From mboxrd@z Thu Jan 1 00:00:00 1970 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B25EEE7719A for ; Wed, 8 Jan 2025 09:26:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=l/31ESR3+qEAHHMxPuf7j9P2G6uDf3ZUExmKKhtWzmA=; b=idJkW8ciFq9b6Pc4lQxSQnRPFj ic0m7XKuG3rKKfcrXdLfkbfssp9qGISk24L+gH1rci0hqI8sVdmmiDsHFkkMNu7i1DWfhZUdgCt04 9/KwmX35ZFZ3+yf0pRQaONoOX5oq/UtBK++dCMWOniMfXAzpZ9Djl8rdnAQsj3hfs/ew3T/hluwYS URHCko6WNSAAa4GFclrfutQtgovnyOnt1ZBUC3KoHQIvNSOeDvi7ZEMVy0IuTEmLk3NSMfytqmUPb 3OirUu+CcVtQ2wLLHqHl2ojK+h76x6FtRSslbQdqzjnaEIQtt4WQtmQhDurAqGqgtIHUSpPYQrrey xYpkAtUA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tVSKE-00000007m16-0wEU; Wed, 08 Jan 2025 09:26:06 +0000 Received: from 2a02-8389-2341-5b80-e44b-b36a-6403-8f06.cable.dynamic.v6.surfer.at ([2a02:8389:2341:5b80:e44b:b36a:6403:8f06] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tVSKB-00000007lwB-274R; Wed, 08 Jan 2025 09:26:04 +0000 From: Christoph Hellwig To: Jens Axboe Cc: Damien Le Moal , Ming Lei , Nilay Shroff , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, nbd@other.debian.org, linux-scsi@vger.kernel.org, usb-storage@lists.one-eyed-alien.net Subject: [PATCH 10/10] loop: fix queue freeze vs limits lock order Date: Wed, 8 Jan 2025 10:25:07 +0100 Message-ID: <20250108092520.1325324-11-hch@lst.de> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20250108092520.1325324-1-hch@lst.de> References: <20250108092520.1325324-1-hch@lst.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org Match the locking order used by the core block code by only freezing the queue after taking the limits lock using the queue_limits_commit_update_frozen helper and document the callers that do not freeze the queue at all. Signed-off-by: Christoph Hellwig --- drivers/block/loop.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 560d6d5879d6..15e486baa223 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -311,6 +311,13 @@ static void loop_clear_limits(struct loop_device *lo, int mode) lim.discard_granularity = 0; } + /* + * XXX: this updates the queue limits without freezing the queue, which + * is against the locking protocol and dangerous. But we can't just + * freeze the queue as we're inside the ->queue_rq method here. So this + * should move out into a workqueue unless we get the file operations to + * advertise if they support specific fallocate operations. + */ queue_limits_commit_update(lo->lo_queue, &lim); } @@ -1091,6 +1098,7 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode, lim = queue_limits_start_update(lo->lo_queue); loop_update_limits(lo, &lim, config->block_size); + /* No need to freeze the queue as the device isn't bound yet. */ error = queue_limits_commit_update(lo->lo_queue, &lim); if (error) goto out_unlock; @@ -1151,7 +1159,12 @@ static void __loop_clr_fd(struct loop_device *lo) lo->lo_sizelimit = 0; memset(lo->lo_file_name, 0, LO_NAME_SIZE); - /* reset the block size to the default */ + /* + * Reset the block size to the default. + * + * No queue freezing needed because this is called from the final + * ->release call only, so there can't be any outstanding I/O. + */ lim = queue_limits_start_update(lo->lo_queue); lim.logical_block_size = SECTOR_SIZE; lim.physical_block_size = SECTOR_SIZE; @@ -1471,9 +1484,10 @@ static int loop_set_block_size(struct loop_device *lo, unsigned long arg) sync_blockdev(lo->lo_device); invalidate_bdev(lo->lo_device); - blk_mq_freeze_queue(lo->lo_queue); lim = queue_limits_start_update(lo->lo_queue); loop_update_limits(lo, &lim, arg); + + blk_mq_freeze_queue(lo->lo_queue); err = queue_limits_commit_update(lo->lo_queue, &lim); loop_update_dio(lo); blk_mq_unfreeze_queue(lo->lo_queue); -- 2.45.2