From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7BD4E2248A8 for ; Mon, 13 Apr 2026 19:22:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776108146; cv=none; b=C4DXMN568TxaPdWhxjn7R5Az9jfyCU8v+6KpiZwqRvOU1Y/Nh7u92PIyT/GEFRzmKY6xq6A9XD/yfMN18oZvImG8VbbXlSZmHJFP1kV48Iv2QNS1MQUqKVVGLtQZ6pIqnwYaAd3t8MO+kOWt9Pkh+0+od3IqPAAp94QESWq58Do= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776108146; c=relaxed/simple; bh=6yt3xOr8y7pXd+uABsqgDirlTPZCXO50u6hKg963WuY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=JhlC0jKE0iKQA0mk1AZM3zuGeq3vHbDibT9osQ+fclur0ZaOi3zXSgt8lP5aphot0Exs5lM3/7aKF7Fmd+vYuMU0zCwVpdQVFR/Ia4tBtF43CzX/J212oMvMjevJWkByg7Grlnx71LFiwE4gTa2Us6rml81Qkl1Qhay66075fp0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Mx8jW+db; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Mx8jW+db" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8D428C2BCAF; Mon, 13 Apr 2026 19:22:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776108146; bh=6yt3xOr8y7pXd+uABsqgDirlTPZCXO50u6hKg963WuY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Mx8jW+db/w3gjd7l4chTJScvVhQ72tI2b62f2QcBEtBCtvu9rfJgxGi0mBdEpimnC vJn3xXR5/Tqzl5DwtH6Ilpi53r0X8VQYJ89nheC11P/wcIPeGbSglT50sgYmZXAgYN ZKMIR7gWEVqLHbIhHkezkfXkmpCwngsi7BFgPFdpBfZvCB/A3jrn/9BFJYJMB0sx5E um3SGeUcF/gAVZJ8079z5w6BICVGzOD2QKcXWckfwG/+/LVSaIjBVbKc21lwws+Who uJjAOyf0kOdlI497vNftc5RIeUeUOpUrczMcBruSI8LQXQ739wMrtPj3NPhkdYcmV5 3TpUzHIqY/gtA== Message-ID: Date: Mon, 13 Apr 2026 21:22:20 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] f2fs: do not support mmap write for large folio To: Jaegeuk Kim Cc: Christoph Hellwig , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20260406154940.2407853-1-jaegeuk@kernel.org> <2aee26dd-703b-47c4-9210-f70ffa6faf09@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/8/26 20:08, Jaegeuk Kim wrote: > On 04/08, David Hildenbrand (Arm) wrote: >> On 4/8/26 07:03, Christoph Hellwig wrote: >>> >>> In general spelling such basic out in the commit log, and even comments >>> is really helpful. I'm curious how this works, though - by the time >>> you read a large folio you don't know if it will ever be written to. >> >> Why are only large folios supported for read? >> >> Where is that allocation logic and how can that path even be triggered? >> >> Also, usually we check for large folios by testing the actual folio, not >> whether the mapping supports them? > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v7.0-rc7&id=05e65c14ea59a401cec4284e9d612f9d5dc1b3f8 > > Currently I think it's simple to check the mapping in our case. Thanks for the pointer. So you are adding code for something that is impossible to be reached. Reading the other discussions, I agree that this should be flagged clearer as an assertion, and not a fix. I'll let maintainers decide whether that is a assertion we should add :) -- Cheers, David