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qemu/tests/qemu-iotests/154
Eric Blake c61e684e44 block: Exploit BDRV_BLOCK_EOF for larger zero blocks 
When we have a BDS with unallocated clusters, but asking the status
of its underlying bs->file or backing layer encounters an end-of-file
condition, we know that the rest of the unallocated area will read as
zeroes.  However, pre-patch, this required two separate calls to
bdrv_get_block_status(), as the first call stops at the point where
the underlying file ends.  Thanks to BDRV_BLOCK_EOF, we can now widen
the results of the primary status if the secondary status already
includes BDRV_BLOCK_ZERO.

In turn, this fixes a TODO mentioned in iotest 154, where we can now
see that all sectors in a partial cluster at the end of a file read
as zero when coupling the shorter backing file's status along with our
knowledge that the remaining sectors came from an unallocated cluster.

Also, note that the loop in bdrv_co_get_block_status_above() had an
inefficent exit: in cases where the active layer sets BDRV_BLOCK_ZERO
but does NOT set BDRV_BLOCK_ALLOCATED (namely, where we know we read
zeroes merely because our unallocated clusters lie beyond the backing
file's shorter length), we still ended up probing the backing layer
even though we already had a good answer.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20170505021500.19315-3-eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
2017-06-30 21:48:06 +08:00

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#!/bin/bash
#
# qcow2 specific bdrv_pwrite_zeroes tests with backing files (complements 034)
#
# Copyright (C) 2016-2017 Red Hat, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
# creator
owner=kwolf@redhat.com
seq=`basename $0`
echo "QA output created by $seq"
here=`pwd`
status=1 # failure is the default!
_cleanup()
{
_cleanup_test_img
}
trap "_cleanup; exit \$status" 0 1 2 3 15
# get standard environment, filters and checks
. ./common.rc
. ./common.filter
_supported_fmt qcow2
_supported_proto file
_supported_os Linux
CLUSTER_SIZE=4k
size=$((128 * 1024 * 1024))
# This test requires zero clusters, added in v3 images
_unsupported_imgopts compat=0.10
echo
echo == backing file contains zeros ==
CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
_make_test_img -b "$TEST_IMG.base"
# Make sure that the whole cluster is allocated even for partial write_zeroes
# when the backing file contains zeros
# X = non-zero data sector in backing file
# - = sector unallocated in whole backing chain
# 0 = sector touched by write_zeroes request
# 1. Tail unaligned: 00 00 -- --
# 2. Head unaligned: -- -- 00 00
# 3. Both unaligned: -- 00 00 --
# 4. Both, 2 clusters: -- -- -- 00 | 00 -- -- --
$QEMU_IO -c "write -z 0 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "write -z 10k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "write -z 17k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "write -z 27k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
echo
echo == backing file contains non-zero data before write_zeroes ==
CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
_make_test_img -b "$TEST_IMG.base"
# Single cluster; non-zero data at the cluster start
# ... | XX -- 00 -- | ...
$QEMU_IO -c "write -P 0x11 32k 1k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 34k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0x11 32k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 33k 3k" "$TEST_IMG" | _filter_qemu_io
# Single cluster; non-zero data exists, but not at the cluster start
# ... | -- XX 00 -- | ...
$QEMU_IO -c "write -P 0x11 65k 1k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 66k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0x11 65k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 64k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 66k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
echo
echo == backing file contains non-zero data after write_zeroes ==
CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
_make_test_img -b "$TEST_IMG.base"
# Single cluster; non-zero data directly after request
# ... | -- 00 XX -- | ...
$QEMU_IO -c "write -P 0x11 34k 1k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 33k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 32k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0x11 34k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 35k 1k" "$TEST_IMG" | _filter_qemu_io
