Commit 702f3189 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

block: move the code to do early boot lookup of block devices to block/ 



Create a new block/early-lookup.c to keep the early block device lookup
code instead of having this code sit with the early mount code.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230531125535.676098-16-hch@lst.de


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 079caa35

Documentation/admin-guide/kernel-parameters.txt

+2 −2
Original line number Diff line number Diff line
@@ -5453,8 +5453,8 @@ 


	root=		[KNL] Root filesystem

			Usually this a a block device specifier of some kind,

			see the early_lookup_bdev comment in init/do_mounts.c

			for details.

			see the early_lookup_bdev comment in

			block/early-lookup.c for details.

			Alternatively this can be "ram" for the legacy initial

			ramdisk, "nfs" and "cifs" for root on a network file

			system, or "mtd" and "ubi" for mounting from raw flash.

block/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -9,7 +9,7 @@ obj-y := bdev.o fops.o bio.o elevator.o blk-core.o blk-sysfs.o \ 
			blk-lib.o blk-mq.o blk-mq-tag.o blk-stat.o \

			blk-mq-sysfs.o blk-mq-cpumap.o blk-mq-sched.o ioctl.o \

			genhd.o ioprio.o badblocks.o partitions/ blk-rq-qos.o \

			disk-events.o blk-ia-ranges.o

			disk-events.o blk-ia-ranges.o early-lookup.o



obj-$(CONFIG_BOUNCE)		+= bounce.o

obj-$(CONFIG_BLK_DEV_BSG_COMMON) += bsg.o

block/early-lookup.c

0 → 100644
+224 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

/*

 * Code for looking up block devices in the early boot code before mounting the

 * root file system.  Unfortunately currently also abused in a few other places.

 */

#include <linux/blkdev.h>

#include <linux/ctype.h>



struct uuidcmp {

	const char *uuid;

	int len;

};



/**

 * 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 match_dev_by_uuid(struct device *dev, const void *data)

{

	struct block_device *bdev = dev_to_bdev(dev);

	const struct uuidcmp *cmp = data;



	if (!bdev->bd_meta_info ||

	    strncasecmp(cmp->uuid, bdev->bd_meta_info->uuid, cmp->len))

		return 0;

	return 1;

}



/**

 * devt_from_partuuid - looks up the dev_t of a partition by its UUID

 * @uuid_str:	char array containing ascii UUID

 *

 * 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 the matching dev_t on success or 0 on failure.

 */

static int devt_from_partuuid(const char *uuid_str, dev_t *devt)

{

	struct uuidcmp cmp;

	struct device *dev = NULL;

	int offset = 0;

	char *slash;



	cmp.uuid = uuid_str;



	slash = strchr(uuid_str, '/');

	/* Check for optional partition number offset attributes. */

	if (slash) {

		char c = 0;



		/* Explicitly fail on poor PARTUUID syntax. */

		if (sscanf(slash + 1, "PARTNROFF=%d%c", &offset, &c) != 1)

			goto out_invalid;

		cmp.len = slash - uuid_str;

	} else {

		cmp.len = strlen(uuid_str);

	}



	if (!cmp.len)

		goto out_invalid;



	dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid);

	if (!dev)

		return -ENODEV;



	if (offset) {

		/*

		 * Attempt to find the requested partition by adding an offset

		 * to the partition number found by UUID.

		 */

		*devt = part_devt(dev_to_disk(dev),

				  dev_to_bdev(dev)->bd_partno + offset);

	} else {

		*devt = dev->devt;

	}



	put_device(dev);

	return 0;



out_invalid:

	pr_err("VFS: PARTUUID= is invalid.\n"

	       "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");

	return -EINVAL;

}



/**

 * 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 match_dev_by_label(struct device *dev, const void *data)

{

	struct block_device *bdev = dev_to_bdev(dev);

	const char *label = data;



	if (!bdev->bd_meta_info || strcmp(label, bdev->bd_meta_info->volname))

		return 0;

	return 1;

}



static int devt_from_partlabel(const char *label, dev_t *devt)

{

	struct device *dev;



	dev = class_find_device(&block_class, NULL, label, &match_dev_by_label);

	if (!dev)

		return -ENODEV;

	*devt = dev->devt;

	put_device(dev);

	return 0;

}



static int devt_from_devname(const char *name, dev_t *devt)

{

	int part;

	char s[32];

	char *p;



	if (strlen(name) > 31)

		return -EINVAL;

	strcpy(s, name);

	for (p = s; *p; p++) {

		if (*p == '/')

			*p = '!';

	}



	*devt = blk_lookup_devt(s, 0);

	if (*devt)

		return 0;



	/*

	 * Try non-existent, but valid partition, which may only exist after

	 * opening the device, like partitioned md devices.

	 */

	while (p > s && isdigit(p[-1]))

		p--;

	if (p == s || !*p || *p == '0')

		return -EINVAL;



	/* try disk name without <part number> */

	part = simple_strtoul(p, NULL, 10);

	*p = '\0';

	*devt = blk_lookup_devt(s, part);

	if (*devt)

		return 0;



	/* try disk name without p<part number> */

	if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')

		return -EINVAL;

	p[-1] = '\0';

	*devt = blk_lookup_devt(s, part);

	if (*devt)

		return 0;

	return -EINVAL;

}



static int devt_from_devnum(const char *name, dev_t *devt)

{

	unsigned maj, min, offset;

	char *p, dummy;



	if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2 ||

	    sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3) {

		*devt = MKDEV(maj, min);

		if (maj != MAJOR(*devt) || min != MINOR(*devt))

			return -EINVAL;

