Re: [PATCH 1/6] ext4: move partial block zeroing earlier in ext4_zero_range()

[Jan Kara]

On Wed 01-07-26 22:20:04, yizhang089@xxxxxxxxx wrote:
> From: Zhang Yi <yi.zhang@xxxxxxxxxx>
> 
> In ext4_zero_range(), move the ext4_zero_partial_blocks() call, which
> handles unaligned edges, into the same branch where the unaligned range
> is preallocated, immediately after ext4_alloc_file_blocks(). This is
> safe because there is no dependency between partial block handling and
> the subsequent full block handling.
> 
> This change will be used by later patches that handle unaligned
> FALLOC_FL_WRITE_ZEROES operations, which will need to check the partial
> zeroed result.
> 
> Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

								Honza

> ---
>  fs/ext4/extents.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 125f628e738a..27ca641e701b 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -4734,10 +4734,16 @@ static long ext4_zero_range(struct file *file, loff_t offset,
>  	}
>  
>  	flags = EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT;
> -	/* Preallocate the range including the unaligned edges */
> +	/*
> +	 * Preallocate the range including the unaligned edges, and zero
> +	 * out partial blocks if they already contain data.
> +	 */
>  	if (!IS_ALIGNED(offset | end, blocksize)) {
>  		ret = ext4_alloc_file_blocks(file, offset, len, new_size,
>  					     flags);
> +		if (!ret)
> +			ret = ext4_zero_partial_blocks(inode, offset, len,
> +						       &partial_zeroed);
>  		if (ret)
>  			return ret;
>  	}
> @@ -4770,10 +4776,6 @@ static long ext4_zero_range(struct file *file, loff_t offset,
>  	if (IS_ALIGNED(offset | end, blocksize))
>  		return ret;
>  
> -	/* Zero out partial block at the edges of the range */
> -	ret = ext4_zero_partial_blocks(inode, offset, len, &partial_zeroed);
> -	if (ret)
> -		return ret;
>  	if (((file->f_flags & O_SYNC) || IS_SYNC(inode)) && partial_zeroed) {
>  		ret = filemap_write_and_wait_range(inode->i_mapping, offset,
>  						   end - 1);
> -- 
> 2.53.0
> 
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR