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Date:   Wed, 12 Dec 2018 08:47:49 +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: <20181212031749.GF9838@codeaurora.org>
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On Fri, Dec 07, 2018 at 05:47:31PM +0800, Chao Yu wrote:
> On 2018/12/1 4:33, Jaegeuk Kim wrote:
> > On 11/29, Sahitya Tummala wrote:
> >>
> >> On Tue, Nov 27, 2018 at 09:42:39AM +0800, Chao Yu wrote:
> >>> On 2018/11/27 8:30, Jaegeuk Kim wrote:
> >>>> On 11/26, 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.
> >>>>>
> >>>>> Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
> >>>>> ---
> >>>>> v2:
> >>>>> -call evict_inodes() and f2fs_shrink_extent_tree() to cleanup inodes
> >>>>>
> >>>>>  fs/f2fs/f2fs.h     |  1 +
> >>>>>  fs/f2fs/shrinker.c |  2 +-
> >>>>>  fs/f2fs/super.c    | 13 ++++++++++++-
> >>>>>  3 files changed, 14 insertions(+), 2 deletions(-)
> >>>>>
> >>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> >>>>> index 1e03197..aaee63b 100644
> >>>>> --- a/fs/f2fs/f2fs.h
> >>>>> +++ b/fs/f2fs/f2fs.h
> >>>>> @@ -3407,6 +3407,7 @@ struct rb_entry *f2fs_lookup_rb_tree_ret(struct rb_root_cached *root,
> >>>>>  bool f2fs_check_rb_tree_consistence(struct f2fs_sb_info *sbi,
> >>>>>  						struct rb_root_cached *root);
> >>>>>  unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink);
> >>>>> +unsigned long __count_extent_cache(struct f2fs_sb_info *sbi);
> >>>>>  bool f2fs_init_extent_tree(struct inode *inode, struct f2fs_extent *i_ext);
> >>>>>  void f2fs_drop_extent_tree(struct inode *inode);
> >>>>>  unsigned int f2fs_destroy_extent_node(struct inode *inode);
> >>>>> diff --git a/fs/f2fs/shrinker.c b/fs/f2fs/shrinker.c
> >>>>> index 9e13db9..7e3c13b 100644
> >>>>> --- a/fs/f2fs/shrinker.c
> >>>>> +++ b/fs/f2fs/shrinker.c
> >>>>> @@ -30,7 +30,7 @@ static unsigned long __count_free_nids(struct f2fs_sb_info *sbi)
> >>>>>  	return count > 0 ? count : 0;
> >>>>>  }
> >>>>>  
> >>>>> -static unsigned long __count_extent_cache(struct f2fs_sb_info *sbi)
> >>>>> +unsigned long __count_extent_cache(struct f2fs_sb_info *sbi)
> >>>>>  {
> >>>>>  	return atomic_read(&sbi->total_zombie_tree) +
> >>>>>  				atomic_read(&sbi->total_ext_node);
> >>>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> >>>>> index af58b2c..769e7b1 100644
> >>>>> --- a/fs/f2fs/super.c
> >>>>> +++ b/fs/f2fs/super.c
> >>>>> @@ -3016,6 +3016,16 @@ static void f2fs_tuning_parameters(struct f2fs_sb_info *sbi)
> >>>>>  	sbi->readdir_ra = 1;
> >>>>>  }
> >>>>>  
> >>>>> +static void f2fs_cleanup_inodes(struct f2fs_sb_info *sbi)
> >>>>> +{
> >>>>> +	struct super_block *sb = sbi->sb;
> >>>>> +
> >>>>> +	sync_filesystem(sb);
> >>>>
> >>>> This writes another checkpoint, which would not be what this retrial intended.
> >>>
> >>> Actually, checkpoint will not be triggered due to SBI_POR_DOING flag check
> >>> as below:
> >>>
> >>> int f2fs_sync_fs(struct super_block *sb, int sync)
> >>> {
> >>> ...
> >>> 	if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
> >>> 		return -EAGAIN;
> >>> ...
> >>> }
> >>>
> >>> And also all dirty data/node won't be persisted due to SBI_POR_DOING flag,
> >>> IIUC.
> >>>
> >>
> >> Thanks Chao for the clarification.
> >>
> >> Hi Jaegeuk,
> >>
> >> Do you still have any further concerns or comments on this patch?
> > 
> > Could you try the below first?
> > 
> > --  How about adding a condition in f2fs_may_extent_tree() when adding extents?
> > -- Likewise, if (shrinker is not registered) return false;
> > 
> > If we can fix what you described directly, I don't want to rely on such the
> > assumptions saying we won't do checkpoint. This flow literally says syncing
> > and evicting cached objects, which opposed to what we'd like to drop all caches
> > and restart fill_super again.
> > 
> > Let me consider this as a final resolution.
> 
> Jaegeuk,
> 
> Still I want to ask, what kind of scenario we have to add retry logic in
> fill_super for? As in android scenario, it must be extreme rare case that
> system runs out-of-memory in boot time...at least, I didn't get any kind of
> report like that.
> 
Hi Chao,

In my case, the first boot up has a failure in recovery as below -

F2FS-fs (mmcblk0p75): find_fsync_dnodes: detect looped node chain, blkaddr:1979471, next:1979472
F2FS-fs (mmcblk0p75): Cannot recover all fsync data errno=-22

But in the second attempt, retry will be set to false and because of that
recover_fsync_data() is skipped. This helped mount to be successful in
the second attempt. 

Thanks,

> Thanks,
> 
> > 
> > Thanks,
> > 
> >>
> >> Thanks,
> >> Sahitya.
> >>
> >>> Thanks,
> >>>
> >>>> How about adding a condition in f2fs_may_extent_tree() when adding extents?
> >>>> Likewise, if (shrinker is not registered) return false;
> >>>>
> >>>>
> >>>>> +	shrink_dcache_sb(sb);
> >>>>> +	evict_inodes(sb);
> >>>>> +	f2fs_shrink_extent_tree(sbi, __count_extent_cache(sbi));
> >>>>> +}
> >>>>> +
> >>>>>  static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
> >>>>>  {
> >>>>>  	struct f2fs_sb_info *sbi;
> >>>>> @@ -3402,6 +3412,8 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
> >>>>>  	 * falls into an infinite loop in f2fs_sync_meta_pages().
> >>>>>  	 */
> >>>>>  	truncate_inode_pages_final(META_MAPPING(sbi));
> >>>>> +	/* cleanup recovery and quota inodes */
> >>>>> +	f2fs_cleanup_inodes(sbi);
> >>>>>  	f2fs_unregister_sysfs(sbi);
> >>>>>  free_root_inode:
> >>>>>  	dput(sb->s_root);
> >>>>> @@ -3445,7 +3457,6 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
> >>>>>  	/* give only one another chance */
> >>>>>  	if (retry) {
> >>>>>  		retry = false;
> >>>>> -		shrink_dcache_sb(sb);
> >>>>>  		goto try_onemore;
> >>>>>  	}
> >>>>>  	return err;
> >>>>> -- 
> >>>>> Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.
> >>>>> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.
> >>>>
> >>>> .
> >>>>
> >>>
> >>
> >> -- 
> >> --
> >> Sent by a consultant of the Qualcomm Innovation Center, Inc.
> >> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
> > 
> > .
> > 
> 

-- 
--
Sent by a consultant of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.