From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (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 E94E8450C1 for ; Mon, 18 Sep 2023 20:33:53 +0000 (UTC) Received: from [127.0.0.1] ([98.35.210.218]) (authenticated bits=0) by mail.zytor.com (8.17.1/8.17.1) with ESMTPSA id 38IKXQ0J1708850 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Mon, 18 Sep 2023 13:33:27 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 38IKXQ0J1708850 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2023091101; t=1695069211; bh=Xq1BpfVZL3W4xv3SzKlLmP2NbrilOBD8XdeK58PoqgY=; h=Date:From:To:CC:Subject:In-Reply-To:References:From; b=nfeenvONH+MXsV3D1F076tXfcae5uJqqkegnmOu8gwgeUYfpxsLrOXNpxNdl92MU7 iPo2A4/hpmZvhA6Xtjuc81pBSh1MSml7N92Z56tYbH7cWyxVMa3ogyr6UOSjQeatyL xt9sgYJ9xF/n/oDL+1VozAVdGwi7ZJeIA6IAnGWNSihPDu3pgMys16uhZUZEI6h7Nm xchzwnoDWQAR5a4EyxS89462kUG/B6OM6JCtNRZxCWwLMFZ+xnqEQ4WtXyeI2Er/is H6ulotojz3I5OwQ6vi+atn8u6Rz/pF1jJyJAzC5L1do8d1J6UK6+st+q1s4aCim0Hz GJxv1N1LcPbHw== Date: Mon, 18 Sep 2023 13:33:23 -0700 From: "H. Peter Anvin" To: Jiri Kosina , Linus Torvalds CC: Jan Kara , "Theodore Ts'o" , NeilBrown , James Bottomley , Dave Chinner , Eric Sandeen , Steven Rostedt , Guenter Roeck , Christoph Hellwig , ksummit@lists.linux.dev, linux-fsdevel@vger.kernel.org Subject: Re: [MAINTAINERS/KERNEL SUMMIT] Trust and maintenance of file systems User-Agent: K-9 Mail for Android In-Reply-To: References: <20230907071801.1d37a3c5@gandalf.local.home> <169491481677.8274.17867378561711132366@noble.neil.brown.name> <20230917185742.GA19642@mit.edu> <20230918111402.7mx3wiecqt5axvs5@quack3> Message-ID: <9569DF2A-343D-4E87-B78A-104C39DC6D68@zytor.com> Precedence: bulk X-Mailing-List: ksummit@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On September 18, 2023 12:32:05 PM PDT, Jiri Kosina wro= te: >On Mon, 18 Sep 2023, Linus Torvalds wrote: > >> But mmap() is *not* important for a filesystem that is used just for=20 >> data transport=2E I bet that FAT is still widely used, for example, and= =20 >> while exFAT is probably making inroads, I suspect most of us have used = a=20 >> USB stick with a FAT filesystem on it in the not too distant past=2E Ye= t I=20 >> doubt we'd have ever even noticed if 'mmap' didn't work on FAT=2E Becau= se=20 >> all you really want for data transport is basic read/write support=2E > >I am afraid this is not reflecting reality=2E > >I am pretty sure that "give me that document on a USB stick, and I'll tak= e=20 >a look" leads to using things like libreoffice (or any other editor liked= =20 >by general public) to open the file directly on the FAT USB stick=2E And= =20 >that's pretty much guaranteed to use mmap()=2E > I mean=2E=2E=2E fopen() on Linux optionally uses mmap()=2E=2E=2E and it us= ed to do so unconditionally, even=2E mmap() is a good match for stdio (at l= east the input side), so it is a reasonable thing to do=2E