fs/qnx6/super_mmi.c

Source file repositories/reference/linux-study-clean/fs/qnx6/super_mmi.c

File Facts

System
Linux kernel
Corpus path
fs/qnx6/super_mmi.c
Extension
.c
Size
3871 bytes
Lines
150
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

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:

Annotation

Implementation Notes