On Thu, Jun 29, 2017 at 02:36:41PM +0800, Xiao Yang wrote:
> This test reproduces a race between a direct I/O read and
> a mapped write to a hole in a file. On xfs filesystem, it
> will trigger a BUG_ON(), and this XFS bug has been fixed by:
>
> 04197b3 ("xfs: don't BUG() on mixed direct and mapped I/O")
>
> Signed-off-by: Xiao Yang <yangx.jy@xxxxxxxxxxxxxx>
Thanks for the updated version!
Add linux-xfs list to cc because I noticed an unexpected WARNING when
testing on XFS. Please see below.
> ---
> tests/generic/445 | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++
> tests/generic/445.out | 2 ++
> tests/generic/group | 1 +
> 3 files changed, 92 insertions(+)
> create mode 100755 tests/generic/445
> create mode 100644 tests/generic/445.out
>
> diff --git a/tests/generic/445 b/tests/generic/445
> new file mode 100755
> index 0000000..28dfcbe
> --- /dev/null
> +++ b/tests/generic/445
> @@ -0,0 +1,89 @@
> +#! /bin/bash
> +# FS QA Test No. 445
> +#
> +# Regression test for commit:
> +# 04197b3 ("xfs: don't BUG() on mixed direct and mapped I/O")
> +#
> +# This case tests a race between a direct I/O read and a
> +# mapped write to a hole in a file. On xfs filesystem, it
> +# will trigger a BUG_ON().
> +#
> +#-----------------------------------------------------------------------
> +# Copyright (c) 2017 Fujitsu. All Rights Reserved.
> +# Author: Xiao Yang <yangx.jy@xxxxxxxxxxxxxx>
> +#
> +# 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.
> +#
> +# This program is distributed in the hope that it would 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, write the Free Software Foundation,
> +# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
> +#-----------------------------------------------------------------------
> +
> +seq=`basename $0`
> +seqres=$RESULT_DIR/$seq
> +echo "QA output created by $seq"
> +
> +here=`pwd`
> +tmp=/tmp/$$
> +status=1 # failure is the default!
> +trap "_cleanup; exit \$status" 0 1 2 3 15
> +
> +_cleanup()
> +{
> + rm -rf $tmp.*
> +}
> +
> +# get standard environment and checks
> +. ./common/rc
> +
> +# real QA test starts here
> +_supported_os Linux
> +_require_scratch
> +_require_xfs_io_command "truncate"
> +_require_xfs_io_command "fpunch"
> +
> +rm -f $seqres.full
> +
> +# format and mount
> +_scratch_mkfs > $seqres.full 2>&1
> +_scratch_mount >> $seqres.full 2>&1
> +
> +filesz=$((65536 * 2))
> +
> +# create a test file with a hole
> +$XFS_IO_PROG -f -c "truncate $((filesz * 2))" $SCRATCH_MNT/file >> $seqres.full
> +
> +# run a background dio read to a hole in a loop
> +while true; do
> + $XFS_IO_PROG -d -c "pread 0 $filesz" $SCRATCH_MNT/file > /dev/null 2>&1
> +done &
> +
> +dread_pid=$!
> +
> +# run mapped write to the same hole as dio read
> +for i in `seq 0 999`; do
> + $XFS_IO_PROG -c "mmap 0 $filesz" -c "mwrite 0 $filesz" $SCRATCH_MNT/file \
> + > /dev/null
> + $XFS_IO_PROG -c "fpunch 0 $filesz" $SCRATCH_MNT/file > /dev/null
> +done
> +
> +kill -9 $dread_pid > /dev/null 2>&1
> +wait $dread_pid > /dev/null 2>&1
> +
> +echo "Silence is golden"
> +
> +# check dmesg, filtering out expected XFS warnings about mixed mmap/dio
BTW, I added _scratch_unmount before _check_dmesg, in case umount
triggers other warnings.
> +if [ "$FSTYP" == "xfs" ]; then
> + _check_dmesg _filter_xfs_dmesg
> +else
> + _check_dmesg
> +fi
I hit unexpected warning at fs/iomap.c:766 iomap_dio_actor+0xca/0x370,
which indicates an unknown IOMAP type:
switch (iomap->type) {
case IOMAP_HOLE:
...
case IOMAP_UNWRITTEN:
...
case IOMAP_MAPPED:
...
default:
766 WARN_ON_ONCE(1);
return -EIO;
}
But shouldn't this be fixed by commit a008c31c7ef9 ("iomap_dio_rw: Prevent
reading file data beyond iomap_dio->i_size")? Another code path that
needs fix?
