block/partitions/sgi.c

Source file repositories/reference/linux-study-clean/block/partitions/sgi.c

File Facts

System
Linux kernel
Corpus path
block/partitions/sgi.c
Extension
.c
Size
2267 bytes
Lines
86
Domain
Representative Device Path
Bucket
PCIe NVMe Storage Path
Inferred role
Representative Device Path: implementation source
Status
source implementation candidate

Why This File Exists

Part of the selected hardware vertical slice: PCI discovery, driver binding, NVMe queues, block requests, DMA, interrupts, and completion.

Dependency Surface

Detected Declarations

Annotated Snippet

struct sgi_disklabel {
	__be32 magic_mushroom;		/* Big fat spliff... */
	__be16 root_part_num;		/* Root partition number */
	__be16 swap_part_num;		/* Swap partition number */
	s8 boot_file[16];		/* Name of boot file for ARCS */
	u8 _unused0[48];		/* Device parameter useless crapola.. */
	struct sgi_volume {
		s8 name[8];		/* Name of volume */
		__be32 block_num;		/* Logical block number */
		__be32 num_bytes;		/* How big, in bytes */
	} volume[15];
	struct sgi_partition {
		__be32 num_blocks;		/* Size in logical blocks */
		__be32 first_block;	/* First logical block */
		__be32 type;		/* Type of this partition */
	} partitions[16];
	__be32 csum;			/* Disk label checksum */
	__be32 _unused1;			/* Padding */
};

int sgi_partition(struct parsed_partitions *state)
{
	int i, csum;
	__be32 magic;
	int slot = 1;
	unsigned int start, blocks;
	__be32 *ui, cs;
	Sector sect;
	struct sgi_disklabel *label;
	struct sgi_partition *p;

	label = read_part_sector(state, 0, &sect);
	if (!label)
		return -1;
	p = &label->partitions[0];
	magic = label->magic_mushroom;
	if(be32_to_cpu(magic) != SGI_LABEL_MAGIC) {
		put_dev_sector(sect);
		return 0;
	}
	ui = ((__be32 *) (label + 1)) - 1;
	for(csum = 0; ui >= ((__be32 *) label);) {
		cs = *ui--;
		csum += be32_to_cpu(cs);
	}
	if(csum) {
		printk(KERN_WARNING "Dev %s SGI disklabel: csum bad, label corrupted\n",
		       state->disk->disk_name);
		put_dev_sector(sect);
		return 0;
	}
	/* All SGI disk labels have 16 partitions, disks under Linux only
	 * have 15 minor's.  Luckily there are always a few zero length
	 * partitions which we don't care about so we never overflow the
	 * current_minor.
	 */
	for(i = 0; i < 16; i++, p++) {
		blocks = be32_to_cpu(p->num_blocks);
		start  = be32_to_cpu(p->first_block);
		if (blocks) {
			put_partition(state, slot, start, blocks);
			if (be32_to_cpu(p->type) == LINUX_RAID_PARTITION)
				state->parts[slot].flags = ADDPART_FLAG_RAID;
		}
		slot++;
	}
	seq_buf_puts(&state->pp_buf, "\n");
	put_dev_sector(sect);
	return 1;
}

Annotation

Implementation Notes