[PATCH RFC 07/14] fs/dax: use vmf_insert_folio_pmd() to insert the huge zero folio

[David Hildenbrand]

Let's convert to vmf_insert_folio_pmd().

In the unlikely case there is already something mapped, we'll now still
call trace_dax_pmd_load_hole() and return VM_FAULT_NOPAGE.

That should probably be fine, no need to add special cases for that.

Signed-off-by: David Hildenbrand <da...@redhat.com>
---
 fs/dax.c | 47 ++++++++++-------------------------------------
 1 file changed, 10 insertions(+), 37 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 4229513806bea..ae90706674a3f 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1375,51 +1375,24 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state 
*xas, struct vm_fault *vmf,
                const struct iomap_iter *iter, void **entry)
 {
        struct address_space *mapping = vmf->vma->vm_file->f_mapping;
-       unsigned long pmd_addr = vmf->address & PMD_MASK;
-       struct vm_area_struct *vma = vmf->vma;
        struct inode *inode = mapping->host;
-       pgtable_t pgtable = NULL;
        struct folio *zero_folio;
-       spinlock_t *ptl;
-       pmd_t pmd_entry;
-       unsigned long pfn;
+       vm_fault_t ret;
 
        zero_folio = mm_get_huge_zero_folio(vmf->vma->vm_mm);
 
-       if (unlikely(!zero_folio))
-               goto fallback;
-
-       pfn = page_to_pfn(&zero_folio->page);
-       *entry = dax_insert_entry(xas, vmf, iter, *entry, pfn,
-                                 DAX_PMD | DAX_ZERO_PAGE);
-
-       if (arch_needs_pgtable_deposit()) {
-               pgtable = pte_alloc_one(vma->vm_mm);
-               if (!pgtable)
-                       return VM_FAULT_OOM;
-       }
-
-       ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
-       if (!pmd_none(*(vmf->pmd))) {
-               spin_unlock(ptl);
-               goto fallback;
+       if (unlikely(!zero_folio)) {
+               trace_dax_pmd_load_hole_fallback(inode, vmf, zero_folio, 
*entry);
+               return VM_FAULT_FALLBACK;
        }
 
-       if (pgtable) {
-               pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
-               mm_inc_nr_ptes(vma->vm_mm);
-       }
-       pmd_entry = folio_mk_pmd(zero_folio, vmf->vma->vm_page_prot);
-       set_pmd_at(vmf->vma->vm_mm, pmd_addr, vmf->pmd, pmd_entry);
-       spin_unlock(ptl);
-       trace_dax_pmd_load_hole(inode, vmf, zero_folio, *entry);
-       return VM_FAULT_NOPAGE;
+       *entry = dax_insert_entry(xas, vmf, iter, *entry, folio_pfn(zero_folio),
+                                 DAX_PMD | DAX_ZERO_PAGE);
 
-fallback:
-       if (pgtable)
-               pte_free(vma->vm_mm, pgtable);
-       trace_dax_pmd_load_hole_fallback(inode, vmf, zero_folio, *entry);
-       return VM_FAULT_FALLBACK;
+       ret = vmf_insert_folio_pmd(vmf, zero_folio, false);
+       if (ret == VM_FAULT_NOPAGE)
+               trace_dax_pmd_load_hole(inode, vmf, zero_folio, *entry);
+       return ret;
 }
 #else
 static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
-- 
2.49.0