fs/exfat/balloc.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
   4  */
   5
   6 #include <linux/blkdev.h>
   7 #include <linux/slab.h>
   8 #include <linux/buffer_head.h>
   9
  10 #include "exfat_raw.h"
  11 #include "exfat_fs.h"
  12
  13 static const unsigned char free_bit[] = {
  14         0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2,/*  0 ~  19*/
  15         0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5, 0, 1, 0, 2, 0, 1, 0, 3,/* 20 ~  39*/
  16         0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/* 40 ~  59*/
  17         0, 1, 0, 6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4,/* 60 ~  79*/
  18         0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5, 0, 1, 0, 2,/* 80 ~  99*/
  19         0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3,/*100 ~ 119*/
  20         0, 1, 0, 2, 0, 1, 0, 7, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/*120 ~ 139*/
  21         0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5,/*140 ~ 159*/
  22         0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2,/*160 ~ 179*/
  23         0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 6, 0, 1, 0, 2, 0, 1, 0, 3,/*180 ~ 199*/
  24         0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/*200 ~ 219*/
  25         0, 1, 0, 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4,/*220 ~ 239*/
  26         0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0                /*240 ~ 254*/
  27 };
  28
  29 static const unsigned char used_bit[] = {
  30         0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, 1, 2, 2, 3,/*  0 ~  19*/
  31         2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 1, 2, 2, 3, 2, 3, 3, 4,/* 20 ~  39*/
  32         2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5,/* 40 ~  59*/
  33         4, 5, 5, 6, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,/* 60 ~  79*/
  34         2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 2, 3, 3, 4,/* 80 ~  99*/
  35         3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6,/*100 ~ 119*/
  36         4, 5, 5, 6, 5, 6, 6, 7, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4,/*120 ~ 139*/
  37         3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,/*140 ~ 159*/
  38         2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5,/*160 ~ 179*/
  39         4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 2, 3, 3, 4, 3, 4, 4, 5,/*180 ~ 199*/
  40         3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6,/*200 ~ 219*/
  41         5, 6, 6, 7, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,/*220 ~ 239*/
  42         4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8             /*240 ~ 255*/
  43 };
  44
  45 /*
  46  *  Allocation Bitmap Management Functions
  47  */
  48 static int exfat_allocate_bitmap(struct super_block *sb,
  49                 struct exfat_dentry *ep)
  50 {
  51         struct exfat_sb_info *sbi = EXFAT_SB(sb);
  52         long long map_size;
  53         unsigned int i, need_map_size;
  54         sector_t sector;
  55
  56         sbi->map_clu = le32_to_cpu(ep->dentry.bitmap.start_clu);
  57         map_size = le64_to_cpu(ep->dentry.bitmap.size);
  58         need_map_size = ((EXFAT_DATA_CLUSTER_COUNT(sbi) - 1) / BITS_PER_BYTE)
  59                 + 1;
  60         if (need_map_size != map_size) {
  61                 exfat_err(sb, "bogus allocation bitmap size(need : %u, cur : %lld)",
  62                           need_map_size, map_size);
  63                 /*
  64                  * Only allowed when bogus allocation
  65                  * bitmap size is large
  66                  */
  67                 if (need_map_size > map_size)
  68                         return -EIO;
  69         }
  70         sbi->map_sectors = ((need_map_size - 1) >>
  71                         (sb->s_blocksize_bits)) + 1;
  72         sbi->vol_amap = kmalloc_array(sbi->map_sectors,
  73                                 sizeof(struct buffer_head *), GFP_KERNEL);
  74         if (!sbi->vol_amap)
  75                 return -ENOMEM;
  76
  77         sector = exfat_cluster_to_sector(sbi, sbi->map_clu);
  78         for (i = 0; i < sbi->map_sectors; i++) {
  79                 sbi->vol_amap[i] = sb_bread(sb, sector + i);
  80                 if (!sbi->vol_amap[i]) {
  81                         /* release all buffers and free vol_amap */
  82                         int j = 0;
  83
  84                         while (j < i)
  85                                 brelse(sbi->vol_amap[j++]);
  86
  87                         kfree(sbi->vol_amap);
  88                         sbi->vol_amap = NULL;
  89                         return -EIO;
  90                 }
  91         }
  92
  93         return 0;
  94 }
  95
  96 int exfat_load_bitmap(struct super_block *sb)
  97 {
  98         unsigned int i, type;
  99         struct exfat_chain clu;
 100         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 101
 102         exfat_chain_set(&clu, sbi->root_dir, 0, ALLOC_FAT_CHAIN);
 103         while (clu.dir != EXFAT_EOF_CLUSTER) {
 104                 for (i = 0; i < sbi->dentries_per_clu; i++) {
 105                         struct exfat_dentry *ep;
 106                         struct buffer_head *bh;
 107
 108                         ep = exfat_get_dentry(sb, &clu, i, &bh, NULL);
 109                         if (!ep)
 110                                 return -EIO;
 111
 112                         type = exfat_get_entry_type(ep);
 113                         if (type == TYPE_UNUSED)
 114                                 break;
 115                         if (type != TYPE_BITMAP)
 116                                 continue;
 117                         if (ep->dentry.bitmap.flags == 0x0) {
 118                                 int err;
 119
 120                                 err = exfat_allocate_bitmap(sb, ep);
 121                                 brelse(bh);
 122                                 return err;
 123                         }
 124                         brelse(bh);
 125                 }
 126
 127                 if (exfat_get_next_cluster(sb, &clu.dir))
 128                         return -EIO;
 129         }
 130
 131         return -EINVAL;
 132 }
 133
 134 void exfat_free_bitmap(struct exfat_sb_info *sbi)
 135 {
 136         int i;
 137
 138         for (i = 0; i < sbi->map_sectors; i++)
 139                 __brelse(sbi->vol_amap[i]);
 140
 141         kfree(sbi->vol_amap);
 142 }
 143
 144 /*
 145  * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
 146  * the cluster heap.
