[PATCH] generic/471: adapt test when running on btrfs to avoid failure on RWF_NOWAIT write

[PATCH] generic/471: adapt test when running on btrfs to avoid failure on RWF_NOWAIT write

[fdmanana]

From: Filipe Manana <fdmanana@suse.com>

This test currently always fails on btrfs:

generic/471 2s ... - output mismatch (see ...results//generic/471.out.bad)
    --- tests/generic/471.out   2020-06-10 19:29:03.850519863 +0100
    +++ /home/fdmanana/git/hub/xfstests/results//generic/471.out.bad   ...
    @@ -2,12 +2,10 @@
     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.
    +pwrite: Resource temporarily unavailable
    +(standard_in) 1: syntax error
    +RWF_NOWAIT took  seconds

This is because btrfs is a COW filesystem and an attempt to write into a
previously written file range allocating a new extent (or multiple).
The only exceptions are when attempting to write to a file range with a
preallocated/unwritten extent or when writing to a NOCOW file that has
extents allocated in the target range already.

The test currently expects that writing into a previously written file
range succeeds, but that is not true on btrfs since we are not dealing
with a NOCOW file. So to make the test pass on btrfs, set the NOCOW bit
on the file when the filesystem is btrfs.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
---
 tests/generic/471 | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tests/generic/471 b/tests/generic/471
index 7513f023..e9856b52 100755
--- a/tests/generic/471
+++ b/tests/generic/471
@@ -37,6 +37,17 @@ fi
 
 mkdir $testdir
 
+# Btrfs is a COW filesystem, so a RWF_NOWAIT write will always fail with -EAGAIN
+# when writing to a file range except if it's a NOCOW file and an extent for the
+# range already exists or if it's a COW file and preallocated/unwritten extent
+# exists in the target range. So to make sure that the last write succeeds on
+# all filesystems, use a NOCOW file on btrfs.
+if [ $FSTYP == "btrfs" ]; then
+	_require_chattr C
+	touch $testdir/f1
+	$CHATTR_PROG +C $testdir/f1
+fi
+
 # 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
 
-- 
2.26.2

Re: [PATCH] generic/471: adapt test when running on btrfs to avoid failure on RWF_NOWAIT write

[Josef Bacik]

On 6/12/20 10:06 AM, fdmanana@kernel.org wrote:
> From: Filipe Manana <fdmanana@suse.com>
> 
> This test currently always fails on btrfs:
> 
> generic/471 2s ... - output mismatch (see ...results//generic/471.out.bad)
>      --- tests/generic/471.out   2020-06-10 19:29:03.850519863 +0100
>      +++ /home/fdmanana/git/hub/xfstests/results//generic/471.out.bad   ...
>      @@ -2,12 +2,10 @@
>       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.
>      +pwrite: Resource temporarily unavailable
>      +(standard_in) 1: syntax error
>      +RWF_NOWAIT took  seconds
> 
> This is because btrfs is a COW filesystem and an attempt to write into a
> previously written file range allocating a new extent (or multiple).
> The only exceptions are when attempting to write to a file range with a
> preallocated/unwritten extent or when writing to a NOCOW file that has
> extents allocated in the target range already.
> 
> The test currently expects that writing into a previously written file
> range succeeds, but that is not true on btrfs since we are not dealing
> with a NOCOW file. So to make the test pass on btrfs, set the NOCOW bit
> on the file when the filesystem is btrfs.
> 
> Signed-off-by: Filipe Manana <fdmanana@suse.com>

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Thanks,

Josef

Re: [PATCH] generic/471: adapt test when running on btrfs to avoid failure on RWF_NOWAIT write

[Qu Wenruo]

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On 2020/6/12 下午10:06, fdmanana@kernel.org wrote:
> From: Filipe Manana <fdmanana@suse.com>
> 
> This test currently always fails on btrfs:
> 
> generic/471 2s ... - output mismatch (see ...results//generic/471.out.bad)
>     --- tests/generic/471.out   2020-06-10 19:29:03.850519863 +0100
>     +++ /home/fdmanana/git/hub/xfstests/results//generic/471.out.bad   ...
>     @@ -2,12 +2,10 @@
>      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.
>     +pwrite: Resource temporarily unavailable
>     +(standard_in) 1: syntax error
>     +RWF_NOWAIT took  seconds
> 
> This is because btrfs is a COW filesystem and an attempt to write into a
> previously written file range allocating a new extent (or multiple).
> The only exceptions are when attempting to write to a file range with a
> preallocated/unwritten extent or when writing to a NOCOW file that has
> extents allocated in the target range already.
> 
> The test currently expects that writing into a previously written file
> range succeeds, but that is not true on btrfs since we are not dealing
> with a NOCOW file. So to make the test pass on btrfs, set the NOCOW bit
> on the file when the filesystem is btrfs.

