wrapper.c

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/*
 *  linux/fs/hfsplus/wrapper.c
 *
 * Copyright (C) 2001
 * Brad Boyer ([email protected])
 * (C) 2003 Ardis Technologies <[email protected]>
 *
 * Handling of HFS wrappers around HFS+ volumes
 */

#include <linux/fs.h>
#include <linux/blkdev.h>
#include <linux/cdrom.h>
#include <linux/genhd.h>
#include <asm/unaligned.h>

#include "hfsplus_fs.h"
#include "hfsplus_raw.h"

struct hfsplus_wd {
    u32 ablk_size;
    u16 ablk_start;
    u16 embed_start;
    u16 embed_count;
};

static void hfsplus_end_io_sync(struct bio *bio, int err)
{
    if (err)
        clear_bit(BIO_UPTODATE, &bio->bi_flags);
    complete(bio->bi_private);
}

/*
 * hfsplus_submit_bio - Perfrom block I/O
 * @sb: super block of volume for I/O
 * @sector: block to read or write, for blocks of HFSPLUS_SECTOR_SIZE bytes
 * @buf: buffer for I/O
 * @data: output pointer for location of requested data
 * @rw: direction of I/O
 *
 * The unit of I/O is hfsplus_min_io_size(sb), which may be bigger than
 * HFSPLUS_SECTOR_SIZE, and @buf must be sized accordingly. On reads
 * @data will return a pointer to the start of the requested sector,
 * which may not be the same location as @buf.
 *
 * If @sector is not aligned to the bdev logical block size it will
 * be rounded down. For writes this means that @buf should contain data
 * that starts at the rounded-down address. As long as the data was
 * read using hfsplus_submit_bio() and the same buffer is used things
 * will work correctly.
 */
int hfsplus_submit_bio(struct super_block *sb, sector_t sector,
        void *buf, void **data, int rw)
{
    DECLARE_COMPLETION_ONSTACK(wait);
    struct bio *bio;
    int ret = 0;
    u64 io_size;
    loff_t start;
    int offset;

    /*
     * Align sector to hardware sector size and find offset. We
     * assume that io_size is a power of two, which _should_
     * be true.
     */
    io_size = hfsplus_min_io_size(sb);
    start = (loff_t)sector << HFSPLUS_SECTOR_SHIFT;
    offset = start & (io_size - 1);
    sector &= ~((io_size >> HFSPLUS_SECTOR_SHIFT) - 1);

    bio = bio_alloc(GFP_NOIO, 1);
    bio->bi_sector = sector;
    bio->bi_bdev = sb->s_bdev;
    bio->bi_end_io = hfsplus_end_io_sync;
    bio->bi_private = &wait;

    if (!(rw & WRITE) && data)
        *data = (u8 *)buf + offset;

    while (io_size > 0) {
        unsigned int page_offset = offset_in_page(buf);
        unsigned int len = min_t(unsigned int, PAGE_SIZE - page_offset,
                     io_size);

        ret = bio_add_page(bio, virt_to_page(buf), len, page_offset);
        if (ret != len) {
            ret = -EIO;
            goto out;
        }
        io_size -= len;
        buf = (u8 *)buf + len;
    }

    submit_bio(rw, bio);
    wait_for_completion(&wait);

    if (!bio_flagged(bio, BIO_UPTODATE))
        ret = -EIO;

out:
    bio_put(bio);
    return ret < 0 ? ret : 0;
}

static int hfsplus_read_mdb(void *bufptr, struct hfsplus_wd *wd)
{
    u32 extent;
    u16 attrib;
    __be16 sig;

    sig = *(__be16 *)(bufptr + HFSP_WRAPOFF_EMBEDSIG);
    if (sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIG) &&
        sig != cpu_to_be16(HFSPLUS_VOLHEAD_SIGX))
        return 0;

    attrib = be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ATTRIB));
    if (!(attrib & HFSP_WRAP_ATTRIB_SLOCK) ||
       !(attrib & HFSP_WRAP_ATTRIB_SPARED))
        return 0;

    wd->ablk_size =
        be32_to_cpu(*(__be32 *)(bufptr + HFSP_WRAPOFF_ABLKSIZE));
    if (wd->ablk_size < HFSPLUS_SECTOR_SIZE)
        return 0;
    if (wd->ablk_size % HFSPLUS_SECTOR_SIZE)
        return 0;
    wd->ablk_start =
        be16_to_cpu(*(__be16 *)(bufptr + HFSP_WRAPOFF_ABLKSTART));

    extent = get_unaligned_be32(bufptr + HFSP_WRAPOFF_EMBEDEXT);
    wd->embed_start = (extent >> 16) & 0xFFFF;
    wd->embed_count = extent & 0xFFFF;

    return 1;
}

static int hfsplus_get_last_session(struct super_block *sb,
                    sector_t *start, sector_t *size)
{
    struct cdrom_multisession ms_info;
    struct cdrom_tocentry te;
    int res;

