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 X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A6090C43382 for ; Thu, 27 Sep 2018 16:18:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 44EA721582 for ; Thu, 27 Sep 2018 16:18:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 44EA721582 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=net-space.pl Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-btrfs-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727603AbeI0Whu (ORCPT ); Thu, 27 Sep 2018 18:37:50 -0400 Received: from dibed.net-space.pl ([84.10.22.86]:56598 "EHLO dibed.net-space.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727282AbeI0Whu (ORCPT ); Thu, 27 Sep 2018 18:37:50 -0400 Received: (from localhost user: 'dkiper' uid#4000 fake: STDIN (dkiper@dibed.net-space.pl)) by router-fw-old.i.net-space.pl id S1871587AbeI0QSh (ORCPT ); Thu, 27 Sep 2018 18:18:37 +0200 Date: Thu, 27 Sep 2018 18:18:37 +0200 From: Daniel Kiper To: kreijack@inwind.it Cc: Daniel Kiper , grub-devel@gnu.org, linux-btrfs@vger.kernel.org Subject: Re: [PATCH 7/9] btrfs: Add support for recovery for a RAID 5 btrfs profiles. Message-ID: <20180927161837.GC22053@router-fw-old.i.net-space.pl> References: <20180919184040.22540-1-kreijack@libero.it> <20180919184040.22540-8-kreijack@libero.it> <20180925191032.GD30715@router-fw-old.i.net-space.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.3.28i Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Wed, Sep 26, 2018 at 09:55:57PM +0200, Goffredo Baroncelli wrote: > On 25/09/2018 21.10, Daniel Kiper wrote: > > On Wed, Sep 19, 2018 at 08:40:38PM +0200, Goffredo Baroncelli wrote: > >> From: Goffredo Baroncelli > >> > >> Add support for recovery for a RAID 5 btrfs profile. In addition > >> it is added some code as preparatory work for RAID 6 recovery code. > >> > >> Signed-off-by: Goffredo Baroncelli > >> --- > >> grub-core/fs/btrfs.c | 169 +++++++++++++++++++++++++++++++++++++++++-- > >> 1 file changed, 164 insertions(+), 5 deletions(-) > >> > >> diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c > >> index 5c1ebae77..55a7eeffc 100644 > >> --- a/grub-core/fs/btrfs.c > >> +++ b/grub-core/fs/btrfs.c > >> @@ -29,6 +29,7 @@ > >> #include > >> #include > >> #include > >> +#include > >> > >> GRUB_MOD_LICENSE ("GPLv3+"); > >> > >> @@ -665,6 +666,148 @@ btrfs_read_from_chunk (struct grub_btrfs_data *data, > >> return err; > >> } > >> > >> +struct raid56_buffer { > >> + void *buf; > >> + int data_is_valid; > >> +}; > >> + > >> +static void > >> +rebuild_raid5 (char *dest, struct raid56_buffer *buffers, > >> + grub_uint64_t nstripes, grub_uint64_t csize) > >> +{ > >> + grub_uint64_t i; > >> + int first; > >> + > >> + i = 0; > >> + while (buffers[i].data_is_valid && i < nstripes) > >> + ++i; > > > > for (i = 0; buffers[i].data_is_valid && i < nstripes; i++); > > > >> + if (i == nstripes) > >> + { > >> + grub_dprintf ("btrfs", "called rebuild_raid5(), but all disks are OK\n"); > >> + return; > >> + } > >> + > >> + grub_dprintf ("btrfs", "rebuilding RAID 5 stripe #%" PRIuGRUB_UINT64_T "\n", > >> + i); > > > > One line here please. > > > >> + for (i = 0, first = 1; i < nstripes; i++) > >> + { > >> + if (!buffers[i].data_is_valid) > >> + continue; > >> + > >> + if (first) { > >> + grub_memcpy(dest, buffers[i].buf, csize); > >> + first = 0; > >> + } else > >> + grub_crypto_xor (dest, dest, buffers[i].buf, csize); > >> + > >> + } > > > > Hmmm... I think that this function can be simpler. You can drop first > > while/for and "if (i == nstripes)". Then here: > > > > if (first) { > > grub_dprintf ("btrfs", "called rebuild_raid5(), but all disks are OK\n"); > > > > Am I right? > > Ehm.. no. The "if" is an internal check to avoid BUG. rebuild_raid5() should be called only if some disk is missed. > To perform this control, the code checks if all buffers are valid. Otherwise there is an internal BUG. Something is wrong here. I think that the code checks if it is an invalid buffer. If there is not then GRUB complains. Right? However, it looks that I misread the code and made a mistake here. So, please ignore this change. Though please change while() with for() at the beginning. Daniel