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Date: Thu, 11 Mar 2021 16:08:17 +0100
From: Christoph Hellwig <hch@lst.de>
To: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: libc-alpha@sourceware.org, Florian Weimer <fweimer@redhat.com>
Subject: Re: [RFC] io: Return UNSUPPORTED if filesystem do not support 64
 bit timestamps
Message-ID: <20210311150817.GA22422@lst.de>
References: <20210311123557.3486677-1-adhemerval.zanella@linaro.org>
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On Thu, Mar 11, 2021 at 09:35:57AM -0300, Adhemerval Zanella via Libc-alpha wrote:
> +bool
> +support_path_support_time64 (const char *path)
> +{
> +#ifdef __linux__
> +  struct statfs64 fs;
> +  if (statfs64 (path, &fs) < 0)
> +    FAIL_EXIT1 ("statfs64 (\"%s\"): %m", path);
> +  /* Kernel silent truncate metadata timestamps on some version.  */
> +  return ! (fs.f_type == XFS_SUPER_MAGIC);

Please check for the actual truncation, as XFS does not always do
this based on the exact on-disk format revision.