Re: [PATCH v2] ext4: add WARN_ON to check the length of allocated blocks

[Zheng Liu <gnehzuil.liu@gmail.com>]

On Fri, Jul 12, 2013 at 09:00:52AM +0800, Zheng Liu wrote:
> From: Zheng Liu <wenqing.lz@taobao.com>
> 
> In this commit (921f266b) a sanity check is added in map_blocks to make
> sure 'retval == map->m_len'.  But we'd better enable this check all the
> time because it can help us to dig some bugs that is hard to be hitted.
> 
> Cc: "Theodore Ts'o" <tytso@mit.edu>
> Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>

Any comment?

Thanks
                                                - Zheng

> ---
> changelog:
> v2 <- v1:
>  * print more details to help us to dig some bugs that is hard to be hitted
> 
> v1: http://patchwork.ozlabs.org/patch/230406/
> 
> Hi Ted,
> 
> This patch sleeps on my own tree for a very long time so that I almost forgot
> it.  Sorry about that.
> 
> 						- Zheng
> 
>  fs/ext4/inode.c |   39 ++++++++++++++++++---------------------
>  1 file changed, 18 insertions(+), 21 deletions(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 19a1643..95bad70 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -556,14 +556,13 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
>  		int ret;
>  		unsigned long long status;
>  
> -#ifdef ES_AGGRESSIVE_TEST
> -		if (retval != map->m_len) {
> -			printk("ES len assertation failed for inode: %lu "
> -			       "retval %d != map->m_len %d "
> -			       "in %s (lookup)\n", inode->i_ino, retval,
> -			       map->m_len, __func__);
> +		if (unlikely(retval != map->m_len)) {
> +			ext4_warning(inode->i_sb,
> +				     "ES len assertation failed for inode: "
> +				     "%lu retval %d != map->m_len %d\n",
> +				     inode->i_ino, retval, map->m_len);
> +			WARN_ON(1);
>  		}
> -#endif
>  
>  		status = map->m_flags & EXT4_MAP_UNWRITTEN ?
>  				EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
> @@ -657,14 +656,13 @@ found:
>  		int ret;
>  		unsigned long long status;
>  
> -#ifdef ES_AGGRESSIVE_TEST
> -		if (retval != map->m_len) {
> -			printk("ES len assertation failed for inode: %lu "
> -			       "retval %d != map->m_len %d "
> -			       "in %s (allocation)\n", inode->i_ino, retval,
> -			       map->m_len, __func__);
> +		if (unlikely(retval != map->m_len)) {
> +			ext4_warning(inode->i_sb,
> +				     "ES len assertation failed for inode: "
> +				     "%lu retval %d != map->m_len %d\n",
> +				     inode->i_ino, retval, map->m_len);
> +			WARN_ON(1);
>  		}
> -#endif
>  
>  		/*
>  		 * If the extent has been zeroed out, we don't need to update
> @@ -1640,14 +1638,13 @@ add_delayed:
>  		int ret;
>  		unsigned long long status;
>  
> -#ifdef ES_AGGRESSIVE_TEST
> -		if (retval != map->m_len) {
> -			printk("ES len assertation failed for inode: %lu "
> -			       "retval %d != map->m_len %d "
> -			       "in %s (lookup)\n", inode->i_ino, retval,
> -			       map->m_len, __func__);
> +		if (unlikely(retval != map->m_len)) {
> +			ext4_warning(inode->i_sb,
> +				     "ES len assertation failed for inode: "
> +				     "%lu retval %d != map->m_len %d\n",
> +				     inode->i_ino, retval, map->m_len);
> +			WARN_ON(1);
>  		}
> -#endif
>  
>  		status = map->m_flags & EXT4_MAP_UNWRITTEN ?
>  				EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
> -- 
> 1.7.9.7
>