lib/fs: introduce new metric for Filesystem type name

This commit introduces a new metric to expose fs type for the provided path.

 For example:
```
vm_fs_info{path="/vmstorage-data", fs_type="xfs"}
```

 Path must be registered with new method `fs.RegisterPathFsMetrics`.

fixes https://github.com/VictoriaMetrics/VictoriaMetrics/issues/10482

app/vmagent/remotewrite/remotewrite.go

@@ -285,6 +285,7 @@ func initRemoteWriteCtxs(urls []string) {
 		rwctxs[i] = newRemoteWriteCtx(i, remoteWriteURL, sanitizedURL)
 		rwctxIdx[i] = i
 	}
+	fs.RegisterPathFsMetrics(*tmpDataPath)
 
 	if *shardByURL {
 		consistentHashNodes := make([]string, 0, len(urls))

app/vmstorage/main.go

@@ -180,6 +180,7 @@ func Init(resetCacheIfNeeded func(mrs []storage.MetricRow)) {
 		writeStorageMetrics(w, strg)
 	})
 	metrics.RegisterSet(storageMetrics)
+	fs.RegisterPathFsMetrics(*DataPath)
 }
 
 var storageMetrics *metrics.Set

docs/victoriametrics/changelog/CHANGELOG.md

@@ -31,6 +31,7 @@ See also [LTS releases](https://docs.victoriametrics.com/victoriametrics/lts-rel
 * FEATURE: [vmalert](https://docs.victoriametrics.com/victoriametrics/vmalert/): add `-rule.stripFilePath` to support stripping rule file paths in logs and all API responses, including /metrics. See [#5625](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5625).
 * FEATURE: [vmalert](https://docs.victoriametrics.com/victoriametrics/vmalert/): add `formatTime` template function for formatting a Unix timestamp using the provided layout. For example, `{{ now | formatTime "2006-01-02T15:04:05Z07:00" }}` returns the current time in RFC3339 format. See issue [#10624](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/10624). Thanks to @andriibeee for the contribution.
 * FEATURE: [vmagent](https://docs.victoriametrics.com/victoriametrics/vmagent/), [vmsingle](https://docs.victoriametrics.com/victoriametrics/single-server-victoriametrics/), `vminsert` in [VictoriaMetrics cluster](https://docs.victoriametrics.com/victoriametrics/cluster-victoriametrics/): add support for [Prometheus native histogram](https://prometheus.io/docs/specs/native_histograms/) during ingestion. See [#10743](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/10743).
+* FEATURE: [vmagent](https://docs.victoriametrics.com/victoriametrics/vmagent/), [vmsingle](https://docs.victoriametrics.com/victoriametrics/single-server-victoriametrics/), `vmselect` in [VictoriaMetrics cluster](https://docs.victoriametrics.com/victoriametrics/cluster-victoriametrics/) and `vmstorage` in [VictoriaMetrics cluster](https://docs.victoriametrics.com/victoriametrics/cluster-victoriametrics/): introduce the `vm_fs_info` metric. It exposes the filesystem type (e.g., ext4, xfs, nfs) used for `-*Path` related flags. See [#10482](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/10482).
 * FEATURE: [dashboards/vmagent](https://grafana.com/grafana/dashboards/12683): add `Kafka (Enterprise)` row with panels for monitoring traffic (bytes), messages in/out, producer and consumer errors. See [#10728](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/10728).
 
 * BUGFIX: [vmagent](https://docs.victoriametrics.com/victoriametrics/vmagent/) and [vmsingle](https://docs.victoriametrics.com/victoriametrics/single-server-victoriametrics/): properly obtain `__meta_hetzner_hcloud_location` and `__meta_hetzner_hcloud_location_network_zone` labels for [hetzner_sd_configs](https://docs.victoriametrics.com/victoriametrics/sd_configs/#hetzner_sd_configs). Hetzner changed discovery [API response](https://docs.hetzner.cloud/changelog#2025-12-16-phasing-out-datacenters) and returns `location` information from different field. See [#10909](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/10909). Thanks to @juliusrickert for contribution.

