From: Jens Axboe <axboe@xxxxxxxxx> commit 5e559561a8d7e6d4adfce6aa8fbf3daa3dec1577 upstream. A test case was reported where two linked reads with registered buffers failed the second link always. This is because we set the expected value of a request in req->result, and if we don't get this result, then we fail the dependent links. For some reason the registered buffer import returned -ERROR/0, while the normal import returns -ERROR/length. This broke linked commands with registered buffers. Fix this by making io_import_fixed() correctly return the mapped length. Cc: stable@xxxxxxxxxxxxxxx # v5.3 Reported-by: 李通洲 <carter.li@xxxxxxxxxx> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/io_uring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1179,7 +1179,7 @@ static int io_import_fixed(struct io_rin } } - return 0; + return len; } static ssize_t io_import_iovec(struct io_ring_ctx *ctx, int rw,
