LXR linux/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
  13static 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
  29static 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 */
  48static 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
  96int 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
 134void 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
 144int exfat_set_bitmap(struct inode *inode, unsigned int clu, bool sync)
 145{
 146        int i, b;
 147        unsigned int ent_idx;
 148        struct super_block *sb = inode->i_sb;
 149        struct exfat_sb_info *sbi = EXFAT_SB(sb);
 150
 151        WARN_ON(clu < EXFAT_FIRST_CLUSTER);
 152        ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
 153        i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
 154        b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
 155
 156        set_bit_le(b, sbi->vol_amap[i]->b_data);
 157        exfat_update_bh(sbi->vol_amap[i], sync);
 158        return 0;
 159}
 160
 161void exfat_clear_bitmap(struct inode *inode, unsigned int clu, bool sync)
 162{
 163        int i, b;
 164        unsigned int ent_idx;
 165        struct super_block *sb = inode->i_sb;
 166        struct exfat_sb_info *sbi = EXFAT_SB(sb);
 167        struct exfat_mount_options *opts = &sbi->options;
 168
 169        WARN_ON(clu < EXFAT_FIRST_CLUSTER);
 170        ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
 171        i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
 172        b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
 173
 174        clear_bit_le(b, sbi->vol_amap[i]->b_data);
 175        exfat_update_bh(sbi->vol_amap[i], sync);
 176
 177        if (opts->discard) {
 178                int ret_discard;
 179
 180                ret_discard = sb_issue_discard(sb,
 181                        exfat_cluster_to_sector(sbi, clu),
 182                        (1 << sbi->sect_per_clus_bits), GFP_NOFS, 0);
 183
 184                if (ret_discard == -EOPNOTSUPP) {
 185                        exfat_err(sb, "discard not supported by device, disabling");
 186                        opts->discard = 0;
 187                }
 188        }
 189}
 190
 191/*
 192 * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
 193 * the cluster heap.
 194 */
 195unsigned int exfat_find_free_bitmap(struct super_block *sb, unsigned int clu)
 196{
 197        unsigned int i, map_i, map_b, ent_idx;
 198        unsigned int clu_base, clu_free;
 199        unsigned char k, clu_mask;
 200        struct exfat_sb_info *sbi = EXFAT_SB(sb);
 201
 202        WARN_ON(clu < EXFAT_FIRST_CLUSTER);
 203        ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
 204        clu_base = BITMAP_ENT_TO_CLUSTER(ent_idx & ~(BITS_PER_BYTE_MASK));
 205        clu_mask = IGNORED_BITS_REMAINED(clu, clu_base);
 206
 207        map_i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
 208        map_b = BITMAP_OFFSET_BYTE_IN_SECTOR(sb, ent_idx);
 209
 210        for (i = EXFAT_FIRST_CLUSTER; i < sbi->num_clusters;
 211             i += BITS_PER_BYTE) {
 212                k = *(sbi->vol_amap[map_i]->b_data + map_b);
 213                if (clu_mask > 0) {
 214                        k |= clu_mask;
 215                        clu_mask = 0;
 216                }
 217                if (k < 0xFF) {
 218                        clu_free = clu_base + free_bit[k];
 219                        if (clu_free < sbi->num_clusters)
 220                                return clu_free;
 221                }
 222                clu_base += BITS_PER_BYTE;
 223
 224                if (++map_b >= sb->s_blocksize ||
 225                    clu_base >= sbi->num_clusters) {
 226                        if (++map_i >= sbi->map_sectors) {
 227                                clu_base = EXFAT_FIRST_CLUSTER;
 228                                map_i = 0;
 229                        }
 230                        map_b = 0;
 231                }
 232        }
 233
 234        return EXFAT_EOF_CLUSTER;
 235}
 236
 237int exfat_count_used_clusters(struct super_block *sb, unsigned int *ret_count)
 238{
 239        struct exfat_sb_info *sbi = EXFAT_SB(sb);
 240        unsigned int count = 0;
 241        unsigned int i, map_i = 0, map_b = 0;
 242        unsigned int total_clus = EXFAT_DATA_CLUSTER_COUNT(sbi);
