fs/hfsplus/wrapper.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/hfsplus/wrapper.c
   4  *
   5  * Copyright (C) 2001
   6  * Brad Boyer (flar@allandria.com)
   7  * (C) 2003 Ardis Technologies <roman@ardistech.com>
   8  *
   9  * Handling of HFS wrappers around HFS+ volumes
  10  */
  11
  12 #include <linux/fs.h>
  13 #include <linux/blkdev.h>
  14 #include <linux/cdrom.h>
  15 #include <linux/genhd.h>
  16 #include <asm/unaligned.h>
  17
  18 #include "hfsplus_fs.h"
  19 #include "hfsplus_raw.h"
  20
  21 struct hfsplus_wd {
  22         u32 ablk_size;
  23         u16 ablk_start;
  24         u16 embed_start;
  25         u16 embed_count;
  26 };
  27
  28 /**
  29  * hfsplus_submit_bio - Perform block I/O
  30  * @sb: super block of volume for I/O
  31  * @sector: block to read or write, for blocks of HFSPLUS_SECTOR_SIZE bytes
  32  * @buf: buffer for I/O
  33  * @data: output pointer for location of requested data
  34  * @op: direction of I/O
  35  * @op_flags: request op flags
  36  *
  37  * The unit of I/O is hfsplus_min_io_size(sb), which may be bigger than
  38  * HFSPLUS_SECTOR_SIZE, and @buf must be sized accordingly. On reads
  39  * @data will return a pointer to the start of the requested sector,
  40  * which may not be the same location as @buf.
  41  *
  42  * If @sector is not aligned to the bdev logical block size it will
  43  * be rounded down. For writes this means that @buf should contain data
  44  * that starts at the rounded-down address. As long as the data was
  45  * read using hfsplus_submit_bio() and the same buffer is used things
  46  * will work correctly.
  47  */
  48 int hfsplus_submit_bio(struct super_block *sb, sector_t sector,
  49                        void *buf, void **data, int op, int op_flags)
  50 {
  51         struct bio *bio;
  52         int ret = 0;
  53         u64 io_size;
  54         loff_t start;
  55         int offset;
  56
  57         /*
  58          * Align sector to hardware sector size and find offset. We
  59          * assume that io_size is a power of two, which _should_
  60          * be true.
  61          */
  62         io_size = hfsplus_min_io_size(sb);
  63         start = (loff_t)sector << HFSPLUS_SECTOR_SHIFT;
  64         offset = start & (io_size - 1);
  65         sector &= ~((io_size >> HFSPLUS_SECTOR_SHIFT) - 1);
  66
  67         bio = bio_alloc(GFP_NOIO, 1);
  68         bio->bi_iter.bi_sector = sector;
  69         bio_set_dev(bio, sb->s_bdev);
  70         bio_set_op_attrs(bio, op, op_flags);
  71
  72         if (op != WRITE && data)
  73                 *data = (u8 *)buf + offset;
  74
  75         while (io_size > 0) {
  76                 unsigned int page_offset = offset_in_page(buf);
  77                 unsigned int len = min_t(unsigned int, PAGE_SIZE - page_offset,
  78                                          io_size);
  79
  80                 ret = bio_add_page(bio, virt_to_page(buf), len, page_offset);
  81                 if (ret != len) {
  82                         ret = -EIO;
  83                         goto out;
  84                 }
  85                 io_size -= len;
  86                 buf = (u8 *)buf + len;
  87         }
  88
  89         ret = submit_bio_wait(bio);
  90 out:
  91         bio_put(bio);
  92         return ret < 0 ? ret : 0;
  93 }
  94
  95 static int hfsplus_read_mdb(void *bufptr, struct hfsplus_wd *wd)
  96 {
  97         u32 extent;
  98         u16 attrib;
  99         __be16 sig;
 100
 101         sig = *(__be16 *)(bufptr + HFSP_WRAPOFF_EMBEDSIG);
 102         if (sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIG) &&
 103             sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIGX))
 104                 return 0;
 105
 106         attrib = be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ATTRIB));
 107         if (!(attrib & HFSP_WRAP_ATTRIB_SLOCK) ||
 108            !(attrib & HFSP_WRAP_ATTRIB_SPARED))
 109                 return 0;
 110
 111         wd->ablk_size =
 112                 be32_to_cpu(*(__be32 *)(bufptr + HFSP_WRAPOFF_ABLKSIZE));
 113         if (wd->ablk_size < HFSPLUS_SECTOR_SIZE)
 114                 return 0;
 115         if (wd->ablk_size % HFSPLUS_SECTOR_SIZE)
 116                 return 0;
 117         wd->ablk_start =
 118                 be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ABLKSTART));
 119
 120         extent = get_unaligned_be32(bufptr + HFSP_WRAPOFF_EMBEDEXT);
 121         wd->embed_start = (extent >> 16) & 0xFFFF;
 122         wd->embed_count = extent & 0xFFFF;
 123
 124         return 1;
 125 }
 126
 127 static int hfsplus_get_last_session(struct super_block *sb,
 128                                     sector_t *start, sector_t *size)
 129 {
 130         struct cdrom_multisession ms_info;
 131         struct cdrom_tocentry te;
 132         int res;
 133
 134         /* default values */
 135         *start = 0;
 136         *size = i_size_read(sb->s_bdev->bd_inode) >> 9;
 137
 138         if (HFSPLUS_SB(sb)->session >= 0) {
 139                 te.cdte_track = HFSPLUS_SB(sb)->session;
 140                 te.cdte_format = CDROM_LBA;
 141                 res = ioctl_by_bdev(sb->s_bdev,
