[PATCH 2/6] common: factor out a _bdev_disk_name helper

[Christoph Hellwig <hch@lst.de>]

This will be reused to look for the integrity subdirectory soon.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 common/rc | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/common/rc b/common/rc
index 8add0eedf942..2fa7ddebd8fd 100644
--- a/common/rc
+++ b/common/rc
@@ -5233,28 +5233,35 @@ _sysfs_dev()
 	echo /sys/dev/block/$maj:$min
 }
 
-# Get the sysfs queue path for a block device, handling partitions correctly.
-_sysfs_queue_path()
+#
+# Get the name for the main disk block device given an arbitrary blockdevice
+# /dev/ entry
+#
+_bdev_disk_name()
 {
-	local dev parent
-	dev=$(_short_dev "$1")
+	local dev=$(_short_dev "$1")
 
 	# For partitions, queue details are in the parent device's sysfs dir
 	if [ -e "/sys/class/block/$dev/partition" ]; then
-		parent=$(basename "$(readlink -f /sys/class/block/$dev/..)")
-	else
-		parent="$dev"
+		dev=$(basename "$(readlink -f /sys/class/block/$dev/..)")
 	fi
 
-	local queue_path="/sys/block/$parent/queue"
+	echo "$dev"
+}
+
+# Get the sysfs queue path for a block device, handling partitions correctly.
+_sysfs_queue_path()
+{
+	local disk=$(_bdev_disk_name "$1")
+	local queue_path="/sys/block/$disk/queue"
 
 	# Verify the path exists before returning
 	if [ -e "$queue_path" ]; then
 		echo "$queue_path"
 		return 0
-	else
-		return 1
 	fi
+
+	return 1
 }
 
 # Get the minimum block size of a file.  Usually this is the
-- 
2.53.0