init bcachefs support (#750)

Signed-off-by: Ananth Bhaskararaman <antsub@gmail.com>

Author: ananthb

bcachefs/bcachefs.go

@@ -0,0 +1,63 @@
+// Copyright The Prometheus Authors
+// 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.
+
+// Package bcachefs provides access to statistics exposed by Bcachefs filesystems.
+package bcachefs
+
+// Stats contains statistics for a single Bcachefs filesystem.
+type Stats struct {
+	UUID                string
+	BtreeCacheSizeBytes uint64
+
+	Compression map[string]CompressionStats
+	Errors      map[string]ErrorStats
+	Counters    map[string]CounterStats
+	BtreeWrites map[string]BtreeWriteStats
+	Devices     map[string]*DeviceStats
+}
+
+// CompressionStats contains compression statistics for a specific algorithm.
+type CompressionStats struct {
+	CompressedBytes        uint64
+	UncompressedBytes      uint64
+	AverageExtentSizeBytes uint64
+}
+
+// ErrorStats contains error count and timestamp for a specific error type.
+type ErrorStats struct {
+	Count     uint64
+	Timestamp uint64
+}
+
+// CounterStats contains counter values since mount and since filesystem creation.
+type CounterStats struct {
+	SinceMount              uint64
+	SinceFilesystemCreation uint64
+}
+
+// BtreeWriteStats contains btree write statistics for a specific type.
+type BtreeWriteStats struct {
+	Count     uint64
+	SizeBytes uint64
+}
+
+// DeviceStats contains statistics for a Bcachefs device.
+type DeviceStats struct {
+	Label           string
+	State           string
+	BucketSizeBytes uint64
+	Buckets         uint64
+	Durability      uint64
+	IODone          map[string]map[string]uint64
+	IOErrors        map[string]uint64
+}