mirror of
https://github.com/linux-apfs/apfstests.git
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Dave Chinner
1ff4192932
Fully scripted conversion, see script in initial SPDX license commit message. Signed-off-by: Dave Chinner <dchinner@redhat.com>
118 lines
3.1 KiB
Bash
Executable File
118 lines
3.1 KiB
Bash
Executable File
#! /bin/bash
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# SPDX-License-Identifier: GPL-2.0
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# Copyright (C) 2014 SUSE Linux Products GmbH. All Rights Reserved.
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#
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# FSQA Test No. 081
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#
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# Regression test for a btrfs clone ioctl issue where races between
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# a clone operation and concurrent target file reads would result in
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# leaving stale data in the page cache. After the clone operation
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# finished, reading from the clone target file would return the old
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# and no longer valid data. This affected only buffered reads (i.e.
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# didn't affect direct IO reads).
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#
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# This issue was fixed by the following linux kernel patch:
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#
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# Btrfs: ensure readers see new data after a clone operation
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# (commit c125b8bff1d9f6c8c91ce4eb8bd5616058c7d510)
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#
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seq=`basename $0`
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seqres=$RESULT_DIR/$seq
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echo "QA output created by $seq"
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tmp=/tmp/$$
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status=1 # failure is the default!
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trap "_cleanup; exit \$status" 0 1 2 3 15
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_cleanup()
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{
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rm -f $tmp.*
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}
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# get standard environment, filters and checks
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. ./common/rc
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. ./common/filter
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# real QA test starts here
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_supported_fs btrfs
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_supported_os Linux
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_require_scratch
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_require_cloner
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rm -f $seqres.full
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num_extents=100
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extent_size=8192
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create_source_file()
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{
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name=$1
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# Create a file with $num_extents extents, each with a size of
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# $extent_size bytes.
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touch $SCRATCH_MNT/$name
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for ((i = 0; i < $num_extents; i++)); do
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off=$((i * $extent_size))
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$XFS_IO_PROG \
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-c "pwrite -S $i -b $extent_size $off $extent_size" \
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-c "fsync" $SCRATCH_MNT/$name | _filter_xfs_io
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done
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}
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create_target_file()
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{
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name=$1
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file_size=$(($num_extents * $extent_size))
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$XFS_IO_PROG -f -c "pwrite -S 0xff 0 $file_size" \
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-c "fsync" $SCRATCH_MNT/$name | _filter_xfs_io
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}
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reader_loop()
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{
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name=$1
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while true; do
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cat $SCRATCH_MNT/$name > /dev/null
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done
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}
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_scratch_mkfs >>$seqres.full 2>&1
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_scratch_mount
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echo "Creating source file..."
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create_source_file "foo"
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echo "Creating target file..."
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create_target_file "bar"
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reader_loop "bar" &
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reader_pid=$!
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$CLONER_PROG -s 0 -d 0 -l $(($num_extents * $extent_size)) \
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$SCRATCH_MNT/foo $SCRATCH_MNT/bar
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kill $reader_pid > /dev/null 2>&1
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# Now both foo and bar should have exactly the same content.
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# This didn't use to be the case before the btrfs kernel fix mentioned
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# above. The clone ioctl was racy, as it removed bar's pages from the
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# page cache and only after it would update bar's metadata to point to
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# the same extents that foo's metadata points to - and this was done in
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# an unprotected way, so that a file read request done right after the
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# clone ioctl removed the pages from the page cache and before it updated
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# bar's metadata, would result in populating the page cache with stale
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# data. Therefore a file read after the clone operation finished would
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# not get the cloned data but it would get instead the old and no longer
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# valid data.
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echo "Verifying file digests after cloning"
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md5sum $SCRATCH_MNT/foo | _filter_scratch
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md5sum $SCRATCH_MNT/bar | _filter_scratch
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# Validate the content of bar still matches foo's content even after
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# clearing all of bar's data from the page cache.
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_scratch_cycle_mount
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echo "Verifying target file digest after umount + mount"
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md5sum $SCRATCH_MNT/bar | _filter_scratch
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status=0
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exit
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