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 D5B3122A813 for ; Mon, 22 Sep 2025 17:20:55 +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=1758561657; cv=none; b=qHG6uueSnDSipnO8XsmD6TxJI15KM1i9OAYAyInPj1uOTZgfEqRGiVZ8lNXso0tCZorY8pb/EU3amNBU/mEEhXCkmn6cPPnMf2396vAxGSbzSOu3G/zemPuVbyrOZj8So7soKaDrLpsBMwzjIc15GCrBt6Nm0Oa6TmGTOVuKFBs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758561657; c=relaxed/simple; bh=1liFhTO2+Ef51eluIvg5LOTXvTvmUZTypWiNv6m2vOU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=aK+8FzPL6nQX3ImVmskjjkHjJOs/DDUHH9TfmpkL1dLvSPB3Xc/La5HHwvcTNeblhozJVENL4O5ihODDjqeSxtQZK9mBZjJTKffDqjGCpygzlpsCM2F7rWFKrIMpk+2XYRL/L+2r65DwYTGLmNdZuLljCBtzaaks90gtHzJJNgA= 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=JSHWbUdS; 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="JSHWbUdS" 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=ZUqYeyVCAhhyrM17pHdpamEteiDug+p2Bn/wU9XYNrU=; b=JSHWbUdS/3Ky/exr64mSfHrKwL dkB8RmDt9ZDfqNR+z9VRooU0/xB+Dz63oTzmVmj3qs7GKRIvldeJGajBhhRl8psGhvHSXwPtRzIDq 85yuP1lm4+69YJqcD+zaGOBkDrBq5g8+57eDpJDMcMxWDio6cIkGnCebUq7x1eRk0OUGPKGhhKv6r Tmxt0hvABQkGCY+hmlh9CCKB4J9n3lUYw8heWBGg4Ukb9qVLKm7AafvGNeRnOBRXx/lLx0pi9lmN2 B2plyXmLfhwugDswFsM79HYgSfB+b6AqtxfyqB1fzG4VzbQpDMPOP/pLr0NSkQyekKKyRMIHpaEC+ 1rOLdK4A==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1v0kDf-0000000B6H6-2H4v; Mon, 22 Sep 2025 17:20:55 +0000 Date: Mon, 22 Sep 2025 10:20:55 -0700 From: Christoph Hellwig To: Demi Marie Obenour Cc: Christoph Hellwig , linux-btrfs@vger.kernel.org Subject: Re: Can the output of FIEMAP on BTRFS be used to check if a file and its reflink copy might have diverged? Message-ID: References: <38f350b0-9a71-4627-9d36-57bf2f85e67a@gmail.com> Precedence: bulk X-Mailing-List: linux-btrfs@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: <38f350b0-9a71-4627-9d36-57bf2f85e67a@gmail.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Mon, Sep 22, 2025 at 01:18:52PM -0400, Demi Marie Obenour wrote: > Is it safe on XFS if there is no RT device and both files have been > fsync'd and are not modified by userspace? I believe this is the case > here: reflinks are used to snapshot the files before they are looked at. No. Yo ucan still have defragementation or garbage collection going on underneath.