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[209.85.167.52]) by smtp.gmail.com with ESMTPSA id z89-v6sm949211ljb.71.2018.10.26.13.42.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 26 Oct 2018 13:42:18 -0700 (PDT) Received: by mail-lf1-f52.google.com with SMTP id m18-v6so1875217lfl.11 for ; Fri, 26 Oct 2018 13:42:18 -0700 (PDT) X-Received: by 2002:a19:288c:: with SMTP id o134-v6mr3304130lfo.124.1540586537634; Fri, 26 Oct 2018 13:42:17 -0700 (PDT) MIME-Version: 1.0 References: <10b12992-3570-4646-374b-82cbd7276839@acm.org> <1538503063.193396.6.camel@acm.org> <1538521591.193396.8.camel@acm.org> <20181025213144.GB24709@flashbox> <20181025225548.GA10326@flashbox> <1540576908.66186.103.camel@acm.org> <20181026180515.GA12129@flashbox> In-Reply-To: From: Linus Torvalds Date: Fri, 26 Oct 2018 13:42:01 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] libosd: Remove ignored __weak attribute To: Nick Desaulniers Cc: bvanassche@acm.org, ooo@electrozaur.com, jejb@linux.vnet.ibm.com, martin.petersen@oracle.com, linux-scsi@vger.kernel.org, Linux Kernel Mailing List , Nathan Chancellor , Christoph Hellwig , Kees Cook Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 26, 2018 at 1:06 PM Nick Desaulniers wrote: > > Is removing a filesystem considered a userspace breakage? Yes - if a user notices. The key word is *USER*. Note that it's not "user space". It's not about _programs_ noticing, it's literally about users and their workflows. If some change breaks a real user workflow, it needs to be reverted. So this is not about ABI or anything like that. We've had cases where the ABI stayed the same, but the order of device probing changed, and that broke peoples setups (because now /dev/sdb and /dev/sda switched places), and we had to revert. It's literally about "if a user upgrades a kernel, and something no longer works, it's a regression". In general, a good idea is "if you have to wonder about it, just don't do it". Because it turns out that users are odd, and often do odd things much after you'd have thought they'd have long since switched to more modern hardware or filesystems. Linus