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_msg(sb, KERN_ERR,
  62                                 "bogus allocation bitmap size(need : %u, cur : %lld)",
  63                                 need_map_size, map_size);
  64                 /*
  65                  * Only allowed when bogus allocation
  66                  * bitmap size is large
  67                  */
  68                 if (need_map_size > map_size)
  69                         return -EIO;
  70         }
  71         sbi->map_sectors = ((need_map_size - 1) >>
  72                         (sb->s_blocksize_bits)) + 1;
  73         sbi->vol_amap = kmalloc_array(sbi->map_sectors,
  74                                 sizeof(struct buffer_head *), GFP_KERNEL);
  75         if (!sbi->vol_amap)
  76                 return -ENOMEM;
  77
  78         sector = exfat_cluster_to_sector(sbi, sbi->map_clu);
  79         for (i = 0; i < sbi->map_sectors; i++) {
  80                 sbi->vol_amap[i] = sb_bread(sb, sector + i);
  81                 if (!sbi->vol_amap[i]) {
  82                         /* release all buffers and free vol_amap */
  83                         int j = 0;
  84
  85                         while (j < i)
  86                                 brelse(sbi->vol_amap[j++]);
  87
  88                         kfree(sbi->vol_amap);
  89                         sbi->vol_amap = NULL;
  90                         return -EIO;
  91                 }
  92         }
  93
  94         sbi->pbr_bh = NULL;
  95         return 0;
  96 }
  97
  98 int exfat_load_bitmap(struct super_block *sb)
  99 {
 100         unsigned int i, type;
 101         struct exfat_chain clu;
 102         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 103
 104         exfat_chain_set(&clu, sbi->root_dir, 0, ALLOC_FAT_CHAIN);
 105         while (clu.dir != EXFAT_EOF_CLUSTER) {
 106                 for (i = 0; i < sbi->dentries_per_clu; i++) {
 107                         struct exfat_dentry *ep;
 108                         struct buffer_head *bh;
 109
 110                         ep = exfat_get_dentry(sb, &clu, i, &bh, NULL);
 111                         if (!ep)
 112                                 return -EIO;
 113
 114                         type = exfat_get_entry_type(ep);
 115                         if (type == TYPE_UNUSED)
 116                                 break;
 117                         if (type != TYPE_BITMAP)
 118                                 continue;
 119                         if (ep->dentry.bitmap.flags == 0x0) {
 120                                 int err;
 121
 122                                 err = exfat_allocate_bitmap(sb, ep);
 123                                 brelse(bh);
 124                                 return err;
 125                         }
 126                         brelse(bh);
 127                 }
 128
 129                 if (exfat_get_next_cluster(sb, &clu.dir))
 130                         return -EIO;
 131         }
 132
 133         return -EINVAL;
 134 }
 135
 136 void exfat_free_bitmap(struct exfat_sb_info *sbi)
 137 {
 138         int i;
 139
 140         brelse(sbi->pbr_bh);
 141
 142         for (i = 0; i < sbi->map_sectors; i++)
 143                 __brelse(sbi->vol_amap[i]);
 144
 145         kfree(sbi->vol_amap);
 146 }
 147
 148 /*
 149  * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
 150  * the cluster heap.
 151  */
 152 int exfat_set_bitmap(struct inode *inode, unsigned int clu)
 153 {
 154         int i, b;
 155         unsigned int ent_idx;
 156         struct super_block *sb = inode->i_sb;
 157         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 158
 159         WARN_ON(clu < EXFAT_FIRST_CLUSTER);
 160         ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
 161         i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
 162         b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
 163
 164         set_bit_le(b, sbi->vol_amap[i]->b_data);
 165         exfat_update_bh(sb, sbi->vol_amap[i], IS_DIRSYNC(inode));
 166         return 0;
 167 }
 168
 169 /*
 170  * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
 171  * the cluster heap.