Completely agree with the point for btrfs.

> 
> Signed-off-by: Filipe Manana <fdmanana@suse.com>
> ---
>  tests/generic/471 | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/tests/generic/471 b/tests/generic/471
> index 7513f023..e9856b52 100755
> --- a/tests/generic/471
> +++ b/tests/generic/471
> @@ -37,6 +37,17 @@ fi
>  
>  mkdir $testdir
>  
> +# Btrfs is a COW filesystem, so a RWF_NOWAIT write will always fail with -EAGAIN
> +# when writing to a file range except if it's a NOCOW file and an extent for the
> +# range already exists or if it's a COW file and preallocated/unwritten extent
> +# exists in the target range. So to make sure that the last write succeeds on
> +# all filesystems, use a NOCOW file on btrfs.
> +if [ $FSTYP == "btrfs" ]; then

Although I'm not sure if really only specific to btrfs.
XFS has its always_cow sysfs interface to make data write to always do
COW, just like what btrfs do by default.

Thus I believe this may be needed for all fses, and just ignore the
error if the fs doesn't support COW.

Thanks,
Qu

> +	_require_chattr C
> +	touch $testdir/f1
> +	$CHATTR_PROG +C $testdir/f1
> +fi
> +
>  # 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
>  
> 


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Re: [PATCH] generic/471: adapt test when running on btrfs to avoid failure on RWF_NOWAIT write

[Filipe Manana]

On Sun, Jun 14, 2020 at 6:14 AM Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:
>
>
>
> On 2020/6/12 下午10:06, fdmanana@kernel.org wrote:
> > From: Filipe Manana <fdmanana@suse.com>
> >
> > This test currently always fails on btrfs:
> >
> > generic/471 2s ... - output mismatch (see ...results//generic/471.out.bad)
> >     --- tests/generic/471.out   2020-06-10 19:29:03.850519863 +0100
> >     +++ /home/fdmanana/git/hub/xfstests/results//generic/471.out.bad   ...
> >     @@ -2,12 +2,10 @@
> >      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.
> >     +pwrite: Resource temporarily unavailable
> >     +(standard_in) 1: syntax error
> >     +RWF_NOWAIT took  seconds
> >
> > This is because btrfs is a COW filesystem and an attempt to write into a
> > previously written file range allocating a new extent (or multiple).
> > The only exceptions are when attempting to write to a file range with a
> > preallocated/unwritten extent or when writing to a NOCOW file that has
> > extents allocated in the target range already.
> >
> > The test currently expects that writing into a previously written file
> > range succeeds, but that is not true on btrfs since we are not dealing
> > with a NOCOW file. So to make the test pass on btrfs, set the NOCOW bit
> > on the file when the filesystem is btrfs.
>
> Completely agree with the point for btrfs.
>
> >
> > Signed-off-by: Filipe Manana <fdmanana@suse.com>
> > ---
> >  tests/generic/471 | 11 +++++++++++
> >  1 file changed, 11 insertions(+)
> >
> > diff --git a/tests/generic/471 b/tests/generic/471
> > index 7513f023..e9856b52 100755
> > --- a/tests/generic/471
> > +++ b/tests/generic/471
> > @@ -37,6 +37,17 @@ fi
> >
> >  mkdir $testdir
> >
> > +# Btrfs is a COW filesystem, so a RWF_NOWAIT write will always fail with -EAGAIN
> > +# when writing to a file range except if it's a NOCOW file and an extent for the
> > +# range already exists or if it's a COW file and preallocated/unwritten extent
> > +# exists in the target range. So to make sure that the last write succeeds on
> > +# all filesystems, use a NOCOW file on btrfs.
> > +if [ $FSTYP == "btrfs" ]; then
>
> Although I'm not sure if really only specific to btrfs.
> XFS has its always_cow sysfs interface to make data write to always do
> COW, just like what btrfs do by default.
>
> Thus I believe this may be needed for all fses, and just ignore the
> error if the fs doesn't support COW.

