X-Git-Url: https://git.sven.stormbind.net/?a=blobdiff_plain;f=fsck%2Ffsck.c;h=00d1ca7f2c3620770547fc014ffc14a2d99d70e3;hb=HEAD;hp=2a13f437c010c7601c063b2c148e4c8098dde60f;hpb=f7feb8f190bd23ec253bf9fe705738049d9cedd7;p=sven%2Fexfatprogs.git

diff --git a/fsck/fsck.c b/fsck/fsck.c
index 2a13f43..77272aa 100644
--- a/fsck/fsck.c
+++ b/fsck/fsck.c
@@ -15,8 +15,10 @@
 
 #include "exfat_ondisk.h"
 #include "libexfat.h"
-#include "fsck.h"
 #include "repair.h"
+#include "exfat_fs.h"
+#include "exfat_dir.h"
+#include "fsck.h"
 
 struct fsck_user_input {
 	struct exfat_user_input		ei;
@@ -25,23 +27,6 @@ struct fsck_user_input {
 
 #define EXFAT_MAX_UPCASE_CHARS	0x10000
 
-#ifdef WORDS_BIGENDIAN
-typedef __u8	bitmap_t;
-#else
-typedef __u32	bitmap_t;
-#endif
-
-#define BITS_PER	(sizeof(bitmap_t) * 8)
-#define BIT_MASK(__c)	(1 << ((__c) % BITS_PER))
-#define BIT_ENTRY(__c)	((__c) / BITS_PER)
-
-#define EXFAT_BITMAP_SIZE(__c_count)	\
-	(DIV_ROUND_UP(__c_count, BITS_PER) * sizeof(bitmap_t))
-#define EXFAT_BITMAP_GET(__bmap, __c)	\
-			((__bmap)[BIT_ENTRY(__c)] & BIT_MASK(__c))
-#define EXFAT_BITMAP_SET(__bmap, __c)	\
-			((__bmap)[BIT_ENTRY(__c)] |= BIT_MASK(__c))
-
 #define FSCK_EXIT_NO_ERRORS		0x00
 #define FSCK_EXIT_CORRECTED		0x01
 #define FSCK_EXIT_NEED_REBOOT		0x02
@@ -54,16 +39,11 @@ typedef __u32	bitmap_t;
 struct exfat_stat {
 	long		dir_count;
 	long		file_count;
-	long		dir_free_count;
-	long		file_free_count;
-};
-
-struct path_resolve_ctx {
-	struct exfat_inode	*ancestors[255];
-	__le16			utf16_path[PATH_MAX + 2];
-	char			local_path[PATH_MAX * MB_LEN_MAX + 1];
+	long		error_count;
+	long		fixed_count;
 };
 
+struct exfat_fsck exfat_fsck;
 struct exfat_stat exfat_stat;
 struct path_resolve_ctx path_resolve_ctx;
 
@@ -71,10 +51,13 @@ static struct option opts[] = {
 	{"repair",	no_argument,	NULL,	'r' },
 	{"repair-yes",	no_argument,	NULL,	'y' },
 	{"repair-no",	no_argument,	NULL,	'n' },
+	{"repair-auto",	no_argument,	NULL,	'p' },
+	{"rescue",	no_argument,	NULL,	's' },
 	{"version",	no_argument,	NULL,	'V' },
 	{"verbose",	no_argument,	NULL,	'v' },
 	{"help",	no_argument,	NULL,	'h' },
 	{"?",		no_argument,	NULL,	'?' },
+	{"ignore-bad-fs",	no_argument,	NULL,	'b' },
 	{NULL,		0,		NULL,	 0  }
 };
 
@@ -84,6 +67,10 @@ static void usage(char *name)
 	fprintf(stderr, "\t-r | --repair        Repair interactively\n");
 	fprintf(stderr, "\t-y | --repair-yes    Repair without ask\n");
 	fprintf(stderr, "\t-n | --repair-no     No repair\n");
+	fprintf(stderr, "\t-p | --repair-auto   Repair automatically\n");
+	fprintf(stderr, "\t-a                   Repair automatically\n");
+	fprintf(stderr, "\t-b | --ignore-bad-fs Try to recover even if exfat is not found\n");
+	fprintf(stderr, "\t-s | --rescue        Assign orphaned clusters to files\n");
 	fprintf(stderr, "\t-V | --version       Show version\n");
 	fprintf(stderr, "\t-v | --verbose       Print debug\n");
 	fprintf(stderr, "\t-h | --help          Show help\n");
@@ -91,780 +78,776 @@ static void usage(char *name)
 	exit(FSCK_EXIT_SYNTAX_ERROR);
 }
 
-static struct exfat_inode *alloc_exfat_inode(__u16 attr)
+#define fsck_err(parent, inode, fmt, ...)		\
+({							\
+		exfat_resolve_path_parent(&path_resolve_ctx,	\
+			parent, inode);			\
+		exfat_err("ERROR: %s: " fmt,		\
+			path_resolve_ctx.local_path,	\
+			##__VA_ARGS__);			\
+})
+
+#define repair_file_ask(iter, inode, code, fmt, ...)	\
+({							\
+		if (inode)						\
+			exfat_resolve_path_parent(&path_resolve_ctx,	\
+					    (iter)->parent, inode);	\
+		else							\
+			exfat_resolve_path(&path_resolve_ctx,		\
+				     (iter)->parent);			\
+		exfat_repair_ask(&exfat_fsck, code,			\
+				 "ERROR: %s: " fmt " at %#" PRIx64,	\
+				 path_resolve_ctx.local_path,		\
+				 ##__VA_ARGS__,				\
+				 exfat_de_iter_device_offset(iter));	\
+})
+
+static int check_clus_chain(struct exfat_de_iter *de_iter,
+			    struct exfat_inode *node)
 {
-	struct exfat_inode *node;
-	int size;
-
-	size = offsetof(struct exfat_inode, name) + NAME_BUFFER_SIZE;
-	node = (struct exfat_inode *)calloc(1, size);
-	if (!node) {
-		exfat_err("failed to allocate exfat_node\n");
-		return NULL;
-	}
-
-	node->parent = NULL;
-	INIT_LIST_HEAD(&node->children);
-	INIT_LIST_HEAD(&node->sibling);
-	INIT_LIST_HEAD(&node->list);
-
-	node->last_pclus = EXFAT_EOF_CLUSTER;
-	node->attr = attr;
-	if (attr & ATTR_SUBDIR)
-		exfat_stat.dir_count++;
-	else
-		exfat_stat.file_count++;
-	return node;
-}
+	struct exfat *exfat = de_iter->exfat;
+	struct exfat_dentry *stream_de;
+	clus_t clus, prev, next;
+	uint64_t count, max_count;
 
-static void free_exfat_inode(struct exfat_inode *node)
-{
-	if (node->attr & ATTR_SUBDIR)
-		exfat_stat.dir_free_count++;
-	else
-		exfat_stat.file_free_count++;
-	free(node);
-}
+	clus = node->first_clus;
+	prev = EXFAT_EOF_CLUSTER;
+	count = 0;
+	max_count = DIV_ROUND_UP(node->size, exfat->clus_size);
 
-static void inode_free_children(struct exfat_inode *dir, bool file_only)
-{
-	struct exfat_inode *node, *i;
+	if (node->size == 0 && node->first_clus == EXFAT_FREE_CLUSTER)
+		return 0;
 
-	list_for_each_entry_safe(node, i, &dir->children, sibling) {
-		if (file_only) {
-			if (!(node->attr & ATTR_SUBDIR)) {
-				list_del(&node->sibling);
-				free_exfat_inode(node);
-			}
-		} else {
-			list_del(&node->sibling);
-			list_del(&node->list);
-			free_exfat_inode(node);
-		}
+	/* the first cluster is wrong */
+	if ((node->size == 0 && node->first_clus != EXFAT_FREE_CLUSTER) ||
+	    (node->size > 0 && !exfat_heap_clus(exfat, node->first_clus))) {
+		if (repair_file_ask(de_iter, node,
+				    ER_FILE_FIRST_CLUS,
+				    "size %#" PRIx64 ", but the first cluster %#x",
+				    node->size, node->first_clus))
+			goto truncate_file;
+		else
+			return -EINVAL;
 	}
-}
 
-static void inode_free_file_children(struct exfat_inode *dir)
-{
-	inode_free_children(dir, true);
-}
-
-/* delete @child and all ancestors that does not have
- * children
- */
-static void inode_free_ancestors(struct exfat_inode *child)
-{
-	struct exfat_inode *parent;
-
-	if (!list_empty(&child->children))
-		return;
-
-	do {
-		if (!(child->attr & ATTR_SUBDIR)) {
-			exfat_err("not directory.\n");
-			return;
+	while (clus != EXFAT_EOF_CLUSTER) {
+		if (count >= max_count) {
+			if (node->is_contiguous)
+				break;
+			if (repair_file_ask(de_iter, node,
+					    ER_FILE_SMALLER_SIZE,
+					    "more clusters are allocated. truncate to %"
+					    PRIu64 " bytes",
+					    count * exfat->clus_size))
+				goto truncate_file;
+			else
+				return -EINVAL;
 		}
 
-		parent = child->parent;
-		list_del(&child->sibling);
-		free_exfat_inode(child);
-
-		child = parent;
-	} while (child && list_empty(&child->children));
+		/*
+		 * This cluster is already allocated. it may be shared with
+		 * the other file, or there is a loop in cluster chain.
+		 */
+		if (exfat_bitmap_get(exfat->alloc_bitmap, clus)) {
+			if (repair_file_ask(de_iter, node,
+					    ER_FILE_DUPLICATED_CLUS,
+					    "cluster is already allocated for the other file. truncated to %"
+					    PRIu64 " bytes",
+					    count * exfat->clus_size))
+				goto truncate_file;
+			else
+				return -EINVAL;
+		}
 
-	return;
-}
+		if (!exfat_bitmap_get(exfat->disk_bitmap, clus)) {
+			if (!repair_file_ask(de_iter, node,
+					     ER_FILE_INVALID_CLUS,
+					     "cluster %#x is marked as free",
+					     clus))
+				return -EINVAL;
+		}
 
-static struct exfat *alloc_exfat(struct exfat_blk_dev *bd)
-{
-	struct exfat *exfat;
+		/* This cluster is allocated or not */
+		if (exfat_get_inode_next_clus(exfat, node, clus, &next))
+			goto truncate_file;
+		if (next == EXFAT_BAD_CLUSTER) {
+			if (repair_file_ask(de_iter, node,
+					    ER_FILE_INVALID_CLUS,
+					    "BAD cluster. truncate to %"
+					    PRIu64 " bytes",
+					    count * exfat->clus_size))
+				goto truncate_file;
+			else
+				return -EINVAL;
+		} else if (!node->is_contiguous) {
+			if (next != EXFAT_EOF_CLUSTER &&
+			    !exfat_heap_clus(exfat, next)) {
+				if (repair_file_ask(de_iter, node,
+						    ER_FILE_INVALID_CLUS,
+						    "broken cluster chain. truncate to %"
+						    PRIu64 " bytes",
+						    (count + 1) * exfat->clus_size)) {
+					count++;
+					prev = clus;
+					exfat_bitmap_set(exfat->alloc_bitmap,
+							 clus);
+					goto truncate_file;
+				} else {
+					return -EINVAL;
+				}
+			}
+		}
 
