linux-kernel - Re: [PATCH 4/6] Xarray: skip unneeded xas_store() and xas_clear_mark() in __xa

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Message-ID: <ZyT7qRhtqGDe_AuO@casper.infradead.org>
Date: Fri, 1 Nov 2024 16:02:49 +0000
From: Matthew Wilcox <willy@...radead.org>
To: Kemeng Shi <shikemeng@...weicloud.com>
Cc: akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 4/6] Xarray: skip unneeded xas_store() and
 xas_clear_mark() in __xa_alloc()

On Fri, Nov 01, 2024 at 11:50:26PM +0800, Kemeng Shi wrote:
> If xas_find_marked() failed, there is no need to call xas_store() and
> xas_clear_mark(). Just call xas_store() and xas_clear_mark() if
> xas_find_marked() succeed.

No.  The point of the xas interfaces is that they turn into no-ops once
an error has occurred.

> -		else
> +		else {
>  			*id = xas.xa_index;
> -		xas_store(&xas, entry);
> -		xas_clear_mark(&xas, XA_FREE_MARK);
> +			xas_store(&xas, entry);
> +			xas_clear_mark(&xas, XA_FREE_MARK);
> +		}
>  	} while (__xas_nomem(&xas, gfp));
>  
>  	return xas_error(&xas);
> -- 
> 2.30.0
>