[PATCH] ctdb-scripts: Fix tcp_tw_recycle existence check

[Martin Schwenke]

On Sun,  2 Jun 2019 23:44:15 -0300, Rafael David Tinoco via
samba-technical <samba-technical at lists.samba.org> wrote:

> net.ipv4.tcp_tw_recycle has been removed from Linux 4.12 but, still,
> makes sense to check its existence. Unfortunately, current check does
> not test for the procfs file existence. This commit fixes the issue.
> 
> Signed-off-by: Rafael David Tinoco <rafaeldtinoco at ubuntu.com>
> ---
>  ctdb/config/nfs-linux-kernel-callout | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/ctdb/config/nfs-linux-kernel-callout b/ctdb/config/nfs-linux-kernel-callout
> index def69a04649..71d8ecf8074 100755
> --- a/ctdb/config/nfs-linux-kernel-callout
> +++ b/ctdb/config/nfs-linux-kernel-callout
> @@ -281,8 +281,8 @@ nfs_startup ()
>      basic_stop "nfs" || true
>      basic_start "nfs"
>      _f="${PROCFS_PATH}/sys/net/ipv4/tcp_tw_recycle"
> -    if [ "$_f" ] ; then
> -	echo 1 >"$_f"
> +    if [ -f "$_f" ] ; then
> +	    echo 1 >"$_f"
>      fi
>  }

I actually prefer this version.  The script already guarantees that
PROCFS_PATH is set, so let's not complicate this fix with an
unnecessary check.

Now that I'm old, I also prefer the explicit if-statement in this
version, instead of the && pipeline in the later version.  The more
verbose if-statement is easier to read.  :-)

Reviewed-by: Martin Schwenke <martin at meltin.net>

Can the 2nd reviewer please add:

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13984

to the commit message before pushing?  We will backport this fix to
stable releases...

Thanks!

peace & happiness,
martin