pkg/fs: DRY SetBucketMetadata

It had a lot of code that was the same as GetBucketMetadata, so instead
call GBM from SBM so as to reduce doing the same thing in two different
spots. Theoretically this will induce a small overhead as now at least
two calls of denormalizeBucket are made, although this shouldn't be
noticeable.

pkg/fs/fs-bucket.go

@@ -230,45 +230,27 @@ func (fs Filesystem) GetBucketMetadata(bucket string) (BucketMetadata, *probe.Er
 
 // SetBucketMetadata - set bucket metadata.
 func (fs Filesystem) SetBucketMetadata(bucket string, metadata map[string]string) *probe.Error {
-	// Input validation.
-	if !IsValidBucketName(bucket) {
-		return probe.NewError(BucketNameInvalid{Bucket: bucket})
+	bucketMetadata, err := fs.GetBucketMetadata(bucket)
+	if err != nil {
+		return err
 	}
+
 	// Save the acl.
 	acl := metadata["acl"]
 	if !IsValidBucketACL(acl) {
 		return probe.NewError(InvalidACL{ACL: acl})
-	}
-	if acl == "" {
+	} else if acl == "" {
 		acl = "private"
 	}
-	bucket = fs.denormalizeBucket(bucket)
-	bucketDir := filepath.Join(fs.path, bucket)
-	fi, e := os.Stat(bucketDir)
-	if e != nil {
-		// Check if bucket exists.
-		if os.IsNotExist(e) {
-			return probe.NewError(BucketNotFound{Bucket: bucket})
-		}
-		return probe.NewError(e)
-	}
-
-	// Critical region handle read lock.
-	fs.rwLock.RLock()
-	bucketMetadata, ok := fs.buckets.Metadata[bucket]
-	fs.rwLock.RUnlock()
-	if !ok {
-		bucketMetadata = &BucketMetadata{}
-		bucketMetadata.Name = fi.Name()
-		bucketMetadata.Created = fi.ModTime()
-	}
 	bucketMetadata.ACL = BucketACL(acl)
 
+	bucket = fs.denormalizeBucket(bucket)
+
 	// Critical region handle write lock.
 	fs.rwLock.Lock()
 	defer fs.rwLock.Unlock()
 
-	fs.buckets.Metadata[bucket] = bucketMetadata
+	fs.buckets.Metadata[bucket] = &bucketMetadata
 	if err := saveBucketsMetadata(*fs.buckets); err != nil {
 		return err.Trace(bucket)
 	}