[PATCH 08/13] loop: Remove memory barriers

Now that all lo_state and lo_backing_file accesses from the control path
are serialized by lo_mutex, it is no longer necessary to use memory
barriers to order the lo_state and lo_backing_file accesses. Hence,
remove these memory barriers. While several lockless accesses of these
two member variables remain in the I/O path, these are serialized with
backing file changes by freezing the request queue. See also
loop_change_fd().

Signed-off-by: Bart Van Assche <[email protected]>
---
 drivers/block/loop.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 8b633ea6e72f..93b589bc6e3d 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -515,11 +515,6 @@ static struct file *loop_get_backing_file(struct loop_device *lo)
 {
 	if (lo->lo_state != Lo_bound)
 		return NULL;
-	/*
-	 * Order wrt setting lo->lo_backing_file in
-	 * loop_configure().
-	 */
-	rmb();
 	return get_file(lo->lo_backing_file);
 }
 
@@ -1149,9 +1144,6 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode,
 	size = lo_calculate_size(lo, file);
 	loop_set_size(lo, size);
 
-	/* Order wrt reading lo_state in loop_validate_file(). */
-	wmb();
-
 	WRITE_ONCE(lo->lo_state, Lo_bound);
 	if (part_shift)
 		lo->lo_flags |= LO_FLAGS_PARTSCAN;