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[97.116.180.154]) by smtp.gmail.com with ESMTPSA id 8926c6da1cb9f-4ea75440a2fsm76767173.45.2025.01.16.07.38.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 16 Jan 2025 07:38:07 -0800 (PST) Message-ID: Date: Thu, 16 Jan 2025 09:38:07 -0600 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: mount api: Q on behavior of mount_single vs. get_tree_single To: Christian Brauner Cc: linux-fsdevel@vger.kernel.org, David Howells , Alexander Viro References: <732c3de1-ef0b-49a9-b2c2-0c3c5e718a40@redhat.com> <20250116-erbeben-waren-2ad516da1343@brauner> Content-Language: en-US From: Eric Sandeen In-Reply-To: <20250116-erbeben-waren-2ad516da1343@brauner> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 1/16/25 4:28 AM, Christian Brauner wrote: > On Wed, Jan 15, 2025 at 10:50:31AM -0600, Eric Sandeen wrote: >> I was finally getting back to some more mount API conversions, >> and was looking at pstore, which I thought would be straightforward. >> >> I noticed that mount options weren't being accepted, and I'm fairly >> sure that this is because there's some internal or hidden mount of >> pstore, and mount is actually a remount due to it using a single >> superblock. (looks like it was some sort of clone mount done under > > Yes, some legacy filesystems behave that way unforunately. Is it not the case that every current (or past) user of mount_single behave[sd] this way due to the internals of mount_single()? gadgetfs, configfs, debugfs, tracefs, efivars, openpromfs and more all currently call get_tree_single (and used to call mount_single, which did the reconfigure for them). Or am I missing something? ... > I would think we should make this the filesystems problem or add a > get_tree_single_reconfigure() helper that the few filesystems that need > this behavior can use. Thoughts? I wasn't seeing this as individual filesystems needing it, it looked to me like every filesystem that used to call mount_single() automatically got the behavior. So was looking at this from a consistency/regression POV. While it seems odd to me that mounting any "_single" sb filesystem would reconfigure all of its current mounts on a new mount, that's the way it used to work for everyone, as far as I can tell, so I was assuming that we'd need to keep the behavior. But if it's a question of just fixing it up per-filesystem, I don't mind going that route either. Thanks, -Eric