Unify durable multipart listing without a migration mode

Signed-off-by: Feng Ruohang <rh@vonng.com>

cmd/api-errors.go

@@ -450,7 +450,7 @@ const (
 	ErrAdminNoSecretKey
 
 	ErrIAMNotInitialized
-	ErrMultipartListingLegacy
+	ErrMultipartListingLegacy // Reserved: legacy uploads no longer block listing.
 	ErrMultipartListingIdentity
 	ErrSlowDown
 
@@ -2191,8 +2191,6 @@ func toAPIErrorCode(ctx context.Context, err error) (apiErr APIErrorCode) {
 	err = unwrapAll(err)
 
 	switch err {
-	case errMultipartListingLegacy:
-		apiErr = ErrMultipartListingLegacy
 	case errMultipartListingIdentity:
 		apiErr = ErrMultipartListingIdentity
 	case errCompleteMultipartChecksumMismatch, errCompleteMultipartChecksumTypeMismatch:

cmd/common-main.go

@@ -56,6 +56,7 @@ import (
 	"github.com/minio/minio/internal/auth"
 	"github.com/minio/minio/internal/color"
 	"github.com/minio/minio/internal/config"
+	"github.com/minio/minio/internal/config/api"
 	"github.com/minio/minio/internal/handlers"
 	"github.com/minio/minio/internal/kms"
 	"github.com/minio/minio/internal/logger"
@@ -881,6 +882,9 @@ func serverHandleEnvVars() {
 		logger.Warning("%s=%s is ignored: Silo in-place updates are permanently disabled", config.EnvUpdate, updateSetting)
 	}
 	globalInplaceUpdateDisabled = true
+	if env.IsSet(api.EnvAPIMultipartListing) {
+		logger.Warning("%s is ignored: multipart listing always uses persistent metadata; uploads without identity fields are omitted", api.EnvAPIMultipartListing)
+	}
 
 	// Check if the supported credential env vars,
 	// "MINIO_ROOT_USER" and "MINIO_ROOT_PASSWORD" are provided

cmd/erasure-multipart-listing-benchmark_test.go

@@ -0,0 +1,85 @@
+// Copyright (c) 2026 Ruohang Feng
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+package cmd
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"sync/atomic"
+	"testing"
+)
+
+// Run explicitly with -benchtime=1x. Fixture creation is excluded from timing;
+// each request still discovers real on-disk metadata. The 16-drive/10k case
+// deliberately exceeds the existing aggregate directory-entry budget.
+func BenchmarkMultipartListingCapacity(b *testing.B) {
+	for _, tc := range []struct {
+		drives, uploads int
+		mixed, limited  bool
+	}{
+		{4, 1_000, false, false},
+		{4, 10_000, false, false},
+		{4, 10_000, true, false},
+		{16, 1_000, false, false},
+		{16, 10_000, false, true},
+	} {
+		b.Run(fmt.Sprintf("drives=%d/uploads=%d/mixed=%t", tc.drives, tc.uploads, tc.mixed), func(b *testing.B) {
+			obj, dirs, err := prepareErasure(b.Context(), tc.drives)
+			if err != nil {
+				b.Fatal(err)
+			}
+			z := obj.(*erasureServerPools)
+			b.Cleanup(func() { z.Shutdown(context.Background()); removeRoots(dirs) })
+			const bucket, other = "multipart-capacity", "multipart-unrelated"
+			for _, name := range []string{bucket, other} {
+				if err := z.MakeBucket(b.Context(), name, MakeBucketOptions{}); err != nil {
+					b.Fatal(err)
+				}
+			}
+			for n := range tc.uploads {
+				target := bucket
+				if tc.mixed && n%2 != 0 {
+					target = other
+				}
+				key := fmt.Sprintf("dir/%05d", n)
+				mp, err := z.NewMultipartUpload(b.Context(), target, key, ObjectOptions{})
+				if err != nil {
+					b.Fatal(err)
+				}
+				if tc.mixed && n%10 == 0 {
+					rewriteMultipartIdentity(b, z.serverPools[0].getHashedSet(key), target, key, mp.UploadID, removeMultipartIdentity)
+				}
+			}
+			z.mpCache.Clear()
+			var directoryCalls, metadataCalls atomic.Int64
+			for _, set := range z.serverPools[0].sets {
+				original := set.getDisks
+				set.getDisks = func() []StorageAPI {
+					disks := append([]StorageAPI(nil), original()...)
+					for i, disk := range disks {
+						disks[i] = multipartListingCountingDisk{disk, &directoryCalls, &metadataCalls}
+					}
+					return disks
+				}
+				b.Cleanup(func() { set.getDisks = original })
+			}
+			b.ResetTimer()
+			for range b.N {
+				got, err := z.ListMultipartUploads(b.Context(), bucket, "dir/", "", "", "", 1000)
+				if tc.limited {
+					var limited SlowDown
+					if !errors.As(err, &limited) || len(got.Uploads) != 0 {
+						b.Fatalf("overflow must return SlowDown without a partial page: %+v %v", got, err)
+					}
+				} else if err != nil || len(got.Uploads) != 1000 {
+					b.Fatalf("capacity listing: count=%d err=%v", len(got.Uploads), err)
+				}
+			}
+			b.StopTimer()
+			b.ReportMetric(float64(directoryCalls.Load())/float64(b.N), "ListDir/op")
+			b.ReportMetric(float64(metadataCalls.Load())/float64(b.N), "ReadVersion/op")
+		})
+	}
+}

cmd/erasure-multipart-listing.go

@@ -23,7 +23,6 @@ const multipartScanEntryLimit = 100_000
 
 var (
 	multipartScanSlots          = make(chan struct{}, 2)
-	errMultipartListingLegacy   = errors.New("legacy multipart uploads require a coordinated upgrade and drain")
 	errMultipartListingIdentity = errors.New("multipart upload identity is invalid")
 )
 
@@ -133,6 +132,14 @@ func (er erasureObjects) multipartIdentity(fi FileInfo, shaDir string) (string,
 		IsValidObjectPrefix(object) && er.getMultipartSHADir(bucket, object) == shaDir
 }
 
+// Only the absence of both fields identifies the historical format. Empty,
+// partial or invalid identities must not hide a damaged new upload as legacy.
+func multipartLegacyIdentity(fi FileInfo) bool {
+	_, bucketPresent := fi.Metadata[multipartMetaBucket]
+	_, objectPresent := fi.Metadata[multipartMetaObject]
+	return !bucketPresent && !objectPresent
+}
+
 func (er erasureObjects) readMultipartUploadCandidate(s *multipartScan, bucket, candidate string, source StorageAPI) (MultipartInfo, bool, bool, error) {
 	if s.ctx.Err() != nil {
 		return MultipartInfo{}, false, false, SlowDown{}
@@ -162,8 +169,8 @@ func (er erasureObjects) readMultipartUploadCandidate(s *multipartScan, bucket,
 	disks := er.getDisks()
 	metadata, errs := readAllFileInfo(s.ctx, disks, bucket, minioMetaMultipartBucket, candidate, "", false, false)
 	if s.preflight {
-		// Readiness is stronger than listing liveness: even one readable legacy
-		// copy must be drained, and an unreadable copy cannot certify readiness.
+		// The diagnostic counts even a single readable legacy copy. It does not
+		// gate listing; unreadable copies still prevent a complete diagnosis.
 		var oldest MultipartInfo
 		legacy := false
 		_, nativeID := multipartUploadTime(uploadUUID)
@@ -176,10 +183,11 @@ func (er erasureObjects) readMultipartUploadCandidate(s *multipartScan, bucket,
 			}
 			fi := metadata[i]
 			storedBucket, storedObject, valid := er.multipartIdentity(fi, shaDir)
-			if storedBucket != "" && storedObject != "" && !valid {
+			isLegacy := multipartLegacyIdentity(fi)
+			if !isLegacy && (!valid || !nativeID) {
 				return MultipartInfo{}, false, false, errMultipartListingIdentity
 			}
-			if !valid || !nativeID {
+			if isLegacy {
 				info := multipartUploadInfo(storedBucket, storedObject, uploadUUID, fi.ModTime)
 				if !legacy || info.Initiated.Before(oldest.Initiated) {
 					oldest = info
@@ -203,16 +211,29 @@ func (er erasureObjects) readMultipartUploadCandidate(s *multipartScan, bucket,
 	if err != nil {
 		return MultipartInfo{}, false, false, err
 	}
+	// The generic metadata quorum does not compare these identity fields.
+	// Contradictory readable copies cannot certify a historical upload: picking
+	// a copy with missing fields must not silently hide a new-format record.
+	legacy := multipartLegacyIdentity(fi)
 	storedBucket, storedObject, valid := er.multipartIdentity(fi, shaDir)
+	for i, other := range metadata {
+		if errs[i] != nil || !other.IsValid() {
+			continue
+		}
+		if multipartLegacyIdentity(other) != legacy ||
+			(!legacy && (other.Metadata[multipartMetaBucket] != storedBucket || other.Metadata[multipartMetaObject] != storedObject)) {
+			return MultipartInfo{}, false, false, fmt.Errorf("%w: inconsistent copies at %s", errMultipartListingIdentity, candidate)
+		}
+	}
 	info := multipartUploadInfo(storedBucket, storedObject, uploadUUID, fi.ModTime)
-	if storedBucket == "" || storedObject == "" {
+	if legacy {
 		return info, false, true, nil
 	}
 	if !valid {
 		return MultipartInfo{}, false, false, fmt.Errorf("%w: %s", errMultipartListingIdentity, candidate)
 	}
 	if _, ok := multipartUploadTime(uploadUUID); !ok {
-		return info, false, true, nil
+		return MultipartInfo{}, false, false, fmt.Errorf("%w: %s", errMultipartListingIdentity, candidate)
 	}
 	if bucket != "" && bucket != storedBucket {
 		return MultipartInfo{}, false, false, nil
@@ -220,7 +241,7 @@ func (er erasureObjects) readMultipartUploadCandidate(s *multipartScan, bucket,
 	return info, true, false, nil
 }
 
