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pkg/fileutil: fix F_OFD_ constants #12444

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Nov 3, 2020
Merged

pkg/fileutil: fix F_OFD_ constants #12444

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15 changes: 5 additions & 10 deletions pkg/fileutil/lock_linux.go
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Original file line number Diff line number Diff line change
Expand Up @@ -21,19 +21,14 @@ import (
"io"
"os"
"syscall"

"golang.org/x/sys/unix"
)

// This used to call syscall.Flock() but that call fails with EBADF on NFS.
// An alternative is lockf() which works on NFS but that call lets a process lock
// the same file twice. Instead, use Linux's non-standard open file descriptor
// locks which will block if the process already holds the file lock.
//
// constants from /usr/include/bits/fcntl-linux.h
const (
F_OFD_GETLK = 37
F_OFD_SETLK = 37
F_OFD_SETLKW = 38
)

var (
wrlck = syscall.Flock_t{
Expand All @@ -50,7 +45,7 @@ var (
func init() {
// use open file descriptor locks if the system supports it
getlk := syscall.Flock_t{Type: syscall.F_RDLCK}
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Why do you need to use dynamic probing for OFD locks ? This file is for Linux only.
Are OFD locks new in Linux?

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F_OFD_ locks are there since Linux kernel 3.15.

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Do you still support 3.15 and older?

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Do you still support 3.15 and older?

@joakim-tjernlund I do not know about that, I am just a contributor here. Given the fact that this package is used by other software, I think it make sense to support older kernels.

if err := syscall.FcntlFlock(0, F_OFD_GETLK, &getlk); err == nil {
if err := syscall.FcntlFlock(0, unix.F_OFD_GETLK, &getlk); err == nil {
linuxTryLockFile = ofdTryLockFile
linuxLockFile = ofdLockFile
}
Expand All @@ -67,7 +62,7 @@ func ofdTryLockFile(path string, flag int, perm os.FileMode) (*LockedFile, error
}

flock := wrlck
if err = syscall.FcntlFlock(f.Fd(), F_OFD_SETLK, &flock); err != nil {
if err = syscall.FcntlFlock(f.Fd(), unix.F_OFD_SETLK, &flock); err != nil {
f.Close()
if err == syscall.EWOULDBLOCK {
err = ErrLocked
Expand All @@ -88,7 +83,7 @@ func ofdLockFile(path string, flag int, perm os.FileMode) (*LockedFile, error) {
}

flock := wrlck
err = syscall.FcntlFlock(f.Fd(), F_OFD_SETLKW, &flock)
err = syscall.FcntlFlock(f.Fd(), unix.F_OFD_SETLKW, &flock)
if err != nil {
f.Close()
return nil, err
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