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https://github.com/etcd-io/etcd.git
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75 lines
1.6 KiB
Go
75 lines
1.6 KiB
Go
// +build linux,amd64
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package btrfs
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import (
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"fmt"
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"os"
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"runtime"
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"syscall"
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"unsafe"
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"github.com/coreos/etcd/log"
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)
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const (
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// from Linux/include/uapi/linux/magic.h
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BTRFS_SUPER_MAGIC = 0x9123683E
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// from Linux/include/uapi/linux/fs.h
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FS_NOCOW_FL = 0x00800000
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FS_IOC_GETFLAGS = 0x80086601
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FS_IOC_SETFLAGS = 0x40086602
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)
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// IsBtrfs checks whether the file is in btrfs
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func IsBtrfs(path string) bool {
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// btrfs is linux-only filesystem
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// exit on other platforms
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if runtime.GOOS != "linux" {
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return false
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}
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var buf syscall.Statfs_t
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if err := syscall.Statfs(path, &buf); err != nil {
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log.Warnf("Failed to statfs: %v", err)
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return false
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}
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log.Debugf("The type of path %v is %v", path, buf.Type)
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if buf.Type != BTRFS_SUPER_MAGIC {
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return false
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}
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log.Infof("The path %v is in btrfs", path)
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return true
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}
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// SetNOCOWFile sets NOCOW flag for file
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func SetNOCOWFile(path string) error {
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file, err := os.Open(path)
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if err != nil {
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return err
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}
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defer file.Close()
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fileinfo, err := file.Stat()
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if err != nil {
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return err
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}
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if fileinfo.IsDir() {
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return fmt.Errorf("skip directory")
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}
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if fileinfo.Size() != 0 {
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return fmt.Errorf("skip nonempty file")
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}
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var attr int
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if _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, file.Fd(), FS_IOC_GETFLAGS, uintptr(unsafe.Pointer(&attr))); errno != 0 {
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return errno
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}
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attr |= FS_NOCOW_FL
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if _, _, errno := syscall.Syscall(syscall.SYS_IOCTL, file.Fd(), FS_IOC_SETFLAGS, uintptr(unsafe.Pointer(&attr))); errno != 0 {
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return errno
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}
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log.Infof("Set NOCOW to path %v succeeded", path)
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return nil
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}
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