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[PATCH 1/6] qemu-img: rebase: stop when reaching EOF of old backing file
From: |
Andrey Drobyshev |
Subject: |
[PATCH 1/6] qemu-img: rebase: stop when reaching EOF of old backing file |
Date: |
Thu, 1 Jun 2023 22:28:31 +0300 |
In case when we're rebasing within one backing chain, and when target image
is larger than old backing file, bdrv_is_allocated_above() ends up setting
*pnum = 0. As a result, target offset isn't getting incremented, and we
get stuck in an infinite for loop. Let's detect this case and proceed
further down the loop body, as the offsets beyond the old backing size need
to be explicitly zeroed.
Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
---
qemu-img.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/qemu-img.c b/qemu-img.c
index 27f48051b0..78433f3746 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -3801,6 +3801,8 @@ static int img_rebase(int argc, char **argv)
}
if (prefix_chain_bs) {
+ uint64_t bytes = n;
+
/*
* If cluster wasn't changed since prefix_chain, we don't need
* to take action
@@ -3813,9 +3815,18 @@ static int img_rebase(int argc, char **argv)
strerror(-ret));
goto out;
}
- if (!ret) {
+ if (!ret && n) {
continue;
}
+ if (!n) {
+ /*
+ * If we've reached EOF of the old backing, it means that
+ * offsets beyond the old backing size were read as zeroes.
+ * Now we will need to explicitly zero the cluster in
+ * order to preserve that state after the rebase.
+ */
+ n = bytes;
+ }
}
/*
--
2.31.1
- [PATCH 6/6] iotests: add test 314 for "qemu-img rebase" with compression, (continued)
- [PATCH 6/6] iotests: add test 314 for "qemu-img rebase" with compression, Andrey Drobyshev, 2023/06/01
- [PATCH 2/6] qemu-iotests: 024: add rebasing test case for overlay_size > backing_size, Andrey Drobyshev, 2023/06/01
- [PATCH 3/6] qemu-img: rebase: use backing files' BlockBackend for buffer alignment, Andrey Drobyshev, 2023/06/01
- [PATCH 4/6] qemu-img: rebase: avoid unnecessary COW operations, Andrey Drobyshev, 2023/06/01
- [PATCH 5/6] qemu-img: add compression option to rebase subcommand, Andrey Drobyshev, 2023/06/01
- [PATCH 1/6] qemu-img: rebase: stop when reaching EOF of old backing file,
Andrey Drobyshev <=
- Re: [PATCH 0/6] qemu-img: rebase: add compression support, Denis V. Lunev, 2023/06/30