avoid a crash in crawler when lifecycle is not initialized (#11170)

Bonus for static buffers use bytes.NewReader instead of
bytes.NewBuffer, to use a more reader friendly implementation

cmd/erasure-common.go

@@ -19,6 +19,7 @@ package cmd
 import (
 	"context"
 	"path"
+	"sort"
 	"sync"
 
 	"github.com/minio/minio/pkg/sync/errgroup"
@@ -37,6 +38,65 @@ func (er erasureObjects) getLoadBalancedLocalDisks() (newDisks []StorageAPI) {
 	return newDisks
 }
 
+type sortSlices struct {
+	disks []StorageAPI
+	infos []DiskInfo
+}
+
+type sortByOther sortSlices
+
+func (sbo sortByOther) Len() int {
+	return len(sbo.disks)
+}
+
+func (sbo sortByOther) Swap(i, j int) {
+	sbo.disks[i], sbo.disks[j] = sbo.disks[j], sbo.disks[i]
+	sbo.infos[i], sbo.infos[j] = sbo.infos[j], sbo.infos[i]
+}
+
+func (sbo sortByOther) Less(i, j int) bool {
+	return sbo.infos[i].UsedInodes < sbo.infos[j].UsedInodes
+}
+
+func (er erasureObjects) getOnlineDisksSortedByUsedInodes() (newDisks []StorageAPI) {
+	disks := er.getDisks()
+	var wg sync.WaitGroup
+	var mu sync.Mutex
+	var infos []DiskInfo
+	for _, i := range hashOrder(UTCNow().String(), len(disks)) {
+		i := i
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			if disks[i-1] == nil {
+				return
+			}
+			di, err := disks[i-1].DiskInfo(context.Background())
+			if err != nil || di.Healing {
+
+				// - Do not consume disks which are not reachable
+				//   unformatted or simply not accessible for some reason.
+				//
+				// - Do not consume disks which are being healed
+				//
+				// - Future: skip busy disks
+				return
+			}
+
+			mu.Lock()
+			newDisks = append(newDisks, disks[i-1])
+			infos = append(infos, di)
+			mu.Unlock()
+		}()
+	}
+	wg.Wait()
+
+	slices := sortSlices{newDisks, infos}
+	sort.Sort(sortByOther(slices))
+
+	return slices.disks
+}
+
 func (er erasureObjects) getOnlineDisks() (newDisks []StorageAPI) {
 	disks := er.getDisks()
 	var wg sync.WaitGroup