From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 974D2EDEC69 for ; Wed, 13 Sep 2023 14:38:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1694615905; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=9uJyuH+jZ7mZWANAY7akr3pqgzGdW0iuo9oDpjwiLOs=; b=hgI44HDOEWcHDyrfB50ZuknwZP2zlAnMqS+qEw/fbJUiahe4g27/W+FLnTq03AC2x9GYn+ 33x3JZtv5MRFYKiHjdlKywBs+2TWe3lb9xvK2Gg/XhOEeym5OmklAItnVRr+W3hOocLP7T 6iWMjsjE7wqcfhoHaKshq0fAiMxKEnw= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-464-vPUDAgf4OkKbkherAGqMHg-1; Wed, 13 Sep 2023 10:38:23 -0400 X-MC-Unique: vPUDAgf4OkKbkherAGqMHg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 9A3AE88B7AD; Wed, 13 Sep 2023 14:38:20 +0000 (UTC) Received: from mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com [10.30.29.100]) by smtp.corp.redhat.com (Postfix) with ESMTP id 32EC640C6EA8; Wed, 13 Sep 2023 14:38:20 +0000 (UTC) Received: from mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (localhost [IPv6:::1]) by mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (Postfix) with ESMTP id E5A7019465B5; Wed, 13 Sep 2023 14:38:19 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) by mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (Postfix) with ESMTP id D640919465B1 for ; Wed, 13 Sep 2023 14:38:18 +0000 (UTC) Received: by smtp.corp.redhat.com (Postfix) id BEF9863A52; Wed, 13 Sep 2023 14:38:18 +0000 (UTC) Received: from octiron.msp.redhat.com (octiron.msp.redhat.com [10.15.80.209]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A3CD42904; Wed, 13 Sep 2023 14:38:18 +0000 (UTC) Received: from octiron.msp.redhat.com (localhost.localdomain [127.0.0.1]) by octiron.msp.redhat.com (8.14.9/8.14.9) with ESMTP id 38DEcAR7002576; Wed, 13 Sep 2023 09:38:10 -0500 Received: (from bmarzins@localhost) by octiron.msp.redhat.com (8.14.9/8.14.9/Submit) id 38DEc9M3002575; Wed, 13 Sep 2023 09:38:09 -0500 Date: Wed, 13 Sep 2023 09:38:09 -0500 From: Benjamin Marzinski To: Martin Wilck Message-ID: <20230913143809.GW7412@octiron.msp.redhat.com> References: <20230911163846.27197-1-mwilck@suse.com> <20230911163846.27197-23-mwilck@suse.com> <20230912230048.GR7412@octiron.msp.redhat.com> <592dd1bd954e2ccc33e1e0d837421d649fdafdf7.camel@suse.com> MIME-Version: 1.0 In-Reply-To: <592dd1bd954e2ccc33e1e0d837421d649fdafdf7.camel@suse.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Subject: Re: [dm-devel] [PATCH v2 22/37] libmultipath: sort aliases by length and strcmp X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: dm-devel@redhat.com Errors-To: dm-devel-bounces@redhat.com Sender: "dm-devel" X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable On Wed, Sep 13, 2023 at 03:53:25PM +0200, Martin Wilck wrote: > On Tue, 2023-09-12 at 18:00 -0500, Benjamin Marzinski wrote: > > On Mon, Sep 11, 2023 at 06:38:31PM +0200, mwilck@suse.com=A0wrote: > > > From: Martin Wilck > > >=20 > > > The current sort order of aliases is alphabetical, which is does > > > not match > > > the actual order of aliases, where "mpathaa" > "mpathz". Change the > > > ordering as > > > follows: first sort by string length, then alphabetically. This > > > will make > > > sure that for aliases with the same prefix, alias order is correct > > > ("mpathaaa" > > > will be sorted after "mpathzz", etc). Even for mixed prefixes, the > > > alias > > > order will be correct for every individual prefix, even though > > > aliases with > > > different prefixes may alternate in the file. > > >=20 > > > Signed-off-by: Martin Wilck > > > --- > > > =A0libmultipath/alias.c | 45 +++++++++++++++++++++++++++++++++------- > > > ---- > > > =A01 file changed, 34 insertions(+), 11 deletions(-) > > >=20 > > > diff --git a/libmultipath/alias.c b/libmultipath/alias.c > > > index 58436ec..af6565b 100644 > > > --- a/libmultipath/alias.c > > > +++ b/libmultipath/alias.c > > > @@ -117,6 +117,35 @@ static const struct binding > > > *get_binding_for_wwid(const Bindings *bindings, > > > =A0=A0=A0=A0=A0=A0=A0=A0return NULL; > > > =A0} > > > =A0 > > > +/* > > > + * Sort order for aliases. > > > + * > > > + * The "numeric" ordering of aliases for a given prefix P is > > > + * Pa, ..., Pz, Paa, ..., Paz, Pba, ... , Pzz, Paaa, ..., Pzzz, > > > Paaaa, ... > > > + * We use the fact that for equal prefix, longer strings are > > > always > > > + * higher than shorter ones. Strings of equal length are sorted > > > alphabetically. > > > + * This is achieved by sorting be length first, then using > > > strcmp(). > > > + * If multiple prefixes are in use, the aliases with a given > > > prefix will > > > + * not necessarily be in a contiguous range of the vector, but > > > they will > > > + * be ordered such that for a given prefix, numercally higher > > > aliases will > > > + * always be sorted after lower ones. > > > + */ > > > +static int alias_compar(const void *p1, const void *p2) > > > +{ > >=20 > > I'm confused as to why we need to pass p1 and p2 and pointers to > > pointers to chars, instead of simply as pointers to chars. We always > > derefence them immediately, and only use the dereferenced pointers. > > Am I > > missing something? >=20 > I wanted to make the relationship of alias_compar() and > mp_alias_compar() as obvious as possible. mp_alias_compar() takes=20 > (struct mpentry **) arguments, because it's used as an argument to > vector_sort() aka msort(), which has the same calling convention as > qsort()'s "compar" argument. Therefore I wrote alias_compar() such that > it takes (char **) pointers. This way we could use alias_compar() as an > argument to vector_sort() as well, even though we currently don't. >=20 >=20 > Does this make sense? If not, I can change it, but I think the function > should not be named alias_compar() if it can't be passed to > vector_sort(). It's fine as it is. I was just confused as to why. -Ben >=20 > Martin -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel