry + 1 stream entry + name entries */
+	return ES_ENTRY_NUM(len);
+}
+
+unsigned int exfat_get_entry_type(struct exfat_dentry *ep)
+{
+	if (ep->type == EXFAT_UNUSED)
+		return TYPE_UNUSED;
+	if (IS_EXFAT_DELETED(ep->type))
+		return TYPE_DELETED;
+	if (ep->type == EXFAT_INVAL)
+		return TYPE_INVALID;
+	if (IS_EXFAT_CRITICAL_PRI(ep->type)) {
+		if (ep->type == EXFAT_BITMAP)
+			return TYPE_BITMAP;
+		if (ep->type == EXFAT_UPCASE)
+			return TYPE_UPCASE;
+		if (ep->type == EXFAT_VOLUME)
+			return TYPE_VOLUME;
+		if (ep->type == EXFAT_FILE) {
+			if (le16_to_cpu(ep->dentry.file.attr) & ATTR_SUBDIR)
+				return TYPE_DIR;
+			return TYPE_FILE;
+		}
+		return TYPE_CRITICAL_PRI;
+	}
+	if (IS_EXFAT_BENIGN_PRI(ep->type)) {
+		if (ep->type == EXFAT_GUID)
+			return TYPE_GUID;
+		if (ep->type == EXFAT_PADDING)
+			return TYPE_PADDING;
+		if (ep->type == EXFAT_ACLTAB)
+			return TYPE_ACLTAB;
+		return TYPE_BENIGN_PRI;
+	}
+	if (IS_EXFAT_CRITICAL_SEC(ep->type)) {
+		if (ep->type == EXFAT_STREAM)
+			return TYPE_STREAM;
+		if (ep->type == EXFAT_NAME)
+			return TYPE_EXTEND;
+		if (ep->type == EXFAT_ACL)
+			return TYPE_ACL;
+		return TYPE_CRITICAL_SEC;
+	}
+
+	if (ep->type == EXFAT_VENDOR_EXT)
+		return TYPE_VENDOR_EXT;
+	if (ep->type == EXFAT_VENDOR_ALLOC)
+		return TYPE_VENDOR_ALLOC;
+
+	return TYPE_BENIGN_SEC;
+}
+
+static void exfat_set_entry_type(struct exfat_dentry *ep, unsigned int type)
+{
+	if (type == TYPE_UNUSED) {
+		ep->type = EXFAT_UNUSED;
+	} else if (type == TYPE_DELETED) {
+		ep->type &= EXFAT_DELETE;
+	} else if (type == TYPE_STREAM) {
+		ep->type = EXFAT_STREAM;
+	} else if (type == TYPE_EXTEND) {
+		ep->type = EXFAT_NAME;
+	} else if (type == TYPE_BITMAP) {
+		ep->type = EXFAT_BITMAP;
+	} else if (type == TYPE_UPCASE) {
+		ep->type = EXFAT_UPCASE;
+	} else if (type == TYPE_VOLUME) {
+		ep->type = EXFAT_VOLUME;
+	} else if (type == TYPE_DIR) {
+		ep->type = EXFAT_FILE;
+		ep->dentry.file.attr = cpu_to_le16(ATTR_SUBDIR);
+	} else if (type == TYPE_FILE) {
+		ep->type = EXFAT_FILE;
+		ep->dentry.file.attr = cpu_to_le16(ATTR_ARCHIVE);
+	}
+}
+
+static void exfat_init_stream_entry(struct exfat_dentry *ep,
+		unsigned char flags, unsigned int start_clu,
+		unsigned long long size)
+{
+	exfat_set_entry_type(ep, TYPE_STREAM);
+	ep->dentry.stream.flags = flags;
+	ep->dentry.stream.start_clu = cpu_to_le32(start_clu);
+	ep->dentry.stream.valid_size = cpu_to_le64(size);
+	ep->dentry.stream.size = cpu_to_le64(size);
+}
+
+static void exfat_init_name_entry(struct exfat_dentry *ep,
+		unsigned short *uniname)
+{
+	int i;
+
+	exfat_set_entry_type(ep, TYPE_EXTEND);
+	ep->dentry.name.flags = 0x0;
+
+	for (i = 0; i < EXFAT_FILE_NAME_LEN; i++) {
+		if (*uniname != 0x0) {
+			ep->dentry.name.unicode_0_14[i] = cpu_to_le16(*uniname);
+			uniname++;
+		} else {
+			ep->dentry.name.unicode_0_14[i] = 0x0;
+		}
+	}
+}
+
+int exfat_init_dir_entry(struct inode *inode, struct exfat_chain *p_dir,
+		int entry, unsigned int type, unsigned int start_clu,
+		unsigned long long size)
+{
+	struct super_block *sb = inode->i_sb;
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+	struct timespec64 ts = current_time(inode);
+	struct exfat_dentry *ep;
+	struct buffer_head *bh;
+
+	/*
+	 * We cannot use exfat_get_dentry_set here because file ep is not
+	 * initialized yet.
