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Filipe Manana
7931e0696c
Test that if we write into an unwritten extent of a file when there is no more space left to allocate in the filesystem and then snapshot the file's subvolume, after a clean shutdown the data was not lost. This test is motivated by a bug found by Robbie Ko for which there is a fix whose patch title is: "Btrfs: fix unexpected failure of nocow buffered writes after snapshotting when low on space" Reported-by: Robbie Ko <robbieko@synology.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: Eryu Guan <guaneryu@gmail.com> Signed-off-by: Eryu Guan <guaneryu@gmail.com>
76 lines
2.4 KiB
Bash
Executable File
76 lines
2.4 KiB
Bash
Executable File
#! /bin/bash
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# SPDX-License-Identifier: GPL-2.0
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# Copyright (C) 2018 SUSE Linux Products GmbH. All Rights Reserved.
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#
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# FS QA Test No. 170
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#
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# Test that if we write into an unwritten extent of a file when there is no
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# more space left to allocate in the filesystem and then snapshot the file's
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# subvolume, after a clean shutdown the data was not lost.
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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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cd /
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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_xfs_io_command "falloc" "-k"
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rm -f $seqres.full
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# Use a fixed size filesystem so that we can precisely fill the data block group
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# mkfs.btrfs creates and allocate all unused space for a new data block group.
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# It's important to not use the mixed block groups feature as well because we
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# later want to not have more space available for allocating data extents but
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# still have enough metadata space free for creating the snapshot.
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fs_size=$((2 * 1024 * 1024 * 1024)) # 2Gb
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_scratch_mkfs_sized $fs_size >>$seqres.full 2>&1
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# Mount without space cache so that we can precisely fill all data space and
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# unallocated space later (space cache v1 uses data block groups).
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_scratch_mount "-o nospace_cache"
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# Create our test file and allocate 1826.25Mb of space for it.
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# This will exhaust the existing data block group and all unallocated space on
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# this small fileystem (2Gb).
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$XFS_IO_PROG -f -c "falloc -k 0 1914961920" $SCRATCH_MNT/foobar
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# Write some data to the file and check its digest. This write will result in a
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# NOCOW write because there's no more space available to allocate and the file
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# has preallocated (unwritten) extents.
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$XFS_IO_PROG -c "pwrite -S 0xea -b 128K 0 128K" $SCRATCH_MNT/foobar | _filter_xfs_io
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echo "File digest after write:"
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md5sum $SCRATCH_MNT/foobar | _filter_scratch
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# Create a snapshot of the subvolume where our file is.
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$BTRFS_UTIL_PROG subvolume snapshot -r $SCRATCH_MNT $SCRATCH_MNT/snap 2>&1 \
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| _filter_scratch
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# Cleanly unmount the filesystem.
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_scratch_unmount
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# Mount the filesystem again and verify the file has the same data it had before
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# we unmounted the filesystem (same digest).
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_scratch_mount
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echo "File digest after mounting the filesystem again:"
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md5sum $SCRATCH_MNT/foobar | _filter_scratch
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status=0
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exit
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