[ 30.894989] ------------[ cut here ]------------
[ 30.895400] WARNING: CPU: 2 PID: 3456 at fs/iomap.c:766 iomap_dio_actor+0xca/0x370
[ 30.896025] Modules linked in: btrfs xor raid6_pq ppdev i2c_piix4 parport_pc sg virtio_balloon parport i2c_core pcspkr nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c sd_mod ata_generic pata_acpi ata_piix virtio_scsi libata virtio_pci virtio_ring 8139too virtio 8139cp serio_raw mii floppy
[ 30.898224] CPU: 2 PID: 3456 Comm: xfs_io Tainted: G W 4.12.0-rc7 #172
[ 30.898851] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2007
[ 30.899348] task: ffff880210e38000 task.stack: ffffc90004a28000
[ 30.899830] RIP: 0010:iomap_dio_actor+0xca/0x370
[ 30.900222] RSP: 0018:ffffc90004a2bc20 EFLAGS: 00010202
[ 30.900656] RAX: 0000000000000002 RBX: ffffc90004a2bcb0 RCX: 00000000006c1000
[ 30.901244] RDX: 00000000000001ff RSI: ffffc90004a2be30 RDI: ffffc90004a2be68
[ 30.901829] RBP: ffffc90004a2bc90 R08: ffffc90004a2bcb0 R09: ffff880213f965a0
[ 30.902428] R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
[ 30.903020] R13: ffffffffa0169b60 R14: ffff880213f965a0 R15: 0000000000000009
[ 30.903604] FS: 00007f7570f77740(0000) GS:ffff88021fd00000(0000) knlGS:0000000000000000
[ 30.904541] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 30.905025] CR2: 00000000006c1000 CR3: 00000002145df000 CR4: 00000000000006e0
[ 30.905614] Call Trace:
[ 30.905820] ? iomap_dio_zero+0x100/0x100
[ 30.906167] iomap_apply+0xa1/0x110
[ 30.906464] iomap_dio_rw+0x20b/0x390
[ 30.906764] ? iomap_dio_zero+0x100/0x100
[ 30.907138] xfs_file_dio_aio_read+0x6e/0xf0 [xfs]
[ 30.907560] xfs_file_read_iter+0xab/0xc0 [xfs]
[ 30.907933] __vfs_read+0xe0/0x150
[ 30.908236] vfs_read+0x8c/0x130
[ 30.908790] SyS_pread64+0x87/0xb0
[ 30.909093] do_syscall_64+0x67/0x150
[ 30.909404] entry_SYSCALL64_slow_path+0x25/0x25
[ 30.909776] RIP: 0033:0x7f7570b59f73
[ 30.910087] RSP: 002b:00007fffd34ce9a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000011
[ 30.910705] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f7570b59f73
[ 30.911297] RDX: 0000000000001000 RSI: 00000000006c1000 RDI: 0000000000000003
[ 30.911875] RBP: 00007fffd34cea60 R08: 0000000000000000 R09: 0000000000000000
[ 30.912473] R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
[ 30.913062] R13: 0000000000020000 R14: 0000000000000000 R15: 0000000000000000
[ 30.913645] Code: e1 48 09 c1 48 85 ca 0f 85 82 02 00 00 0f b7 43 18 66 83 f8 03 0f 84 fb 01 00 00 66 83 f8 04 74 35 66 83 f8 01 0f 84 07 02 00 00 <0f> ff 48 c7 c0 fb ff ff ff 48 8b 4d d0 65 48 33 0c 25 28 00 00
[ 30.915181] ---[ end trace 82f9af72bfb35f21 ]---
Thanks,
Eryu
> +status=$?
> +exit
> diff --git a/tests/generic/445.out b/tests/generic/445.out
> new file mode 100644
> index 0000000..44e55d2
> --- /dev/null
> +++ b/tests/generic/445.out
> @@ -0,0 +1,2 @@
> +QA output created by 445
> +Silence is golden
> diff --git a/tests/generic/group b/tests/generic/group
> index ced111c..39991b1 100644
> --- a/tests/generic/group
> +++ b/tests/generic/group
> @@ -447,3 +447,4 @@
> 442 blockdev
> 443 auto quick rw
> 444 auto quick acl
> +445 auto quick dangerous
> --
> 1.8.3.1
>
>
>
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