Re: [f2fs-dev] [PATCH 2/2 v2] f2fs: avoid f2fs_bug_on if f2fs_get_meta_page_nofail got EIO

[Chao Yu]

On 2018/9/19 1:56, Jaegeuk Kim wrote:
> This patch avoids BUG_ON when f2fs_get_meta_page_nofail got EIO during
> xfstests/generic/475.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> ---
> Change log from v1:
>  - propagate errno
>  - drop sum_pages
> 
>  fs/f2fs/checkpoint.c | 10 +++++-----
>  fs/f2fs/f2fs.h       |  2 +-
>  fs/f2fs/gc.c         |  9 +++++++++
>  fs/f2fs/node.c       | 32 ++++++++++++++++++++++++--------
>  fs/f2fs/recovery.c   |  2 ++
>  fs/f2fs/segment.c    |  3 +++
>  6 files changed, 44 insertions(+), 14 deletions(-)
> 
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index 01e0d8f5bbbe..1ddf332ce4b2 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -119,11 +119,8 @@ struct page *f2fs_get_meta_page_nofail(struct f2fs_sb_info *sbi, pgoff_t index)
>  		if (PTR_ERR(page) == -EIO &&
>  				++count <= DEFAULT_RETRY_IO_COUNT)
>  			goto retry;
> -
>  		f2fs_stop_checkpoint(sbi, false);
> -		f2fs_bug_on(sbi, 1);
>  	}
> -
>  	return page;
>  }
>  
> @@ -1512,7 +1509,10 @@ int f2fs_write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>  	ckpt->checkpoint_ver = cpu_to_le64(++ckpt_ver);
>  
>  	/* write cached NAT/SIT entries to NAT/SIT area */
> -	f2fs_flush_nat_entries(sbi, cpc);
> +	err = f2fs_flush_nat_entries(sbi, cpc);
> +	if (err)
> +		goto stop;
> +
>  	f2fs_flush_sit_entries(sbi, cpc);
>  
>  	/* unlock all the fs_lock[] in do_checkpoint() */
> @@ -1521,7 +1521,7 @@ int f2fs_write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>  		f2fs_release_discard_addrs(sbi);
>  	else
>  		f2fs_clear_prefree_segments(sbi, cpc);
> -
> +stop:
>  	unblock_operations(sbi);
>  	stat_inc_cp_count(sbi->stat_info);
>  
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index a0c868127a7c..29021dbc8f2a 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -2895,7 +2895,7 @@ int f2fs_recover_xattr_data(struct inode *inode, struct page *page);
>  int f2fs_recover_inode_page(struct f2fs_sb_info *sbi, struct page *page);
>  int f2fs_restore_node_summary(struct f2fs_sb_info *sbi,
>  			unsigned int segno, struct f2fs_summary_block *sum);
> -void f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc);
> +int f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc);
>  int f2fs_build_node_manager(struct f2fs_sb_info *sbi);
>  void f2fs_destroy_node_manager(struct f2fs_sb_info *sbi);
>  int __init f2fs_create_node_manager_caches(void);
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 4bcc8a59fdef..c7d14282dbf4 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -1070,6 +1070,15 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>  	/* reference all summary page */
>  	while (segno < end_segno) {
>  		sum_page = f2fs_get_sum_page(sbi, segno++);
> +		if (IS_ERR(sum_page)) {
> +			end_segno = segno - 1;
> +			for (segno = start_segno; segno < end_segno; segno++) {
> +				sum_page = find_get_page(META_MAPPING(sbi),
> +						GET_SUM_BLOCK(sbi, segno));
> +				f2fs_put_page(sum_page, 0);
> +			}
> +			return PTR_ERR(sum_page);
> +		}
>  		unlock_page(sum_page);
>  	}
>  
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index fa2381c0bc47..79b6fee354f7 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -126,6 +126,8 @@ static struct page *get_next_nat_page(struct f2fs_sb_info *sbi, nid_t nid)
>  
>  	/* get current nat block page with lock */
>  	src_page = get_current_nat_page(sbi, nid);
> +	if (IS_ERR(src_page))
> +		return src_page;
>  	dst_page = f2fs_grab_meta_page(sbi, dst_off);
>  	f2fs_bug_on(sbi, PageDirty(src_page));
>  
> @@ -2265,15 +2267,19 @@ static int __f2fs_build_free_nids(struct f2fs_sb_info *sbi,
>  						nm_i->nat_block_bitmap)) {
>  			struct page *page = get_current_nat_page(sbi, nid);
>  
> -			ret = scan_nat_page(sbi, page, nid);
> -			f2fs_put_page(page, 1);
> +			if (IS_ERR(page)) {
> +				ret = PTR_ERR(page);
> +			} else {
> +				ret = scan_nat_page(sbi, page, nid);
> +				f2fs_put_page(page, 1);
> +			}
>  
>  			if (ret) {
>  				up_read(&nm_i->nat_tree_lock);
>  				f2fs_bug_on(sbi, !mount);
>  				f2fs_msg(sbi->sb, KERN_ERR,
>  					"NAT is corrupt, run fsck to fix it");
> -				return -EINVAL;
> +				return ret;
>  			}

