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Date:   Thu, 10 Jan 2019 12:09:21 +0530
From:   Sahitya Tummala <stummala@codeaurora.org>
To:     Chao Yu <yuchao0@huawei.com>
Cc:     Jaegeuk Kim <jaegeuk@kernel.org>,
        linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] f2fs: fix sbi->extent_list corruption issue
Message-ID: <20190110063921.GA7308@codeaurora.org>
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On Wed, Jan 09, 2019 at 02:13:02PM +0800, Chao Yu wrote:
> On 2019/1/9 12:38, Jaegeuk Kim wrote:
> > On 01/07, Chao Yu wrote:
> >> On 2019/1/5 4:33, Jaegeuk Kim wrote:
> >>> On 01/04, Sahitya Tummala wrote:
> >>>> On Mon, Nov 26, 2018 at 10:17:20AM +0530, Sahitya Tummala wrote:
> >>>>> When there is a failure in f2fs_fill_super() after/during
> >>>>> the recovery of fsync'd nodes, it frees the current sbi and
> >>>>> retries again. This time the mount is successful, but the files
> >>>>> that got recovered before retry, still holds the extent tree,
> >>>>> whose extent nodes list is corrupted since sbi and sbi->extent_list
> >>>>> is freed up. The list_del corruption issue is observed when the
> >>>>> file system is getting unmounted and when those recoverd files extent
> >>>>> node is being freed up in the below context.
> >>>>>
> >>>>> list_del corruption. prev->next should be fffffff1e1ef5480, but was (null)
> >>>>> <...>
> >>>>> kernel BUG at kernel/msm-4.14/lib/list_debug.c:53!
> >>>>> task: fffffff1f46f2280 task.stack: ffffff8008068000
> >>>>> lr : __list_del_entry_valid+0x94/0xb4
> >>>>> pc : __list_del_entry_valid+0x94/0xb4
> >>>>> <...>
> >>>>> Call trace:
> >>>>> __list_del_entry_valid+0x94/0xb4
> >>>>> __release_extent_node+0xb0/0x114
> >>>>> __free_extent_tree+0x58/0x7c
> >>>>> f2fs_shrink_extent_tree+0xdc/0x3b0
> >>>>> f2fs_leave_shrinker+0x28/0x7c
> >>>>> f2fs_put_super+0xfc/0x1e0
> >>>>> generic_shutdown_super+0x70/0xf4
> >>>>> kill_block_super+0x2c/0x5c
> >>>>> kill_f2fs_super+0x44/0x50
> >>>>> deactivate_locked_super+0x60/0x8c
> >>>>> deactivate_super+0x68/0x74
> >>>>> cleanup_mnt+0x40/0x78
> >>>>> __cleanup_mnt+0x1c/0x28
> >>>>> task_work_run+0x48/0xd0
> >>>>> do_notify_resume+0x678/0xe98
> >>>>> work_pending+0x8/0x14
> >>>>>
> >>>>> Fix this by cleaning up inodes, extent tree and nodes of those
> >>>>> recovered files before freeing up sbi and before next retry.
> >>>>>
> >>>> Hi Jaegeuk, Chao,
> >>>>
> >>>> I have observed another scenario where the similar list corruption issue
> >>>> can happen with sbi->inode_list as well. If recover_fsync_data()
> >>>> fails at some point in write_checkpoint() due to some error and if
> >>>> those recovered inodes are still dirty, then after the mount is
> >>>> successful, this issue is observed when that dirty inode is under 
> >>>> writeback.
> >>>
> >>> recover_fsync_data() does iget/iput in pair, and destroy_fsync_dnodes() drops
> >>> its dirty list and call iput(), when there is an error. So, after then, there'd
> >>> be no dirty inodes. If there's no error, checkpoint() flushes quota/dentry pages
> >>> in dirty inodes as well. Can we check where this dirty inode came from?
> >>
> >> I guess it comes from:
> >>
> >> f2fs_recover_fsync_data()
> >>
> >> 	/* Needed for iput() to work correctly and not trash data */
> >> 	sbi->sb->s_flags |= SB_ACTIVE;
> >>
> >> iput_final()
> >>
> >> 	if (!drop && (sb->s_flags & SB_ACTIVE)) {
> >> 		inode_add_lru(inode);
> >> 		spin_unlock(&inode->i_lock);
> >> 		return;
> >> 	}
> >>
> >> So dirty data in those inode can be remained after iput(), then meta/node
> >> can be persisted during next checkpoint, if checkpoint failed due to error,
> >> dirty inode remain in system. IIUC.
> > 
> > 
> > 749         err = recover_data(sbi, &inode_list, &tmp_inode_list, &dir_list);
> > 750         if (!err)
> > 751                 f2fs_bug_on(sbi, !list_empty(&inode_list));
> > 752         else {
> > 753                 /* restore s_flags to let iput() trash data */
> > 754                 sbi->sb->s_flags = s_flags;
> > 755         }
> > 
> > We deactivate sb before iput?
> 
> We only restore s_flags in error path of recover_data? I remember Sahitya
> said his case is encountering error in later checkpoint()?
> 

Thanks Chao and Jaegeuk for taking a look at this.
I might be wrong earlier on the point of error.
The case that Jaegeuk has addressed below looks good for now.
https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git/commit/?h=dev&id=cd2dcebde8b8088b8ad77184ee3a1e81fd3da6ba

