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 X-Spam-Level: X-Spam-Status: No, score=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C9004C433DF for ; Thu, 28 May 2020 19:18:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A6504207BC for ; Thu, 28 May 2020 19:18:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590693522; bh=ENwJXkJLKZRRsPK+WQo6kcGcxKkeYsu9FJkyfV7BrsY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=bmQELStCF/8dVglkREWQooA4MY4yODdEZxIxpY90HDPuEbamS+2WTAbRlnIgD0z3v Bmog5y7ipQ6yDUJv5efoUMMHYnYbDPQWuf60ogrerW/ODjrYSiptuDeCXLfW99jbtf 2bOjxw5tZpFHVTuzZu+rE3veCasLS/6ZSPC4S12s= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406254AbgE1TSm (ORCPT ); Thu, 28 May 2020 15:18:42 -0400 Received: from mail.kernel.org ([198.145.29.99]:47288 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405596AbgE1TSk (ORCPT ); Thu, 28 May 2020 15:18:40 -0400 Received: from localhost (unknown [104.132.1.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 90E0D2075A; Thu, 28 May 2020 19:18:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590693519; bh=ENwJXkJLKZRRsPK+WQo6kcGcxKkeYsu9FJkyfV7BrsY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=AxJ5emo9TW7QwGwPSsV9Dp1eJDxxvH4nmRepMbV4kjwQoATkDAQwKTqE05mMxWE2b U36vLeleBvo0SwmbPZfbuGe4GbUsq9AS8XxCMEXyo6gJx/WucGGSc5x/+Nhhvjozbk OXcjyo8rgkphmvKFpjCzbLVST1jQ5R9N5dsyWg68= Date: Thu, 28 May 2020 12:18:39 -0700 From: Jaegeuk Kim To: Chao Yu Cc: Sahitya Tummala , linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [f2fs-dev] [PATCH] f2fs: fix retry logic in f2fs_write_cache_pages() Message-ID: <20200528191839.GA180586@google.com> References: <1590546056-17871-1-git-send-email-stummala@codeaurora.org> <1d54379e-35c7-76e0-0c8a-d89bfcecb935@huawei.com> <78d2f29b-3ec0-39bc-46cf-88e82f1970c9@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <78d2f29b-3ec0-39bc-46cf-88e82f1970c9@huawei.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/28, Chao Yu wrote: > On 2020/5/28 10:45, Chao Yu wrote: > > On 2020/5/27 10:20, Sahitya Tummala wrote: > >> In case a compressed file is getting overwritten, the current retry > >> logic doesn't include the current page to be retried now as it sets > >> the new start index as 0 and new end index as writeback_index - 1. > >> This causes the corresponding cluster to be uncompressed and written > >> as normal pages without compression. Fix this by allowing writeback to > >> be retried for the current page as well (in case of compressed page > >> getting retried due to index mismatch with cluster index). So that > >> this cluster can be written compressed in case of overwrite. > >> > >> Signed-off-by: Sahitya Tummala > >> --- > >> fs/f2fs/data.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > >> index 4af5fcd..bfd1df4 100644 > >> --- a/fs/f2fs/data.c > >> +++ b/fs/f2fs/data.c > >> @@ -3024,7 +3024,7 @@ static int f2fs_write_cache_pages(struct address_space *mapping, > >> if ((!cycled && !done) || retry) { > > > > IMO, we add retry logic in wrong place, you can see that cycled value is > > zero only if wbc->range_cyclic is true, in that case writeback_index is valid. > > > > However if retry is true and wbc->range_cyclic is false, then writeback_index > > would be uninitialized variable. > > > > Thoughts? > > > > Thanks, > > > >> cycled = 1; > >> index = 0; > >> - end = writeback_index - 1; > > BTW, I notice that range_cyclic writeback flow was refactored in below commit, > and skeleton of f2fs.writepages was copied from mm/page-writeback.c::write_cache_pages(), > I guess we need follow that change. > > 64081362e8ff ("mm/page-writeback.c: fix range_cyclic writeback vs writepages deadlock") Is that something like this? --- fs/f2fs/data.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index 48a622b95b76e..28fcdf0d4dcb9 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -2861,7 +2861,6 @@ static int f2fs_write_cache_pages(struct address_space *mapping, pgoff_t index; pgoff_t end; /* Inclusive */ pgoff_t done_index; - int cycled; int range_whole = 0; xa_mark_t tag; int nwritten = 0; @@ -2879,17 +2878,12 @@ static int f2fs_write_cache_pages(struct address_space *mapping, if (wbc->range_cyclic) { writeback_index = mapping->writeback_index; /* prev offset */ index = writeback_index; - if (index == 0) - cycled = 1; - else - cycled = 0; end = -1; } else { index = wbc->range_start >> PAGE_SHIFT; end = wbc->range_end >> PAGE_SHIFT; if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) range_whole = 1; - cycled = 1; /* ignore range_cyclic tests */ } if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) tag = PAGECACHE_TAG_TOWRITE; @@ -3054,10 +3048,9 @@ static int f2fs_write_cache_pages(struct address_space *mapping, } } #endif - if ((!cycled && !done) || retry) { - cycled = 1; + if (retry) { index = 0; - end = writeback_index - 1; + end = -1; goto retry; } if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0)) -- 2.27.0.rc0.183.gde8f92d652-goog