# Single cluster; non-zero data exists, but not directly after request
# ... | -- 00 -- XX | ...
$QEMU_IO -c "write -P 0x11 43k 1k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 41k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0x11 43k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 40k 3k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
echo
echo == write_zeroes covers non-zero data ==
CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
_make_test_img -b "$TEST_IMG.base"
# non-zero data at front of request
# Backing file: -- XX -- --
# Active layer: -- 00 00 --
$QEMU_IO -c "write -P 0x11 5k 1k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 5k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 4k 4k" "$TEST_IMG" | _filter_qemu_io
# non-zero data at end of request
# Backing file: -- -- XX --
# Active layer: -- 00 00 --
$QEMU_IO -c "write -P 0x11 14k 1k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 13k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 12k 4k" "$TEST_IMG" | _filter_qemu_io
# non-zero data matches size of request
# Backing file: -- XX XX --
# Active layer: -- 00 00 --
$QEMU_IO -c "write -P 0x11 21k 2k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 21k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 20k 4k" "$TEST_IMG" | _filter_qemu_io
# non-zero data smaller than request
# Backing file: -- -X X- --
# Active layer: -- 00 00 --
$QEMU_IO -c "write -P 0x11 30208 1k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 29k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 28k 4k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
echo
echo == spanning two clusters, non-zero before request ==
CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
_make_test_img -b "$TEST_IMG.base"
# Two clusters; non-zero data before request:
# 1. At cluster start: 32k: XX -- -- 00 | 00 -- -- --
# 2. Between unallocated space: 48k: -- XX -- 00 | 00 -- -- --
# 3. Directly before request: 64k: -- -- XX 00 | 00 -- -- --
$QEMU_IO -c "write -P 0x11 32k 1k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 35k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0x11 32k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 33k 7k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "write -P 0x11 49k 1k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 51k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 48k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0x11 49k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 50k 6k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "write -P 0x11 66k 1k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 67k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 64k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0x11 66k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 67k 5k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
echo
echo == spanning two clusters, non-zero after request ==
CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
_make_test_img -b "$TEST_IMG.base"
# Two clusters; non-zero data after request:
# 1. Directly after request: 32k: -- -- -- 00 | 00 XX -- --
# 2. Between unallocated space: 48k: -- -- -- 00 | 00 -- XX --
# 3. At cluster end: 64k: -- -- -- 00 | 00 -- -- XX
$QEMU_IO -c "write -P 0x11 37k 1k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 35k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 32k 5k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0x11 37k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 38k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "write -P 0x11 54k 1k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 51k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 48k 6k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0x11 54k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 55k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "write -P 0x11 71k 1k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 67k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 64k 7k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0x11 71k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
echo
echo == spanning two clusters, partially overwriting backing file ==
CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
_make_test_img -b "$TEST_IMG.base"
# Backing file: -- -- XX XX | XX XX -- --
# Active layer: -- -- XX 00 | 00 XX -- --
$QEMU_IO -c "write -P 0x11 2k 4k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 3k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 0k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0x11 2k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 3k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0x11 5k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 6k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
echo
echo == spanning multiple clusters, non-zero in first cluster ==
CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
_make_test_img -b "$TEST_IMG.base"
# Backing file: 64k: XX XX -- -- | -- -- -- -- | -- -- -- --
# Active layer: 64k: XX XX 00 00 | 00 00 00 00 | 00 -- -- --
$QEMU_IO -c "write -P 0x11 64k 2k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 66k 7k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0x11 64k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 66k 10k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
echo
echo == spanning multiple clusters, non-zero in intermediate cluster ==
CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
_make_test_img -b "$TEST_IMG.base"
# Backing file: 64k: -- -- -- -- | -- XX XX -- | -- -- -- --
# Active layer: 64k: -- -- 00 00 | 00 00 00 00 | 00 -- -- --
$QEMU_IO -c "write -P 0x11 69k 2k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 66k 7k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 64k 12k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
echo
echo == spanning multiple clusters, non-zero in final cluster ==
CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
_make_test_img -b "$TEST_IMG.base"
# Backing file: 64k: -- -- -- -- | -- -- -- -- | -- -- XX XX
# Active layer: 64k: -- -- 00 00 | 00 00 00 00 | 00 -- XX XX
$QEMU_IO -c "write -P 0x11 74k 2k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 66k 7k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 64k 10k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0x11 74k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
echo
echo == spanning multiple clusters, partially overwriting backing file ==
CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
_make_test_img -b "$TEST_IMG.base"
# Backing file: 64k: -- XX XX XX | XX XX XX XX | XX XX XX --
# Active layer: 64k: -- XX 00 00 | 00 00 00 00 | 00 XX XX --
$QEMU_IO -c "write -P 0x11 65k 10k" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z 66k 7k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 64k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0x11 65k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 66k 7k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0x11 73k 2k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 75k 1k" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
echo
echo == unaligned image tail cluster, no allocation needed ==
# With no backing file, write to all or part of unallocated partial cluster
# will mark the cluster as zero, but does not allocate.
# Re-create the image each time to get back to unallocated clusters.
# Write at the front: sector-wise, the request is: 128m... | 00 -- -- --
_make_test_img $((size + 2048))
$QEMU_IO -c "write -z $size 512" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
# Write at the back: sector-wise, the request is: 128m... | -- -- -- 00
_make_test_img $((size + 2048))
$QEMU_IO -c "write -z $((size + 1536)) 512" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
# Write at middle: sector-wise, the request is: 128m... | -- 00 00 --
_make_test_img $((size + 2048))
$QEMU_IO -c "write -z $((size + 512)) 1024" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
# Write entire cluster: sector-wise, the request is: 128m... | 00 00 00 00
_make_test_img $((size + 2048))
$QEMU_IO -c "write -z $size 2048" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
