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 static void hfsplus_end_io_sync(struct bio *bio, int err)
  28 {
  29         if (err)
  30                 clear_bit(BIO_UPTODATE, &bio->bi_flags);
  31         complete(bio->bi_private);
  32 }
  33
  34 int hfsplus_submit_bio(struct block_device *bdev, sector_t sector,
  35                 void *data, int rw)
  36 {
  37         DECLARE_COMPLETION_ONSTACK(wait);
  38         struct bio *bio;
  39         int ret = 0;
  40
  41         bio = bio_alloc(GFP_NOIO, 1);
  42         bio->bi_sector = sector;
  43         bio->bi_bdev = bdev;
  44         bio->bi_end_io = hfsplus_end_io_sync;
  45         bio->bi_private = &wait;
  46
  47         /*
  48          * We always submit one sector at a time, so bio_add_page must not fail.
  49          */
  50         if (bio_add_page(bio, virt_to_page(data), HFSPLUS_SECTOR_SIZE,
  51                          offset_in_page(data)) != HFSPLUS_SECTOR_SIZE)
  52                 BUG();
  53
  54         submit_bio(rw, bio);
  55         wait_for_completion(&wait);
  56
  57         if (!bio_flagged(bio, BIO_UPTODATE))
  58                 ret = -EIO;
  59
  60         bio_put(bio);
  61         return ret;
  62 }
  63
  64 static int hfsplus_read_mdb(void *bufptr, struct hfsplus_wd *wd)
  65 {
  66         u32 extent;
  67         u16 attrib;
  68         __be16 sig;
  69
  70         sig = *(__be16 *)(bufptr + HFSP_WRAPOFF_EMBEDSIG);
  71         if (sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIG) &&
  72             sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIGX))
  73                 return 0;
  74
  75         attrib = be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ATTRIB));
  76         if (!(attrib & HFSP_WRAP_ATTRIB_SLOCK) ||
  77            !(attrib & HFSP_WRAP_ATTRIB_SPARED))
  78                 return 0;
  79
  80         wd->ablk_size =
  81                 be32_to_cpu(*(__be32 *)(bufptr + HFSP_WRAPOFF_ABLKSIZE));
  82         if (wd->ablk_size < HFSPLUS_SECTOR_SIZE)
  83                 return 0;
  84         if (wd->ablk_size % HFSPLUS_SECTOR_SIZE)
  85                 return 0;
  86         wd->ablk_start =
  87                 be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ABLKSTART));
  88
  89         extent = get_unaligned_be32(bufptr + HFSP_WRAPOFF_EMBEDEXT);
  90         wd->embed_start = (extent >> 16) & 0xFFFF;
  91         wd->embed_count = extent & 0xFFFF;
  92
  93         return 1;
  94 }
  95
  96 static int hfsplus_get_last_session(struct super_block *sb,
  97                                     sector_t *start, sector_t *size)
  98 {
  99         struct cdrom_multisession ms_info;
 100         struct cdrom_tocentry te;
 101         int res;
 102
 103         /* default values */
 104         *start = 0;
 105         *size = sb->s_bdev->bd_inode->i_size >> 9;
 106
 107         if (HFSPLUS_SB(sb)->session >= 0) {
 108                 te.cdte_track = HFSPLUS_SB(sb)->session;
 109                 te.cdte_format = CDROM_LBA;
 110                 res = ioctl_by_bdev(sb->s_bdev,
 111                         CDROMREADTOCENTRY, (unsigned long)&te);
 112                 if (!res && (te.cdte_ctrl & CDROM_DATA_TRACK) == 4) {
 113                         *start = (sector_t)te.cdte_addr.lba << 2;
 114                         return 0;
 115                 }
 116                 printk(KERN_ERR "hfs: invalid session number or type of track\n");
 117                 return -EINVAL;
 118         }
 119         ms_info.addr_format = CDROM_LBA;
 120         res = ioctl_by_bdev(sb->s_bdev, CDROMMULTISESSION,
 121                 (unsigned long)&ms_info);
 122         if (!res && ms_info.xa_flag)
 123                 *start = (sector_t)ms_info.addr.lba << 2;
 124         return 0;
 125 }
 126
 127 /* Find the volume header and fill in some minimum bits in superblock */
 128 /* Takes in super block, returns true if good data read */
 129 int hfsplus_read_wrapper(struct super_block *sb)
 130 {
 131         struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
 132         struct hfsplus_wd wd;
 133         sector_t part_start, part_size;
