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e4d7019e1a
After commit f01643fb8b when an image is
extended and BDRV_REQ_ZERO_WRITE is set then the new clusters are
zeroized.
The code however does not detect correctly situations when the old and
the new end of the image are within the same cluster. The problem can
be reproduced with these steps:
qemu-img create -f qcow2 backing.qcow2 1M
qemu-img create -f qcow2 -F qcow2 -b backing.qcow2 top.qcow2
qemu-img resize --shrink top.qcow2 520k
qemu-img resize top.qcow2 567k
In the last step offset - zero_start causes an integer wraparound.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-Id: <20200504155217.10325-1-berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
25 lines
1013 B
Plaintext
25 lines
1013 B
Plaintext
QA output created by 292
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### Create the backing image
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Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=1048576
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### Fill the backing image with data (0x11)
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wrote 1048576/1048576 bytes at offset 0
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1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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### Create the top image
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=1048576 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
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### Fill the top image with data (0x22)
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wrote 1048576/1048576 bytes at offset 0
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1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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### Shrink the image to 520k
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Image resized.
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### Grow the image to 567k
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Image resized.
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### Check that the tail of the image reads as zeroes
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read 532480/532480 bytes at offset 0
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520 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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read 48128/48128 bytes at offset 532480
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47 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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### Show output of qemu-img map
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Offset Length Mapped to File
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0 0x8dc00 0x50000 TEST_DIR/t.qcow2
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*** done
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