io_uring: remove __io_file_supports_nowait

Now that this only checks O_NONBLOCK and FMODE_NOWAIT, the helper is
complete overkilļ, and the comments are confusing bordering to wrong.
Just inline the check into the caller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230620113235.920399-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/io_uring.c

@@ -1766,19 +1766,6 @@ static void io_iopoll_req_issued(struct io_kiocb *req, unsigned int issue_flags)
 	}
 }
 
-/*
- * If we tracked the file through the SCM inflight mechanism, we could support
- * any file. For now, just ensure that anything potentially problematic is done
- * inline.
- */
-static bool __io_file_supports_nowait(struct file *file, umode_t mode)
-{
-	/* any ->read/write should understand O_NONBLOCK */
-	if (file->f_flags & O_NONBLOCK)
-		return true;
-	return file->f_mode & FMODE_NOWAIT;
-}
-
 /*
  * If we tracked the file through the SCM inflight mechanism, we could support
  * any file. For now, just ensure that anything potentially problematic is done
@@ -1791,7 +1778,7 @@ unsigned int io_file_get_flags(struct file *file)
 
 	if (S_ISREG(mode))
 		res |= FFS_ISREG;
-	if (__io_file_supports_nowait(file, mode))
+	if ((file->f_flags & O_NONBLOCK) || (file->f_mode & FMODE_NOWAIT))
 		res |= FFS_NOWAIT;
 	return res;
 }