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Date:   Tue, 3 Aug 2021 11:26:09 -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, Chao Yu <chao.yu@linux.dev>
Subject: Re: [PATCH] f2fs: compress: do sanity check on cluster
Message-ID: <YQmKQVxQwJL2GU09@google.com>
References: <20210803103952.737222-1-chao@kernel.org>
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On 08/03, Chao Yu wrote:
> This patch adds f2fs_sanity_check_cluster() to support doing
> sanity check on cluster of compressed file, it will be triggered
> from below two paths:
> 
> - __f2fs_cluster_blocks()
> - f2fs_map_blocks(F2FS_GET_BLOCK_FIEMAP)
> 
> And it can detect below three kind of cluster insanity status.
> 
> C: COMPRESS_ADDR
> N: NULL_ADDR or NEW_ADDR
> V: valid blkaddr
> *: any value
> 
> 1. [*|C|*|*]
> 2. [C|*|C|*]
> 3. [C|N|N|V]
> 
> Signed-off-by: Chao Yu <chao@kernel.org>
> ---
>  fs/f2fs/compress.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++
>  fs/f2fs/data.c     | 21 ++++++++++++------
>  fs/f2fs/f2fs.h     |  1 +
>  3 files changed, 68 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
> index 455561826c7d..4aa166d3d9bf 100644
> --- a/fs/f2fs/compress.c
> +++ b/fs/f2fs/compress.c
> @@ -898,6 +898,54 @@ static bool cluster_has_invalid_data(struct compress_ctx *cc)
>  	return false;
>  }
>  
> +bool f2fs_sanity_check_cluster(struct dnode_of_data *dn)
> +{
> +	struct f2fs_sb_info *sbi = F2FS_I_SB(dn->inode);
> +	unsigned int cluster_size = F2FS_I(dn->inode)->i_cluster_size;
> +	bool compressed = dn->data_blkaddr == COMPRESS_ADDR;
> +	int cluster_end = 0;
> +	int i;
> +	char *reason = "";
> +
> +	if (!compressed)
> +		return false;
> +
> +	/* [..., COMPR_ADDR, ...] */
> +	if (dn->ofs_in_node % cluster_size) {
> +		reason = "[*|C|*|*]";
> +		goto out;
> +	}
> +
> +	for (i = 1; i < cluster_size; i++) {
> +		block_t blkaddr = data_blkaddr(dn->inode, dn->node_page,
> +							dn->ofs_in_node + i);
> +
> +		/* [COMPR_ADDR, ..., COMPR_ADDR] */
> +		if (blkaddr == COMPRESS_ADDR) {
> +			reason = "[C|*|C|*]";
> +			goto out;
> +		}
> +		if (compressed) {
> +			if (!__is_valid_data_blkaddr(blkaddr)) {
> +				if (!cluster_end)
> +					cluster_end = i;
> +				continue;
> +			}
> +			/* [COMPR_ADDR, NULL_ADDR or NEW_ADDR, valid_blkaddr] */
> +			if (cluster_end) {
> +				reason = "[C|N|N|V]";
> +				goto out;
> +			}
> +		}
> +	}
> +	return false;
> +out:
> +	f2fs_warn(sbi, "access invalid cluster, ino:%lu, nid:%u, ofs_in_node:%u, reason:%s",
> +			dn->inode->i_ino, dn->nid, dn->ofs_in_node, reason);
> +	set_sbi_flag(sbi, SBI_NEED_FSCK);
> +	return true;
> +}
> +
>  static int __f2fs_cluster_blocks(struct inode *inode,
>  				unsigned int cluster_idx, bool compr)
>  {
> @@ -915,6 +963,11 @@ static int __f2fs_cluster_blocks(struct inode *inode,
>  		goto fail;
>  	}
>  
> +	if (f2fs_sanity_check_cluster(&dn)) {
> +		ret = -EFSCORRUPTED;
> +		goto fail;
> +	}
> +
>  	if (dn.data_blkaddr == COMPRESS_ADDR) {
>  		int i;
>  
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 948083c88d17..75dda2035f68 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -1558,13 +1558,20 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
>  			}
>  			if (flag == F2FS_GET_BLOCK_PRECACHE)
>  				goto sync_out;
> -			if (flag == F2FS_GET_BLOCK_FIEMAP &&
> -						blkaddr == NULL_ADDR) {
> -				if (map->m_next_pgofs)
> -					*map->m_next_pgofs = pgofs + 1;
> -				goto sync_out;
> -			}
> -			if (flag != F2FS_GET_BLOCK_FIEMAP) {
> +			if (flag == F2FS_GET_BLOCK_FIEMAP) {
> +				if (blkaddr == NULL_ADDR) {
> +					if (map->m_next_pgofs)
> +						*map->m_next_pgofs = pgofs + 1;
> +					goto sync_out;
> +				}
> +#ifdef CONFIG_F2FS_FS_COMPRESSION
> +				if (f2fs_compressed_file(inode) &&
> +					f2fs_sanity_check_cluster(&dn)) {
> +					err = -EFSCORRUPTED;

I prefer to give the block map as is instead of giving an error, since this
takes away to debug the problem from user-land.

> +					goto sync_out;
> +				}
> +#endif
> +			} else {
>  				/* for defragment case */
>  				if (map->m_next_pgofs)
>  					*map->m_next_pgofs = pgofs + 1;
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 20389b9b3eac..86d416ffad61 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -4060,6 +4060,7 @@ void f2fs_end_read_compressed_page(struct page *page, bool failed,
>  							block_t blkaddr);
>  bool f2fs_cluster_is_empty(struct compress_ctx *cc);
>  bool f2fs_cluster_can_merge_page(struct compress_ctx *cc, pgoff_t index);
> +bool f2fs_sanity_check_cluster(struct dnode_of_data *dn);
>  void f2fs_compress_ctx_add_page(struct compress_ctx *cc, struct page *page);
>  int f2fs_write_multi_pages(struct compress_ctx *cc,
>  						int *submitted,
> -- 
> 2.22.1