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Date: Thu, 4 Apr 2024 17:38:08 +0200 (CEST)
From: "Mkrtchyan, Tigran" <tigran.mkrtchyan@desy.de>
To: Cedric Blancher <cedric.blancher@gmail.com>
Cc: Linux NFS Mailing List <linux-nfs@vger.kernel.org>
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Subject: Re: Linux NFSv4.1 client with Linux NFSv4.1 server, getting block
 size of exported filesystem?
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Thread-Topic: Linux NFSv4.1 client with Linux NFSv4.1 server, getting block size of exported filesystem?
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Date: Thu, 4 Apr 2024 17:38:08 +0200 (CEST)
From: "Mkrtchyan, Tigran" <tigran.mkrtchyan@desy.de>
To: Cedric Blancher <cedric.blancher@gmail.com>
Cc: Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Message-ID: <1246600035.9928999.1712245088183.JavaMail.zimbra@desy.de>
In-Reply-To: <CALXu0UfExxAtoqnFUYbMG=Mpwc0HU3qtb0vuiygXLf6bt=4AaA@mail.gmail.com>
References: <CALXu0UfExxAtoqnFUYbMG=Mpwc0HU3qtb0vuiygXLf6bt=4AaA@mail.gmail.com>
Subject: Re: Linux NFSv4.1 client with Linux NFSv4.1 server, getting block
 size of exported filesystem?
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Thread-Topic: Linux NFSv4.1 client with Linux NFSv4.1 server, getting block size of exported filesystem?
Thread-Index: 9AJK3FzFAnAhFWAD5zkqCvWyDjiytg==

Hi Ced,

no, it can not. However, spec defines two attributes,  maxread and maxwrite, that can indicate
client preferred IO request sizes:

https://datatracker.ietf.org/doc/html/rfc5661#section-5.8.2.20

In pNFS case, an additional layout-specific option, that can override those values.

Best regards,
   Tigran.

----- Original Message -----
> From: "Cedric Blancher" <cedric.blancher@gmail.com>
> To: "Linux NFS Mailing List" <linux-nfs@vger.kernel.org>
> Sent: Wednesday, 3 April, 2024 19:59:16
> Subject: Linux NFSv4.1 client with Linux NFSv4.1 server, getting block size of exported filesystem?

> Good evening!
> 
> Assuming a Linux 6.6 NFSv4.1 client and a Linux 6.6 NFSv4.1 server,
> can the NFSv4.1 client obtain the exact block size of the exported
> filesystem (e.g. ReiserFS, btrfs, ext4, ...) via fstatat()/stat()?
> 
> Ced
> --
> Cedric Blancher <cedric.blancher@gmail.com>
> [https://plus.google.com/u/0/+CedricBlancher/]
> Institute Pasteur

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