diff options
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 4 | ||||
| -rw-r--r-- | block/Makefile | 2 | ||||
| -rw-r--r-- | block/early-lookup.c | 224 | ||||
| -rw-r--r-- | init/do_mounts.c | 219 |
4 files changed, 227 insertions, 222 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index a6bc31349cbb..911c54829c7c 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -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. diff --git a/block/Makefile b/block/Makefile index b31b05390749..46ada9dc8bbf 100644 --- a/block/Makefile +++ b/block/Makefile @@ -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 diff --git a/block/early-lookup.c b/block/early-lookup.c new file mode 100644 index 000000000000..9fc30d039508 --- /dev/null +++ b/block/early-lookup.c @@ -0,0 +1,224 @@ +// 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); diff --git a/init/do_mounts.c b/init/do_mounts.c index 0b36a5f39ee8..780546a6cbfb 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -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)); |