413 lines
12 KiB
Go
413 lines
12 KiB
Go
// Copyright 2019 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//go:build !nobtrfs
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// +build !nobtrfs
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package collector
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import (
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"fmt"
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"path"
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"strings"
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"syscall"
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dennwc "github.com/dennwc/btrfs"
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"github.com/go-kit/log"
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"github.com/go-kit/log/level"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/procfs/btrfs"
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)
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// A btrfsCollector is a Collector which gathers metrics from Btrfs filesystems.
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type btrfsCollector struct {
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fs btrfs.FS
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logger log.Logger
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}
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func init() {
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registerCollector("btrfs", defaultEnabled, NewBtrfsCollector)
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}
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// NewBtrfsCollector returns a new Collector exposing Btrfs statistics.
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func NewBtrfsCollector(logger log.Logger) (Collector, error) {
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fs, err := btrfs.NewFS(*sysPath)
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if err != nil {
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return nil, fmt.Errorf("failed to open sysfs: %w", err)
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}
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return &btrfsCollector{
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fs: fs,
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logger: logger,
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}, nil
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}
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// Update retrieves and exports Btrfs statistics.
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// It implements Collector.
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func (c *btrfsCollector) Update(ch chan<- prometheus.Metric) error {
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stats, err := c.fs.Stats()
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if err != nil {
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return fmt.Errorf("failed to retrieve Btrfs stats from procfs: %w", err)
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}
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ioctlStatsMap, err := c.getIoctlStats()
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if err != nil {
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level.Debug(c.logger).Log(
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"msg", "Error querying btrfs device stats with ioctl",
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"err", err)
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ioctlStatsMap = make(map[string]*btrfsIoctlFsStats)
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}
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for _, s := range stats {
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// match up procfs and ioctl info by filesystem UUID (without dashes)
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var fsUUID = strings.Replace(s.UUID, "-", "", -1)
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ioctlStats := ioctlStatsMap[fsUUID]
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c.updateBtrfsStats(ch, s, ioctlStats)
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}
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return nil
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}
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type btrfsIoctlFsDevStats struct {
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path string
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uuid string
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bytesUsed uint64
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totalBytes uint64
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// The error stats below match the following upstream lists:
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// https://github.com/dennwc/btrfs/blob/b3db0b2dedac3bf580f412034d77e0bf4b420167/btrfs.go#L132-L140
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// https://github.com/torvalds/linux/blob/70d605cbeecb408dd884b1f0cd3963eeeaac144c/include/uapi/linux/btrfs.h#L680-L692
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writeErrs uint64
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readErrs uint64
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flushErrs uint64
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corruptionErrs uint64
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generationErrs uint64
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}
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type btrfsIoctlFsStats struct {
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uuid string
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devices []btrfsIoctlFsDevStats
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}
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func (c *btrfsCollector) getIoctlStats() (map[string]*btrfsIoctlFsStats, error) {
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// Instead of introducing more ioctl calls to scan for all btrfs
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// filesystems re-use our mount point utils to find known mounts
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mountsList, err := mountPointDetails(c.logger)
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if err != nil {
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return nil, err
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}
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// Track devices we have successfully scanned, by device path.
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devicesDone := make(map[string]struct{})
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// Filesystems scann results by UUID.
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fsStats := make(map[string]*btrfsIoctlFsStats)
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for _, mount := range mountsList {
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if mount.fsType != "btrfs" {
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continue
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}
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if _, found := devicesDone[mount.device]; found {
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// We already found this filesystem by another mount point.
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continue
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}
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mountPath := rootfsFilePath(mount.mountPoint)
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fs, err := dennwc.Open(mountPath, true)
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if err != nil {
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// Failed to open this mount point, maybe we didn't have permission
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// maybe we'll find another mount point for this FS later.
