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Date:   Fri, 21 Apr 2023 22:10:39 -0700
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Subject: Re: [RFC 8/8] shmem: add support to customize block size on multiple
 PAGE_SIZE
To:     Luis Chamberlain <mcgrof@kernel.org>, hughd@google.com,
        akpm@linux-foundation.org, willy@infradead.org, brauner@kernel.org,
        djwong@kernel.org
Cc:     p.raghav@samsung.com, da.gomez@samsung.com,
        a.manzanares@samsung.com, dave@stgolabs.net, yosryahmed@google.com,
        keescook@chromium.org, hare@suse.de, kbusch@kernel.org,
        patches@lists.linux.dev, linux-block@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
References: <20230421214400.2836131-1-mcgrof@kernel.org>
 <20230421214400.2836131-9-mcgrof@kernel.org>
Content-Language: en-US
From:   Jane Chu <jane.chu@oracle.com>
In-Reply-To: <20230421214400.2836131-9-mcgrof@kernel.org>
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On 4/21/2023 2:44 PM, Luis Chamberlain wrote:
[..]
> +		/*
> +		 * We cap this to allow a block to be at least allowed to
> +		 * be allocated using the buddy allocator. That's MAX_ORDER
> +		 * pages. So 4 MiB on x86_64.

8 MiB? since MAX_ORDER is 11.

> +		 */
> +		if (ctx->blocksize > (1 << (MAX_ORDER + PAGE_SHIFT)))
> +			goto bad_value; > +
> +		/* The blocksize must be a multiple of the page size so must be aligned */
> +		if (!PAGE_ALIGNED(ctx->blocksize))
> +			goto bad_value;
> +		break;
>   	}
>   	return 0;

-jane