From nobody Mon Feb 9 11:47:49 2026 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8BBAA22538F for ; Sun, 21 Dec 2025 02:53:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766285590; cv=none; b=unfWL4vmxV+0C66xG4HHpHhJOiaAIn9J9/73VFjnRhFcyzt0XXfIRL0tm/kuii+b2W0OUCrVn0xMgL8aGyCqoAY7d6EwMQOehyrJQ1NjxocMBTTfGOIulNVxE/JY0nVIlSUPc7+5Pnn1bV5F6AWOt2oTW6AisSSAx9ROVqDmwjg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766285590; c=relaxed/simple; bh=G5zNazOwnANuZl6Zkj9RKTqDaNGEAQbBly+9bJs0YTI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Fb2s28jJo9Q/2AnUpc47u0+JOrDSn/YDsc2kqKWWcOMbaMdxOUpBIz3PZ8jEDdpcqsX8DmbrIEKdZjYZqKK9RxJJ6CehPenyn+GxKSNApAR49qB3BKsUFBUew+9UdzzlAMIpzaFeU86urmlPTncnvrIjelebCUYfdeI8ZK7XYME= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=W8i0IyEt; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="W8i0IyEt" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1766285587; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ot0Li/Rd6I4GT/jTlGyYgi3ywYy+1RwNsdBzqtFhH9I=; b=W8i0IyEttFxuXOeWM1u4yyBBWc+1NouYLl1Ja+/5eDkX1c3sVkFiNZgC3egefpq8kXFW9k IC3/yQwx2DJ9uZRT2oG3cKSY+A1WYT1Ib14bMboHgK+3eaG239afPBi2U90S/DJVT2B3qX chN7FTFkOSik0exhriGSo0dBFG+v8TM= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-41-nzwPdJNfNdKtPdmRKsmofQ-1; Sat, 20 Dec 2025 21:53:03 -0500 X-MC-Unique: nzwPdJNfNdKtPdmRKsmofQ-1 X-Mimecast-MFC-AGG-ID: nzwPdJNfNdKtPdmRKsmofQ_1766285581 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id AAC7E1956088; Sun, 21 Dec 2025 02:53:01 +0000 (UTC) Received: from pasta.fast.eng.rdu2.dc.redhat.com (unknown [10.44.32.8]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 626A9180049F; Sun, 21 Dec 2025 02:52:58 +0000 (UTC) From: Andreas Gruenbacher To: Christoph Hellwig , Jens Axboe , Chris Mason , David Sterba , Satya Tangirala Cc: Andreas Gruenbacher , linux-block@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-raid@vger.kernel.org, dm-devel@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [RFC v2 06/17] bio: do not check bio->bi_status before assigning to it Date: Sun, 21 Dec 2025 03:52:21 +0100 Message-ID: <20251221025233.87087-7-agruenba@redhat.com> In-Reply-To: <20251221025233.87087-1-agruenba@redhat.com> References: <20251221025233.87087-1-agruenba@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Content-Type: text/plain; charset="utf-8" In a few places, we check if to->bi_status is 0 before setting it. This creates the impression of preserving the first error code that occurs, but that is not actually the case because bio->bi_status is not updated atomically. (And even updating bio->bi_status atomically wouldn't preserve the first error in bio chains longer than two.) We don't actually need to preserve the first error code, though; and all that matters is that when an error occurs, one of the error codes is preserved. Checking bio->bi_status before assigning to it might also have been meant as an optimization. We are on an error path and the potential benefit is miniscule, though. So, don't check bio->bi_status before assigning to it. Created with Coccinelle using the following semantic patch: @@ expression status; struct bio *bio; @@ - if (status && !bio->bi_status) - bio->bi_status =3D status; + bio_set_status(bio, status); @@ expression status; struct bio *bio; @@ - if (status !