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level.Debug(c.logger).Log(
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"msg", "Error inspecting btrfs mountpoint",
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"mountPoint", mountPath,
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"err", err)
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continue
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}
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defer fs.Close()
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fsInfo, err := fs.Info()
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if err != nil {
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// Failed to get the FS info for some reason,
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// perhaps it'll work with a different mount point
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level.Debug(c.logger).Log(
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"msg", "Error querying btrfs filesystem",
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"mountPoint", mountPath,
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"err", err)
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continue
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}
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fsID := fsInfo.FSID.String()
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if _, found := fsStats[fsID]; found {
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// We already found this filesystem by another mount point
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continue
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}
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deviceStats, err := c.getIoctlDeviceStats(fs, &fsInfo)
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if err != nil {
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level.Debug(c.logger).Log(
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"msg", "Error querying btrfs device stats",
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"mountPoint", mountPath,
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"err", err)
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continue
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}
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devicesDone[mount.device] = struct{}{}
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fsStats[fsID] = &btrfsIoctlFsStats{
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uuid: fsID,
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devices: deviceStats,
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}
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}
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return fsStats, nil
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}
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func (c *btrfsCollector) getIoctlDeviceStats(fs *dennwc.FS, fsInfo *dennwc.Info) ([]btrfsIoctlFsDevStats, error) {
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devices := make([]btrfsIoctlFsDevStats, 0, fsInfo.NumDevices)
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for i := uint64(0); i <= fsInfo.MaxID; i++ {
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deviceInfo, err := fs.GetDevInfo(i)
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if err != nil {
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if errno, ok := err.(syscall.Errno); ok && errno == syscall.ENODEV {
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// Device IDs do not consistently start at 0, nor are ranges contiguous, so we expect this.
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continue
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}
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return nil, err
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}
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deviceStats, err := fs.GetDevStats(i)
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if err != nil {
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return nil, err
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}
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devices = append(devices, btrfsIoctlFsDevStats{
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path: deviceInfo.Path,
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uuid: deviceInfo.UUID.String(),
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bytesUsed: deviceInfo.BytesUsed,
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totalBytes: deviceInfo.TotalBytes,
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writeErrs: deviceStats.WriteErrs,
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readErrs: deviceStats.ReadErrs,
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flushErrs: deviceStats.FlushErrs,
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corruptionErrs: deviceStats.CorruptionErrs,
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generationErrs: deviceStats.GenerationErrs,
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})
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if uint64(len(devices)) == fsInfo.NumDevices {
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break
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}
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}
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return devices, nil
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}
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// btrfsMetric represents a single Btrfs metric that is converted into a Prometheus Metric.
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type btrfsMetric struct {
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name string
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metricType prometheus.ValueType
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desc string
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value float64
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extraLabel []string
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extraLabelValue []string
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}
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// updateBtrfsStats collects statistics for one bcache ID.
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func (c *btrfsCollector) updateBtrfsStats(ch chan<- prometheus.Metric, s *btrfs.Stats, ioctlStats *btrfsIoctlFsStats) {
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const subsystem = "btrfs"
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// Basic information about the filesystem.
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devLabels := []string{"uuid"}
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// Retrieve the metrics.
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metrics := c.getMetrics(s, ioctlStats)
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// Convert all gathered metrics to Prometheus Metrics and add to channel.
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for _, m := range metrics {
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labels := append(devLabels, m.extraLabel...)
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desc := prometheus.NewDesc(
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prometheus.BuildFQName(namespace, subsystem, m.name),
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m.desc,
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labels,
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nil,
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)
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labelValues := []string{s.UUID}
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if len(m.extraLabelValue) > 0 {
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labelValues = append(labelValues, m.extraLabelValue...)
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}
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ch <- prometheus.MustNewConstMetric(
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desc,
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m.metricType,
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m.value,
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labelValues...,
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)
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}
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}
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// getMetrics returns metrics for the given Btrfs statistics.
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func (c *btrfsCollector) getMetrics(s *btrfs.Stats, ioctlStats *btrfsIoctlFsStats) []btrfsMetric {
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metrics := []btrfsMetric{
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{
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name: "info",
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desc: "Filesystem information",
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value: 1,
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metricType: prometheus.GaugeValue,
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extraLabel: []string{"label"},
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extraLabelValue: []string{s.Label},
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},
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{
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name: "global_rsv_size_bytes",
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desc: "Size of global reserve.",
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metricType: prometheus.GaugeValue,
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value: float64(s.Allocation.GlobalRsvSize),
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},
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}
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// Information about data, metadata and system data.
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metrics = append(metrics, c.getAllocationStats("data", s.Allocation.Data)...)
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metrics = append(metrics, c.getAllocationStats("metadata", s.Allocation.Metadata)...)
