Re: [PATCH v2] f2fs: fix sbi->extent_list corruption issue

[Sahitya Tummala]

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@xxxxxxxxxxxxxx>
> >> ---
> >> 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?

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.
> > 
> > .
> > 
> 

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