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authorNikolaus Voss <nikolaus.voss@loewensteinmedical.de>2018-10-30 15:05:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-10-31 08:54:13 -0700
commitf027c34d844013d9d6c902af8fa01a82d6e5073d (patch)
tree46d4851a2f48ad45fb064ddd30c30c36362059cc /init/do_mounts.c
parent22ebb72b32606aa0f891e09de007be7d3d8effd1 (diff)
init/do_mounts.c: add root=PARTLABEL=<name> support
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>
Diffstat (limited to 'init/do_mounts.c')
-rw-r--r--init/do_mounts.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/init/do_mounts.c b/init/do_mounts.c
index e1c9afa9d8c9..a754e3ba9831 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -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