Re: [PATCH V2] nfs(5): Update rsize/wsize options

[Steve Dickson <steved@redhat.com>]

On 11/20/24 2:57 AM, Cedric Blancher wrote:
> On Tue, 19 Nov 2024 at 18:07, Steve Dickson <steved@redhat.com> wrote:
>>
>> From: Seiichi Ikarashi <s.ikarashi@fujitsu.com>
>>
>> The rsize/wsize values are not multiples of 1024 but multiples of the
>> system's page size or powers of 2 if < system's page size as defined
>> in fs/nfs/internal.h:nfs_io_size().
>>
>> Signed-off-by: Steve Dickson <steved@redhat.com>
> 
> REJECT. 
You mean NACK! :-)

> As discussed, this is the WRONG approach. The pagesize is not
> not easily determinable (/bin/pagesize not even being part of the
> default install), and the page size is flexible on many architectures.
Yes... /bin/pagesize is not needed only getconf PAGESIZE is which
is in all default installs.

> rsize/wsize depending on the page size makes this option non portable
> across platforms, or even same platforms with different default
> pagesize settings.
"rsize/wsize depending on the page size" is a kernel thing...
Nothing nfs-utils can do about it but accurately document
what is happening.

> In real life, this can prevent puppet from working for NFS root, if
> NFS root needs rsize/wsize, and someone switches the default page
> size.
Why is puppet evening messing with rsize/wsize? Just let the
kernel do the right thing...

> 
> I thought the correct fix would be to fix the NFS client to count in
> kbytes as documented, and round up/down to the pagesize.
Again this is a kernel thing... Patches are welcomed!

steved.

> 
> Ced
> 
>> ---
>>   utils/mount/nfs.man | 24 +++++++++++++++---------
>>   1 file changed, 15 insertions(+), 9 deletions(-)
>>
>> V2: Replaced PAGE_SIZE with "system's page size"
>>
>> diff --git a/utils/mount/nfs.man b/utils/mount/nfs.man
>> index 233a7177..eab4692a 100644
>> --- a/utils/mount/nfs.man
>> +++ b/utils/mount/nfs.man
>> @@ -215,15 +215,18 @@ or smaller than the
>>   setting. The largest read payload supported by the Linux NFS client
>>   is 1,048,576 bytes (one megabyte).
>>   .IP
>> -The
>> +The allowed
>>   .B rsize
>> -value is a positive integral multiple of 1024.
>> +value is a positive integral multiple of
>> +system's page size
>> +or a power of two if it is less than
>> +system's page size.
>>   Specified
>>   .B rsize
>>   values lower than 1024 are replaced with 4096; values larger than
>>   1048576 are replaced with 1048576. If a specified value is within the supported
>> -range but not a multiple of 1024, it is rounded down to the nearest
>> -multiple of 1024.
>> +range but not such an allowed value, it is rounded down to the nearest
>> +allowed value.
>>   .IP
>>   If an
>>   .B rsize
>> @@ -257,16 +260,19 @@ setting. The largest write payload supported by the Linux NFS client
>>   is 1,048,576 bytes (one megabyte).
>>   .IP
>>   Similar to
>> -.B rsize
>> -, the
>> +.BR rsize ,
>> +the allowed
>>   .B wsize
>> -value is a positive integral multiple of 1024.
>> +value is a positive integral multiple of
>> +system's page size
>> +or a power of two if it is less than
>> +system's page size.
>>   Specified
>>   .B wsize
>>   values lower than 1024 are replaced with 4096; values larger than
>>   1048576 are replaced with 1048576. If a specified value is within the supported
>> -range but not a multiple of 1024, it is rounded down to the nearest
>> -multiple of 1024.
>> +range but not such an allowed value, it is rounded down to the nearest
>> +allowed value.
>>   .IP
>>   If a
>>   .B wsize
>> --
>> 2.47.0
>>
>>
> 
>