add necessary protection err, fileInfo slice reads and writes (#18854)

protection was in place. However, it covered only some
areas, so we re-arranged the code to ensure we could hold
locks properly.

Along with this, remove the DataShardFix code altogether,
in deployments with many drive replacements, this can affect
and lead to quorum loss.

cmd/erasure-metadata.go

@@ -374,17 +374,6 @@ func findFileInfoInQuorum(ctx context.Context, metaArr []FileInfo, modTime time.
 	return FileInfo{}, errErasureReadQuorum
 }
 
-func pickValidDiskTimeWithQuorum(metaArr []FileInfo, quorum int) time.Time {
-	diskMTimes := listObjectDiskMtimes(metaArr)
-
-	diskMTime, diskMaxima := commonTimeAndOccurence(diskMTimes, shardDiskTimeDelta)
-	if diskMaxima >= quorum {
-		return diskMTime
-	}
-
-	return timeSentinel
-}
-
 // pickValidFileInfo - picks one valid FileInfo content and returns from a
 // slice of FileInfo.
 func pickValidFileInfo(ctx context.Context, metaArr []FileInfo, modTime time.Time, etag string, quorum int) (FileInfo, error) {