From: NeilBrown <neilb@xxxxxxxx> Subject: autofs: clear O_NONBLOCK on the pipe 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. Link: http://lkml.kernel.org/r/154993550902.3321.1183632970046073478.stgit@pluto-themaw-net Signed-off-by: NeilBrown <neilb@xxxxxxxx> Signed-off-by: Ian Kent <raven@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- --- a/fs/autofs/autofs_i.h~autofs-clear-o_nonblock-on-the-pipe +++ a/fs/autofs/autofs_i.h @@ -216,6 +216,8 @@ static inline int autofs_prepare_pipe(st return -EINVAL; /* We want a packet pipe */ pipe->f_flags |= O_DIRECT; + /* We don't expect -EAGAIN */ + pipe->f_flags &= ~O_NONBLOCK; return 0; } _
