io_uring/rw: cast rw->flags assignment to rwf_t

kernel test robot reports that a recent change of the sqe->rw_flags
field throws a sparse warning on 32-bit archs:

>> io_uring/rw.c:291:19: sparse: sparse: incorrect type in assignment (different base types) @@     expected restricted __kernel_rwf_t [usertype] flags @@     got unsigned int @@
   io_uring/rw.c:291:19: sparse:     expected restricted __kernel_rwf_t [usertype] flags
   io_uring/rw.c:291:19: sparse:     got unsigned int

Force cast it to rwf_t to silence that new sparse warning.

Fixes: cf73d99 ("io_uring: don't use int for ABI")
Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Signed-off-by: Jens Axboe <[email protected]>

Author: axboe

io_uring/rw.c

@@ -288,7 +288,7 @@ static int __io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 
 	rw->addr = READ_ONCE(sqe->addr);
 	rw->len = READ_ONCE(sqe->len);
-	rw->flags = READ_ONCE(sqe->rw_flags);
+	rw->flags = (__force rwf_t) READ_ONCE(sqe->rw_flags);
 
 	attr_type_mask = READ_ONCE(sqe->attr_type_mask);
 	if (attr_type_mask) {