+	 */
+	ep = exfat_get_dentry(sb, p_dir, entry, &bh);
+	if (!ep)
+		return -EIO;
+
+	exfat_set_entry_type(ep, type);
+	exfat_set_entry_time(sbi, &ts,
+			&ep->dentry.file.create_tz,
+			&ep->dentry.file.create_time,
+			&ep->dentry.file.create_date,
+			&ep->dentry.file.create_time_cs);
+	exfat_set_entry_time(sbi, &ts,
+			&ep->dentry.file.modify_tz,
+			&ep->dentry.file.modify_time,
+			&ep->dentry.file.modify_date,
+			&ep->dentry.file.modify_time_cs);
+	exfat_set_entry_time(sbi, &ts,
+			&ep->dentry.file.access_tz,
+			&ep->dentry.file.access_time,
+			&ep->dentry.file.access_date,
+			NULL);
+
+	exfat_update_bh(bh, IS_DIRSYNC(inode));
+	brelse(bh);
+
+	ep = exfat_get_dentry(sb, p_dir, entry + 1, &bh);
+	if (!ep)
+		return -EIO;
+
+	exfat_init_stream_entry(ep,
+		(type == TYPE_FILE) ? ALLOC_FAT_CHAIN : ALLOC_NO_FAT_CHAIN,
+		start_clu, size);
+	exfat_update_bh(bh, IS_DIRSYNC(inode));
+	brelse(bh);
+
+	return 0;
+}
+
+int exfat_update_dir_chksum(struct inode *inode, struct exfat_chain *p_dir,
+		int entry)
+{
+	struct super_block *sb = inode->i_sb;
+	int ret = 0;
+	int i, num_entries;
+	u16 chksum;
+	struct exfat_dentry *ep, *fep;
+	struct buffer_head *fbh, *bh;
+
+	fep = exfat_get_dentry(sb, p_dir, entry, &fbh);
+	if (!fep)
+		return -EIO;
+
+	num_entries = fep->dentry.file.num_ext + 1;
+	chksum = exfat_calc_chksum16(fep, DENTRY_SIZE, 0, CS_DIR_ENTRY);
+
+	for (i = 1; i < num_entries; i++) {
+		ep = exfat_get_dentry(sb, p_dir, entry + i, &bh);
+		if (!ep) {
+			ret = -EIO;
+			goto release_fbh;
+		}
+		chksum = exfat_calc_chksum16(ep, DENTRY_SIZE, chksum,
+				CS_DEFAULT);
+		brelse(bh);
+	}
+
+	fep->dentry.file.checksum = cpu_to_le16(chksum);
+	exfat_update_bh(fbh, IS_DIRSYNC(inode));
+release_fbh:
+	brelse(fbh);
+	return ret;
+}
+
+static void exfat_free_benign_secondary_clusters(struct inode *inode,
+		struct exfat_dentry *ep)
+{
+	struct super_block *sb = inode->i_sb;
+	struct exfat_chain dir;
+	unsigned int start_clu =
+		le32_to_cpu(ep->dentry.generic_secondary.start_clu);
+	u64 size = le64_to_cpu(ep->dentry.generic_secondary.size);
+	unsigned char flags = ep->dentry.generic_secondary.flags;
+
+	if (!(flags & ALLOC_POSSIBLE) || !start_clu || !size)
+		return;
+
+	exfat_chain_set(&dir, start_clu,
+			EXFAT_B_TO_CLU_ROUND_UP(size, EXFAT_SB(sb)),
+			flags);
+	exfat_free_cluster(inode, &dir);
+}
+
+int exfat_init_ext_entry(struct inode *inode, struct exfat_chain *p_dir,
+		int entry, int num_entries, struct exfat_uni_name *p_uniname)
+{
+	struct super_block *sb = inode->i_sb;
+	int i;
+	unsigned short *uniname = p_uniname->name;
+	struct exfat_dentry *ep;
+	struct buffer_head *bh;
+	int sync = IS_DIRSYNC(inode);
+
+	ep = exfat_get_dentry(sb, p_dir, entry, &bh);
+	if (!ep)
+		return -EIO;