 243        unsigned int last_mask = total_clus & BITS_PER_BYTE_MASK;
 244        unsigned char clu_bits;
 245        const unsigned char last_bit_mask[] = {0, 0b00000001, 0b00000011,
 246                0b00000111, 0b00001111, 0b00011111, 0b00111111, 0b01111111};
 247
 248        total_clus &= ~last_mask;
 249        for (i = 0; i < total_clus; i += BITS_PER_BYTE) {
 250                clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
 251                count += used_bit[clu_bits];
 252                if (++map_b >= (unsigned int)sb->s_blocksize) {
 253                        map_i++;
 254                        map_b = 0;
 255                }
 256        }
 257
 258        if (last_mask) {
 259                clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
 260                clu_bits &= last_bit_mask[last_mask];
 261                count += used_bit[clu_bits];
 262        }
 263
 264        *ret_count = count;
 265        return 0;
 266}
 267
 268int exfat_trim_fs(struct inode *inode, struct fstrim_range *range)
 269{
 270        unsigned int trim_begin, trim_end, count, next_free_clu;
 271        u64 clu_start, clu_end, trim_minlen, trimmed_total = 0;
 272        struct super_block *sb = inode->i_sb;
 273        struct exfat_sb_info *sbi = EXFAT_SB(sb);
 274        int err = 0;
 275
 276        clu_start = max_t(u64, range->start >> sbi->cluster_size_bits,
 277                                EXFAT_FIRST_CLUSTER);
 278        clu_end = clu_start + (range->len >> sbi->cluster_size_bits) - 1;
 279        trim_minlen = range->minlen >> sbi->cluster_size_bits;
 280
 281        if (clu_start >= sbi->num_clusters || range->len < sbi->cluster_size)
 282                return -EINVAL;
 283
 284        if (clu_end >= sbi->num_clusters)
 285                clu_end = sbi->num_clusters - 1;
 286
 287        mutex_lock(&sbi->bitmap_lock);
 288
 289        trim_begin = trim_end = exfat_find_free_bitmap(sb, clu_start);
 290        if (trim_begin == EXFAT_EOF_CLUSTER)
 291                goto unlock;
 292
 293        next_free_clu = exfat_find_free_bitmap(sb, trim_end + 1);
 294        if (next_free_clu == EXFAT_EOF_CLUSTER)
 295                goto unlock;
 296
 297        do {
 298                if (next_free_clu == trim_end + 1) {
 299                        /* extend trim range for continuous free cluster */
 300                        trim_end++;
 301                } else {
 302                        /* trim current range if it's larger than trim_minlen */
 303                        count = trim_end - trim_begin + 1;
 304                        if (count >= trim_minlen) {
 305                                err = sb_issue_discard(sb,
 306                                        exfat_cluster_to_sector(sbi, trim_begin),
 307                                        count * sbi->sect_per_clus, GFP_NOFS, 0);
 308                                if (err)
 309                                        goto unlock;
 310
 311                                trimmed_total += count;
 312                        }
 313
 314                        /* set next start point of the free hole */
 315                        trim_begin = trim_end = next_free_clu;
 316                }
 317
 318                if (next_free_clu >= clu_end)
 319                        break;
 320
 321                if (fatal_signal_pending(current)) {
 322                        err = -ERESTARTSYS;
 323                        goto unlock;
 324                }
 325
 326                next_free_clu = exfat_find_free_bitmap(sb, next_free_clu + 1);
 327        } while (next_free_clu != EXFAT_EOF_CLUSTER &&
 328                        next_free_clu > trim_end);
 329
 330        /* try to trim remainder */
 331        count = trim_end - trim_begin + 1;
 332        if (count >= trim_minlen) {
 333                err = sb_issue_discard(sb, exfat_cluster_to_sector(sbi, trim_begin),
 334                        count * sbi->sect_per_clus, GFP_NOFS, 0);
 335                if (err)
 336                        goto unlock;
 337
 338                trimmed_total += count;
 339        }
 340
 341unlock:
 342        mutex_unlock(&sbi->bitmap_lock);
 343        range->len = trimmed_total << sbi->cluster_size_bits;
 344
 345        return err;
 346}
 347