Re: [PATCH 3/7] fsdax: Copy data before write

Christoph Hellwig
2021-02-08T15:14:25Z

> switch (iomap.type) {
> case IOMAP_MAPPED:
> +cow:
> if (iomap.flags & IOMAP_F_NEW) {
> count_vm_event(PGMAJFAULT);
> count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
> major = VM_FAULT_MAJOR;
> }
> error = dax_iomap_direct_access(&iomap, pos, PAGE_SIZE,
> - NULL, &pfn);
> + &kaddr, &pfn);

Any chance you could look into factoring out this code into a helper
to avoid the goto magic, which is a little too convoluted?

> switch (iomap.type) {
> case IOMAP_MAPPED:
> +cow:
> error = dax_iomap_direct_access(&iomap, pos, PMD_SIZE,
> - NULL, &pfn);
> + &kaddr, &pfn);
> if (error < 0)
> goto finish_iomap;
>
> entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn,
> DAX_PMD, write && !sync);
>
> + if (srcmap.type != IOMAP_HOLE) {

Same here.