Add zfs_refcount command

Author: PaulZ-98

sdb/commands/zfs/zfs_refcount.py

@@ -0,0 +1,59 @@
+#
+# Copyright 2020 Datto, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+# pylint: disable=missing-docstring
+
+from typing import Iterable
+import drgn
+import sdb
+from sdb.commands.spl.spl_list import SPLList
+
+
+class Zfs_Refcount(sdb.PrettyPrinter):
+    names = ["zfs_refcount"]
+    input_type = "zfs_refcount_t *"
+    output_type = "zfs_refcount_t *"
+
+    @staticmethod
+    def print_ref(obj: drgn.Object) -> None:
+        ptr = int(obj.ref_holder)
+        c = sdb.create_object("char *", ptr)
+        try:
+            s = c.string_().decode("utf-8")
+        except UnicodeDecodeError:
+            s = ""
+        print(f"{hex(ptr)}   {s} ")
+
+    def pretty_print(self, objs: Iterable[drgn.Object]) -> None:
+        for zr in objs:
+            # handle the lack of rc_tracked in non-debug zfs build
+            tracked = 0
+            try:
+                tracked = zr.rc_tracked
+            except AttributeError:
+                pass
+            print(f"zfs_recount_t at {hex(zr)} has {int(zr.rc_count)} "
+                  f"current holds tracked={int(tracked)}")
+            if tracked:
+                ref_list = zr.rc_list
+                list_addr = ref_list.address_of_()
+                refs = sdb.execute_pipeline(
+                    [list_addr],
+                    [SPLList(), sdb.Cast(["reference_t *"])],
+                )
+
+                for ref in refs:
+                    Zfs_Refcount.print_ref(ref)

tests/integration/data/regression_output/zfs/spa |member spa_refcount | zfs_refcount

@@ -0,0 +1,3 @@
+zfs_recount_t at 0xffffa0894e7223c8 has 12 current holds tracked=0
+zfs_recount_t at 0xffffa089413ba3c8 has 15 current holds tracked=0
+zfs_recount_t at 0xffffa08955c463c8 has 39 current holds tracked=0

tests/integration/test_zfs_generic.py

@@ -61,6 +61,9 @@
     "spa data | vdev | metaslab | filter 'obj.ms_loaded == 1' | head 1 | member ms_sm.sm_phys.smp_histogram | zhist",
     "spa data | vdev | metaslab | filter 'obj.ms_loaded == 1' | head 1 | member ms_sm.sm_phys.smp_histogram | zhist 9",
     "spa data | vdev | metaslab | filter 'obj.ms_loaded == 1' | head 1 | member ms_allocatable.rt_histogram | zhist",
+
+    # refcount
+    "spa |member spa_refcount | zfs_refcount",
 ] # yapf: disable