+
+	ep->dentry.file.num_ext = (unsigned char)(num_entries - 1);
+	exfat_update_bh(bh, sync);
+	brelse(bh);
+
+	ep = exfat_get_dentry(sb, p_dir, entry + 1, &bh);
+	if (!ep)
+		return -EIO;
+
+	ep->dentry.stream.name_len = p_uniname->name_len;
+	ep->dentry.stream.name_hash = cpu_to_le16(p_uniname->name_hash);
+	exfat_update_bh(bh, sync);
+	brelse(bh);
+
+	for (i = EXFAT_FIRST_CLUSTER; i < num_entries; i++) {
+		ep = exfat_get_dentry(sb, p_dir, entry + i, &bh);
+		if (!ep)
+			return -EIO;
+
+		if (exfat_get_entry_type(ep) & TYPE_BENIGN_SEC)
+			exfat_free_benign_secondary_clusters(inode, ep);
+
+		exfat_init_name_entry(ep, uniname);
+		exfat_update_bh(bh, sync);
+		brelse(bh);
+		uniname += EXFAT_FILE_NAME_LEN;
+	}
+
+	exfat_update_dir_chksum(inode, p_dir, entry);
+	return 0;
+}
+
+int exfat_remove_entries(struct inode *inode, struct exfat_chain *p_dir,
+		int entry, int order, int num_entries)
+{
+	struct super_block *sb = inode->i_sb;
+	int i;
+	struct exfat_dentry *ep;
+	struct buffer_head *bh;
+
+	for (i = order; i < num_entries; i++) {
+		ep = exfat_get_dentry(sb, p_dir, entry + i, &bh);
+		if (!ep)
+			return -EIO;
+
+		if (exfat_get_entry_type(ep) & TYPE_BENIGN_SEC)
+			exfat_free_benign_secondary_clusters(inode, ep);
+
+		exfat_set_entry_type(ep, TYPE_DELETED);
+		exfat_update_bh(bh, IS_DIRSYNC(inode));
+		brelse(bh);
+	}
+
+	return 0;
+}
+
+void exfat_update_dir_chksum_with_entry_set(struct exfat_entry_set_cache *es)
+{
+	int chksum_type = CS_DIR_ENTRY, i;
+	unsigned short chksum = 0;
+	struct exfat_dentry *ep;
+
+	for (i = ES_IDX_FILE; i < es->num_entries; i++) {
+		ep = exfat_get_dentry_cached(es, i);
+		chksum = exfat_calc_chksum16(ep, DENTRY_SIZE, chksum,
+					     chksum_type);
+		chksum_type = CS_DEFAULT;
+	}
+	ep = exfat_get_dentry_cached(es, ES_IDX_FILE);
+	ep->dentry.file.checksum = cpu_to_le16(chksum);
+	es->modified = true;
+}
+
+int exfat_put_dentry_set(struct exfat_entry_set_cache *es, int sync)
+{
+	int i, err = 0;
+
+	if (es->modified)
+		err = exfat_update_bhs(es->bh, es->num_bh, sync);
+
+	for (i = 0; i < es->num_bh; i++)
+		if (err)
+			bforget(es->bh[i]);
+		else
+			brelse(es->bh[i]);
+
+	if (IS_DYNAMIC_ES(es))
+		kfree(es->bh);
+
+	return err;
+}
+
+static int exfat_walk_fat_chain(struct super_block *sb,
+		struct exfat_chain *p_dir, unsigned int byte_offset,
+		unsigned int *clu)
+{
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+	unsigned int clu_offset;
+	unsigned int cur_clu;
+
+	clu_offset = EXFAT_B_TO_CLU(byte_offset, sbi);
+	cur_clu = p_dir->dir;
+
+	if (p_dir->flags == ALLOC_NO_FAT_CHAIN) {
+		cur_clu += clu_offset;
+	} else {
+		while (clu_offset > 0) {
+			if (exfat_get_next_cluster(sb, &cur_clu))
+				return -EIO;
+			if (cur_clu == EXFAT_EOF_CLUSTER) {