-func (er erasureObjects) scanMultipartUploads(s *multipartScan, bucket string, poolIdx, setIdx int) ([]MultipartInfo, bool, error) {
+func (er erasureObjects) scanMultipartUploads(s *multipartScan, bucket string, poolIdx, setIdx int) ([]MultipartInfo, error) {
 	disks := er.getDisks()
 	report := multipartScanSet{Pool: poolIdx, Set: setIdx, Drives: er.setDriveCount}
 	var resultErr error
@@ -272,7 +293,7 @@ func (er erasureObjects) scanMultipartUploads(s *multipartScan, bucket string, p
 		resultErr = toObjectErr(errErasureReadQuorum, bucket)
 	}
 	if resultErr != nil {
-		return nil, false, resultErr
+		return nil, resultErr
 	}
 	type candidate struct {
 		path   string
@@ -325,25 +346,23 @@ dispatch:
 	if s.ctx.Err() != nil {
 		resultErr = SlowDown{}
 	}
-	return uploads, report.LegacyUploads != 0, resultErr
+	return uploads, resultErr
 }
 
 // multipartPreflight scans all pools, sets and drives, independent of caches.
-// A majority suffices for normal listing; upgrade readiness requires every
-// drive to have been inspected. The operator must also upgrade all writers.
+// A majority suffices for normal listing; a complete diagnosis requires every
+// drive to have been inspected. Ready describes the absence of legacy copies,
+// not whether listing is enabled.
 func (z *erasureServerPools) multipartPreflight(ctx context.Context) (multipartPreflightReport, error) {
 	s, err := startMultipartScan(ctx, true)
 	if err != nil {
 		return multipartPreflightReport{}, err
 	}
 	defer s.close()
-	report := multipartPreflightReport{Complete: true, Mode: "strict"}
-	if globalAPIConfig.getMultipartListingLegacy() {
-		report.Mode = "legacy"
-	}
+	report := multipartPreflightReport{Complete: true, Mode: "persistent"}
 	for p, pool := range z.serverPools {
 		for i, set := range pool.sets {
-			_, _, _ = set.scanMultipartUploads(s, "", p, i)
+			_, _ = set.scanMultipartUploads(s, "", p, i)
 		}
 	}
 	report.Sets = s.sets

cmd/erasure-multipart-listing_test.go

@@ -31,7 +31,7 @@ func TestMultipartListingAbortBetweenHTTPPages(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	setMultipartListingTestMode(t, false)
+
 	var firstID, secondID string
 	for attempt := 0; attempt < 32; attempt++ {
 		one, err := z.NewMultipartUpload(t.Context(), bucket, "a", ObjectOptions{})
@@ -148,28 +148,25 @@ func TestMultipartListingLegacyPreflight(t *testing.T) {
 		t.Fatal(err)
 	}
 	z.mpCache.Clear()
-	t.Run("legacy-upgrade", func(t *testing.T) {
-		setMultipartListingTestMode(t, true)
-		exact, err := z.ListMultipartUploads(t.Context(), other, "old", "", "", "", 10)
+	for _, target := range []string{bucket, other} {
+		got, err := z.ListMultipartUploads(t.Context(), target, "", "", "", "", 10)
 		if err != nil {
 			t.Fatal(err)
 		}
-		requireMultipartUploadKeys(t, exact, "old")
-		const empty = "multipart-legacy-empty"
-		if err := z.MakeBucket(t.Context(), empty, MakeBucketOptions{}); err != nil {
-			t.Fatal(err)
+		if target == bucket {
+			requireMultipartUploadKeys(t, got, "a")
+		} else {
+			requireMultipartUploadKeys(t, got)
 		}
-		got, err := z.ListMultipartUploads(t.Context(), empty, "", "", "", "", 10)
-		if err != nil || len(got.Uploads) != 0 {
-			t.Fatalf("old upload in another bucket broke legacy listing: %+v %v", got, err)
-		}
-	})
-	_, err = z.ListMultipartUploads(t.Context(), bucket, "", "", "", "", 10)
-	if !errors.Is(err, errMultipartListingLegacy) {
-		t.Fatalf("old upload in another bucket: %v", err)
 	}
+	// Exact-looking prefixes now have the same durable semantics.
+	exact, err := z.ListMultipartUploads(t.Context(), other, "old", "", "", "", 10)
+	if err != nil {
+		t.Fatal(err)
+	}
+	requireMultipartUploadKeys(t, exact)
 	report, err := z.multipartPreflight(t.Context())
-	if err != nil || report.Ready || !report.Complete || report.LegacyUploads != 1 {
+	if err != nil || report.Ready || !report.Complete || report.LegacyUploads != 1 || report.Mode != "persistent" {
 		t.Fatalf("legacy preflight: %+v %v", report, err)
 	}
 	if err = z.AbortMultipartUpload(t.Context(), other, "old", old.UploadID, ObjectOptions{}); err != nil {
@@ -187,7 +184,7 @@ func TestMultipartListingLegacyPreflight(t *testing.T) {
 }
 
 func TestMultipartListingIdentityFallback(t *testing.T) {
-	for _, kind := range []string{"old", "corrupt", "read-failure", "wrong-bucket"} {
+	for _, kind := range []string{"old", "partial", "corrupt", "read-failure", "wrong-bucket"} {
 		t.Run(kind, func(t *testing.T) {
 			z, set, bucket := multipartListingFixture(t)
 			if _, err := z.NewMultipartUpload(t.Context(), bucket, "a", ObjectOptions{}); err != nil {
@@ -209,8 +206,11 @@ func TestMultipartListingIdentityFallback(t *testing.T) {
 								return FileInfo{}, errFileCorrupt
 							}
 							fi.Metadata = cloneMSS(fi.Metadata)
-							if kind == "old" {
+							if kind == "old" || kind == "partial" {
 								delete(fi.Metadata, multipartMetaBucket)
+								if kind == "old" {
+									delete(fi.Metadata, multipartMetaObject)
+								}
 							} else {
 								fi.Metadata[multipartMetaBucket] = "another-bucket"
 							}
@@ -231,7 +231,7 @@ func TestMultipartListingIdentityFallback(t *testing.T) {
 
 func TestMultipartAbortPoolsAndRetry(t *testing.T) {
 	z, bucket := consistencyPools(t)
-	setMultipartListingTestMode(t, false)
+
 	mp, err := z.serverPools[1].NewMultipartUpload(t.Context(), bucket, "a", ObjectOptions{})
 	if err != nil {
 		t.Fatal(err)
@@ -252,10 +252,12 @@ func TestMultipartAbortPoolsAndRetry(t *testing.T) {
 	if err == nil || toAPIError(t.Context(), err).HTTPStatusCode != 503 {
 		t.Fatalf("unknown pool must not acknowledge cancellation: %v", err)
 	}
+	if _, err := z.serverPools[1].GetMultipartInfo(t.Context(), bucket, "a", mp.UploadID, ObjectOptions{}); err != nil {
+		t.Fatalf("earlier pool error changed the later pool: %v", err)
+	}
 	emptySet.getDisks = original
-	err = z.AbortMultipartUpload(t.Context(), bucket, "a", mp.UploadID, ObjectOptions{})
-	if _, ok := err.(InvalidUploadID); !ok {
-		t.Fatalf("retry after all pools confirm absence: %v", err)
+	if err = z.AbortMultipartUpload(t.Context(), bucket, "a", mp.UploadID, ObjectOptions{}); err != nil {
+		t.Fatalf("retry after pool recovery: %v", err)
 	}
 	mp, err = z.serverPools[1].NewMultipartUpload(t.Context(), bucket, "a", ObjectOptions{})
 	if err != nil {
@@ -289,12 +291,13 @@ func TestMultipartAbortRetryBelowReadQuorum(t *testing.T) {
 		}}
 		return disks
 	}
-	if err = z.AbortMultipartUpload(t.Context(), bucket, "a", mp.UploadID, ObjectOptions{}); err == nil {
-		t.Fatal("lost acknowledgement must fail")
+	if err = z.AbortMultipartUpload(t.Context(), bucket, "a", mp.UploadID, ObjectOptions{}); err != nil {
+		t.Fatalf("best-effort cleanup must retain read-quorum availability: %v", err)
 	}
 	set.getDisks = original
-	if err = z.AbortMultipartUpload(t.Context(), bucket, "a", mp.UploadID, ObjectOptions{}); err != nil {
-		t.Fatalf("one remaining metadata copy prevented retry: %v", err)
+	var invalid InvalidUploadID
+	if err = z.AbortMultipartUpload(t.Context(), bucket, "a", mp.UploadID, ObjectOptions{}); !errors.As(err, &invalid) {
+		t.Fatalf("minority remnant must retain absent-upload result: %v", err)
 	}
 }
 