lib/fs/fs.go

@@ -13,6 +13,7 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/filestream"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fs/fsutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
+	"github.com/VictoriaMetrics/metrics"
 )
 
 var tmpFileNum atomicutil.Uint64
@@ -352,3 +353,8 @@ type diskSpaceEntry struct {
 func IsDirOrSymlink(de os.DirEntry) bool {
 	return de.IsDir() || (de.Type()&os.ModeSymlink == os.ModeSymlink)
 }
+
+// RegisterPathFsMetrics exposes filesystem information for the given path as metrics.
+func RegisterPathFsMetrics(path string) {
+	_ = metrics.GetOrCreateGauge(fmt.Sprintf(`vm_fs_info{path=%q, fs_type=%q}`, path, getFsType(path)), func() float64 { return 1 })
+}

lib/fs/fs_linux.go

@@ -0,0 +1,65 @@
+//go:build linux
+
+package fs
+
+import (
+	"golang.org/x/sys/unix"
+)
+
+type statfs_t = unix.Statfs_t
+
+func freeSpace(stat statfs_t) uint64 {
+	return uint64(stat.Bavail) * uint64(stat.Bsize)
+}
+
+// totalSpace returns the total capacity of the filesystem described by stat in bytes.
+func totalSpace(stat statfs_t) uint64 {
+	return uint64(stat.Blocks) * uint64(stat.Bsize)
+}
+
+func statfs(path string, stat *statfs_t) (err error) {
+	return unix.Statfs(path, stat)
+}
+
+// https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/magic.h
+var fsMagicNumberToName = map[int64]string{
+	0xEF53:     "ext2/ext3/ext4",
+	0xabba1974: "xenfs",
+	0x9123683E: "btrfs",
+	0x3434:     "nilfs",
+	0xF2F52010: "f2fs",
+	0xf995e849: "hpfs",
+	0x9660:     "isofs",
+	0x72b6:     "jffs2",
+	0x58465342: "xfs",
+	0x6165676C: "pstorefs",
+	0xde5e81e4: "efivarfs",
+	0x00c0ffee: "hostfs",
+	0x794c7630: "overlayfs",
+	0x65735546: "fuse",
+	0xca451a4e: "bcachefs",
+	0xadf5:     "adfs",
+	0xadff:     "affs",
+	0x5346414F: "afs",
+	0x0187:     "autofs",
+	0xf15f:     "ecryptfs",
+	0x414A53:   "efs",
+	0xE0F5E1E2: "erofs",
+	0x6969:     "nfs",
+	0xFF534D42: "cifs",
+	0x6c6f6f70: "binderfs",
+	0xBAD1DEA:  "futexfs",
+}
+
+func getFsType(path string) string {
+	var stat statfs_t
+	fsName := "unknown"
+	err := statfs(path, &stat)
+	if err != nil {
+		return fsName
+	}
+	if fsn, ok := fsMagicNumberToName[int64(stat.Type)]; ok {
+		fsName = fsn
+	}
+	return fsName
+}

lib/fs/fs_netbsd.go

@@ -18,3 +18,13 @@ func totalSpace(stat statfs_t) uint64 {
 func statfs(path string, buf *statfs_t) (err error) {
 	return unix.Statvfs(path, buf)
 }
+
+func getFsType(path string) string {
+	var stat statfs_t
+	err := statfs(path, &stat)
+	if err != nil {
+		return "unknown"
+	}
+
+	return unix.ByteSliceToString(stat.Fstypename[:])
+}

lib/fs/fs_nix.go

@@ -1,4 +1,4 @@
-//go:build linux || darwin || freebsd
+//go:build darwin || freebsd
 
 package fs
 
@@ -20,3 +20,13 @@ func totalSpace(stat statfs_t) uint64 {
 func statfs(path string, stat *statfs_t) (err error) {
 	return unix.Statfs(path, stat)
 }
+
+func getFsType(path string) string {
+	var stat statfs_t
+	err := statfs(path, &stat)
+	if err != nil {
+		return "unknown"
+	}
+
+	return unix.ByteSliceToString(stat.Fstypename[:])
+}

lib/fs/fs_openbsd.go

@@ -18,3 +18,7 @@ func totalSpace(stat statfs_t) uint64 {
 func statfs(path string, stat *statfs_t) (err error) {
 	return unix.Statfs(path, stat)
 }
+
+func getFsType(path string) string {
+	return "unknown"
+}

lib/fs/fs_windows.go

@@ -124,3 +124,7 @@ func newOverlapped() (*windows.Overlapped, error) {
 	}
 	return &windows.Overlapped{HEvent: event}, nil
 }
+
+func getFsType(_ string) string {
+	return "unknown"
+}