linux-kernel - Re: [PATCH] zram: extra zram_get_element call in zram_read_from

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Message-ID: <20231108024839.GF11577@google.com>
Date:   Wed, 8 Nov 2023 11:48:39 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Vasily Averin <vasily.averin@...ux.dev>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Minchan Kim <minchan@...nel.org>, linux-kernel@...r.kernel.org,
        linux-block@...r.kernel.org
Subject: Re: [PATCH] zram: extra zram_get_element call in
 zram_read_from_zspool()

On (23/11/06 23:03), Vasily Averin wrote:
> On 11/6/23 22:55, Vasily Averin wrote:
> > 'element' and 'handle' are union in struct zram_table_entry.
> 
> struct zram_table_entry {
>         union {
>                 unsigned long handle;
>                 unsigned long element;
>         };
> 
> I do not understand the sense of this union.
> From my POV it just makes it harder to check the code because an reviewer doesn't
> expect that the zram element can't be used together.
> Can I remove this union at all and replace zram_get/set_element calls by zram_get/set_handle instead?

I guess it sort of helps API-wise to distinguish zram_handle (allocated
zsmalloc object handle) and zram_element (same-filled entry).

I'll leave it to Minchan to decide.