device-dax: remove pfn from __dev_dax_{pte,pmd,pud}_fault()

After moving the page mapping to be set prior to pte insertion, the pfn
in dev_dax_huge_fault() no longer is necessary.  Remove it, as well as
the @pfn argument passed to the internal fault handler helpers.

[akpm@linux-foundation.org: fix CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD=n build]

Link: https://lkml.kernel.org/r/20211202204422.26777-11-joao.m.martins@oracle.com
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Suggested-by: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: jpemartins

drivers/dax/device.c

@@ -95,10 +95,11 @@ static void dax_set_mapping(struct vm_fault *vmf, pfn_t pfn,
 }
 
 static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax,
-				struct vm_fault *vmf, pfn_t *pfn)
+				struct vm_fault *vmf)
 {
 	struct device *dev = &dev_dax->dev;
 	phys_addr_t phys;
+	pfn_t pfn;
 	unsigned int fault_size = PAGE_SIZE;
 
 	if (check_vma(dev_dax, vmf->vma, __func__))
@@ -119,20 +120,21 @@ static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax,
 		return VM_FAULT_SIGBUS;
 	}
 
-	*pfn = phys_to_pfn_t(phys, PFN_DEV|PFN_MAP);
+	pfn = phys_to_pfn_t(phys, PFN_DEV|PFN_MAP);
 
-	dax_set_mapping(vmf, *pfn, fault_size);
+	dax_set_mapping(vmf, pfn, fault_size);
 
-	return vmf_insert_mixed(vmf->vma, vmf->address, *pfn);
+	return vmf_insert_mixed(vmf->vma, vmf->address, pfn);
 }
 
 static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax,
-				struct vm_fault *vmf, pfn_t *pfn)
+				struct vm_fault *vmf)
 {
 	unsigned long pmd_addr = vmf->address & PMD_MASK;
 	struct device *dev = &dev_dax->dev;
 	phys_addr_t phys;
 	pgoff_t pgoff;
+	pfn_t pfn;
 	unsigned int fault_size = PMD_SIZE;
 
 	if (check_vma(dev_dax, vmf->vma, __func__))
@@ -161,21 +163,22 @@ static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax,
 		return VM_FAULT_SIGBUS;
 	}
 
-	*pfn = phys_to_pfn_t(phys, PFN_DEV|PFN_MAP);
+	pfn = phys_to_pfn_t(phys, PFN_DEV|PFN_MAP);
 
-	dax_set_mapping(vmf, *pfn, fault_size);
+	dax_set_mapping(vmf, pfn, fault_size);
 
-	return vmf_insert_pfn_pmd(vmf, *pfn, vmf->flags & FAULT_FLAG_WRITE);
+	return vmf_insert_pfn_pmd(vmf, pfn, vmf->flags & FAULT_FLAG_WRITE);
 }
 
 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
-				struct vm_fault *vmf, pfn_t *pfn)
+				struct vm_fault *vmf)
 {
 	unsigned long pud_addr = vmf->address & PUD_MASK;
 	struct device *dev = &dev_dax->dev;
 	phys_addr_t phys;
 	pgoff_t pgoff;
+	pfn_t pfn;
 	unsigned int fault_size = PUD_SIZE;
 
 
@@ -205,15 +208,15 @@ static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
 		return VM_FAULT_SIGBUS;
 	}
 
-	*pfn = phys_to_pfn_t(phys, PFN_DEV|PFN_MAP);
+	pfn = phys_to_pfn_t(phys, PFN_DEV|PFN_MAP);
 
-	dax_set_mapping(vmf, *pfn, fault_size);
+	dax_set_mapping(vmf, pfn, fault_size);
 
-	return vmf_insert_pfn_pud(vmf, *pfn, vmf->flags & FAULT_FLAG_WRITE);
+	return vmf_insert_pfn_pud(vmf, pfn, vmf->flags & FAULT_FLAG_WRITE);
 }
 #else
 static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
-				struct vm_fault *vmf, pfn_t *pfn)
+				struct vm_fault *vmf)
 {
 	return VM_FAULT_FALLBACK;
 }
@@ -225,7 +228,6 @@ static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf,
 	struct file *filp = vmf->vma->vm_file;
 	vm_fault_t rc = VM_FAULT_SIGBUS;
 	int id;
-	pfn_t pfn;
 	struct dev_dax *dev_dax = filp->private_data;
 
 	dev_dbg(&dev_dax->dev, "%s: %s (%#lx - %#lx) size = %d\n", current->comm,
@@ -235,13 +237,13 @@ static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf,
 	id = dax_read_lock();
 	switch (pe_size) {
 	case PE_SIZE_PTE:
-		rc = __dev_dax_pte_fault(dev_dax, vmf, &pfn);
+		rc = __dev_dax_pte_fault(dev_dax, vmf);
 		break;
 	case PE_SIZE_PMD:
-		rc = __dev_dax_pmd_fault(dev_dax, vmf, &pfn);
+		rc = __dev_dax_pmd_fault(dev_dax, vmf);
 		break;
 	case PE_SIZE_PUD:
-		rc = __dev_dax_pud_fault(dev_dax, vmf, &pfn);
+		rc = __dev_dax_pud_fault(dev_dax, vmf);
 		break;
 	default:
 		rc = VM_FAULT_SIGBUS;