 147  */
 148 int exfat_set_bitmap(struct inode *inode, unsigned int clu)
 149 {
 150         int i, b;
 151         unsigned int ent_idx;
 152         struct super_block *sb = inode->i_sb;
 153         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 154
 155         WARN_ON(clu < EXFAT_FIRST_CLUSTER);
 156         ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
 157         i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
 158         b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
 159
 160         set_bit_le(b, sbi->vol_amap[i]->b_data);
 161         exfat_update_bh(sbi->vol_amap[i], IS_DIRSYNC(inode));
 162         return 0;
 163 }
 164
 165 /*
 166  * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
 167  * the cluster heap.
 168  */
 169 void exfat_clear_bitmap(struct inode *inode, unsigned int clu)
 170 {
 171         int i, b;
 172         unsigned int ent_idx;
 173         struct super_block *sb = inode->i_sb;
 174         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 175         struct exfat_mount_options *opts = &sbi->options;
 176
 177         WARN_ON(clu < EXFAT_FIRST_CLUSTER);
 178         ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
 179         i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
 180         b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
 181
 182         clear_bit_le(b, sbi->vol_amap[i]->b_data);
 183         exfat_update_bh(sbi->vol_amap[i], IS_DIRSYNC(inode));
 184
 185         if (opts->discard) {
 186                 int ret_discard;
 187
 188                 ret_discard = sb_issue_discard(sb,
 189                         exfat_cluster_to_sector(sbi, clu +
 190                                                 EXFAT_RESERVED_CLUSTERS),
 191                         (1 << sbi->sect_per_clus_bits), GFP_NOFS, 0);
 192
 193                 if (ret_discard == -EOPNOTSUPP) {
 194                         exfat_err(sb, "discard not supported by device, disabling");
 195                         opts->discard = 0;
 196                 }
 197         }
 198 }
 199
 200 /*
 201  * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
 202  * the cluster heap.
 203  */
 204 unsigned int exfat_find_free_bitmap(struct super_block *sb, unsigned int clu)
 205 {
 206         unsigned int i, map_i, map_b, ent_idx;
 207         unsigned int clu_base, clu_free;
 208         unsigned char k, clu_mask;
 209         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 210
 211         WARN_ON(clu < EXFAT_FIRST_CLUSTER);
 212         ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
 213         clu_base = BITMAP_ENT_TO_CLUSTER(ent_idx & ~(BITS_PER_BYTE_MASK));
 214         clu_mask = IGNORED_BITS_REMAINED(clu, clu_base);
 215
 216         map_i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
 217         map_b = BITMAP_OFFSET_BYTE_IN_SECTOR(sb, ent_idx);
 218
 219         for (i = EXFAT_FIRST_CLUSTER; i < sbi->num_clusters;
 220              i += BITS_PER_BYTE) {
 221                 k = *(sbi->vol_amap[map_i]->b_data + map_b);
 222                 if (clu_mask > 0) {
 223                         k |= clu_mask;
 224                         clu_mask = 0;
 225                 }
 226                 if (k < 0xFF) {
 227                         clu_free = clu_base + free_bit[k];
 228                         if (clu_free < sbi->num_clusters)
 229                                 return clu_free;
 230                 }
 231                 clu_base += BITS_PER_BYTE;
 232
 233                 if (++map_b >= sb->s_blocksize ||
 234                     clu_base >= sbi->num_clusters) {
 235                         if (++map_i >= sbi->map_sectors) {
 236                                 clu_base = EXFAT_FIRST_CLUSTER;
 237                                 map_i = 0;
 238                         }
 239                         map_b = 0;
 240                 }
 241         }
 242
 243         return EXFAT_EOF_CLUSTER;
 244 }
 245
 246 int exfat_count_used_clusters(struct super_block *sb, unsigned int *ret_count)
 247 {
 248         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 249         unsigned int count = 0;
 250         unsigned int i, map_i = 0, map_b = 0;
 251         unsigned int total_clus = EXFAT_DATA_CLUSTER_COUNT(sbi);
 252         unsigned int last_mask = total_clus & BITS_PER_BYTE_MASK;
 253         unsigned char clu_bits;
 254         const unsigned char last_bit_mask[] = {0, 0b00000001, 0b00000011,
 255                 0b00000111, 0b00001111, 0b00011111, 0b00111111, 0b01111111};
 256
 257         total_clus &= ~last_mask;
 258         for (i = 0; i < total_clus; i += BITS_PER_BYTE) {
 259                 clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
 260                 count += used_bit[clu_bits];
 261                 if (++map_b >= (unsigned int)sb->s_blocksize) {
 262                         map_i++;
 263                         map_b = 0;
 264                 }
 265         }
 266
 267         if (last_mask) {
 268                 clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
 269                 clu_bits &= last_bit_mask[last_mask];
 270                 count += used_bit[clu_bits];
 271         }
 272
 273         *ret_count = count;
 274         return 0;
 275 }