-	exfat = (struct exfat *)calloc(1, sizeof(*exfat));
-	if (!exfat) {
-		exfat_err("failed to allocate exfat\n");
-		return NULL;
+		count++;
+		exfat_bitmap_set(exfat->alloc_bitmap, clus);
+		prev = clus;
+		clus = next;
 	}
 
-	exfat->blk_dev = bd;
-	INIT_LIST_HEAD(&exfat->dir_list);
-	return exfat;
-}
-
-static void free_exfat(struct exfat *exfat)
-{
-	if (exfat) {
-		if (exfat->bs)
-			free(exfat->bs);
-		if (exfat->de_iter.dentries)
-			free(exfat->de_iter.dentries);
-		if (exfat->alloc_bitmap)
-			free(exfat->alloc_bitmap);
-		free(exfat);
+	if (count < max_count) {
+		if (repair_file_ask(de_iter, node, ER_FILE_LARGER_SIZE,
+				    "less clusters are allocated. truncates to %"
+				    PRIu64 " bytes",
+				    count * exfat->clus_size))
+			goto truncate_file;
+		else
+			return -EINVAL;
 	}
-}
 
-static void exfat_free_dir_list(struct exfat *exfat)
-{
-	struct exfat_inode *dir, *i;
-
-	list_for_each_entry_safe(dir, i, &exfat->dir_list, list) {
-		inode_free_file_children(dir);
-		list_del(&dir->list);
-		free_exfat_inode(dir);
+	return 0;
+truncate_file:
+	node->size = count * exfat->clus_size;
+	if (!exfat_heap_clus(exfat, prev))
+		node->first_clus = EXFAT_FREE_CLUSTER;
+
+	exfat_de_iter_get_dirty(de_iter, 1, &stream_de);
+	if (count * exfat->clus_size <
+	    le64_to_cpu(stream_de->stream_valid_size))
+		stream_de->stream_valid_size = cpu_to_le64(
+							   count * exfat->clus_size);
+	if (!exfat_heap_clus(exfat, prev))
+		stream_de->stream_start_clu = EXFAT_FREE_CLUSTER;
+	stream_de->stream_size = cpu_to_le64(
+					     count * exfat->clus_size);
+
+	/* remaining clusters will be freed while FAT is compared with
+	 * alloc_bitmap.
+	 */
+	if (!node->is_contiguous && exfat_heap_clus(exfat, prev)) {
+		if (exfat_set_fat(exfat, prev, EXFAT_EOF_CLUSTER))
+			return -EIO;
 	}
+	return 1;
 }
 
-static inline bool exfat_invalid_clus(struct exfat *exfat, clus_t clus)
+static int root_check_clus_chain(struct exfat *exfat,
+				 struct exfat_inode *node,
+				 clus_t *clus_count)
 {
-	return clus < EXFAT_FIRST_CLUSTER ||
-	(clus - EXFAT_FIRST_CLUSTER) > le32_to_cpu(exfat->bs->bsx.clu_count);
-}
-
-static int inode_get_clus_next(struct exfat *exfat, struct exfat_inode *node,
-				clus_t clus, clus_t *next)
-{
-	off_t offset;
-
-	if (exfat_invalid_clus(exfat, clus))
-		return -EINVAL;
-
-	if (node->is_contiguous) {
-		*next = clus + 1;
-		return 0;
-	}
+	clus_t clus, next, prev = EXFAT_EOF_CLUSTER;
 
-	offset = le32_to_cpu(exfat->bs->bsx.fat_offset) <<
-				exfat->bs->bsx.sect_size_bits;
-	offset += sizeof(clus_t) * clus;
-
-	if (exfat_read(exfat->blk_dev->dev_fd, next, sizeof(*next), offset)
-			!= sizeof(*next))
-		return -EIO;
-	*next = le32_to_cpu(*next);
-	return 0;
-}
-
-static bool inode_check_clus_chain(struct exfat *exfat, struct exfat_inode *node)
-{
-	clus_t clus;
-	clus_t clus_count;
+	if (!exfat_heap_clus(exfat, node->first_clus))
+		goto out_trunc;
 
 	clus = node->first_clus;
-	clus_count = DIV_ROUND_UP(node->size, EXFAT_CLUSTER_SIZE(exfat->bs));
-
-	while (clus_count--) {
-		if (exfat_invalid_clus(exfat, clus)) {
-			exfat_err("bad cluster. 0x%x\n", clus);
-			return false;
-		}
-
-		if (!EXFAT_BITMAP_GET(exfat->alloc_bitmap,
-					clus - EXFAT_FIRST_CLUSTER)) {
-			exfat_err(
-				"cluster allocated, but not in bitmap. 0x%x\n",
-				clus);
-			return false;
-		}
+	*clus_count = 0;
 
-		if (inode_get_clus_next(exfat, node, clus, &clus) != 0) {
-			exfat_err(
-				"broken cluster chain. (previous cluster 0x%x)\n",
-				clus);
-			return false;
+	do {
+		if (exfat_bitmap_get(exfat->alloc_bitmap, clus)) {
+			if (exfat_repair_ask(&exfat_fsck,
+					     ER_FILE_DUPLICATED_CLUS,
+					     "ERROR: the cluster chain of root is cyclic"))
+				goto out_trunc;
+			return -EINVAL;
 		}
-	}
-	return true;
-}
 
-static bool inode_get_clus_count(struct exfat *exfat, struct exfat_inode *node,
-							clus_t *clus_count)
-{
-	clus_t clus;
-
-	clus = node->first_clus;
-	*clus_count = 0;
+		exfat_bitmap_set(exfat->alloc_bitmap, clus);
 
-	do {
-		if (exfat_invalid_clus(exfat, clus)) {
-			exfat_err("bad cluster. 0x%x\n", clus);
-			return false;
+		if (exfat_get_inode_next_clus(exfat, node, clus, &next)) {
+			exfat_err("ERROR: failed to read the fat entry of root");
+			goto out_trunc;
 		}
 
-		if (inode_get_clus_next(exfat, node, clus, &clus) != 0) {
-			exfat_err(
-				"broken cluster chain. (previous cluster 0x%x)\n",
-				clus);
-			return false;
+		if (next != EXFAT_EOF_CLUSTER && !exfat_heap_clus(exfat, next)) {
+			if (exfat_repair_ask(&exfat_fsck,
+					     ER_FILE_INVALID_CLUS,
+					     "ERROR: the cluster chain of root is broken")) {
+				if (next != EXFAT_BAD_CLUSTER) {
+					prev = clus;
+					(*clus_count)++;
+				}
+				goto out_trunc;
+			}
+			return -EINVAL;
 		}
 
+		prev = clus;
+		clus = next;
 		(*clus_count)++;
 	} while (clus != EXFAT_EOF_CLUSTER);
-	return true;
-}
-
-static off_t exfat_s2o(struct exfat *exfat, off_t sect)
-{
-	return sect << exfat->bs->bsx.sect_size_bits;
-}
 
-static off_t exfat_c2o(struct exfat *exfat, unsigned int clus)
-{
-	if (clus < EXFAT_FIRST_CLUSTER)
-		return ~0L;
-
-	return exfat_s2o(exfat, le32_to_cpu(exfat->bs->bsx.clu_offset) +
-				((clus - EXFAT_FIRST_CLUSTER) <<
-				 exfat->bs->bsx.sect_per_clus_bits));
+	return 0;
+out_trunc:
+	if (!exfat_heap_clus(exfat, prev)) {
+		exfat_err("ERROR: the start cluster of root is wrong\n");
+		return -EINVAL;
+	}
+	node->size = *clus_count * exfat->clus_size;
+	return exfat_set_fat(exfat, prev, EXFAT_EOF_CLUSTER);
 }
 
-static ssize_t exfat_file_read(struct exfat *exfat, struct exfat_inode *node,
-			void *buf, size_t total_size, off_t file_offset)
+static int boot_region_checksum(int dev_fd,
+				int bs_offset, unsigned int sect_size)
 {
-	size_t clus_size;
-	clus_t start_l_clus, l_clus, p_clus;
-	unsigned int clus_offset;
-	int ret;
-	off_t device_offset;
-	ssize_t read_size;
-	size_t remain_size;
-
-	if (file_offset >= (off_t)node->size)
-		return EOF;
-
-	clus_size = EXFAT_CLUSTER_SIZE(exfat->bs);
-	total_size = MIN(total_size, node->size - file_offset);
-	remain_size = total_size;
+	void *sect;
+	unsigned int i;
+	uint32_t checksum;
+	int ret = 0;
 
-	if (remain_size == 0)
-		return 0;
+	sect = malloc(sect_size);
+	if (!sect)
+		return -ENOMEM;
 
-	start_l_clus = file_offset / clus_size;
-	clus_offset = file_offset % clus_size;
-	if (start_l_clus >= node->last_lclus &&
-			node->last_pclus != EXFAT_EOF_CLUSTER) {
-		l_clus = node->last_lclus;
-		p_clus = node->last_pclus;
-	} else {
-		l_clus = 0;
-		p_clus = node->first_clus;
+	checksum = 0;
+	for (i = 0; i < 11; i++) {
+		if (exfat_read(dev_fd, sect, sect_size,
+				bs_offset * sect_size + i * sect_size) !=
+				(ssize_t)sect_size) {
+			exfat_err("failed to read boot region\n");
+			ret = -EIO;
+			goto out;
+		}
+		boot_calc_checksum(sect, sect_size, i == 0, &checksum);
 	}
 
-	while (p_clus != EXFAT_EOF_CLUSTER) {
-		if (exfat_invalid_clus(exfat, p_clus))
-			return -EINVAL;
-		if (l_clus < start_l_clus)
-			goto next_clus;
-
-		read_size = MIN(remain_size, clus_size - clus_offset);
-		device_offset = exfat_c2o(exfat, p_clus) + clus_offset;
-		if (exfat_read(exfat->blk_dev->dev_fd, buf, read_size,
-					device_offset) != read_size)
-			return -EIO;
+	if (exfat_read(dev_fd, sect, sect_size,
+			bs_offset * sect_size + 11 * sect_size) !=
+			(ssize_t)sect_size) {
+		exfat_err("failed to read a boot checksum sector\n");
+		ret = -EIO;
+		goto out;
+	}
 
-		clus_offset = 0;
-		buf = (char *)buf + read_size;
-		remain_size -= read_size;
-		if (remain_size == 0)
+	for (i = 0; i < sect_size/sizeof(checksum); i++) {
+		if (le32_to_cpu(((__le32 *)sect)[i]) != checksum) {
+			exfat_err("checksum of boot region is not correct. %#x, but expected %#x\n",
+				le32_to_cpu(((__le32 *)sect)[i]), checksum);
+			ret = -EINVAL;
 			goto out;
-
-next_clus:
-		l_clus++;
-		ret = inode_get_clus_next(exfat, node, p_clus, &p_clus);
-		if (ret)
-			return ret;
+		}
 	}
 out:
-	node->last_lclus = l_clus;
-	node->last_pclus = p_clus;
-	return total_size - remain_size;
+	free(sect);
+	return ret;
 }
 
-static int boot_region_checksum(struct exfat *exfat)
+static int exfat_mark_volume_dirty(struct exfat *exfat, bool dirty)
 {
-	__le32 checksum;
-	unsigned short size;
-	void *sect;
-	unsigned int i;
-
-	size = EXFAT_SECTOR_SIZE(exfat->bs);
-	sect = malloc(size);
-	if (!sect)
-		return -ENOMEM;
+	uint16_t flags;
 
-	checksum = 0;
+	flags = le16_to_cpu(exfat->bs->bsx.vol_flags);
+	if (dirty)
+		flags |= 0x02;
+	else
+		flags &= ~0x02;
 