I don't understand your point.
If that flag is enabled on xfs (iirc it's a debug flag), the test
would fail on xfs even if we attempt chattr +C (afaics xfs doesn't
support +C).
So I don't see the benefit of always doing it.

Thanks.


>
> Thanks,
> Qu
>
> > +     _require_chattr C
> > +     touch $testdir/f1
> > +     $CHATTR_PROG +C $testdir/f1
> > +fi
> > +
> >  # 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
> >
> >
>

Re: [PATCH] generic/471: adapt test when running on btrfs to avoid failure on RWF_NOWAIT write

[Qu Wenruo]

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On 2020/6/15 下午7:53, Filipe Manana wrote:
> On Sun, Jun 14, 2020 at 6:14 AM Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:
>>
>>
>>
>> On 2020/6/12 下午10:06, fdmanana@kernel.org wrote:
>>> From: Filipe Manana <fdmanana@suse.com>
>>>
>>> This test currently always fails on btrfs:
>>>
>>> generic/471 2s ... - output mismatch (see ...results//generic/471.out.bad)
>>>     --- tests/generic/471.out   2020-06-10 19:29:03.850519863 +0100
>>>     +++ /home/fdmanana/git/hub/xfstests/results//generic/471.out.bad   ...
>>>     @@ -2,12 +2,10 @@
>>>      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.
>>>     +pwrite: Resource temporarily unavailable
>>>     +(standard_in) 1: syntax error
>>>     +RWF_NOWAIT took  seconds
>>>
>>> This is because btrfs is a COW filesystem and an attempt to write into a
>>> previously written file range allocating a new extent (or multiple).
>>> The only exceptions are when attempting to write to a file range with a
>>> preallocated/unwritten extent or when writing to a NOCOW file that has
>>> extents allocated in the target range already.
>>>
>>> The test currently expects that writing into a previously written file
>>> range succeeds, but that is not true on btrfs since we are not dealing
>>> with a NOCOW file. So to make the test pass on btrfs, set the NOCOW bit
>>> on the file when the filesystem is btrfs.
>>
>> Completely agree with the point for btrfs.
>>
>>>
>>> Signed-off-by: Filipe Manana <fdmanana@suse.com>
>>> ---
>>>  tests/generic/471 | 11 +++++++++++
>>>  1 file changed, 11 insertions(+)
>>>
>>> diff --git a/tests/generic/471 b/tests/generic/471
>>> index 7513f023..e9856b52 100755
>>> --- a/tests/generic/471
>>> +++ b/tests/generic/471
>>> @@ -37,6 +37,17 @@ fi
>>>
>>>  mkdir $testdir
>>>
>>> +# Btrfs is a COW filesystem, so a RWF_NOWAIT write will always fail with -EAGAIN
>>> +# when writing to a file range except if it's a NOCOW file and an extent for the
>>> +# range already exists or if it's a COW file and preallocated/unwritten extent
>>> +# exists in the target range. So to make sure that the last write succeeds on
>>> +# all filesystems, use a NOCOW file on btrfs.
>>> +if [ $FSTYP == "btrfs" ]; then
>>
>> Although I'm not sure if really only specific to btrfs.
>> XFS has its always_cow sysfs interface to make data write to always do
>> COW, just like what btrfs do by default.
>>
>> Thus I believe this may be needed for all fses, and just ignore the
>> error if the fs doesn't support COW.
> 
> I don't understand your point.
> If that flag is enabled on xfs (iirc it's a debug flag), the test
> would fail on xfs even if we attempt chattr +C (afaics xfs doesn't
> support +C).

Oh, my fault. Didn't know that xfs won't support chattr +C.

Then forget the comment.

Thanks,
Qu
> So I don't see the benefit of always doing it.
> 
> Thanks.
> 
> 
>>
>> Thanks,
>> Qu
>>
>>> +     _require_chattr C
>>> +     touch $testdir/f1
>>> +     $CHATTR_PROG +C $testdir/f1
>>> +fi
>>> +
>>>  # 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
>>>
>>>
>>


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