Re: [PATCH 14/20] ext4: get rid of ppath in ext4_split_extent()

[Jan Kara]

On Wed 10-07-24 12:06:48, libaokun@xxxxxxxxxxxxxxx wrote:
> From: Baokun Li <libaokun1@xxxxxxxxxx>
> 
> The use of path and ppath is now very confusing, so to make the code more
> readable, pass path between functions uniformly, and get rid of ppath.
> 
> To get rid of the ppath in ext4_split_extent(), the following is done here:
> 
>  * The 'allocated' is changed from passing a value to passing an address.
>  * Its caller needs to update ppath if it uses ppath.
> 
> No functional changes.
> 
> Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

								Honza

> ---
>  fs/ext4/extents.c | 97 ++++++++++++++++++++++++-----------------------
>  1 file changed, 50 insertions(+), 47 deletions(-)
> 
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 0bd068ed324f..2a4f6c89858c 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -3345,21 +3345,18 @@ static struct ext4_ext_path *ext4_split_extent_at(handle_t *handle,
>   *   c> Splits in three extents: Somone is splitting in middle of the extent
>   *
>   */
> -static int ext4_split_extent(handle_t *handle,
> -			      struct inode *inode,
> -			      struct ext4_ext_path **ppath,
> -			      struct ext4_map_blocks *map,
> -			      int split_flag,
> -			      int flags)
> +static struct ext4_ext_path *ext4_split_extent(handle_t *handle,
> +					       struct inode *inode,
> +					       struct ext4_ext_path *path,
> +					       struct ext4_map_blocks *map,
> +					       int split_flag, int flags,
> +					       unsigned int *allocated)
>  {
> -	struct ext4_ext_path *path = *ppath;
>  	ext4_lblk_t ee_block;
>  	struct ext4_extent *ex;
>  	unsigned int ee_len, depth;
> -	int err = 0;
>  	int unwritten;
>  	int split_flag1, flags1;
> -	int allocated = map->m_len;
>  
>  	depth = ext_depth(inode);
>  	ex = path[depth].p_ext;
> @@ -3377,33 +3374,25 @@ static int ext4_split_extent(handle_t *handle,
>  			split_flag1 |= EXT4_EXT_DATA_VALID1;
>  		path = ext4_split_extent_at(handle, inode, path,
>  				map->m_lblk + map->m_len, split_flag1, flags1);
> -		if (IS_ERR(path)) {
> -			err = PTR_ERR(path);
> -			*ppath = NULL;
> -			goto out;
> +		if (IS_ERR(path))
> +			return path;
> +		/*
> +		 * Update path is required because previous ext4_split_extent_at
> +		 * may result in split of original leaf or extent zeroout.
> +		 */
> +		path = ext4_find_extent(inode, map->m_lblk, path, flags);
> +		if (IS_ERR(path))
> +			return path;
> +		depth = ext_depth(inode);
> +		ex = path[depth].p_ext;
> +		if (!ex) {
> +			EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
> +					(unsigned long) map->m_lblk);
> +			ext4_free_ext_path(path);
> +			return ERR_PTR(-EFSCORRUPTED);
>  		}
> -		*ppath = path;
> -	} else {
> -		allocated = ee_len - (map->m_lblk - ee_block);
> -	}
> -	/*
> -	 * Update path is required because previous ext4_split_extent_at() may
> -	 * result in split of original leaf or extent zeroout.
> -	 */
> -	path = ext4_find_extent(inode, map->m_lblk, path, flags);
> -	if (IS_ERR(path)) {
> -		*ppath = NULL;
> -		return PTR_ERR(path);
> -	}
> -	*ppath = path;
> -	depth = ext_depth(inode);
> -	ex = path[depth].p_ext;
> -	if (!ex) {
> -		EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
> -				 (unsigned long) map->m_lblk);
> -		return -EFSCORRUPTED;
> +		unwritten = ext4_ext_is_unwritten(ex);
>  	}
> -	unwritten = ext4_ext_is_unwritten(ex);
>  
>  	if (map->m_lblk >= ee_block) {
>  		split_flag1 = split_flag & EXT4_EXT_DATA_VALID2;
> @@ -3414,17 +3403,18 @@ static int ext4_split_extent(handle_t *handle,
>  		}
>  		path = ext4_split_extent_at(handle, inode, path,
>  				map->m_lblk, split_flag1, flags);
> -		if (IS_ERR(path)) {
> -			err = PTR_ERR(path);
> -			*ppath = NULL;
> -			goto out;
> -		}
> -		*ppath = path;
> +		if (IS_ERR(path))
> +			return path;
>  	}
>  
> +	if (allocated) {
> +		if (map->m_lblk + map->m_len > ee_block + ee_len)
> +			*allocated = ee_len - (map->m_lblk - ee_block);
> +		else
> +			*allocated = map->m_len;
> +	}
>  	ext4_ext_show_leaf(inode, path);
> -out:
> -	return err ? err : allocated;
> +	return path;
>  }
>  
>  /*
> @@ -3669,10 +3659,15 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
>  	}
>  
>  fallback:
> -	err = ext4_split_extent(handle, inode, ppath, &split_map, split_flag,
> -				flags);
> -	if (err > 0)
> -		err = 0;
> +	path = ext4_split_extent(handle, inode, path, &split_map, split_flag,
> +				 flags, NULL);
> +	if (IS_ERR(path)) {
> +		err = PTR_ERR(path);
> +		*ppath = NULL;
> +		goto out;
> +	}
> +	err = 0;
> +	*ppath = path;
>  out:
>  	/* If we have gotten a failure, don't zero out status tree */
>  	if (!err) {
> @@ -3718,6 +3713,7 @@ static int ext4_split_convert_extents(handle_t *handle,
>  	struct ext4_extent *ex;
>  	unsigned int ee_len;
>  	int split_flag = 0, depth;
> +	unsigned int allocated = 0;
>  
>  	ext_debug(inode, "logical block %llu, max_blocks %u\n",
>  		  (unsigned long long)map->m_lblk, map->m_len);
> @@ -3745,7 +3741,14 @@ static int ext4_split_convert_extents(handle_t *handle,
>  		split_flag |= (EXT4_EXT_MARK_UNWRIT2 | EXT4_EXT_DATA_VALID2);
>  	}
>  	flags |= EXT4_GET_BLOCKS_PRE_IO;
> -	return ext4_split_extent(handle, inode, ppath, map, split_flag, flags);
> +	path = ext4_split_extent(handle, inode, path, map, split_flag, flags,
> +				 &allocated);
> +	if (IS_ERR(path)) {
> +		*ppath = NULL;
> +		return PTR_ERR(path);
> +	}
> +	*ppath = path;
> +	return allocated;
>  }
>  
>  static int ext4_convert_unwritten_extents_endio(handle_t *handle,
> -- 
> 2.39.2
> 
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR