kernel/fs/qnx6/super_mmi.c

   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
  17 static 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
  35 struct 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                 pr_err("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                         pr_err("wrong signature (magic) in superblock #1.\n");
  55                         goto out;
  56                 }
  57         }
  58
  59         /* checksum check - start at byte 8 and end at byte 512 */
  60         if (fs32_to_cpu(sbi, sb1->sb_checksum) !=
  61                                 crc32_be(0, (char *)(bh1->b_data + 8), 504)) {
  62                 pr_err("superblock #1 checksum error\n");
  63                 goto out;
  64         }
  65
  66         /* calculate second superblock blocknumber */
  67         offset = fs32_to_cpu(sbi, sb1->sb_num_blocks) + QNX6_SUPERBLOCK_AREA /
  68                                         fs32_to_cpu(sbi, sb1->sb_blocksize);
  69
  70         /* set new blocksize */
  71         if (!sb_set_blocksize(s, fs32_to_cpu(sbi, sb1->sb_blocksize))) {
  72                 pr_err("unable to set blocksize\n");
  73                 goto out;
  74         }
  75         /* blocksize invalidates bh - pull it back in */
  76         brelse(bh1);
  77         bh1 = sb_bread(s, 0);
  78         if (!bh1)
  79                 goto out;
  80         sb1 = (struct qnx6_mmi_super_block *)bh1->b_data;
  81
  82         /* read second superblock */
  83         bh2 = sb_bread(s, offset);
  84         if (!bh2) {
  85                 pr_err("unable to read the second superblock\n");
  86                 goto out;
  87         }
  88         sb2 = (struct qnx6_mmi_super_block *)bh2->b_data;
  89         if (fs32_to_cpu(sbi, sb2->sb_magic) != QNX6_SUPER_MAGIC) {
  90                 if (!silent)
  91                         pr_err("wrong signature (magic) in superblock #2.\n");
  92                 goto out;
  93         }
  94
  95         /* checksum check - start at byte 8 and end at byte 512 */
  96         if (fs32_to_cpu(sbi, sb2->sb_checksum)
  97                         != crc32_be(0, (char *)(bh2->b_data + 8), 504)) {
  98                 pr_err("superblock #1 checksum error\n");
  99                 goto out;
 100         }
 101
 102         qsb = kmalloc(sizeof(*qsb), GFP_KERNEL);
 103         if (!qsb) {
 104                 pr_err("unable to allocate memory.\n");
 105                 goto out;
 106         }
 107
 108         if (fs64_to_cpu(sbi, sb1->sb_serial) >
 109                                         fs64_to_cpu(sbi, sb2->sb_serial)) {
 110                 /* superblock #1 active */
 111                 qnx6_mmi_copy_sb(qsb, sb1);
 112 #ifdef CONFIG_QNX6FS_DEBUG
 113                 qnx6_superblock_debug(qsb, s);
 114 #endif
 115                 memcpy(bh1->b_data, qsb, sizeof(struct qnx6_super_block));
 116
 117                 sbi->sb_buf = bh1;
 118                 sbi->sb = (struct qnx6_super_block *)bh1->b_data;
 119                 brelse(bh2);
 120                 pr_info("superblock #1 active\n");
 121         } else {
 122                 /* superblock #2 active */
 123                 qnx6_mmi_copy_sb(qsb, sb2);
 124 #ifdef CONFIG_QNX6FS_DEBUG
 125                 qnx6_superblock_debug(qsb, s);
 126 #endif
 127                 memcpy(bh2->b_data, qsb, sizeof(struct qnx6_super_block));
 128
 129                 sbi->sb_buf = bh2;
 130                 sbi->sb = (struct qnx6_super_block *)bh2->b_data;
 131                 brelse(bh1);
 132                 pr_info("superblock #2 active\n");
 133         }
 134         kfree(qsb);
 135
 136         /* offset for mmi_fs is just SUPERBLOCK_AREA bytes */
 137         sbi->s_blks_off = QNX6_SUPERBLOCK_AREA / s->s_blocksize;
 138
 139         /* success */
 140         return sbi->sb;
 141
 142 out:
 143         if (bh1 != NULL)
 144                 brelse(bh1);
 145         if (bh2 != NULL)
 146                 brelse(bh2);
 147         return NULL;
 148 }