fs/efs/super.c

Source file repositories/reference/linux-study-clean/fs/efs/super.c

File Facts

System
Linux kernel
Corpus path
fs/efs/super.c
Extension
.c
Size
8619 bytes
Lines
369
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: exported/initcall integration point
Status
integration 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

module_init(init_efs_fs)
module_exit(exit_efs_fs)

static efs_block_t efs_validate_vh(struct volume_header *vh) {
	int		i;
	__be32		cs, *ui;
	int		csum;
	efs_block_t	sblock = 0; /* shuts up gcc */
	struct pt_types	*pt_entry;
	int		pt_type, slice = -1;

	if (be32_to_cpu(vh->vh_magic) != VHMAGIC) {
		/*
		 * assume that we're dealing with a partition and allow
		 * read_super() to try and detect a valid superblock
		 * on the next block.
		 */
		return 0;
	}

	ui = ((__be32 *) (vh + 1)) - 1;
	for(csum = 0; ui >= ((__be32 *) vh);) {
		cs = *ui--;
		csum += be32_to_cpu(cs);
	}
	if (csum) {
		pr_warn("SGI disklabel: checksum bad, label corrupted\n");
		return 0;
	}

#ifdef DEBUG
	pr_debug("bf: \"%16s\"\n", vh->vh_bootfile);

	for(i = 0; i < NVDIR; i++) {
		int	j;
		char	name[VDNAMESIZE+1];

		for(j = 0; j < VDNAMESIZE; j++) {
			name[j] = vh->vh_vd[i].vd_name[j];
		}
		name[j] = (char) 0;

		if (name[0]) {
			pr_debug("vh: %8s block: 0x%08x size: 0x%08x\n",
				name, (int) be32_to_cpu(vh->vh_vd[i].vd_lbn),
				(int) be32_to_cpu(vh->vh_vd[i].vd_nbytes));
		}
	}
#endif

	for(i = 0; i < NPARTAB; i++) {
		pt_type = (int) be32_to_cpu(vh->vh_pt[i].pt_type);
		for(pt_entry = sgi_pt_types; pt_entry->pt_name; pt_entry++) {
			if (pt_type == pt_entry->pt_type) break;
		}
#ifdef DEBUG
		if (be32_to_cpu(vh->vh_pt[i].pt_nblks)) {
			pr_debug("pt %2d: start: %08d size: %08d type: 0x%02x (%s)\n",
				 i, (int)be32_to_cpu(vh->vh_pt[i].pt_firstlbn),
				 (int)be32_to_cpu(vh->vh_pt[i].pt_nblks),
				 pt_type, (pt_entry->pt_name) ?
				 pt_entry->pt_name : "unknown");
		}
#endif
		if (IS_EFS(pt_type)) {
			sblock = be32_to_cpu(vh->vh_pt[i].pt_firstlbn);
			slice = i;
		}
	}

	if (slice == -1) {
		pr_notice("partition table contained no EFS partitions\n");
#ifdef DEBUG
	} else {
		pr_info("using slice %d (type %s, offset 0x%x)\n", slice,
			(pt_entry->pt_name) ? pt_entry->pt_name : "unknown",
			sblock);
#endif
	}
	return sblock;
}

static int efs_validate_super(struct efs_sb_info *sb, struct efs_super *super) {

	if (!IS_EFS_MAGIC(be32_to_cpu(super->fs_magic)))
		return -1;

	sb->fs_magic     = be32_to_cpu(super->fs_magic);
	sb->total_blocks = be32_to_cpu(super->fs_size);
	sb->first_block  = be32_to_cpu(super->fs_firstcg);

Annotation

Implementation Notes