From patchwork Mon Jan 24 18:44:57 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 535601 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 1D22BC433EF for ; Mon, 24 Jan 2022 21:06:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1444242AbiAXVG4 (ORCPT ); Mon, 24 Jan 2022 16:06:56 -0500 Received: from dfw.source.kernel.org ([139.178.84.217]:42824 "EHLO dfw.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1358918AbiAXUtD (ORCPT ); Mon, 24 Jan 2022 15:49:03 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id F042660E8D; Mon, 24 Jan 2022 20:49:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C9D4BC340E5; Mon, 24 Jan 2022 20:48:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643057340; bh=kwp53B5aQK63xTNBGxMPd0Dfca1gi9Z5Waz2Qy/vQRM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=w21xIvLkGAcX2so7h8u6IJExhP4U1JA4F42m3X3HM8PzkC2duJlty96EMhFOlq9Gr +y8ymZETLldd9a6mNhO42B/H5qbgLAtc96/LWmeGE1NswAnXVYxeO19iHVGW3or1gU 1hOZ789zYRdqMf1Dv6lPVgRr657cNLq0wvBvwuKQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hyeong-Jun Kim , Sungjong Seo , Youngjin Gil , Chao Yu , Jaegeuk Kim Subject: [PATCH 5.15 780/846] f2fs: compress: fix potential deadlock of compress file Date: Mon, 24 Jan 2022 19:44:57 +0100 Message-Id: <20220124184127.866064172@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220124184100.867127425@linuxfoundation.org> References: <20220124184100.867127425@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Hyeong-Jun Kim commit 7377e853967ba45bf409e3b5536624d2cbc99f21 upstream. There is a potential deadlock between writeback process and a process performing write_begin() or write_cache_pages() while trying to write same compress file, but not compressable, as below: [Process A] - doing checkpoint [Process B] [Process C] f2fs_write_cache_pages() - lock_page() [all pages in cluster, 0-31] - f2fs_write_multi_pages() - f2fs_write_raw_pages() - f2fs_write_single_data_page() - f2fs_do_write_data_page() - return -EAGAIN [f2fs_trylock_op() failed] - unlock_page(page) [e.g., page 0] - generic_perform_write() - f2fs_write_begin() - f2fs_prepare_compress_overwrite() - prepare_compress_overwrite() - lock_page() [e.g., page 0] - lock_page() [e.g., page 1] - lock_page(page) [e.g., page 0] Since there is no compress process, it is no longer necessary to hold locks on every pages in cluster within f2fs_write_raw_pages(). This patch changes f2fs_write_raw_pages() to release all locks first and then perform write same as the non-compress file in f2fs_write_cache_pages(). Fixes: 4c8ff7095bef ("f2fs: support data compression") Signed-off-by: Hyeong-Jun Kim Signed-off-by: Sungjong Seo Signed-off-by: Youngjin Gil Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Greg Kroah-Hartman --- fs/f2fs/compress.c | 50 ++++++++++++++++++++++---------------------------- 1 file changed, 22 insertions(+), 28 deletions(-) --- a/fs/f2fs/compress.c +++ b/fs/f2fs/compress.c @@ -1448,25 +1448,38 @@ static int f2fs_write_raw_pages(struct c enum iostat_type io_type) { struct address_space *mapping = cc->inode->i_mapping; - int _submitted, compr_blocks, ret; - int i = -1, err = 0; + int _submitted, compr_blocks, ret, i; compr_blocks = f2fs_compressed_blocks(cc); - if (compr_blocks < 0) { - err = compr_blocks; - goto out_err; + + for (i = 0; i < cc->cluster_size; i++) { + if (!cc->rpages[i]) + continue; + + redirty_page_for_writepage(wbc, cc->rpages[i]); + unlock_page(cc->rpages[i]); } + if (compr_blocks < 0) + return compr_blocks; + for (i = 0; i < cc->cluster_size; i++) { if (!cc->rpages[i]) continue; retry_write: + lock_page(cc->rpages[i]); + if (cc->rpages[i]->mapping != mapping) { +continue_unlock: unlock_page(cc->rpages[i]); continue; } - BUG_ON(!PageLocked(cc->rpages[i])); + if (!PageDirty(cc->rpages[i])) + goto continue_unlock; + + if (!clear_page_dirty_for_io(cc->rpages[i])) + goto continue_unlock; ret = f2fs_write_single_data_page(cc->rpages[i], &_submitted, NULL, NULL, wbc, io_type, @@ -1481,26 +1494,15 @@ retry_write: * avoid deadlock caused by cluster update race * from foreground operation. */ - if (IS_NOQUOTA(cc->inode)) { - err = 0; - goto out_err; - } + if (IS_NOQUOTA(cc->inode)) + return 0; ret = 0; cond_resched(); congestion_wait(BLK_RW_ASYNC, DEFAULT_IO_TIMEOUT); - lock_page(cc->rpages[i]); - - if (!PageDirty(cc->rpages[i])) { - unlock_page(cc->rpages[i]); - continue; - } - - clear_page_dirty_for_io(cc->rpages[i]); goto retry_write; } - err = ret; - goto out_err; + return ret; } *submitted += _submitted; @@ -1509,14 +1511,6 @@ retry_write: f2fs_balance_fs(F2FS_M_SB(mapping), true); return 0; -out_err: - for (++i; i < cc->cluster_size; i++) { - if (!cc->rpages[i]) - continue; - redirty_page_for_writepage(wbc, cc->rpages[i]); - unlock_page(cc->rpages[i]); - } - return err; } int f2fs_write_multi_pages(struct compress_ctx *cc,