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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <152720672288.9073.9868393448836301272.stgit@warthog.procyon.org.uk> <152720686035.9073.17015443936296474540.stgit@warthog.procyon.org.uk> To: Arnd Bergmann Cc: dhowells@redhat.com, Al Viro , Linux FS-devel Mailing List , linux-afs@lists.infradead.org, Linux Kernel Mailing List Subject: Re: [PATCH 21/32] VFS: Implement fsmount() to effect a pre-configured mount [ver #8] MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <26747.1528125864.1@warthog.procyon.org.uk> Date: Mon, 04 Jun 2018 16:24:24 +0100 Message-ID: <26748.1528125864@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Mon, 04 Jun 2018 15:24:25 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Mon, 04 Jun 2018 15:24:25 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'dhowells@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Arnd Bergmann wrote: > The prototype in the header doesn't match the one in the implementation, > which should cause a compile-time error, at least if syscalls.h is included > in namespace.c I've fixed that sort of thing up from kbuild warnings. > Do you have a particular use case in mind for the spare_4/spare_5 arguments? > If not, we can probably skip them. If we end up needing them after all, we > can always add a new syscall entry point, or use one of the flag bits to > decide whether the additional arguments are valid or not. Whilst that is true, these aren't really (or probably shouldn't be) hot path syscalls, so I would contend that just clearing the extra arguments shouldn't be much of a performance loss. On the other hand, syscall numbers are to some extent precious. If we hit ~512 syscalls we start to have an issue as we start to get overlaps. And, yes, I do have ideas for them involving ID mapping on mounts (ie. killing off shiftfs). > > COND_SYSCALL(sys_fsopen); > > +COND_SYSCALL(sys_fsmount); > > This should only be needed if the syscall is optional, which it doesn't > seem to be (same for the other ones here). Al removed them. David