// SPDX-License-Identifier: GPL-2.0
/*
 * QNX6 file system, Linux implementation.
 *
 * Version : 1.0.0
 *
 * History :
 *
 * 01-02-2012 by Kai Bankett (chaosman@ontika.net) : first release.
 *
 */

#include <linux/buffer_head.h>
#include <linux/slab.h>
#include <linux/crc32.h>
#include "qnx6.h"

static void qnx6_mmi_copy_sb(struct qnx6_super_block *qsb,
                struct qnx6_mmi_super_block *sb)
{
        qsb->sb_magic = sb->sb_magic;
        qsb->sb_checksum = sb->sb_checksum;
        qsb->sb_serial = sb->sb_serial;
        qsb->sb_blocksize = sb->sb_blocksize;
        qsb->sb_num_inodes = sb->sb_num_inodes;
        qsb->sb_free_inodes = sb->sb_free_inodes;
        qsb->sb_num_blocks = sb->sb_num_blocks;
        qsb->sb_free_blocks = sb->sb_free_blocks;

        /* the rest of the superblock is the same */
        memcpy(&qsb->Inode, &sb->Inode, sizeof(sb->Inode));
        memcpy(&qsb->Bitmap, &sb->Bitmap, sizeof(sb->Bitmap));
        memcpy(&qsb->Longfile, &sb->Longfile, sizeof(sb->Longfile));
}

struct qnx6_super_block *qnx6_mmi_fill_super(struct super_block *s, int silent)
{
        struct buffer_head *bh1, *bh2 = NULL;
        struct qnx6_mmi_super_block *sb1, *sb2;
        struct qnx6_super_block *qsb = NULL;
        struct qnx6_sb_info *sbi;
        __u64 offset;

        /* Check the superblock signatures
           start with the first superblock */
        bh1 = sb_bread(s, 0);
        if (!bh1) {
                pr_err("Unable to read first mmi superblock\n");
                return NULL;
        }
        sb1 = (struct qnx6_mmi_super_block *)bh1->b_data;
        sbi = QNX6_SB(s);
        if (fs32_to_cpu(sbi, sb1->sb_magic) != QNX6_SUPER_MAGIC) {
                if (!silent) {
                        pr_err("wrong signature (magic) in superblock #1.\n");
                        goto out;
                }
        }

        /* checksum check - start at byte 8 and end at byte 512 */
        if (fs32_to_cpu(sbi, sb1->sb_checksum) !=
                                crc32_be(0, (char *)(bh1->b_data + 8), 504)) {
                pr_err("superblock #1 checksum error\n");
                goto out;
        }

        /* calculate second superblock blocknumber */
        offset = fs32_to_cpu(sbi, sb1->sb_num_blocks) + QNX6_SUPERBLOCK_AREA /
                                        fs32_to_cpu(sbi, sb1->sb_blocksize);

        /* set new blocksize */
        if (!sb_set_blocksize(s, fs32_to_cpu(sbi, sb1->sb_blocksize))) {
                pr_err("unable to set blocksize\n");
                goto out;
        }
        /* blocksize invalidates bh - pull it back in */
        brelse(bh1);
        bh1 = sb_bread(s, 0);
        if (!bh1)
                goto out;
        sb1 = (struct qnx6_mmi_super_block *)bh1->b_data;

        /* read second superblock */
        bh2 = sb_bread(s, offset);
        if (!bh2) {
                pr_err("unable to read the second superblock\n");
                goto out;
        }
        sb2 = (struct qnx6_mmi_super_block *)bh2->b_data;
        if (fs32_to_cpu(sbi, sb2->sb_magic) != QNX6_SUPER_MAGIC) {
                if (!silent)
                        pr_err("wrong signature (magic) in superblock #2.\n");
                goto out;
        }

        /* checksum check - start at byte 8 and end at byte 512 */
        if (fs32_to_cpu(sbi, sb2->sb_checksum)
                        != crc32_be(0, (char *)(bh2->b_data + 8), 504)) {
                pr_err("superblock #1 checksum error\n");
                goto out;
        }

        qsb = kmalloc_obj(*qsb);
        if (!qsb) {
                pr_err("unable to allocate memory.\n");
                goto out;
        }

        if (fs64_to_cpu(sbi, sb1->sb_serial) >
                                        fs64_to_cpu(sbi, sb2->sb_serial)) {
                /* superblock #1 active */
                qnx6_mmi_copy_sb(qsb, sb1);
#ifdef CONFIG_QNX6FS_DEBUG
                qnx6_superblock_debug(qsb, s);
#endif
                memcpy(bh1->b_data, qsb, sizeof(struct qnx6_super_block));

                sbi->sb_buf = bh1;
                sbi->sb = (struct qnx6_super_block *)bh1->b_data;
                brelse(bh2);
                pr_info("superblock #1 active\n");
        } else {
                /* superblock #2 active */
                qnx6_mmi_copy_sb(qsb, sb2);
#ifdef CONFIG_QNX6FS_DEBUG
                qnx6_superblock_debug(qsb, s);
#endif
                memcpy(bh2->b_data, qsb, sizeof(struct qnx6_super_block));

                sbi->sb_buf = bh2;
                sbi->sb = (struct qnx6_super_block *)bh2->b_data;
                brelse(bh1);
                pr_info("superblock #2 active\n");
        }
        kfree(qsb);

        /* offset for mmi_fs is just SUPERBLOCK_AREA bytes */
        sbi->s_blks_off = QNX6_SUPERBLOCK_AREA / s->s_blocksize;

        /* success */
        return sbi->sb;

out:
        if (bh1 != NULL)
                brelse(bh1);
        if (bh2 != NULL)
                brelse(bh2);
        return NULL;
}