From patchwork Sun Mar 12 19:10:31 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Alyssa Ross X-Patchwork-Id: 13171774 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 58991C6FA99 for ; Sun, 12 Mar 2023 19:11:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229829AbjCLTLB (ORCPT ); Sun, 12 Mar 2023 15:11:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58794 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229925AbjCLTK7 (ORCPT ); Sun, 12 Mar 2023 15:10:59 -0400 Received: from wout2-smtp.messagingengine.com (wout2-smtp.messagingengine.com [64.147.123.25]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0BBB5303DB; Sun, 12 Mar 2023 12:10:49 -0700 (PDT) Received: from compute1.internal (compute1.nyi.internal [10.202.2.41]) by mailout.west.internal (Postfix) with ESMTP id 9E524320046E; Sun, 12 Mar 2023 15:10:47 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute1.internal (MEProxy); Sun, 12 Mar 2023 15:10:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alyssa.is; h=cc :cc:content-transfer-encoding:content-type:content-type:date :date:from:from:in-reply-to:message-id:mime-version:reply-to :sender:subject:subject:to:to; s=fm1; t=1678648247; x= 1678734647; bh=Cvh4ZiacG5VE6kcR8Gk7s5+fYYDWMIvbwr/3VYeaQZ4=; b=k X+AnLqLq4MLdXHy+t+2is0PlLlD7ud3YWETgaLWAP5nQ5kVuhBCdwSpTx/S62NbI 7+HRx3jRkN8Y9B20bCvyDPtTtw90qRFZN/yYrGoOqmHJAFBf/vH98xKQ67lmAw/u KjxdDaVXs/16cCRKyOo2k2YsI8uaS7OIHVHl07X+RFw5ioITxeDzYHDI1qPpC3OX y+s/fD+64p6BgPXxh8an5lGc1fxOQnah4SCsxpkZ1qR9o/NYnBsN6eMnXFPQmZWv 1fE9DzScWIgzbgLGEzid6asztQno2ltg5GchMSRfbOR1tDKe+1if8zHxsC1WMBZg 0KFocWKYPbS3ghXDRGTHA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding :content-type:content-type:date:date:feedback-id:feedback-id :from:from:in-reply-to:message-id:mime-version:reply-to:sender :subject:subject:to:to:x-me-proxy:x-me-proxy:x-me-sender :x-me-sender:x-sasl-enc; s=fm2; t=1678648247; x=1678734647; bh=C vh4ZiacG5VE6kcR8Gk7s5+fYYDWMIvbwr/3VYeaQZ4=; b=vRA11/tAGCHarmsIR s2nKwyc0GCeCAKvbfF/ZhBJjEU9Ip+gCnurM6Q6qsHCjpfzv4P3zgeNGgrymWjP3 zdZhqeAQ74Nw7uYu/YDthOvq5OU4T7MZnOo6aqLgXNQbxGWX6RWQcoyR9Ph+dZ55 ikt7jS71lk2v99aigtZJPV5SBDKrM7USbnWnd/30jyiAOiqDoGMuPErUiANvXYWg z4Yhn5qlMQsqxSb1pFpivhpZrpSdptpfTINywVNShyBf/uf72k+8T49MyBPVNmlJ vO/2m892Am6rNSeqbV/5f5uNLXAbSoitMz88bjl870TnV0M1WHokeBraj1EnO8ep FFl2g== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvhedrvddvvddguddvtdcutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfgh necuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd enucfjughrpefhvfevufffkffogggtgfesthekredtredtjeenucfhrhhomheptehlhihs shgrucftohhsshcuoehhihesrghlhihsshgrrdhisheqnecuggftrfgrthhtvghrnhepve evgfehledtieelffegvdegveeukeevhfdtteeggeejvdduveegvefftefgueffnecuffho mhgrihhnpehkvghrnhgvlhdrohhrghenucevlhhushhtvghrufhiiigvpedtnecurfgrrh grmhepmhgrihhlfhhrohhmpehhihesrghlhihsshgrrdhish X-ME-Proxy: Feedback-ID: i12284293:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Sun, 12 Mar 2023 15:10:46 -0400 (EDT) Received: by x220.qyliss.net (Postfix, from userid 1000) id 3B3C423881; Sun, 12 Mar 2023 19:10:39 +0000 (UTC) From: Alyssa Ross To: Jens Axboe Cc: linux-kernel@vger.kernel.org, Alyssa Ross , Martijn Coenen , linux-block@vger.kernel.org Subject: [PATCH v2] loop: LOOP_CONFIGURE: send uevents for partitions Date: Sun, 12 Mar 2023 19:10:31 +0000 Message-Id: <20230312191031.551204-1-hi@alyssa.is> X-Mailer: git-send-email 2.37.