From ac3a19138ae43ce66393d5cf2cccbe504b042354 Mon Sep 17 00:00:00 2001
From: Harshavardhana <harsha@minio.io>
Date: Mon, 25 Sep 2023 08:26:29 -0700
Subject: [PATCH] fix: set scanning details locally to avoid cached values
 (#18092)

atomic variable results such as scanning must not use
cached values, instead rely on real-time information.
---
 cmd/storage-rest-client.go | 11 ++++++++++-
 cmd/xl-storage.go          |  6 +++++-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/cmd/storage-rest-client.go b/cmd/storage-rest-client.go
index fa3244650..3b18f88be 100644
--- a/cmd/storage-rest-client.go
+++ b/cmd/storage-rest-client.go
@@ -30,6 +30,7 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/minio/madmin-go/v3"
@@ -134,6 +135,8 @@ func toStorageErr(err error) error {
 
 // Abstracts a remote disk.
 type storageRESTClient struct {
+	scanning int32
+
 	endpoint   Endpoint
 	restClient *rest.Client
 	diskID     string
@@ -207,6 +210,9 @@ func (client *storageRESTClient) Healing() *healingTracker {
 }
 
 func (client *storageRESTClient) NSScanner(ctx context.Context, cache dataUsageCache, updates chan<- dataUsageEntry, scanMode madmin.HealScanMode) (dataUsageCache, error) {
+	atomic.AddInt32(&client.scanning, 1)
+	defer atomic.AddInt32(&client.scanning, -1)
+
 	defer close(updates)
 	pr, pw := io.Pipe()
 	go func() {
@@ -281,6 +287,8 @@ func (client *storageRESTClient) DiskInfo(_ context.Context, metrics bool) (info
 		// transport is already down.
 		return info, errDiskNotFound
 	}
+	// Do not cache results from atomic variables
+	scanning := atomic.LoadInt32(&client.scanning) == 1
 	client.diskInfoCache.Once.Do(func() {
 		client.diskInfoCache.TTL = time.Second
 		client.diskInfoCache.Update = func() (interface{}, error) {
@@ -306,8 +314,9 @@ func (client *storageRESTClient) DiskInfo(_ context.Context, metrics bool) (info
 	})
 	val, err := client.diskInfoCache.Get()
 	if val != nil {
-		return val.(DiskInfo), err
+		info = val.(DiskInfo)
 	}
+	info.Scanning = scanning
 	return info, err
 }
 
diff --git a/cmd/xl-storage.go b/cmd/xl-storage.go
index b9314dc52..6199a7cca 100644
--- a/cmd/xl-storage.go
+++ b/cmd/xl-storage.go
@@ -462,6 +462,7 @@ func (s *xlStorage) readMetadata(ctx context.Context, itemPath string) ([]byte,
 func (s *xlStorage) NSScanner(ctx context.Context, cache dataUsageCache, updates chan<- dataUsageEntry, scanMode madmin.HealScanMode) (dataUsageCache, error) {
 	atomic.AddInt32(&s.scanning, 1)
 	defer atomic.AddInt32(&s.scanning, -1)
+
 	var err error
 	stopFn := globalScannerMetrics.log(scannerMetricScanBucketDrive, s.drivePath, cache.Info.Name)
 	defer func() {
@@ -650,6 +651,9 @@ func (s *xlStorage) NSScanner(ctx context.Context, cache dataUsageCache, updates
 // DiskInfo provides current information about disk space usage,
 // total free inodes and underlying filesystem.
 func (s *xlStorage) DiskInfo(_ context.Context, _ bool) (info DiskInfo, err error) {
+	// Do not cache results from atomic variables
+	scanning := atomic.LoadInt32(&s.scanning) == 1
+
 	s.diskInfoCache.Once.Do(func() {
 		s.diskInfoCache.TTL = time.Second
 		s.diskInfoCache.Update = func() (interface{}, error) {
@@ -677,7 +681,6 @@ func (s *xlStorage) DiskInfo(_ context.Context, _ bool) (info DiskInfo, err erro
 			// - if we found an unformatted disk (no 'format.json')
 			// - if we found healing tracker 'healing.bin'
 			dcinfo.Healing = errors.Is(err, errUnformattedDisk) || (s.Healing() != nil)
-			dcinfo.Scanning = atomic.LoadInt32(&s.scanning) == 1
 			dcinfo.ID = diskID
 			return dcinfo, err
 		}
@@ -687,6 +690,7 @@ func (s *xlStorage) DiskInfo(_ context.Context, _ bool) (info DiskInfo, err erro
 	if v != nil {
 		info = v.(DiskInfo)
 	}
+	info.Scanning = scanning
 	return info, err
 }