diff mbox series

[v6,07/13] exfat: add bitmap operations

Message ID 20191209065149.2230-8-namjae.jeon@samsung.com (mailing list archive)
State New, archived
Headers show
Series add the latest exfat driver | expand

Commit Message

Namjae Jeon Dec. 9, 2019, 6:51 a.m. UTC 
This adds the implementation of bitmap operations for exfat.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Sungjong Seo <sj1557.seo@samsung.com>
---
 fs/exfat/balloc.c | 272 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 272 insertions(+)
 create mode 100644 fs/exfat/balloc.c

Comments

Viacheslav Dubeyko Dec. 9, 2019, 12:07 p.m. UTC | #1 
On Mon, 2019-12-09 at 01:51 -0500, Namjae Jeon wrote:
> This adds the implementation of bitmap operations for exfat.
> 
> Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
> Signed-off-by: Sungjong Seo <sj1557.seo@samsung.com>
> ---
>  fs/exfat/balloc.c | 272
> ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 272 insertions(+)
>  create mode 100644 fs/exfat/balloc.c
> 
> diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c
> new file mode 100644
> index 000000000000..d7b70620e349
> --- /dev/null
> +++ b/fs/exfat/balloc.c
> @@ -0,0 +1,272 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + *  Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
> + */
> +
> +#include <linux/blkdev.h>
> +#include <linux/slab.h>
> +#include <linux/buffer_head.h>
> +
> +#include "exfat_raw.h"
> +#include "exfat_fs.h"
> +
> +static const unsigned char free_bit[] = {
> +	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0,
> 2,/*  0 ~  19*/
> +	0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5, 0, 1, 0, 2, 0, 1, 0, 3,/*
> 20 ~  39*/
> +	0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/*
> 40 ~  59*/
> +	0, 1, 0, 6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4,/*
> 60 ~  79*/
> +	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5, 0, 1, 0, 2,/*
> 80 ~  99*/
> +	0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0,
> 3,/*100 ~ 119*/
> +	0, 1, 0, 2, 0, 1, 0, 7, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0,
> 2,/*120 ~ 139*/
> +	0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
> 5,/*140 ~ 159*/
> +	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0,
> 2,/*160 ~ 179*/
> +	0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 6, 0, 1, 0, 2, 0, 1, 0,
> 3,/*180 ~ 199*/
> +	0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0,
> 2,/*200 ~ 219*/
> +	0, 1, 0, 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0,
> 4,/*220 ~ 239*/
> +	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1,
> 0                /*240 ~ 254*/
> +};
> +
> +static const unsigned char used_bit[] = {
> +	0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, 1, 2, 2,
> 3,/*  0 ~  19*/
> +	2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 1, 2, 2, 3, 2, 3, 3, 4,/*
> 20 ~  39*/
> +	2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5,/*
> 40 ~  59*/
> +	4, 5, 5, 6, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,/*
> 60 ~  79*/
> +	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 2, 3, 3, 4,/*
> 80 ~  99*/
> +	3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5,
> 6,/*100 ~ 119*/
> +	4, 5, 5, 6, 5, 6, 6, 7, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3,
> 4,/*120 ~ 139*/
> +	3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5,
> 6,/*140 ~ 159*/
> +	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4,
> 5,/*160 ~ 179*/
> +	4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 2, 3, 3, 4, 3, 4, 4,
> 5,/*180 ~ 199*/
> +	3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5,
> 6,/*200 ~ 219*/
> +	5, 6, 6, 7, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6,
> 7,/*220 ~ 239*/
> +	4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7,
> 8             /*240 ~ 255*/
> +};
> +
> +/*
> + *  Allocation Bitmap Management Functions
> + */
> +static int exfat_allocate_bitmap(struct super_block *sb,
> +		struct exfat_dentry *ep)
> +{
> +	struct exfat_sb_info *sbi = EXFAT_SB(sb);
> +	long long map_size;
> +	unsigned int i, need_map_size;
> +	sector_t sector;
> +
> +	sbi->map_clu = le32_to_cpu(ep->bitmap_start_clu);
> +	map_size = le64_to_cpu(ep->bitmap_size);
> +	need_map_size = (((sbi->num_clusters - BASE_CLUSTER) - 1) >> 3)
> + 1;

This code is slightly complicated. Why 3 was used here? Maybe it makes
sense to refactor this code and to make it more clear?

