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

[Daniel Wagner]

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.