exfat: add bitmap operations

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>

diff --git a/fs/exfat/balloc.c b/fs/exfat/balloc.c
new file mode 100644 (file)
index 0000000..6a04cc0
--- /dev/null
+++ b/fs/exfat/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;
+}