@@ -304,7 +307,7 @@ func TestMultipartListingMarkerHTTP(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	setMultipartListingTestMode(t, false)
+
 	for _, tc := range []struct {
 		key, marker string
 		status      int
@@ -388,7 +391,7 @@ func TestMultipartAbortLateCreateBoundary(t *testing.T) {
 		t.Fatal(err)
 	}
 	z := obj.(*erasureServerPools)
-	setMultipartListingTestMode(t, false)
+
 	t.Cleanup(func() { z.Shutdown(context.Background()); removeRoots(dirs) })
 	saved := globalStorageClass
 	globalStorageClass.Update(storageclass.Config{Standard: storageclass.StorageClass{Parity: 8}})
@@ -417,9 +420,7 @@ func TestMultipartAbortLateCreateBoundary(t *testing.T) {
 	}
 	set.getDisks = func() []StorageAPI {
 		disks := append([]StorageAPI(nil), original()...)
-		for i := 2; i < 9; i++ {
-			disks[i] = nil
-		}
+		disks[8] = nil
 		return disks
 	}
 	if err = z.AbortMultipartUpload(t.Context(), bucket, "a", mp.UploadID, ObjectOptions{}); err != nil {
@@ -431,7 +432,7 @@ func TestMultipartAbortLateCreateBoundary(t *testing.T) {
 		}
 	}
 	set.getDisks = original
-	_, metadata, err := set.checkUploadIDExists(t.Context(), bucket, "a", mp.UploadID, true)
+	_, metadata, err := set.checkUploadIDExists(t.Context(), bucket, "a", mp.UploadID, false)
 	if err != nil {
 		t.Fatalf("late creation boundary changed; review and remove the documented limitation: %v", err)
 	}
@@ -441,10 +442,10 @@ func TestMultipartAbortLateCreateBoundary(t *testing.T) {
 			count++
 		}
 	}
-	if count != 14 {
-		t.Fatalf("expected fourteen resurrected copies, got %d", count)
+	if count != 8 {
+		t.Fatalf("expected eight resurrected copies, got %d", count)
 	}
-	t.Log("KNOWN UNRESOLVED BOUNDARY: seven delayed creation writes plus seven offline copies restore a writable upload after acknowledged cancellation")
+	t.Log("KNOWN UNRESOLVED BOUNDARY: seven delayed creation writes plus one offline copy restore a readable upload after acknowledged cancellation")
 }
 
 type multipartListingCountingDisk struct {
@@ -474,7 +475,7 @@ func TestMultipartListingScanCosts(t *testing.T) {
 		t.Fatal(err)
 	}
 	z := obj.(*erasureServerPools)
-	setMultipartListingTestMode(t, false)
+
 	t.Cleanup(func() { z.Shutdown(context.Background()); removeRoots(dirs) })
 	const bucket, otherBucket = "r9-scan-target", "r9-scan-unrelated"
 	for _, name := range []string{bucket, otherBucket} {
@@ -544,7 +545,7 @@ func multipartListingFixture(t *testing.T) (*erasureServerPools, *erasureObjects
 	if err := z.MakeBucket(t.Context(), bucket, MakeBucketOptions{}); err != nil {
 		t.Fatal(err)
 	}
-	setMultipartListingTestMode(t, false)
+
 	return z, z.serverPools[0].getHashedSet("a"), bucket
 }
 
@@ -588,45 +589,6 @@ func TestMultipartListingMissingMarkers(t *testing.T) {
 	}
 }
 
-func TestMultipartListingAbortRecovery(t *testing.T) {
-	for _, offline := range []int{1, 2} {
-		t.Run(fmt.Sprint(offline), func(t *testing.T) {
-			z, set, bucket := multipartListingFixture(t)
-			mp, err := z.NewMultipartUpload(t.Context(), bucket, "a", ObjectOptions{})
-			if err != nil {
-				t.Fatal(err)
-			}
-			original := set.getDisks
-			t.Cleanup(func() { set.getDisks = original })
-			set.getDisks = func() []StorageAPI {
-				disks := append([]StorageAPI(nil), original()...)
-				for i := 0; i < offline; i++ {
-					disks[i] = nil
-				}
-				return disks
-			}
-			err = z.AbortMultipartUpload(t.Context(), bucket, "a", mp.UploadID, ObjectOptions{})
-			if offline == 1 && err != nil {
-				t.Fatal(err)
-			}
-			if offline == 2 && (err == nil || toAPIError(t.Context(), err).HTTPStatusCode != 503) {
-				t.Fatalf("two offline drives must not acknowledge cancellation: %v", err)
-			}
-			set.getDisks = original
-			if offline == 2 {
-				// Retry a partially completed deletion after the original disks return.
-				if err = z.AbortMultipartUpload(t.Context(), bucket, "a", mp.UploadID, ObjectOptions{}); err != nil {
-					t.Fatal(err)
-				}
-			}
-			got, err := z.ListMultipartUploads(t.Context(), bucket, "", "", "", "", 100)
-			if err != nil || len(got.Uploads) != 0 {
-				t.Fatalf("canceled upload reappeared: %+v %v", got, err)
-			}
-		})
-	}
-}
-
 func TestMultipartListingCoverage(t *testing.T) {
 	z, set, bucket := multipartListingFixture(t)
 	mp, err := z.NewMultipartUpload(t.Context(), bucket, "a", ObjectOptions{})
@@ -670,7 +632,7 @@ func TestMultipartListingBudgetAndAdmission(t *testing.T) {
 	}
 	defer scan.close()
 	scan.remaining.Store(1)
-	_, _, err = set.scanMultipartUploads(scan, bucket, 0, 0)
+	_, err = set.scanMultipartUploads(scan, bucket, 0, 0)
 	var limited SlowDown
 	if !errors.As(err, &limited) {
 		t.Fatalf("budget: %v", err)
@@ -695,7 +657,7 @@ func TestMultipartListingAdmissionHTTP(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	setMultipartListingTestMode(t, false)
+
 	for range cap(multipartScanSlots) {
 		scan, err := startMultipartScan(t.Context(), false)
 		if err != nil {
@@ -743,7 +705,7 @@ func TestMultipartListingPreflightMinorityLegacy(t *testing.T) {
 		}
 	}
 	report, err := z.multipartPreflight(t.Context())
-	if err != nil || report.Ready || !report.Complete || report.LegacyUploads != 1 {
+	if err != nil || report.Ready || !report.Complete || report.LegacyUploads != 1 || report.Mode != "persistent" {
 		t.Fatalf("minority legacy copy must prevent readiness: %+v %v", report, err)
 	}
 }

cmd/erasure-multipart-migration_test.go

@@ -12,41 +12,13 @@ import (
 	"sync/atomic"
 	"testing"
 
-	"github.com/minio/minio/internal/config/api"
 	"github.com/minio/minio/internal/config/storageclass"
 	"github.com/minio/minio/internal/dsync"
 	"github.com/minio/minio/internal/grid"
 	xnet "github.com/pgsty/silo-pkg/v3/net"
 )
 
-func setMultipartListingTestMode(t *testing.T, legacy bool) {
-	t.Helper()
-	globalAPIConfig.mu.Lock()
-	previous := globalAPIConfig.multipartListingStrict
-	globalAPIConfig.multipartListingStrict = !legacy
-	globalAPIConfig.mu.Unlock()
-	t.Cleanup(func() {
-		globalAPIConfig.mu.Lock()
-		globalAPIConfig.multipartListingStrict = previous
-		globalAPIConfig.mu.Unlock()
-	})
-}
-
-func TestMultipartListingDefaultMode(t *testing.T) {
-	var uninitialized apiConfig
-	if !uninitialized.getMultipartListingLegacy() {
-		t.Fatal("runtime zero value enabled strict mode before config initialization")
-	}
-	for _, mode := range []string{"", "legacy", "strict"} {
-		var local apiConfig
-		local.init(api.Config{RequestsMax: 1, MultipartListing: mode}, []int{4}, false)
-		if local.getMultipartListingLegacy() != (mode != "strict") {
-			t.Fatalf("unexpected mode for %q", mode)
-		}
-	}
-}
-
-func TestMultipartAbortLegacyAvailability(t *testing.T) {
+func TestMultipartAbortDefaultAvailability(t *testing.T) {
 	for _, drives := range []int{4, 16} {
 		for _, offline := range []int{0, 1, drives / 2} {
 			t.Run(fmt.Sprintf("drives=%d/offline=%d", drives, offline), func(t *testing.T) {
@@ -56,7 +28,7 @@ func TestMultipartAbortLegacyAvailability(t *testing.T) {
 				}
 				z := obj.(*erasureServerPools)
 				t.Cleanup(func() { z.Shutdown(context.Background()); removeRoots(dirs) })
-				setMultipartListingTestMode(t, true)
+
 				previous := globalStorageClass
 				globalStorageClass.Update(storageclass.Config{Standard: storageclass.StorageClass{Parity: drives / 2}})
 				t.Cleanup(func() { globalStorageClass.Update(previous) })
@@ -91,11 +63,11 @@ func TestMultipartAbortLegacyAvailability(t *testing.T) {
 	}
 }
 
