linux-kernel - Re: [PATCH v3 0/4] allow partial folio write with iomap_folio

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Message-ID: <aKwuJptHVsx-Ed82@infradead.org>
Date: Mon, 25 Aug 2025 02:34:30 -0700
From: Christoph Hellwig <hch@...radead.org>
To: alexjlzheng@...il.com
Cc: brauner@...nel.org, djwong@...nel.org, linux-xfs@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	yi.zhang@...wei.com, Jinliang Zheng <alexjlzheng@...cent.com>
Subject: Re: [PATCH v3 0/4] allow partial folio write with iomap_folio_state

On Tue, Aug 12, 2025 at 05:15:34PM +0800, alexjlzheng@...il.com wrote:
> From: Jinliang Zheng <alexjlzheng@...cent.com>
> 
> With iomap_folio_state, we can identify uptodate states at the block
> level, and a read_folio reading can correctly handle partially
> uptodate folios.
> 
> Therefore, when a partial write occurs, accept the block-aligned
> partial write instead of rejecting the entire write.
> 
> For example, suppose a folio is 2MB, blocksize is 4kB, and the copied
> bytes are 2MB-3kB.

I'd still love to see some explanation of why you are doing this.
Do you have a workload that actually hits this regularly, and where
it makes a difference.  Can you provide numbers to quantify them?