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[209.85.208.170]) by smtp.gmail.com with ESMTPSA id s2sm3037880ljj.36.2021.04.12.09.24.05 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 12 Apr 2021 09:24:06 -0700 (PDT) Received: by mail-lj1-f170.google.com with SMTP id a36so5231814ljq.8 for ; Mon, 12 Apr 2021 09:24:05 -0700 (PDT) X-Received: by 2002:a05:6512:31c7:: with SMTP id j7mr10731751lfe.41.1618244634563; Mon, 12 Apr 2021 09:23:54 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Linus Torvalds Date: Mon, 12 Apr 2021 09:23:38 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v6 24/40] fs: make helpers idmap mount aware To: Anton Altaparmakov Cc: "christian.brauner@ubuntu.com" , "James.Bottomley@hansenpartnership.com" , "adilger.kernel@dilger.ca" , "alban@kinvolk.io" , "arnd@arndb.de" , "casey@schaufler-ca.com" , "containers@lists.linux-foundation.org" , "corbet@lwn.net" , "cyphar@cyphar.com" , "dhowells@redhat.com" , "dmitry.kasatkin@gmail.com" , "ebiederm@xmission.com" , "geofft@ldpreload.com" , "hch@lst.de" , "hirofumi@mail.parknet.co.jp" , "john.johansen@canonical.com" , "josh@joshtriplett.org" , "keescook@chromium.org" , "lennart@poettering.net" , "linux-api@vger.kernel.org" , "linux-ext4@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-integrity@vger.kernel.org" , "linux-security-module@vger.kernel.org" , "linux-xfs@vger.kernel.org" , "luto@kernel.org" , "mpatel@redhat.com" , "paul@paul-moore.com" , "selinux@vger.kernel.org" , "seth.forshee@canonical.com" , "smbarber@chromium.org" , "stephen.smalley.work@gmail.com" , "tkjos@google.com" , "tycho@tycho.ws" , "tytso@mit.edu" , "viro@zeniv.linux.org.uk" , "zohar@linux.ibm.com" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Mon, Apr 12, 2021 at 5:05 AM Anton Altaparmakov wrote: > > Shouldn't that be using mnt_userns instead of &init_user_ns both for the setattr_prepare() and setattr_copy() calls? It doesn't matter for a filesystem that hasn't marked itself as supporting idmaps. If the filesystem doesn't set FS_ALLOW_IDMAP, then mnt_userns is always going to be &init_user_ns. That said, I don't think you are wrong - it would probably be a good idea to pass down the 'mnt_userns' argument just to avoid confusion. But if you look at the history, you'll see that adding the mount namespace argument to the helper functions (like setattr_copy()) happened before the actual "switch the filesystem setattr() function over to get the namespace argument". So the current situation is partly an artifact of how the incremental filesystem changes were done. Linus