-	boot_calc_checksum((unsigned char *)exfat->bs, size, true, &checksum);
-	for (i = 1; i < 11; i++) {
-		if (exfat_read(exfat->blk_dev->dev_fd, sect, size, i * size) !=
-				(ssize_t)size) {
-			free(sect);
-			return -EIO;
-		}
-		boot_calc_checksum(sect, size, false, &checksum);
+	exfat->bs->bsx.vol_flags = cpu_to_le16(flags);
+	if (exfat_write(exfat->blk_dev->dev_fd, exfat->bs,
+			sizeof(struct pbr), 0) != (ssize_t)sizeof(struct pbr)) {
+		exfat_err("failed to set VolumeDirty\n");
+		return -EIO;
 	}
 
-	if (exfat_read(exfat->blk_dev->dev_fd, sect, size, i * size) !=
-			(ssize_t)size) {
-		free(sect);
+	if (fsync(exfat->blk_dev->dev_fd) != 0) {
+		exfat_err("failed to set VolumeDirty\n");
 		return -EIO;
 	}
-	for (i = 0; i < size/sizeof(checksum); i++) {
-		if (le32_to_cpu(((__le32 *)sect)[i]) != checksum) {
-			union exfat_repair_context rctx = {
-				.bs_checksum.checksum		= checksum,
-				.bs_checksum.checksum_sect	= sect,
-			};
-			if (!exfat_repair(exfat, ER_BS_CHECKSUM, &rctx)) {
-				exfat_err("invalid checksum. 0x%x\n",
-					le32_to_cpu(((__le32 *)sect)[i]));
-				free(sect);
-				return -EIO;
-			}
-		}
-	}
-
-	free(sect);
 	return 0;
 }
 
-static bool exfat_boot_region_check(struct exfat *exfat)
+static int read_boot_region(struct exfat_blk_dev *bd, struct pbr **pbr,
+			    int bs_offset, unsigned int sect_size,
+			    bool verbose)
 {
 	struct pbr *bs;
-	ssize_t ret;
+	int ret = -EINVAL;
 
+	*pbr = NULL;
 	bs = (struct pbr *)malloc(sizeof(struct pbr));
 	if (!bs) {
 		exfat_err("failed to allocate memory\n");
-		return false;
+		return -ENOMEM;
 	}
 
-	exfat->bs = bs;
-
-	ret = exfat_read(exfat->blk_dev->dev_fd, bs, sizeof(*bs), 0);
-	if (ret != sizeof(*bs)) {
-		exfat_err("failed to read a boot sector. %zd\n", ret);
+	if (exfat_read(bd->dev_fd, bs, sizeof(*bs),
+			bs_offset * sect_size) != (ssize_t)sizeof(*bs)) {
+		exfat_err("failed to read a boot sector\n");
+		ret = -EIO;
 		goto err;
 	}
 
 	if (memcmp(bs->bpb.oem_name, "EXFAT   ", 8) != 0) {
-		exfat_err("failed to find exfat file system.\n");
+		if (verbose)
+			exfat_err("failed to find exfat file system\n");
 		goto err;
 	}
 
-	if (EXFAT_SECTOR_SIZE(bs) < 512 || EXFAT_SECTOR_SIZE(bs) > 4 * KB) {
-		exfat_err("too small or big sector size: %d\n",
-				EXFAT_SECTOR_SIZE(bs));
+	ret = boot_region_checksum(bd->dev_fd, bs_offset, sect_size);
+	if (ret < 0)
 		goto err;
-	}
 
-	if (EXFAT_CLUSTER_SIZE(bs) > 32 * MB) {
-		exfat_err("too big cluster size: %d\n", EXFAT_CLUSTER_SIZE(bs));
+	ret = -EINVAL;
+	if (EXFAT_SECTOR_SIZE(bs) < 512 || EXFAT_SECTOR_SIZE(bs) > 4 * KB) {
+		if (verbose)
+			exfat_err("too small or big sector size: %d\n",
+				  EXFAT_SECTOR_SIZE(bs));
 		goto err;
 	}
 
-	ret = boot_region_checksum(exfat);
-	if (ret) {
-		exfat_err("failed to verify the checksum of a boot region. %zd\n",
-			ret);
+	if (EXFAT_CLUSTER_SIZE(bs) > 32 * MB) {
+		if (verbose)
+			exfat_err("too big cluster size: %d\n",
+				  EXFAT_CLUSTER_SIZE(bs));
 		goto err;
 	}
 
 	if (bs->bsx.fs_version[1] != 1 || bs->bsx.fs_version[0] != 0) {
-		exfat_err("unsupported exfat version: %d.%d\n",
-				bs->bsx.fs_version[1], bs->bsx.fs_version[0]);
+		if (verbose)
+			exfat_err("unsupported exfat version: %d.%d\n",
+				  bs->bsx.fs_version[1], bs->bsx.fs_version[0]);
 		goto err;
 	}
 
 	if (bs->bsx.num_fats != 1) {
-		exfat_err("unsupported FAT count: %d\n", bs->bsx.num_fats);
+		if (verbose)
+			exfat_err("unsupported FAT count: %d\n",
+				  bs->bsx.num_fats);
 		goto err;
 	}
 
 	if (le64_to_cpu(bs->bsx.vol_length) * EXFAT_SECTOR_SIZE(bs) >
-			exfat->blk_dev->size) {
-		exfat_err("too large sector count: %" PRIu64 "\n, expected: %llu\n",
-				le64_to_cpu(bs->bsx.vol_length),
-				exfat->blk_dev->num_sectors);
+			bd->size) {
+		if (verbose)
+			exfat_err("too large sector count: %" PRIu64 ", expected: %llu\n",
+				  le64_to_cpu(bs->bsx.vol_length),
+				  bd->num_sectors);
 		goto err;
 	}
 
 	if (le32_to_cpu(bs->bsx.clu_count) * EXFAT_CLUSTER_SIZE(bs) >
-			exfat->blk_dev->size) {
-		exfat_err("too large cluster count: %u, expected: %u\n",
-				le32_to_cpu(bs->bsx.clu_count),
-				exfat->blk_dev->num_clusters);
+			bd->size) {
+		if (verbose)
+			exfat_err("too large cluster count: %u, expected: %u\n",
+				  le32_to_cpu(bs->bsx.clu_count),
+				  bd->num_clusters);
 		goto err;
 	}
 
-	return true;
+	*pbr = bs;
+	return 0;
 err:
 	free(bs);
-	exfat->bs = NULL;
-	return false;
-}
-
-static size_t utf16_len(const __le16 *str, size_t max_size)
-{
-	size_t i = 0;
-
-	while (le16_to_cpu(str[i]) && i < max_size)
-		i++;
-	return i;
-}
-
-/*
- * get references of ancestors that include @child until the count of
- * ancesters is not larger than @count and the count of characters of
- * their names is not larger than @max_char_len.
- * return true if root is reached.
- */
-bool get_ancestors(struct exfat_inode *child,
-		struct exfat_inode **ancestors, int count,
-		int max_char_len,
-		int *ancestor_count)
-{
-	struct exfat_inode *dir;
-	int name_len, char_len;
-	int root_depth, depth, i;
-
-	root_depth = 0;
-	char_len = 0;
-	max_char_len += 1;
-
-	dir = child;
-	while (dir) {
-		name_len = utf16_len(dir->name, NAME_BUFFER_SIZE);
-		if (char_len + name_len > max_char_len)
-			break;
-
-		/* include '/' */
-		char_len += name_len + 1;
-		root_depth++;
-
-		dir = dir->parent;
-	}
-
-	depth = MIN(root_depth, count);
-
-	for (dir = child, i = depth - 1; i >= 0; dir = dir->parent, i--)
-		ancestors[i] = dir;
-
-	*ancestor_count = depth;
-	return dir == NULL;
-}
-
-static int resolve_path(struct path_resolve_ctx *ctx, struct exfat_inode *child)
-{
-	int depth, i;
-	int name_len;
-	__le16 *utf16_path;
-	const __le16 utf16_slash = cpu_to_le16(0x002F);
-	size_t in_size;
-
-	ctx->local_path[0] = '\0';
-
-	get_ancestors(child,
-			ctx->ancestors,
-			sizeof(ctx->ancestors) / sizeof(ctx->ancestors[0]),
-			PATH_MAX,
-			&depth);
-
-	utf16_path = ctx->utf16_path;
-	for (i = 0; i < depth; i++) {
-		name_len = utf16_len(ctx->ancestors[i]->name, NAME_BUFFER_SIZE);
-		memcpy((char *)utf16_path, (char *)ctx->ancestors[i]->name,
-				name_len * 2);
-		utf16_path += name_len;
-		memcpy((char *)utf16_path, &utf16_slash, sizeof(utf16_slash));
-		utf16_path++;
-	}
-
-	if (depth > 0)
-		utf16_path--;
-	in_size = (utf16_path - ctx->utf16_path) * sizeof(__le16);
-	return exfat_utf16_dec(ctx->utf16_path, in_size,
-				ctx->local_path, sizeof(ctx->local_path));
+	return ret;
 }
 
-static int resolve_path_parent(struct path_resolve_ctx *ctx,
-			struct exfat_inode *parent, struct exfat_inode *child)
+static int restore_boot_region(struct exfat_blk_dev *bd, unsigned int sect_size)
 {
+	int i;
+	char *sector;
 	int ret;
-	struct exfat_inode *old;
-
-	old = child->parent;
-	child->parent = parent;
 
-	ret = resolve_path(ctx, child);
-	child->parent = old;
-	return ret;
-}
+	sector = malloc(sect_size);
+	if (!sector)
+		return -ENOMEM;
 
-static int exfat_de_iter_init(struct exfat_de_iter *iter, struct exfat *exfat,
-						struct exfat_inode *dir)
-{
-	ssize_t ret;
-
-	if (!iter->dentries) {
-		iter->read_size = EXFAT_CLUSTER_SIZE(exfat->bs);
-		iter->dentries = malloc(iter->read_size * 2);
-		if (!iter->dentries) {
-			exfat_err("failed to allocate memory\n");
-			return -ENOMEM;
+	for (i = 0; i < 12; i++) {
+		if (exfat_read(bd->dev_fd, sector, sect_size,
+				BACKUP_BOOT_SEC_IDX * sect_size +
+				i * sect_size) !=
+				(ssize_t)sect_size) {
+			ret = -EIO;
+			goto free_sector;
+		}
+		if (i == 0)
+			((struct pbr *)sector)->bsx.perc_in_use = 0xff;
+
+		if (exfat_write(bd->dev_fd, sector, sect_size,
+				BOOT_SEC_IDX * sect_size +
+				i * sect_size) !=
+				(ssize_t)sect_size) {
+			ret = -EIO;
+			goto free_sector;
 		}
 	}
 
-	ret = exfat_file_read(exfat, dir, iter->dentries, iter->read_size, 0);
-	if (ret != iter->read_size) {
-		exfat_err("failed to read directory entries.\n");
-		return -EIO;
+	if (fsync(bd->dev_fd)) {
+		ret = -EIO;
+		goto free_sector;
 	}
+	ret = 0;
 
-	iter->exfat = exfat;
-	iter->parent = dir;
-	iter->de_file_offset = 0;
-	iter->next_read_offset = iter->read_size;
-	iter->max_skip_dentries = 0;
-	return 0;
+free_sector:
+	free(sector);
+	return ret;
 }
 
