super_mmi.c

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/*
 * QNX6 file system, Linux implementation.
 *
 * Version : 1.0.0
 *
 * History :
 *
 * 01-02-2012 by Kai Bankett ([email protected]) : first release.
 *
 */

#include <linux/buffer_head.h>
#include <linux/slab.h>
#include <linux/crc32.h>
#include "qnx6.h"

static void qnx6_mmi_copy_sb(struct qnx6_super_block *qsb,
        struct qnx6_mmi_super_block *sb)
{
    qsb->sb_magic = sb->sb_magic;
    qsb->sb_checksum = sb->sb_checksum;
    qsb->sb_serial = sb->sb_serial;
    qsb->sb_blocksize = sb->sb_blocksize;
    qsb->sb_num_inodes = sb->sb_num_inodes;
    qsb->sb_free_inodes = sb->sb_free_inodes;
    qsb->sb_num_blocks = sb->sb_num_blocks;
    qsb->sb_free_blocks = sb->sb_free_blocks;

    /* the rest of the superblock is the same */
    memcpy(&qsb->Inode, &sb->Inode, sizeof(sb->Inode));
    memcpy(&qsb->Bitmap, &sb->Bitmap, sizeof(sb->Bitmap));
    memcpy(&qsb->Longfile, &sb->Longfile, sizeof(sb->Longfile));
}

struct qnx6_super_block *qnx6_mmi_fill_super(struct super_block *s, int silent)
{
    struct buffer_head *bh1, *bh2 = NULL;
    struct qnx6_mmi_super_block *sb1, *sb2;
    struct qnx6_super_block *qsb = NULL;
    struct qnx6_sb_info *sbi;
    __u64 offset;

    /* Check the superblock signatures
       start with the first superblock */
    bh1 = sb_bread(s, 0);
    if (!bh1) {
        printk(KERN_ERR "qnx6: Unable to read first mmi superblock\n");
        return NULL;
    }
    sb1 = (struct qnx6_mmi_super_block *)bh1->b_data;
    sbi = QNX6_SB(s);
    if (fs32_to_cpu(sbi, sb1->sb_magic) != QNX6_SUPER_MAGIC) {
        if (!silent) {
            printk(KERN_ERR "qnx6: wrong signature (magic) in"
                    " superblock #1.\n");
            goto out;
        }
    }

    /* checksum check - start at byte 8 and end at byte 512 */
    if (fs32_to_cpu(sbi, sb1->sb_checksum) !=
                crc32_be(0, (char *)(bh1->b_data + 8), 504)) {
        printk(KERN_ERR "qnx6: superblock #1 checksum error\n");
        goto out;
    }

    /* calculate second superblock blocknumber */
    offset = fs32_to_cpu(sbi, sb1->sb_num_blocks) + QNX6_SUPERBLOCK_AREA /
                    fs32_to_cpu(sbi, sb1->sb_blocksize);

    /* set new blocksize */
    if (!sb_set_blocksize(s, fs32_to_cpu(sbi, sb1->sb_blocksize))) {
        printk(KERN_ERR "qnx6: unable to set blocksize\n");
        goto out;
    }
    /* blocksize invalidates bh - pull it back in */
    brelse(bh1);
    bh1 = sb_bread(s, 0);
    if (!bh1)
        goto out;
    sb1 = (struct qnx6_mmi_super_block *)bh1->b_data;

    /* read second superblock */
    bh2 = sb_bread(s, offset);
    if (!bh2) {
        printk(KERN_ERR "qnx6: unable to read the second superblock\n");
        goto out;
    }
    sb2 = (struct qnx6_mmi_super_block *)bh2->b_data;
    if (fs32_to_cpu(sbi, sb2->sb_magic) != QNX6_SUPER_MAGIC) {
        if (!silent)
            printk(KERN_ERR "qnx6: wrong signature (magic) in"
                    " superblock #2.\n");
        goto out;
    }

    /* checksum check - start at byte 8 and end at byte 512 */
    if (fs32_to_cpu(sbi, sb2->sb_checksum)
            != crc32_be(0, (char *)(bh2->b_data + 8), 504)) {
        printk(KERN_ERR "qnx6: superblock #1 checksum error\n");
        goto out;
    }

    qsb = kmalloc(sizeof(*qsb), GFP_KERNEL);
    if (!qsb) {
        printk(KERN_ERR "qnx6: unable to allocate memory.\n");
        goto out;
    }

    if (fs64_to_cpu(sbi, sb1->sb_serial) >
                    fs64_to_cpu(sbi, sb2->sb_serial)) {
        /* superblock #1 active */
        qnx6_mmi_copy_sb(qsb, sb1);
#ifdef CONFIG_QNX6FS_DEBUG
        qnx6_superblock_debug(qsb, s);
#endif
        memcpy(bh1->b_data, qsb, sizeof(struct qnx6_super_block));

        sbi->sb_buf = bh1;
        sbi->sb = (struct qnx6_super_block *)bh1->b_data;
        brelse(bh2);
        printk(KERN_INFO "qnx6: superblock #1 active\n");
    } else {
        /* superblock #2 active */
        qnx6_mmi_copy_sb(qsb, sb2);
#ifdef CONFIG_QNX6FS_DEBUG
        qnx6_superblock_debug(qsb, s);
#endif
        memcpy(bh2->b_data, qsb, sizeof(struct qnx6_super_block));

        sbi->sb_buf = bh2;
        sbi->sb = (struct qnx6_super_block *)bh2->b_data;
        brelse(bh1);
        printk(KERN_INFO "qnx6: superblock #2 active\n");
    }
    kfree(qsb);

    /* offset for mmi_fs is just SUPERBLOCK_AREA bytes */
    sbi->s_blks_off = QNX6_SUPERBLOCK_AREA / s->s_blocksize;

    /* success */
    return sbi->sb;

out:
    if (bh1 != NULL)
        brelse(bh1);
    if (bh2 != NULL)
        brelse(bh2);
    return NULL;
}