 134         u32 blocksize;
 135         int error = 0;
 136
 137         error = -EINVAL;
 138         blocksize = sb_min_blocksize(sb, HFSPLUS_SECTOR_SIZE);
 139         if (!blocksize)
 140                 goto out;
 141
 142         if (hfsplus_get_last_session(sb, &part_start, &part_size))
 143                 goto out;
 144
 145         error = -ENOMEM;
 146         sbi->s_vhdr = kmalloc(HFSPLUS_SECTOR_SIZE, GFP_KERNEL);
 147         if (!sbi->s_vhdr)
 148                 goto out;
 149         sbi->s_backup_vhdr = kmalloc(HFSPLUS_SECTOR_SIZE, GFP_KERNEL);
 150         if (!sbi->s_backup_vhdr)
 151                 goto out_free_vhdr;
 152
 153 reread:
 154         error = hfsplus_submit_bio(sb->s_bdev,
 155                                    part_start + HFSPLUS_VOLHEAD_SECTOR,
 156                                    sbi->s_vhdr, READ);
 157         if (error)
 158                 goto out_free_backup_vhdr;
 159
 160         error = -EINVAL;
 161         switch (sbi->s_vhdr->signature) {
 162         case cpu_to_be16(HFSPLUS_VOLHEAD_SIGX):
 163                 set_bit(HFSPLUS_SB_HFSX, &sbi->flags);
 164                 /*FALLTHRU*/
 165         case cpu_to_be16(HFSPLUS_VOLHEAD_SIG):
 166                 break;
 167         case cpu_to_be16(HFSP_WRAP_MAGIC):
 168                 if (!hfsplus_read_mdb(sbi->s_vhdr, &wd))
 169                         goto out_free_backup_vhdr;
 170                 wd.ablk_size >>= HFSPLUS_SECTOR_SHIFT;
 171                 part_start += (sector_t)wd.ablk_start +
 172                                (sector_t)wd.embed_start * wd.ablk_size;
 173                 part_size = (sector_t)wd.embed_count * wd.ablk_size;
 174                 goto reread;
 175         default:
 176                 /*
 177                  * Check for a partition block.
 178                  *
 179                  * (should do this only for cdrom/loop though)
 180                  */
 181                 if (hfs_part_find(sb, &part_start, &part_size))
 182                         goto out_free_backup_vhdr;
 183                 goto reread;
 184         }
 185
 186         error = hfsplus_submit_bio(sb->s_bdev,
 187                                    part_start + part_size - 2,
 188                                    sbi->s_backup_vhdr, READ);
 189         if (error)
 190                 goto out_free_backup_vhdr;
 191
 192         error = -EINVAL;
 193         if (sbi->s_backup_vhdr->signature != sbi->s_vhdr->signature) {
 194                 printk(KERN_WARNING
 195                         "hfs: invalid secondary volume header\n");
 196                 goto out_free_backup_vhdr;
 197         }
 198
 199         blocksize = be32_to_cpu(sbi->s_vhdr->blocksize);
 200
 201         /*
 202          * Block size must be at least as large as a sector and a multiple of 2.
 203          */
 204         if (blocksize < HFSPLUS_SECTOR_SIZE || ((blocksize - 1) & blocksize))
 205                 goto out_free_backup_vhdr;
 206         sbi->alloc_blksz = blocksize;
 207         sbi->alloc_blksz_shift = 0;
 208         while ((blocksize >>= 1) != 0)
 209                 sbi->alloc_blksz_shift++;
 210         blocksize = min(sbi->alloc_blksz, (u32)PAGE_SIZE);
 211
 212         /*
 213          * Align block size to block offset.
 214          */
 215         while (part_start & ((blocksize >> HFSPLUS_SECTOR_SHIFT) - 1))
 216                 blocksize >>= 1;
 217
 218         if (sb_set_blocksize(sb, blocksize) != blocksize) {
 219                 printk(KERN_ERR "hfs: unable to set blocksize to %u!\n",
 220                         blocksize);
 221                 goto out_free_backup_vhdr;
 222         }
 223
 224         sbi->blockoffset =
 225                 part_start >> (sb->s_blocksize_bits - HFSPLUS_SECTOR_SHIFT);
 226         sbi->part_start = part_start;
 227         sbi->sect_count = part_size;
 228         sbi->fs_shift = sbi->alloc_blksz_shift - sb->s_blocksize_bits;
 229         return 0;
 230
 231 out_free_backup_vhdr:
 232         kfree(sbi->s_backup_vhdr);
 233 out_free_vhdr:
 234         kfree(sbi->s_vhdr);
 235 out:
 236         return error;
 237 }