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Date: Tue, 11 Jun 2024 18:13:11 +0200
From: Christoph Hellwig <hch@lst.de>
To: Shaun Tancheff <shaun.tancheff@hpe.com>
Cc: Christoph Hellwig <hch@lst.de>,
	Trond Myklebust <trond.myklebust@hammerspace.com>,
	Anna Schumaker <anna@kernel.org>,
	Matthew Wilcox <willy@infradead.org>, linux-nfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 1/2] filemap: Convert generic_perform_write() to
 support large folios
Message-ID: <20240611161311.GA12257@lst.de>
References: <20240527163616.1135968-1-hch@lst.de> <20240527163616.1135968-2-hch@lst.de> <8e23be47-e542-4bb8-8da7-da7801c98e42@hpe.com>
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On Tue, Jun 11, 2024 at 05:47:12PM +0700, Shaun Tancheff wrote:
>>   	const struct address_space_operations *a_ops = mapping->a_ops;
>> +	size_t chunk = mapping_max_folio_size(mapping);
>
> Better to default chunk to PAGE_SIZE for backward compat
> +       size_t chunk = PAGE_SIZE;
>
>>   	long status = 0;
>>   	ssize_t written = 0;
>>   
>
> Have fs opt in to large folio support:
>
> +       if (mapping_large_folio_support(mapping))
> +               chunk = PAGE_SIZE << MAX_PAGECACHE_ORDER;

I don't think you've actually read the code, have you?