-static int exfat_de_iter_get(struct exfat_de_iter *iter,
-				int ith, struct exfat_dentry **dentry)
+static int exfat_boot_region_check(struct exfat_blk_dev *blkdev,
+				   struct pbr **bs,
+				   bool ignore_bad_fs_name)
 {
-	off_t de_next_file_offset;
-	unsigned int de_next_offset;
-	bool need_read_1_clus = false;
+	struct pbr *boot_sect;
+	unsigned int sect_size;
 	int ret;
 
-	de_next_file_offset = iter->de_file_offset +
-			ith * sizeof(struct exfat_dentry);
-
-	if (de_next_file_offset + sizeof(struct exfat_dentry) >
-		round_down(iter->parent->size, sizeof(struct exfat_dentry)))
-		return EOF;
-
-	/*
-	 * dentry must be in current cluster, or next cluster which
-	 * will be read
-	 */
-	if (de_next_file_offset -
-		(iter->de_file_offset / iter->read_size) * iter->read_size >=
-		iter->read_size * 2)
-		return -ERANGE;
+	/* First, find out the exfat sector size */
+	boot_sect = malloc(sizeof(*boot_sect));
+	if (boot_sect == NULL)
+		return -ENOMEM;
 
-	de_next_offset = de_next_file_offset % (iter->read_size * 2);
+	if (exfat_read(blkdev->dev_fd, boot_sect,
+		       sizeof(*boot_sect), 0) != (ssize_t)sizeof(*boot_sect)) {
+		exfat_err("failed to read Main boot sector\n");
+		free(boot_sect);
+		return -EIO;
+	}
 
-	/* read a cluster if needed */
-	if (de_next_file_offset >= iter->next_read_offset) {
-		void *buf;
+	if (memcmp(boot_sect->bpb.oem_name, "EXFAT   ", 8) != 0 &&
+	    !ignore_bad_fs_name) {
+		exfat_err("Bad fs_name in boot sector, which does not describe a valid exfat filesystem\n");
+		free(boot_sect);
+		return -ENOTSUP;
+	}
+
+	sect_size = 1 << boot_sect->bsx.sect_size_bits;
+	free(boot_sect);
+
+	/* check boot regions */
+	ret = read_boot_region(blkdev, bs,
+			       BOOT_SEC_IDX, sect_size, true);
+	if (ret == -EINVAL &&
+	    exfat_repair_ask(&exfat_fsck, ER_BS_BOOT_REGION,
+			     "boot region is corrupted. try to restore the region from backup"
+				)) {
+		const unsigned int sector_sizes[] = {512, 4096, 1024, 2048};
+		unsigned int i;
+
+		if (sect_size >= 512 && sect_size <= EXFAT_MAX_SECTOR_SIZE) {
+			ret = read_boot_region(blkdev, bs,
+					       BACKUP_BOOT_SEC_IDX, sect_size,
+					       false);
+			if (!ret)
+				goto restore;
+		}
 
-		need_read_1_clus = de_next_offset < iter->read_size;
-		buf = need_read_1_clus ?
-			iter->dentries : iter->dentries + iter->read_size;
+		for (i = 0; i < sizeof(sector_sizes)/sizeof(sector_sizes[0]); i++) {
+			if (sector_sizes[i] == sect_size)
+				continue;
 
-		ret = exfat_file_read(iter->exfat, iter->parent, buf,
-			iter->read_size, iter->next_read_offset);
-		if (ret == EOF) {
-			return EOF;
-		} else if (ret <= 0) {
-			exfat_err("failed to read a cluster. %d\n", ret);
-			return ret;
+			ret = read_boot_region(blkdev, bs,
+					       BACKUP_BOOT_SEC_IDX,
+					       sector_sizes[i], false);
+			if (!ret) {
+				sect_size = sector_sizes[i];
+				goto restore;
+			}
 		}
-		iter->next_read_offset += iter->read_size;
+		exfat_err("backup boot region is also corrupted\n");
 	}
 
-	if (ith + 1 > iter->max_skip_dentries)
-		iter->max_skip_dentries = ith + 1;
-
-	*dentry = (struct exfat_dentry *) (iter->dentries + de_next_offset);
-	return 0;
+	return ret;
+restore:
+	ret = restore_boot_region(blkdev, sect_size);
+	if (ret) {
+		exfat_err("failed to restore boot region from backup\n");
+		free(*bs);
+		*bs = NULL;
+	}
+	return ret;
 }
 
-/*
- * @skip_dentries must be the largest @ith + 1 of exfat_de_iter_get
- * since the last call of exfat_de_iter_advance
- */
-static int exfat_de_iter_advance(struct exfat_de_iter *iter, int skip_dentries)
+static uint16_t file_calc_checksum(struct exfat_de_iter *iter)
 {
-	if (skip_dentries != iter->max_skip_dentries)
-		return -EINVAL;
+	uint16_t checksum;
+	struct exfat_dentry *file_de, *de;
+	int i;
 
-	iter->max_skip_dentries = 0;
-	iter->de_file_offset = iter->de_file_offset +
-				skip_dentries * sizeof(struct exfat_dentry);
-	return 0;
-}
+	checksum = 0;
+	exfat_de_iter_get(iter, 0, &file_de);
 
-static off_t exfat_de_iter_file_offset(struct exfat_de_iter *iter)
-{
-	return iter->de_file_offset;
+	exfat_calc_dentry_checksum(file_de, &checksum, true);
+	for (i = 1; i <= file_de->file_num_ext; i++) {
+		exfat_de_iter_get(iter, i, &de);
+		exfat_calc_dentry_checksum(de, &checksum, false);
+	}
+	return checksum;
 }
 
-static bool check_inode(struct exfat *exfat, struct exfat_inode *parent,
-						struct exfat_inode *node)
+/*
+ * return 0 if there are no errors, or 1 if errors are fixed, or
+ * an error code
+ */
+static int check_inode(struct exfat_de_iter *iter, struct exfat_inode *node)
 {
-	bool ret = false;
-
-	if (node->size == 0 && node->first_clus != EXFAT_FREE_CLUSTER) {
-		resolve_path_parent(&path_resolve_ctx, parent, node);
-		exfat_err("file is empty, but first cluster is %#x: %s\n",
-				node->first_clus, path_resolve_ctx.local_path);
-		ret = false;
-	}
+	struct exfat *exfat = iter->exfat;
+	struct exfat_dentry *dentry;
+	int ret = 0;
+	uint16_t checksum;
+	bool valid = true;
 
-	if (node->size > 0 && exfat_invalid_clus(exfat, node->first_clus)) {
-		resolve_path_parent(&path_resolve_ctx, parent, node);
-		exfat_err("first cluster %#x is invalid: %s\n",
-				node->first_clus, path_resolve_ctx.local_path);
-		ret = false;
-	}
+	ret = check_clus_chain(iter, node);
+	if (ret < 0)
+		return ret;
 
 	if (node->size > le32_to_cpu(exfat->bs->bsx.clu_count) *
-				EXFAT_CLUSTER_SIZE(exfat->bs)) {
-		resolve_path_parent(&path_resolve_ctx, parent, node);
-		exfat_err("size %" PRIu64 " is greater than cluster heap: %s\n",
-				node->size, path_resolve_ctx.local_path);
-		ret = false;
+				(uint64_t)exfat->clus_size) {
+		fsck_err(iter->parent, node,
+			"size %" PRIu64 " is greater than cluster heap\n",
+			node->size);
+		valid = false;
 	}
 
 	if (node->size == 0 && node->is_contiguous) {
-		resolve_path_parent(&path_resolve_ctx, parent, node);
-		exfat_err("empty, but marked as contiguous: %s\n",
-					path_resolve_ctx.local_path);
-		ret = false;
+		if (repair_file_ask(iter, node, ER_FILE_ZERO_NOFAT,
+				"empty, but has no Fat chain")) {
+			exfat_de_iter_get_dirty(iter, 1, &dentry);
+			dentry->stream_flags &= ~EXFAT_SF_CONTIGUOUS;
+			ret = 1;
+		} else
+			valid = false;
 	}
 
 	if ((node->attr & ATTR_SUBDIR) &&
-			node->size % EXFAT_CLUSTER_SIZE(exfat->bs) != 0) {
-		resolve_path_parent(&path_resolve_ctx, parent, node);
-		exfat_err("directory size %" PRIu64 " is not divisible by %d: %s\n",
-				node->size, EXFAT_CLUSTER_SIZE(exfat->bs),
-				path_resolve_ctx.local_path);
-		ret = false;
+			node->size % exfat->clus_size != 0) {
+		fsck_err(iter->parent, node,
+			"directory size %" PRIu64 " is not divisible by %d\n",
+			node->size, exfat->clus_size);
+		valid = false;
 	}
 
-	if (!node->is_contiguous && !inode_check_clus_chain(exfat, node)) {
-		resolve_path_parent(&path_resolve_ctx, parent, node);
-		exfat_err("corrupted cluster chain: %s\n",
-				path_resolve_ctx.local_path);
-		ret = false;
+	checksum = file_calc_checksum(iter);
+	exfat_de_iter_get(iter, 0, &dentry);
+	if (checksum != le16_to_cpu(dentry->file_checksum)) {
+		exfat_de_iter_get_dirty(iter, 0, &dentry);
+		dentry->file_checksum = cpu_to_le16(checksum);
+		ret = 1;
 	}
 
-	return ret;
+	return valid ? ret : -EINVAL;
 }
 
-static void dentry_calc_checksum(struct exfat_dentry *dentry,
-				__le16 *checksum, bool primary)
+static int handle_duplicated_filename(struct exfat_de_iter *iter,
+		struct exfat_inode *inode)
 {
-	unsigned int i;
-	uint8_t *bytes;
+	int ret;
+	struct exfat_lookup_filter filter;
+	char filename[PATH_MAX + 1] = {0};
 
-	bytes = (uint8_t *)dentry;
+	ret = exfat_lookup_file_by_utf16name(iter->exfat, iter->parent,
+			inode->name, &filter);
+	if (ret)
+		return ret;
+
+	free(filter.out.dentry_set);
 
-	*checksum = ((*checksum << 15) | (*checksum >> 1)) + bytes[0];
-	*checksum = ((*checksum << 15) | (*checksum >> 1)) + bytes[1];
+	/* Hash is same, but filename is not same */
+	if (exfat_de_iter_device_offset(iter) == filter.out.dev_offset)
+		return 0;
 
-	i = primary ? 4 : 2;
-	for (; i < sizeof(*dentry); i++) {
-		*checksum = ((*checksum << 15) | (*checksum >> 1)) + bytes[i];
+	ret = exfat_utf16_dec(inode->name, NAME_BUFFER_SIZE, filename,
+			PATH_MAX);
+	if (ret < 0) {
+		exfat_err("failed to decode filename\n");
+		return ret;
 	}
+
+	return exfat_repair_rename_ask(&exfat_fsck, iter, filename,
+			ER_DE_DUPLICATED_NAME, "filename is duplicated");
 }
 
-static __le16 file_calc_checksum(struct exfat_de_iter *iter)
+static int check_name_dentry_set(struct exfat_de_iter *iter,
+				 struct exfat_inode *inode)
 {
-	__le16 checksum;
-	struct exfat_dentry *file_de, *de;
-	int i;
-
-	checksum = 0;
-	exfat_de_iter_get(iter, 0, &file_de);
+	struct exfat_dentry *stream_de;
+	size_t name_len;
+	__u16 hash;
+
+	exfat_de_iter_get(iter, 1, &stream_de);
+
+	name_len = exfat_utf16_len(inode->name, NAME_BUFFER_SIZE);
+	if (stream_de->stream_name_len != name_len) {
+		if (repair_file_ask(iter, NULL, ER_DE_NAME_LEN,
+				    "the name length of a file is wrong")) {
+			exfat_de_iter_get_dirty(iter, 1, &stream_de);
+			stream_de->stream_name_len = (__u8)name_len;
+		} else {
+			return -EINVAL;
+		}
+	}
 
