tools: flock: add NFSv4 compatibility
This patch fixes the LEDE build on mounted NFSv4 shares.
The lock file cannot be opened in read-write mode by default, because
then we cannot use flock(1) to lock executable files.
The read-write mode for lock files is necessary on NFSv4 where
flock(2) is emulated by by fcntl() -- this situation is possible to
detect by flock(2) EBADF error.
The patch consist of the following util-linux/flock commits
http://git.kernel.org/cgit/utils/util-linux/util-linux.git/commit/?id=
eb742a1f66d5e3a7c5b43efce741c113f51bef3b
http://git.kernel.org/cgit/utils/util-linux/util-linux.git/commit/?id=
caf1ba11a367ad702fb774653daf9ebdcca49d7b
without including the pre kernel 3.4 support.
Signed-off-by: Mathias Kresin <dev@kresin.me>
Signed-off-by: Felix Fietkau <nbd@nbd.name> [minor cleanup]