add more for volume placement

fix possible nil volume cases

weed-fs/src/pkg/storage/storage_limit.go

@@ -1,21 +1,13 @@
 package storage
 
 import (
-	"syscall"
 )
 
 type StorageLimit struct {
 	sizeLimit     uint64
-	detectedLimit uint64
 }
 
 func NewStorageLimit(desiredLimit uint64) *StorageLimit {
-	s := syscall.Statfs_t{}
-	errNo := syscall.Statfs(".", &s)
-	detected := uint64(0)
-	if errNo==nil {
-    detected = s.Bavail*uint64(s.Bsize)
-	}
-	sl := &StorageLimit{sizeLimit: desiredLimit, detectedLimit: detected}
+	sl := &StorageLimit{sizeLimit: desiredLimit}
 	return sl
 }

weed-fs/src/pkg/storage/storage_limit_test.go

@@ -1,11 +0,0 @@
-package storage
-
-import (
-    "testing"
-)
-
-func TestReadStorageLimit(t *testing.T) {
-  sl := NewStorageLimit(1000)
-  println("detected:",sl.detectedLimit)
-}
-

weed-fs/src/pkg/storage/store.go

@@ -89,11 +89,23 @@ func (s *Store) Close() {
 	}
 }
 func (s *Store) Write(i VolumeId, n *Needle) uint32 {
-	return s.volumes[i].write(n)
+  v := s.volumes[i]
+  if v!=nil{
+    return v.write(n)
+  }
+  return 0
 }
 func (s *Store) Delete(i VolumeId, n *Needle) uint32 {
-	return s.volumes[i].delete(n)
+  v := s.volumes[i]
+  if v!=nil{
+    return v.delete(n)
+  }
+  return 0
 }
 func (s *Store) Read(i VolumeId, n *Needle) (int, error) {
-	return s.volumes[i].read(n)
+  v := s.volumes[i]
+  if v!=nil{
+    return v.read(n)
+  }
+  return 0, errors.New("Not Found")
 }