> +	if (need_map_size != map_size) {
> +		exfat_msg(sb, KERN_ERR,
> +				"bogus allocation bitmap size(need :
> %u, cur : %lld)",
> +				need_map_size, map_size);
> +		/*
> +		 * Only allowed when bogus allocation
> +		 * bitmap size is large
> +		 */
> +		if (need_map_size > map_size)
> +			return -EIO;
> +	}
> +	sbi->map_sectors = ((need_map_size - 1) >>
> +			(sb->s_blocksize_bits)) + 1;
> +	sbi->vol_amap = kmalloc_array(sbi->map_sectors,
> +				sizeof(struct buffer_head *),
> GFP_KERNEL);
> +	if (!sbi->vol_amap)
> +		return -ENOMEM;
> +
> +	sector = exfat_cluster_to_sector(sbi, sbi->map_clu);
> +	for (i = 0; i < sbi->map_sectors; i++) {
> +		sbi->vol_amap[i] = sb_bread(sb, sector + i);
> +		if (!sbi->vol_amap[i]) {
> +			/* release all buffers and free vol_amap */
> +			int j = 0;
> +
> +			while (j < i)
> +				brelse(sbi->vol_amap[j++]);
> +
> +			kfree(sbi->vol_amap);
> +			sbi->vol_amap = NULL;
> +			return -EIO;
> +		}
> +	}
> +
> +	sbi->pbr_bh = NULL;
> +	return 0;
> +}
> +
> +int exfat_load_bitmap(struct super_block *sb)
> +{
> +	unsigned int i, type;
> +	struct exfat_chain clu;
> +	struct exfat_sb_info *sbi = EXFAT_SB(sb);
> +
> +	exfat_chain_set(&clu, sbi->root_dir, 0, ALLOC_FAT_CHAIN);
> +
> +	while (clu.dir != EOF_CLUSTER) {
> +		for (i = 0; i < sbi->dentries_per_clu; i++) {
> +			struct exfat_dentry *ep;
> +			struct buffer_head *bh;
> +
> +			ep = exfat_get_dentry(sb, &clu, i, &bh, NULL);
> +			if (!ep)
> +				return -EIO;
> +
> +			type = exfat_get_entry_type(ep);
> +			if (type == TYPE_UNUSED)
> +				break;
> +			if (type != TYPE_BITMAP)
> +				continue;
> +			if (ep->bitmap_flags == 0x0) {
> +				int err;
> +
> +				err = exfat_allocate_bitmap(sb, ep);
> +				brelse(bh);
> +				return err;
> +			}
> +			brelse(bh);
> +		}
> +
> +		if (exfat_get_next_cluster(sb, &clu.dir))
> +			return -EIO;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +void exfat_free_bitmap(struct super_block *sb)
> +{
> +	int i;
> +	struct exfat_sb_info *sbi = EXFAT_SB(sb);
> +
> +	brelse(sbi->pbr_bh);
> +
> +	for (i = 0; i < sbi->map_sectors; i++)
> +		__brelse(sbi->vol_amap[i]);
> +
> +	kfree(sbi->vol_amap);
> +	sbi->vol_amap = NULL;
> +}
> +
> +/*
> + * If the value of "clu" is 0, it means cluster 2 which is the first
> cluster of
> + * the cluster heap.
> + */
> +int exfat_set_bitmap(struct inode *inode, unsigned int clu)
> +{
> +	int i, b;
> +	struct super_block *sb = inode->i_sb;
> +	struct exfat_sb_info *sbi = EXFAT_SB(sb);
> +
> +	i = clu >> (sb->s_blocksize_bits + 3);
> +	b = clu & ((sb->s_blocksize << 3) - 1);

This code looks like the dark magic. I believe it makes sense to
introduce some constant for 3 here.

> +
> +	set_bit_le(b, sbi->vol_amap[i]->b_data);
> +	exfat_update_bh(sb, sbi->vol_amap[i], IS_DIRSYNC(inode));
> +	return 0;
> +}
> +
> +/*
> + * If the value of "clu" is 0, it means cluster 2 which is the first
> cluster of
> + * the cluster heap.
> + */
> +void exfat_clear_bitmap(struct inode *inode, unsigned int clu)
> +{
> +	int i, b;
> +	struct super_block *sb = inode->i_sb;
> +	struct exfat_sb_info *sbi = EXFAT_SB(sb);
> +	struct exfat_mount_options *opts = &sbi->options;
> +
> +	i = clu >> (sb->s_blocksize_bits + 3);
> +	b = clu & ((sb->s_blocksize << 3) - 1);
> +

Ditto.

