fs/qnx6/super_mmi.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * QNX6 file system, Linux implementation.
   4  *
   5  * Version : 1.0.0
   6  *
   7  * History :
   8  *
   9  * 01-02-2012 by Kai Bankett (chaosman@ontika.net) : first release.
  10  *
  11  */
  12
  13 #include <linux/buffer_head.h>
  14 #include <linux/slab.h>
  15 #include <linux/crc32.h>
  16 #include "qnx6.h"
  17
  18 static void qnx6_mmi_copy_sb(struct qnx6_super_block *qsb,
  19                 struct qnx6_mmi_super_block *sb)
  20 {
  21         qsb->sb_magic = sb->sb_magic;
  22         qsb->sb_checksum = sb->sb_checksum;
  23         qsb->sb_serial = sb->sb_serial;
  24         qsb->sb_blocksize = sb->sb_blocksize;
  25         qsb->sb_num_inodes = sb->sb_num_inodes;
  26         qsb->sb_free_inodes = sb->sb_free_inodes;
  27         qsb->sb_num_blocks = sb->sb_num_blocks;
  28         qsb->sb_free_blocks = sb->sb_free_blocks;
  29
  30         /* the rest of the superblock is the same */
  31         memcpy(&qsb->Inode, &sb->Inode, sizeof(sb->Inode));
  32         memcpy(&qsb->Bitmap, &sb->Bitmap, sizeof(sb->Bitmap));
  33         memcpy(&qsb->Longfile, &sb->Longfile, sizeof(sb->Longfile));
  34 }
  35
  36 struct qnx6_super_block *qnx6_mmi_fill_super(struct super_block *s, int silent)
  37 {
  38         struct buffer_head *bh1, *bh2 = NULL;
  39         struct qnx6_mmi_super_block *sb1, *sb2;
  40         struct qnx6_super_block *qsb = NULL;
  41         struct qnx6_sb_info *sbi;
  42         __u64 offset;
  43
  44         /* Check the superblock signatures
  45            start with the first superblock */
  46         bh1 = sb_bread(s, 0);
  47         if (!bh1) {
  48                 pr_err("Unable to read first mmi superblock\n");
  49                 return NULL;
  50         }
  51         sb1 = (struct qnx6_mmi_super_block *)bh1->b_data;
  52         sbi = QNX6_SB(s);
  53         if (fs32_to_cpu(sbi, sb1->sb_magic) != QNX6_SUPER_MAGIC) {
  54                 if (!silent) {
  55                         pr_err("wrong signature (magic) in 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                 pr_err("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                 pr_err("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                 pr_err("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                         pr_err("wrong signature (magic) in superblock #2.\n");
  93                 goto out;
  94         }
  95
  96         /* checksum check - start at byte 8 and end at byte 512 */
  97         if (fs32_to_cpu(sbi, sb2->sb_checksum)
  98                         != crc32_be(0, (char *)(bh2->b_data + 8), 504)) {
  99                 pr_err("superblock #1 checksum error\n");
 100                 goto out;
 101         }
 102
 103         qsb = kmalloc(sizeof(*qsb), GFP_KERNEL);
 104         if (!qsb) {
 105                 pr_err("unable to allocate memory.\n");
 106                 goto out;
 107         }
 108
 109         if (fs64_to_cpu(sbi, sb1->sb_serial) >
 110                                         fs64_to_cpu(sbi, sb2->sb_serial)) {
 111                 /* superblock #1 active */
 112                 qnx6_mmi_copy_sb(qsb, sb1);
 113 #ifdef CONFIG_QNX6FS_DEBUG
 114                 qnx6_superblock_debug(qsb, s);
 115 #endif
 116                 memcpy(bh1->b_data, qsb, sizeof(struct qnx6_super_block));
 117
 118                 sbi->sb_buf = bh1;
 119                 sbi->sb = (struct qnx6_super_block *)bh1->b_data;
 120                 brelse(bh2);
 121                 pr_info("superblock #1 active\n");
 122         } else {
 123                 /* superblock #2 active */
 124                 qnx6_mmi_copy_sb(qsb, sb2);
 125 #ifdef CONFIG_QNX6FS_DEBUG
 126                 qnx6_superblock_debug(qsb, s);
 127 #endif
 128                 memcpy(bh2->b_data, qsb, sizeof(struct qnx6_super_block));
 129
 130                 sbi->sb_buf = bh2;
 131                 sbi->sb = (struct qnx6_super_block *)bh2->b_data;
 132                 brelse(bh1);
 133                 pr_info("superblock #2 active\n");
 134         }
 135         kfree(qsb);
 136
 137         /* offset for mmi_fs is just SUPERBLOCK_AREA bytes */
 138         sbi->s_blks_off = QNX6_SUPERBLOCK_AREA / s->s_blocksize;
 139
 140         /* success */
 141         return sbi->sb;
 142
 143 out:
 144         if (bh1 != NULL)
 145                 brelse(bh1);
 146         if (bh2 != NULL)
 147                 brelse(bh2);
 148         return NULL;
 149 }