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 6A842143C60 for ; Mon, 29 Jul 2024 10:40:47 +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=1722249649; cv=none; b=USiFBJ98oCDzTmltuQHXIuMR3fjGrcZ8mEUmYCRREtMJdHGKdIoC0vNdfdMmkAafzehc3I8x//YSE39aD6cXBncI6Abt/FgcYGJvW3nLj9Cuz7UWsrBHSqcRrszxkRdeRlgJ/pKZt9VN38e2j6+U4vFNyy+aQeX1sPrlvgKRam4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722249649; c=relaxed/simple; bh=6bfTWEmY7adZFRzBLuYfHsgyhzfx/9hvBN57Q13Jyn8=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=MO0e8WtBGvKlsXJX6W1Y5BP2ksaqw4CrvnAybSG3ICozC9XbgXlG3xTtcI7OIE8nKW9lNUuTBWNSqc++By4UBSpO36ddCZzNjkbYr89LcOFLH1guuoXmQgybrQSwe7aLqTzzkzS6hTir9avz4rqdEZ0QH0UXYlZ+5AetRYYd8iw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none 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=FkMRZLTQ; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none 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="FkMRZLTQ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1722249646; 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=dm2wu96gLk/Degb19SGPk73QQMk/RdMvun2wsoe8bRE=; b=FkMRZLTQ5a5nAvP8HA/mNKpcXr3jUuyJJUeWxUzkun4I0vIrlczcQoq5Qt/4vxZ1SFPFWA BtZ+hMjmw6JgVMlgaKA9qmnNkMebvvILGE/lygd0VZpGDPSD7q5AUPfCHX2/E1hfe1Bim6 Xa/NCDJeZWEyyll+dHzGmkUCgHhp0BY= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-541-grURU8TnPH-VlooMwkPHSg-1; Mon, 29 Jul 2024 06:40:41 -0400 X-MC-Unique: grURU8TnPH-VlooMwkPHSg-1 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (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-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D6D431955D42; Mon, 29 Jul 2024 10:40:40 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.45.224.31]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9011F1955D42; Mon, 29 Jul 2024 10:40:38 +0000 (UTC) From: Florian Weimer To: Mateusz Guzik Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Dave Chinner Subject: Re: Testing if two open descriptors refer to the same inode In-Reply-To: (Mateusz Guzik's message of "Mon, 29 Jul 2024 12:18:15 +0200") References: <874j88sn4d.fsf@oldenburg.str.redhat.com> Date: Mon, 29 Jul 2024 12:40:35 +0200 Message-ID: <875xsoqy58.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-api@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 * Mateusz Guzik: > On Mon, Jul 29, 2024 at 08:55:46AM +0200, Florian Weimer wrote: >> It was pointed out to me that inode numbers on Linux are no longer >> expected to be unique per file system, even for local file systems. > > I don't know if I'm parsing this correctly. > > Are you claiming on-disk inode numbers are not guaranteed unique per > filesystem? It sounds like utter breakage, with capital 'f'. Yes, POSIX semantics and traditional Linux semantics for POSIX-like local file systems are different. > While the above is not what's needed here, I guess it sets a precedent > for F_DUPINODE_QUERY (or whatever other name) to be added to handily > compare inode pointers. It may be worthwhile regardless of the above. > (or maybe kcmp could be extended?) I looked at kcmp as well, but I think it's dependent on checkpoint/restore. File sameness checks are much more basic than that. Thanks, Florian