317 lines
8.4 KiB
C
317 lines
8.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Code for looking up block devices in the early boot code before mounting the
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* root file system.
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*/
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#include <linux/blkdev.h>
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#include <linux/ctype.h>
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struct uuidcmp {
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const char *uuid;
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int len;
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};
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/**
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* match_dev_by_uuid - callback for finding a partition using its uuid
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* @dev: device passed in by the caller
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* @data: opaque pointer to the desired struct uuidcmp to match
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*
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* Returns 1 if the device matches, and 0 otherwise.
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*/
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static int __init match_dev_by_uuid(struct device *dev, const void *data)
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{
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struct block_device *bdev = dev_to_bdev(dev);
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const struct uuidcmp *cmp = data;
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if (!bdev->bd_meta_info ||
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strncasecmp(cmp->uuid, bdev->bd_meta_info->uuid, cmp->len))
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return 0;
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return 1;
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}
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/**
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* devt_from_partuuid - looks up the dev_t of a partition by its UUID
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* @uuid_str: char array containing ascii UUID
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* @devt: dev_t result
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*
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* The function will return the first partition which contains a matching
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* UUID value in its partition_meta_info struct. This does not search
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* by filesystem UUIDs.
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*
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* If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be
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* extracted and used as an offset from the partition identified by the UUID.
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*
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* Returns 0 on success or a negative error code on failure.
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*/
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static int __init devt_from_partuuid(const char *uuid_str, dev_t *devt)
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{
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struct uuidcmp cmp;
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struct device *dev = NULL;
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int offset = 0;
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char *slash;
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cmp.uuid = uuid_str;
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slash = strchr(uuid_str, '/');
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/* Check for optional partition number offset attributes. */
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if (slash) {
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char c = 0;
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/* Explicitly fail on poor PARTUUID syntax. */
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if (sscanf(slash + 1, "PARTNROFF=%d%c", &offset, &c) != 1)
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goto out_invalid;
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cmp.len = slash - uuid_str;
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} else {
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cmp.len = strlen(uuid_str);
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}
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if (!cmp.len)
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goto out_invalid;
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dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid);
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if (!dev)
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return -ENODEV;
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if (offset) {
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/*
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* Attempt to find the requested partition by adding an offset
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* to the partition number found by UUID.
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*/
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*devt = part_devt(dev_to_disk(dev),
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dev_to_bdev(dev)->bd_partno + offset);
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} else {
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*devt = dev->devt;
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}
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put_device(dev);
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return 0;
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out_invalid:
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pr_err("VFS: PARTUUID= is invalid.\n"
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"Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
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return -EINVAL;
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}
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/**
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* match_dev_by_label - callback for finding a partition using its label
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* @dev: device passed in by the caller
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* @data: opaque pointer to the label to match
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*
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* Returns 1 if the device matches, and 0 otherwise.
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*/
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static int __init match_dev_by_label(struct device *dev, const void *data)
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{
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struct block_device *bdev = dev_to_bdev(dev);
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const char *label = data;
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if (!bdev->bd_meta_info || strcmp(label, bdev->bd_meta_info->volname))
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return 0;
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return 1;
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}
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static int __init devt_from_partlabel(const char *label, dev_t *devt)
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{
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struct device *dev;
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dev = class_find_device(&block_class, NULL, label, &match_dev_by_label);
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if (!dev)
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return -ENODEV;
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*devt = dev->devt;
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put_device(dev);
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return 0;
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}
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static dev_t __init blk_lookup_devt(const char *name, int partno)
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{
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dev_t devt = MKDEV(0, 0);
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struct class_dev_iter iter;
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struct device *dev;
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class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
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while ((dev = class_dev_iter_next(&iter))) {
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struct gendisk *disk = dev_to_disk(dev);
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if (strcmp(dev_name(dev), name))
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continue;
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if (partno < disk->minors) {
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/* We need to return the right devno, even
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* if the partition doesn't exist yet.
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*/
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devt = MKDEV(MAJOR(dev->devt),
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MINOR(dev->devt) + partno);
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} else {
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devt = part_devt(disk, partno);
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if (devt)
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break;
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}
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}
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class_dev_iter_exit(&iter);
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return devt;
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}
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static int __init devt_from_devname(const char *name, dev_t *devt)
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{
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int part;
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char s[32];
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char *p;
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if (strlen(name) > 31)
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return -EINVAL;
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strcpy(s, name);
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for (p = s; *p; p++) {
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if (*p == '/')
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*p = '!';
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}
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*devt = blk_lookup_devt(s, 0);
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if (*devt)
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return 0;
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/*
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* Try non-existent, but valid partition, which may only exist after
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* opening the device, like partitioned md devices.