> +	clear_bit_le(b, sbi->vol_amap[i]->b_data);
> +	exfat_update_bh(sb, sbi->vol_amap[i], IS_DIRSYNC(inode));
> +
> +	if (opts->discard) {
> +		int ret_discard;
> +
> +		ret_discard = sb_issue_discard(sb,
> +				exfat_cluster_to_sector(sbi, clu + 2),
> +				(1 << sbi->sect_per_clus_bits),
> GFP_NOFS, 0);

Why clu + 2? It's unclear, frankly speaking.

> +
> +		if (ret_discard == -EOPNOTSUPP) {
> +			exfat_msg(sb, KERN_ERR,
> +				"discard not supported by device,
> disabling");
> +			opts->discard = 0;
> +		}
> +	}
> +}
> +
> +/*
> + * If the value of "clu" is 0, it means cluster 2 which is the first
> cluster of
> + * the cluster heap.
> + */
> +unsigned int exfat_test_bitmap(struct super_block *sb, unsigned int
> clu)
> +{
> +	unsigned int i, map_i, map_b;
> +	unsigned int clu_base, clu_free;
> +	unsigned char k, clu_mask;
> +	struct exfat_sb_info *sbi = EXFAT_SB(sb);
> +
> +	clu_base = (clu & ~(0x7)) + 2;
> +	clu_mask = (1 << (clu - clu_base + 2)) - 1;
> +

What does 0x7 mean here? Why clu - clu_base + 2? Maybe it need to
introduce some constants and to add some comments?

> +	map_i = clu >> (sb->s_blocksize_bits + 3);
> +	map_b = (clu >> 3) & (unsigned int)(sb->s_blocksize - 1);
> +

Ditto.

> +	for (i = 2; i < sbi->num_clusters; i += 8) {


Why we start from 2 and add 8? Maybe introduce some constants?

> +		k = *(sbi->vol_amap[map_i]->b_data + map_b);
> +		if (clu_mask > 0) {
> +			k |= clu_mask;
> +			clu_mask = 0;
> +		}
> +		if (k < 0xFF) {
> +			clu_free = clu_base + free_bit[k];
> +			if (clu_free < sbi->num_clusters)
> +				return clu_free;
> +		}
> +		clu_base += 8;

Ditto.

> +
> +		if (++map_b >= sb->s_blocksize ||
> +		    clu_base >= sbi->num_clusters) {
> +			if (++map_i >= sbi->map_sectors) {
> +				clu_base = 2;
> +				map_i = 0;
> +			}
> +			map_b = 0;
> +		}
> +	}
> +
> +	return EOF_CLUSTER;
> +}
> +
> +int exfat_count_used_clusters(struct super_block *sb, unsigned int
> *ret_count)
> +{
> +	struct exfat_sb_info *sbi = EXFAT_SB(sb);
> +	unsigned int count = 0;
> +	unsigned int i, map_i = 0, map_b = 0;
> +	unsigned int total_clus = sbi->num_clusters - 2;
> +	unsigned int last_mask = total_clus & 7;

Ditto.

> +	unsigned char clu_bits;
> +	const unsigned char last_bit_mask[] = {0, 0b00000001,
> 0b00000011,
> +		0b00000111, 0b00001111, 0b00011111, 0b00111111,
> 0b01111111};
> +
> +	total_clus &= ~last_mask;
> +	for (i = 0; i < total_clus; i += 8) {

Ditto.

Thanks,
Viacheslav Dubeyko.

> +		clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
> +		count += used_bit[clu_bits];
> +		if (++map_b >= (unsigned int)sb->s_blocksize) {
> +			map_i++;
> +			map_b = 0;
> +		}
> +	}
> +
> +	if (last_mask) {
> +		clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
> +		clu_bits &= last_bit_mask[last_mask];
> +		count += used_bit[clu_bits];
> +	}
> +
> +	*ret_count = count;
> +	return 0;
> +}
diff mbox series

