From patchwork Tue Oct 17 18:48:19 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 13425711 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 5CBA642BFF for ; Tue, 17 Oct 2023 18:48:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="SfCbzY8z" Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E53B92; Tue, 17 Oct 2023 11:48:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=3p4oO3bOXrhbykt9aeueJv3mlaSlSZVuqrgRI70Z3n8=; b=SfCbzY8znMcuOv5VNgHyY+biQY p6t02rycUvs0jSeqmIaPRyf8SaAeE1kyDbpncHpx47/XZogN88cEkUYcbKe9+dqxEAHVqVSNqibbU RrhyjhPgpBmYTFWO/h/Pm87q/nkj9jD66p3V3ZeUo8KG5lEDAnx61/NPfWAT2kQfrG/ILtJWv36Zf XvFD+SgML9ux/P3GQ0ksyNSxe5TBY5MVcSeKMnDVHmhoJ7iVn9yRBHPOwsU09k1DN1OeruWBDkgik JMZd8KtC+L8cfQiUknwiHVJE1OvzDddWM4tMyZweAIx5GYre2vVm0kRRaoUfKQPibnXhiM3P+z62v 2WrgfhNw==; Received: from 2a02-8389-2341-5b80-39d3-4735-9a3c-88d8.cable.dynamic.v6.surfer.at ([2a02:8389:2341:5b80:39d3:4735:9a3c:88d8] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1qsp7G-00D0Kj-24; Tue, 17 Oct 2023 18:48:30 +0000 From: Christoph Hellwig To: Christian Brauner , Al Viro , Jens Axboe Cc: Jan Kara , Denis Efremov , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH 1/5] block: simplify bdev_del_partition() Date: Tue, 17 Oct 2023 20:48:19 +0200 Message-Id: <20231017184823.1383356-2-hch@lst.de> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20231017184823.1383356-1-hch@lst.de> References: <20231017184823.1383356-1-hch@lst.de> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Spam-Status: No, score=-1.7 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_EF,HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_NONE autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net From: Christian Brauner BLKPG_DEL_PARTITION refuses to delete partitions that still have openers, i.e., that has an elevated @bdev->bd_openers count. If a device is claimed by setting @bdev->bd_holder and @bdev->bd_holder_ops @bdev->bd_openers and @bdev->bd_holders are incremented. @bdev->bd_openers is effectively guaranteed to be >= @bdev->bd_holders. So as long as @bdev->bd_openers isn't zero we know that this partition is still in active use and that there might still be @bdev->bd_holder and @bdev->bd_holder_ops set. The only current example is @fs_holder_ops for filesystems. But that means bdev_mark_dead() which calls into bdev->bd_holder_ops->mark_dead::fs_bdev_mark_dead() is a nop. As long as there's an elevated @bdev->bd_openers count we can't delete the partition and if there isn't an elevated @bdev->bd_openers count then there's no @bdev->bd_holder or @bdev->bd_holder_ops. So simply open-code what we need to do. This gets rid of one more instance where we acquire s_umount under @disk->open_mutex. Link: https://lore.kernel.org/r/20231016-fototermin-umriss-59f1ea6c1fe6@brauner Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Reviewed-by: Jens Axboe Signed-off-by: Christian Brauner Signed-off-by: Christoph Hellwig Reviewed-by: Ming Lei --- block/partitions/core.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/block/partitions/core.c b/block/partitions/core.c index e137a87f4db0d3..b0585536b407a5 100644 --- a/block/partitions/core.c +++ b/block/partitions/core.c @@ -485,7 +485,18 @@ int bdev_del_partition(struct gendisk *disk, int partno) if (atomic_read(&part->bd_openers)) goto out_unlock; - delete_partition(part); + /* + * We verified that @part->bd_openers is zero above and so + * @part->bd_holder{_ops} can't be set. And since we hold + * @disk->open_mutex the device can't be claimed by anyone. + * + * So no need to call @part->bd_holder_ops->mark_dead() here. + * Just delete the partition and invalidate it. + */ + + remove_inode_hash(part->bd_inode); + invalidate_bdev(part); + drop_partition(part); ret = 0; out_unlock: mutex_unlock(&disk->open_mutex);