From patchwork Wed Mar 5 17:45:48 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Filipe Manana X-Patchwork-Id: 14003096 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 37686250C0D for ; Wed, 5 Mar 2025 17:45:57 +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=1741196758; cv=none; b=ZvXBkM4HAnoD8am/jHvvijxkiDMJUDvmdKgfqpvCcvuxlqocCK+aFE+lDhs9FKbOifCLJFtgrxRn9JwJQI28fb64bn1l7/12qnWJdH9elpN6s7dtLeyxwgo38FQ95ShlgNYxA0gnYKeKilCsZM3QMSIAp/BV1BLrbVTq59eiW64= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741196758; c=relaxed/simple; bh=2UyXHbsP9U4V63YhVQ8jwT7pZp3V8BmgdW6TRlynpCg=; h=From:To:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=fvXeuaCv7mpM53eEJjBLFGEGZeE7XoLXB+wNGG+am5/ihJZqqjXHsJvDtPuof1haRf5ZlZSp1IFQPvKnrI+LwD+pVLwI3Gvjwx7FxxuMGXw/EQCU4Kt8Om2jQj3ouJzWf2x3BhoLy1haNGPf7Xr1d6QvIWwVWSaP5yYj7+ekBSY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MWw7hWaA; 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="MWw7hWaA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 28970C4CED1 for ; Wed, 5 Mar 2025 17:45:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1741196757; bh=2UyXHbsP9U4V63YhVQ8jwT7pZp3V8BmgdW6TRlynpCg=; h=From:To:Subject:Date:In-Reply-To:References:From; b=MWw7hWaAh19U9iEasW40snB2XemXlh97gjo6UuIAdd1CHeASlvk+5jWmKy3iz2BhV FJRhgk1CECtI9y600wKC1beSe4O2u+UdfnysPTPD965PFD+gnWkM2tETGbSYKP3Vn+ ZxtQXIgiuVGA2/moVzFtp58Va0w+1mJLa6ylp5Ky6ycFEymrvnty5kbNiOhELFb8/e cL3oyJI4Zt2DkIYsYUL3JxPMJu920fmBGH5kEdOAJHDM8IdKICQR9RAbD/qWGCiDHG ggpu1ndXTjdlgfMvGplztccb65b4Zy40sdeucc7s7seYHaenEg2Ai0WgHzuRPiq6Hk ECS4fF9FhFX+g== From: fdmanana@kernel.org To: linux-btrfs@vger.kernel.org Subject: [PATCH 2/4] btrfs: fix non-empty delayed iputs list on unmount due to compressed write workers Date: Wed, 5 Mar 2025 17:45:48 +0000 Message-Id: <3111c41408f2cb11096b9fe002a08fd09b8fb89c.1741196484.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 | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index df8e075e69a3..95277c05fefa 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -4350,6 +4350,19 @@ void __cold close_ctree(struct btrfs_fs_info *fs_info) if (fs_info->endio_workers) 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. + */ + if (fs_info->compressed_write_workers) + 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