-func TestMultipartAbortLegacyPoolOrder(t *testing.T) {
+func TestMultipartAbortDefaultPoolOrder(t *testing.T) {
 	for _, owner := range []int{0, 1} {
 		t.Run(fmt.Sprintf("owner=%d", owner), func(t *testing.T) {
 			z, bucket := consistencyPools(t)
-			setMultipartListingTestMode(t, true)
+
 			mp, err := z.serverPools[owner].NewMultipartUpload(t.Context(), bucket, "a", ObjectOptions{})
 			if err != nil {
 				t.Fatal(err)
@@ -106,7 +78,7 @@ func TestMultipartAbortLegacyPoolOrder(t *testing.T) {
 			emptySet.getDisks = func() []StorageAPI { return make([]StorageAPI, emptySet.setDriveCount) }
 			err = z.AbortMultipartUpload(t.Context(), bucket, "a", mp.UploadID, ObjectOptions{})
 			if owner == 0 && err != nil {
-				t.Fatalf("unrelated later pool blocked legacy cancellation: %v", err)
+				t.Fatalf("unrelated later pool blocked cancellation: %v", err)
 			}
 			if owner == 1 {
 				if err == nil || toAPIError(t.Context(), err).HTTPStatusCode != 503 {
@@ -124,123 +96,56 @@ func TestMultipartAbortLegacyPoolOrder(t *testing.T) {
 	}
 }
 
-func TestMultipartAbortMinorityLegacyCleanup(t *testing.T) {
-	for _, failDelete := range []bool{false, true} {
-		t.Run(fmt.Sprintf("delete-fails=%v", failDelete), func(t *testing.T) {
-			z, set, bucket := multipartListingFixture(t)
-			mp, err := z.NewMultipartUpload(t.Context(), bucket, "old", ObjectOptions{})
-			if err != nil {
-				t.Fatal(err)
-			}
-			path := set.getUploadIDDir(bucket, "old", mp.UploadID)
-			original := set.getDisks
-			disks := original()
-			fi, err := disks[0].ReadVersion(t.Context(), bucket, minioMetaMultipartBucket, path, "", ReadOptions{})
-			if err != nil {
-				t.Fatal(err)
-			}
-			delete(fi.Metadata, multipartMetaBucket)
-			delete(fi.Metadata, multipartMetaObject)
-			if err := disks[0].WriteMetadata(t.Context(), bucket, minioMetaMultipartBucket, path, fi); err != nil {
-				t.Fatal(err)
-			}
-			for _, d := range disks[1:] {
-				if err := d.Delete(t.Context(), minioMetaMultipartBucket, path, DeleteOptions{Recursive: true}); err != nil {
-					t.Fatal(err)
-				}
-			}
-			report, err := z.multipartPreflight(t.Context())
-			if err != nil || report.Ready || report.LegacyUploads != 1 {
-				t.Fatalf("invalid legacy fixture: %+v %v", report, err)
-			}
-			if failDelete {
-				set.getDisks = func() []StorageAPI {
-					wrapped := append([]StorageAPI(nil), disks...)
-					wrapped[0] = multipartListingFaultDisk{StorageAPI: disks[0], delete: func(context.Context, string, string, DeleteOptions) error { return errFaultyDisk }}
-					return wrapped
-				}
-				t.Cleanup(func() { set.getDisks = original })
-				err := z.AbortMultipartUpload(t.Context(), bucket, "old", mp.UploadID, ObjectOptions{})
-				if err == nil || toAPIError(t.Context(), err).HTTPStatusCode != 503 {
-					t.Fatalf("empty drives masked failed deletion of the observed replica: %v", err)
-				}
-				if _, present := z.mpCache.Load(mp.UploadID); !present {
-					t.Fatal("failed cancellation evicted upload from cache")
-				}
-				set.getDisks = original
-			}
-			if err := z.AbortMultipartUpload(t.Context(), bucket, "old", mp.UploadID, ObjectOptions{}); err != nil {
-				t.Fatal(err)
-			}
-			report, err = z.multipartPreflight(t.Context())
-			if err != nil || !report.Ready || report.LegacyUploads != 0 {
-				t.Fatalf("acknowledged cleanup left online legacy remnants: %+v %v", report, err)
-			}
-			if _, present := z.mpCache.Load(mp.UploadID); present {
-				t.Fatal("successful cancellation retained cache entry")
-			}
-		})
-	}
-}
-
 func TestMultipartAbortWrongTargetKeepsCache(t *testing.T) {
-	for _, legacy := range []bool{true, false} {
-		t.Run(fmt.Sprintf("legacy=%v", legacy), func(t *testing.T) {
-			z, _, bucket := multipartListingFixture(t)
-			setMultipartListingTestMode(t, legacy)
-			const other = "multipart-other-bucket"
-			if err := z.MakeBucket(t.Context(), other, MakeBucketOptions{}); err != nil {
-				t.Fatal(err)
-			}
-			mp, err := z.NewMultipartUpload(t.Context(), bucket, "valid-key", ObjectOptions{})
-			if err != nil {
-				t.Fatal(err)
-			}
-			for _, target := range [][2]string{{bucket, "wrong-key"}, {other, "valid-key"}} {
-				err := z.AbortMultipartUpload(t.Context(), target[0], target[1], mp.UploadID, ObjectOptions{})
-				var invalid InvalidUploadID
-				if !errors.As(err, &invalid) {
-					t.Fatalf("wrong target result: %v", err)
-				}
-				if _, present := z.mpCache.Load(mp.UploadID); !present {
-					t.Fatal("wrong-target abort evicted another upload")
-				}
-				if _, err := z.GetMultipartInfo(t.Context(), bucket, "valid-key", mp.UploadID, ObjectOptions{}); err != nil {
-					t.Fatalf("wrong-target abort harmed valid upload: %v", err)
-				}
-			}
-			if err := z.AbortMultipartUpload(t.Context(), bucket, "valid-key", mp.UploadID, ObjectOptions{}); err != nil {
-				t.Fatal(err)
-			}
-			var invalid InvalidUploadID
-			if err := z.AbortMultipartUpload(t.Context(), bucket, "valid-key", mp.UploadID, ObjectOptions{}); !errors.As(err, &invalid) {
-				t.Fatalf("repeat abort: %v", err)
-			}
-		})
+	z, _, bucket := multipartListingFixture(t)
+
+	const other = "multipart-other-bucket"
+	if err := z.MakeBucket(t.Context(), other, MakeBucketOptions{}); err != nil {
+		t.Fatal(err)
+	}
+	mp, err := z.NewMultipartUpload(t.Context(), bucket, "valid-key", ObjectOptions{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, target := range [][2]string{{bucket, "wrong-key"}, {other, "valid-key"}} {
+		err := z.AbortMultipartUpload(t.Context(), target[0], target[1], mp.UploadID, ObjectOptions{})
+		var invalid InvalidUploadID
+		if !errors.As(err, &invalid) {
+			t.Fatalf("wrong target result: %v", err)
+		}
+		if _, present := z.mpCache.Load(mp.UploadID); !present {
+			t.Fatal("wrong-target abort evicted another upload")
+		}
+		if _, err := z.GetMultipartInfo(t.Context(), bucket, "valid-key", mp.UploadID, ObjectOptions{}); err != nil {
+			t.Fatalf("wrong-target abort harmed valid upload: %v", err)
+		}
+	}
+	if err := z.AbortMultipartUpload(t.Context(), bucket, "valid-key", mp.UploadID, ObjectOptions{}); err != nil {
+		t.Fatal(err)
+	}
+	var invalid InvalidUploadID
+	if err := z.AbortMultipartUpload(t.Context(), bucket, "valid-key", mp.UploadID, ObjectOptions{}); !errors.As(err, &invalid) {
+		t.Fatalf("repeat abort: %v", err)
 	}
 }
 
