From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (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 C5A4233ADA0; Tue, 24 Feb 2026 14:01:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.95.11.211 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771941682; cv=none; b=lCqYllf2ab1RnB156G8M+Mot4uU69/Qf3IvsboEjteLsz+fhMhClLYpirJuLb+zy3wRkAr2Rzm0189kTBjQxLqFPAB5Gl/FUF40XD+tA680vfj6tQUXYAhuHto09NZqy3orftDrnZ63mqEugvyfXt9d2iboLOui/GULtj2uWu+k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771941682; c=relaxed/simple; bh=sBsOQPpLrZzU5mkoq5b6thjhGKFDFhe9Nt+bbi+6LWE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=pEo5pUNG3XnhsqrosWeJT37nYpfqJKw7QfQ7RFO9nlrRennEM9qeHnj95Q+rLTy/bKgld/gJCvLiAO5J8UUlnQuxiXEFBpDqtHmUhV1OYwixsKqP+AaPC8HPArKvUX+x4oPUVx7ufwZShMH3lsv04jstD82ptwE5g8RQflrrW8A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de; spf=pass smtp.mailfrom=lst.de; arc=none smtp.client-ip=213.95.11.211 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lst.de Received: by verein.lst.de (Postfix, from userid 2407) id 78C0A68C7B; Tue, 24 Feb 2026 15:01:18 +0100 (CET) Date: Tue, 24 Feb 2026 15:01:18 +0100 From: Christoph Hellwig To: "Darrick J. Wong" Cc: brauner@kernel.org, miklos@szeredi.hu, bpf@vger.kernel.org, hch@lst.de, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org Subject: Re: [PATCH 2/2] iomap: allow NULL swap info bdev when activating swapfile Message-ID: <20260224140118.GB9516@lst.de> References: <177188733433.3935463.11119081161286211234.stgit@frogsfrogsfrogs> <177188733484.3935463.443855246947996750.stgit@frogsfrogsfrogs> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <177188733484.3935463.443855246947996750.stgit@frogsfrogsfrogs> User-Agent: Mutt/1.5.17 (2007-11-01) On Mon, Feb 23, 2026 at 03:08:08PM -0800, Darrick J. Wong wrote: > From: Darrick J. Wong > > All current users of the iomap swapfile activation mechanism are block > device filesystems. This means that claim_swapfile will set > swap_info_struct::bdev to inode->i_sb->s_bdev of the swap file. > > However, a subsequent patch to fuse will add iomap infrastructure so > that fuse servers can be asked to provide file mappings specifically for > swap files. That sounds pretty sketchy. How do you make sure that is safe vs memory reclaim deadlocks? Does someone really need this feature?