From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [96.44.175.130]) (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 B948C25629 for ; Sat, 27 Jan 2024 14:59:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=96.44.175.130 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706367556; cv=none; b=buEzMgvaoTFwYYhui9BlO9R8H85QbXlvvT3tlvCeDDHY9LyVV3kJSxO2tbQuHSGs8jXIxNqscw4FxmAGf5TpE6dXlaPYjEoCEeqX6gLX8zFDnu3jdtYVNP6EAYk1sdl3L/I5GM0hYpn8KoeuWOL1GIaEDYpyoFttcr3Em1l+aj8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706367556; c=relaxed/simple; bh=jk7bFkoYzF+XHYrzjj0iuyo/A5nRVpoWxmzEke5I2tU=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=RD727JgqfU1aejh9yU0kk9MjkSscyf5RoCqYr9cqerohK7+nB+o5bVSUBoxtSeaPSufEqvbdMcogskFeT9ZT91C+lKOLNZ4StYiyZmFdML0s3/XUGhXOmWRUUq6x7WnnbZCeH3E/R/vgwUNl2dr4bq0ads6mifFzs5qUXGQ+UL8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=HansenPartnership.com; spf=pass smtp.mailfrom=HansenPartnership.com; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b=eGPk/ly2; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b=eGPk/ly2; arc=none smtp.client-ip=96.44.175.130 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=HansenPartnership.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=HansenPartnership.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="eGPk/ly2"; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="eGPk/ly2" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1706367553; bh=jk7bFkoYzF+XHYrzjj0iuyo/A5nRVpoWxmzEke5I2tU=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References:From; b=eGPk/ly2W+0rxG8znMh2lGom/4lK474TgBh0vHrn2eYKfvtGQajuVJAiomsuUUssG Sw20WzUKi92m7QyyjKjVGgfD5irZFWBIEUFFJ53pjT9Kfrl//u2aCjL2TR/LZeKias DFkWUzuMcAQO2FdPi/JUuKpPh2mKFxKJ9kjRM/18= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 8ABB91281BDA; Sat, 27 Jan 2024 09:59:13 -0500 (EST) Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavis, port 10024) with ESMTP id kmTTlxDjm9JL; Sat, 27 Jan 2024 09:59:13 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1706367553; bh=jk7bFkoYzF+XHYrzjj0iuyo/A5nRVpoWxmzEke5I2tU=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References:From; b=eGPk/ly2W+0rxG8znMh2lGom/4lK474TgBh0vHrn2eYKfvtGQajuVJAiomsuUUssG Sw20WzUKi92m7QyyjKjVGgfD5irZFWBIEUFFJ53pjT9Kfrl//u2aCjL2TR/LZeKias DFkWUzuMcAQO2FdPi/JUuKpPh2mKFxKJ9kjRM/18= Received: from lingrow.int.hansenpartnership.com (unknown [IPv6:2601:5c4:4302:c21::c14]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature RSA-PSS (2048 bits) server-digest SHA256) (Client did not present a certificate) by bedivere.hansenpartnership.com (Postfix) with ESMTPSA id 8C2C81281947; Sat, 27 Jan 2024 09:59:12 -0500 (EST) Message-ID: Subject: Re: [LSF/MM TOPIC] Making pseudo file systems inodes/dentries more like normal file systems From: James Bottomley To: Amir Goldstein , Steven Rostedt Cc: Greg Kroah-Hartman , lsf-pc@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Christian Brauner , Al Viro , Linus Torvalds Date: Sat, 27 Jan 2024 09:59:10 -0500 In-Reply-To: References: <20240125104822.04a5ad44@gandalf.local.home> <2024012522-shorten-deviator-9f45@gregkh> <20240125205055.2752ac1c@rorschach.local.home> <2024012528-caviar-gumming-a14b@gregkh> <20240125214007.67d45fcf@rorschach.local.home> <2024012634-rotten-conjoined-0a98@gregkh> <20240126101553.7c22b054@gandalf.local.home> <2024012600-dose-happiest-f57d@gregkh> <20240126114451.17be7e15@gandalf.local.home> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.42.4 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7bit On Sat, 2024-01-27 at 12:15 +0200, Amir Goldstein wrote: > I would like to attend the talk about what happened since we > suggested that you use kernfs in LSFMM 2022 and what has happened > since. I am being serious, I am not being sarcastic and I am not > claiming that you did anything wrong :) Actually, could we do the reverse and use this session to investigate what's wrong with the VFS for new coders? I had a somewhat similar experience when I did shiftfs way back in 2017. There's a huge amount of VFS knowledge you simply can't pick up reading the VFS API. The way I did it was to look at existing filesystems (for me overlayfs was the closes to my use case) as well (and of course configfs which proved to be too narrow for the use case). I'd say it took a good six months before I understood the subtleties enough to propose a new filesystem and be capable of answering technical questions about it. And remember, like Steve, I'm a fairly competent kernel programmer. Six months plus of code reading is an enormous barrier to place in front of anyone wanting to do a simple filesystem, and it would be way bigger if that person were new(ish) to Linux. It was also only after eventfs had gone around the houses several times that people suggested kernfs; it wasn't the default answer (why not?). Plus, if kernfs should have been the default answer early on, why is there no documentation at all? I mean fine, eventfs isn't really a new filesystem, it's an extension of the existing tracefs, which is perhaps how it sailed under the radar until the initial blow up, but that still doesn't answer how hostile an environment the VFS currently is to new coders who don't have six months or more to invest. James