-	dentry_calc_checksum(file_de, &checksum, true);
-	for (i = 1; i <= file_de->file_num_ext; i++) {
-		exfat_de_iter_get(iter, i, &de);
-		dentry_calc_checksum(de, &checksum, false);
+	hash = exfat_calc_name_hash(iter->exfat, inode->name, (int)name_len);
+	if (cpu_to_le16(hash) != stream_de->stream_name_hash) {
+		if (repair_file_ask(iter, NULL, ER_DE_NAME_HASH,
+				    "the name hash of a file is wrong")) {
+			exfat_de_iter_get_dirty(iter, 1, &stream_de);
+			stream_de->stream_name_hash = cpu_to_le16(hash);
+		} else {
+			return -EINVAL;
+		}
 	}
 
-	return checksum;
+	if (BITMAP_GET(iter->name_hash_bitmap, hash)) {
+		int ret = handle_duplicated_filename(iter, inode);
+
+		if (ret)
+			return ret;
+	} else
+		BITMAP_SET(iter->name_hash_bitmap, hash);
+
+	return 0;
 }
 
-static int read_file_dentries(struct exfat_de_iter *iter,
-			struct exfat_inode **new_node, int *skip_dentries)
+const __le16 MSDOS_DOT[ENTRY_NAME_MAX] = {cpu_to_le16(46), 0, };
+const __le16 MSDOS_DOTDOT[ENTRY_NAME_MAX] = {cpu_to_le16(46), cpu_to_le16(46), 0, };
+
+static int handle_dot_dotdot_filename(struct exfat_de_iter *iter,
+				      struct exfat_dentry *dentry,
+				      int strm_name_len)
 {
-	struct exfat_dentry *file_de, *stream_de, *name_de;
-	struct exfat_inode *node;
-	int i, ret;
-	__le16 checksum;
+	char *filename;
+
+	if (!memcmp(dentry->name_unicode, MSDOS_DOT, strm_name_len * 2))
+		filename = ".";
+	else if (!memcmp(dentry->name_unicode, MSDOS_DOTDOT,
+			 strm_name_len * 2))
+		filename = "..";
+	else
+		return 0;
 
-	/* TODO: mtime, atime, ... */
+	return exfat_repair_rename_ask(&exfat_fsck, iter, filename,
+			ER_DE_DOT_NAME, "filename is not allowed");
+}
+
+static int read_file_dentry_set(struct exfat_de_iter *iter,
+				struct exfat_inode **new_node, int *skip_dentries)
+{
+	struct exfat_dentry *file_de, *stream_de, *dentry;
+	struct exfat_inode *node = NULL;
+	int i, ret;
+	bool need_delete = false;
+	uint16_t checksum;
 
 	ret = exfat_de_iter_get(iter, 0, &file_de);
 	if (ret || file_de->type != EXFAT_FILE) {
-		exfat_err("failed to get file dentry. %d\n", ret);
+		exfat_err("failed to get file dentry\n");
 		return -EINVAL;
 	}
+
+	checksum = file_calc_checksum(iter);
+	if (checksum != le16_to_cpu(file_de->file_checksum)) {
+		if (repair_file_ask(iter, NULL, ER_DE_CHECKSUM,
+				    "the checksum of a file is wrong"))
+			need_delete = true;
+		*skip_dentries = 1;
+		goto skip_dset;
+	}
+
+	if (file_de->file_num_ext < 2) {
+		if (repair_file_ask(iter, NULL, ER_DE_SECONDARY_COUNT,
+				    "a file has too few secondary count. %d",
+				    file_de->file_num_ext))
+			need_delete = true;
+		*skip_dentries = 1;
+		goto skip_dset;
+	}
+
 	ret = exfat_de_iter_get(iter, 1, &stream_de);
 	if (ret || stream_de->type != EXFAT_STREAM) {
-		exfat_err("failed to get stream dentry. %d\n", ret);
-		return -EINVAL;
+		if (repair_file_ask(iter, NULL, ER_DE_STREAM,
+				    "failed to get stream dentry"))
+			need_delete = true;
+		*skip_dentries = 2;
+		goto skip_dset;
 	}
 
 	*new_node = NULL;
-	node = alloc_exfat_inode(le16_to_cpu(file_de->file_attr));
+	node = exfat_alloc_inode(le16_to_cpu(file_de->file_attr));
 	if (!node)
 		return -ENOMEM;
 
-	if (file_de->file_num_ext < 2) {
-		exfat_err("too few secondary count. %d\n",
-				file_de->file_num_ext);
-		free_exfat_inode(node);
-		return -EINVAL;
-	}
-
-	for (i = 2; i <= file_de->file_num_ext; i++) {
-		ret = exfat_de_iter_get(iter, i, &name_de);
-		if (ret || name_de->type != EXFAT_NAME) {
-			exfat_err("failed to get name dentry. %d\n", ret);
-			ret = -EINVAL;
-			goto err;
+	for (i = 2; i <= MIN(file_de->file_num_ext, 1 + MAX_NAME_DENTRIES); i++) {
+		ret = exfat_de_iter_get(iter, i, &dentry);
+		if (ret || dentry->type != EXFAT_NAME) {
+			if (i > 2 && repair_file_ask(iter, NULL, ER_DE_NAME,
+						     "failed to get name dentry")) {
+				exfat_de_iter_get_dirty(iter, 0, &file_de);
+				file_de->file_num_ext = i - 1;
+				break;
+			}
+			*skip_dentries = i + 1;
+			goto skip_dset;
 		}
 
 		memcpy(node->name +
-			(i-2) * ENTRY_NAME_MAX, name_de->name_unicode,
-			sizeof(name_de->name_unicode));
+		       (i - 2) * ENTRY_NAME_MAX, dentry->name_unicode,
+		       sizeof(dentry->name_unicode));
 	}
 
-	checksum = file_calc_checksum(iter);
-	if (le16_to_cpu(file_de->file_checksum) != checksum) {
-		exfat_err("invalid checksum. 0x%x != 0x%x\n",
-			le16_to_cpu(file_de->file_checksum),
-			le16_to_cpu(checksum));
-		ret = -EINVAL;
-		goto err;
+	ret = check_name_dentry_set(iter, node);
+	if (ret) {
+		*skip_dentries = file_de->file_num_ext + 1;
+		goto skip_dset;
+	}
+
+	if (file_de->file_num_ext == 2 && stream_de->stream_name_len <= 2) {
+		ret = handle_dot_dotdot_filename(iter, dentry,
+				stream_de->stream_name_len);
+		if (ret < 0) {
+			*skip_dentries = file_de->file_num_ext + 1;
+			goto skip_dset;
+		}
 	}
 
-	node->size = le64_to_cpu(stream_de->stream_size);
 	node->first_clus = le32_to_cpu(stream_de->stream_start_clu);
 	node->is_contiguous =
 		((stream_de->stream_flags & EXFAT_SF_CONTIGUOUS) != 0);
+	node->size = le64_to_cpu(stream_de->stream_size);
 
-	if (le64_to_cpu(stream_de->stream_valid_size) > node->size) {
-		resolve_path_parent(&path_resolve_ctx, iter->parent, node);
-		exfat_err("valid size %" PRIu64 " greater than size %" PRIu64 ": %s\n",
-			le64_to_cpu(stream_de->stream_valid_size), node->size,
-			path_resolve_ctx.local_path);
-		ret = -EINVAL;
-		goto err;
+	if (node->size < le64_to_cpu(stream_de->stream_valid_size)) {
+		*skip_dentries = file_de->file_num_ext + 1;
+		if (repair_file_ask(iter, node, ER_FILE_VALID_SIZE,
+				    "valid size %" PRIu64 " greater than size %" PRIu64,
+				    le64_to_cpu(stream_de->stream_valid_size),
+				    node->size)) {
+			exfat_de_iter_get_dirty(iter, 1, &stream_de);
+			stream_de->stream_valid_size =
+					stream_de->stream_size;
+		} else {
+			*skip_dentries = file_de->file_num_ext + 1;
+			goto skip_dset;
+		}
 	}
 
 	*skip_dentries = (file_de->file_num_ext + 1);
 	*new_node = node;
 	return 0;
-err:
-	*skip_dentries = 0;
+skip_dset:
+	if (need_delete) {
+		exfat_de_iter_get_dirty(iter, 0, &dentry);
+		dentry->type &= EXFAT_DELETE;
+	}
+	for (i = 1; i < *skip_dentries; i++) {
+		exfat_de_iter_get(iter, i, &dentry);
+		if (dentry->type == EXFAT_FILE)
+			break;
+		if (need_delete) {
+			exfat_de_iter_get_dirty(iter, i, &dentry);
+			dentry->type &= EXFAT_DELETE;
+		}
+	}
+	*skip_dentries = i;
 	*new_node = NULL;
-	free_exfat_inode(node);
-	return ret;
+	exfat_free_inode(node);
+	return need_delete ? 1 : -EINVAL;
 }
 
 static int read_file(struct exfat_de_iter *de_iter,
@@ -875,120 +858,124 @@ static int read_file(struct exfat_de_iter *de_iter,
 
 	*new_node = NULL;
 
-	ret = read_file_dentries(de_iter, &node, dentry_count);
-	if (ret) {
-		exfat_err("corrupted file directory entries.\n");
+	ret = read_file_dentry_set(de_iter, &node, dentry_count);
+	if (ret)
 		return ret;
-	}
 
-	ret = check_inode(de_iter->exfat, de_iter->parent, node);
-	if (ret) {
-		exfat_err("corrupted file directory entries.\n");
-		free_exfat_inode(node);
-		return ret;
+	ret = check_inode(de_iter, node);
+	if (ret < 0) {
+		exfat_free_inode(node);
+		return -EINVAL;
 	}
 
-	node->dentry_file_offset = exfat_de_iter_file_offset(de_iter);
+	if (node->attr & ATTR_SUBDIR)
+		exfat_stat.dir_count++;
+	else
+		exfat_stat.file_count++;
 	*new_node = node;
-	return 0;
-}
-
-static bool read_volume_label(struct exfat_de_iter *iter)
-{
-	struct exfat *exfat;
-	struct exfat_dentry *dentry;
-	__le16 disk_label[VOLUME_LABEL_MAX_LEN];
-
-	exfat = iter->exfat;
-	if (exfat_de_iter_get(iter, 0, &dentry))
-		return false;
-
-	if (dentry->vol_char_cnt == 0)
-		return true;
-
-	if (dentry->vol_char_cnt > VOLUME_LABEL_MAX_LEN) {
-		exfat_err("too long label. %d\n", dentry->vol_char_cnt);
-		return false;
-	}
-
-	memcpy(disk_label, dentry->vol_label, sizeof(disk_label));
-	if (exfat_utf16_dec(disk_label, dentry->vol_char_cnt*2,
-		exfat->volume_label, sizeof(exfat->volume_label)) < 0) {
-		exfat_err("failed to decode volume label\n");
-		return false;
-	}
-
-	exfat_info("volume label [%s]\n", exfat->volume_label);
-	return true;
+	return ret;
 }
 
