fs: ext4: add new return type vm_fault_t

Use new return type vm_fault_t for fault handler. For now,
this is just documenting that the function returns a
VM_FAULT value rather than an errno. Once all instances are
converted, vm_fault_t will become a distinct type.

commit 1c8f422 ("mm: change return type to vm_fault_t")

Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>

fs/ext4/file.c

@@ -277,10 +277,11 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 }
 
 #ifdef CONFIG_FS_DAX
-static int ext4_dax_huge_fault(struct vm_fault *vmf,
+static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf,
 		enum page_entry_size pe_size)
 {
-	int result, error = 0;
+	int error = 0;
+	vm_fault_t result;
 	int retries = 0;
 	handle_t *handle = NULL;
 	struct inode *inode = file_inode(vmf->vma->vm_file);
@@ -335,7 +336,7 @@ static int ext4_dax_huge_fault(struct vm_fault *vmf,
 	return result;
 }
 
-static int ext4_dax_fault(struct vm_fault *vmf)
+static vm_fault_t ext4_dax_fault(struct vm_fault *vmf)
 {
 	return ext4_dax_huge_fault(vmf, PE_SIZE_PTE);
 }