+				exfat_fs_error(sb,
+					"invalid dentry access beyond EOF (clu : %u, eidx : %d)",
+					p_dir->dir,
+					EXFAT_B_TO_DEN(byte_offset));
+				return -EIO;
+			}
+			clu_offset--;
+		}
+	}
+
+	*clu = cur_clu;
+	return 0;
+}
+
+static int exfat_find_location(struct super_block *sb, struct exfat_chain *p_dir,
+			       int entry, sector_t *sector, int *offset)
+{
+	int ret;
+	unsigned int off, clu = 0;
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+
+	off = EXFAT_DEN_TO_B(entry);
+
+	ret = exfat_walk_fat_chain(sb, p_dir, off, &clu);
+	if (ret)
+		return ret;
+
+	/* byte offset in cluster */
+	off = EXFAT_CLU_OFFSET(off, sbi);
+
+	/* byte offset in sector    */
+	*offset = EXFAT_BLK_OFFSET(off, sb);
+
+	/* sector offset in cluster */
+	*sector = EXFAT_B_TO_BLK(off, sb);
+	*sector += exfat_cluster_to_sector(sbi, clu);
+	return 0;
+}
+
+#define EXFAT_MAX_RA_SIZE     (128*1024)
+static int exfat_dir_readahead(struct super_block *sb, sector_t sec)
+{
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+	struct buffer_head *bh;
+	unsigned int max_ra_count = EXFAT_MAX_RA_SIZE >> sb->s_blocksize_bits;
+	unsigned int page_ra_count = PAGE_SIZE >> sb->s_blocksize_bits;
+	unsigned int adj_ra_count = max(sbi->sect_per_clus, page_ra_count);
+	unsigned int ra_count = min(adj_ra_count, max_ra_count);
+
+	/* Read-ahead is not required */
+	if (sbi->sect_per_clus == 1)
+		return 0;
+
+	if (sec < sbi->data_start_sector) {
+		exfat_err(sb, "requested sector is invalid(sect:%llu, root:%llu)",
+			  (unsigned long long)sec, sbi->data_start_sector);
+		return -EIO;
+	}
+
+	/* Not sector aligned with ra_count, resize ra_count to page size */
+	if ((sec - sbi->data_start_sector) & (ra_count - 1))
+		ra_count = page_ra_count;
+
+	bh = sb_find_get_block(sb, sec);
+	if (!bh || !buffer_uptodate(bh)) {
+		unsigned int i;
+
+		for (i = 0; i < ra_count; i++)
+			sb_breadahead(sb, (sector_t)(sec + i));
+	}
+	brelse(bh);
+	return 0;
+}
+
+struct exfat_dentry *exfat_get_dentry(struct super_block *sb,
+		struct exfat_chain *p_dir, int entry, struct buffer_head **bh)
+{
+	unsigned int dentries_per_page = EXFAT_B_TO_DEN(PAGE_SIZE);
+	int off;
+	sector_t sec;
+
+	if (p_dir->dir == DIR_DELETED) {
+		exfat_err(sb, "abnormal access to deleted dentry");
+		return NULL;
+	}
+
+	if (exfat_find_location(sb, p_dir, entry, &sec, &off))
+		return NULL;
+
+	if (p_dir->dir != EXFAT_FREE_CLUSTER &&
+			!(entry & (dentries_per_page - 1)))
+		exfat_dir_readahead(sb, sec);
+
+	*bh = sb_bread(sb, sec);
+	if (!*bh)
+		return NULL;
+
+	return (struct exfat_dentry *)((*bh)->b_data + off);
+}
+
+enum exfat_validate_dentry_mode {
+	ES_MODE_STARTED,
+	ES_MODE_GET_FILE_ENTRY,
+	ES_MODE_GET_STRM_ENTRY,
+	ES_MODE_GET_NAME_ENTRY,
