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From:   "Benjamin Coddington" <bcodding@redhat.com>
To:     trondmy@kernel.org
Cc:     linux-nfs@vger.kernel.org
Subject: Re: [PATCH v7 04/21] NFS: Calculate page offsets algorithmically
Date:   Thu, 24 Feb 2022 09:15:54 -0500
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On 23 Feb 2022, at 16:12, trondmy@kernel.org wrote:

> From: Trond Myklebust <trond.myklebust@hammerspace.com>
>
> Instead of relying on counting the page offsets as we walk through the
> page cache, switch to calculating them algorithmically.
>
> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
> ---
>  fs/nfs/dir.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
> index 8f17aaebcd77..f2258e926df2 100644
> --- a/fs/nfs/dir.c
> +++ b/fs/nfs/dir.c
> @@ -248,17 +248,20 @@ static const char *nfs_readdir_copy_name(const 
> char *name, unsigned int len)
>  	return ret;
>  }
>
> +static size_t nfs_readdir_array_maxentries(void)
> +{
> +	return (PAGE_SIZE - sizeof(struct nfs_cache_array)) /
> +	       sizeof(struct nfs_cache_array_entry);
> +}
> +

Why the choice to use a runtime function call rather than the compiler's
calculation?  I suspect that the end result is the same, as the compiler
will optimize it away, but I'm curious if there's a good reason for 
this.

Ben