Revert "replace unix implementation to be the same as solaris to fix …

…an issue with glusterfs"

This reverts commit ca9f208.

bolt_unix.go

@@ -21,21 +21,16 @@ func flock(db *DB, mode os.FileMode, exclusive bool, timeout time.Duration) erro
 		} else if timeout > 0 && time.Since(t) > timeout {
 			return ErrTimeout
 		}
-		var lock syscall.Flock_t
-		lock.Start = 0
-		lock.Len = 0
-		lock.Pid = 0
-		lock.Whence = 0
-		lock.Pid = 0
+		flag := syscall.LOCK_SH
 		if exclusive {
-			lock.Type = syscall.F_WRLCK
-		} else {
-			lock.Type = syscall.F_RDLCK
+			flag = syscall.LOCK_EX
 		}
-		err := syscall.FcntlFlock(db.file.Fd(), syscall.F_SETLK, &lock)
+
+		// Otherwise attempt to obtain an exclusive lock.
+		err := syscall.Flock(int(db.file.Fd()), flag|syscall.LOCK_NB)
 		if err == nil {
 			return nil
-		} else if err != syscall.EAGAIN {
+		} else if err != syscall.EWOULDBLOCK {
 			return err
 		}
 
@@ -46,12 +41,7 @@ func flock(db *DB, mode os.FileMode, exclusive bool, timeout time.Duration) erro
 
 // funlock releases an advisory lock on a file descriptor.
 func funlock(db *DB) error {
-	var lock syscall.Flock_t
-	lock.Start = 0
-	lock.Len = 0
-	lock.Type = syscall.F_UNLCK
-	lock.Whence = 0
-	return syscall.FcntlFlock(uintptr(db.file.Fd()), syscall.F_SETLK, &lock)
+	return syscall.Flock(int(db.file.Fd()), syscall.LOCK_UN)
 }
 
 // mmap memory maps a DB's data file.