From: Arnd Bergmann Subject: Re: [PATCH 1/6] statx: Add a system call to make enhanced file info available Date: Fri, 13 May 2016 17:28:11 +0200 Message-ID: <3204439.9qcmCY96fi@wuerfel> References: <20160510070421.GB30896@infradead.org> <6897.1462868755@warthog.procyon.org.uk> <20160512091141.GA22420@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: David Howells , linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-afs-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, samba-technical-w/Ol4Ecudpl8XjKLYN78aQ@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Christoph Hellwig Return-path: In-Reply-To: <20160512091141.GA22420-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org> Sender: linux-nfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-ext4.vger.kernel.org On Thursday 12 May 2016 02:11:41 Christoph Hellwig wrote: > On Tue, May 10, 2016 at 09:25:55AM +0100, David Howells wrote: > > Because it's not necessarily a perfectly working version of it. See the Y2037 > > problem for example. > > > > I was assuming that C libraries might want to update the struct stat and the > > stat call() to provide fields that aren't currently there in Linux but are in > > other OS's. We could even dispense with older stat syscalls on new arches. > > Please stop this whole let's get rid of old syscalls on new > architectures stuff. This just means we have to do the translation > multiple, and the one in userspace is more costly as we it needs to be > in every copy of the library. And times where we had a single libc > instance (nevermind implementation) are long over if we ever actually > had them. I'm trying to understand what that means for the 64-bit time_t syscalls. The patch series I did last year had a replacement 'sys_newfstatat()' syscall but IIRC no other stat variant, the idea being that we would only need to provide this one to the libc and have user space emulate the stat/fstat/lstat/fstatat variants based on that. With the statx introduction, I was hoping to no longer have to add that syscall but instead have libc do everything on top of sys_statx(). Do you think that is reasonable, given that we won't be allowed to call any of the existing stat() variants for a y2038-safe libc build[1], or should we plan to keep needing replacement fstatat (and possibly stat/lstat/fstat) syscalls with 64-bit time_t even after statx() support is merged into the kernel. Arnd [1] the glibc developers plan to allow compatibility for 32-bit time_t and 64-bit time_t in the same binary, but any user space code built with 64-bit time_t must never call into kernel interfaces that use a 32-bit time_t. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html