=3D BLK_STS_OK && bio->bi_status =3D=3D BLK_STS_OK) - bio->bi_status =3D status; + bio_set_status(bio, status); @@ expression status; struct bio *bio; @@ - if (unlikely(status) && !bio->bi_status) - bio->bi_status =3D status; + bio_set_status(bio, status); @@ expression status; struct bio bio; @@ - if (status && !bio.bi_status) - bio.bi_status =3D status; + bio_set_status(&bio, status); --- block/bio.c | 3 +-- block/fops.c | 3 +-- drivers/md/dm-integrity.c | 3 +-- drivers/md/dm-zoned-target.c | 3 +-- drivers/md/md.c | 6 ++---- 5 files changed, 6 insertions(+), 12 deletions(-) diff --git a/block/bio.c b/block/bio.c index 3f408e1ba13f..5389321872f0 100644 --- a/block/bio.c +++ b/block/bio.c @@ -314,8 +314,7 @@ static struct bio *__bio_chain_endio(struct bio *bio) { struct bio *parent =3D bio->bi_private; =20 - if (bio->bi_status && !parent->bi_status) - parent->bi_status =3D bio->bi_status; + bio_set_status(parent, bio->bi_status); bio_put(bio); return parent; } diff --git a/block/fops.c b/block/fops.c index b4f911273289..a4a6972cbfbf 100644 --- a/block/fops.c +++ b/block/fops.c @@ -135,8 +135,7 @@ static void blkdev_bio_end_io(struct bio *bio) bool should_dirty =3D dio->flags & DIO_SHOULD_DIRTY; bool is_sync =3D dio->flags & DIO_IS_SYNC; =20 - if (bio->bi_status && !dio->bio.bi_status) - dio->bio.bi_status =3D bio->bi_status; + bio_set_status(&dio->bio, bio->bi_status); =20 if (bio_integrity(bio)) bio_integrity_unmap_user(bio); diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c index e380ed7b2a7b..6d04b067060d 100644 --- a/drivers/md/dm-integrity.c +++ b/drivers/md/dm-integrity.c @@ -1616,8 +1616,7 @@ static void dec_in_flight(struct dm_integrity_io *dio) schedule_autocommit(ic); =20 bio =3D dm_bio_from_per_bio_data(dio, sizeof(struct dm_integrity_io)); - if (unlikely(dio->bi_status) && !bio->bi_status) - bio->bi_status =3D dio->bi_status; + bio_set_status(bio, dio->bi_status); if (likely(!bio->bi_status) && unlikely(bio_sectors(bio) !=3D dio->range= .n_sectors)) { dio->range.logical_sector +=3D dio->range.n_sectors; bio_advance(bio, dio->range.n_sectors << SECTOR_SHIFT); diff --git a/drivers/md/dm-zoned-target.c b/drivers/md/dm-zoned-target.c index 9da329078ea4..efb960eca8ea 100644 --- a/drivers/md/dm-zoned-target.c +++ b/drivers/md/dm-zoned-target.c @@ -77,8 +77,7 @@ static inline void dmz_bio_endio(struct bio *bio, blk_sta= tus_t status) struct dmz_bioctx *bioctx =3D dm_per_bio_data(bio, sizeof(struct dmz_bioctx)); =20 - if (status !=3D BLK_STS_OK && bio->bi_status =3D=3D BLK_STS_OK) - bio->bi_status =3D status; + bio_set_status(bio, status); if (bioctx->dev && bio->bi_status !=3D BLK_STS_OK) bioctx->dev->flags |=3D DMZ_CHECK_BDEV; =20 diff --git a/drivers/md/md.c b/drivers/md/md.c index cbca792fa380..5afc6d63aa7b 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -9084,8 +9084,7 @@ static void md_end_clone_io(struct bio *bio) if (bio_data_dir(orig_bio) =3D=3D WRITE && md_bitmap_enabled(mddev, false= )) md_bitmap_end(mddev, md_io_clone); =20 - if (bio->bi_status && !orig_bio->bi_status) - orig_bio->bi_status =3D bio->bi_status; + bio_set_status(orig_bio, bio->bi_status); =20 if (md_io_clone->start_time) bio_end_io_acct(orig_bio, md_io_clone->start_time); @@ -9136,8 +9135,7 @@ void md_free_cloned_bio(struct bio *bio) if (bio_data_dir(orig_bio) =3D=3D WRITE && md_bitmap_enabled(mddev, false= )) md_bitmap_end(mddev, md_io_clone); =20 - if (bio->bi_status && !orig_bio->bi_status) - orig_bio->bi_status =3D bio->bi_status; + bio_set_status(orig_bio, bio->bi_status); =20 if (md_io_clone->start_time) bio_end_io_acct(orig_bio, md_io_clone->start_time); --=20 2.52.0