linux/fs/qnx6/super_mmi.c
<<
>>
Prefs
   1/*
   2 * QNX6 file system, Linux implementation.
   3 *
   4 * Version : 1.0.0
   5 *
   6 * History :
   7 *
   8 * 01-02-2012 by Kai Bankett (chaosman@ontika.net) : first release.
   9 *
  10 */
  11
  12#include <linux/buffer_head.h>
  13#include <linux/slab.h>
  14#include <linux/crc32.h>
  15#include "qnx6.h"
  16
  17static void qnx6_mmi_copy_sb(struct qnx6_super_block *qsb,
  18                struct qnx6_mmi_super_block *sb)
  19{
  20        qsb->sb_magic = sb->sb_magic;
  21        qsb->sb_checksum = sb->sb_checksum;
  22        qsb->sb_serial = sb->sb_serial;
  23        qsb->sb_blocksize = sb->sb_blocksize;
  24        qsb->sb_num_inodes = sb->sb_num_inodes;
  25        qsb->sb_free_inodes = sb->sb_free_inodes;
  26        qsb->sb_num_blocks = sb->sb_num_blocks;
  27        qsb->sb_free_blocks = sb->sb_free_blocks;
  28
  29        /* the rest of the superblock is the same */
  30        memcpy(&qsb->Inode, &sb->Inode, sizeof(sb->Inode));
  31        memcpy(&qsb->Bitmap, &sb->Bitmap, sizeof(sb->Bitmap));
  32        memcpy(&qsb->Longfile, &sb->Longfile, sizeof(sb->Longfile));
  33}
  34
  35struct qnx6_super_block *qnx6_mmi_fill_super(struct super_block *s, int silent)
  36{
  37        struct buffer_head *bh1, *bh2 = NULL;
  38        struct qnx6_mmi_super_block *sb1, *sb2;
  39        struct qnx6_super_block *qsb = NULL;
  40        struct qnx6_sb_info *sbi;
  41        __u64 offset;
  42
  43        /* Check the superblock signatures
  44           start with the first superblock */
  45        bh1 = sb_bread(s, 0);
  46        if (!bh1) {
  47                printk(KERN_ERR "qnx6: Unable to read first mmi superblock\n");
  48                return NULL;
  49        }
  50        sb1 = (struct qnx6_mmi_super_block *)bh1->b_data;
  51        sbi = QNX6_SB(s);
  52        if (fs32_to_cpu(sbi, sb1->sb_magic) != QNX6_SUPER_MAGIC) {
  53                if (!silent) {
  54                        printk(KERN_ERR "qnx6: wrong signature (magic) in"
  55                                        " superblock #1.\n");
  56                        goto out;
  57                }
  58        }
  59
  60        /* checksum check - start at byte 8 and end at byte 512 */
  61        if (fs32_to_cpu(sbi, sb1->sb_checksum) !=
  62                                crc32_be(0, (char *)(bh1->b_data + 8), 504)) {
  63                printk(KERN_ERR "qnx6: superblock #1 checksum error\n");
  64                goto out;
  65        }
  66
  67        /* calculate second superblock blocknumber */
  68        offset = fs32_to_cpu(sbi, sb1->sb_num_blocks) + QNX6_SUPERBLOCK_AREA /
  69                                        fs32_to_cpu(sbi, sb1->sb_blocksize);
  70
  71        /* set new blocksize */
  72        if (!sb_set_blocksize(s, fs32_to_cpu(sbi, sb1->sb_blocksize))) {
  73                printk(KERN_ERR "qnx6: unable to set blocksize\n");
  74                goto out;
  75        }
  76        /* blocksize invalidates bh - pull it back in */
  77        brelse(bh1);
  78        bh1 = sb_bread(s, 0);
  79        if (!bh1)
  80                goto out;
  81        sb1 = (struct qnx6_mmi_super_block *)bh1->b_data;
  82
  83        /* read second superblock */
  84        bh2 = sb_bread(s, offset);
  85        if (!bh2) {
  86                printk(KERN_ERR "qnx6: unable to read the second superblock\n");
  87                goto out;
  88        }
  89        sb2 = (struct qnx6_mmi_super_block *)bh2->b_data;
  90        if (fs32_to_cpu(sbi, sb2->sb_magic) != QNX6_SUPER_MAGIC) {
  91                if (!silent)
  92                        printk(KERN_ERR "qnx6: wrong signature (magic) in"
  93                                        " superblock #2.\n");
  94                goto out;
  95        }
  96
  97        /* checksum check - start at byte 8 and end at byte 512 */
  98        if (fs32_to_cpu(sbi, sb2->sb_checksum)
  99                        != crc32_be(0, (char *)(bh2->b_data + 8), 504)) {
 100                printk(KERN_ERR "qnx6: superblock #1 checksum error\n");
 101                goto out;
 102        }
 103
 104        qsb = kmalloc(sizeof(*qsb), GFP_KERNEL);
 105        if (!qsb) {
 106                printk(KERN_ERR "qnx6: unable to allocate memory.\n");
 107                goto out;
 108        }
 109
 110        if (fs64_to_cpu(sbi, sb1->sb_serial) >
 111                                        fs64_to_cpu(sbi, sb2->sb_serial)) {
 112                /* superblock #1 active */
 113                qnx6_mmi_copy_sb(qsb, sb1);
 114#ifdef CONFIG_QNX6FS_DEBUG
 115                qnx6_superblock_debug(qsb, s);
 116#endif
 117                memcpy(bh1->b_data, qsb, sizeof(struct qnx6_super_block));
 118
 119                sbi->sb_buf = bh1;
 120                sbi->sb = (struct qnx6_super_block *)bh1->b_data;
 121                brelse(bh2);
 122                printk(KERN_INFO "qnx6: superblock #1 active\n");
 123        } else {
 124                /* superblock #2 active */
 125                qnx6_mmi_copy_sb(qsb, sb2);
 126#ifdef CONFIG_QNX6FS_DEBUG
 127                qnx6_superblock_debug(qsb, s);
 128#endif
 129                memcpy(bh2->b_data, qsb, sizeof(struct qnx6_super_block));
 130
 131                sbi->sb_buf = bh2;
 132                sbi->sb = (struct qnx6_super_block *)bh2->b_data;
 133                brelse(bh1);
 134                printk(KERN_INFO "qnx6: superblock #2 active\n");
 135        }
 136        kfree(qsb);
 137
 138        /* offset for mmi_fs is just SUPERBLOCK_AREA bytes */
 139        sbi->s_blks_off = QNX6_SUPERBLOCK_AREA / s->s_blocksize;
 140
 141        /* success */
 142        return sbi->sb;
 143
 144out:
 145        if (bh1 != NULL)
 146                brelse(bh1);
 147        if (bh2 != NULL)
 148                brelse(bh2);
 149        return NULL;
 150}
 151
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.