Re: [PATCH 2/3] generic/470: Test RWF_NOWAIT

[Eryu Guan <eguan@redhat.com>]

On Wed, Nov 29, 2017 at 10:33:57AM -0600, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@suse.com>
> 
> Tests the RWF_NOWAIT flag so the I/O returns immediately with -EAGAIN
> on a new file since it requires block allocation.
> 
> It creates a file, syncs it, and overwrites the file with RWF_NOWAIT.
> This should succeed.
> 
> Finally, read the contents to make sure the overwrite is successful.
> 
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> 
> Changes since v1:
>  - Fix testdir name
>  - use of $XFS_IO_PROG instead of xfs_io
>  - check pwrite accepts -N
> 
> Changes since v2:
>  - corrected test description and improved documentation
>  - new leaner look ;)
>  - rw group
> ---
>  tests/generic/470     | 74 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/470.out | 13 +++++++++
>  tests/generic/group   |  1 +
>  3 files changed, 88 insertions(+)
>  create mode 100755 tests/generic/470
>  create mode 100644 tests/generic/470.out
> 
> diff --git a/tests/generic/470 b/tests/generic/470
> new file mode 100755
> index 00000000..5580718b
> --- /dev/null
> +++ b/tests/generic/470
> @@ -0,0 +1,74 @@
> +#! /bin/bash
> +# FS QA Test No. 470
> +#
> +# write a file with RWF_NOWAIT and it would fail because there are no
> +# blocks allocated. Create a file with direct I/O and re-write it
> +# using RWF_NOWAIT. I/O should finish within 50 microsecods since
> +# block allocations are already performed.
> +#
> +#-----------------------------------------------------------------------
> +# Copyright (c) 2017, SUSE Linux Products.  All Rights Reserved.
> +#
> +# 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!
> +
> +# get standard environment, filters and checks
> +. ./common/rc
> +. ./common/populate
> +. ./common/filter
> +. ./common/attr
> +
> +# real QA test starts here
> +_supported_os Linux
> +_require_odirect
> +_require_test
> +_require_xfs_io_command pwrite -N
> +
> +# Remove reminiscence of previously run tests
> +testdir=$TEST_DIR/$seq
> +if [ -e $testdir ]; then
> +	rm -Rf $testdir
> +fi
> +
> +mkdir $testdir
> +
> +# Create a file with pwrite nowait (will fail with EAGAIN)
> +$XFS_IO_PROG -f -d -c "pwrite -N -V 1 -b 1M 0 1M" $testdir/f1

It's weird that I got "Operation not supported" message here and test
failed as

@@ -1,5 +1,5 @@
 QA output created by 470
-pwrite: Resource temporarily unavailable
+pwrite: Operation not supported
 wrote 8388608/8388608 bytes at offset 0
 XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 RWF_NOWAIT time is within limits.

I was using latest for-next branch of upstream xfsprogs, and a
pre-v4.15-rc1 kernel shipped by Fedora rawhide. A simple test showed:

rm -f /mnt/xfs/testfile
xfs_io -fdc "pwrite -N -V 1 -b 4k 0 4k" /mnt/xfs/testfile
pwrite: Operation not supported

But an strace run showed pwritev2 did -1 and set EAGAIN as errno, but
printed "Operation not supported" as error message:
...
pwritev2(3, [{iov_base="\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315\315"..., iov_len=4096}], 1, 0, RWF_NOWAIT) = -1 EAGAIN (Resource temporarily unavailable)
dup(2)                                  = 4
fcntl(4, F_GETFL)                       = 0x402 (flags O_RDWR|O_APPEND)
openat(AT_FDCWD, "/usr/share/locale/en_US.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/share/locale/en_US.utf8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/share/locale/en_US/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/share/locale/en.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/share/locale/en.utf8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/share/locale/en/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
fstat(4, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 0), ...}) = 0
write(4, "pwrite: Operation not supported\n", 32pwrite: Operation not supported
...

Not sure what happened yet, did I miss anything?

> +
> +# Write the file without nowait
> +$XFS_IO_PROG -f -d -c "pwrite -S 0xaa -W -w -V 1 -b 1M 0 8M" $testdir/f1 | _filter_xfs_io

I think "-w" (fdatasync) can be removed? We already use "-W" (fsync) here.

> +
> +time_taken=`$XFS_IO_PROG -d -c "pwrite -S 0xbb -N -V 1 -b 1M 2M 1M" $testdir/f1 | awk '/^1/ {print $5}'`
> +
> +# RWF_NOWAIT should finish within a short period of time. Anything longer
> +# means it is waiting for something in the kernel which would be a fail.
> +if (( $(echo "$time_taken < 0.05" | bc -l) )); then

Better to describe where does this 0.05 come from.

Thanks,
Eryu

> +	echo "RWF_NOWAIT time is within limits."
> +else
> +	echo "RWF_NOWAIT took $time_taken seconds"
> +fi
> +
> +$XFS_IO_PROG -c "pread -v 0 8M" $testdir/f1 | _filter_xfs_io_unique
> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/generic/470.out b/tests/generic/470.out
> new file mode 100644
> index 00000000..e46622cb
> --- /dev/null
> +++ b/tests/generic/470.out
> @@ -0,0 +1,13 @@
> +QA output created by 470
> +pwrite: Resource temporarily unavailable
> +wrote 8388608/8388608 bytes at offset 0
> +XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> +RWF_NOWAIT time is within limits.
> +00000000:  aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa  ................
> +*
> +00200000:  bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb  ................
> +*
> +00300000:  aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa  ................
> +*
> +read 8388608/8388608 bytes at offset 0
> +XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> diff --git a/tests/generic/group b/tests/generic/group
> index 6c3bb03a..cf8529ea 100644
> --- a/tests/generic/group
> +++ b/tests/generic/group
> @@ -472,3 +472,4 @@
>  467 auto quick exportfs
>  468 shutdown auto quick metadata
>  469 auto quick
> +470 auto quick rw
> -- 
> 2.14.2
>