+	ES_MODE_GET_CRITICAL_SEC_ENTRY,
+	ES_MODE_GET_BENIGN_SEC_ENTRY,
+};
+
+static bool exfat_validate_entry(unsigned int type,
+		enum exfat_validate_dentry_mode *mode)
+{
+	if (type == TYPE_UNUSED || type == TYPE_DELETED)
+		return false;
+
+	switch (*mode) {
+	case ES_MODE_STARTED:
+		if  (type != TYPE_FILE && type != TYPE_DIR)
+			return false;
+		*mode = ES_MODE_GET_FILE_ENTRY;
+		break;
+	case ES_MODE_GET_FILE_ENTRY:
+		if (type != TYPE_STREAM)
+			return false;
+		*mode = ES_MODE_GET_STRM_ENTRY;
+		break;
+	case ES_MODE_GET_STRM_ENTRY:
+		if (type != TYPE_EXTEND)
+			return false;
+		*mode = ES_MODE_GET_NAME_ENTRY;
+		break;
+	case ES_MODE_GET_NAME_ENTRY:
+		if (type & TYPE_BENIGN_SEC)
+			*mode = ES_MODE_GET_BENIGN_SEC_ENTRY;
+		else if (type != TYPE_EXTEND)
+			return false;
+		break;
+	case ES_MODE_GET_BENIGN_SEC_ENTRY:
+		/* Assume unreconized benign secondary entry */
+		if (!(type & TYPE_BENIGN_SEC))
+			return false;
+		break;
+	default:
+		return false;
+	}
+
+	return true;
+}
+
+struct exfat_dentry *exfat_get_dentry_cached(
+	struct exfat_entry_set_cache *es, int num)
+{
+	int off = es->start_off + num * DENTRY_SIZE;
+	struct buffer_head *bh = es->bh[EXFAT_B_TO_BLK(off, es->sb)];
+	char *p = bh->b_data + EXFAT_BLK_OFFSET(off, es->sb);
+
+	return (struct exfat_dentry *)p;
+}
+
+/*
+ * Returns a set of dentries for a file or dir.
+ *
+ * Note It provides a direct pointer to bh->data via exfat_get_dentry_cached().
+ * User should call exfat_get_dentry_set() after setting 'modified' to apply
+ * changes made in this entry set to the real device.
+ *
+ * in:
+ *   sb+p_dir+entry: indicates a file/dir
+ *   type:  specifies how many dentries should be included.
+ * return:
+ *   pointer of entry set on success,
+ *   NULL on failure.
+ */
+int exfat_get_dentry_set(struct exfat_entry_set_cache *es,
+		struct super_block *sb, struct exfat_chain *p_dir, int entry,
+		unsigned int type)
+{
+	int ret, i, num_bh;
+	unsigned int off;
+	sector_t sec;
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+	struct exfat_dentry *ep;
+	int num_entries;
+	enum exfat_validate_dentry_mode mode = ES_MODE_STARTED;
+	struct buffer_head *bh;
+
+	if (p_dir->dir == DIR_DELETED) {
+		exfat_err(sb, "access to deleted dentry");
+		return -EIO;
+	}
+
+	ret = exfat_find_location(sb, p_dir, entry, &sec, &off);
+	if (ret)
+		return ret;
+
+	memset(es, 0, sizeof(*es));
+	es->sb = sb;
+	es->modified = false;
+	es->start_off = off;
+	es->bh = es->__bh;
+
+	bh = sb_bread(sb, sec);
+	if (!bh)
+		return -EIO;
+	es->bh[es->num_bh++] = bh;
+
+	ep = exfat_get_dentry_cached(es, ES_IDX_FILE);
+	if (!exfat_validate_entry(exfat_get_entry_type(ep), &mode))
+		goto put_es;
+
+	num_entries = type == ES_ALL_ENTRIES ?
