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local: fix preallocate warning on Linux with ZFS

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Under Linux, rclone attempts to preallocate files for efficiency.

Before this change, pre-allocation would fail on ZFS with the error

    Failed to pre-allocate: operation not supported

After this change rclone tries a different flag combination for ZFS
then disables pre-allocate if that doesn't work.

Fixes #3066
This commit is contained in:
Nick Craig-Wood 2019-03-25 15:22:40 +00:00
parent 62681e45fb
commit 5a941cdcdc
1 changed files with 25 additions and 1 deletions
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26
backend/local/preallocate_unix.go
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@ -4,16 +4,40 @@ package local
import (
"os"
"sync/atomic"
"github.com/ncw/rclone/fs"
"golang.org/x/sys/unix"
)
var (
fallocFlags = [...]uint32{
unix.FALLOC_FL_KEEP_SIZE, // Default
unix.FALLOC_FL_KEEP_SIZE | unix.FALLOC_FL_PUNCH_HOLE, // for ZFS #3066
}
fallocFlagsIndex int32
)
// preAllocate the file for performance reasons
func preAllocate(size int64, out *os.File) error {
if size <= 0 {
return nil
}
err := unix.Fallocate(int(out.Fd()), unix.FALLOC_FL_KEEP_SIZE, 0, size)
index := atomic.LoadInt32(&fallocFlagsIndex)
again:
if index >= int32(len(fallocFlags)) {
return nil // Fallocate is disabled
}
flags := fallocFlags[index]
err := unix.Fallocate(int(out.Fd()), flags, 0, size)
if err == unix.ENOTSUP {
// Try the next flags combination
index++
atomic.StoreInt32(&fallocFlagsIndex, index)
fs.Debugf(nil, "preAllocate: got error on fallocate, trying combination %d/%d: %v", index, len(fallocFlags), err)
goto again
}
// FIXME could be doing something here
// if err == unix.ENOSPC {
// log.Printf("No space")