From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaegeuk Kim Subject: Re: [PATCH 1/2] f2fs: fix to commit bio cache after flushing node pages Date: Wed, 28 Sep 2016 13:19:32 -0700 Message-ID: <20160928201932.GA40613@jaegeuk> References: <1474906193-6487-1-git-send-email-chao@kernel.org> <20160926183321.GB33149@jaegeuk> <4a95fcaa-413c-5018-70a3-19480a39c59a@huawei.com> <20160927013923.GA35593@jaegeuk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191] helo=mx.sourceforge.net) by sfs-ml-4.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1bpLKR-0006W3-Pa for linux-f2fs-devel@lists.sourceforge.net; Wed, 28 Sep 2016 20:19:43 +0000 Received: from mail.kernel.org ([198.145.29.136]) by sog-mx-1.v43.ch3.sourceforge.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.76) id 1bpLKP-0005sD-Mr for linux-f2fs-devel@lists.sourceforge.net; Wed, 28 Sep 2016 20:19:43 +0000 Content-Disposition: inline In-Reply-To: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: Chao Yu Cc: Chao Yu , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net On Tue, Sep 27, 2016 at 10:09:03AM +0800, Chao Yu wrote: > On 2016/9/27 9:39, Jaegeuk Kim wrote: > > On Tue, Sep 27, 2016 at 08:57:41AM +0800, Chao Yu wrote: > >> Hi Jaegeuk, > >> > >> On 2016/9/27 2:33, Jaegeuk Kim wrote: > >>> Hi Chao, > >>> > >>> On Tue, Sep 27, 2016 at 12:09:52AM +0800, Chao Yu wrote: > >>>> From: Chao Yu > >>>> > >>>> In sync_node_pages, we won't check and commit last merged pages in private > >>>> bio cache of f2fs, as these pages were taged as writeback, someone who is > >>>> waiting for writebacking of the page will be blocked until the cache was > >>>> committed by someone else. > >>>> > >>>> We need to commit node type bio cache to avoid potential deadlock or long > >>>> delay of waiting writeback. > >>>> > >>>> Signed-off-by: Chao Yu > >>>> --- > >>>> fs/f2fs/node.c | 11 +++++++++-- > >>>> 1 file changed, 9 insertions(+), 2 deletions(-) > >>>> > >>>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c > >>>> index 9faddcd..f73f774 100644 > >>>> --- a/fs/f2fs/node.c > >>>> +++ b/fs/f2fs/node.c > >>>> @@ -1416,6 +1416,7 @@ int sync_node_pages(struct f2fs_sb_info *sbi, struct writeback_control *wbc) > >>>> struct pagevec pvec; > >>>> int step = 0; > >>>> int nwritten = 0; > >>>> + int ret = 0; > >>>> > >>>> pagevec_init(&pvec, 0); > >>>> > >>>> @@ -1436,7 +1437,8 @@ next_step: > >>>> > >>>> if (unlikely(f2fs_cp_error(sbi))) { > >>>> pagevec_release(&pvec); > >>>> - return -EIO; > >>>> + ret = -EIO; > >>>> + goto out; > >>>> } > >>>> > >>>> /* > >>>> @@ -1487,6 +1489,8 @@ continue_unlock: > >>>> > >>>> if (NODE_MAPPING(sbi)->a_ops->writepage(page, wbc)) > >>>> unlock_page(page); > >>>> + else > >>>> + nwritten++; > >>>> > >>>> if (--wbc->nr_to_write == 0) > >>>> break; > >>>> @@ -1504,7 +1508,10 @@ continue_unlock: > >>>> step++; > >>>> goto next_step; > >>>> } > >>>> - return nwritten; > >>>> +out: > >>>> + if (nwritten) > >>>> + f2fs_submit_merged_bio(sbi, NODE, WRITE); > >>> > >>> IIRC, we don't need to flush this, since f2fs_submit_merged_bio_cond() would > >>> handle this in f2fs_wait_on_page_writeback(). > >> > >> Yes, it covers all the cases in f2fs private codes, but there are still some > >> codes in mm or fs directory, and they didn't use f2fs_wait_on_page_writeback > >> when waiting page writeback. Such as do_writepages && filemap_fdatawait in > >> __writeback_single_inode... > > > > The do_writepages() is okay, which will call f2fs_write_node_pages(). > > The __writeback_single_inode() won't do filemap_fdatawait() with WB_SYNC_ALL. > > We don't need to take care of truncation as well. > > > > Any missing one? > > Another is: while testing with first version of checkpoint error injection, I > encounter below dump stack: > > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > mount D ffff8801c1bf7960 0 97685 97397 0x00080000 > ffff8801c1bf7960 ffff8801c1bf7930 ffff880175900000 ffff8801c1bf7980 > ffff8801c1bf8000 0000000000000000 7fffffffffffffff ffff88021f7be340 > ffffffff817c8880 ffff8801c1bf7978 ffffffff817c80a5 ffff880214f58fc0 > Call Trace: > [] ? bit_wait+0x50/0x50 > [] schedule+0x35/0x80 > [] schedule_timeout+0x292/0x3d0 > [] ? xen_clocksource_get_cycles+0x15/0x20 > [] ? ktime_get+0x3c/0xb0 > [] ? bit_wait+0x50/0x50 > [] io_schedule_timeout+0xa6/0x110 > [] bit_wait_io+0x1b/0x60 > [] __wait_on_bit+0x64/0x90 > [] wait_on_page_bit+0xc4/0xd0 > [] ? autoremove_wake_function+0x40/0x40 > [] truncate_inode_pages_range+0x409/0x840 > [] ? pcpu_free_area+0x13d/0x1a0 > [] ? wake_up_bit+0x25/0x30 > [] truncate_inode_pages_final+0x4c/0x60 > [] f2fs_evict_inode+0x48/0x390 [f2fs] > [] evict+0xc7/0x1a0 > [] iput+0x197/0x200 > [] f2fs_fill_super+0xab2/0x1130 [f2fs] > [] mount_bdev+0x184/0x1c0 > [] ? f2fs_commit_super+0x100/0x100 [f2fs] > [] f2fs_mount+0x15/0x20 [f2fs] > [] mount_fs+0x39/0x160 > [] vfs_kern_mount+0x67/0x110 > [] do_mount+0x1bb/0xc80 > [] SyS_mount+0x83/0xd0 > [] do_syscall_64+0x6e/0x170 > [] entry_SYSCALL64_slow_path+0x25/0x25 > > Any thoughts? I think this should not happen normally, since f2fs_stop_checkpoint() calls f2fs_flush_merged_bios(). Thanks, > > > > >> > >> Thanks, > >> > >>> > >>> Thanks, > >>> > >>>> + return ret; > >>>> } > >>>> > >>>> int wait_on_node_pages_writeback(struct f2fs_sb_info *sbi, nid_t ino) > >>>> -- > >>>> 2.7.2 > >>> > >>> . > >>> > > > > . > > ------------------------------------------------------------------------------