    /* default values */
    *start = 0;
    *size = sb->s_bdev->bd_inode->i_size >> 9;

    if (HFSPLUS_SB(sb)->session >= 0) {
        te.cdte_track = HFSPLUS_SB(sb)->session;
        te.cdte_format = CDROM_LBA;
        res = ioctl_by_bdev(sb->s_bdev,
            CDROMREADTOCENTRY, (unsigned long)&te);
        if (!res && (te.cdte_ctrl & CDROM_DATA_TRACK) == 4) {
            *start = (sector_t)te.cdte_addr.lba << 2;
            return 0;
        }
        printk(KERN_ERR "hfs: invalid session number or type of track\n");
        return -EINVAL;
    }
    ms_info.addr_format = CDROM_LBA;
    res = ioctl_by_bdev(sb->s_bdev, CDROMMULTISESSION,
        (unsigned long)&ms_info);
    if (!res && ms_info.xa_flag)
        *start = (sector_t)ms_info.addr.lba << 2;
    return 0;
}

/* Find the volume header and fill in some minimum bits in superblock */
/* Takes in super block, returns true if good data read */
int hfsplus_read_wrapper(struct super_block *sb)
{
    struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
    struct hfsplus_wd wd;
    sector_t part_start, part_size;
    u32 blocksize;
    int error = 0;

    error = -EINVAL;
    blocksize = sb_min_blocksize(sb, HFSPLUS_SECTOR_SIZE);
    if (!blocksize)
        goto out;

    if (hfsplus_get_last_session(sb, &part_start, &part_size))
        goto out;

    error = -ENOMEM;
    sbi->s_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
    if (!sbi->s_vhdr_buf)
        goto out;
    sbi->s_backup_vhdr_buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
    if (!sbi->s_backup_vhdr_buf)
        goto out_free_vhdr;

reread:
    error = hfsplus_submit_bio(sb, part_start + HFSPLUS_VOLHEAD_SECTOR,
                   sbi->s_vhdr_buf, (void **)&sbi->s_vhdr,
                   READ);
    if (error)
        goto out_free_backup_vhdr;

    error = -EINVAL;
    switch (sbi->s_vhdr->signature) {
    case cpu_to_be16(HFSPLUS_VOLHEAD_SIGX):
        set_bit(HFSPLUS_SB_HFSX, &sbi->flags);
        /*FALLTHRU*/
    case cpu_to_be16(HFSPLUS_VOLHEAD_SIG):
        break;
    case cpu_to_be16(HFSP_WRAP_MAGIC):
        if (!hfsplus_read_mdb(sbi->s_vhdr, &wd))
            goto out_free_backup_vhdr;
        wd.ablk_size >>= HFSPLUS_SECTOR_SHIFT;
        part_start += (sector_t)wd.ablk_start +
                   (sector_t)wd.embed_start * wd.ablk_size;
        part_size = (sector_t)wd.embed_count * wd.ablk_size;
        goto reread;
    default:
        /*
         * Check for a partition block.
         *
         * (should do this only for cdrom/loop though)
         */
        if (hfs_part_find(sb, &part_start, &part_size))
            goto out_free_backup_vhdr;
        goto reread;
    }

    error = hfsplus_submit_bio(sb, part_start + part_size - 2,
                   sbi->s_backup_vhdr_buf,
                   (void **)&sbi->s_backup_vhdr, READ);
    if (error)
        goto out_free_backup_vhdr;

    error = -EINVAL;
    if (sbi->s_backup_vhdr->signature != sbi->s_vhdr->signature) {
        printk(KERN_WARNING
            "hfs: invalid secondary volume header\n");
        goto out_free_backup_vhdr;
    }

    blocksize = be32_to_cpu(sbi->s_vhdr->blocksize);

    /*
     * Block size must be at least as large as a sector and a multiple of 2.
     */
    if (blocksize < HFSPLUS_SECTOR_SIZE || ((blocksize - 1) & blocksize))
        goto out_free_backup_vhdr;
    sbi->alloc_blksz = blocksize;
    sbi->alloc_blksz_shift = 0;
    while ((blocksize >>= 1) != 0)
        sbi->alloc_blksz_shift++;
    blocksize = min(sbi->alloc_blksz, (u32)PAGE_SIZE);

    /*
     * Align block size to block offset.
     */
    while (part_start & ((blocksize >> HFSPLUS_SECTOR_SHIFT) - 1))
        blocksize >>= 1;

    if (sb_set_blocksize(sb, blocksize) != blocksize) {
        printk(KERN_ERR "hfs: unable to set blocksize to %u!\n",
            blocksize);
        goto out_free_backup_vhdr;
    }

    sbi->blockoffset =
        part_start >> (sb->s_blocksize_bits - HFSPLUS_SECTOR_SHIFT);
    sbi->part_start = part_start;
    sbi->sect_count = part_size;
    sbi->fs_shift = sbi->alloc_blksz_shift - sb->s_blocksize_bits;
    return 0;

out_free_backup_vhdr:
    kfree(sbi->s_backup_vhdr_buf);
out_free_vhdr:
    kfree(sbi->s_vhdr_buf);
out:
    return error;
}