GNU Linux-libre 4.9.308-gnu1
[releases.git] / 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 }