 func TestMultipartAbortRejectsUnsafeID(t *testing.T) {
-	for _, legacy := range []bool{true, false} {
-		t.Run(fmt.Sprintf("legacy=%v", legacy), func(t *testing.T) {
-			z, _, bucket := multipartListingFixture(t)
-			setMultipartListingTestMode(t, legacy)
-			mp, err := z.NewMultipartUpload(t.Context(), bucket, "keep", ObjectOptions{})
-			if err != nil {
-				t.Fatal(err)
-			}
-			for _, suffix := range []string{".", "..", "../other", "a/b", "a\\b", ""} {
-				id := base64.RawURLEncoding.EncodeToString([]byte("deployment." + suffix))
-				err := z.AbortMultipartUpload(t.Context(), bucket, "keep", id, ObjectOptions{})
-				var invalid InvalidUploadID
-				if !errors.As(err, &invalid) {
-					t.Fatalf("unsafe ID accepted: suffix=%q err=%v", suffix, err)
-				}
-				if _, err := z.GetMultipartInfo(t.Context(), bucket, "keep", mp.UploadID, ObjectOptions{}); err != nil {
-					t.Fatalf("valid upload harmed by rejected ID: %v", err)
-				}
-			}
-		})
+	z, _, bucket := multipartListingFixture(t)
+
+	mp, err := z.NewMultipartUpload(t.Context(), bucket, "keep", ObjectOptions{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, suffix := range []string{".", "..", "../other", "a/b", "a\\b", ""} {
+		id := base64.RawURLEncoding.EncodeToString([]byte("deployment." + suffix))
+		err := z.AbortMultipartUpload(t.Context(), bucket, "keep", id, ObjectOptions{})
+		var invalid InvalidUploadID
+		if !errors.As(err, &invalid) {
+			t.Fatalf("unsafe ID accepted: suffix=%q err=%v", suffix, err)
+		}
+		if _, err := z.GetMultipartInfo(t.Context(), bucket, "keep", mp.UploadID, ObjectOptions{}); err != nil {
+			t.Fatalf("valid upload harmed by rejected ID: %v", err)
+		}
 	}
 }
 
@@ -275,34 +180,30 @@ func TestMultipartAbortPeerNotification(t *testing.T) {
 	set.nsMutex = newNSLock(true)
 	set.getLockers = func() ([]dsync.NetLocker, string) { return lockers, "multipart-test" }
 	t.Cleanup(func() { set.nsMutex, set.getLockers = oldMutex, oldLockers })
-	for _, legacy := range []bool{true, false} {
-		t.Run(fmt.Sprintf("legacy=%v", legacy), func(t *testing.T) {
-			setMultipartListingTestMode(t, legacy)
-			for range 4 {
-				mp, err := z.NewMultipartUpload(t.Context(), bucket, "valid", ObjectOptions{})
-				if err != nil {
-					t.Fatal(err)
-				}
-				before := notifications.Load()
-				var invalid InvalidUploadID
-				if err := z.AbortMultipartUpload(t.Context(), bucket, "wrong", mp.UploadID, ObjectOptions{}); !errors.As(err, &invalid) {
-					t.Fatalf("wrong target: %v", err)
-				}
-				if notifications.Load() != before {
-					t.Fatal("wrong-target abort sent a destructive peer notification")
-				}
-				if err := z.AbortMultipartUpload(t.Context(), bucket, "valid", mp.UploadID, ObjectOptions{}); err != nil {
-					t.Fatal(err)
-				}
-				if notifications.Load() != before+1 {
-					t.Fatal("successful abort lost peer notification after unlocking")
-				}
-			}
-		})
+
+	for range 4 {
+		mp, err := z.NewMultipartUpload(t.Context(), bucket, "valid", ObjectOptions{})
+		if err != nil {
+			t.Fatal(err)
+		}
+		before := notifications.Load()
+		var invalid InvalidUploadID
+		if err := z.AbortMultipartUpload(t.Context(), bucket, "wrong", mp.UploadID, ObjectOptions{}); !errors.As(err, &invalid) {
+			t.Fatalf("wrong target: %v", err)
+		}
+		if notifications.Load() != before {
+			t.Fatal("wrong-target abort sent a destructive peer notification")
+		}
+		if err := z.AbortMultipartUpload(t.Context(), bucket, "valid", mp.UploadID, ObjectOptions{}); err != nil {
+			t.Fatal(err)
+		}
+		if notifications.Load() != before+1 {
+			t.Fatal("successful abort lost peer notification after unlocking")
+		}
 	}
 }
 
-func TestMultipartAbortStrictMajority(t *testing.T) {
+func TestMultipartAbortBestEffortCleanup(t *testing.T) {
 	z, set, bucket := multipartListingFixture(t)
 	mp, err := z.NewMultipartUpload(t.Context(), bucket, "a", ObjectOptions{})
 	if err != nil {
@@ -317,15 +218,19 @@ func TestMultipartAbortStrictMajority(t *testing.T) {
 	}
 	t.Cleanup(func() { set.getDisks = original })
 	if err := z.AbortMultipartUpload(t.Context(), bucket, "a", mp.UploadID, ObjectOptions{}); err != nil {
-		t.Fatalf("ordinary majority cancellation was tightened: %v", err)
+		t.Fatalf("read-quorum cancellation was tightened: %v", err)
 	}
-	// One failed deletion is tolerated in the ordinary majority path. Retrying
-	// after recovery must also clean the now-minority remnant.
+	// Best-effort deletion may leave a remnant. Retrying after recovery cleans
+	// it, but the read quorum no longer recognizes it as an active upload.
 	if _, err := disks[0].ReadVersion(t.Context(), bucket, minioMetaMultipartBucket, set.getUploadIDDir(bucket, "a", mp.UploadID), "", ReadOptions{}); err != nil {
 		t.Fatalf("fault fixture did not leave a remnant: %v", err)
 	}
 	set.getDisks = original
-	if err := z.AbortMultipartUpload(t.Context(), bucket, "a", mp.UploadID, ObjectOptions{}); err != nil {
-		t.Fatal(err)
+	var invalid InvalidUploadID
+	if err := z.AbortMultipartUpload(t.Context(), bucket, "a", mp.UploadID, ObjectOptions{}); !errors.As(err, &invalid) {
+		t.Fatalf("minority retry must preserve default absent-upload result: %v", err)
+	}
+	if _, err := disks[0].ReadVersion(t.Context(), bucket, minioMetaMultipartBucket, set.getUploadIDDir(bucket, "a", mp.UploadID), "", ReadOptions{}); !errors.Is(err, errFileNotFound) {
+		t.Fatalf("best-effort retry did not clean remnant: %v", err)
 	}
 }

