From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 9E5FF3B71A0 for ; Wed, 8 Jul 2026 14:32:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783521155; cv=none; b=bt5b1krPMX1khcyCb8xll/kMy/oM4LFpyrFhVRvuJsW4iN5wulnRKfxMpxjjVoVom024xpf5SIetJ5z7khi5nPdIy3m2cqGDoxPRxm79B44xHTy/b4LZfXPxQMoRM8gvR/fusV3PRKSiQJ7nxi3SlcW64CtQu1RFMi0n86LZP7s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783521155; c=relaxed/simple; bh=LOeEllHoi+TWL4E3SItVJM1jMccA7PR2St6wIBOhIZ8=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=fLvE+m+DATZDCYh26mTpwfFMUpWWknNciKOQWsgFqi9VewDM4AHwCwHvcgZ8v/fHKXqvnWjr0YtfM936LhBpx9lDeK88EMLNRodO7eA+vrTP6HfdgwZsmIUQugZ57zWDooMIAQj6ErTNUZOHOm1IqgRCgUZHUiSmj1emOPDTdCo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=IQaCwDvN; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="IQaCwDvN" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1783521152; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=+JLlRmFoV/9EpXUUB3MyVbYbqU3NmpLcJQ510IuP4ZY=; b=IQaCwDvN1CWMqS67Se9SKTAhhqCa4NQS4ZuUdWvRpGWzgR4BWH1hEwCY2eZ9bnEprV7db1 MhcPX2PeQe9XJDYI9NZroYVX56MVkjtIzShtrOtXv6IvU4xJWQLEGINlbdzxAEd1UiqaK8 A5G74aMEtr1zEluKDuCnJPJvMB9Q6Ag= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-311-EmUh0cirPC-88CyMqHzsXA-1; Wed, 08 Jul 2026 10:32:28 -0400 X-MC-Unique: EmUh0cirPC-88CyMqHzsXA-1 X-Mimecast-MFC-AGG-ID: EmUh0cirPC-88CyMqHzsXA_1783521147 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7498D18EC1DA; Wed, 8 Jul 2026 14:31:57 +0000 (UTC) Received: from localhost (unknown [10.44.33.4]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 3443E1955D86; Wed, 8 Jul 2026 14:31:55 +0000 (UTC) From: Giuseppe Scrivano To: Miklos Szeredi Cc: linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, Amir Goldstein Subject: Re: [PATCH] ovl: add ioctls to retrieve layer file descriptors In-Reply-To: (Miklos Szeredi's message of "Wed, 8 Jul 2026 16:08:56 +0200") References: <20260708095831.3381978-1-gscrivan@redhat.com> <878q7l8y4y.fsf@redhat.com> Date: Wed, 08 Jul 2026 16:31:54 +0200 Message-ID: <87wlv57dt1.fsf@redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Miklos Szeredi writes: > On Wed, 8 Jul 2026 at 14:27, Giuseppe Scrivano wrote: > >> is there any existing user of such a mechanism? I don't see any mount >> specific info under /proc or /sys. > > Not yet, but I think it would be good to have one. It's definitely a > bigger bite than adding an ioctl(), though. > >> >> OVL_IOC_GET_LAYERS_INFO: copy a struct ovl_layers_info to userspace >> >> with numlower, numlowerdata, and has_upper. >> > >> > Isn't this info obtainable via statmount(2) already? If not, it >> > should be there, instead of a specialized ioctl. >> > >> no that is not exposed by statmount > > I mean, you should be able to get that info by counting the lowerdir+, > datadir+ and upperdir options, no? Amir suggested to add that functionality when I've asked for some feedback before sending the patch here. I am fine to drop it if this is the consensus although I see its utility from user space. Regards, Giuseppe