	} else {

		*devt = new_decode_dev(simple_strtoul(name, &p, 16));

		if (*p)

			return -EINVAL;

	}



	return 0;

}



/*

 *	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 early_lookup_bdev(const char *name, dev_t *devt)

{

	if (strncmp(name, "PARTUUID=", 9) == 0)

		return devt_from_partuuid(name + 9, devt);

	if (strncmp(name, "PARTLABEL=", 10) == 0)

		return devt_from_partlabel(name + 10, devt);

	if (strncmp(name, "/dev/", 5) == 0)

		return devt_from_devname(name + 5, devt);

	return devt_from_devnum(name, devt);

}

EXPORT_SYMBOL_GPL(early_lookup_bdev);

init/do_mounts.c

+0 −219
Original line number Diff line number Diff line
@@ -59,225 +59,6 @@ static int __init readwrite(char *str) 
__setup("ro", readonly);

__setup("rw", readwrite);



#ifdef CONFIG_BLOCK

struct uuidcmp {

	const char *uuid;

	int len;

};



/**

 * 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 match_dev_by_uuid(struct device *dev, const void *data)

{

	struct block_device *bdev = dev_to_bdev(dev);

	const struct uuidcmp *cmp = data;



	if (!bdev->bd_meta_info ||

	    strncasecmp(cmp->uuid, bdev->bd_meta_info->uuid, cmp->len))

		return 0;

	return 1;

}



/**

 * devt_from_partuuid - looks up the dev_t of a partition by its UUID

 * @uuid_str:	char array containing ascii UUID

 *

 * 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 the matching dev_t on success or 0 on failure.

 */

static int devt_from_partuuid(const char *uuid_str, dev_t *devt)

{

	struct uuidcmp cmp;

	struct device *dev = NULL;

	int offset = 0;

	char *slash;



	cmp.uuid = uuid_str;



	slash = strchr(uuid_str, '/');

	/* Check for optional partition number offset attributes. */

	if (slash) {

		char c = 0;



		/* Explicitly fail on poor PARTUUID syntax. */

		if (sscanf(slash + 1, "PARTNROFF=%d%c", &offset, &c) != 1)

			goto out_invalid;

		cmp.len = slash - uuid_str;

	} else {

		cmp.len = strlen(uuid_str);

	}



	if (!cmp.len)

		goto out_invalid;



	dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid);

	if (!dev)

		return -ENODEV;



	if (offset) {

		/*

		 * Attempt to find the requested partition by adding an offset

		 * to the partition number found by UUID.

		 */

		*devt = part_devt(dev_to_disk(dev),

				  dev_to_bdev(dev)->bd_partno + offset);

	} else {

		*devt = dev->devt;

	}



	put_device(dev);

	return 0;



out_invalid:

	pr_err("VFS: PARTUUID= is invalid.\n"

	       "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");

	return -EINVAL;

}



/**

 * 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 match_dev_by_label(struct device *dev, const void *data)

{

	struct block_device *bdev = dev_to_bdev(dev);

	const char *label = data;



	if (!bdev->bd_meta_info || strcmp(label, bdev->bd_meta_info->volname))

		return 0;

	return 1;

}



static int devt_from_partlabel(const char *label, dev_t *devt)

{

	struct device *dev;



	dev = class_find_device(&block_class, NULL, label, &match_dev_by_label);

	if (!dev)

		return -ENODEV;

	*devt = dev->devt;

	put_device(dev);

	return 0;

}



static int devt_from_devname(const char *name, dev_t *devt)

{

	int part;

	char s[32];

	char *p;



	if (strlen(name) > 31)

		return -EINVAL;

	strcpy(s, name);

	for (p = s; *p; p++) {

		if (*p == '/')

			*p = '!';

	}



	*devt = blk_lookup_devt(s, 0);

	if (*devt)

		return 0;



	/*

	 * Try non-existent, but valid partition, which may only exist after

	 * opening the device, like partitioned md devices.

	 */

	while (p > s && isdigit(p[-1]))

		p--;

	if (p == s || !*p || *p == '0')

		return -EINVAL;



	/* try disk name without <part number> */

	part = simple_strtoul(p, NULL, 10);

	*p = '\0';

	*devt = blk_lookup_devt(s, part);

	if (*devt)

		return 0;



	/* try disk name without p<part number> */

	if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')

		return -EINVAL;

	p[-1] = '\0';

	*devt = blk_lookup_devt(s, part);

	if (*devt)

		return 0;

	return -EINVAL;

}



static int devt_from_devnum(const char *name, dev_t *devt)

{

	unsigned maj, min, offset;

	char *p, dummy;



	if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2 ||

	    sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3) {

		*devt = MKDEV(maj, min);

		if (maj != MAJOR(*devt) || min != MINOR(*devt))

			return -EINVAL;

	} else {

		*devt = new_decode_dev(simple_strtoul(name, &p, 16));

		if (*p)

			return -EINVAL;

	}



	return 0;

}



/*

 *	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 early_lookup_bdev(const char *name, dev_t *devt)

{

	if (strncmp(name, "PARTUUID=", 9) == 0)

		return devt_from_partuuid(name + 9, devt);

	if (strncmp(name, "PARTLABEL=", 10) == 0)

		return devt_from_partlabel(name + 10, devt);

	if (strncmp(name, "/dev/", 5) == 0)

		return devt_from_devname(name + 5, devt);

	return devt_from_devnum(name, devt);

}

EXPORT_SYMBOL_GPL(early_lookup_bdev);

#endif



static int __init root_dev_setup(char *line)

{

	strscpy(saved_root_name, line, sizeof(saved_root_name));