nvme: Parse NVMe namespace details (#765)

* add nvme namespace details to NVMe devices.

---------

Signed-off-by: Shashwat Hiregoudar <shashwathiregoudar@gmail.com>

Author: ShashwatHiregoudar

sysfs/class_nvme.go

@@ -19,20 +19,37 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"regexp"
+	"strconv"
 
 	"github.com/prometheus/procfs/internal/util"
 )
 
 const nvmeClassPath = "class/nvme"
 
+var nvmeNamespacePattern = regexp.MustCompile(`nvme\d+c\d+n(\d+)`)
+
+// NVMeNamespace contains info from files in /sys/class/nvme/<device>/<namespace>.
+type NVMeNamespace struct {
+	ID               string // namespace ID extracted from directory name
+	UsedBlocks       uint64 // from nuse file (blocks used)
+	SizeBlocks       uint64 // from size file (total blocks)
+	LogicalBlockSize uint64 // from queue/logical_block_size file
+	ANAState         string // from ana_state file
+	UsedBytes        uint64 // calculated: UsedBlocks * LogicalBlockSize
+	SizeBytes        uint64 // calculated: SizeBlocks * LogicalBlockSize
+	CapacityBytes    uint64 // calculated: SizeBlocks * LogicalBlockSize
+}
+
 // NVMeDevice contains info from files in /sys/class/nvme for a single NVMe device.
 type NVMeDevice struct {
 	Name             string
-	Serial           string // /sys/class/nvme/<Name>/serial
-	Model            string // /sys/class/nvme/<Name>/model
-	State            string // /sys/class/nvme/<Name>/state
-	FirmwareRevision string // /sys/class/nvme/<Name>/firmware_rev
-	ControllerID     string // /sys/class/nvme/<Name>/cntlid
+	Serial           string          // /sys/class/nvme/<Name>/serial
+	Model            string          // /sys/class/nvme/<Name>/model
+	State            string          // /sys/class/nvme/<Name>/state
+	FirmwareRevision string          // /sys/class/nvme/<Name>/firmware_rev
+	ControllerID     string          // /sys/class/nvme/<Name>/cntlid
+	Namespaces       []NVMeNamespace // NVMe namespaces for this device
 }
 
 // NVMeClass is a collection of every NVMe device in /sys/class/nvme.
@@ -67,6 +84,7 @@ func (fs FS) parseNVMeDevice(name string) (*NVMeDevice, error) {
 	path := fs.sys.Path(nvmeClassPath, name)
 	device := NVMeDevice{Name: name}
 
+	// Parse device-level attributes
 	for _, f := range [...]string{"firmware_rev", "model", "serial", "state", "cntlid"} {
 		name := filepath.Join(path, f)
 		value, err := util.SysReadFile(name)
@@ -88,5 +106,68 @@ func (fs FS) parseNVMeDevice(name string) (*NVMeDevice, error) {
 		}
 	}
 
+	// Parse namespaces - read directory and filter using regex
+	dirs, err := os.ReadDir(path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to list NVMe namespaces at %q: %w", path, err)
+	}
+
+	var namespaces []NVMeNamespace
+
+	for _, d := range dirs {
+		// Use regex to identify namespace directories and extract namespace ID
+		match := nvmeNamespacePattern.FindStringSubmatch(d.Name())
+		if len(match) < 2 {
+			// Skip if not a namespace directory
+			continue
+		}
+		nsid := match[1]
+		namespacePath := filepath.Join(path, d.Name())
+
+		namespace := NVMeNamespace{
+			ID:       nsid,
+			ANAState: "unknown", // Default value
+		}
+
+		// Parse namespace attributes using the same approach as device attributes
+		for _, f := range [...]string{"nuse", "size", "queue/logical_block_size", "ana_state"} {
+			filePath := filepath.Join(namespacePath, f)
+			value, err := util.SysReadFile(filePath)
+			if err != nil {
+				if f == "ana_state" {
+					// ana_state may not exist, skip silently
+					continue
+				}
+				return nil, fmt.Errorf("failed to read file %q: %w", filePath, err)
+			}
+
+			switch f {
+			case "nuse":
+				if val, parseErr := strconv.ParseUint(value, 10, 64); parseErr == nil {
+					namespace.UsedBlocks = val
+				}
+			case "size":
+				if val, parseErr := strconv.ParseUint(value, 10, 64); parseErr == nil {
+					namespace.SizeBlocks = val
+				}
+			case "queue/logical_block_size":
+				if val, parseErr := strconv.ParseUint(value, 10, 64); parseErr == nil {
+					namespace.LogicalBlockSize = val
+				}
+			case "ana_state":
+				namespace.ANAState = value
+			}
+		}
+
+		// Calculate derived values
+		namespace.UsedBytes = namespace.UsedBlocks * namespace.LogicalBlockSize
+		namespace.SizeBytes = namespace.SizeBlocks * namespace.LogicalBlockSize
+		namespace.CapacityBytes = namespace.SizeBlocks * namespace.LogicalBlockSize
+
+		namespaces = append(namespaces, namespace)
+	}
+
+	device.Namespaces = namespaces
+
 	return &device, nil
 }