linux-kernel - Re: [PATCH 0/7] ext4: Convert truncated extent data to inline data.

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Message-ID: <hcnrjqr4pat6mzp4clxoeu4fuzuldks2qry5ropztfu4makhqe@x5gfsvdgl2ik>
Date: Mon, 6 Jan 2025 16:51:43 +0100
From: Jan Kara <jack@...e.cz>
To: Julian Sun <sunjunchao2870@...il.com>
Cc: linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org, 
	tytso@....edu, adilger.kernel@...ger.ca, jack@...e.cz, boyu.mt@...bao.com, 
	tm@....ma
Subject: Re: [PATCH 0/7] ext4: Convert truncated extent data to inline data.

On Fri 20-12-24 23:16:18, Julian Sun wrote:
> Ext4 provides the feature of storing data inline and automatically 
> converts it to extent data when appropriate. However, files stored 
> as extents cannot be converted back to inline data after truncation, 
> even if the file size allows for inline data storage. 
> This patch set implements the feature to store large truncated files 
> as inline data when suitable, improving disk utilization. 
> Patches 1-3 include some cleanups and fixes. 
> Patches 4-6 refactor the functions responsible for writing inline data, 
> consolidating their logic for better code organization.
> Patch 7 implements the feature of storing truncated files as inline data 
> on the next write operation. 

Thanks for the patches! So ext4 inline data feature is a bit problematic
and has some locking issues in the implementation which we didn't manage to
fix [1]. We are even considering just disabling this feature due to the
complications with it. Hence I don't quite like further complicating this
code by adding possibility to create inline data in an inode after it had
data blocks allocated. That being said I like the preparatory cleanups in
this patch series. These are useful regardless of the feature itself.

								Honza

[1] See our attempts in thread:
https://lore.kernel.org/all/d704ce55-321a-9c1d-1f8b-3360a0fdf978@huawei.com

-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR