Recurse block device stacking hierarchies

Turn LEDs on or off depending on their existence at the bottom of in block
device stacks.  This works with pretty much any hierarchy (RAID, LVM, DM, etc)
because the kernel tracks block device stacking dependencies in
/sys/block/<dev>/slaves/* (which can be seen as a tree using the tool `lsblk`).

For example:
	] grep md9 /proc/mdstat
	md9 : active raid5 sdg[0] sde[6] sdj[4] sdk[3] sdf[2] sdl[1]

	] encled md9
	0:0:18:0/Slot11	sde	fault_off	locate_off
	0:0:18:0/Slot08	sdf	fault_off	locate_off
	0:0:18:0/Slot06	sdg	fault_off	locate_off
	0:0:18:0/Slot10	sdj	fault_off	locate_off
	0:0:18:0/Slot09	sdk	fault_off	locate_off
	0:0:18:0/Slot07	sdl	fault_off	locate_off

	] encled md9 locate
	] encled md9
	0:0:18:0/Slot11	sde	fault_off	 LOCATE_ON
	0:0:18:0/Slot08	sdf	fault_off	 LOCATE_ON
	0:0:18:0/Slot06	sdg	fault_off	 LOCATE_ON
	0:0:18:0/Slot10	sdj	fault_off	 LOCATE_ON
	0:0:18:0/Slot09	sdk	fault_off	 LOCATE_ON
	0:0:18:0/Slot07	sdl	fault_off	 LOCATE_ON

In the more complex stack shown below, /dev/bcache0 is backed by /dev/md125
and /dev/md126.  Now encled can find the referenced devices at any point in the
stack:

	] encled md125
	0:0:18:0/Slot03	sdh	fault_off	locate_off
	0:0:18:0/Slot02	sdc	fault_off	locate_off

	] encled md126
	0:0:18:0/Slot01	sdb	fault_off	locate_off
	0:0:18:0/Slot00	sdi	fault_off	locate_off

	] encled bcache0
	0:0:18:0/Slot03	sdh	fault_off	locate_off
	0:0:18:0/Slot01	sdb	fault_off	locate_off
	0:0:18:0/Slot02	sdc	fault_off	locate_off
	0:0:18:0/Slot00	sdi	fault_off	locate_off

Signed-off-by: Eric Wheeler <[email protected]>

Author: Eric Wheeler

encled

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 import os
 import sys
+import re
 
 HELP = """
 
@@ -30,6 +31,13 @@ HELP = """
     encled sda locate - enable 'locate' for slot with sda block device
     encled /dev/sdbz fault - enable fault indicator slot with sdbz block device
 
+    Recurse block device stacking hierarchies:
+        encled bcache0 locate - locate all disks used by /dev/bcache0
+        encled md0            - list all disks that are RAID members of /dev/md0
+        encled /dev/vg0/lv    - list all disks that back the logical volume 'vg0/lv'
+        encled /dev/vg0/lv    - list all disks that back the logical volume 'vg0/lv'
+        encled /dev/mapper/myluks - list all disks that back an encrypted volume
+
 """
 
 CLASS = '/sys/class/enclosure/'
@@ -153,6 +161,38 @@ def list_all():
             devlist.append((e, s, path, status))
     return devlist
 
+# Recursively find SCSI devices in block device stacking hierarchies
+# by referencing /sys/block/<dev>/slaves/*
+def find_parent_devs(dev_names):
+    global depth
+
+    new_names = []
+    for dev_path in dev_names:
+        # Read symlinks, like from /dev/mapper/foo:
+        if os.path.islink(dev_path):
+            dev_path = os.readlink(dev_path)
+
+        # Use basename, we only need the name not the path:
+        dev_name = os.path.basename(dev_path)
+
+        # Strip partition numbers:
+        dev_name = re.sub('^(sd[a-z]+)\d*$', lambda x: x.group(1), dev_name)
+
+        slave_path = '/sys/block/' + dev_name + '/slaves/'
+        if re.match('^sd[a-z]+$', dev_name):
+            new_names.append(dev_name)
+        elif os.path.exists(slave_path):
+            new_names += find_parent_devs(os.listdir(slave_path))
+
+    dev_names += new_names
+
+    # Only return SCSI devices:
+    sd = []
+    for dev in dev_names:
+        if re.match('^sd[a-z]+$', dev):
+            sd.append(dev)
+
+    return set(sd)
 
 def main(argv):
     if len(argv) > 1 and argv[1] in ('--help', '-h', '-help', '/?', '?', 'help', '-v', '--version', '-V'):
@@ -164,6 +204,7 @@ def main(argv):
         return(-1)
 
     devlist = list_all()
+    devs = []
     if len(argv) < 2:
         if not devlist:
             print ("No enclosure devices found")
@@ -190,29 +231,30 @@ def main(argv):
             if result: return(result)
         return(0)
 
-    if 'sd' in argv[1] or '/dev' in argv[1]:
-        name = argv[1].lower().split('/')[-1]
-        for d in devlist:
-            if(d[3][0] == name):
-                dev = d
-                break
-        else:
-            print(f"encled: Unable to find device {name} in enclosure slots. (note: on-board SATA ports are not supported)")
-            return(-1)
-
-    elif '/' in argv[1]:
+    if re.match('^\d+:\d+:\d+:\d+/Slot\d+$', argv[1]):
         (enc, slot) = argv[1].split('/')
         path = find_name(enc, slot)
         dev = (enc, slot, path, get_status(path))
+        devs.append(dev)
+        if not len(devs):
+            print ("encled: Incorrect enclosure/slot  or device syntax")
+            print (HELP)
+            return(-1)
     else:
-        print ("encled: Incorrect enclosure/slot  or device syntax")
-        print (HELP)
-        return(-1)
+        names = find_parent_devs([ argv[1] ])
+        for d in devlist:
+            if(d[3][0] in names):
+                devs.append(d)
+        if not len(devs):
+            print(f"encled: Unable to find device {argv[1]} in enclosure slots. (note: on-board SATA ports are not supported)")
+            return(-1)
 
-    if len(argv) < 3:
-        print_status(dev[0], dev[1], dev[3])
-    else:
-        set_status(dev[2], argv[2])
+
+    for dev in devs:
+        if len(argv) < 3:
+            print_status(dev[0], dev[1], dev[3])
+        else:
+            set_status(dev[2], argv[2])
 
 
 if __name__ == '__main__':