io_uring: improve hardlink code generation

req_set_fail_links() condition checking is bulky. Even though it's
always in a slow path, it's inlined and generates lots of extra code,
simplify it be moving HARDLINK checking into helpers killing linked
requests.

          text    data     bss     dec     hex filename
before:  79318   12330       8   91656   16608 ./fs/io_uring.o
after:   79126   12330       8   91464   16548 ./fs/io_uring.o
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/96a9387db658a9d5a44ecbfd57c2a62cb888c9b6.1618101759.git.asml.silence@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -1101,7 +1101,7 @@ static bool io_match_task(struct io_kiocb *head,
 
 static inline void req_set_fail_links(struct io_kiocb *req)
 {
-	if ((req->flags & (REQ_F_LINK | REQ_F_HARDLINK)) == REQ_F_LINK)
+	if (req->flags & REQ_F_LINK)
 		req->flags |= REQ_F_FAIL_LINK;
 }
 
@@ -1810,7 +1810,8 @@ static bool io_disarm_next(struct io_kiocb *req)
 
 	if (likely(req->flags & REQ_F_LINK_TIMEOUT))
 		posted = io_kill_linked_timeout(req);
-	if (unlikely(req->flags & REQ_F_FAIL_LINK)) {
+	if (unlikely((req->flags & REQ_F_FAIL_LINK) &&
+		     !(req->flags & REQ_F_HARDLINK))) {
 		posted |= (req->link != NULL);
 		io_fail_links(req);
 	}