forked from TrueCloudLab/frostfs-s3-gw
69 lines
2.5 KiB
Go
69 lines
2.5 KiB
Go
// +build !linux,!netbsd,!freebsd,!darwin,!openbsd
|
|
|
|
/*
|
|
* Minio Cloud Storage, (C) 2019-2020 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 disk
|
|
|
|
import (
|
|
"os"
|
|
)
|
|
|
|
// OpenBSD, Windows, and illumos do not support O_DIRECT.
|
|
// On Windows there is no documentation on disabling O_DIRECT.
|
|
// For these systems we do not attempt to build the 'directio' dependency since
|
|
// the O_DIRECT symbol may not be exposed resulting in a failed build.
|
|
//
|
|
//
|
|
// On illumos an explicit O_DIRECT flag is not necessary for two primary
|
|
// reasons. Note that ZFS is effectively the default filesystem on illumos
|
|
// systems.
|
|
//
|
|
// One benefit of using DirectIO on Linux is that the page cache will not be
|
|
// polluted with single-access data. The ZFS read cache (ARC) is scan-resistant
|
|
// so there is no risk of polluting the entire cache with data accessed once.
|
|
// Another goal of DirectIO is to minimize the mutation of data by the kernel
|
|
// before issuing IO to underlying devices. ZFS users often enable features like
|
|
// compression and checksumming which currently necessitates mutating data in
|
|
// the kernel.
|
|
//
|
|
// DirectIO semantics for a filesystem like ZFS would be quite different than
|
|
// the semantics on filesystems like XFS, and these semantics are not
|
|
// implemented at this time.
|
|
// For more information on why typical DirectIO semantics do not apply to ZFS
|
|
// see this ZFS-on-Linux commit message:
|
|
// https://github.com/openzfs/zfs/commit/a584ef26053065f486d46a7335bea222cb03eeea
|
|
|
|
// OpenFileDirectIO wrapper around os.OpenFile nothing special
|
|
func OpenFileDirectIO(filePath string, flag int, perm os.FileMode) (*os.File, error) {
|
|
return os.OpenFile(filePath, flag, perm)
|
|
}
|
|
|
|
// DisableDirectIO is a no-op
|
|
func DisableDirectIO(f *os.File) error {
|
|
return nil
|
|
}
|
|
|
|
// AlignedBlock simply returns an unaligned buffer
|
|
// for systems that do not support DirectIO.
|
|
func AlignedBlock(BlockSize int) []byte {
|
|
return make([]byte, BlockSize)
|
|
}
|
|
|
|
// Fdatasync is a no-op
|
|
func Fdatasync(f *os.File) error {
|
|
return nil
|
|
}
|