From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yunlong Song Subject: Re: [PATCH] f2fs: discard small invalid blocks in current active segments Date: Mon, 28 Aug 2017 21:21:29 +0800 Message-ID: <61d97244-c4e5-0008-ab30-fc52a05e0b24@huawei.com> References: <1503751772-158812-1-git-send-email-yunlong.song@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Chao Yu , jaegeuk@kernel.org, chao@kernel.org, yunlong.song@icloud.com Cc: miaoxie@huawei.com, bintian.wang@huawei.com, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org List-Id: linux-f2fs-devel.lists.sourceforge.net How? Can the invalid blocks of file A be discarded, if file B is alive all the time and fggc_threshold is 507 ? On 2017/8/28 17:59, Chao Yu wrote: > On 2017/8/26 20:49, Yunlong Song wrote: >> 1. write file A with 5 blocks to current empty active segment >> 2. remove file A >> 3. write checkpoint >> 4. write file B with 507 blocks to the same active segment >> >> If file B is alive all the time, the blocks used by file A will never be >> discarded. So current active segment should also be treated as a candidate >> for small discards. > I don't think that would be a big issue, since there will not be any freezing > log headers, once log header moves, later invalid blocks could be discarded. > > Thanks, > >> Signed-off-by: Yunlong Song >> --- >> fs/f2fs/segment.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c >> index 8375257..a2e7c8f 100644 >> --- a/fs/f2fs/segment.c >> +++ b/fs/f2fs/segment.c >> @@ -1339,7 +1339,9 @@ static bool add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc, >> return false; >> >> if (!force) { >> - if (!test_opt(sbi, DISCARD) || !se->valid_blocks || >> + if (!test_opt(sbi, DISCARD) || >> + (!se->valid_blocks && >> + !IS_CURSEG(sbi, cpc->trim_start)) || >> SM_I(sbi)->dcc_info->nr_discards >= >> SM_I(sbi)->dcc_info->max_discards) >> return false; >> > > . > -- Thanks, Yunlong Song