ext2: huge page fault support

Use DAX to provide support for huge pages.
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ext2/file.c

@@ -32,6 +32,12 @@ static int ext2_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 	return dax_fault(vma, vmf, ext2_get_block, NULL);
 }
 
+static int ext2_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
+						pmd_t *pmd, unsigned int flags)
+{
+	return dax_pmd_fault(vma, addr, pmd, flags, ext2_get_block, NULL);
+}
+
 static int ext2_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	return dax_mkwrite(vma, vmf, ext2_get_block, NULL);
@@ -39,6 +45,7 @@ static int ext2_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 
 static const struct vm_operations_struct ext2_dax_vm_ops = {
 	.fault		= ext2_dax_fault,
+	.pmd_fault	= ext2_dax_pmd_fault,
 	.page_mkwrite	= ext2_dax_mkwrite,
 	.pfn_mkwrite	= dax_pfn_mkwrite,
 };
@@ -50,7 +57,7 @@ static int ext2_file_mmap(struct file *file, struct vm_area_struct *vma)
 
 	file_accessed(file);
 	vma->vm_ops = &ext2_dax_vm_ops;
-	vma->vm_flags |= VM_MIXEDMAP;
+	vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
 	return 0;
 }
 #else