From patchwork Wed Mar 5 18:17:48 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Filipe Manana X-Patchwork-Id: 14003124 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 4694225485B for ; Wed, 5 Mar 2025 18:17:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741198676; cv=none; b=op/i+hkkYhPW/OR1zceODhNh3jqSWCeaZDf6QDkLL1NW5lOKtPYDb27F0KOijfBof8kC3Awzd+QPGC705Tc35cuzo9xOlT0w3hGAD8AUVDCojuariCSY1t8Q6qjfZ2aq3xh6Su6rsT2oER06F0PV4FUVx4/zPkR3VY3iKdx6bxk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741198676; c=relaxed/simple; bh=XmChc0syTGzI4PfyPGOYDisNWqzuEgQxc3+1lnLelag=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=JKAJJAQMDNcAzJTjXIRh7hzhIUOwiWoOh47DKtKn1CX0iTp/0mDe9OzmSBTF3UdvOEs2hBKDJIh6mPghBZCNFw4VarBumnqKSPHfBJN/nnRrJMxzN8p6lDyqxiivo/6G54YsK/xtr4e6RZ538EhZx/x1YFhz6k3TH/YNY4SGqqA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=B2JScHwr; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="B2JScHwr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9877AC4CEE0 for ; Wed, 5 Mar 2025 18:17:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1741198676; bh=XmChc0syTGzI4PfyPGOYDisNWqzuEgQxc3+1lnLelag=; h=From:To:Subject:Date:In-Reply-To:References:From; b=B2JScHwrhYYVfMvVP7qC9JOJoZvuXyZ8QTV6EJAV2pffb+S1c3FvICy2bvVjiSFnN j9zNipIy4SM9ThkYlufV3c2J3ocMTyvX3+/+UARRqoD+WmYp4IY1i/ArVAOpR26n6y QGPokbM5U37iV0ss0ezYaN+LG0jmriCkcgtEfYbIuGuYjWtSoUiRZ4jUDZR5WpqKaM Yp7UiJcCYKwWf2Hv8jR0Ut0cA3uuNBZVAtxeUChpoBYfEf8l/SD/efq7ZgFTews+a0 SWOpOFpkz/zIvI6l8xsN4o7fIN0LViA1tEhvcx7MgDQYYSfLUrYxaFrTs8ndgMXS8f zExn5CtHTJJDA== From: fdmanana@kernel.org To: linux-btrfs@vger.kernel.org Subject: [PATCH v2 2/4] btrfs: fix non-empty delayed iputs list on unmount due to compressed write workers Date: Wed, 5 Mar 2025 18:17:48 +0000 Message-Id: <617abbacfa82b497460a8c2b3319fbca010037b4.1741198394.git.fdmanana@suse.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Filipe Manana At close_ctree() after we have ran delayed iputs either through explicitly calling btrfs_run_delayed_iputs() or later during the call to btrfs_commit_super() or btrfs_error_commit_super(), we assert that the delayed iputs list is empty. When we have compressed writes this assertion may fail because delayed iputs may have been added to the list after we last ran delayed iputs. This happens like this: 1) We have a compressed write bio executing; 2) We enter close_ctree() and flush the fs_info->endio_write_workers queue which is the queue used for running ordered extent completion; 3) The compressed write bio finishes and enters btrfs_finish_compressed_write_work(), where it calls btrfs_finish_ordered_extent() which in turn calls btrfs_queue_ordered_fn(), which queues a work item in the fs_info->endio_write_workers queue that we have flushed before; 4) At close_ctree() we proceed, run all existing delayed iputs and call btrfs_commit_super() (which also runs delayed iputs), but before we run the following assertion below: ASSERT(list_empty(&fs_info->delayed_iputs)) A delayed iput is added by the step below... 5) The ordered extent completion job queued in step 3 runs and results in creating a delayed iput when dropping the last reference of the ordered extent (a call to btrfs_put_ordered_extent() made from btrfs_finish_one_ordered()); 6) At this point the delayed iputs list is not empty, so the assertion at close_ctree() fails. Fix this by flushing the fs_info->compressed_write_workers queue at close_ctree() before flushing the fs_info->endio_write_workers queue, respecting the queue dependency as the later is responsible for the execution of ordered extent completion. Signed-off-by: Filipe Manana --- fs/btrfs/disk-io.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index b6194ae97361..cae5113b91da 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -4349,6 +4349,18 @@ void __cold close_ctree(struct btrfs_fs_info *fs_info) */ flush_workqueue(fs_info->endio_workers); + /* + * When finishing a compressed write bio we schedule a work queue item + * to finish an ordered extent - btrfs_finish_compressed_write_work() + * calls btrfs_finish_ordered_extent() which in turns does a call to + * btrfs_queue_ordered_fn(), and that queues the ordered extent + * completion either in the endio_write_workers work queue or in the + * fs_info->endio_freespace_worker work queue. We flush those queues + * below, so before we flush them we must flush this queue for the + * workers of compressed writes. + */ + flush_workqueue(fs_info->compressed_write_workers); + /* * After we parked the cleaner kthread, ordered extents may have * completed and created new delayed iputs. If one of the async reclaim