+		ep->dentry.file.num_ext + 1 : type;
+	es->num_entries = num_entries;
+
+	num_bh = EXFAT_B_TO_BLK_ROUND_UP(off + num_entries * DENTRY_SIZE, sb);
+	if (num_bh > ARRAY_SIZE(es->__bh)) {
+		es->bh = kmalloc_array(num_bh, sizeof(*es->bh), GFP_KERNEL);
+		if (!es->bh) {
+			brelse(bh);
+			return -ENOMEM;
+		}
+		es->bh[0] = bh;
+	}
+
+	for (i = 1; i < num_bh; i++) {
+		/* get the next sector */
+		if (exfat_is_last_sector_in_cluster(sbi, sec)) {
+			unsigned int clu = exfat_sector_to_cluster(sbi, sec);
+
+			if (p_dir->flags == ALLOC_NO_FAT_CHAIN)
+				clu++;
+			else if (exfat_get_next_cluster(sb, &clu))
+				goto put_es;
+			sec = exfat_cluster_to_sector(sbi, clu);
+		} else {
+			sec++;
+		}
+
+		bh = sb_bread(sb, sec);
+		if (!bh)
+			goto put_es;
+		es->bh[es->num_bh++] = bh;
+	}
+
+	/* validate cached dentries */
+	for (i = ES_IDX_STREAM; i < num_entries; i++) {
+		ep = exfat_get_dentry_cached(es, i);
+		if (!exfat_validate_entry(exfat_get_entry_type(ep), &mode))
+			goto put_es;
+	}
+	return 0;
+
+put_es:
+	exfat_put_dentry_set(es, false);
+	return -EIO;
+}
+
+static inline void exfat_reset_empty_hint(struct exfat_hint_femp *hint_femp)
+{
+	hint_femp->eidx = EXFAT_HINT_NONE;
+	hint_femp->count = 0;
+}
+
+static inline void exfat_set_empty_hint(struct exfat_inode_info *ei,
+		struct exfat_hint_femp *candi_empty, struct exfat_chain *clu,
+		int dentry, int num_entries, int entry_type)
+{
+	if (ei->hint_femp.eidx == EXFAT_HINT_NONE ||
+	    ei->hint_femp.eidx > dentry) {
+		int total_entries = EXFAT_B_TO_DEN(i_size_read(&ei->vfs_inode));
+
+		if (candi_empty->count == 0) {
+			candi_empty->cur = *clu;
+			candi_empty->eidx = dentry;
+		}
+
+		if (entry_type == TYPE_UNUSED)
+			candi_empty->count += total_entries - dentry;
+		else
+			candi_empty->count++;
+
+		if (candi_empty->count == num_entries ||
+		    candi_empty->count + candi_empty->eidx == total_entries)
+			ei->hint_femp = *candi_empty;
+	}
+}
+
+enum {
+	DIRENT_STEP_FILE,
+	DIRENT_STEP_STRM,
+	DIRENT_STEP_NAME,
+	DIRENT_STEP_SECD,
+};
+
+/*
+ * @ei:         inode info of parent directory
+ * @p_dir:      directory structure of parent directory
+ * @num_entries:entry size of p_uniname
+ * @hint_opt:   If p_uniname is found, filled with optimized dir/entry
+ *              for traversing cluster chain.