> Thanks,
> 
> > 
> >>
> >>>
> >>> Oh, one sceanrio can be an error by f2fs_disable_checkpoint() which will do GC.
> >>>
> >>>>
> >>>> [   90.400500] list_del corruption. prev->next should be ffffffed1f566208, but was (null)
> >>>> [   90.675349] Call trace:
> >>>> [   90.677869]  __list_del_entry_valid+0x94/0xb4
> >>>> [   90.682351]  remove_dirty_inode+0xac/0x114
> >>>> [   90.686563]  __f2fs_write_data_pages+0x6a8/0x6c8
> >>>> [   90.691302]  f2fs_write_data_pages+0x40/0x4c
> >>>> [   90.695695]  do_writepages+0x80/0xf0
> >>>> [   90.699372]  __writeback_single_inode+0xdc/0x4ac
> >>>> [   90.704113]  writeback_sb_inodes+0x280/0x440
> >>>> [   90.708501]  wb_writeback+0x1b8/0x3d0
> >>>> [   90.712267]  wb_workfn+0x1a8/0x4d4
> >>>> [   90.715765]  process_one_work+0x1c0/0x3d4
> >>>> [   90.719883]  worker_thread+0x224/0x344
> >>>> [   90.723739]  kthread+0x120/0x130
> >>>> [   90.727055]  ret_from_fork+0x10/0x18
> >>>>
> >>>> I think it is better to cleanup those inodes completely before freeing sbi
> >>>> and before next retry as done in this patch. Would you like to re-consider
> >>>> this patch for this new issue?
> >>>
> >>> The patch was merged in mainline already.
> >>> Could you take a look at this patch?
> >>>
> >>> >From cb1d20e640402beed300c2bdce79311ee8a781ad Mon Sep 17 00:00:00 2001
> >>> From: Jaegeuk Kim <jaegeuk@kernel.org>
> >>> Date: Fri, 4 Jan 2019 12:29:00 -0800
> >>> Subject: [PATCH] f2fs: sync filesystem after roll-forward recovery
> >>
> >> You mean android kernel mainline?
> > 
> > I meant the previous patch was upstreamed. We need another patch to address this
> > second issue.
> > 
> > Thanks,
> > 
> >>
> >> Thanks,
> >>
> >>>
> >>> Some works after roll-forward recovery can get an error which will release
> >>> all the data structures. Let's flush them in order to make it clean.
> >>>
> >>> One possible corruption came from:
> >>>
> >>> [   90.400500] list_del corruption. prev->next should be ffffffed1f566208, but was (null)
> >>> [   90.675349] Call trace:
> >>> [   90.677869]  __list_del_entry_valid+0x94/0xb4
> >>> [   90.682351]  remove_dirty_inode+0xac/0x114
> >>> [   90.686563]  __f2fs_write_data_pages+0x6a8/0x6c8
> >>> [   90.691302]  f2fs_write_data_pages+0x40/0x4c
> >>> [   90.695695]  do_writepages+0x80/0xf0
> >>> [   90.699372]  __writeback_single_inode+0xdc/0x4ac
> >>> [   90.704113]  writeback_sb_inodes+0x280/0x440
> >>> [   90.708501]  wb_writeback+0x1b8/0x3d0
> >>> [   90.712267]  wb_workfn+0x1a8/0x4d4
> >>> [   90.715765]  process_one_work+0x1c0/0x3d4
> >>> [   90.719883]  worker_thread+0x224/0x344
> >>> [   90.723739]  kthread+0x120/0x130
> >>> [   90.727055]  ret_from_fork+0x10/0x18
> >>>
> >>> Reported-by: Sahitya Tummala <stummala@codeaurora.org>
> >>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> >>> ---
> >>>  fs/f2fs/super.c | 8 ++++++--
> >>>  1 file changed, 6 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> >>> index 547cb7459be7..bb02186293a3 100644
> >>> --- a/fs/f2fs/super.c
> >>> +++ b/fs/f2fs/super.c
> >>> @@ -3357,7 +3357,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
> >>>  	if (test_opt(sbi, DISABLE_CHECKPOINT)) {
> >>>  		err = f2fs_disable_checkpoint(sbi);
> >>>  		if (err)
> >>> -			goto free_meta;
> >>> +			goto sync_free_meta;
> >>>  	} else if (is_set_ckpt_flags(sbi, CP_DISABLED_FLAG)) {
> >>>  		f2fs_enable_checkpoint(sbi);
> >>>  	}
> >>> @@ -3370,7 +3370,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
> >>>  		/* After POR, we can run background GC thread.*/
> >>>  		err = f2fs_start_gc_thread(sbi);
> >>>  		if (err)
> >>> -			goto free_meta;
> >>> +			goto sync_free_meta;
> >>>  	}
> >>>  	kvfree(options);
> >>>  
> >>> @@ -3392,6 +3392,10 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
> >>>  	f2fs_update_time(sbi, REQ_TIME);
> >>>  	return 0;
> >>>  
> >>> +sync_free_meta:
> >>> +	/* safe to flush all the data */
> >>> +	sync_filesystem(sbi->sb);
> >>> +
> >>>  free_meta:
> >>>  	/* flush dirty orphan inode objects */
> >>>  	f2fs_sync_inode_meta(sbi);
> >>>
> > 
> > .
> > 
> 

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