From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrea Righi Subject: Re: [PATCH] fadvise: introduce POSIX_FADV_DONTNEED_FS Date: Wed, 27 Apr 2011 17:12:19 +0200 Message-ID: <20110427151218.GA15335@linux.betterlinux.com> References: <1303914545-15642-1-git-send-email-andrea@betterlinux.com> <201104271700.13013.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andrew Morton , Dave Chinner , Mike Frysinger , Al Viro , linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org To: Arnd Bergmann Return-path: Received: from mail-ww0-f42.google.com ([74.125.82.42]:58866 "EHLO mail-ww0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752606Ab1D0PMZ (ORCPT ); Wed, 27 Apr 2011 11:12:25 -0400 Content-Disposition: inline In-Reply-To: <201104271700.13013.arnd@arndb.de> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Wed, Apr 27, 2011 at 05:00:12PM +0200, Arnd Bergmann wrote: > On Wednesday 27 April 2011 16:29:05 Andrea Righi wrote: > > diff --git a/include/linux/fadvise.h b/include/linux/fadvise.h > > index e8e7471..dc9ce98 100644 > > --- a/include/linux/fadvise.h > > +++ b/include/linux/fadvise.h > > @@ -13,9 +13,11 @@ > > #if defined(__s390x__) > > #define POSIX_FADV_DONTNEED 6 /* Don't need these pages. */ > > #define POSIX_FADV_NOREUSE 7 /* Data will be accessed once. */ > > +#define POSIX_FADV_DONTNEED_FS 8 /* Don't need these filesystem pages. */ > > #else > > #define POSIX_FADV_DONTNEED 4 /* Don't need these pages. */ > > #define POSIX_FADV_NOREUSE 5 /* Data will be accessed once. */ > > +#define POSIX_FADV_DONTNEED_FS 6 /* Don't need these filesystem pages. */ > > #endif > > > > #endif /* FADVISE_H_INCLUDED */ > > Please don't make the s390 mess worse than it already is here. > I think the best solution would be to assign new values starting > from 8 so they can be common for all architectures. Agreed. > > > @@ -127,6 +128,12 @@ SYSCALL_DEFINE(fadvise64_64)(int fd, loff_t offset, loff_t len, int advice) > > invalidate_mapping_pages(mapping, start_index, > > end_index); > > break; > > + case POSIX_FADV_DONTNEED_FS: > > + if (!current_euid()) > > + drop_pagecache_sb(file->f_dentry->d_sb, NULL); > > + else > > + ret = -EPERM; > > + break; > > I somewhat disagree with keying the capability off the UID value, even > if that is what the sysctl uses. CAP_SYS_ADMIN is not that nice either, but > I think it's better than the UID here. OK, I also prefer CAP_SYS_ADMIN. > > Aside from these, I like the patch. > > Arnd I'll wait for other comments and post another version with the changes you suggested. Thanks for looking at it. -Andrea