linux-kernel - Re: Subject: [RFC PATCH v2 0/8] staging: apfs: init APFS filesystem support

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Message-ID: <e6a5a737-ce64-4d31-aeea-2e6190da2ff5@gmail.com>
Date: Thu, 15 May 2025 13:08:19 +0800
From: Nick Chan <towinchenmi@...il.com>
To: Ernesto A. Fernández <ernesto.mnd.fernandez@...il.com>
Cc: Yangtao Li <frank.li@...o.com>, ethan@...ancedwards.com,
 asahi@...ts.linux.dev, brauner@...nel.org, dan.carpenter@...aro.org,
 ernesto@...ellium.com, gargaditya08@...e.com, gregkh@...uxfoundation.org,
 jack@...e.cz, linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-staging@...ts.linux.dev, sven@...npeter.dev, tytso@....edu,
 viro@...iv.linux.org.uk, willy@...radead.org, slava@...eyko.com,
 glaubitz@...sik.fu-berlin.de
Subject: Re: Subject: [RFC PATCH v2 0/8] staging: apfs: init APFS filesystem
 support

Ernesto A. Fernández 於 2025/5/15 凌晨4:19 寫道:
> Hi Nick,
>
> On Tue, May 13, 2025 at 12:13:23PM +0800, Nick Chan wrote:
>> 2. When running Linux on iPhone, iPad, iPod touch, Apple TV (currently there are Apple A7-A11 SoC support in
>> upstream), resizing the main APFS volume is not feasible especially on A11 due to shenanigans with the encrypted
>> data volume. So the safe ish way to store a file system on the disk becomes a using linux-apfs-rw on a (possibly
>> fixed size) volume that only has one file and that file is used as a loopback device.
> That's very interesting. Fragmentation will be brutal after a while though.
> Unless you are patching away the copy-on-write somehow?'
On a fixed size (preallocated size == max size) volume with only a single non-sparse file on it,
copy-on-write should not happen. I believe the xART volume is also the same case with only
one non-sparse file.

[...]
> Ernesto
Nick Chan