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org LOOP_CONFIGURE is, as far as I understand it, supposed to be a way to combine LOOP_SET_FD and LOOP_SET_STATUS64 into a single syscall. When using LOOP_SET_FD+LOOP_SET_STATUS64, a single uevent would be sent for each partition found on the loop device after the second ioctl(), but when using LOOP_CONFIGURE, no such uevent was being sent. In the old setup, uevents are disabled for LOOP_SET_FD, but not for LOOP_SET_STATUS64. This makes sense, as it prevents uevents being sent for a partially configured device during LOOP_SET_FD — they're only sent at the end of LOOP_SET_STATUS64. But for LOOP_CONFIGURE, uevents were disabled for the entire operation, so that final notification was never issued. To fix this, I've moved the loop_reread_partitions() call, which causes the uevents to be issued, to after uevents are re-enabled, matching the behaviour of the LOOP_SET_FD+LOOP_SET_STATUS64 combination. I noticed this because Busybox's losetup program recently changed from using LOOP_SET_FD+LOOP_SET_STATUS64 to LOOP_CONFIGURE, and this broke my setup, for which I want a notification from the kernel any time a new partition becomes available. Signed-off-by: Alyssa Ross Fixes: 3448914e8cc5 ("loop: Add LOOP_CONFIGURE ioctl") Tested-by: Alyssa Ross Signed-off-by: Alyssa Ross Signed-off-by: Christoph Hellwig --- v1: https://lore.kernel.org/linux-block/20230221222847.607096-1-hi@alyssa.is/ v1 was an RFC, because I was looking for advice on how to handle distinguishing between LOOP_SET_FD with non-zero max_part (in which case partscan will be true, but a uevent should not be emitted), and LOOP_CONFIGURE (where a uevent should be emitted). I didn't hear anything, but I did some experimentation of my own, and adding a partscan_uevent parameter to distinguish between LOOP_SET_FD and LOOP_CONFIGURE feels like the least bad solution to me. drivers/block/loop.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 839373451c2b..f00a0209b522 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -992,7 +992,8 @@ loop_set_status_from_info(struct loop_device *lo, static int loop_configure(struct loop_device *lo, fmode_t mode, struct block_device *bdev, - const struct loop_config *config) + const struct loop_config *config, + bool partscan_uevent) { struct file *file = fget(config->fd); struct inode *inode; @@ -1110,15 +1111,21 @@ static int loop_configure(struct loop_device *lo, fmode_t mode, clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state); loop_global_unlock(lo, is_loop); - if (partscan) - loop_reread_partitions(lo); if (!(mode & FMODE_EXCL)) bd_abort_claiming(bdev, loop_configure); + /* + * Now that we are done, reread the partitions with uevent + * re-enabled if appropriate to let userspace know about the + * changes. + */ + dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), !partscan_uevent); + if (partscan) + loop_reread_partitions(lo); + dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0); + error = 0; done: - /* enable and uncork uevent now that we are done */ - dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0); return error; out_unlock: @@ -1130,6 +1136,7 @@ static int loop_configure(struct loop_device *lo, fmode_t mode, fput(file); /* This is safe: open() is still holding a reference. */ module_put(THIS_MODULE); + dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0); goto done; } @@ -1547,7 +1554,7 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode, memset(&config, 0, sizeof(config)); config.fd = arg; - return loop_configure(lo, mode, bdev, &config); + return loop_configure(lo, mode, bdev, &config, false); } case LOOP_CONFIGURE: { struct loop_config config; @@ -1555,7 +1562,7 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode, if (copy_from_user(&config, argp, sizeof(config))) return -EFAULT; - return loop_configure(lo, mode, bdev, &config); + return loop_configure(lo, mode, bdev, &config, true); } case LOOP_CHANGE_FD: return loop_change_fd(lo, bdev, arg);