ceph-volume: single lvs call to speed up exclude_lvm_osd_devices

Cache all LVs from one global `lvs` call and use it in
`filter_lvm_osd_devices` to avoid repeated subprocesses and speed up
`ceph-volume generic activate` significantly.

Fixes: https://tracker.ceph.com/issues/74804
Signed-off-by: Guillaume Abrioux <gabrioux@ibm.com>

diff --git a/src/ceph-volume/ceph_volume/devices/raw/list.py b/src/ceph-volume/ceph_volume/devices/raw/list.py
index 135db33a0fba5a6608f756aec4459f0937c81151..7bc83fc417320aa7d5ce92051ec6aaf58728fe21 100644 (file)
--- a/src/ceph-volume/ceph_volume/devices/raw/list.py
+++ b/src/ceph-volume/ceph_volume/devices/raw/list.py
@@ -5,8 +5,6 @@ import argparse
 import json
 import logging
 from textwrap import dedent
-from concurrent.futures import ThreadPoolExecutor
-
 from ceph_volume import decorators, process
 from ceph_volume.util import disk
 from ceph_volume.api import lvm
@@ -58,6 +56,7 @@ class List(object):
         self.argv = argv
         self.info_devices: _List[Dict[str, str]] = []
         self.devices_to_scan: _List[str] = []
+        self._lvs_by_realpath: Dict[str, _List[Any]] = {}
 
     def exclude_invalid_devices(self, devices: _List[Dict[str, str]]) -> _List[Dict[str, str]]:
         return [
@@ -86,12 +85,25 @@ class List(object):
 
     def exclude_lvm_osd_devices(self) -> None:
         lvm_mappers = disk.get_lvm_mappers()
-        with ThreadPoolExecutor() as pool:
-            filtered_devices_to_scan = pool.map(
-                lambda device: self.filter_lvm_osd_devices(device, lvm_mappers),
-                self.devices_to_scan
-            )
-            self.devices_to_scan = [device for device in filtered_devices_to_scan if device is not None]
+        self._lvs_by_realpath = self._build_lvs_by_realpath()
+        self.devices_to_scan = [
+            device
+            for device in self.devices_to_scan
+            if self.filter_lvm_osd_devices(device, lvm_mappers) is not None
+        ]
+
+    def _build_lvs_by_realpath(self) -> Dict[str, _List[Any]]:
+        result: Dict[str, _List[Any]] = {}
+        try:
+            for lv in lvm.get_lvs():
+                try:
+                    rp = os.path.realpath(lv.lv_path)
+                    result.setdefault(rp, []).append(lv)
+                except OSError as e:
+                    logger.debug("Skipping LV %s: %s", lv.lv_path, e)
+        except RuntimeError as e:
+            logger.warning("Failed to list LVs while building LV-to-realpath map for raw device list: %s", e)
+        return result
 
     def filter_lvm_osd_devices(self, device: str, lvm_mappers: _List[str]) -> Optional[str]:
         real_path = os.path.realpath(device)
@@ -100,9 +112,7 @@ class List(object):
         if real_path not in lvm_mappers:
             return device
 
-        # It's an LV, so we need to check if it's a Ceph device
-        # This requires a subprocess call, but it's much lighter than Device()
-        lvs = lvm.get_lvs_from_path(device)
+        lvs = self._lvs_by_realpath.get(real_path, [])
         if lvs:
             # Check if any LV has ceph.osd_id tag (making it a Ceph device)
             for lv in lvs: