io_uring: add BUILD_BUG_ON() to assert the layout of struct io_uring_sqe

With nesting of anonymous unions and structs it's hard to
review layout changes. It's better to ask the compiler
for these things.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 81a787b..217721c 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7038,6 +7038,39 @@ out_fput:
 
 static int __init io_uring_init(void)
 {
+#define __BUILD_BUG_VERIFY_ELEMENT(stype, eoffset, etype, ename) do { \
+       BUILD_BUG_ON(offsetof(stype, ename) != eoffset); \
+       BUILD_BUG_ON(sizeof(etype) != sizeof_field(stype, ename)); \
+} while (0)
+
+#define BUILD_BUG_SQE_ELEM(eoffset, etype, ename) \
+       __BUILD_BUG_VERIFY_ELEMENT(struct io_uring_sqe, eoffset, etype, ename)
+       BUILD_BUG_ON(sizeof(struct io_uring_sqe) != 64);
+       BUILD_BUG_SQE_ELEM(0,  __u8,   opcode);
+       BUILD_BUG_SQE_ELEM(1,  __u8,   flags);
+       BUILD_BUG_SQE_ELEM(2,  __u16,  ioprio);
+       BUILD_BUG_SQE_ELEM(4,  __s32,  fd);
+       BUILD_BUG_SQE_ELEM(8,  __u64,  off);
+       BUILD_BUG_SQE_ELEM(8,  __u64,  addr2);
+       BUILD_BUG_SQE_ELEM(16, __u64,  addr);
+       BUILD_BUG_SQE_ELEM(24, __u32,  len);
+       BUILD_BUG_SQE_ELEM(28,     __kernel_rwf_t, rw_flags);
+       BUILD_BUG_SQE_ELEM(28, /* compat */   int, rw_flags);
+       BUILD_BUG_SQE_ELEM(28, /* compat */ __u32, rw_flags);
+       BUILD_BUG_SQE_ELEM(28, __u32,  fsync_flags);
+       BUILD_BUG_SQE_ELEM(28, __u16,  poll_events);
+       BUILD_BUG_SQE_ELEM(28, __u32,  sync_range_flags);
+       BUILD_BUG_SQE_ELEM(28, __u32,  msg_flags);
+       BUILD_BUG_SQE_ELEM(28, __u32,  timeout_flags);
+       BUILD_BUG_SQE_ELEM(28, __u32,  accept_flags);
+       BUILD_BUG_SQE_ELEM(28, __u32,  cancel_flags);
+       BUILD_BUG_SQE_ELEM(28, __u32,  open_flags);
+       BUILD_BUG_SQE_ELEM(28, __u32,  statx_flags);
+       BUILD_BUG_SQE_ELEM(28, __u32,  fadvise_advice);
+       BUILD_BUG_SQE_ELEM(32, __u64,  user_data);
+       BUILD_BUG_SQE_ELEM(40, __u16,  buf_index);
+       BUILD_BUG_SQE_ELEM(42, __u16,  personality);
+
        BUILD_BUG_ON(ARRAY_SIZE(io_op_defs) != IORING_OP_LAST);
        req_cachep = KMEM_CACHE(io_kiocb, SLAB_HWCACHE_ALIGN | SLAB_PANIC);
        return 0;