linux/block/early-lookup.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Code for looking up block devices in the early boot code before mounting the
 * root file system.
 */
#include <linux/blkdev.h>
#include <linux/ctype.h>

struct uuidcmp { … };

/**
 * match_dev_by_uuid - callback for finding a partition using its uuid
 * @dev:	device passed in by the caller
 * @data:	opaque pointer to the desired struct uuidcmp to match
 *
 * Returns 1 if the device matches, and 0 otherwise.
 */
static int __init match_dev_by_uuid(struct device *dev, const void *data)
{ … }

/**
 * devt_from_partuuid - looks up the dev_t of a partition by its UUID
 * @uuid_str:	char array containing ascii UUID
 * @devt:	dev_t result
 *
 * The function will return the first partition which contains a matching
 * UUID value in its partition_meta_info struct.  This does not search
 * by filesystem UUIDs.
 *
 * If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be
 * extracted and used as an offset from the partition identified by the UUID.
 *
 * Returns 0 on success or a negative error code on failure.
 */
static int __init devt_from_partuuid(const char *uuid_str, dev_t *devt)
{ … }

/**
 * match_dev_by_label - callback for finding a partition using its label
 * @dev:	device passed in by the caller
 * @data:	opaque pointer to the label to match
 *
 * Returns 1 if the device matches, and 0 otherwise.
 */
static int __init match_dev_by_label(struct device *dev, const void *data)
{ … }

static int __init devt_from_partlabel(const char *label, dev_t *devt)
{ … }

static dev_t __init blk_lookup_devt(const char *name, int partno)
{ … }

static int __init devt_from_devname(const char *name, dev_t *devt)
{ … }

static int __init devt_from_devnum(const char *name, dev_t *devt)
{ … }

/*
 *	Convert a name into device number.  We accept the following variants:
 *
 *	1) <hex_major><hex_minor> device number in hexadecimal represents itself
 *         no leading 0x, for example b302.
 *	3) /dev/<disk_name> represents the device number of disk
 *	4) /dev/<disk_name><decimal> represents the device number
 *         of partition - device number of disk plus the partition number
 *	5) /dev/<disk_name>p<decimal> - same as the above, that form is
 *	   used when disk name of partitioned disk ends on a digit.
 *	6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
 *	   unique id of a partition if the partition table provides it.
 *	   The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
 *	   partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
 *	   filled hex representation of the 32-bit "NT disk signature", and PP
 *	   is a zero-filled hex representation of the 1-based partition number.
 *	7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
 *	   a partition with a known unique id.
 *	8) <major>:<minor> major and minor number of the device separated by
 *	   a colon.
 *	9) PARTLABEL=<name> with name being the GPT partition label.
 *	   MSDOS partitions do not support labels!
 *
 *	If name doesn't have fall into the categories above, we return (0,0).
 *	block_class is used to check if something is a disk name. If the disk
 *	name contains slashes, the device name has them replaced with
 *	bangs.
 */
int __init early_lookup_bdev(const char *name, dev_t *devt)
{ … }

static char __init *bdevt_str(dev_t devt, char *buf)
{ … }

/*
 * print a full list of all partitions - intended for places where the root
 * filesystem can't be mounted and thus to give the victim some idea of what
 * went wrong
 */
void __init printk_all_partitions(void)
{ … }