minio/cmd/fallocate_linux.go

// +build linux

/*
 * Minio Cloud Storage, (C) 2016 Minio, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package cmd

import "syscall"

// Fallocate uses the linux Fallocate syscall, which helps us to be
// sure that subsequent writes on a file just created will not fail,
// in addition, file allocation will be contigous on the disk
func Fallocate(fd int, offset int64, len int64) error {
	// No need to attempt fallocate for 0 length.
	if len == 0 {
		return nil
	}
	// Don't extend size of file even if offset + len is
	// greater than file size from <bits/fcntl-linux.h>.
	fallocFLKeepSize := uint32(1)
	return syscall.Fallocate(fd, fallocFLKeepSize, offset, len)
}