linux-ext4 - Re: [RFC PATCH v3 07/26] iomap: don't increase i

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Date: Mon, 19 Feb 2024 09:14:39 +0800
From: Zhang Yi <yi.zhang@...weicloud.com>
To: Dave Chinner <david@...morbit.com>
Cc: Christoph Hellwig <hch@...radead.org>, linux-ext4@...r.kernel.org,
 linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, tytso@....edu, adilger.kernel@...ger.ca,
 jack@...e.cz, ritesh.list@...il.com, djwong@...nel.org, willy@...radead.org,
 zokeefe@...gle.com, yi.zhang@...wei.com, chengzhihao1@...wei.com,
 yukuai3@...wei.com, wangkefeng.wang@...wei.com
Subject: Re: [RFC PATCH v3 07/26] iomap: don't increase i_size if it's not a
 write operation

On 2024/2/19 7:30, Dave Chinner wrote:
> On Sat, Feb 17, 2024 at 04:55:51PM +0800, Zhang Yi wrote:
>> On 2024/2/13 13:46, Christoph Hellwig wrote:
>>> Wouldn't it make more sense to just move the size manipulation to the
>>> write-only code?  An untested version of that is below.  With this
>>
>> Sorry for the late reply and thanks for your suggestion, The reason why
>> I introduced this new helper iomap_write_end_simple() is I don't want to
>> open code __iomap_put_folio() in each caller since corresponding to
>> iomap_write_begin(), it's the responsibility for iomap_write_end_*() to
>> put and unlock folio, so I'd like to keep it in iomap_write_end_*().
> 
> Just because we currently put the folio in iomap_write_end_*(), it
> doesn't mean we must always do it that way.
> 
>> But I don't feel strongly about it, it's also fine by me to just move
>> the size manipulation to the write-only code if you think it's better.
> 
> I agree with Christoph that it's better to move the i_size update
> into iomap_write_iter() than it is to implement a separate write_end
> function that does not update the i_size. The iter functions already
> do work directly on the folio that iomap_write_begin() returns, so
> having them drop the folio when everything is done isn't a huge
> deal...
> 

Sure, I will revise it as you suggested in my next iteration.

Thanks,
Yi.