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*/
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while (p > s && isdigit(p[-1]))
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p--;
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if (p == s || !*p || *p == '0')
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return -ENODEV;
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/* try disk name without <part number> */
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part = simple_strtoul(p, NULL, 10);
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*p = '\0';
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*devt = blk_lookup_devt(s, part);
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if (*devt)
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return 0;
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/* try disk name without p<part number> */
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if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
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return -ENODEV;
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p[-1] = '\0';
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*devt = blk_lookup_devt(s, part);
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if (*devt)
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return 0;
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return -ENODEV;
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}
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static int __init devt_from_devnum(const char *name, dev_t *devt)
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{
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unsigned maj, min, offset;
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char *p, dummy;
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if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2 ||
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sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3) {
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*devt = MKDEV(maj, min);
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if (maj != MAJOR(*devt) || min != MINOR(*devt))
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return -EINVAL;
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} else {
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*devt = new_decode_dev(simple_strtoul(name, &p, 16));
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if (*p)
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return -EINVAL;
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}
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return 0;
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}
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/*
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* Convert a name into device number. We accept the following variants:
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*
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* 1) <hex_major><hex_minor> device number in hexadecimal represents itself
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* no leading 0x, for example b302.
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* 3) /dev/<disk_name> represents the device number of disk
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* 4) /dev/<disk_name><decimal> represents the device number
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* of partition - device number of disk plus the partition number
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* 5) /dev/<disk_name>p<decimal> - same as the above, that form is
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* used when disk name of partitioned disk ends on a digit.
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* 6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
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* unique id of a partition if the partition table provides it.
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* The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
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* partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
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* filled hex representation of the 32-bit "NT disk signature", and PP
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* is a zero-filled hex representation of the 1-based partition number.
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* 7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
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* a partition with a known unique id.
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* 8) <major>:<minor> major and minor number of the device separated by
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* a colon.
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* 9) PARTLABEL=<name> with name being the GPT partition label.
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* MSDOS partitions do not support labels!
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*
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* If name doesn't have fall into the categories above, we return (0,0).
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* block_class is used to check if something is a disk name. If the disk
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* name contains slashes, the device name has them replaced with
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* bangs.
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*/
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int __init early_lookup_bdev(const char *name, dev_t *devt)
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{
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if (strncmp(name, "PARTUUID=", 9) == 0)
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return devt_from_partuuid(name + 9, devt);
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if (strncmp(name, "PARTLABEL=", 10) == 0)
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return devt_from_partlabel(name + 10, devt);
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if (strncmp(name, "/dev/", 5) == 0)
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return devt_from_devname(name + 5, devt);
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return devt_from_devnum(name, devt);
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}
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static char __init *bdevt_str(dev_t devt, char *buf)
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{
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if (MAJOR(devt) <= 0xff && MINOR(devt) <= 0xff) {
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char tbuf[BDEVT_SIZE];
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snprintf(tbuf, BDEVT_SIZE, "%02x%02x", MAJOR(devt), MINOR(devt));
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snprintf(buf, BDEVT_SIZE, "%-9s", tbuf);
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} else
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snprintf(buf, BDEVT_SIZE, "%03x:%05x", MAJOR(devt), MINOR(devt));
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return buf;
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}
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/*
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* print a full list of all partitions - intended for places where the root
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* filesystem can't be mounted and thus to give the victim some idea of what
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* went wrong
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*/
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void __init printk_all_partitions(void)
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{
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struct class_dev_iter iter;
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struct device *dev;
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class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
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while ((dev = class_dev_iter_next(&iter))) {
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struct gendisk *disk = dev_to_disk(dev);
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struct block_device *part;
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char devt_buf[BDEVT_SIZE];
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unsigned long idx;
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/*
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* Don't show empty devices or things that have been
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* suppressed
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*/
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if (get_capacity(disk) == 0 || (disk->flags & GENHD_FL_HIDDEN))
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continue;
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/*
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* Note, unlike /proc/partitions, I am showing the numbers in
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* hex - the same format as the root= option takes.
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*/
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rcu_read_lock();
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xa_for_each(&disk->part_tbl, idx, part) {
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if (!bdev_nr_sectors(part))
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continue;
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printk("%s%s %10llu %pg %s",
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bdev_is_partition(part) ? " " : "",
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bdevt_str(part->bd_dev, devt_buf),
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bdev_nr_sectors(part) >> 1, part,
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part->bd_meta_info ?
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part->bd_meta_info->uuid : "");
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if (bdev_is_partition(part))
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printk("\n");
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else if (dev->parent && dev->parent->driver)
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printk(" driver: %s\n",
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dev->parent->driver->name);
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else
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printk(" (driver?)\n");
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}
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rcu_read_unlock();
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}
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class_dev_iter_exit(&iter);
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}
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