gfs2: Clean up use of fault_in_iov_iter_{read,write}able

No need to store the return value of the fault_in functions in separate
variables.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

fs/gfs2/file.c

@@ -846,12 +846,10 @@ static ssize_t gfs2_file_direct_read(struct kiocb *iocb, struct iov_iter *to,
 		read = ret;
 
 	if (should_fault_in_pages(ret, to, &prev_count, &window_size)) {
-		size_t leftover;
-
 		gfs2_holder_allow_demote(gh);
-		leftover = fault_in_iov_iter_writeable(to, window_size);
+		window_size -= fault_in_iov_iter_writeable(to, window_size);
 		gfs2_holder_disallow_demote(gh);
-		if (leftover != window_size) {
+		if (window_size) {
 			if (gfs2_holder_queued(gh))
 				goto retry_under_glock;
 			goto retry;
@@ -915,12 +913,10 @@ static ssize_t gfs2_file_direct_write(struct kiocb *iocb, struct iov_iter *from,
 		written = ret;
 
 	if (should_fault_in_pages(ret, from, &prev_count, &window_size)) {
-		size_t leftover;
-
 		gfs2_holder_allow_demote(gh);
-		leftover = fault_in_iov_iter_readable(from, window_size);
+		window_size -= fault_in_iov_iter_readable(from, window_size);
 		gfs2_holder_disallow_demote(gh);
-		if (leftover != window_size) {
+		if (window_size) {
 			if (gfs2_holder_queued(gh))
 				goto retry_under_glock;
 			goto retry;
@@ -983,12 +979,10 @@ static ssize_t gfs2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 		read += ret;
 
 	if (should_fault_in_pages(ret, to, &prev_count, &window_size)) {
-		size_t leftover;
-
 		gfs2_holder_allow_demote(&gh);
-		leftover = fault_in_iov_iter_writeable(to, window_size);
+		window_size -= fault_in_iov_iter_writeable(to, window_size);
 		gfs2_holder_disallow_demote(&gh);
-		if (leftover != window_size) {
+		if (window_size) {
 			if (gfs2_holder_queued(&gh))
 				goto retry_under_glock;
 			goto retry;
@@ -1058,13 +1052,11 @@ static ssize_t gfs2_file_buffered_write(struct kiocb *iocb,
 
 	from->count = orig_count - written;
 	if (should_fault_in_pages(ret, from, &prev_count, &window_size)) {
-		size_t leftover;
-
 		gfs2_holder_allow_demote(gh);
-		leftover = fault_in_iov_iter_readable(from, window_size);
+		window_size -= fault_in_iov_iter_readable(from, window_size);
 		gfs2_holder_disallow_demote(gh);
-		if (leftover != window_size) {
-			from->count = min(from->count, window_size - leftover);
+		if (window_size) {
+			from->count = min(from->count, window_size);
 			if (gfs2_holder_queued(gh))
 				goto retry_under_glock;
 			goto retry;