io_uring: io_kiocb_update_pos() should not touch file for non -1 offset

-1 tells use to use the current position, but we check if the file is
a stream regardless of that. Fix up io_kiocb_update_pos() to only
dip into file if we need to. This is both more efficient and also drops
12 bytes of text on aarch64 and 64 bytes on x86-64.

Fixes: b4aec4001595 ("io_uring: do not recalculate ppos unnecessarily")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index f060ad0..b4a5e2a 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3183,19 +3183,18 @@ static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret)
 static inline loff_t *io_kiocb_update_pos(struct io_kiocb *req)
 {
        struct kiocb *kiocb = &req->rw.kiocb;
-       bool is_stream = req->file->f_mode & FMODE_STREAM;
 
-       if (kiocb->ki_pos == -1) {
-               if (!is_stream) {
-                       req->flags |= REQ_F_CUR_POS;
-                       kiocb->ki_pos = req->file->f_pos;
-                       return &kiocb->ki_pos;
-               } else {
-                       kiocb->ki_pos = 0;
-                       return NULL;
-               }
+       if (kiocb->ki_pos != -1)
+               return &kiocb->ki_pos;
+
+       if (!(req->file->f_mode & FMODE_STREAM)) {
+               req->flags |= REQ_F_CUR_POS;
+               kiocb->ki_pos = req->file->f_pos;
+               return &kiocb->ki_pos;
        }
-       return is_stream ? NULL : &kiocb->ki_pos;
+
+       kiocb->ki_pos = 0;
+       return NULL;
 }
 
 static void kiocb_done(struct io_kiocb *req, ssize_t ret,