fs/hfsplus/wrapper.c

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