Patch

diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c
new file mode 100644
index 000000000000..d7b70620e349
--- /dev/null
+++ b/fs/exfat/balloc.c
@@ -0,0 +1,272 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
+ */
+
+#include <linux/blkdev.h>
+#include <linux/slab.h>
+#include <linux/buffer_head.h>
+
+#include "exfat_raw.h"
+#include "exfat_fs.h"
+
+static const unsigned char free_bit[] = {
+	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2,/*  0 ~  19*/
+	0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5, 0, 1, 0, 2, 0, 1, 0, 3,/* 20 ~  39*/
+	0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/* 40 ~  59*/
+	0, 1, 0, 6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4,/* 60 ~  79*/
+	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5, 0, 1, 0, 2,/* 80 ~  99*/
+	0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3,/*100 ~ 119*/
+	0, 1, 0, 2, 0, 1, 0, 7, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/*120 ~ 139*/
+	0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5,/*140 ~ 159*/
+	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2,/*160 ~ 179*/
+	0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 6, 0, 1, 0, 2, 0, 1, 0, 3,/*180 ~ 199*/
+	0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/*200 ~ 219*/
+	0, 1, 0, 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4,/*220 ~ 239*/
+	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0                /*240 ~ 254*/
+};
+
+static const unsigned char used_bit[] = {
+	0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, 1, 2, 2, 3,/*  0 ~  19*/
+	2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 1, 2, 2, 3, 2, 3, 3, 4,/* 20 ~  39*/
+	2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5,/* 40 ~  59*/
+	4, 5, 5, 6, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,/* 60 ~  79*/
+	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 2, 3, 3, 4,/* 80 ~  99*/
+	3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6,/*100 ~ 119*/
+	4, 5, 5, 6, 5, 6, 6, 7, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4,/*120 ~ 139*/
+	3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,/*140 ~ 159*/
+	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5,/*160 ~ 179*/
+	4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 2, 3, 3, 4, 3, 4, 4, 5,/*180 ~ 199*/
+	3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6,/*200 ~ 219*/
+	5, 6, 6, 7, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,/*220 ~ 239*/
+	4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8             /*240 ~ 255*/
+};
+
+/*
+ *  Allocation Bitmap Management Functions
+ */
+static int exfat_allocate_bitmap(struct super_block *sb,
+		struct exfat_dentry *ep)
+{
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+	long long map_size;
+	unsigned int i, need_map_size;
+	sector_t sector;
+
+	sbi->map_clu = le32_to_cpu(ep->bitmap_start_clu);
+	map_size = le64_to_cpu(ep->bitmap_size);
+	need_map_size = (((sbi->num_clusters - BASE_CLUSTER) - 1) >> 3) + 1;
+	if (need_map_size != map_size) {
+		exfat_msg(sb, KERN_ERR,
+				"bogus allocation bitmap size(need : %u, cur : %lld)",
+				need_map_size, map_size);
+		/*
+		 * Only allowed when bogus allocation
+		 * bitmap size is large
+		 */
+		if (need_map_size > map_size)
+			return -EIO;
+	}
+	sbi->map_sectors = ((need_map_size - 1) >>
+			(sb->s_blocksize_bits)) + 1;
+	sbi->vol_amap = kmalloc_array(sbi->map_sectors,
+				sizeof(struct buffer_head *), GFP_KERNEL);
+	if (!sbi->vol_amap)
+		return -ENOMEM;
+
+	sector = exfat_cluster_to_sector(sbi, sbi->map_clu);
+	for (i = 0; i < sbi->map_sectors; i++) {
+		sbi->vol_amap[i] = sb_bread(sb, sector + i);
+		if (!sbi->vol_amap[i]) {
+			/* release all buffers and free vol_amap */
+			int j = 0;
+
+			while (j < i)
+				brelse(sbi->vol_amap[j++]);
+
+			kfree(sbi->vol_amap);
+			sbi->vol_amap = NULL;
+			return -EIO;
+		}
+	}
+
+	sbi->pbr_bh = NULL;
+	return 0;
+}
+
+int exfat_load_bitmap(struct super_block *sb)
+{
+	unsigned int i, type;
+	struct exfat_chain clu;
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+
+	exfat_chain_set(&clu, sbi->root_dir, 0, ALLOC_FAT_CHAIN);