-static bool read_alloc_bitmap(struct exfat_de_iter *iter)
+static int read_bitmap(struct exfat *exfat)
 {
+	struct exfat_lookup_filter filter = {
+		.in.type	= EXFAT_BITMAP,
+		.in.dentry_count = 0,
+		.in.filter	= NULL,
+		.in.param	= NULL,
+	};
 	struct exfat_dentry *dentry;
-	struct exfat *exfat;
-	ssize_t alloc_bitmap_size;
+	int retval;
 
-	exfat = iter->exfat;
-	if (exfat_de_iter_get(iter, 0, &dentry))
-		return false;
+	retval = exfat_lookup_dentry_set(exfat, exfat->root, &filter);
+	if (retval)
+		return retval;
 
+	dentry = filter.out.dentry_set;
 	exfat_debug("start cluster %#x, size %#" PRIx64 "\n",
 			le32_to_cpu(dentry->bitmap_start_clu),
 			le64_to_cpu(dentry->bitmap_size));
 
-	exfat->bit_count = le32_to_cpu(exfat->bs->bsx.clu_count);
-
 	if (le64_to_cpu(dentry->bitmap_size) <
-			DIV_ROUND_UP(exfat->bit_count, 8)) {
+			DIV_ROUND_UP(exfat->clus_count, 8)) {
 		exfat_err("invalid size of allocation bitmap. 0x%" PRIx64 "\n",
 				le64_to_cpu(dentry->bitmap_size));
-		return false;
+		return -EINVAL;
 	}
-	if (exfat_invalid_clus(exfat, le32_to_cpu(dentry->bitmap_start_clu))) {
+	if (!exfat_heap_clus(exfat, le32_to_cpu(dentry->bitmap_start_clu))) {
 		exfat_err("invalid start cluster of allocate bitmap. 0x%x\n",
 				le32_to_cpu(dentry->bitmap_start_clu));
-		return false;
+		return -EINVAL;
 	}
 
-	/* TODO: bitmap could be very large. */
-	alloc_bitmap_size = EXFAT_BITMAP_SIZE(exfat->bit_count);
-	exfat->alloc_bitmap = (__u32 *)malloc(alloc_bitmap_size);
-	if (!exfat->alloc_bitmap) {
-		exfat_err("failed to allocate bitmap\n");
-		return false;
-	}
+	exfat->disk_bitmap_clus = le32_to_cpu(dentry->bitmap_start_clu);
+	exfat->disk_bitmap_size = DIV_ROUND_UP(exfat->clus_count, 8);
 
-	if (exfat_read(exfat->blk_dev->dev_fd,
-			exfat->alloc_bitmap, alloc_bitmap_size,
-			exfat_c2o(exfat,
-			le32_to_cpu(dentry->bitmap_start_clu))) !=
-			alloc_bitmap_size) {
-		exfat_err("failed to read bitmap\n");
-		free(exfat->alloc_bitmap);
-		exfat->alloc_bitmap = NULL;
-		return false;
-	}
+	exfat_bitmap_set_range(exfat, exfat->alloc_bitmap,
+			       le64_to_cpu(dentry->bitmap_start_clu),
+			       DIV_ROUND_UP(exfat->disk_bitmap_size,
+					    exfat->clus_size));
+	free(filter.out.dentry_set);
 
-	return true;
+	if (exfat_read(exfat->blk_dev->dev_fd, exfat->disk_bitmap,
+			exfat->disk_bitmap_size,
+			exfat_c2o(exfat, exfat->disk_bitmap_clus)) !=
+			(ssize_t)exfat->disk_bitmap_size)
+		return -EIO;
+	return 0;
 }
 
-static bool read_upcase_table(struct exfat_de_iter *iter)
+static int decompress_upcase_table(const __le16 *in_table, size_t in_len,
+				   __u16 *out_table, size_t out_len)
 {
-	struct exfat_dentry *dentry;
-	struct exfat *exfat;
+	size_t i, k;
+	uint16_t ch;
+
+	if (in_len > out_len)
+		return -E2BIG;
+
+	for (k = 0; k < out_len; k++)
+		out_table[k] = k;
+
+	for (i = 0, k = 0; i < in_len && k < out_len; i++) {
+		ch = le16_to_cpu(in_table[i]);
+
+		if (ch == 0xFFFF && i + 1 < in_len) {
+			uint16_t len = le16_to_cpu(in_table[++i]);
+
+			k += len;
+		} else {
+			out_table[k++] = ch;
+		}
+	}
+	return 0;
+}
+
+static int read_upcase_table(struct exfat *exfat)
+{
+	struct exfat_lookup_filter filter = {
+		.in.type	= EXFAT_UPCASE,
+		.in.dentry_count = 0,
+		.in.filter	= NULL,
+		.in.param	= NULL,
+	};
+	struct exfat_dentry *dentry = NULL;
+	__le16 *upcase = NULL;
+	int retval;
 	ssize_t size;
-	__le16 *upcase;
 	__le32 checksum;
 
-	exfat = iter->exfat;
+	retval = exfat_lookup_dentry_set(exfat, exfat->root, &filter);
+	if (retval)
+		return retval;
 
-	if (exfat_de_iter_get(iter, 0, &dentry))
-		return false;
+	dentry = filter.out.dentry_set;
 
-	if (exfat_invalid_clus(exfat, le32_to_cpu(dentry->upcase_start_clu))) {
+	if (!exfat_heap_clus(exfat, le32_to_cpu(dentry->upcase_start_clu))) {
 		exfat_err("invalid start cluster of upcase table. 0x%x\n",
 			le32_to_cpu(dentry->upcase_start_clu));
-		return false;
+		retval = -EINVAL;
+		goto out;
 	}
 
 	size = (ssize_t)le64_to_cpu(dentry->upcase_size);
@@ -996,21 +983,23 @@ static bool read_upcase_table(struct exfat_de_iter *iter)
 			size == 0 || size % sizeof(__le16)) {
 		exfat_err("invalid size of upcase table. 0x%" PRIx64 "\n",
 			le64_to_cpu(dentry->upcase_size));
-		return false;
+		retval = -EINVAL;
+		goto out;
 	}
 
 	upcase = (__le16 *)malloc(size);
 	if (!upcase) {
 		exfat_err("failed to allocate upcase table\n");
-		return false;
+		retval = -ENOMEM;
+		goto out;
 	}
 
 	if (exfat_read(exfat->blk_dev->dev_fd, upcase, size,
 			exfat_c2o(exfat,
 			le32_to_cpu(dentry->upcase_start_clu))) != size) {
 		exfat_err("failed to read upcase table\n");
-		free(upcase);
-		return false;
+		retval = -EIO;
+		goto out;
 	}
 
 	checksum = 0;
@@ -1018,38 +1007,59 @@ static bool read_upcase_table(struct exfat_de_iter *iter)
 	if (le32_to_cpu(dentry->upcase_checksum) != checksum) {
 		exfat_err("corrupted upcase table %#x (expected: %#x)\n",
 			checksum, le32_to_cpu(dentry->upcase_checksum));
-		free(upcase);
-		return false;
+		retval = -EINVAL;
+		goto out;
 	}
 
-	free(upcase);
-	return true;
+	exfat_bitmap_set_range(exfat, exfat->alloc_bitmap,
+			       le32_to_cpu(dentry->upcase_start_clu),
+			       DIV_ROUND_UP(le64_to_cpu(dentry->upcase_size),
+					    exfat->clus_size));
+
+	exfat->upcase_table = calloc(1,
+				     sizeof(uint16_t) * EXFAT_UPCASE_TABLE_CHARS);
+	if (!exfat->upcase_table) {
+		retval = -EIO;
+		goto out;
+	}
+
+	decompress_upcase_table(upcase, size / 2,
+				exfat->upcase_table, EXFAT_UPCASE_TABLE_CHARS);
+out:
+	if (dentry)
+		free(dentry);
+	if (upcase)
+		free(upcase);
+	return retval;
 }
 
-static int read_children(struct exfat *exfat, struct exfat_inode *dir)
+static int read_children(struct exfat_fsck *fsck, struct exfat_inode *dir)
 {
-	int ret;
+	struct exfat *exfat = fsck->exfat;
 	struct exfat_inode *node = NULL;
 	struct exfat_dentry *dentry;
-	int dentry_count;
-	struct list_head sub_dir_list;
 	struct exfat_de_iter *de_iter;
+	int dentry_count;
+	int ret;
 
-	INIT_LIST_HEAD(&sub_dir_list);
-
-	de_iter = &exfat->de_iter;
-	ret = exfat_de_iter_init(de_iter, exfat, dir);
+	de_iter = &fsck->de_iter;
+	ret = exfat_de_iter_init(de_iter, exfat, dir, fsck->buffer_desc);
 	if (ret == EOF)
 		return 0;
 	else if (ret)
 		return ret;
 
+	de_iter->name_hash_bitmap = fsck->name_hash_bitmap;
+	memset(fsck->name_hash_bitmap, 0,
+			EXFAT_BITMAP_SIZE(EXFAT_MAX_HASH_COUNT));
+
 	while (1) {
 		ret = exfat_de_iter_get(de_iter, 0, &dentry);
 		if (ret == EOF) {
 			break;
 		} else if (ret) {
-			exfat_err("failed to get a dentry. %d\n", ret);
+			fsck_err(dir->parent, dir,
+				"failed to get a dentry. %d\n", ret);
 			goto err;
 		}
 
@@ -1058,60 +1068,103 @@ static int read_children(struct exfat *exfat, struct exfat_inode *dir)
 		switch (dentry->type) {
 		case EXFAT_FILE:
 			ret = read_file(de_iter, &node, &dentry_count);
-			if (ret) {
-				exfat_err("failed to verify file. %d\n", ret);
-				goto err;
+			if (ret < 0) {
+				exfat_stat.error_count++;
+				break;
+			} else if (ret) {
+				exfat_stat.error_count++;
+				exfat_stat.fixed_count++;
 			}
 
-			if ((node->attr & ATTR_SUBDIR) && node->size) {
-				node->parent = dir;
-				list_add_tail(&node->sibling, &dir->children);
-				list_add_tail(&node->list, &sub_dir_list);
-			} else
-				free_exfat_inode(node);
-			break;
-		case EXFAT_VOLUME:
-			if (!read_volume_label(de_iter)) {
-				exfat_err("failed to verify volume label\n");
-				ret = -EINVAL;
-				goto err;
+			if (node) {
+				if ((node->attr & ATTR_SUBDIR) && node->size) {
+					node->parent = dir;
+					list_add_tail(&node->sibling,
+						      &dir->children);
+					list_add_tail(&node->list,
+						      &exfat->dir_list);
+				} else {
+					exfat_free_inode(node);
+				}
 			}
 			break;
+		case EXFAT_LAST:
+			goto out;
+		case EXFAT_VOLUME:
 		case EXFAT_BITMAP:
-			if (!read_alloc_bitmap(de_iter)) {
-				exfat_err(
-					"failed to verify allocation bitmap\n");
-				ret = -EINVAL;
-				goto err;
-			}
-			break;
 		case EXFAT_UPCASE:
-			if (!read_upcase_table(de_iter)) {
-				exfat_err(
-					"failed to verify upcase table\n");
-				ret = -EINVAL;
-				goto err;
-			}
-			break;
+		case EXFAT_GUID:
+			if (dir == exfat->root)
+				break;
+			/* fallthrough */
 		default:
-			if (IS_EXFAT_DELETED(dentry->type) ||
-					(dentry->type == EXFAT_UNUSED))
+			if (IS_EXFAT_DELETED(dentry->type))
 				break;
-			exfat_err("unknown entry type. 0x%x\n", dentry->type);
-			ret = -EINVAL;
-			goto err;
+			if (repair_file_ask(de_iter, NULL, ER_DE_UNKNOWN,
+					    "unknown entry type %#x at %07" PRIx64,
+					    dentry->type,
+					    exfat_de_iter_file_offset(de_iter))) {
+				struct exfat_dentry *dentry;
+
+				exfat_de_iter_get_dirty(de_iter, 0, &dentry);
+				dentry->type &= EXFAT_DELETE;
+			}
+			break;
 		}
 
 		exfat_de_iter_advance(de_iter, dentry_count);
 	}
-	list_splice(&sub_dir_list, &exfat->dir_list);
+out:
+	exfat_de_iter_flush(de_iter);
 	return 0;
 err:
-	inode_free_children(dir, false);
+	exfat_free_children(dir, false);
 	INIT_LIST_HEAD(&dir->children);
+	exfat_de_iter_flush(de_iter);
 	return ret;
 }
 
