From patchwork Fri May 27 05:58:06 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 12863024 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E13ABC433F5 for ; Fri, 27 May 2022 05:58:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243017AbiE0F6O (ORCPT ); Fri, 27 May 2022 01:58:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35552 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235470AbiE0F6L (ORCPT ); Fri, 27 May 2022 01:58:11 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 026DE3A18F for ; Thu, 26 May 2022 22:58:10 -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:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type: Content-ID:Content-Description:In-Reply-To:References; bh=kvkxB51uUiZEsmCSNcfGEI81a4XYEz0zdOH+fH5VPQU=; b=r4kiAEAAcMZHplf8pn29rb92hO kqO7sOnFdXnPy8NL0Gsibz2358aVGB+8iLBMD2FhleNfMRokZeaHSalFpqTfZV3W2Vl+6qjdiXe49 LvPqQEEo8sCvAKd/Chlei6sO95ZKCDprVpaYJhOExmB+rBjifmWdRLPyb069Ee4E7OVjMebMEtraK d4X5cHNLuN50UTUlck2BQYqlZ8WvcteU515puMX9l3G1plvIMvuRrIC3OfkupZPuGuDpn87o0cpoR oOU4VARgkwV1m0Z0Rr+euPun81oDXYQhxaDZYxzQEPldl4oafBeMAIRAefa2Lc/nTcaWrAiUO6gq3 AeTokPDA==; Received: from [2001:4bb8:18c:7298:b5ab:7d49:c6be:2011] (helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1nuSzA-00GifB-HU; Fri, 27 May 2022 05:58:08 +0000 From: Christoph Hellwig To: axboe@kernel.dk Cc: linux-block@vger.kernel.org, Ming Lei Subject: [PATCH] block, loop: support partitions without scanning Date: Fri, 27 May 2022 07:58:06 +0200 Message-Id: <20220527055806.1972352-1-hch@lst.de> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Historically we did distinguish between a flag that surpressed partition scanning, and a combinations of the minors variable and another flag if any partitions were supported. This was generally confusing and doesn't make much sense, but some corner case uses of the loop driver actually do want to support manually added partitions on a device that does not actively scan for partitions. To make things worsee the loop driver also wants to dynamically toggle the scanning for partitions on a live gendisk, which makes the disk->flags updates non-atomic. Introduce a new GD_SUPPRESS_PART_SCAN bit in disk->state that disables just scanning for partitions, and toggle that instead of GENHD_FL_NO_PART in the loop driver. Fixes: 1ebe2e5f9d68 ("block: remove GENHD_FL_EXT_DEVT") Reported-by: Ming Lei Signed-off-by: Christoph Hellwig Reviewed-by: Ming Lei --- block/genhd.c | 2 ++ drivers/block/loop.c | 8 ++++---- include/linux/blkdev.h | 1 + 3 files changed, 7 insertions(+), 4 deletions(-) diff --git a/block/genhd.c b/block/genhd.c index 36532b9318419..27205ae47d593 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -385,6 +385,8 @@ int disk_scan_partitions(struct gendisk *disk, fmode_t mode) if (disk->flags & (GENHD_FL_NO_PART | GENHD_FL_HIDDEN)) return -EINVAL; + if (test_bit(GD_SUPPRESS_PART_SCAN, &disk->state)) + return -EINVAL; if (disk->open_partitions) return -EBUSY; diff --git a/drivers/block/loop.c b/drivers/block/loop.c index e2cb51810e89a..5bef97ffbe21e 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1102,7 +1102,7 @@ static int loop_configure(struct loop_device *lo, fmode_t mode, lo->lo_flags |= LO_FLAGS_PARTSCAN; partscan = lo->lo_flags & LO_FLAGS_PARTSCAN; if (partscan) - lo->lo_disk->flags &= ~GENHD_FL_NO_PART; + clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state); loop_global_unlock(lo, is_loop); if (partscan) @@ -1198,7 +1198,7 @@ static void __loop_clr_fd(struct loop_device *lo, bool release) */ lo->lo_flags = 0; if (!part_shift) - lo->lo_disk->flags |= GENHD_FL_NO_PART; + set_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state); mutex_lock(&lo->lo_mutex); lo->lo_state = Lo_unbound; mutex_unlock(&lo->lo_mutex); @@ -1308,7 +1308,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) if (!err && (lo->lo_flags & LO_FLAGS_PARTSCAN) && !(prev_lo_flags & LO_FLAGS_PARTSCAN)) { - lo->lo_disk->flags &= ~GENHD_FL_NO_PART; + clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state); partscan = true; } out_unlock: @@ -2011,7 +2011,7 @@ static int loop_add(int i) * userspace tools. Parameters like this in general should be avoided. */ if (!part_shift) - disk->flags |= GENHD_FL_NO_PART; + set_bit(GD_SUPPRESS_PART_SCAN, &disk->state); mutex_init(&lo->lo_mutex); lo->lo_number = i; spin_lock_init(&lo->lo_lock); diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 1b24c1fb3bb1e..608d577734c29 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -147,6 +147,7 @@ struct gendisk { #define GD_DEAD 2 #define GD_NATIVE_CAPACITY 3 #define GD_ADDED 4 +#define GD_SUPPRESS_PART_SCAN 5 struct mutex open_mutex; /* open/close mutex */ unsigned open_partitions; /* number of open partitions */