 172  */
 173 void exfat_clear_bitmap(struct inode *inode, unsigned int clu)
 174 {
 175         int i, b;
 176         unsigned int ent_idx;
 177         struct super_block *sb = inode->i_sb;
 178         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 179         struct exfat_mount_options *opts = &sbi->options;
 180
 181         WARN_ON(clu < EXFAT_FIRST_CLUSTER);
 182         ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
 183         i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
 184         b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
 185
 186         clear_bit_le(b, sbi->vol_amap[i]->b_data);
 187         exfat_update_bh(sb, sbi->vol_amap[i], IS_DIRSYNC(inode));
 188
 189         if (opts->discard) {
 190                 int ret_discard;
 191
 192                 ret_discard = sb_issue_discard(sb,
 193                         exfat_cluster_to_sector(sbi, clu +
 194                                                 EXFAT_RESERVED_CLUSTERS),
 195                         (1 << sbi->sect_per_clus_bits), GFP_NOFS, 0);
 196
 197                 if (ret_discard == -EOPNOTSUPP) {
 198                         exfat_msg(sb, KERN_ERR,
 199                                 "discard not supported by device, disabling");
 200                         opts->discard = 0;
 201                 }
 202         }
 203 }
 204
 205 /*
 206  * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
 207  * the cluster heap.
 208  */
 209 unsigned int exfat_find_free_bitmap(struct super_block *sb, unsigned int clu)
 210 {
 211         unsigned int i, map_i, map_b, ent_idx;
 212         unsigned int clu_base, clu_free;
 213         unsigned char k, clu_mask;
 214         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 215
 216         WARN_ON(clu < EXFAT_FIRST_CLUSTER);
 217         ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
 218         clu_base = BITMAP_ENT_TO_CLUSTER(ent_idx & ~(BITS_PER_BYTE_MASK));
 219         clu_mask = IGNORED_BITS_REMAINED(clu, clu_base);
 220
 221         map_i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
 222         map_b = BITMAP_OFFSET_BYTE_IN_SECTOR(sb, ent_idx);
 223
 224         for (i = EXFAT_FIRST_CLUSTER; i < sbi->num_clusters;
 225              i += BITS_PER_BYTE) {
 226                 k = *(sbi->vol_amap[map_i]->b_data + map_b);
 227                 if (clu_mask > 0) {
 228                         k |= clu_mask;
 229                         clu_mask = 0;
 230                 }
 231                 if (k < 0xFF) {
 232                         clu_free = clu_base + free_bit[k];
 233                         if (clu_free < sbi->num_clusters)
 234                                 return clu_free;
 235                 }
 236                 clu_base += BITS_PER_BYTE;
 237
 238                 if (++map_b >= sb->s_blocksize ||
 239                     clu_base >= sbi->num_clusters) {
 240                         if (++map_i >= sbi->map_sectors) {
 241                                 clu_base = EXFAT_FIRST_CLUSTER;
 242                                 map_i = 0;
 243                         }
 244                         map_b = 0;
 245                 }
 246         }
 247
 248         return EXFAT_EOF_CLUSTER;
 249 }
 250
 251 int exfat_count_used_clusters(struct super_block *sb, unsigned int *ret_count)
 252 {
 253         struct exfat_sb_info *sbi = EXFAT_SB(sb);
 254         unsigned int count = 0;
 255         unsigned int i, map_i = 0, map_b = 0;
 256         unsigned int total_clus = EXFAT_DATA_CLUSTER_COUNT(sbi);
 257         unsigned int last_mask = total_clus & BITS_PER_BYTE_MASK;
 258         unsigned char clu_bits;
 259         const unsigned char last_bit_mask[] = {0, 0b00000001, 0b00000011,
 260                 0b00000111, 0b00001111, 0b00011111, 0b00111111, 0b01111111};
 261
 262         total_clus &= ~last_mask;
 263         for (i = 0; i < total_clus; i += BITS_PER_BYTE) {
 264                 clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
 265                 count += used_bit[clu_bits];
 266                 if (++map_b >= (unsigned int)sb->s_blocksize) {
 267                         map_i++;
 268                         map_b = 0;
 269                 }
 270         }
 271
 272         if (last_mask) {
 273                 clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
 274                 clu_bits &= last_bit_mask[last_mask];
 275                 count += used_bit[clu_bits];
 276         }
 277
 278         *ret_count = count;
 279         return 0;
 280 }