From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vk1-f194.google.com ([209.85.221.194]:43717 "EHLO mail-vk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730271AbeKFVR1 (ORCPT ); Tue, 6 Nov 2018 16:17:27 -0500 Received: by mail-vk1-f194.google.com with SMTP id o130so317734vke.10 for ; Tue, 06 Nov 2018 03:52:36 -0800 (PST) MIME-Version: 1.0 References: <20181105122610.1555-1-hans.ml.holmberg@owltronix.com> <20181105122610.1555-2-hans.ml.holmberg@owltronix.com> In-Reply-To: From: Hans Holmberg Date: Tue, 6 Nov 2018 12:52:25 +0100 Message-ID: Subject: Re: [PATCH v2 1/7] lightnvm: pblk: fix resubmission of overwritten write err lbas To: sboisvert@gydle.com Cc: Matias Bjorling , Javier Gonzalez , linux-block@vger.kernel.org, Linux Kernel Mailing List , Hans Holmberg Content-Type: text/plain; charset="UTF-8" Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org On Mon, Nov 5, 2018 at 4:12 PM Sebastien Boisvert wrote: > > > > On 2018-11-05 7:26 a.m., Hans Holmberg wrote: > > From: Hans Holmberg > > > > Make sure we only look up valid lba addresses on the resubmission path. > > > > If an lba is invalidated in the write buffer, that sector will be > > submitted to disk(as it is already mapped to a ppa), and that write > > submitted to disk(as it is already mapped to a ppa), and that write > ^ > add a space > > > might fail, resulting in a crash when trying to look up the lba in the > > mapping table (as the lba is marked as invalid). > > > > Signed-off-by: Hans Holmberg > > --- > > drivers/lightnvm/pblk-write.c | 8 +++++--- > > 1 file changed, 5 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/lightnvm/pblk-write.c b/drivers/lightnvm/pblk-write.c > > index fa8726493b39..3ddd16f47106 100644 > > --- a/drivers/lightnvm/pblk-write.c > > +++ b/drivers/lightnvm/pblk-write.c > > @@ -148,9 +148,11 @@ static void pblk_prepare_resubmit(struct pblk *pblk, unsigned int sentry, > > w_ctx = &entry->w_ctx; > > > > /* Check if the lba has been overwritten */ > > - ppa_l2p = pblk_trans_map_get(pblk, w_ctx->lba); > > - if (!pblk_ppa_comp(ppa_l2p, entry->cacheline)) > > - w_ctx->lba = ADDR_EMPTY; > > + if (w_ctx->lba != ADDR_EMPTY) { > > + ppa_l2p = pblk_trans_map_get(pblk, w_ctx->lba); > > + if (!pblk_ppa_comp(ppa_l2p, entry->cacheline)) > > + w_ctx->lba = ADDR_EMPTY; > > + } > > Was w_ctx->lba set to ADDR_EMPTY in the same kernel I/O thread ? > > I wonder if w_ctx->lba could become ADDR_EMPTY after > > if (w_ctx->lba != ADDR_EMPTY) { > > but before > > ppa_l2p = pblk_trans_map_get(pblk, w_ctx->lba); It can't, the lba adress can only be changed on the write error handling path, and we'll have to resubmit the write before that can happen. Thanks for the review. / Hans > > > > > > /* Mark up the entry as submittable again */ > > flags = READ_ONCE(w_ctx->flags); > >