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bh=jFycCzBUY2ndD2OB9cK6rohJ6DSuRX1OY1L3NUKQzi0=; b=ULNWb1SasnKwBzqjYFKgnzIc+p i5ooGajKzaqnFukW9tfwNFxmRxDRHPFfC0DW4BeXZKUOOnBL/WVRQkY55Bz2OBZEzYVcyMB1vJe+R HW2lxs1bLCLe1e8+DFSuIWO5h8+1Fj3aZQVpDrpKuiv7VVzFgosEC2p6NYuowbw3twxw=; Received: from mail.kernel.org ([198.145.29.99]) by sfi-mx-1.v28.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) id 1i7FCG-005UT0-NV for linux-f2fs-devel@lists.sourceforge.net; Mon, 09 Sep 2019 08:38:53 +0000 Received: from localhost (unknown [148.69.85.38]) (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 AE91A218AC; Mon, 9 Sep 2019 08:38:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568018327; bh=h/O/BE7OIazqYv1sKFu2+r3tD8HYU7J0+05Vtn7XDSA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=OFGzCFKLEGpb4HSYK7wqOjse7xpWIrMhPEeXkD5UJUY6rQOqD7XLteS5Im/EzHQxL e9GQlHSK5V9bmKh5ynGYZamrLck/aUUIv76XKXs4wBfzqiL9FMDLu1SHl/N4f91KXP 0n2+vYDxFLZ4jTvOpTdl5sJC9YQs1DcPE3mplFl0= Date: Mon, 9 Sep 2019 09:38:44 +0100 From: Jaegeuk Kim To: Chao Yu Message-ID: <20190909083844.GC25724@jaegeuk-macbookpro.roam.corp.google.com> References: <20190909012532.20454-1-jaegeuk@kernel.org> <20190909012532.20454-2-jaegeuk@kernel.org> <20190909073011.GA21625@jaegeuk-macbookpro.roam.corp.google.com> <5a473076-14b8-768a-62ac-f686e850d5a6@huawei.com> <20190909080108.GC21625@jaegeuk-macbookpro.roam.corp.google.com> <20190909082112.GA25724@jaegeuk-macbookpro.roam.corp.google.com> <2f5b844c-f722-6a80-a4ab-61bdd72b8be4@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <2f5b844c-f722-6a80-a4ab-61bdd72b8be4@huawei.com> User-Agent: Mutt/1.8.2 (2017-04-18) X-Headers-End: 1i7FCG-005UT0-NV Subject: Re: [f2fs-dev] [PATCH 2/2] f2fs: avoid infinite GC loop due to stale atomic files X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-f2fs-devel@lists.sourceforge.net, g@jaegeuk-macbookpro.roam.corp.google.com, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On 09/09, Chao Yu wrote: > On 2019/9/9 16:21, Jaegeuk Kim wrote: > > On 09/09, Chao Yu wrote: > >> On 2019/9/9 16:01, Jaegeuk Kim wrote: > >>> On 09/09, Chao Yu wrote: > >>>> On 2019/9/9 15:30, Jaegeuk Kim wrote: > >>>>> On 09/09, Chao Yu wrote: > >>>>>> On 2019/9/9 9:25, Jaegeuk Kim wrote: > >>>>>>> If committing atomic pages is failed when doing f2fs_do_sync_file(), we can > >>>>>>> get commited pages but atomic_file being still set like: > >>>>>>> > >>>>>>> - inmem: 0, atomic IO: 4 (Max. 10), volatile IO: 0 (Max. 0) > >>>>>>> > >>>>>>> If GC selects this block, we can get an infinite loop like this: > >>>>>>> > >>>>>>> f2fs_submit_page_bio: dev = (253,7), ino = 2, page_index = 0x2359a8, oldaddr = 0x2359a8, newaddr = 0x2359a8, rw = READ(), type = COLD_DATA > >>>>>>> f2fs_submit_read_bio: dev = (253,7)/(253,7), rw = READ(), DATA, sector = 18533696, size = 4096 > >>>>>>> f2fs_get_victim: dev = (253,7), type = No TYPE, policy = (Foreground GC, LFS-mode, Greedy), victim = 4355, cost = 1, ofs_unit = 1, pre_victim_secno = 4355, prefree = 0, free = 234 > >>>>>>> f2fs_iget: dev = (253,7), ino = 6247, pino = 5845, i_mode = 0x81b0, i_size = 319488, i_nlink = 1, i_blocks = 624, i_advise = 0x2c > >>>>>>> f2fs_submit_page_bio: dev = (253,7), ino = 2, page_index = 0x2359a8, oldaddr = 0x2359a8, newaddr = 0x2359a8, rw = READ(), type = COLD_DATA > >>>>>>> f2fs_submit_read_bio: dev = (253,7)/(253,7), rw = READ(), DATA, sector = 18533696, size = 4096 > >>>>>>> f2fs_get_victim: dev = (253,7), type = No TYPE, policy = (Foreground GC, LFS-mode, Greedy), victim = 4355, cost = 1, ofs_unit = 1, pre_victim_secno = 4355, prefree = 0, free = 234 > >>>>>>> f2fs_iget: dev = (253,7), ino = 6247, pino = 5845, i_mode = 0x81b0, i_size = 319488, i_nlink = 1, i_blocks = 624, i_advise = 0x2c > >>>>>>> > >>>>>>> In that moment, we