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Date:   Sun, 5 May 2019 19:49:58 -0700
From:   Matthew Wilcox <willy@infradead.org>
To:     Tamir Carmeli <carmeli.tamir@gmail.com>
Cc:     viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] Use list.h instead of file_system_type next
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On Sun, May 05, 2019 at 09:25:21PM +0300, Tamir Carmeli wrote:
> I just found it weird that there is a proprietary implementation of a
> linked list while surely the kernel already offers well established
> data structures.

It's a singly linked list rather than a doubly linked list.

> IMO, the current code is a bit hard to understand, especially the
> addition of a new struct to the list in the line "*p = fs" after
> find_filesystem returned the last member.
> Correct, I'm not familiar with all the use cases of the code.

It looks like a fairly standard implementation of a singly-linked 
list in C to me.

> I'm not sure that XArray is a good choice since there is no notion of
> an index attached to the pointer, it's really just a linked list of
> pointers.

You don't need to attach an index to the pointer; you can just use
xa_alloc() to store it at the first available index.