From 1e49a94cf707204b66a3fb242f2814712c941f52 Mon Sep 17 00:00:00 2001

From: Namjae Jeon <namjae.jeon@samsung.com>

Date: Mon, 2 Mar 2020 15:21:38 +0900

Subject: [Backport 1e49a94cf707] exfat: add bitmap operations

MIME-Version: 1.0

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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>

Reviewed-by: Pali Rohár <pali.rohar@gmail.com>

Reviewed-by: Christoph Hellwig <hch@lst.de>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

---

 src/balloc.c | 280 ++++++++++++++++++++++++++++++++++++++++++++++

 1 file changed, 280 insertions(+)

 create mode 100644 src/balloc.c

diff --git a/src/balloc.c b/src/balloc.c

new file mode 100644

index 0000000000000000000000000000000000000000..6a04cc02565a1f3823ad9a109238bad9553a82f1

--- /dev/null

+++ b/src/balloc.c

@@ -0,0 +1,280 @@

+// 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->dentry.bitmap.start_clu);

+	map_size = le64_to_cpu(ep->dentry.bitmap.size);

+	need_map_size = ((EXFAT_DATA_CLUSTER_COUNT(sbi) - 1) / BITS_PER_BYTE)

+		+ 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 != EXFAT_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->dentry.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 exfat_sb_info *sbi)

+{

+	int i;

+

+	brelse(sbi->pbr_bh);

+

+	for (i = 0; i < sbi->map_sectors; i++)

+		__brelse(sbi->vol_amap[i]);

+

+	kfree(sbi->vol_amap);

+}

+

+/*

+ * 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;

+	unsigned int ent_idx;

+	struct super_block *sb = inode->i_sb;

+	struct exfat_sb_info *sbi = EXFAT_SB(sb);

+

+	WARN_ON(clu < EXFAT_FIRST_CLUSTER);

+	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);

+	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);

+	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);

+

+	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;

+	unsigned int ent_idx;

+	struct super_block *sb = inode->i_sb;

+	struct exfat_sb_info *sbi = EXFAT_SB(sb);

+	struct exfat_mount_options *opts = &sbi->options;

+

+	WARN_ON(clu < EXFAT_FIRST_CLUSTER);

+	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);

+	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);

+	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);

+

+	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 +

+						EXFAT_RESERVED_CLUSTERS),

+			(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_find_free_bitmap(struct super_block *sb, unsigned int clu)

+{

+	unsigned int i, map_i, map_b, ent_idx;

+	unsigned int clu_base, clu_free;

+	unsigned char k, clu_mask;

+	struct exfat_sb_info *sbi = EXFAT_SB(sb);

+

+	WARN_ON(clu < EXFAT_FIRST_CLUSTER);

+	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);

+	clu_base = BITMAP_ENT_TO_CLUSTER(ent_idx & ~(BITS_PER_BYTE_MASK));

+	clu_mask = IGNORED_BITS_REMAINED(clu, clu_base);

+

+	map_i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);

+	map_b = BITMAP_OFFSET_BYTE_IN_SECTOR(sb, ent_idx);

+

+	for (i = EXFAT_FIRST_CLUSTER; i < sbi->num_clusters;

+	     i += BITS_PER_BYTE) {

+		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 += BITS_PER_BYTE;

+

+		if (++map_b >= sb->s_blocksize ||

+		    clu_base >= sbi->num_clusters) {

+			if (++map_i >= sbi->map_sectors) {

+				clu_base = EXFAT_FIRST_CLUSTER;

+				map_i = 0;

+			}

+			map_b = 0;

+		}

+	}

+

+	return EXFAT_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 = EXFAT_DATA_CLUSTER_COUNT(sbi);

+	unsigned int last_mask = total_clus & BITS_PER_BYTE_MASK;

+	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 += BITS_PER_BYTE) {

+		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;

+}

-- 

2.31.1