+/* write bitmap segments for clusters which are marked
+ * as free, but allocated to files.
+ */
+static int write_bitmap(struct exfat_fsck *fsck)
+{
+	struct exfat *exfat = fsck->exfat;
+	bitmap_t *disk_b, *alloc_b, *ohead_b;
+	off_t dev_offset;
+	unsigned int i, bitmap_bytes, byte_offset, write_bytes;
+
+	dev_offset = exfat_c2o(exfat, exfat->disk_bitmap_clus);
+	bitmap_bytes = EXFAT_BITMAP_SIZE(le32_to_cpu(exfat->bs->bsx.clu_count));
+
+	disk_b = (bitmap_t *)exfat->disk_bitmap;
+	alloc_b = (bitmap_t *)exfat->alloc_bitmap;
+	ohead_b = (bitmap_t *)exfat->ohead_bitmap;
+
+	for (i = 0; i < bitmap_bytes / sizeof(bitmap_t); i++)
+		ohead_b[i] = alloc_b[i] | disk_b[i];
+
+	i = 0;
+	while (i < bitmap_bytes / sizeof(bitmap_t)) {
+		if (ohead_b[i] == disk_b[i]) {
+			i++;
+			continue;
+		}
+
+		byte_offset = ((i * sizeof(bitmap_t)) / 512) * 512;
+		write_bytes = MIN(512, bitmap_bytes - byte_offset);
+
+		if (exfat_write(exfat->blk_dev->dev_fd,
+				(char *)ohead_b + byte_offset, write_bytes,
+				dev_offset + byte_offset) != (ssize_t)write_bytes)
+			return -EIO;
+
+		i = (byte_offset + write_bytes) / sizeof(bitmap_t);
+	}
+	return 0;
+
+}
+
 /*
  * for each directory in @dir_list.
  * 1. read all dentries and allocate exfat_nodes for files and directories.
@@ -1119,105 +1172,289 @@ err:
  * 2. free all of file exfat_nodes.
  * 3. if the directory does not have children, free its exfat_node.
  */
-static bool exfat_filesystem_check(struct exfat *exfat)
+static int exfat_filesystem_check(struct exfat_fsck *fsck)
 {
+	struct exfat *exfat = fsck->exfat;
 	struct exfat_inode *dir;
-	bool ret = true;
+	int ret = 0, dir_errors;
 
 	if (!exfat->root) {
 		exfat_err("root is NULL\n");
-		return false;
+		return -ENOENT;
+	}
+
+	fsck->name_hash_bitmap = malloc(EXFAT_BITMAP_SIZE(EXFAT_MAX_HASH_COUNT));
+	if (!fsck->name_hash_bitmap) {
+		exfat_err("failed to allocate name hash bitmap\n");
+		return -ENOMEM;
 	}
 
 	list_add(&exfat->root->list, &exfat->dir_list);
 
 	while (!list_empty(&exfat->dir_list)) {
-		dir = list_entry(exfat->dir_list.next, struct exfat_inode, list);
+		dir = list_entry(exfat->dir_list.next,
+				 struct exfat_inode, list);
 
 		if (!(dir->attr & ATTR_SUBDIR)) {
-			resolve_path(&path_resolve_ctx, dir);
-			ret = false;
-			exfat_err("failed to travel directories. "
-					"the node is not directory: %s\n",
-					path_resolve_ctx.local_path);
+			fsck_err(dir->parent, dir,
+				"failed to travel directories. "
+				"the node is not directory\n");
+			ret = -EINVAL;
 			goto out;
 		}
 
-		if (read_children(exfat, dir)) {
-			resolve_path(&path_resolve_ctx, dir);
-			ret = false;
-			exfat_err("failed to check dentries: %s\n",
+		dir_errors = read_children(fsck, dir);
+		if (dir_errors) {
+			exfat_resolve_path(&path_resolve_ctx, dir);
+			exfat_debug("failed to check dentries: %s\n",
 					path_resolve_ctx.local_path);
-			goto out;
+			ret = dir_errors;
 		}
 
 		list_del(&dir->list);
-		inode_free_file_children(dir);
-		inode_free_ancestors(dir);
+		exfat_free_file_children(dir);
+		exfat_free_ancestors(dir);
 	}
 out:
 	exfat_free_dir_list(exfat);
-	exfat->root = NULL;
+	free(fsck->name_hash_bitmap);
 	return ret;
 }
 
-static bool exfat_root_dir_check(struct exfat *exfat)
+static int exfat_root_dir_check(struct exfat *exfat)
 {
 	struct exfat_inode *root;
-	clus_t clus_count;
+	clus_t clus_count = 0;
+	int err;
 
-	root = alloc_exfat_inode(ATTR_SUBDIR);
-	if (!root) {
-		exfat_err("failed to allocate memory\n");
-		return false;
-	}
+	root = exfat_alloc_inode(ATTR_SUBDIR);
+	if (!root)
+		return -ENOMEM;
 
+	exfat->root = root;
 	root->first_clus = le32_to_cpu(exfat->bs->bsx.root_cluster);
-	if (!inode_get_clus_count(exfat, root, &clus_count)) {
+	if (root_check_clus_chain(exfat, root, &clus_count)) {
 		exfat_err("failed to follow the cluster chain of root\n");
-		goto err;
+		exfat_free_inode(root);
+		exfat->root = NULL;
+		return -EINVAL;
 	}
-	root->size = clus_count * EXFAT_CLUSTER_SIZE(exfat->bs);
+	root->size = clus_count * exfat->clus_size;
 
-	exfat->root = root;
+	exfat_stat.dir_count++;
 	exfat_debug("root directory: start cluster[0x%x] size[0x%" PRIx64 "]\n",
 		root->first_clus, root->size);
-	return true;
-err:
-	free_exfat_inode(root);
-	exfat->root = NULL;
-	return false;
+
+	err = exfat_read_volume_label(exfat);
+	if (err && err != EOF)
+		exfat_err("failed to read volume label\n");
+	err = 0;
+
+	err = read_bitmap(exfat);
+	if (err) {
+		exfat_err("failed to read bitmap\n");
+		return -EINVAL;
+	}
+
+	err = read_upcase_table(exfat);
+	if (err) {
+		exfat_err("failed to read upcase table\n");
+		return -EINVAL;
+	}
+
+	root->dev_offset = 0;
+	err = exfat_build_file_dentry_set(exfat, " ", ATTR_SUBDIR,
+					  &root->dentry_set, &root->dentry_count);
+	if (err) {
+		exfat_free_inode(root);
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static int read_lostfound(struct exfat *exfat, struct exfat_inode **lostfound)
+{
+	struct exfat_lookup_filter filter;
+	struct exfat_inode *inode;
+	int err;
+
+	err = exfat_lookup_file(exfat, exfat->root, "LOST+FOUND", &filter);
+	if (err)
+		return err;
+
+	inode = exfat_alloc_inode(ATTR_SUBDIR);
+	if (!inode) {
+		free(filter.out.dentry_set);
+		return -ENOMEM;
+	}
+
+	inode->dentry_set = filter.out.dentry_set;
+	inode->dentry_count = filter.out.dentry_count;
+	inode->dev_offset = filter.out.dev_offset;
+
+	inode->first_clus =
+		le32_to_cpu(filter.out.dentry_set[1].dentry.stream.start_clu);
+	inode->size =
+		le64_to_cpu(filter.out.dentry_set[1].dentry.stream.size);
+
+	*lostfound = inode;
+	return 0;
 }
 
-void exfat_show_info(struct exfat *exfat)
+/* Create temporary files under LOST+FOUND and assign orphan
+ * chains of clusters to these files.
+ */
+static int rescue_orphan_clusters(struct exfat_fsck *fsck)
 {
-	exfat_info("Bytes per sector: %d\n",
-			1 << exfat->bs->bsx.sect_size_bits);
-	exfat_info("Sectors per cluster: %d\n",
-			1 << exfat->bs->bsx.sect_per_clus_bits);
-	exfat_info("Cluster heap count: %d(0x%x)\n",
-			le32_to_cpu(exfat->bs->bsx.clu_count),
-			le32_to_cpu(exfat->bs->bsx.clu_count));
-	exfat_info("Cluster heap offset: %#x\n",
-			le32_to_cpu(exfat->bs->bsx.clu_offset));
+	struct exfat *exfat = fsck->exfat;
+	struct exfat_inode *lostfound;
+	bitmap_t *disk_b, *alloc_b, *ohead_b;
+	struct exfat_dentry *dset;
+	clus_t clu_count, clu, s_clu, e_clu;
+	int err, dcount;
+	unsigned int i;
+	char name[] = "FILE0000000.CHK";
+	struct exfat_dentry_loc loc;
+	struct exfat_lookup_filter lf = {
+		.in.type = EXFAT_INVAL,
+		.in.dentry_count = 0,
+		.in.filter = NULL,
+	};
+
+	clu_count = le32_to_cpu(exfat->bs->bsx.clu_count);
+
+	/* find clusters which are not marked as free, but not allocated to
+	 * any files.
+	 */
+	disk_b = (bitmap_t *)exfat->disk_bitmap;
+	alloc_b = (bitmap_t *)exfat->alloc_bitmap;
+	ohead_b = (bitmap_t *)exfat->ohead_bitmap;
+	for (i = 0; i < EXFAT_BITMAP_SIZE(clu_count) / sizeof(bitmap_t); i++)
+		ohead_b[i] = disk_b[i] & ~alloc_b[i];
+
+	/* no orphan clusters */
+	if (exfat_bitmap_find_one(exfat, exfat->ohead_bitmap,
+				EXFAT_FIRST_CLUSTER, &s_clu))
+		return 0;
+
+	err = exfat_create_file(exfat_fsck.exfat,
+				exfat_fsck.exfat->root,
+				"LOST+FOUND",
+				ATTR_SUBDIR);
+	if (err) {
+		exfat_err("failed to create LOST+FOUND directory\n");
+		return err;
+	}
+
+	if (fsync(exfat_fsck.exfat->blk_dev->dev_fd) != 0) {
+		exfat_err("failed to sync()\n");
+		return -EIO;
+	}
+
+	err = read_lostfound(exfat, &lostfound);
+	if (err) {
+		exfat_err("failed to find LOST+FOUND\n");
+		return err;
+	}
+
+	/* get the last empty region of LOST+FOUND */
+	err = exfat_lookup_dentry_set(exfat, lostfound, &lf);
+	if (err && err != EOF) {
+		exfat_err("failed to find the last empty slot in LOST+FOUND\n");
+		goto out;
+	}
+
+	loc.parent = lostfound;
+	loc.file_offset = lf.out.file_offset;
+	loc.dev_offset = lf.out.dev_offset;
+
+	/* build a template dentry set */
+	err = exfat_build_file_dentry_set(exfat, name, 0, &dset, &dcount);
+	if (err) {
+		exfat_err("failed to create a temporary file in LOST+FOUNDn");
+		goto out;
+	}
+	dset[1].dentry.stream.flags |= EXFAT_SF_CONTIGUOUS;
+
+	/* create temporary files and allocate contiguous orphan clusters
+	 * to each file.
+	 */
+	for (clu = EXFAT_FIRST_CLUSTER; clu < clu_count + EXFAT_FIRST_CLUSTER &&
+	     exfat_bitmap_find_one(exfat, exfat->ohead_bitmap, clu, &s_clu) == 0;) {
+		if (exfat_bitmap_find_zero(exfat, exfat->ohead_bitmap, s_clu, &e_clu))
+			e_clu = clu_count + EXFAT_FIRST_CLUSTER;
+		clu = e_clu;
+
+		snprintf(name, sizeof(name), "FILE%07d.CHK",
+			 (unsigned int)(loc.file_offset >> 5));
+		err = exfat_update_file_dentry_set(exfat, dset, dcount,
+						   name, s_clu, e_clu - s_clu);
+		if (err)
+			continue;
+		err = exfat_add_dentry_set(exfat, &loc, dset, dcount, true);
+		if (err)
+			continue;
+	}
+
+	free(dset);
+	err = 0;
+out:
+	exfat_free_inode(lostfound);
+	return err;
 }
 
