From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 769B11EB36; Wed, 14 May 2025 04:57:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747198673; cv=none; b=OOKhqkoOd8/hVsUByPaT+5JmzGjhh13wxAVf8JEGBXq2k5dFGPNkavPvgyA7MB1fJg1uRGB8ZQEn26P4++e60vFE2RC7CK6XsuRq2M3jCgj8fb89rVPPjQz2BNtYi0BPIWMgQOiWSfAPxA5EL4oKrIY0mU82U+w5+ApmbBWrd58= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747198673; c=relaxed/simple; bh=dwk99c4ze/v5i5wZOUZMiW/juvBRI1Dowh87fegHPPU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Eyl5QRDdAPe7byoKc3IktzIvd2fMpjhCqJYo/Zt1JaI7jgpCqEo6QL9CWouDJEi/t3R5skBrIsh4vdxTIiw2Sx7HR82g0vbdvz/vy8jqlBae77JrFxSwgSP+Zcj6EfaaI+UOGKeL+XRwcfTYN0G6X+Hx/Ahj2Xmio+KV89VRo0Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=mlWc47Ks; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="mlWc47Ks" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=lOR/QFdLKjSv2hRskxp+GEMjKu5nrg0KkEjjkdDExL8=; b=mlWc47KsXRwAHvCgjdqBUmQKvS sM5pSRiAmJC3KJxrKUz57vLhhO0efr9bLIay48sdM2W2yPxeUyi/x9rb3RxWm8EQCcpazv+HfIh+h idYadG6vDCPr9oUbdjmJSvRw1Xj5pnEtpHc3tWOyTTBIiPR31j16wSe/loBYLYqyCu1HfoDL3V5c/ PyCNW3S10YotXJziTsp/1PqsbiM/Xsxr4tEOD/9wcfeWdi4apflyJ3RPztCCgiQdLCK3uowEG+kAm QHRtJ6QCklSO28jcyN55LDkV85RYsnWTSVVApTthNnx9kXxxBzPZkrMPPBR3QH7rlgO8VKa9F7spp gslrNHfg==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uF4Bj-0000000E2Ar-3yQb; Wed, 14 May 2025 04:57:51 +0000 Date: Tue, 13 May 2025 21:57:51 -0700 From: Christoph Hellwig To: Kevin Wolf Cc: Christoph Hellwig , Martin Wilck , dm-devel@lists.linux.dev, hreitz@redhat.com, mpatocka@redhat.com, snitzer@kernel.org, bmarzins@redhat.com, linux-kernel@vger.kernel.org, pbonzini@redhat.com Subject: Re: [PATCH 0/2] dm mpath: Interface for explicit probing of active paths Message-ID: References: <20250429165018.112999-1-kwolf@redhat.com> <47dd225b433b0df585a25084a2e793344eeda239.camel@suse.com> Precedence: bulk X-Mailing-List: linux-kernel@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: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Tue, May 13, 2025 at 11:29:09AM +0200, Kevin Wolf wrote: > Am 13.05.2025 um 07:55 hat Christoph Hellwig geschrieben: > > On Mon, May 12, 2025 at 05:18:43PM +0200, Kevin Wolf wrote: > > > Yes, it's a bit unfortunate, but we have to work with what we have. QEMU > > > doesn't even necessarily know that it's dealing with a multipath device, > > > so it just has to blindly try the ioctl and see if it works. > > > > Why is qemu even using SG_IO to start with? > > How else would you do SCSI passthrough? > > Ok, from your replies to Hannes I understand an implicit message, you > wouldn't. But I don't think that's really an answer, at least not for > all users. SG_IO is fine and the only way for SCSI passthrough. But doing SCSI passthrough through md-multipath just doesn't work. SCSI isn't built for layering, and ALUA and it's vendor-specific variants and alternatives certainly isn't. If you try that you're playing with fire and is not chance of ever moving properly.