Re: [PATCH v3 05/12] filesystem-dax: Set page->index

[Jan Kara <jack@suse.cz>]

On Mon 04-06-18 16:12:06, Dan Williams wrote:
> In support of enabling memory_failure() handling for filesystem-dax
> mappings, set ->index to the pgoff of the page. The rmap implementation
> requires ->index to bound the search through the vma interval tree. The
> index is set and cleared at dax_associate_entry() and
> dax_disassociate_entry() time respectively.
> 
> Cc: Jan Kara <jack@suse.cz>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Matthew Wilcox <mawilcox@microsoft.com>
> Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Looks good to me. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/dax.c |   16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index aaec72ded1b6..cccf6cad1a7a 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -319,18 +319,27 @@ static unsigned long dax_radix_end_pfn(void *entry)
>  	for (pfn = dax_radix_pfn(entry); \
>  			pfn < dax_radix_end_pfn(entry); pfn++)
>  
> -static void dax_associate_entry(void *entry, struct address_space *mapping)
> +/*
> + * TODO: for reflink+dax we need a way to associate a single page with
> + * multiple address_space instances at different linear_page_index()
> + * offsets.
> + */
> +static void dax_associate_entry(void *entry, struct address_space *mapping,
> +		struct vm_area_struct *vma, unsigned long address)
>  {
> -	unsigned long pfn;
> +	unsigned long size = dax_entry_size(entry), pfn, index;
> +	int i = 0;
>  
>  	if (IS_ENABLED(CONFIG_FS_DAX_LIMITED))
>  		return;
>  
> +	index = linear_page_index(vma, address & ~(size - 1));
>  	for_each_mapped_pfn(entry, pfn) {
>  		struct page *page = pfn_to_page(pfn);
>  
>  		WARN_ON_ONCE(page->mapping);
>  		page->mapping = mapping;
> +		page->index = index + i++;
>  	}
>  }
>  
> @@ -348,6 +357,7 @@ static void dax_disassociate_entry(void *entry, struct address_space *mapping,
>  		WARN_ON_ONCE(trunc && page_ref_count(page) > 1);
>  		WARN_ON_ONCE(page->mapping && page->mapping != mapping);
>  		page->mapping = NULL;
> +		page->index = 0;
>  	}
>  }
>  
> @@ -604,7 +614,7 @@ static void *dax_insert_mapping_entry(struct address_space *mapping,
>  	new_entry = dax_radix_locked_entry(pfn, flags);
>  	if (dax_entry_size(entry) != dax_entry_size(new_entry)) {
>  		dax_disassociate_entry(entry, mapping, false);
> -		dax_associate_entry(new_entry, mapping);
> +		dax_associate_entry(new_entry, mapping, vmf->vma, vmf->address);
>  	}
>  
>  	if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR