[PATCH v12 07/13] exfat: add bitmap operations

Namjae Jeon
2020-01-20T12:45:12Z

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: Christoph Hellwig <hch@lst.de>
Reviewed-by: Pali Rohár <pali.rohar@gmail.com>
---
fs/exfat/balloc.c | 282 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 282 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..b568f5efc984
--- /dev/null
+++ b/fs/exfat/balloc.c
@@ -0,0 +1,282 @@
+// 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 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;
+ 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;
+}
--
2.17.1