From b9269151a4376c64f7c099a9d18cdec391867f1a Mon Sep 17 00:00:00 2001
From: Anis Eleuch <vadmeste@users.noreply.github.com>
Date: Wed, 6 Sep 2023 20:37:57 +0100
Subject: [PATCH] fix: drive rotational calculation status for partitions
 (#17986)

Fix drive rotational calculation status

If a MinIO drive path is mounted to a partition and not a real disk,
getting the rotational status would fail because Linux does not expose
that status to partition; In other words,
/sys/block/drive-partition-name/queue/rotational does not exist;

To fix the issue, the code will search for the rotational status of the
disk that hosts the partition, and this can be calculated from the
real path of /sys/class/block/<drive-partition-name>
---
 internal/disk/stat_linux.go | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/internal/disk/stat_linux.go b/internal/disk/stat_linux.go
index 0bf1e0d44..ce08ea940 100644
--- a/internal/disk/stat_linux.go
+++ b/internal/disk/stat_linux.go
@@ -24,6 +24,7 @@ import (
 	"bufio"
 	"fmt"
 	"os"
+	"path/filepath"
 	"strconv"
 	"strings"
 	"syscall"
@@ -71,23 +72,36 @@ func GetInfo(path string, firstTime bool) (info Info, err error) {
 	if firstTime {
 		bfs, err := blockdevice.NewDefaultFS()
 		if err == nil {
+			devName := ""
 			diskstats, _ := bfs.ProcDiskstats()
 			for _, dstat := range diskstats {
 				// ignore all loop devices
 				if strings.HasPrefix(dstat.DeviceName, "loop") {
 					continue
 				}
-				qst, err := bfs.SysBlockDeviceQueueStats(dstat.DeviceName)
-				if err != nil {
-					continue
-				}
-				rot := qst.Rotational == 1 // Rotational is '1' if the device is HDD
 				if dstat.MajorNumber == info.Major && dstat.MinorNumber == info.Minor {
-					info.Name = dstat.DeviceName
-					info.Rotational = &rot
+					devName = dstat.DeviceName
 					break
 				}
 			}
+			if devName != "" {
+				info.Name = devName
+				qst, err := bfs.SysBlockDeviceQueueStats(devName)
+				if err != nil { // Mostly not found error
+					// Check if there is a parent device:
+					//   e.g. if the mount is based on /dev/nvme0n1p1, let's calculate the
+					//        real device name (nvme0n1) to get its sysfs information
+					parentDevPath, e := os.Readlink("/sys/class/block/" + devName)
+					if e == nil {
+						parentDev := filepath.Base(filepath.Dir(parentDevPath))
+						qst, err = bfs.SysBlockDeviceQueueStats(parentDev)
+					}
+				}
+				if err == nil {
+					rot := qst.Rotational == 1 // Rotational is '1' if the device is HDD
+					info.Rotational = &rot
+				}
+			}
 		}
 	}