-void exfat_show_stat(void)
+static char *bytes_to_human_readable(size_t bytes)
 {
-	exfat_debug("Found directories: %ld\n", exfat_stat.dir_count);
-	exfat_debug("Found files: %ld\n", exfat_stat.file_count);
-	exfat_debug("Found leak directories: %ld\n",
-			exfat_stat.dir_count - exfat_stat.dir_free_count);
-	exfat_debug("Found leak files: %ld\n",
-			exfat_stat.file_count - exfat_stat.file_free_count);
+	static const char * const units[] = {"B", "KB", "MB", "GB", "TB", "PB"};
+	static char buf[15*4];
+	unsigned int i, shift, quoti, remain;
+	i = sizeof(units) / sizeof(units[0]) - 1;
+
+	while (i && (bytes >> i * 10) == 0)
+		i--;
+
+	shift = i * 10;
+	quoti = (unsigned int)(bytes / (1ULL << shift));
+	remain = 0;
+	if (shift > 0) {
+		remain = (unsigned int)
+			((bytes & ((1ULL << shift) - 1)) >> (shift - 10));
+		remain = (remain * 100) / 1024;
+	}
+
+	snprintf(buf, sizeof(buf), "%u.%02u %s", quoti, remain, units[i]);
+	return buf;
+}
+
+static void exfat_show_info(struct exfat_fsck *fsck, const char *dev_name)
+{
+	struct exfat *exfat = fsck->exfat;
+	bool clean;
+
+	exfat_info("sector size:  %s\n",
+		bytes_to_human_readable(1 << exfat->bs->bsx.sect_size_bits));
+	exfat_info("cluster size: %s\n",
+		bytes_to_human_readable(exfat->clus_size));
+	exfat_info("volume size:  %s\n",
+		bytes_to_human_readable(exfat->blk_dev->size));
+
+	clean = exfat_stat.error_count == 0 ||
+		exfat_stat.error_count == exfat_stat.fixed_count;
+	printf("%s: %s. directories %ld, files %ld\n", dev_name,
+			clean ? "clean" : "corrupted",
+			exfat_stat.dir_count, exfat_stat.file_count);
+	if (exfat_stat.error_count)
+		printf("%s: files corrupted %ld, files fixed %ld\n", dev_name,
+			exfat_stat.error_count - exfat_stat.fixed_count,
+			exfat_stat.fixed_count);
 }
 
 int main(int argc, char * const argv[])
 {
-	int c, ret;
 	struct fsck_user_input ui;
 	struct exfat_blk_dev bd;
-	struct exfat *exfat = NULL;
+	struct pbr *bs = NULL;
+	int c, ret, exit_code;
 	bool version_only = false;
 
 	memset(&ui, 0, sizeof(ui));
@@ -1229,25 +1466,34 @@ int main(int argc, char * const argv[])
 		exfat_err("failed to init locale/codeset\n");
 
 	opterr = 0;
-	while ((c = getopt_long(argc, argv, "rynVvh", opts, NULL)) != EOF) {
+	while ((c = getopt_long(argc, argv, "arynpbsVvh", opts, NULL)) != EOF) {
 		switch (c) {
 		case 'n':
-			if (ui.options & FSCK_OPTS_REPAIR)
+			if (ui.options & FSCK_OPTS_REPAIR_ALL)
 				usage(argv[0]);
 			ui.options |= FSCK_OPTS_REPAIR_NO;
-			ui.ei.writeable = false;
 			break;
 		case 'r':
-			if (ui.options & FSCK_OPTS_REPAIR)
+			if (ui.options & FSCK_OPTS_REPAIR_ALL)
 				usage(argv[0]);
 			ui.options |= FSCK_OPTS_REPAIR_ASK;
-			ui.ei.writeable = true;
 			break;
 		case 'y':
-			if (ui.options & FSCK_OPTS_REPAIR)
+			if (ui.options & FSCK_OPTS_REPAIR_ALL)
 				usage(argv[0]);
 			ui.options |= FSCK_OPTS_REPAIR_YES;
-			ui.ei.writeable = true;
+			break;
+		case 'a':
+		case 'p':
+			if (ui.options & FSCK_OPTS_REPAIR_ALL)
+				usage(argv[0]);
+			ui.options |= FSCK_OPTS_REPAIR_AUTO;
+			break;
+		case 'b':
+			ui.options |= FSCK_OPTS_IGNORE_BAD_FS_NAME;
+			break;
+		case 's':
+			ui.options |= FSCK_OPTS_RESCUE_CLUS;
 			break;
 		case 'V':
 			version_only = true;
@@ -1264,11 +1510,22 @@ int main(int argc, char * const argv[])
 	}
 
 	show_version();
+	if (optind != argc - 1)
+		usage(argv[0]);
+
 	if (version_only)
 		exit(FSCK_EXIT_SYNTAX_ERROR);
+	if (ui.options & FSCK_OPTS_REPAIR_WRITE)
+		ui.ei.writeable = true;
+	else {
+		if (ui.options & (FSCK_OPTS_IGNORE_BAD_FS_NAME |
+				  FSCK_OPTS_RESCUE_CLUS))
+			usage(argv[0]);
+		ui.options |= FSCK_OPTS_REPAIR_NO;
+		ui.ei.writeable = false;
+	}
 
-	if (optind != argc - 1)
-		usage(argv[0]);
+	exfat_fsck.options = ui.options;
 
 	snprintf(ui.ei.dev_name, sizeof(ui.ei.dev_name), "%s", argv[optind]);
 	ret = exfat_get_blk_dev_info(&ui.ei, &bd);
@@ -1277,44 +1534,83 @@ int main(int argc, char * const argv[])
 		return FSCK_EXIT_OPERATION_ERROR;
 	}
 
-	exfat = alloc_exfat(&bd);
-	if (!exfat) {
-		ret = FSCK_EXIT_OPERATION_ERROR;
+	ret = exfat_boot_region_check(&bd, &bs,
+				      ui.options & FSCK_OPTS_IGNORE_BAD_FS_NAME ?
+				      true : false);
+	if (ret)
+		goto err;
+
+	exfat_fsck.exfat = exfat_alloc_exfat(&bd, bs);
+	if (!exfat_fsck.exfat) {
+		ret = -ENOMEM;
 		goto err;
 	}
-	exfat->options = ui.options;
 
-	exfat_debug("verifying boot regions...\n");
-	if (!exfat_boot_region_check(exfat)) {
-		exfat_err("failed to verify boot regions.\n");
-		ret = FSCK_EXIT_ERRORS_LEFT;
+	exfat_fsck.buffer_desc = exfat_alloc_buffer(2,
+						    exfat_fsck.exfat->clus_size,
+						    exfat_fsck.exfat->sect_size);
+	if (!exfat_fsck.buffer_desc) {
+		ret = -ENOMEM;
 		goto err;
 	}
 
-	exfat_show_info(exfat);
+	if ((exfat_fsck.options & FSCK_OPTS_REPAIR_WRITE) &&
+	    exfat_mark_volume_dirty(exfat_fsck.exfat, true)) {
+		ret = -EIO;
+		goto err;
+	}
 
 	exfat_debug("verifying root directory...\n");
-	if (!exfat_root_dir_check(exfat)) {
+	ret = exfat_root_dir_check(exfat_fsck.exfat);
+	if (ret) {
 		exfat_err("failed to verify root directory.\n");
-		ret = FSCK_EXIT_ERRORS_LEFT;
 		goto out;
 	}
 
 	exfat_debug("verifying directory entries...\n");
-	if (!exfat_filesystem_check(exfat)) {
-		exfat_err("failed to verify directory entries.\n");
-		ret = FSCK_EXIT_ERRORS_LEFT;
+	ret = exfat_filesystem_check(&exfat_fsck);
+	if (ret)
+		goto out;
+
+	if (exfat_fsck.options & FSCK_OPTS_RESCUE_CLUS) {
+		rescue_orphan_clusters(&exfat_fsck);
+		exfat_fsck.dirty = true;
+		exfat_fsck.dirty_fat = true;
+	}
+
+	if (exfat_fsck.options & FSCK_OPTS_REPAIR_WRITE) {
+		ret = write_bitmap(&exfat_fsck);
+		if (ret) {
+			exfat_err("failed to write bitmap\n");
+			goto out;
+		}
+	}
+
+	if (ui.ei.writeable && fsync(bd.dev_fd)) {
+		exfat_err("failed to sync\n");
+		ret = -EIO;
 		goto out;
 	}
+	if (exfat_fsck.options & FSCK_OPTS_REPAIR_WRITE)
+		exfat_mark_volume_dirty(exfat_fsck.exfat, false);
 
-	if (ui.ei.writeable)
-		fsync(bd.dev_fd);
-	printf("%s: clean\n", ui.ei.dev_name);
-	ret = FSCK_EXIT_NO_ERRORS;
 out:
-	exfat_show_stat();
+	exfat_show_info(&exfat_fsck, ui.ei.dev_name);
 err:
-	free_exfat(exfat);
+	if (ret && ret != -EINVAL)
+		exit_code = FSCK_EXIT_OPERATION_ERROR;
+	else if (ret == -EINVAL ||
+		 exfat_stat.error_count != exfat_stat.fixed_count)
+		exit_code = FSCK_EXIT_ERRORS_LEFT;
+	else if (exfat_fsck.dirty)
+		exit_code = FSCK_EXIT_CORRECTED;
+	else
+		exit_code = FSCK_EXIT_NO_ERRORS;
+
+	if (exfat_fsck.buffer_desc)
+		exfat_free_buffer(exfat_fsck.buffer_desc, 2);
+	if (exfat_fsck.exfat)
+		exfat_free_exfat(exfat_fsck.exfat);
 	close(bd.dev_fd);
-	return ret;
+	return exit_code;
 }