+ * @return:
+ *   >= 0:      file directory entry position where the name exists
+ *   -ENOENT:   entry with the name does not exist
+ *   -EIO:      I/O error
+ */
+int exfat_find_dir_entry(struct super_block *sb, struct exfat_inode_info *ei,
+		struct exfat_chain *p_dir, struct exfat_uni_name *p_uniname,
+		struct exfat_hint *hint_opt)
+{
+	int i, rewind = 0, dentry = 0, end_eidx = 0, num_ext = 0, len;
+	int order, step, name_len = 0;
+	int dentries_per_clu;
+	unsigned int entry_type;
+	unsigned short *uniname = NULL;
+	struct exfat_chain clu;
+	struct exfat_hint *hint_stat = &ei->hint_stat;
+	struct exfat_hint_femp candi_empty;
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+	int num_entries = exfat_calc_num_entries(p_uniname);
+
+	if (num_entries < 0)
+		return num_entries;
+
+	dentries_per_clu = sbi->dentries_per_clu;
+
+	exfat_chain_dup(&clu, p_dir);
+
+	if (hint_stat->eidx) {
+		clu.dir = hint_stat->clu;
+		dentry = hint_stat->eidx;
+		end_eidx = dentry;
+	}
+
+	exfat_reset_empty_hint(&ei->hint_femp);
+
+rewind:
+	order = 0;
+	step = DIRENT_STEP_FILE;
+	exfat_reset_empty_hint(&candi_empty);
+
+	while (clu.dir != EXFAT_EOF_CLUSTER) {
+		i = dentry & (dentries_per_clu - 1);
+		for (; i < dentries_per_clu; i++, dentry++) {
+			struct exfat_dentry *ep;
+			struct buffer_head *bh;
+
+			if (rewind && dentry == end_eidx)
+				goto not_found;
+
+			ep = exfat_get_dentry(sb, &clu, i, &bh);
+			if (!ep)
+				return -EIO;
+
+			entry_type = exfat_get_entry_type(ep);
+
+			if (entry_type == TYPE_UNUSED ||
+			    entry_type == TYPE_DELETED) {
+				step = DIRENT_STEP_FILE;
+
+				exfat_set_empty_hint(ei, &candi_empty, &clu,
+						dentry, num_entries,
+						entry_type);
+
+				brelse(bh);
+				if (entry_type == TYPE_UNUSED)
+					goto not_found;
+				continue;
+			}
+
+			exfat_reset_empty_hint(&candi_empty);
+
+			if (entry_type == TYPE_FILE || entry_type == TYPE_DIR) {
+				step = DIRENT_STEP_FILE;
+				hint_opt->clu = clu.dir;
+				hint_opt->eidx = i;
+				num_ext = ep->dentry.file.num_ext;
+				step = DIRENT_STEP_STRM;
+				brelse(bh);
+				continue;
+			}
+
+			if (entry_type == TYPE_STREAM) {
+				u16 name_hash;
+
+				if (step != DIRENT_STEP_STRM) {
+					step = DIRENT_STEP_FILE;
+					brelse(bh);
+					continue;
+				}
+				step = DIRENT_STEP_FILE;
+				name_hash = le16_to_cpu(
+						ep->dentry.stream.name_hash);
+				if (p_uniname->name_hash == name_hash &&
+				    p_uniname->name_len ==
+						ep->dentry.stream.name_len) {
+					step = DIRENT_STEP_NAME;
+					order = 1;
+					name_len = 0;
+				}
+				brelse(bh);
+				continue;
+			}
+
+			brelse(bh);
+			if (entry_type == TYPE_EXTEND) {
+				unsigned short entry_uniname[16], unichar;
+
+				if (step != DIRENT_STEP_NAME ||
+				    name_len >= MAX_NAME_LENGTH) {
+					step = DIRENT_STEP_FILE;
+					continue;
+				}
+
+				if (++order == 2)
+					uniname = p_uniname->name;
+				else
+					uniname += EXFAT_FILE_NAME_LEN;
+
+				len = exfat_extract_uni_name(ep, entry_uniname);
+				name_len += len;
+
+				unichar = *(uniname+len);
+				*(uniname+len) = 0x0;
+
+				if (exfat_uniname_ncmp(sb, uniname,
+					entry_uniname, len)) {
+					step = DIRENT_STEP_FILE;
+				} else if (p_uniname->name_len == name_len) {
+					if (order == num_ext)
+						goto found;
+					step = DIRENT_STEP_SECD;
+				}
+
+				*(uniname+len) = unichar;
+				continue;
+			}
+
+			if (entry_type &
+					(TYPE_CRITICAL_SEC | TYPE_BENIGN_SEC)) {
+				if (step == DIRENT_STEP_SECD) {
+					if (++order == num_ext)
+						goto found;
+					continue;
+				}
+			}
+			step = DIRENT_STEP_FILE;
+		}
+
+		if (clu.flags == ALLOC_NO_FAT_CHAIN) {
+			if (--clu.size > 0)
+				clu.dir++;
+			else
+				clu.dir = EXFAT_EOF_CLUSTER;
+		} else {
+			if (exfat_get_next_cluster(sb, &clu.dir))
+				return -EIO;
+		}
+	}
+
+not_found:
+	/*
+	 * We started at not 0 index,so we should try to find target
+	 * from 0 index to the index we started at.
