linux/fs/hfsplus/wrapper.c
<<
>>
Prefs
   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
  20struct hfsplus_wd {
  21        u32 ablk_size;
  22        u16 ablk_start;
  23        u16 embed_start;
  24        u16 embed_count;
  25};
  26
  27static 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 */
  53int 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        u64 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
 102out:
 103        bio_put(bio);
 104        return ret < 0 ? ret : 0;
 105}
 106
 107static 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
 139static 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                pr_err("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 */
 172int 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
 196reread:
 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                pr_warn("invalid secondary volume header\n");
 238                goto out_free_backup_vhdr;
 239        }
 240
 241        blocksize = be32_to_cpu(sbi->s_vhdr->blocksize);
 242
 243        /*
 244         * Block size must be at least as large as a sector and a multiple of 2.
 245         */
 246        if (blocksize < HFSPLUS_SECTOR_SIZE || ((blocksize - 1) & blocksize))
 247                goto out_free_backup_vhdr;
 248        sbi->alloc_blksz = blocksize;
 249        sbi->alloc_blksz_shift = 0;
 250        while ((blocksize >>= 1) != 0)
 251                sbi->alloc_blksz_shift++;
 252        blocksize = min(sbi->alloc_blksz, (u32)PAGE_SIZE);
 253
 254        /*
 255         * Align block size to block offset.
 256         */
 257        while (part_start & ((blocksize >> HFSPLUS_SECTOR_SHIFT) - 1))
 258                blocksize >>= 1;
 259
 260        if (sb_set_blocksize(sb, blocksize) != blocksize) {
 261                pr_err("unable to set blocksize to %u!\n", blocksize);
 262                goto out_free_backup_vhdr;
 263        }
 264
 265        sbi->blockoffset =
 266                part_start >> (sb->s_blocksize_bits - HFSPLUS_SECTOR_SHIFT);
 267        sbi->part_start = part_start;
 268        sbi->sect_count = part_size;
 269        sbi->fs_shift = sbi->alloc_blksz_shift - sb->s_blocksize_bits;
 270        return 0;
 271
 272out_free_backup_vhdr:
 273        kfree(sbi->s_backup_vhdr_buf);
 274out_free_vhdr:
 275        kfree(sbi->s_vhdr_buf);
 276out:
 277        return error;
 278}
 279
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.