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 431B0CD6114 for ; Mon, 9 Oct 2023 17:56:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377345AbjJIR4r (ORCPT ); Mon, 9 Oct 2023 13:56:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48954 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1376891AbjJIR4p (ORCPT ); Mon, 9 Oct 2023 13:56:45 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB87E94 for ; Mon, 9 Oct 2023 10:56:43 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1DC9EC433C7; Mon, 9 Oct 2023 17:56:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1696874203; bh=4MAFR8eRn/jRjp4WwCXLLtnADd0TxOn+fdtPOWOfo7M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=V2sw+VQv8f0ozr2rncMF7mI6tyJRl5QaqR2TC6GSo7A46dLZWJfthNAfmMJPf2pzs LnkTwKxODVo0wJPr9zWjy/9DzNSr1GdbFBxM49MC9kbCTGnS2gVAUmxNTrKwwCFjez 5Wzcx/ZFFu6UD1dBBwH9OLFFgSOvBazQLPUZodcV2Y1XAnrdh5i61qGvluVxkrAgvb Gh3392etim9H6xDIBoo83BngdlVLuBPzwR3kXPM40jG2XyuXtJ8Y9hyjnY/8Kl7cIm ELuUvZRTewhsRPf95y1sFBxzaD6Ez73MZGX5BugS6xiEXOoBKvUlk5ttjEjv7mAHPh YQXwK1lGvVZEA== Date: Mon, 9 Oct 2023 10:56:41 -0700 From: Jaegeuk Kim To: Chao Yu Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Subject: Re: [f2fs-dev] [PATCH] f2fs: stop iterating f2fs_map_block if hole exists Message-ID: References: <20231003225208.1936359-1-jaegeuk@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/07, Chao Yu wrote: > On 2023/10/4 6:52, Jaegeuk Kim wrote: > > Let's avoid unnecessary f2fs_map_block calls to load extents. > > > > # f2fs_io fadvise willneed 0 4096 /data/local/tmp/test > > > > f2fs_map_blocks: dev = (254,51), ino = 85845, file offset = 386, start blkaddr = 0x34ac00, len = 0x1400, flags = 2, > > f2fs_map_blocks: dev = (254,51), ino = 85845, file offset = 5506, start blkaddr = 0x34c200, len = 0x1000, flags = 2, > > f2fs_map_blocks: dev = (254,51), ino = 85845, file offset = 9602, start blkaddr = 0x34d600, len = 0x1200, flags = 2, > > f2fs_map_blocks: dev = (254,51), ino = 85845, file offset = 14210, start blkaddr = 0x34ec00, len = 0x400, flags = 2, > > f2fs_map_blocks: dev = (254,51), ino = 85845, file offset = 15235, start blkaddr = 0x34f401, len = 0xbff, flags = 2, > > f2fs_map_blocks: dev = (254,51), ino = 85845, file offset = 18306, start blkaddr = 0x350200, len = 0x1200, flags = 2 > > f2fs_map_blocks: dev = (254,51), ino = 85845, file offset = 22915, start blkaddr = 0x351601, len = 0xa7d, flags = 2 > > f2fs_map_blocks: dev = (254,51), ino = 85845, file offset = 25600, start blkaddr = 0x351601, len = 0x0, flags = 0 > > f2fs_map_blocks: dev = (254,51), ino = 85845, file offset = 25601, start blkaddr = 0x351601, len = 0x0, flags = 0 > > f2fs_map_blocks: dev = (254,51), ino = 85845, file offset = 25602, start blkaddr = 0x351601, len = 0x0, flags = 0 > > ... > > f2fs_map_blocks: dev = (254,51), ino = 85845, file offset = 1037188, start blkaddr = 0x351601, len = 0x0, flags = 0 > > f2fs_map_blocks: dev = (254,51), ino = 85845, file offset = 1038206, start blkaddr = 0x351601, len = 0x0, flags = 0 > > f2fs_map_blocks: dev = (254,51), ino = 85845, file offset = 1039224, start blkaddr = 0x351601, len = 0x0, flags = 0 > > f2fs_map_blocks: dev = (254,51), ino = 85845, file offset = 2075548, start blkaddr = 0x351601, len = 0x0, flags = 0 > > Jaegeuk, > > Not sure, but it looks it's due to f2fs_precache_extents() will traverse file > w/ range [0, max_file_blocks), since data which exceeds EOF will always be zero, > so it's not necessary to precache its mapping info, so we'd better adjust upper > boundary to i_size rather than max_file_blocks(). > > > > > Signed-off-by: Jaegeuk Kim > > --- > > fs/f2fs/file.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > > index 161826c6e200..2403fd1de5a0 100644 > > --- a/fs/f2fs/file.c > > +++ b/fs/f2fs/file.c > > @@ -3270,7 +3270,7 @@ int f2fs_precache_extents(struct inode *inode) > > f2fs_down_write(&fi->i_gc_rwsem[WRITE]); > > err = f2fs_map_blocks(inode, &map, F2FS_GET_BLOCK_PRECACHE); > > f2fs_up_write(&fi->i_gc_rwsem[WRITE]); > > - if (err) > > + if (err || !map.m_len) > Well, if there is a hole in the head of file, it may break here rather > than precaching following valid map info. > > What about passing parameter offset|len from f2fs_file_fadvise() to > f2fs_precache_extents(), and then precaching mapping info on demand. I'd rather stop reading metadata if it meets a hole within i_size, since this gives benefits when reading the entire non-hole case, FWIW. Rather than that, I think generic readahead flow can hide the metadata loading. > > Thanks, > > > return err; > > map.m_lblk = m_next_extent;