Am 04.09.19 um 16:09 schrieb Kevin Wolf:
Am 03.09.2019 um 15:35 hat Peter Lieven geschrieben:
qemu is currently not able to detect truncated vhdx image files.
Add a basic check if all allocated blocks are reachable at open and
report all errors during bdrv_co_check.
Signed-off-by: Peter Lieven <p...@kamp.de>
---
V3: - check for bdrv_getlength failure [Kevin]
- use uint32_t for i [Kevin]
- check for BAT entry overflow [Kevin]
- break on !errcnt in second check
V2: - add error reporting [Kevin]
- use bdrv_getlength instead of bdrv_get_allocated_file_size [Kevin]
- factor out BAT entry check and add error reporting for region
overlaps
- already check on vhdx_open
Something still seems to be wrong with this patch:
213 fail [15:50:13] [15:50:14] (last: 2s) output
mismatch (see 213.out.bad)
--- /home/kwolf/source/qemu/tests/qemu-iotests/213.out 2019-06-28
14:19:50.065797707 +0200
+++ /home/kwolf/source/qemu/tests/qemu-iotests/213.out.bad 2019-09-04
15:50:14.582053976 +0200
@@ -46,10 +46,8 @@
{"execute": "job-dismiss", "arguments": {"id": "job0"}}
{"return": {}}
-image: TEST_IMG
-file format: IMGFMT
-virtual size: 32 MiB (33554432 bytes)
-cluster_size: 268435456
+qemu-img: VHDX BAT entry 0 offset points after end of file. Image has
probably been truncated.
+qemu-img: Could not open 'TEST_IMG': Could not open 'TEST_IMG': Invalid
argument
=== Invalid BlockdevRef ===
I can reproduce this manually with the following qemu-img invocations.
It seems all three options must be given to reproduce the error:
$ ./qemu-img create -f vhdx -o
block_size=268435456,subformat=fixed,block_state_zero=off /tmp/test.vhdx 32M
Formatting '/tmp/test.vhdx', fmt=vhdx size=33554432 log_size=1048576
block_size=268435456 subformat=fixed block_state_zero=off
$ ./qemu-img info /tmp/test.vhdx
qemu-img: VHDX BAT entry 0 offset points after end of file. Image has
probably been truncated.
qemu-img: Could not open '/tmp/test.vhdx': Could not open
'/tmp/test.vhdx': Invalid argument
If I add the offsets to the error message (would probably nice to have),
I get:
qemu-img: VHDX BAT entry 0 offset 8388608 points after end of file
(41943040). Image has probably been truncated.
So it seems that the file is large enough to hold 32M + metadata, but we
don't increase the file size to hold a full block (256M). Is this a
problem in the way we create images or are partial blocks at the end
expected?
Kevin
A short look into the VHDX spec [1] seems to suggest that a VHDX File can only
grow in Block increments.
See page 8 in the definition of blocks: "Allocation of new space for a virtual
hard disk that supports dynamic growth
of the virtual hard disk file is done in fixes size units defined as blocks."
Peter
[1] https://www.microsoft.com/en-us/download/confirmation.aspx?id=34750
--
Mit freundlichen Grüßen
Peter Lieven
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