can observe: > >>>>>>> > >>>>>>> [Before] > >>>>>>> Try to move 5084219 blocks (BG: 384508) > >>>>>>> - data blocks : 4962373 (274483) > >>>>>>> - node blocks : 121846 (110025) > >>>>>>> Skipped : atomic write 4534686 (10) > >>>>>>> > >>>>>>> [After] > >>>>>>> Try to move 5088973 blocks (BG: 384508) > >>>>>>> - data blocks : 4967127 (274483) > >>>>>>> - node blocks : 121846 (110025) > >>>>>>> Skipped : atomic write 4539440 (10) > >>>>>>> > >>>>>>> Signed-off-by: Jaegeuk Kim > >>>>>>> --- > >>>>>>> fs/f2fs/file.c | 10 +++++----- > >>>>>>> 1 file changed, 5 insertions(+), 5 deletions(-) > >>>>>>> > >>>>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > >>>>>>> index 7ae2f3bd8c2f..68b6da734e5f 100644 > >>>>>>> --- a/fs/f2fs/file.c > >>>>>>> +++ b/fs/f2fs/file.c > >>>>>>> @@ -1997,11 +1997,11 @@ static int f2fs_ioc_commit_atomic_write(struct file *filp) > >>>>>>> goto err_out; > >>>>>>> > >>>>>>> ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 0, true); > >>>>>>> - if (!ret) { > >>>>>>> - clear_inode_flag(inode, FI_ATOMIC_FILE); > >>>>>>> - F2FS_I(inode)->i_gc_failures[GC_FAILURE_ATOMIC] = 0; > >>>>>>> - stat_dec_atomic_write(inode); > >>>>>>> - } > >>>>>>> + > >>>>>>> + /* doesn't need to check error */ > >>>>>>> + clear_inode_flag(inode, FI_ATOMIC_FILE); > >>>>>>> + F2FS_I(inode)->i_gc_failures[GC_FAILURE_ATOMIC] = 0; > >>>>>>> + stat_dec_atomic_write(inode); > >>>>>> > >>>>>> If there are still valid atomic write pages linked in .inmem_pages, it may cause > >>>>>> memory leak when we just clear FI_ATOMIC_FILE flag. > >>>>> > >>>>> f2fs_commit_inmem_pages() should have flushed them. > >>>> > >>>> Oh, we failed to flush its nodes. > >>>> > >>>> However we won't clear such info if we failed to flush inmen pages, it looks > >>>> inconsistent. > >>>> > >>>> Any interface needed to drop inmem pages or clear ATOMIC_FILE flag in that two > >>>> error path? I'm not very clear how sqlite handle such error. > >>> > >>> f2fs_drop_inmem_pages() did that, but not in this case. > >> > >> What I mean is, for any error returned from atomic_commit() interface, should > >> userspace application handle it with consistent way, like trigger > >> f2fs_drop_inmem_pages(), so we don't need to handle it inside atomic_commit(). > > > > f2fs_ioc_abort_volatile_write() will be triggered. > > If userspace can do this, we can get rid of this patch, or am I missing sth? We don't know when that will come. And, other threads are waiting for GC here. > > - f2fs_ioc_abort_volatile_write > - f2fs_drop_inmem_pages > - clear_inode_flag(inode, FI_ATOMIC_FILE); > - fi->i_gc_failures[GC_FAILURE_ATOMIC] = 0; > - stat_dec_atomic_write(inode); > > > > >> > >>> > >>>> > >>>> Thanks, > >>>> > >>>>> > >>>>>> > >>>>>> So my question is why below logic didn't handle such condition well? > >>>>>> > >>>>>> f2fs_gc() > >>>>>> > >>>>>> if (has_not_enough_free_secs(sbi, sec_freed, 0)) { > >>>>>> if (skipped_round <= MAX_SKIP_GC_COUNT || > >>>>>> skipped_round * 2 < round) { > >>>>>> segno = NULL_SEGNO; > >>>>>> goto gc_more; > >>>>>> } > >>>>>> > >>>>>> if (first_skipped < last_skipped && > >>>>>> (last_skipped - first_skipped) > > >>>>>> sbi->skipped_gc_rwsem) { > >>>>>> f2fs_drop_inmem_pages_all(sbi, true); > >>>>> > >>>>> This is doing nothing, since f2fs_commit_inmem_pages() removed the inode > >>>>> from inmem list. > >>>>> > >>>>>> segno = NULL_SEGNO; > >>>>>> goto gc_more; > >>>>>> } > >>>>>> if (gc_type == FG_GC && !is_sbi_flag_set(sbi, SBI_CP_DISABLED)) > >>>>>> ret = f2fs_write_checkpoint(sbi, &cpc); > >>>>>> } > >>>>>> > >>>>>>> } else { > >>>>>>> ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 1, false); > >>>>>>> } > >>>>>>> > >>>>> . > >>>>> > >>> . > >>> > > . > > _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel