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 
qnx6_mmi_copy_sb(struct qnx6_super_block * qsb,struct qnx6_mmi_super_block * sb)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 
qnx6_mmi_fill_super(struct super_block * s,int silent)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 }
150