I mean we can propagate the error to caller of f2fs_alloc_nid(), otherwise
we may loop forever in f2fs_alloc_nid() if we fail to load meta page.

f2fs_alloc_nid()

	err = f2fs_build_free_nids();
	if (err)
		return false;
	goto retry;

Thanks,

>  		}
>  
> @@ -2700,7 +2706,7 @@ static void __update_nat_bits(struct f2fs_sb_info *sbi, nid_t start_nid,
>  		__clear_bit_le(nat_index, nm_i->full_nat_bits);
>  }
>  
> -static void __flush_nat_entry_set(struct f2fs_sb_info *sbi,
> +static int __flush_nat_entry_set(struct f2fs_sb_info *sbi,
>  		struct nat_entry_set *set, struct cp_control *cpc)
>  {
>  	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
> @@ -2724,6 +2730,9 @@ static void __flush_nat_entry_set(struct f2fs_sb_info *sbi,
>  		down_write(&curseg->journal_rwsem);
>  	} else {
>  		page = get_next_nat_page(sbi, start_nid);
> +		if (IS_ERR(page))
> +			return PTR_ERR(page);
> +
>  		nat_blk = page_address(page);
>  		f2fs_bug_on(sbi, !nat_blk);
>  	}
> @@ -2769,12 +2778,13 @@ static void __flush_nat_entry_set(struct f2fs_sb_info *sbi,
>  		radix_tree_delete(&NM_I(sbi)->nat_set_root, set->set);
>  		kmem_cache_free(nat_entry_set_slab, set);
>  	}
> +	return 0;
>  }
>  
>  /*
>   * This function is called during the checkpointing process.
>   */
> -void f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> +int f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>  {
>  	struct f2fs_nm_info *nm_i = NM_I(sbi);
>  	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
> @@ -2784,6 +2794,7 @@ void f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>  	unsigned int found;
>  	nid_t set_idx = 0;
>  	LIST_HEAD(sets);
> +	int err = 0;
>  
>  	/* during unmount, let's flush nat_bits before checking dirty_nat_cnt */
>  	if (enabled_nat_bits(sbi, cpc)) {
> @@ -2793,7 +2804,7 @@ void f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>  	}
>  
>  	if (!nm_i->dirty_nat_cnt)
> -		return;
> +		return 0;
>  
>  	down_write(&nm_i->nat_tree_lock);
>  
> @@ -2816,11 +2827,16 @@ void f2fs_flush_nat_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>  	}
>  
>  	/* flush dirty nats in nat entry set */
> -	list_for_each_entry_safe(set, tmp, &sets, set_list)
> -		__flush_nat_entry_set(sbi, set, cpc);
> +	list_for_each_entry_safe(set, tmp, &sets, set_list) {
> +		err = __flush_nat_entry_set(sbi, set, cpc);
> +		if (err)
> +			break;
> +	}
>  
>  	up_write(&nm_i->nat_tree_lock);
>  	/* Allow dirty nats by node block allocation in write_begin */
> +
> +	return err;
>  }
>  
>  static int __get_nat_bitmaps(struct f2fs_sb_info *sbi)
> diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
> index 56d34193a74b..ba678efe7cad 100644
> --- a/fs/f2fs/recovery.c
> +++ b/fs/f2fs/recovery.c
> @@ -355,6 +355,8 @@ static int check_index_in_prev_nodes(struct f2fs_sb_info *sbi,
>  	}
>  
>  	sum_page = f2fs_get_sum_page(sbi, segno);
> +	if (IS_ERR(sum_page))
> +		return PTR_ERR(sum_page);
>  	sum_node = (struct f2fs_summary_block *)page_address(sum_page);
>  	sum = sum_node->entries[blkoff];
>  	f2fs_put_page(sum_page, 1);
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index aa96a371aaf8..ab7386a7e9d3 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -2487,6 +2487,7 @@ static void change_curseg(struct f2fs_sb_info *sbi, int type)
>  	__next_free_blkoff(sbi, curseg, 0);
>  
>  	sum_page = f2fs_get_sum_page(sbi, new_segno);
> +	f2fs_bug_on(sbi, IS_ERR(sum_page));
>  	sum_node = (struct f2fs_summary_block *)page_address(sum_page);
>  	memcpy(curseg->sum_blk, sum_node, SUM_ENTRY_SIZE);
>  	f2fs_put_page(sum_page, 1);
> @@ -3971,6 +3972,8 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
>  
>  			se = &sit_i->sentries[start];
>  			page = get_current_sit_page(sbi, start);
> +			if (IS_ERR(page))
> +				return PTR_ERR(page);
>  			sit_blk = (struct f2fs_sit_block *)page_address(page);
>  			sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
>  			f2fs_put_page(page, 1);
>