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metrics = append(metrics, c.getAllocationStats("system", s.Allocation.System)...)
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// Information about devices.
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if ioctlStats == nil {
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for n, dev := range s.Devices {
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metrics = append(metrics, btrfsMetric{
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name: "device_size_bytes",
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desc: "Size of a device that is part of the filesystem.",
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metricType: prometheus.GaugeValue,
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value: float64(dev.Size),
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extraLabel: []string{"device"},
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extraLabelValue: []string{n},
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})
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}
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return metrics
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}
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for _, dev := range ioctlStats.devices {
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// trim the path prefix from the device name so the value should match
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// the value used in the fallback branch above.
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// e.g. /dev/sda -> sda, /rootfs/dev/md1 -> md1
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_, device := path.Split(dev.path)
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extraLabels := []string{"device", "btrfs_dev_uuid"}
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extraLabelValues := []string{device, dev.uuid}
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metrics = append(metrics,
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btrfsMetric{
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name: "device_size_bytes",
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desc: "Size of a device that is part of the filesystem.",
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metricType: prometheus.GaugeValue,
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value: float64(dev.totalBytes),
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extraLabel: extraLabels,
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extraLabelValue: extraLabelValues,
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},
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// A bytes available metric is probably more useful than a
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// bytes used metric, because large numbers of bytes will
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// suffer from floating point representation issues
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// and we probably care more about the number when it's low anyway
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btrfsMetric{
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name: "device_unused_bytes",
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desc: "Unused bytes unused on a device that is part of the filesystem.",
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metricType: prometheus.GaugeValue,
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value: float64(dev.totalBytes - dev.bytesUsed),
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extraLabel: extraLabels,
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extraLabelValue: extraLabelValues,
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})
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errorLabels := append([]string{"type"}, extraLabels...)
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values := []uint64{
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dev.writeErrs,
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dev.readErrs,
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dev.flushErrs,
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dev.corruptionErrs,
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dev.generationErrs,
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}
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btrfsErrorTypeNames := []string{
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"write",
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"read",
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"flush",
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"corruption",
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"generation",
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}
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for i, errorType := range btrfsErrorTypeNames {
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metrics = append(metrics,
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btrfsMetric{
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name: "device_errors_total",
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desc: "Errors reported for the device",
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metricType: prometheus.CounterValue,
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value: float64(values[i]),
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extraLabel: errorLabels,
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extraLabelValue: append([]string{errorType}, extraLabelValues...),
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})
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}
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}
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return metrics
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}
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// getAllocationStats returns allocation metrics for the given Btrfs Allocation statistics.
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func (c *btrfsCollector) getAllocationStats(a string, s *btrfs.AllocationStats) []btrfsMetric {
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metrics := []btrfsMetric{
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{
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name: "reserved_bytes",
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desc: "Amount of space reserved for a data type",
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metricType: prometheus.GaugeValue,
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value: float64(s.ReservedBytes),
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extraLabel: []string{"block_group_type"},
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extraLabelValue: []string{a},
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},
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}
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// Add all layout statistics.
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for layout, stats := range s.Layouts {
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metrics = append(metrics, c.getLayoutStats(a, layout, stats)...)
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}
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return metrics
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}
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// getLayoutStats returns metrics for a data layout.
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func (c *btrfsCollector) getLayoutStats(a, l string, s *btrfs.LayoutUsage) []btrfsMetric {
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return []btrfsMetric{
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{
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name: "used_bytes",
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desc: "Amount of used space by a layout/data type",
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metricType: prometheus.GaugeValue,
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value: float64(s.UsedBytes),
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extraLabel: []string{"block_group_type", "mode"},
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extraLabelValue: []string{a, l},
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},
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{
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name: "size_bytes",
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desc: "Amount of space allocated for a layout/data type",
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metricType: prometheus.GaugeValue,
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value: float64(s.TotalBytes),
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extraLabel: []string{"block_group_type", "mode"},
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extraLabelValue: []string{a, l},
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},
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{
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name: "allocation_ratio",
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desc: "Data allocation ratio for a layout/data type",
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metricType: prometheus.GaugeValue,
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value: s.Ratio,
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extraLabel: []string{"block_group_type", "mode"},
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extraLabelValue: []string{a, l},
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},
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}
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}
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