Re: [RFC PATCH v4 27/34] ext4: implement zero_range iomap path

Dave Chinner
2024-05-01T09:40:10Z

On Wed, Apr 10, 2024 at 10:29:41PM +0800, Zhang Yi wrote:
> From: Zhang Yi <yi.zhang@huawei.com>
>
> Add ext4_iomap_zero_range() for the zero_range iomap path, it zero out
> the mapped blocks, all work have been done in iomap_zero_range(), so
> call it directly.
>
> Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
> ---
> fs/ext4/inode.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 9d694c780007..5af3b8acf1b9 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4144,6 +4144,13 @@ static int __ext4_block_zero_page_range(handle_t *handle,
> return err;
> }
>
> +static int ext4_iomap_zero_range(struct inode *inode,
> + loff_t from, loff_t length)
> +{
> + return iomap_zero_range(inode, from, length, NULL,
> + &ext4_iomap_buffered_read_ops);
> +}

Zeroing is a buffered write operation, not a buffered read
operation. It runs though iomap_write_begin(), so needs all the
stale iomap detection stuff to be set up for correct operation.

-Dave.
--
Dave Chinner
david@fromorbit.com