1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
|
// 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);
|
