fix: preserve version state across late rollback and nested mutations

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

cmd/erasure-metadata.go

@@ -19,7 +19,6 @@ package cmd
 
 import (
 	"context"
-	"encoding/hex"
 	"fmt"
 	"sort"
 	"strings"
@@ -28,8 +27,6 @@ import (
 	"github.com/minio/minio/internal/amztime"
 	"github.com/minio/minio/internal/bucket/lifecycle"
 	"github.com/minio/minio/internal/bucket/replication"
-	"github.com/minio/minio/internal/crypto"
-	"github.com/minio/minio/internal/hash/sha256"
 	xhttp "github.com/minio/minio/internal/http"
 	"github.com/pgsty/silo-pkg/v3/sync/errgroup"
 )
@@ -319,68 +316,48 @@ func findFileInfoInQuorum(ctx context.Context, metaArr []FileInfo, modTime time.
 	if quorum < 1 {
 		return FileInfo{}, InsufficientReadQuorum{Err: errErasureReadQuorum, Type: RQInsufficientOnlineDrives}
 	}
-	metaHashes := make([]string, len(metaArr))
-	h := sha256.New()
+	// Group by exact logical state rather than a layout-only hash. There are
+	// at most one erasure set's worth of candidates; healthy objects compare
+	// against a single representative without hashing or a second XL decode.
+	groups := make([]int, len(metaArr))
+	representatives := make([]int, 0, len(metaArr))
+	counts := make([]int, len(metaArr)+1)
 	for i, meta := range metaArr {
 		if !meta.IsValid() {
 			continue
 		}
-		etagOnly := modTime.Equal(timeSentinel) && (etag != "" && etag == meta.Metadata["etag"])
-		mtimeValid := meta.ModTime.Equal(modTime)
-		if mtimeValid || etagOnly {
-			fmt.Fprintf(h, "%v", meta.XLV1)
-			for _, part := range meta.Parts {
-				fmt.Fprintf(h, "part.%d", part.Number)
-				fmt.Fprintf(h, "part.%d", part.Size)
-			}
-			// Previously we checked if we had quorum on DataDir value.
-			// We have removed this check to allow reading objects with different DataDir
-			// values in a few drives (due to a rebalance-stop race bug)
-			// provided their their etags or ModTimes match.
-
-			if !meta.Deleted && meta.Size != 0 {
-				fmt.Fprintf(h, "%v+%v", meta.Erasure.DataBlocks, meta.Erasure.ParityBlocks)
-				fmt.Fprintf(h, "%v", meta.Erasure.Distribution)
-			}
-
-			if meta.IsRemote() {
-				// ILM transition fields
-				fmt.Fprint(h, meta.TransitionStatus)
-				fmt.Fprint(h, meta.TransitionTier)
-				fmt.Fprint(h, meta.TransitionedObjName)
-				fmt.Fprint(h, meta.TransitionVersionID)
-			}
-
-			// If metadata says encrypted, ask for it in quorum.
-			if etyp, ok := crypto.IsEncrypted(meta.Metadata); ok {
-				fmt.Fprint(h, etyp)
-			}
-
-			// If compressed, look for compressed FileInfo only
-			if meta.IsCompressed() {
-				fmt.Fprint(h, meta.Metadata[ReservedMetadataPrefix+"compression"])
-			}
-
-			metaHashes[i] = hex.EncodeToString(h.Sum(nil))
-			h.Reset()
-		}
-	}
-
-	metaHashCountMap := make(map[string]int)
-	for _, hash := range metaHashes {
-		if hash == "" {
+		etagOnly := modTime.Equal(timeSentinel) && etag != "" && etag == meta.Metadata["etag"]
+		if !meta.ModTime.Equal(modTime) && !etagOnly {
 			continue
 		}
-		metaHashCountMap[hash]++
-	}
-
-	maxHash := ""
-	maxCount := 0
-	for hash, count := range metaHashCountMap {
-		if count > maxCount {
-			maxCount = count
-			maxHash = hash
+		group := 0
+		for j, representative := range representatives {
+			if sameFileInfoVersion(metaArr[representative], meta) {
+				group = j + 1
+				break
+			}
 		}
+		if group == 0 {
+			representatives = append(representatives, i)
+			group = len(representatives)
+		}
+		groups[i] = group
+		counts[group]++
+	}
+	maxGroup, maxCount := 0, 0
+	tied := false
+	for group, count := range counts {
+		if group == 0 {
+			continue
+		}
+		if count > maxCount {
+			maxGroup, maxCount, tied = group, count, false
+		} else if count == maxCount {
+			tied = true
+		}
+	}
+	if tied {
+		return FileInfo{}, InsufficientReadQuorum{Err: errErasureReadQuorum, Type: RQInconsistentMeta}
 	}
 
 	if maxCount < quorum {
@@ -397,8 +374,8 @@ func findFileInfoInQuorum(ctx context.Context, metaArr []FileInfo, modTime time.
 	otherPropsMap := make(counterMap[objProps])
 	var candidate FileInfo
 	var found bool
-	for i, hash := range metaHashes {
-		if hash == maxHash {
+	for i, group := range groups {
+		if group == maxGroup {
 			if metaArr[i].IsValid() {
 				if !found {
 					candidate = metaArr[i]