Allow LVM output parsing to work for thin volumes

This patch modifies the LVM output parsing code to allow for an empty
list of physical devices, as is the case with thin LVM volumes.

Signed-off-by: Hrvoje Ribicic <riba@google.com>
Reviewed-by: Petr Pudlak <pudlak@google.com>

diff --git a/lib/storage/bdev.py b/lib/storage/bdev.py
index 4e21011..1ffef76 100644 (file)
--- a/lib/storage/bdev.py
+++ b/lib/storage/bdev.py
@@ -441,7 +441,15 @@ class LogicalVolume(base.BlockDev):
     """Parse one line of the lvs output used in L{_GetLvInfo}.
 
     """
-    elems = line.strip().rstrip(sep).split(sep)
+    elems = line.strip().split(sep)
+
+    # The previous iteration of code here assumed that LVM might put another
+    # separator to the right of the output. The PV info might be empty for
+    # thin volumes, so stripping off the separators might cut off the last
+    # empty element - do this instead.
+    if len(elems) == 7 and elems[-1] == "":
+      elems.pop()
+
     if len(elems) != 6:
       base.ThrowError("Can't parse LVS output, len(%s) != 6", str(elems))
 
@@ -466,12 +474,12 @@ class LogicalVolume(base.BlockDev):
       base.ThrowError("Can't parse the number of stripes: %s", err)
 
     pv_names = []
-    for pv in pvs.split(","):
-      m = re.match(cls._PARSE_PV_DEV_RE, pv)
-      if not m:
-        base.ThrowError("Can't parse this device list: %s", pvs)
-      pv_names.append(m.group(1))
-    assert len(pv_names) > 0
+    if pvs != "":
+      for pv in pvs.split(","):
+        m = re.match(cls._PARSE_PV_DEV_RE, pv)
+        if not m:
+          base.ThrowError("Can't parse this device list: %s", pvs)
+        pv_names.append(m.group(1))
 
     return (status, major, minor, pe_size, stripes, pv_names)
 

diff --git a/test/py/ganeti.storage.bdev_unittest.py b/test/py/ganeti.storage.bdev_unittest.py
index 819c940..d6ba9f8 100755 (executable)
--- a/test/py/ganeti.storage.bdev_unittest.py
+++ b/test/py/ganeti.storage.bdev_unittest.py
@@ -219,6 +219,8 @@ class TestLogicalVolume(unittest.TestCase):
       ("-wi-a-", 253, 7, 4096.00, 4, ["/dev/abc"]),
       ("-ri-a-", 253, 4, 4.00, 5, ["/dev/abc", "/dev/def"]),
       ("-wc-ao", 15, 18, 4096.00, 32, ["/dev/abc", "/dev/def", "/dev/ghi0"]),
+      # Physical devices might be missing with thin volumes
+      ("twc-ao", 15, 18, 4096.00, 32, []),
       ]
     for exp in true_out:
       for sep in "#;|":