Re: [PATCH 13/29] fsdax: use a saner calling convention for copy_cow_page_dax

Dan Williams
2021-11-23T19:36:00Z

On Tue, Nov 9, 2021 at 12:33 AM Christoph Hellwig <hch@lst.de> wrote:
>
> Just pass the vm_fault and iomap_iter structures, and figure out the rest
> locally. Note that this requires moving dax_iomap_sector up in the file.

Looks good,

Reviewed-by: Dan Williams <dan.j.williams@intel.com>

>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> fs/dax.c | 29 +++++++++++++----------------
> 1 file changed, 13 insertions(+), 16 deletions(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index 73bd1439d8089..e51b4129d1b65 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -709,26 +709,31 @@ int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
> return __dax_invalidate_entry(mapping, index, false);
> }
>
> -static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_dev,
> - sector_t sector, struct page *to, unsigned long vaddr)
> +static sector_t dax_iomap_sector(const struct iomap *iomap, loff_t pos)
> {
> + return (iomap->addr + (pos & PAGE_MASK) - iomap->offset) >> 9;
> +}
> +
> +static int copy_cow_page_dax(struct vm_fault *vmf, const struct iomap_iter *iter)
> +{
> + sector_t sector = dax_iomap_sector(&iter->iomap, iter->pos);
> void *vto, *kaddr;
> pgoff_t pgoff;
> long rc;
> int id;
>
> - rc = bdev_dax_pgoff(bdev, sector, PAGE_SIZE, &pgoff);
> + rc = bdev_dax_pgoff(iter->iomap.bdev, sector, PAGE_SIZE, &pgoff);
> if (rc)
> return rc;
>
> id = dax_read_lock();
> - rc = dax_direct_access(dax_dev, pgoff, 1, &kaddr, NULL);
> + rc = dax_direct_access(iter->iomap.dax_dev, pgoff, 1, &kaddr, NULL);
> if (rc < 0) {
> dax_read_unlock(id);
> return rc;
> }
> - vto = kmap_atomic(to);
> - copy_user_page(vto, kaddr, vaddr, to);
> + vto = kmap_atomic(vmf->cow_page);
> + copy_user_page(vto, kaddr, vmf->address, vmf->cow_page);
> kunmap_atomic(vto);
> dax_read_unlock(id);
> return 0;
> @@ -1005,11 +1010,6 @@ int dax_writeback_mapping_range(struct address_space *mapping,
> }
> EXPORT_SYMBOL_GPL(dax_writeback_mapping_range);
>
> -static sector_t dax_iomap_sector(const struct iomap *iomap, loff_t pos)
> -{
> - return (iomap->addr + (pos & PAGE_MASK) - iomap->offset) >> 9;
> -}
> -
> static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size,
> pfn_t *pfnp)
> {
> @@ -1332,19 +1332,16 @@ static vm_fault_t dax_fault_synchronous_pfnp(pfn_t *pfnp, pfn_t pfn)
> static vm_fault_t dax_fault_cow_page(struct vm_fault *vmf,
> const struct iomap_iter *iter)
> {
> - sector_t sector = dax_iomap_sector(&iter->iomap, iter->pos);
> - unsigned long vaddr = vmf->address;
> vm_fault_t ret;
> int error = 0;
>
> switch (iter->iomap.type) {
> case IOMAP_HOLE:
> case IOMAP_UNWRITTEN:
> - clear_user_highpage(vmf->cow_page, vaddr);
> + clear_user_highpage(vmf->cow_page, vmf->address);
> break;
> case IOMAP_MAPPED:
> - error = copy_cow_page_dax(iter->iomap.bdev, iter->iomap.dax_dev,
> - sector, vmf->cow_page, vaddr);
> + error = copy_cow_page_dax(vmf, iter);
> break;
> default:
> WARN_ON_ONCE(1);
> --
> 2.30.2
>