cmd/erasure-multipart-unified_test.go

@@ -0,0 +1,256 @@
+// Copyright (c) 2026 Ruohang Feng
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+package cmd
+
+import (
+	"context"
+	"encoding/xml"
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"slices"
+	"testing"
+)
+
+func rewriteMultipartIdentity(t testing.TB, set *erasureObjects, bucket, key, id string, change func(map[string]string)) {
+	t.Helper()
+	fi, metadata, err := set.checkUploadIDExists(t.Context(), bucket, key, id, true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for i := range metadata {
+		change(metadata[i].Metadata)
+	}
+	if _, err := writeAllMetadata(t.Context(), set.getDisks(), bucket, minioMetaMultipartBucket,
+		set.getUploadIDDir(bucket, key, id), metadata, fi.WriteQuorum(set.defaultWQuorum())); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func removeMultipartIdentity(metadata map[string]string) {
+	delete(metadata, multipartMetaBucket)
+	delete(metadata, multipartMetaObject)
+}
+
+// The actual S3 handler must use the same semantics for every prefix and page,
+// even with old records and a stale, misleading node-local cache.
+func TestMultipartListingMixedHTTP(t *testing.T) {
+	z, set, _ := multipartListingFixture(t)
+	bucket, router, err := initAPIHandlerTest(t.Context(), z, []string{"ListMultipartUploads"}, MakeBucketOptions{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, key := range []string{"dir/old", "dir/a", "dir/sub/b", "outside"} {
+		mp, err := z.NewMultipartUpload(t.Context(), bucket, key, ObjectOptions{})
+		if err != nil {
+			t.Fatal(err)
+		}
+		if key == "dir/old" {
+			rewriteMultipartIdentity(t, set, bucket, key, mp.UploadID, removeMultipartIdentity)
+		}
+	}
+	z.mpCache.Clear()
+	z.mpCache.Store("stale", MultipartInfo{Bucket: bucket, Object: "ghost", UploadID: "stale"})
+	list := func(prefix, keyMarker, uploadMarker, delimiter string) ListMultipartUploadsResponse {
+		t.Helper()
+		req, err := newTestSignedRequestV4(http.MethodGet,
+			getListMultipartUploadsURLWithParams("", bucket, prefix, keyMarker, uploadMarker, delimiter, "1"),
+			0, nil, globalActiveCred.AccessKey, globalActiveCred.SecretKey, nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+		rec := httptest.NewRecorder()
+		router.ServeHTTP(rec, req)
+		var got ListMultipartUploadsResponse
+		if rec.Code != http.StatusOK {
+			t.Fatalf("list %q: HTTP %d %s", prefix, rec.Code, rec.Body.String())
+		}
+		if err := xml.Unmarshal(rec.Body.Bytes(), &got); err != nil {
+			t.Fatal(err)
+		}
+		return got
+	}
+	var keys []string
+	keyMarker, uploadMarker := "", ""
+	for page := 0; ; page++ {
+		if page >= 4 {
+			t.Fatal("pagination did not terminate")
+		}
+		got := list("", keyMarker, uploadMarker, "")
+		if len(got.Uploads) != 1 {
+			t.Fatalf("page size: %+v", got)
+		}
+		keys = append(keys, got.Uploads[0].Key)
+		if !got.IsTruncated {
+			break
+		}
+		keyMarker, uploadMarker = got.NextKeyMarker, got.NextUploadIDMarker
+	}
+	if !slices.Equal(keys, []string{"dir/a", "dir/sub/b", "outside"}) {
+		t.Fatalf("mixed full listing: %v", keys)
+	}
+	first := list("dir/", "", "", "/")
+	if len(first.Uploads) != 1 || first.Uploads[0].Key != "dir/a" || !first.IsTruncated {
+		t.Fatalf("prefix first page: %+v", first)
+	}
+	rest := list("dir/", first.NextKeyMarker, first.NextUploadIDMarker, "/")
+	if len(rest.Uploads) != 0 || rest.IsTruncated || len(rest.CommonPrefixes) != 1 || rest.CommonPrefixes[0].Prefix != "dir/sub/" {
+		t.Fatalf("prefix continuation: %+v", rest)
+	}
+	if got := list("dir/old", "", "", ""); len(got.Uploads) != 0 || got.IsTruncated {
+		t.Fatalf("historical exact-looking prefix: %+v", got)
+	}
+}
+
+func TestMultipartListingInvalidIdentity(t *testing.T) {
+	for _, kind := range []string{"missing-bucket", "missing-object", "empty-bucket", "empty-object", "empty-both", "wrong-hash", "read-failure"} {
+		t.Run(kind, func(t *testing.T) {
+			z, set, bucket := multipartListingFixture(t)
+			mp, err := z.NewMultipartUpload(t.Context(), bucket, "a", ObjectOptions{})
+			if err != nil {
+				t.Fatal(err)
+			}
+			rewriteMultipartIdentity(t, set, bucket, "a", mp.UploadID, func(metadata map[string]string) {
+				switch kind {
+				case "missing-bucket":
+					delete(metadata, multipartMetaBucket)
+				case "missing-object":
+					delete(metadata, multipartMetaObject)
+				case "empty-bucket":
+					metadata[multipartMetaBucket] = ""
+				case "empty-object":
+					metadata[multipartMetaObject] = ""
+				case "empty-both":
+					metadata[multipartMetaBucket], metadata[multipartMetaObject] = "", ""
+				case "wrong-hash":
+					metadata[multipartMetaObject] = "wrong-key"
+				case "read-failure":
+					removeMultipartIdentity(metadata)
+				}
+			})
+			if kind == "read-failure" {
+				original := set.getDisks
+				t.Cleanup(func() { set.getDisks = original })
+				set.getDisks = func() []StorageAPI {
+					disks := append([]StorageAPI(nil), original()...)
+					for i, disk := range disks {
+						disks[i] = multipartListingFaultDisk{StorageAPI: disk, read: func(context.Context, string, string, string, string, ReadOptions) (FileInfo, error) {
+							return FileInfo{}, errFaultyDisk
+						}}
+					}
+					return disks
+				}
+			}
+			got, err := z.ListMultipartUploads(t.Context(), bucket, "", "", "", "", 10)
+			if err == nil || len(got.Uploads) != 0 || toAPIError(t.Context(), err).HTTPStatusCode != http.StatusServiceUnavailable {
+				t.Fatalf("invalid/unreadable record returned a successful page: %+v %v", got, err)
+			}
+			if kind != "read-failure" && !errors.Is(err, errMultipartListingIdentity) {
+				t.Fatalf("identity error: %v", err)
+			}
+			report, err := z.multipartPreflight(t.Context())
+			if err != nil || report.Complete || report.Ready || report.LegacyUploads != 0 {
+				t.Fatalf("invalid/unreadable record counted as historical: %+v %v", report, err)
+			}
+		})
+	}
+}
+
+func TestMultipartListingRestart(t *testing.T) {
+	ctx, cancel := context.WithCancel(t.Context())
+	obj, dirs, err := prepareErasure(ctx, 4)
+	if err != nil {
+		cancel()
+		t.Fatal(err)
+	}
+	t.Cleanup(func() { cancel(); obj.Shutdown(context.Background()); removeRoots(dirs) })
+	const bucket, key = "multipart-restart", "dir/new"
+	if err := obj.MakeBucket(t.Context(), bucket, MakeBucketOptions{}); err != nil {
+		t.Fatal(err)
+	}
+	mp, err := obj.NewMultipartUpload(t.Context(), bucket, key, ObjectOptions{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	cancel()
+	if err := obj.Shutdown(context.Background()); err != nil {
+		t.Fatal(err)
+	}
+	reopened, _, err := initObjectLayer(t.Context(), mustGetPoolEndpoints(0, dirs...))
+	if err != nil {
+		t.Fatal(err)
+	}
+	obj = reopened
+	if _, cached := obj.(*erasureServerPools).mpCache.Load(mp.UploadID); cached {
+		t.Fatal("restart unexpectedly preserved the upload cache")
+	}
+	got, err := obj.ListMultipartUploads(t.Context(), bucket, "dir/", "", "", "", 10)
+	if err != nil {
+		t.Fatal(err)
+	}
+	requireMultipartUploadKeys(t, got, key)
+	if got.Uploads[0].UploadID != mp.UploadID {
+		t.Fatal("restart changed upload identity")
+	}
+}
+
+func TestMultipartListingConflictingIdentityCopies(t *testing.T) {
+	for _, oldCopies := range []int{1, 3} {
+		z, set, bucket := multipartListingFixture(t)
+		mp, err := z.NewMultipartUpload(t.Context(), bucket, "a", ObjectOptions{})
+		if err != nil {
+			t.Fatal(err)
+		}
+		path := set.getUploadIDDir(bucket, "a", mp.UploadID)
+		for _, disk := range set.getDisks()[:oldCopies] {
+			fi, err := disk.ReadVersion(t.Context(), bucket, minioMetaMultipartBucket, path, "", ReadOptions{})
+			if err != nil {
+				t.Fatal(err)
+			}
+			removeMultipartIdentity(fi.Metadata)
+			if err := disk.WriteMetadata(t.Context(), bucket, minioMetaMultipartBucket, path, fi); err != nil {
+				t.Fatal(err)
+			}
+		}
+		got, err := z.ListMultipartUploads(t.Context(), bucket, "", "", "", "", 10)
+		if !errors.Is(err, errMultipartListingIdentity) || len(got.Uploads) != 0 {
+			t.Fatalf("%d contradictory copies returned a successful page: %+v %v", oldCopies, got, err)
+		}
+	}
+}
+
+func TestMultipartListingUnsupportedStoredID(t *testing.T) {
+	for _, historical := range []bool{false, true} {
+		z, set, bucket := multipartListingFixture(t)
+		mp, err := z.NewMultipartUpload(t.Context(), bucket, "a", ObjectOptions{})
+		if err != nil {
+			t.Fatal(err)
+		}
+		oldPath := set.getUploadIDDir(bucket, "a", mp.UploadID)
+		unsupportedPath := pathJoin(set.getMultipartSHADir(bucket, "a"), "unsupported-id")
+		for _, disk := range set.getDisks() {
+			fi, err := disk.ReadVersion(t.Context(), bucket, minioMetaMultipartBucket, oldPath, "", ReadOptions{})
+			if err != nil {
+				t.Fatal(err)
+			}
+			if historical {
+				removeMultipartIdentity(fi.Metadata)
+			}
+			if err := disk.WriteMetadata(t.Context(), bucket, minioMetaMultipartBucket, unsupportedPath, fi); err != nil {
+				t.Fatal(err)
+			}
+			if err := disk.Delete(t.Context(), minioMetaMultipartBucket, oldPath, DeleteOptions{Recursive: true}); err != nil {
+				t.Fatal(err)
+			}
+		}
+		got, err := z.ListMultipartUploads(t.Context(), bucket, "", "", "", "", 10)
+		if historical {
+			if err != nil || len(got.Uploads) != 0 {
+				t.Fatalf("unidentified historical ID: %+v %v", got, err)
+			}
+		} else if !errors.Is(err, errMultipartListingIdentity) {
+			t.Fatalf("invalid new ID silently treated as historical: %+v %v", got, err)
+		}
+	}
+}

cmd/erasure-multipart.go

@@ -414,7 +414,7 @@ func paginateMultipartUploads(uploads []MultipartInfo, prefix, keyMarker, upload
 }
 
