[PATCH blktests v2 02/18] nvme/rc: silence fcloop cleanup failures

[Shinichiro Kawasaki]

On Mar 25, 2024 / 19:27, Daniel Wagner wrote:
> On Fri, Mar 22, 2024 at 02:49:59PM +0100, Daniel Wagner wrote:
> > When the ctl file is missing we are logging
> > 
> >   tests/nvme/rc: line 265: /sys/class/fcloop/ctl/del_target_port: No such file or directory
> >   tests/nvme/rc: line 257: /sys/class/fcloop/ctl/del_local_port: No such file or directory
> >   tests/nvme/rc: line 249: /sys/class/fcloop/ctl/del_remote_port: No such file or directory
> > 
> > because the first redirect operator fails. Also it's not possible to
> > redirect the 'echo' error to /dev/null, because it's a builtin command
> > which escapes the stderr redirect operator (why?).
> > 
> > Anyway, the simplest way to catch this error is to first check if the
> > control file exists before attempting to write to it.
> > 
> > Signed-off-by: Daniel Wagner <dwagner at suse.de>
> > ---
> >  tests/nvme/rc | 15 ++++++++++++---
> >  1 file changed, 12 insertions(+), 3 deletions(-)
> > 
> > diff --git a/tests/nvme/rc b/tests/nvme/rc
> > index 78d84af72e73..865c8c351159 100644
> > --- a/tests/nvme/rc
> > +++ b/tests/nvme/rc
> > @@ -234,7 +234,10 @@ _nvme_fcloop_del_rport() {
> >  	local remote_wwpn="$4"
> >  	local loopctl=/sys/class/fcloop/ctl
> >  
> > -	echo "wwnn=${remote_wwnn},wwpn=${remote_wwpn}" > ${loopctl}/del_remote_port 2> /dev/null
> > +	if [[ ! -f "${loopctl}/del_remote_port" ]]; then
> > +		return
> > +	fi
> > +	echo "wwnn=${remote_wwnn},wwpn=${remote_wwpn}" > "${loopctl}/del_remote_port"
> 
> BTW, I was told why the redirect doesn't work. The reason is that the
> 'No such file or directly' is issued by the shell and not 'echo' because
> 'echo' is a builtin command. Thus the right way to catch is to do
> 
>   (echo "foo" > file) 2>/dev/null
>   {echo "foo" > file} 2>/dev/null
> 
> I suppose we want to keep it simple and just add the brackets around the echos.

Both has pros and cons: added brackets are simpler, while file existence check
is more readable, IMO. I think either way is fine.