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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F09BAEB64DD for ; Thu, 17 Aug 2023 10:48:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234071AbjHQKr6 (ORCPT ); Thu, 17 Aug 2023 06:47:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52496 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350005AbjHQKr5 (ORCPT ); Thu, 17 Aug 2023 06:47:57 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D2ABD2D5A for ; Thu, 17 Aug 2023 03:47:56 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 62809611D4 for ; Thu, 17 Aug 2023 10:47:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AD04BC433C7; Thu, 17 Aug 2023 10:47:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1692269275; bh=VWlWbqBITMqyfIp+sdjcPDabLMEvtxuPUFsvy9KSORc=; h=From:Subject:Date:To:Cc:From; b=Tn/QwdDz5N7NRqW/Rjyhvwt/RCdSftDFGZzAH2Y5nAH8dXalrGEURxuSxeBKoOKOV +3aoC+7qrXXykiFD+gpJIKgVoTL5jTtShxiuGhIR9nvIZaAHK0j3SLYtkbKr5dpSwp bx4/2JpN+cXUPFiSTyaTSZwTZq4Ie3E8vD8Vq0UCzi+bw1hvfsz91L94wYahjhtu9Y K39A6zl0Mlh5XOD3wkErzEnQyXiJ9bCnFBMYav/UvXOeTS1RuJNl4J+7DYZCHrP4eh 8STyPMvE5SRHDjB5kRKUYe0jhG5B692ImEB0QDPAyHdvXYf/SrkcLluxgDwLFyTYPb XuXUAmzfjkVyA== From: Christian Brauner Subject: [PATCH 0/3] super: allow waiting without s_umount held Date: Thu, 17 Aug 2023 12:47:41 +0200 Message-Id: <20230817-vfs-super-fixes-v3-v1-0-06ddeca7059b@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAM363WQC/x2MQQqDQAwAvyI5N2V3pdL2K6WHdU1qLltJ6CKIf 2/0OAwzGxipkMGz20Cpicm3OsRLB2XO9UMokzOkkPpwjwM2NrTfQoosKxm2HjkV5iE+Ur4F8HB ROp13r7fzmI1w1FzLfKz8cD0PsO9//aGob4AAAAA= To: Jan Kara , Christoph Hellwig Cc: Al Viro , linux-fsdevel@vger.kernel.org, Christian Brauner X-Mailer: b4 0.13-dev-83828 X-Developer-Signature: v=1; a=openpgp-sha256; l=1357; i=brauner@kernel.org; h=from:subject:message-id; bh=VWlWbqBITMqyfIp+sdjcPDabLMEvtxuPUFsvy9KSORc=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMaTc/XWz5LF/0qa6p+K2JydGpP1u/ZDCf1+bTS5ZJ/nUxuW9 3G1qHaUsDGJcDLJiiiwO7Sbhcst5KjYbZWrAzGFlAhnCwMUpABO5KsHwv26d5LzVBi/tm1Jkb/51/b aYecrL5Tf7Stb8WRrRbDunUZLhf1Lut8sWpYs6Fb7cPWHgevn15x0+Vok798y39dvv861aig8A X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Hey everyone, This is an attempty to allow concurrent mounters and iterators to wait on superblock state changes without having to hold s_umount. This is made necessary by recent attempts to open block devices after superblock creation and fixing deadlocks due to blkdev_put() trying to acquire s_umount while s_umount is already held. This is on top of Jan's and Christoph's work in vfs.super. Obviously not for v6.6. I guess this is in between an RFC and meaning it. I hope I got it right but this is intricate. It reliably survives xfstests for btrfs, ext4, and xfs while concurrently having 7 processes running ustat() hammering on @super_blocks and a while true loop that tries to mount a filsystem with an invalid superblock hammering on sget{_fc}() concurrently as well. Thanks and don't hit me over the head with things. Christian Signed-off-by: Christian Brauner --- Christian Brauner (3): super: use super_{lock,unlock}() super: wait for nascent superblocks super: wait until we passed kill super fs/super.c | 327 ++++++++++++++++++++++++++++++++++++++++++----------- include/linux/fs.h | 2 + 2 files changed, 261 insertions(+), 68 deletions(-) --- base-commit: f3aeab61fb15edef1e81828da8dbf0814541e49b change-id: 20230816-vfs-super-fixes-v3-f2cff6192a50