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Zorro Lang
accf20216c
It's possible for post-eof blocks to end up being used for direct
I/O writes. dio write performs an upfront unwritten extent
allocation, sends the dio and then updates the inode size (if
necessary) on write completion. If a file release occurs while a
file extending dio write is in flight, it is possible to mistake the
post-eof blocks for speculative preallocation and incorrectly
truncate them from the inode. This means that the resulting dio
write completion can discover a hole and allocate new blocks rather
than perform unwritten extent conversion.
A kernel warning can be reproduced by generic/299 on XFS:
XFS: Assertion failed: tp->t_blk_res_used <= tp->t_blk_res, \
file: fs/xfs//xfs_trans.c, line: 309
The root cause is that xfs_free_eofblocks() uses i_size to truncate
post-eof blocks from the inode, but async, file extending direct
writes do not update i_size until write completion, long after inode
locks are dropped. Therefore, xfs_free_eofblocks() effectively
truncates the inode to the incorrect size.
Besides reproduce above kernel warning, the verification of written
data is an important distinction between this test and generic/299.
For cover this filesystem corruption testing, write this new case to
check data integrality manually, not only depend on a kernel
warning.
To increase the test stress of aio-dio-eof-race, add two arguments
to this source code to change the file size will be written.
Signed-off-by: Zorro Lang <zlang@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>
88 lines
2.5 KiB
Bash
Executable File
88 lines
2.5 KiB
Bash
Executable File
#! /bin/bash
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# FS QA Test No. 427
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#
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# Try to trigger a race of free eofblocks and file extending dio writes.
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# A known bug of XFS has been fixed by "e4229d6 xfs: fix eofblocks race
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# with file extending async dio writes"
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#
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#-----------------------------------------------------------------------
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# Copyright (c) 2017 Red Hat Inc. All Rights Reserved.
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#
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# This program is free software; you can redistribute it and/or
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# modify it under the terms of the GNU General Public License as
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# published by the Free Software Foundation.
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#
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# This program is distributed in the hope that it would be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write the Free Software Foundation,
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# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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#-----------------------------------------------------------------------
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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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here=`pwd`
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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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# remove previous $seqres.full before test
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rm -f $seqres.full
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# real QA test starts here
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# Modify as appropriate.
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_supported_fs generic
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_supported_os Linux
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_require_scratch
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_require_test_program "feature"
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_require_aiodio aio-dio-eof-race
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# limit the filesystem size, to save the time of filling filesystem
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_scratch_mkfs_sized $((256 * 1024 * 1024)) >>$seqres.full 2>&1
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_scratch_mount
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# try to write more bytes than filesystem size to fill the filesystem,
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# then remove all these data. If we still can find these stale data in
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# a file' eofblock, then it's a bug
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$XFS_IO_PROG -f -c "pwrite -S 0x55 0 $((256 * 1024 * 1024 * 2))" \
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$SCRATCH_MNT/fillfs-$seq 2>/dev/null
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rm -f $SCRATCH_MNT/fillfs-$seq
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# open & close the file frequently, to trigger xfs_free_eofblocks
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while true; do
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$XFS_IO_PROG -f -c open $SCRATCH_MNT/tst-aio-dio-eof-race.$seq \
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>/dev/null 2>&1
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done &
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open_close_pid=$!
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nr_cpu=`$here/src/feature -o`
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fsize=$((nr_cpu * 10))
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if [ $fsize -gt 200 ]; then
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fsize=200
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fi
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# start a background aio writer, which does several extending loops
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# internally and check data integrality
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$AIO_TEST -s $fsize -b 65536 $SCRATCH_MNT/tst-aio-dio-eof-race.$seq
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status=$?
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kill $open_close_pid
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wait $open_close_pid
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exit
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