[PATCH v7 2/4] xfs: Introduce a helper routine to probe data or hole offset from page cache

[Mark Tinguely]

On 08/13/12 08:07, Jeff Liu wrote:
> helper routine to lookup data or hole offset from page cache for unwritten extents.
>
> Signed-off-by: Jie Liu<jeff.liu at oracle.com>
>
> ---
>   fs/xfs/xfs_file.c |  213 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>   1 files changed, 213 insertions(+), 0 deletions(-)
> +STATIC bool
> +xfs_find_get_desired_pgoff(
> +	struct inode		*inode,
> +	struct xfs_bmbt_irec	*map,
> +	unsigned int		type,
> +	loff_t			*offset)
> +{

...

> +		for (i = 0; i<  nr_pages; i++) {
> +			struct page	*page = pvec.pages[i];
> +			loff_t		b_offset;
> +
> +			/*
> +			 * Page index is out of range, searching done.
> +			 * If the current offset is not reaches the end
> +			 * of the specified search range, there should
> +			 * be a hole between them.
> +			 */
> +			if (page->index>  end) {

Shouldn't this sample of the index also be locked?

> +				if (type == HOLE_OFF&&  lastoff<  endoff) {
> +					*offset = lastoff;
> +					found = true;
> +				}
> +				goto out;
> +			}
> +
> +			lock_page(page);

--Mark.