 142                         CDROMREADTOCENTRY, (unsigned long)&te);
 143                 if (!res && (te.cdte_ctrl & CDROM_DATA_TRACK) == 4) {
 144                         *start = (sector_t)te.cdte_addr.lba << 2;
 145                         return 0;
 146                 }
 147                 pr_err("invalid session number or type of track\n");
 148                 return -EINVAL;
 149         }
 150         ms_info.addr_format = CDROM_LBA;
 151         res = ioctl_by_bdev(sb->s_bdev, CDROMMULTISESSION,
 152                 (unsigned long)&ms_info);
 153         if (!res && ms_info.xa_flag)
 154                 *start = (sector_t)ms_info.addr.lba << 2;
 155         return 0;
 156 }
 157
 158 /* Find the volume header and fill in some minimum bits in superblock */
 159 /* Takes in super block, returns true if good data read */
 160 int hfsplus_read_wrapper(struct super_block *sb)
 161 {
 162         struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
 163         struct hfsplus_wd wd;
 164         sector_t part_start, part_size;
 165         u32 blocksize;
 166         int error = 0;
 167
 168         error = -EINVAL;
 169         blocksize = sb_min_blocksize(sb, HFSPLUS_SECTOR_SIZE);
 170         if (!blocksize)
 171                 goto out;
 172
 173         if (hfsplus_get_last_session(sb, &part_start, &part_size))
 174                 goto out;
 175
 176         error = -ENOMEM;
 177         sbi->s_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
 178         if (!sbi->s_vhdr_buf)
 179                 goto out;
 180         sbi->s_backup_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
 181         if (!sbi->s_backup_vhdr_buf)
 182                 goto out_free_vhdr;
 183
 184 reread:
 185         error = hfsplus_submit_bio(sb, part_start + HFSPLUS_VOLHEAD_SECTOR,
 186                                    sbi->s_vhdr_buf, (void **)&sbi->s_vhdr,
 187                                    REQ_OP_READ, 0);
 188         if (error)
 189                 goto out_free_backup_vhdr;
 190
 191         error = -EINVAL;
 192         switch (sbi->s_vhdr->signature) {
 193         case cpu_to_be16(HFSPLUS_VOLHEAD_SIGX):
 194                 set_bit(HFSPLUS_SB_HFSX, &sbi->flags);
 195                 /*FALLTHRU*/
 196         case cpu_to_be16(HFSPLUS_VOLHEAD_SIG):
 197                 break;
 198         case cpu_to_be16(HFSP_WRAP_MAGIC):
 199                 if (!hfsplus_read_mdb(sbi->s_vhdr, &wd))
 200                         goto out_free_backup_vhdr;
 201                 wd.ablk_size >>= HFSPLUS_SECTOR_SHIFT;
 202                 part_start += (sector_t)wd.ablk_start +
 203                                (sector_t)wd.embed_start * wd.ablk_size;
 204                 part_size = (sector_t)wd.embed_count * wd.ablk_size;
 205                 goto reread;
 206         default:
 207                 /*
 208                  * Check for a partition block.
 209                  *
 210                  * (should do this only for cdrom/loop though)
 211                  */
 212                 if (hfs_part_find(sb, &part_start, &part_size))
 213                         goto out_free_backup_vhdr;
 214                 goto reread;
 215         }
 216
 217         error = hfsplus_submit_bio(sb, part_start + part_size - 2,
 218                                    sbi->s_backup_vhdr_buf,
 219                                    (void **)&sbi->s_backup_vhdr, REQ_OP_READ,
 220                                    0);
 221         if (error)
 222                 goto out_free_backup_vhdr;
 223
 224         error = -EINVAL;
 225         if (sbi->s_backup_vhdr->signature != sbi->s_vhdr->signature) {
 226                 pr_warn("invalid secondary volume header\n");
 227                 goto out_free_backup_vhdr;
 228         }
 229
 230         blocksize = be32_to_cpu(sbi->s_vhdr->blocksize);
 231
 232         /*
 233          * Block size must be at least as large as a sector and a multiple of 2.
 234          */
 235         if (blocksize < HFSPLUS_SECTOR_SIZE || ((blocksize - 1) & blocksize))
 236                 goto out_free_backup_vhdr;
 237         sbi->alloc_blksz = blocksize;
 238         sbi->alloc_blksz_shift = ilog2(blocksize);
 239         blocksize = min_t(u32, sbi->alloc_blksz, PAGE_SIZE);
 240
 241         /*
 242          * Align block size to block offset.
 243          */
 244         while (part_start & ((blocksize >> HFSPLUS_SECTOR_SHIFT) - 1))
 245                 blocksize >>= 1;
 246
 247         if (sb_set_blocksize(sb, blocksize) != blocksize) {
 248                 pr_err("unable to set blocksize to %u!\n", blocksize);
 249                 goto out_free_backup_vhdr;
 250         }
 251
 252         sbi->blockoffset =
 253                 part_start >> (sb->s_blocksize_bits - HFSPLUS_SECTOR_SHIFT);
 254         sbi->part_start = part_start;
 255         sbi->sect_count = part_size;
 256         sbi->fs_shift = sbi->alloc_blksz_shift - sb->s_blocksize_bits;
 257         return 0;
 258
 259 out_free_backup_vhdr:
 260         kfree(sbi->s_backup_vhdr_buf);
 261 out_free_vhdr:
 262         kfree(sbi->s_vhdr_buf);
 263 out:
 264         return error;
 265 }