io_uring: remove bogus RLIMIT_NOFILE check in file registration

to #28170604

commit c336e992cb1cb1db9ee608dfb30342ae781057ab upstream

We already checked this limit when the file was opened, and we keep it
open in the file table. Hence when we added unit_inflight to the count
we want to register, we're doubly accounting these files. This results
in -EMFILE for file registration, if we're at half the limit.

Cc: stable@vger.kernel.org # v5.1+
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Signed-off-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>

fs/io_uring.c

@@ -6215,13 +6215,6 @@ static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
 	struct sk_buff *skb;
 	int i, nr_files;
 
-	if (!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {
-		unsigned long inflight = ctx->user->unix_inflight + nr;
-
-		if (inflight > task_rlimit(current, RLIMIT_NOFILE))
-			return -EMFILE;
-	}
-
 	fpl = kzalloc(sizeof(*fpl), GFP_KERNEL);
 	if (!fpl)
 		return -ENOMEM;