On Mon, 2019-02-11 at 10:37 +1100, NeilBrown wrote: > autofs does not expect the pipe it is given > to have O_NONBLOCK set - specifically if __kernel_write() > in autofs_write() returns -EAGAIN, this is treated > as a fatal error and the pipe is closed. > > For safety autofs should, therefore, clear the O_NONBLOCK flag. > > Releases of systemd prior to 8th February 2019 used > pipe2(p, O_NONBLOCK|O_CLOEXEC) > and thus (inadvertently) set this flag.
Thanks Neil, this does look like an obvious problem. > > Signed-off-by: NeilBrown <ne...@suse.com> > --- > fs/autofs/autofs_i.h | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/fs/autofs/autofs_i.h b/fs/autofs/autofs_i.h > index 3e59f0ed777b..331192bed0d5 100644 > --- a/fs/autofs/autofs_i.h > +++ b/fs/autofs/autofs_i.h > @@ -215,6 +215,8 @@ static inline int autofs_prepare_pipe(struct file *pipe) > return -EINVAL; > /* We want a packet pipe */ > pipe->f_flags |= O_DIRECT; > + /* We don't expect -EAGAIN */ > + pipe->f_flags &= ~O_NONBLOCK; > return 0; > } >
