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 /*
  35  * hfsplus_submit_bio - Perfrom block I/O
  36  * @sb: super block of volume for I/O
  37  * @sector: block to read or write, for blocks of HFSPLUS_SECTOR_SIZE bytes
  38  * @buf: buffer for I/O
  39  * @data: output pointer for location of requested data
  40  * @rw: direction of I/O
  41  *
  42  * The unit of I/O is hfsplus_min_io_size(sb), which may be bigger than
  43  * HFSPLUS_SECTOR_SIZE, and @buf must be sized accordingly. On reads
  44  * @data will return a pointer to the start of the requested sector,
  45  * which may not be the same location as @buf.
  46  *
  47  * If @sector is not aligned to the bdev logical block size it will
  48  * be rounded down. For writes this means that @buf should contain data
  49  * that starts at the rounded-down address. As long as the data was
  50  * read using hfsplus_submit_bio() and the same buffer is used things
  51  * will work correctly.
  52  */
  53 int hfsplus_submit_bio(struct super_block *sb, sector_t sector,
  54                 void *buf, void **data, int rw)
  55 {
  56         DECLARE_COMPLETION_ONSTACK(wait);
  57         struct bio *bio;
  58         int ret = 0;
  59         unsigned int io_size;
  60         loff_t start;
  61         int offset;
  62
  63         /*
  64          * Align sector to hardware sector size and find offset. We
  65          * assume that io_size is a power of two, which _should_
  66          * be true.
  67          */
  68         io_size = hfsplus_min_io_size(sb);
  69         start = (loff_t)sector << HFSPLUS_SECTOR_SHIFT;
  70         offset = start & (io_size - 1);
  71         sector &= ~((io_size >> HFSPLUS_SECTOR_SHIFT) - 1);
  72
  73         bio = bio_alloc(GFP_NOIO, 1);
  74         bio->bi_sector = sector;
  75         bio->bi_bdev = sb->s_bdev;
  76         bio->bi_end_io = hfsplus_end_io_sync;
  77         bio->bi_private = &wait;
  78
  79         if (!(rw & WRITE) && data)
  80                 *data = (u8 *)buf + offset;
  81
  82         while (io_size > 0) {
  83                 unsigned int page_offset = offset_in_page(buf);
  84                 unsigned int len = min_t(unsigned int, PAGE_SIZE - page_offset,
  85                                          io_size);
  86
  87                 ret = bio_add_page(bio, virt_to_page(buf), len, page_offset);
  88                 if (ret != len) {
  89                         ret = -EIO;
  90                         goto out;
  91                 }
  92                 io_size -= len;
  93                 buf = (u8 *)buf + len;
  94         }
  95
  96         submit_bio(rw, bio);
  97         wait_for_completion(&wait);
  98
  99         if (!bio_flagged(bio, BIO_UPTODATE))
 100                 ret = -EIO;
 101
 102 out:
 103         bio_put(bio);
 104         return ret < 0 ? ret : 0;
 105 }
 106
 107 static int hfsplus_read_mdb(void *bufptr, struct hfsplus_wd *wd)
 108 {
 109         u32 extent;
 110         u16 attrib;
 111         __be16 sig;
 112
 113         sig = *(__be16 *)(bufptr + HFSP_WRAPOFF_EMBEDSIG);
 114         if (sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIG) &&
 115             sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIGX))
 116                 return 0;
 117
 118         attrib = be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ATTRIB));
 119         if (!(attrib & HFSP_WRAP_ATTRIB_SLOCK) ||
 120            !(attrib & HFSP_WRAP_ATTRIB_SPARED))
 121                 return 0;
 122
 123         wd->ablk_size =
 124                 be32_to_cpu(*(__be32 *)(bufptr + HFSP_WRAPOFF_ABLKSIZE));
 125         if (wd->ablk_size < HFSPLUS_SECTOR_SIZE)
 126                 return 0;
 127         if (wd->ablk_size % HFSPLUS_SECTOR_SIZE)
 128                 return 0;
 129         wd->ablk_start =
 130                 be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ABLKSTART));
 131
 132         extent = get_unaligned_be32(bufptr + HFSP_WRAPOFF_EMBEDEXT);
 133         wd->embed_start = (extent >> 16) & 0xFFFF;
 134         wd->embed_count = extent & 0xFFFF;
 135
 136         return 1;
 137 }
 138
 139 static int hfsplus_get_last_session(struct super_block *sb,
 140                                     sector_t *start, sector_t *size)
 141 {
 142         struct cdrom_multisession ms_info;
 143         struct cdrom_tocentry te;
 144         int res;
 145
 146         /* default values */
 147         *start = 0;
 148         *size = sb->s_bdev->bd_inode->i_size >> 9;
 149
 150         if (HFSPLUS_SB(sb)->session >= 0) {
 151                 te.cdte_track = HFSPLUS_SB(sb)->session;
 152                 te.cdte_format = CDROM_LBA;
 153                 res = ioctl_by_bdev(sb->s_bdev,
 154                         CDROMREADTOCENTRY, (unsigned long)&te);
 155                 if (!res && (te.cdte_ctrl & CDROM_DATA_TRACK) == 4) {
 156                         *start = (sector_t)te.cdte_addr.lba << 2;
 157                         return 0;
 158                 }