+	 */
+	if (!rewind && end_eidx) {
+		rewind = 1;
+		dentry = 0;
+		clu.dir = p_dir->dir;
+		goto rewind;
+	}
+
+	/*
+	 * set the EXFAT_EOF_CLUSTER flag to avoid search
+	 * from the beginning again when allocated a new cluster
+	 */
+	if (ei->hint_femp.eidx == EXFAT_HINT_NONE) {
+		ei->hint_femp.cur.dir = EXFAT_EOF_CLUSTER;
+		ei->hint_femp.eidx = p_dir->size * dentries_per_clu;
+		ei->hint_femp.count = 0;
+	}
+
+	/* initialized hint_stat */
+	hint_stat->clu = p_dir->dir;
+	hint_stat->eidx = 0;
+	return -ENOENT;
+
+found:
+	/* next dentry we'll find is out of this cluster */
+	if (!((dentry + 1) & (dentries_per_clu - 1))) {
+		int ret = 0;
+
+		if (clu.flags == ALLOC_NO_FAT_CHAIN) {
+			if (--clu.size > 0)
+				clu.dir++;
+			else
+				clu.dir = EXFAT_EOF_CLUSTER;
+		} else {
+			ret = exfat_get_next_cluster(sb, &clu.dir);
+		}
+
+		if (ret || clu.dir == EXFAT_EOF_CLUSTER) {
+			/* just initialized hint_stat */
+			hint_stat->clu = p_dir->dir;
+			hint_stat->eidx = 0;
+			return (dentry - num_ext);
+		}
+	}
+
+	hint_stat->clu = clu.dir;
+	hint_stat->eidx = dentry + 1;
+	return dentry - num_ext;
+}
+
+int exfat_count_ext_entries(struct super_block *sb, struct exfat_chain *p_dir,
+		int entry, struct exfat_dentry *ep)
+{
+	int i, count = 0;
+	unsigned int type;
+	struct exfat_dentry *ext_ep;
+	struct buffer_head *bh;
+
+	for (i = 0, entry++; i < ep->dentry.file.num_ext; i++, entry++) {
+		ext_ep = exfat_get_dentry(sb, p_dir, entry, &bh);
+		if (!ext_ep)
+			return -EIO;
+
+		type = exfat_get_entry_type(ext_ep);
+		brelse(bh);
+		if (type & TYPE_CRITICAL_SEC || type & TYPE_BENIGN_SEC)
+			count++;
+	}
+	return count;
+}
+
+int exfat_count_dir_entries(struct super_block *sb, struct exfat_chain *p_dir)
+{
+	int i, count = 0;
+	int dentries_per_clu;
+	unsigned int entry_type;
+	struct exfat_chain clu;
+	struct exfat_dentry *ep;
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+	struct buffer_head *bh;
+
+	dentries_per_clu = sbi->dentries_per_clu;
+
+	exfat_chain_dup(&clu, p_dir);
+
+	while (clu.dir != EXFAT_EOF_CLUSTER) {
+		for (i = 0; i < dentries_per_clu; i++) {
+			ep = exfat_get_dentry(sb, &clu, i, &bh);
+			if (!ep)
+				return -EIO;
+			entry_type = exfat_get_entry_type(ep);
+			brelse(bh);
+
+			if (entry_type == TYPE_UNUSED)
+				return count;
+			if (entry_type != TYPE_DIR)
+				continue;
+			count++;
+		}
+
+		if (clu.flags == ALLOC_NO_FAT_CHAIN) {
+			if (--clu.size > 0)
+				clu.dir++;
+			else
+				clu.dir = EXFAT_EOF_CLUSTER;
+		} else {
+			if (exfat_get_next_cluster(sb, &(clu.dir)))
+				return -EIO;
+		}
+	}
+
+	return count;
+}