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Date:   Mon, 26 Nov 2018 16:30:50 -0800
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Sahitya Tummala <stummala@codeaurora.org>
Cc:     Chao Yu <yuchao0@huawei.com>,
        linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] f2fs: fix sbi->extent_list corruption issue
Message-ID: <20181127003050.GG55960@jaegeuk-macbookpro.roam.corp.google.com>
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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.
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.