+
+	while (clu.dir != EOF_CLUSTER) {
+		for (i = 0; i < sbi->dentries_per_clu; i++) {
+			struct exfat_dentry *ep;
+			struct buffer_head *bh;
+
+			ep = exfat_get_dentry(sb, &clu, i, &bh, NULL);
+			if (!ep)
+				return -EIO;
+
+			type = exfat_get_entry_type(ep);
+			if (type == TYPE_UNUSED)
+				break;
+			if (type != TYPE_BITMAP)
+				continue;
+			if (ep->bitmap_flags == 0x0) {
+				int err;
+
+				err = exfat_allocate_bitmap(sb, ep);
+				brelse(bh);
+				return err;
+			}
+			brelse(bh);
+		}
+
+		if (exfat_get_next_cluster(sb, &clu.dir))
+			return -EIO;
+	}
+
+	return -EINVAL;
+}
+
+void exfat_free_bitmap(struct super_block *sb)
+{
+	int i;
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+
+	brelse(sbi->pbr_bh);
+
+	for (i = 0; i < sbi->map_sectors; i++)
+		__brelse(sbi->vol_amap[i]);
+
+	kfree(sbi->vol_amap);
+	sbi->vol_amap = NULL;
+}
+
+/*
+ * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
+ * the cluster heap.
+ */
+int exfat_set_bitmap(struct inode *inode, unsigned int clu)
+{
+	int i, b;
+	struct super_block *sb = inode->i_sb;
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+
+	i = clu >> (sb->s_blocksize_bits + 3);
+	b = clu & ((sb->s_blocksize << 3) - 1);
+
+	set_bit_le(b, sbi->vol_amap[i]->b_data);
+	exfat_update_bh(sb, sbi->vol_amap[i], IS_DIRSYNC(inode));
+	return 0;
+}
+
+/*
+ * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
+ * the cluster heap.
+ */
+void exfat_clear_bitmap(struct inode *inode, unsigned int clu)
+{
+	int i, b;
+	struct super_block *sb = inode->i_sb;
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+	struct exfat_mount_options *opts = &sbi->options;
+
+	i = clu >> (sb->s_blocksize_bits + 3);
+	b = clu & ((sb->s_blocksize << 3) - 1);
+
+	clear_bit_le(b, sbi->vol_amap[i]->b_data);
+	exfat_update_bh(sb, sbi->vol_amap[i], IS_DIRSYNC(inode));
+
+	if (opts->discard) {
+		int ret_discard;
+
+		ret_discard = sb_issue_discard(sb,
+				exfat_cluster_to_sector(sbi, clu + 2),
+				(1 << sbi->sect_per_clus_bits), GFP_NOFS, 0);
+
+		if (ret_discard == -EOPNOTSUPP) {
+			exfat_msg(sb, KERN_ERR,
+				"discard not supported by device, disabling");
+			opts->discard = 0;
+		}
+	}
+}
+
+/*
+ * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
+ * the cluster heap.
+ */
+unsigned int exfat_test_bitmap(struct super_block *sb, unsigned int clu)
+{
+	unsigned int i, map_i, map_b;
+	unsigned int clu_base, clu_free;
+	unsigned char k, clu_mask;
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+
+	clu_base = (clu & ~(0x7)) + 2;
+	clu_mask = (1 << (clu - clu_base + 2)) - 1;
+
+	map_i = clu >> (sb->s_blocksize_bits + 3);
+	map_b = (clu >> 3) & (unsigned int)(sb->s_blocksize - 1);
+
+	for (i = 2; i < sbi->num_clusters; i += 8) {
+		k = *(sbi->vol_amap[map_i]->b_data + map_b);
+		if (clu_mask > 0) {
+			k |= clu_mask;
+			clu_mask = 0;
+		}
+		if (k < 0xFF) {
+			clu_free = clu_base + free_bit[k];
+			if (clu_free < sbi->num_clusters)
+				return clu_free;
+		}
+		clu_base += 8;
+
+		if (++map_b >= sb->s_blocksize ||
+		    clu_base >= sbi->num_clusters) {
+			if (++map_i >= sbi->map_sectors) {
+				clu_base = 2;
+				map_i = 0;
+			}
+			map_b = 0;
+		}
+	}
+
+	return EOF_CLUSTER;
+}
+
+int exfat_count_used_clusters(struct super_block *sb, unsigned int *ret_count)
+{
+	struct exfat_sb_info *sbi = EXFAT_SB(sb);
+	unsigned int count = 0;
+	unsigned int i, map_i = 0, map_b = 0;
+	unsigned int total_clus = sbi->num_clusters - 2;
+	unsigned int last_mask = total_clus & 7;
+	unsigned char clu_bits;
+	const unsigned char last_bit_mask[] = {0, 0b00000001, 0b00000011,
+		0b00000111, 0b00001111, 0b00011111, 0b00111111, 0b01111111};
+
+	total_clus &= ~last_mask;
+	for (i = 0; i < total_clus; i += 8) {
+		clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
+		count += used_bit[clu_bits];
+		if (++map_b >= (unsigned int)sb->s_blocksize) {
+			map_i++;
+			map_b = 0;
+		}
+	}
+
+	if (last_mask) {
+		clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
+		clu_bits &= last_bit_mask[last_mask];
+		count += used_bit[clu_bits];
+	}
+
+	*ret_count = count;
+	return 0;
+}