# Repeat with backing file holding unallocated cluster.
CLUSTER_SIZE=2048 TEST_IMG="$TEST_IMG.base" _make_test_img $((size + 1024))
# Write at the front: sector-wise, the request is:
# backing: 128m... | -- --
# active: 128m... | 00 -- -- --
_make_test_img -b "$TEST_IMG.base" $((size + 2048))
$QEMU_IO -c "write -z $size 512" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
# Write at the back: sector-wise, the request is:
# backing: 128m... | -- --
# active: 128m... | -- -- -- 00
_make_test_img -b "$TEST_IMG.base" $((size + 2048))
$QEMU_IO -c "write -z $((size + 1536)) 512" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
# Write at middle: sector-wise, the request is:
# backing: 128m... | -- --
# active: 128m... | -- 00 00 --
_make_test_img -b "$TEST_IMG.base" $((size + 2048))
$QEMU_IO -c "write -z $((size + 512)) 1024" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
# Write entire cluster: sector-wise, the request is:
# backing: 128m... | -- --
# active: 128m... | 00 00 00 00
_make_test_img -b "$TEST_IMG.base" $((size + 2048))
$QEMU_IO -c "write -z $size 2048" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
# Repeat with backing file holding zero'd cluster
$QEMU_IO -c "write -z $size 512" "$TEST_IMG.base" | _filter_qemu_io
# Write at the front: sector-wise, the request is:
# backing: 128m... | 00 00
# active: 128m... | 00 -- -- --
_make_test_img -b "$TEST_IMG.base" $((size + 2048))
$QEMU_IO -c "write -z $size 512" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
# Write at the back: sector-wise, the request is:
# backing: 128m... | 00 00
# active: 128m... | -- -- -- 00
_make_test_img -b "$TEST_IMG.base" $((size + 2048))
$QEMU_IO -c "write -z $((size + 1536)) 512" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
# Write at middle: sector-wise, the request is:
# backing: 128m... | 00 00
# active: 128m... | -- 00 00 --
_make_test_img -b "$TEST_IMG.base" $((size + 2048))
$QEMU_IO -c "write -z $((size + 512)) 1024" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
# Write entire cluster: sector-wise, the request is:
# backing: 128m... | 00 00
# active: 128m... | 00 00 00 00
_make_test_img -b "$TEST_IMG.base" $((size + 2048))
$QEMU_IO -c "write -z $size 2048" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
# A preallocated cluster maintains its allocation, whether it stays as
# data due to a partial write:
# Convert 128m... | XX XX => ... | XX 00
_make_test_img $((size + 1024))
$QEMU_IO -c "write -P 1 $((size)) 1024" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "write -z $((size + 512)) 512" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 1 $((size)) 512" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 $((size + 512)) 512" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "alloc $size 1024" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
# or because it is the entire cluster and can use the zero flag:
# Convert 128m... | XX XX => ... | 00 00
$QEMU_IO -c "write -z $((size)) 1024" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "alloc $size 1024" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 $size 1024" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
echo
echo == unaligned image tail cluster, allocation required ==
# Write beyond backing file must COW
# Backing file: 128m... | XX --
# Active layer: 128m... | -- -- 00 --
CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $((size + 1024))
_make_test_img -b "$TEST_IMG.base" $((size + 2048))
$QEMU_IO -c "write -P 1 $((size)) 512" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z $((size + 1024)) 512" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 1 $((size)) 512" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 $((size + 512)) 1536" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
# Writes at boundaries of (partial) cluster must not lose mid-cluster data
# Backing file: 128m: ... | -- XX
# Active layer: 128m: ... | 00 -- -- 00
CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $((size + 1024))
_make_test_img -b "$TEST_IMG.base" $((size + 2048))
$QEMU_IO -c "write -P 1 $((size + 512)) 512" "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c "write -z $((size)) 512" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 $((size)) 512" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 1 $((size + 512)) 512" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 $((size + 1024)) 1024" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "write -z $((size + 1536)) 512" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 $((size)) 512" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 1 $((size + 512)) 512" "$TEST_IMG" | _filter_qemu_io
$QEMU_IO -c "read -P 0 $((size + 1024)) 1024" "$TEST_IMG" | _filter_qemu_io
$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
# success, all done
echo "*** done"
rm -f $seq.full
status=0
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