 // listMultipartUploadsExact preserves the hashed exact-object lookup used by
-// multipart write placement and by rolling-upgrade legacy mode.
+// multipart write placement. Public listing always uses the durable scan.
 func (er erasureObjects) listMultipartUploadsExact(ctx context.Context, bucket, object, keyMarker, uploadIDMarker, delimiter string, maxUploads int) (result ListMultipartsInfo, err error) {
 	auditObjectErasureSet(ctx, "ListMultipartUploads", object, &er)
 
@@ -527,13 +527,10 @@ func (er erasureObjects) ListMultipartUploads(ctx context.Context, bucket, prefi
 		return ListMultipartsInfo{}, err
 	}
 	defer scan.close()
-	uploads, legacy, err := er.scanMultipartUploads(scan, bucket, 0, 0)
+	uploads, err := er.scanMultipartUploads(scan, bucket, 0, 0)
 	if err != nil {
 		return ListMultipartsInfo{}, err
 	}
-	if legacy {
-		return ListMultipartsInfo{}, errMultipartListingLegacy
-	}
 	return paginateMultipartUploads(uploads, prefix, keyMarker, uploadIDMarker, delimiter, maxUploads), nil
 }
 
@@ -1788,11 +1785,9 @@ func (er erasureObjects) CompleteMultipartUpload(ctx context.Context, bucket str
 	return fi.ToObjectInfo(bucket, object, opts.Versioned || opts.VersionSuspended), nil
 }
 
-// abortMultipartUpload retains read-quorum validation and best-effort cleanup
-// in legacy mode. Strict mode requires majority deletion acknowledgements and
-// permits retrying remnants below read quorum. Neither mode fences creation
-// writes still executing after a storage timeout.
-func (er erasureObjects) abortMultipartUpload(ctx context.Context, bucket, object, uploadID string, opts ObjectOptions, legacy bool) (bool, error) {
+// abortMultipartUpload retains read-quorum validation and best-effort cleanup.
+// It does not fence creation writes still executing after a storage timeout.
+func (er erasureObjects) abortMultipartUpload(ctx context.Context, bucket, object, uploadID string, opts ObjectOptions) (bool, error) {
 	if !opts.NoAuditLog {
 		auditObjectErasureSet(ctx, "AbortMultipartUpload", object, &er)
 	}
@@ -1804,70 +1799,19 @@ func (er erasureObjects) abortMultipartUpload(ctx context.Context, bucket, objec
 	if !ok || internalID == "" || internalID == "." || internalID == ".." || strings.ContainsAny(internalID, "/\\") {
 		return false, InvalidUploadID{Bucket: bucket, Object: object, UploadID: uploadID}
 	}
-	if legacy {
-		// Keep the released read-quorum and best-effort cleanup behavior.
-		// The upload ID safety check above applies to both modes.
-		defer er.deleteAll(ctx, minioMetaMultipartBucket, er.getUploadIDDir(bucket, object, uploadID))
-		_, _, err := er.checkUploadIDExists(ctx, bucket, object, uploadID, false)
-		err = toObjectErr(err, bucket, object, uploadID)
-		if _, absent := err.(InvalidUploadID); absent {
-			return false, nil
-		}
-		return err == nil, err
-	}
-	disks := er.getDisks()
-	uploadPath := er.getUploadIDDir(bucket, object, uploadID)
-	_, errs := readAllFileInfo(ctx, disks, bucket, minioMetaMultipartBucket, uploadPath, "", false, false)
-	quorum := er.setDriveCount/2 + 1
-	found, absent := false, 0
-	observed := make([]bool, len(disks))
-	for i, err := range errs {
-		switch {
-		case err == nil, errors.Is(err, errFileCorrupt):
-			found = true
-			observed[i] = true
-		case errors.Is(err, errFileNotFound), errors.Is(err, errFileVersionNotFound):
-			absent++
-		}
-	}
-	if absent >= quorum && !found {
+	defer er.deleteAll(ctx, minioMetaMultipartBucket, er.getUploadIDDir(bucket, object, uploadID))
+	_, _, err = er.checkUploadIDExists(ctx, bucket, object, uploadID, false)
+	err = toObjectErr(err, bucket, object, uploadID)
+	if _, absent := err.(InvalidUploadID); absent {
 		return false, nil
 	}
-	if !found {
-		return false, toObjectErr(errErasureReadQuorum, bucket, object, uploadID)
-	}
-	g := errgroup.WithNErrs(len(disks))
-	for i, disk := range disks {
-		g.Go(func() error {
-			if disk == nil {
-				return errDiskNotFound
-			}
-			err := disk.Delete(ctx, minioMetaMultipartBucket, uploadPath, DeleteOptions{Recursive: true, Immediate: false})
-			if errors.Is(err, errFileNotFound) || errors.Is(err, errFileVersionNotFound) {
-				return nil
-			}
-			return err
-		}, i)
-	}
-	deleteErrs := g.Wait()
-	if err := reduceWriteQuorumErrs(ctx, deleteErrs, nil, quorum); err != nil {
-		return true, toObjectErr(err, bucket, object, uploadID)
-	}
-	if absent >= quorum {
-		// Missing disks must not mask a failed cleanup of known remnants.
-		for i, found := range observed {
-			if found && deleteErrs[i] != nil {
-				return true, toObjectErr(errErasureWriteQuorum, bucket, object, uploadID)
-			}
-		}
-	}
-	return true, nil
+	return err == nil, err
 }
 
-// AbortMultipartUpload cancels an upload using the configured mode. Offline
-// part data may still need stale-upload cleanup after its drives return.
+// AbortMultipartUpload cancels an upload using read-quorum validation.
+// Offline part data may still need stale-upload cleanup after its drives return.
 func (er erasureObjects) AbortMultipartUpload(ctx context.Context, bucket, object, uploadID string, opts ObjectOptions) (err error) {
-	found, err := er.abortMultipartUpload(ctx, bucket, object, uploadID, opts, globalAPIConfig.getMultipartListingLegacy())
+	found, err := er.abortMultipartUpload(ctx, bucket, object, uploadID, opts)
 	if err != nil {
 		return err
 	}

cmd/erasure-server-pool.go

@@ -1916,9 +1916,6 @@ func (z *erasureServerPools) ListMultipartUploads(ctx context.Context, bucket, p
 	if _, err := z.GetBucketInfo(ctx, bucket, BucketOptions{}); err != nil {
 		return ListMultipartsInfo{}, toObjectErr(err, bucket)
 	}
-	if globalAPIConfig.getMultipartListingLegacy() {
-		return z.listMultipartUploadsLegacy(ctx, bucket, prefix, keyMarker, uploadIDMarker, delimiter, maxUploads)
-	}
 	scan, err := startMultipartScan(ctx, false)
 	if err != nil {
 		return ListMultipartsInfo{}, err
@@ -1926,70 +1923,22 @@ func (z *erasureServerPools) ListMultipartUploads(ctx context.Context, bucket, p
 	defer scan.close()
 
 	var uploads []MultipartInfo
-	var keyless bool
 	for idx, pool := range z.serverPools {
 		if z.IsSuspended(idx) {
 			continue
 		}
-		poolUploads, poolKeyless, err := pool.scanMultipartUploads(scan, bucket, idx)
+		poolUploads, err := pool.scanMultipartUploads(scan, bucket, idx)
 		if err != nil {
 			return ListMultipartsInfo{}, err
 		}
 		uploads = append(uploads, poolUploads...)
-		keyless = keyless || poolKeyless
 	}
 
-	// The old format cannot be enumerated authoritatively. Migration mode is
-	// explicit: another bucket must never silently change this API's semantics.
-	if keyless {
-		return ListMultipartsInfo{}, errMultipartListingLegacy
-	}
+	// Confirmed historical records lack a recoverable bucket/key and are
+	// omitted by the scan. They do not block listing identifiable uploads.
 	return paginateMultipartUploads(uploads, prefix, keyMarker, uploadIDMarker, delimiter, maxUploads), nil
 }
 
