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Date:   Thu, 5 May 2022 17:53:12 -0700
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Chao Yu <chao@kernel.org>
Cc:     linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Ming Yan <yanming@tju.edu.cn>, Chao Yu <chao.yu@oppo.com>
Subject: Re: [PATCH v2] f2fs: fix to do sanity check on total_data_blocks
Message-ID: <YnRxeJbYNC9eHgtr@google.com>
References: <20220505141507.6616-1-chao@kernel.org>
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On 05/05, Chao Yu wrote:
> As Yanming reported in bugzilla:
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=215916
> 
> The kernel message is shown below:
> 
> kernel BUG at fs/f2fs/segment.c:2560!
> Call Trace:
>  allocate_segment_by_default+0x228/0x440
>  f2fs_allocate_data_block+0x13d1/0x31f0
>  do_write_page+0x18d/0x710
>  f2fs_outplace_write_data+0x151/0x250
>  f2fs_do_write_data_page+0xef9/0x1980
>  move_data_page+0x6af/0xbc0
>  do_garbage_collect+0x312f/0x46f0
>  f2fs_gc+0x6b0/0x3bc0
>  f2fs_balance_fs+0x921/0x2260
>  f2fs_write_single_data_page+0x16be/0x2370
>  f2fs_write_cache_pages+0x428/0xd00
>  f2fs_write_data_pages+0x96e/0xd50
>  do_writepages+0x168/0x550
>  __writeback_single_inode+0x9f/0x870
>  writeback_sb_inodes+0x47d/0xb20
>  __writeback_inodes_wb+0xb2/0x200
>  wb_writeback+0x4bd/0x660
>  wb_workfn+0x5f3/0xab0
>  process_one_work+0x79f/0x13e0
>  worker_thread+0x89/0xf60
>  kthread+0x26a/0x300
>  ret_from_fork+0x22/0x30
> RIP: 0010:new_curseg+0xe8d/0x15f0
> 
> The root cause is: ckpt.valid_block_count is inconsistent with SIT table,
> stat info indicates filesystem has free blocks, but SIT table indicates
> filesystem has no free segment.
> 
> So that during garbage colloection, it triggers panic when LFS allocator
> fails to find free segment.
> 
> This patch tries to fix this issue by checking consistency in between
> ckpt.valid_block_count and block accounted from SIT.
> 
> Cc: stable@vger.kernel.org
> Reported-by: Ming Yan <yanming@tju.edu.cn>
> Signed-off-by: Chao Yu <chao.yu@oppo.com>
> ---
> v2:
> - adjust check condition according to the case Jaegeuk mentioned.
>  fs/f2fs/segment.c | 24 +++++++++++++++++++++---
>  1 file changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 3a3e2cec2ac4..942d6d8c18e6 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -4462,6 +4462,7 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
>  	unsigned int readed, start_blk = 0;
>  	int err = 0;
>  	block_t total_node_blocks = 0;
> +	block_t total_data_blocks = 0;

How about something like "sit_valid_blocks[DATA | NODE]"?

>  
>  	do {
>  		readed = f2fs_ra_meta_pages(sbi, start_blk, BIO_MAX_VECS,
> @@ -4488,6 +4489,8 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
>  			seg_info_from_raw_sit(se, &sit);
>  			if (IS_NODESEG(se->type))
>  				total_node_blocks += se->valid_blocks;
> +			else
> +				total_data_blocks += se->valid_blocks;
>  
>  			if (f2fs_block_unit_discard(sbi)) {
>  				/* build discard map only one time */
> @@ -4529,6 +4532,8 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
>  		old_valid_blocks = se->valid_blocks;
>  		if (IS_NODESEG(se->type))
>  			total_node_blocks -= old_valid_blocks;
> +		else
> +			total_data_blocks -= old_valid_blocks;
>  
>  		err = check_block_count(sbi, start, &sit);
>  		if (err)
> @@ -4536,6 +4541,8 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
>  		seg_info_from_raw_sit(se, &sit);
>  		if (IS_NODESEG(se->type))
>  			total_node_blocks += se->valid_blocks;
> +		else
> +			total_data_blocks += se->valid_blocks;
>  
>  		if (f2fs_block_unit_discard(sbi)) {
>  			if (is_set_ckpt_flags(sbi, CP_TRIMMED_FLAG)) {
> @@ -4557,13 +4564,24 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
>  	}
>  	up_read(&curseg->journal_rwsem);
>  
> -	if (!err && total_node_blocks != valid_node_count(sbi)) {
> +	if (err)
> +		return err;
> +
> +	if (total_node_blocks != valid_node_count(sbi)) {
>  		f2fs_err(sbi, "SIT is corrupted node# %u vs %u",
>  			 total_node_blocks, valid_node_count(sbi));
> -		err = -EFSCORRUPTED;
> +		return -EFSCORRUPTED;
>  	}
>  
> -	return err;
> +	if (total_data_blocks + total_node_blocks >
> +				valid_user_blocks(sbi)) {
> +		f2fs_err(sbi, "SIT is corrupted data# %u %u vs %u",
> +			 total_data_blocks, total_node_blocks,
> +			 valid_user_blocks(sbi));
> +		return -EFSCORRUPTED;
> +	}
> +
> +	return 0;
>  }
>  
>  static void init_free_segmap(struct f2fs_sb_info *sbi)
> -- 
> 2.32.0