| // Copyright 2015 CoreOS, 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. |
| |
| // +build linux |
| |
| package fileutil |
| |
| import ( |
| "os" |
| "syscall" |
| ) |
| |
| // Preallocate tries to allocate the space for given |
| // file. This operation is only supported on linux by a |
| // few filesystems (btrfs, ext4, etc.). |
| // If the operation is unsupported, no error will be returned. |
| // Otherwise, the error encountered will be returned. |
| func Preallocate(f *os.File, sizeInBytes int) error { |
| // use mode = 1 to keep size |
| // see FALLOC_FL_KEEP_SIZE |
| err := syscall.Fallocate(int(f.Fd()), 1, 0, int64(sizeInBytes)) |
| if err != nil { |
| errno, ok := err.(syscall.Errno) |
| // treat not support as nil error |
| if ok && errno == syscall.ENOTSUP { |
| return nil |
| } |
| return err |
| } |
| return nil |
| } |
