65 lines
2.3 KiB
Diff
65 lines
2.3 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Stefan Reiter <s.reiter@proxmox.com>
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Date: Tue, 2 Mar 2021 16:11:54 +0100
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Subject: [PATCH] block/io: accept NULL qiov in bdrv_pad_request
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Some operations, e.g. block-stream, perform reads while discarding the
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results (only copy-on-read matters). In this case they will pass NULL as
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the target QEMUIOVector, which will however trip bdrv_pad_request, since
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it wants to extend its passed vector.
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If there is no qiov, no operation can be done with it, but the bytes
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and offset still need to be updated, so the subsequent aligned read
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will actually be aligned and not run into an assertion failure.
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Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
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[FE: do update bytes and offset in any case]
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Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
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---
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block/io.c | 29 ++++++++++++++++-------------
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1 file changed, 16 insertions(+), 13 deletions(-)
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diff --git a/block/io.c b/block/io.c
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index d202987770..d42c811bd7 100644
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--- a/block/io.c
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+++ b/block/io.c
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@@ -1756,22 +1756,25 @@ static int bdrv_pad_request(BlockDriverState *bs,
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return 0;
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}
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- sliced_iov = qemu_iovec_slice(*qiov, *qiov_offset, *bytes,
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- &sliced_head, &sliced_tail,
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- &sliced_niov);
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-
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- /* Guaranteed by bdrv_check_request32() */
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- assert(*bytes <= SIZE_MAX);
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- ret = bdrv_create_padded_qiov(bs, pad, sliced_iov, sliced_niov,
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- sliced_head, *bytes);
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- if (ret < 0) {
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- bdrv_padding_finalize(pad);
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- return ret;
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+ if (qiov && *qiov) {
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+ sliced_iov = qemu_iovec_slice(*qiov, *qiov_offset, *bytes,
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+ &sliced_head, &sliced_tail,
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+ &sliced_niov);
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+
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+ /* Guaranteed by bdrv_check_request32() */
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+ assert(*bytes <= SIZE_MAX);
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+ ret = bdrv_create_padded_qiov(bs, pad, sliced_iov, sliced_niov,
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+ sliced_head, *bytes);
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+ if (ret < 0) {
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+ bdrv_padding_finalize(pad);
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+ return ret;
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+ }
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+ *qiov = &pad->local_qiov;
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+ *qiov_offset = 0;
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}
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+
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*bytes += pad->head + pad->tail;
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*offset -= pad->head;
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- *qiov = &pad->local_qiov;
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- *qiov_offset = 0;
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if (padded) {
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*padded = true;
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}
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