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.
Signed-off-by: Nikolaus Voss <nikolaus.v...@loewensteinmedical.de>
---
init/do_mounts.c | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/init/do_mounts.c b/init/do_mounts.c
index 2c71dabe5626..239b5104cff0 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -177,6 +177,24 @@ static dev_t devt_from_partuuid(const char *uuid_str)
}
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
/*
@@ -200,6 +218,8 @@ static dev_t devt_from_partuuid(const char *uuid_str)
* 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
@@ -221,6 +241,17 @@ 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
--
2.17.1