 159                 printk(KERN_ERR "hfs: invalid session number or type of track\n");
 160                 return -EINVAL;
 161         }
 162         ms_info.addr_format = CDROM_LBA;
 163         res = ioctl_by_bdev(sb->s_bdev, CDROMMULTISESSION,
 164                 (unsigned long)&ms_info);
 165         if (!res && ms_info.xa_flag)
 166                 *start = (sector_t)ms_info.addr.lba << 2;
 167         return 0;
 168 }
 169
 170 /* Find the volume header and fill in some minimum bits in superblock */
 171 /* Takes in super block, returns true if good data read */
 172 int hfsplus_read_wrapper(struct super_block *sb)
 173 {
 174         struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
 175         struct hfsplus_wd wd;
 176         sector_t part_start, part_size;
 177         u32 blocksize;
 178         int error = 0;
 179
 180         error = -EINVAL;
 181         blocksize = sb_min_blocksize(sb, HFSPLUS_SECTOR_SIZE);
 182         if (!blocksize)
 183                 goto out;
 184
 185         if (hfsplus_get_last_session(sb, &part_start, &part_size))
 186                 goto out;
 187
 188         error = -ENOMEM;
 189         sbi->s_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
 190         if (!sbi->s_vhdr_buf)
 191                 goto out;
 192         sbi->s_backup_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
 193         if (!sbi->s_backup_vhdr_buf)
 194                 goto out_free_vhdr;
 195
 196 reread:
 197         error = hfsplus_submit_bio(sb, part_start + HFSPLUS_VOLHEAD_SECTOR,
 198                                    sbi->s_vhdr_buf, (void **)&sbi->s_vhdr,
 199                                    READ);
 200         if (error)
 201                 goto out_free_backup_vhdr;
 202
 203         error = -EINVAL;
 204         switch (sbi->s_vhdr->signature) {
 205         case cpu_to_be16(HFSPLUS_VOLHEAD_SIGX):
 206                 set_bit(HFSPLUS_SB_HFSX, &sbi->flags);
 207                 /*FALLTHRU*/
 208         case cpu_to_be16(HFSPLUS_VOLHEAD_SIG):
 209                 break;
 210         case cpu_to_be16(HFSP_WRAP_MAGIC):
 211                 if (!hfsplus_read_mdb(sbi->s_vhdr, &wd))
 212                         goto out_free_backup_vhdr;
 213                 wd.ablk_size >>= HFSPLUS_SECTOR_SHIFT;
 214                 part_start += (sector_t)wd.ablk_start +
 215                                (sector_t)wd.embed_start * wd.ablk_size;
 216                 part_size = (sector_t)wd.embed_count * wd.ablk_size;
 217                 goto reread;
 218         default:
 219                 /*
 220                  * Check for a partition block.
 221                  *
 222                  * (should do this only for cdrom/loop though)
 223                  */
 224                 if (hfs_part_find(sb, &part_start, &part_size))
 225                         goto out_free_backup_vhdr;
 226                 goto reread;
 227         }
 228
 229         error = hfsplus_submit_bio(sb, part_start + part_size - 2,
 230                                    sbi->s_backup_vhdr_buf,
 231                                    (void **)&sbi->s_backup_vhdr, READ);
 232         if (error)
 233                 goto out_free_backup_vhdr;
 234
 235         error = -EINVAL;
 236         if (sbi->s_backup_vhdr->signature != sbi->s_vhdr->signature) {
 237                 printk(KERN_WARNING
 238                         "hfs: invalid secondary volume header\n");
 239                 goto out_free_backup_vhdr;
 240         }
 241
 242         blocksize = be32_to_cpu(sbi->s_vhdr->blocksize);
 243
 244         /*
 245          * Block size must be at least as large as a sector and a multiple of 2.
 246          */
 247         if (blocksize < HFSPLUS_SECTOR_SIZE || ((blocksize - 1) & blocksize))
 248                 goto out_free_backup_vhdr;
 249         sbi->alloc_blksz = blocksize;
 250         sbi->alloc_blksz_shift = 0;
 251         while ((blocksize >>= 1) != 0)
 252                 sbi->alloc_blksz_shift++;
 253         blocksize = min(sbi->alloc_blksz, (u32)PAGE_SIZE);
 254
 255         /*
 256          * Align block size to block offset.
 257          */
 258         while (part_start & ((blocksize >> HFSPLUS_SECTOR_SHIFT) - 1))
 259                 blocksize >>= 1;
 260
 261         if (sb_set_blocksize(sb, blocksize) != blocksize) {
 262                 printk(KERN_ERR "hfs: unable to set blocksize to %u!\n",
 263                         blocksize);
 264                 goto out_free_backup_vhdr;
 265         }
 266
 267         sbi->blockoffset =
 268                 part_start >> (sb->s_blocksize_bits - HFSPLUS_SECTOR_SHIFT);
 269         sbi->part_start = part_start;
 270         sbi->sect_count = part_size;
 271         sbi->fs_shift = sbi->alloc_blksz_shift - sb->s_blocksize_bits;
 272         return 0;
 273
 274 out_free_backup_vhdr:
 275         kfree(sbi->s_backup_vhdr_buf);
 276 out_free_vhdr:
 277         kfree(sbi->s_vhdr_buf);
 278 out:
 279         return error;
 280 }