init/do_mounts.c: add root=PARTLABEL=<name> support (f027c34d) · Commits · 戴 / test

Support referencing the root partition label from GPT as argument to the root= option on the kernel command line in analogy to referencing the partition uuid as root=PARTUUID=<uuid>. Specifying the partition label instead of the uuid is often much easier, e.g. in embedded environments when there is an A/B rootfs partition scheme for interruptible firmware updates (i.e. rootfsA/ rootfsB). The partition label can be queried with the blkid command. Link: http://lkml.kernel.org/r/20180822060904.828E510665E@pc-niv.weinmann.com Signed-off-by:

Nikolaus Voss <nikolaus.voss@loewensteinmedical.de> Reviewed-by:

Andrew Morton <akpm@linux-foundation.org> Cc: Dominik Brodowski <linux@dominikbrodowski.net> Cc: Sasha Levin <Alexander.Levin@microsoft.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

init/do_mounts.c

+31 −0

Original line number	Diff line number	Diff line
		@@ -167,6 +167,24 @@ done:
		}
		return res;
		}

		/**
		* 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)
		{
		const char *label = data;
		struct hd_struct *part = dev_to_part(dev);

		if (part->info && !strcmp(label, part->info->volname))
		return 1;

		return 0;
		}
		#endif

		/*
		@@ -190,6 +208,8 @@ done:
		* 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
		@@ -211,6 +231,17 @@ dev_t name_to_dev_t(const char *name)
		if (!res)
		goto fail;
		goto done;
		} else if (strncmp(name, "PARTLABEL=", 10) == 0) {
		struct device *dev;

		dev = class_find_device(&block_class, NULL, name + 10,
		&match_dev_by_label);
		if (!dev)
		goto fail;

		res = dev->devt;
		put_device(dev);
		goto done;
		}
		#endif

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