048c5fd1bf
As mentioned in commit 0c1bd46, we ignored requests to
discard the trailing cluster of an unaligned image. While
discard is an advisory operation from the guest standpoint,
(and we are therefore free to ignore any request), our
qcow2 implementation exploits the fact that a discarded
cluster reads back as 0. As long as we discard on cluster
boundaries, we are fine; but that means we could observe
non-zero data leaked at the tail of an unaligned image.
Enhance iotest 66 to cover this case, and fix the implementation
to honor a discard request on the final partial cluster.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-id: 20170407013709.18440-1-eblake@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
18 lines
646 B
Plaintext
18 lines
646 B
Plaintext
QA output created by 066
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=== Testing cluster discards ===
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67109376
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wrote 262144/262144 bytes at offset 0
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256 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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wrote 262144/262144 bytes at offset 0
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256 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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wrote 512/512 bytes at offset 67108864
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512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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discard 67109376/67109376 bytes at offset 0
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64 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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read 67109376/67109376 bytes at offset 0
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64 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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No errors were found on the image.
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*** done
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