From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Stefan Reiter Date: Tue, 2 Mar 2021 16:11:54 +0100 Subject: [PATCH] block/io: accept NULL qiov in bdrv_pad_request Some operations, e.g. block-stream, perform reads while discarding the results (only copy-on-read matters). In this case they will pass NULL as the target QEMUIOVector, which will however trip bdrv_pad_request, since it wants to extend its passed vector. Simply check for NULL and do nothing, there's no reason to pad the target if it will be discarded anyway. --- block/io.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/block/io.c b/block/io.c index ec5e152bb7..08dee005ec 100644 --- a/block/io.c +++ b/block/io.c @@ -1613,13 +1613,16 @@ static bool bdrv_pad_request(BlockDriverState *bs, return false; } - qemu_iovec_init_extended(&pad->local_qiov, pad->buf, pad->head, - *qiov, *qiov_offset, *bytes, - pad->buf + pad->buf_len - pad->tail, pad->tail); + if (*qiov) { + qemu_iovec_init_extended(&pad->local_qiov, pad->buf, pad->head, + *qiov, *qiov_offset, *bytes, + pad->buf + pad->buf_len - pad->tail, pad->tail); + *qiov = &pad->local_qiov; + *qiov_offset = 0; + } + *bytes += pad->head + pad->tail; *offset -= pad->head; - *qiov = &pad->local_qiov; - *qiov_offset = 0; return true; }