dax: Create local variable for vmf->flags & FAULT_FLAG_WRITE test

There are already two users and more are coming.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

fs/dax.c

@@ -1116,6 +1116,7 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf,
 	struct iomap iomap = { 0 };
 	unsigned flags = IOMAP_FAULT;
 	int error, major = 0;
+	bool write = vmf->flags & FAULT_FLAG_WRITE;
 	int vmf_ret = 0;
 	void *entry;
 
@@ -1130,7 +1131,7 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf,
 		goto out;
 	}
 
-	if ((vmf->flags & FAULT_FLAG_WRITE) && !vmf->cow_page)
+	if (write && !vmf->cow_page)
 		flags |= IOMAP_WRITE;
 
 	entry = grab_mapping_entry(mapping, vmf->pgoff, 0);
@@ -1207,7 +1208,7 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf,
 		break;
 	case IOMAP_UNWRITTEN:
 	case IOMAP_HOLE:
-		if (!(vmf->flags & FAULT_FLAG_WRITE)) {
+		if (!write) {
 			vmf_ret = dax_load_hole(mapping, entry, vmf);
 			goto finish_iomap;
 		}