From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Subject: Re: [PATCH 1/2] open: add close_range() Date: Tue, 21 May 2019 20:20:09 +0100 Message-ID: <20190521192009.GK17978@ZenIV.linux.org.uk> References: <20190521150006.GJ17978@ZenIV.linux.org.uk> <20190521113448.20654-1-christian@brauner.io> <28114.1558456227@warthog.procyon.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <28114.1558456227@warthog.procyon.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: David Howells Cc: Christian Brauner , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, jannh@google.com, fweimer@redhat.com, oleg@redhat.com, tglx@linutronix.de, torvalds@linux-foundation.org, arnd@arndb.de, shuah@kernel.org, tkjos@android.com, ldv@altlinux.org, miklos@szeredi.hu, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org, x86@kernel.org List-ID: On Tue, May 21, 2019 at 05:30:27PM +0100, David Howells wrote: > If we can live with close_from(int first) rather than close_range(), then this > can perhaps be done a lot more efficiently by: > > new = alloc_fdtable(first); > spin_lock(&files->file_lock); > old = files_fdtable(files); > copy_fds(new, old, 0, first - 1); > rcu_assign_pointer(files->fdt, new); > spin_unlock(&files->file_lock); > clear_fds(old, 0, first - 1); > close_fdt_from(old, first); > kfree_rcu(old); I really hate to think how that would interact with POSIX locks...