-func (z *erasureServerPools) listMultipartUploadsLegacy(ctx context.Context, bucket, prefix, keyMarker, uploadIDMarker, delimiter string, maxUploads int) (ListMultipartsInfo, error) {
-	poolResult := ListMultipartsInfo{}
-	poolResult.MaxUploads = maxUploads
-	poolResult.KeyMarker = keyMarker
-	poolResult.Prefix = prefix
-	poolResult.Delimiter = delimiter
-
-	// if no prefix provided, return the list from cache
-	if prefix == "" {
-		if _, err := z.GetBucketInfo(ctx, bucket, BucketOptions{}); err != nil {
-			return ListMultipartsInfo{}, toObjectErr(err, bucket)
-		}
-
-		z.mpCache.Range(func(_ string, mp MultipartInfo) bool {
-			if mp.Bucket == bucket {
-				poolResult.Uploads = append(poolResult.Uploads, mp)
-			}
-			return true
-		})
-		sort.Slice(poolResult.Uploads, func(i int, j int) bool {
-			return poolResult.Uploads[i].Initiated.Before(poolResult.Uploads[j].Initiated)
-		})
-		return poolResult, nil
-	}
-
-	if z.SinglePool() {
-		return z.serverPools[0].getHashedSet(prefix).listMultipartUploadsExact(ctx, bucket, prefix, keyMarker, uploadIDMarker, delimiter, maxUploads)
-	}
-
-	for idx, pool := range z.serverPools {
-		if z.IsSuspended(idx) {
-			continue
-		}
-		result, err := pool.getHashedSet(prefix).listMultipartUploadsExact(ctx, bucket, prefix, keyMarker, uploadIDMarker, delimiter, maxUploads)
-		if err != nil {
-			return result, err
-		}
-		poolResult.Uploads = append(poolResult.Uploads, result.Uploads...)
-	}
-
-	return poolResult, nil
-}
-
 // Initiate a new multipart upload on a hashedSet based on object name.
 func (z *erasureServerPools) NewMultipartUpload(ctx context.Context, bucket, object string, opts ObjectOptions) (mp *NewMultipartUploadResult, err error) {
 	if err := checkNewMultipartArgs(ctx, bucket, object); err != nil {
@@ -2199,28 +2148,15 @@ func (z *erasureServerPools) AbortMultipartUpload(ctx context.Context, bucket, o
 	ctx = lkctx.Context()
 	defer lk.Unlock(lkctx)
 
-	legacy := globalAPIConfig.getMultipartListingLegacy()
-	found := false
-	var firstErr error
 	for idx, pool := range z.serverPools {
 		if z.IsSuspended(idx) {
 			continue
 		}
-		poolFound, err := pool.getHashedSet(object).abortMultipartUpload(ctx, bucket, object, uploadID, opts, legacy)
-		if legacy && (poolFound || err != nil) {
-			// Match the released first-matching-pool behavior.
+		found, err := pool.getHashedSet(object).abortMultipartUpload(ctx, bucket, object, uploadID, opts)
+		if found || err != nil {
+			// Preserve the default first-matching-pool behavior.
 			return err
 		}
-		found = found || poolFound
-		if err != nil && firstErr == nil {
-			firstErr = err
-		}
-	}
-	if firstErr != nil {
-		return firstErr
-	}
-	if found {
-		return nil
 	}
 	return InvalidUploadID{
 		Bucket:   bucket,

cmd/erasure-sets.go

@@ -894,28 +894,23 @@ func (s *erasureSets) ListMultipartUploads(ctx context.Context, bucket, prefix,
 		return ListMultipartsInfo{}, err
 	}
 	defer scan.close()
-	uploads, legacy, err := s.scanMultipartUploads(scan, bucket, 0)
+	uploads, err := s.scanMultipartUploads(scan, bucket, 0)
 	if err != nil {
 		return ListMultipartsInfo{}, err
 	}
-	if legacy {
-		return ListMultipartsInfo{}, errMultipartListingLegacy
-	}
 	return paginateMultipartUploads(uploads, prefix, keyMarker, uploadIDMarker, delimiter, maxUploads), nil
 }
 
-func (s *erasureSets) scanMultipartUploads(scan *multipartScan, bucket string, poolIdx int) ([]MultipartInfo, bool, error) {
+func (s *erasureSets) scanMultipartUploads(scan *multipartScan, bucket string, poolIdx int) ([]MultipartInfo, error) {
 	var uploads []MultipartInfo
-	var keyless bool
 	for i, set := range s.sets {
-		setUploads, setKeyless, err := set.scanMultipartUploads(scan, bucket, poolIdx, i)
+		setUploads, err := set.scanMultipartUploads(scan, bucket, poolIdx, i)
 		if err != nil {
-			return nil, false, err
+			return nil, err
 		}
 		uploads = append(uploads, setUploads...)
-		keyless = keyless || setKeyless
 	}
-	return uploads, keyless, nil
+	return uploads, nil
 }
 
 func (s *erasureSets) listMultipartUploadsExact(ctx context.Context, bucket, object string) (ListMultipartsInfo, error) {

cmd/handler-api.go

@@ -50,7 +50,6 @@ type apiConfig struct {
 	transitionWorkers      int
 
 	staleUploadsExpiry          time.Duration
-	multipartListingStrict      bool
 	staleUploadsCleanupInterval time.Duration
 	deleteCleanupInterval       time.Duration
 	enableODirect               bool
@@ -182,7 +181,6 @@ func (t *apiConfig) init(cfg api.Config, setDriveCounts []int, legacy bool) {
 	t.transitionWorkers = cfg.TransitionWorkers
 
 	t.staleUploadsExpiry = cfg.StaleUploadsExpiry
-	t.multipartListingStrict = cfg.MultipartListing == "strict"
 	t.deleteCleanupInterval = cfg.DeleteCleanupInterval
 	t.enableODirect = cfg.EnableODirect
 	t.gzipObjects = cfg.GzipObjects
@@ -208,12 +206,6 @@ func (t *apiConfig) odirectEnabled() bool {
 	return t.enableODirect
 }
 
-func (t *apiConfig) getMultipartListingLegacy() bool {
-	t.mu.RLock()
-	defer t.mu.RUnlock()
-	return !t.multipartListingStrict
-}
-
 func (t *apiConfig) shouldGzipObjects() bool {
 	t.mu.RLock()
 	defer t.mu.RUnlock()

cmd/list-multipart-uploads-compat_test.go

@@ -19,7 +19,6 @@ package cmd
 
 import (
 	"bytes"
-	"errors"
 	"fmt"
 	"slices"
 	"testing"
@@ -47,7 +46,7 @@ func TestListMultipartUploadsS3Compatibility(t *testing.T) {
 		t.Fatal(err)
 	}
 	z := obj.(*erasureServerPools)
-	setMultipartListingTestMode(t, false)
+
 	t.Cleanup(func() {
 		z.Shutdown(t.Context())
 		removeRoots(dirs)
@@ -182,8 +181,8 @@ func TestListMultipartUploadsS3Compatibility(t *testing.T) {
 	}
 
 	// Simulate an upload written by a pre-upgrade server. Its key cannot be
-	// recovered by scanning the hashed namespace. Strict listing must fail;
-	// the old path is available only through an explicit migration setting.
+	// recovered by scanning the hashed namespace. Omit only that record, and
+	// preserve normal operations when its bucket, key and upload ID are known.
 	legacyObject := objects[1]
 	er := sets.getHashedSet(legacyObject)
 	fi, metadata, err := er.checkUploadIDExists(t.Context(), bucket, legacyObject, uploadIDs[legacyObject], true)
@@ -198,16 +197,25 @@ func TestListMultipartUploadsS3Compatibility(t *testing.T) {
 		er.getUploadIDDir(bucket, legacyObject, uploadIDs[legacyObject]), metadata, fi.WriteQuorum(er.defaultWQuorum())); err != nil {
 		t.Fatal(err)
 	}
-	_, err = z.ListMultipartUploads(t.Context(), bucket, legacyObject, "", "", "", 100)
-	if !errors.Is(err, errMultipartListingLegacy) {
-		t.Fatalf("legacy strict listing: %v", err)
-	}
-	setMultipartListingTestMode(t, true)
 	legacy, err := z.ListMultipartUploads(t.Context(), bucket, legacyObject, "", "", "", 100)
 	if err != nil {
 		t.Fatal(err)
 	}
-	requireMultipartUploadKeys(t, legacy, legacyObject)
+	requireMultipartUploadKeys(t, legacy)
+	remaining, err := z.ListMultipartUploads(t.Context(), bucket, "", "", "", "", 100)
+	if err != nil {
+		t.Fatal(err)
+	}
+	requireMultipartUploadKeys(t, remaining, objects[2:]...)
+	part, err = z.PutObjectPart(t.Context(), bucket, legacyObject, uploadIDs[legacyObject], 1,
+		mustGetPutObjReader(t, bytes.NewBufferString("old part"), 8, "", ""), ObjectOptions{})
+	if err != nil {
+		t.Fatalf("continue historical upload: %v", err)
+	}
+	if _, err = z.CompleteMultipartUpload(t.Context(), bucket, legacyObject, uploadIDs[legacyObject],
+		[]CompletePart{{PartNumber: 1, ETag: part.ETag}}, ObjectOptions{}); err != nil {
+		t.Fatalf("complete historical upload: %v", err)
+	}
 }
 
 func TestPaginateMultipartUploads(t *testing.T) {
@@ -260,7 +268,7 @@ func TestPaginateMultipartUploads(t *testing.T) {
 
 func TestListMultipartUploadsGlobalPageAcrossPools(t *testing.T) {
 	z, bucket := consistencyPools(t)
-	setMultipartListingTestMode(t, false)
+
 	objects := []string{"a/one", "b/two", "c/three", "d/four"}
 	for i, object := range objects {
 		if _, err := z.serverPools[i%len(z.serverPools)].NewMultipartUpload(t.Context(), bucket, object, ObjectOptions{}); err != nil {