From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: [PATCH v2] fadvise: introduce POSIX_FADV_DONTNEED_FS Date: Wed, 27 Apr 2011 12:33:08 -0600 Message-ID: <20110427183308.GA16716@parisc-linux.org> References: <1303928027-5100-1-git-send-email-andrea@betterlinux.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1303928027-5100-1-git-send-email-andrea-oIIqvOZpAevzfdHfmsDf5w@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Andrea Righi Cc: Andrew Morton , Dave Chinner , Mike Frysinger , Al Viro , Arnd Bergmann , linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-api@vger.kernel.org On Wed, Apr 27, 2011 at 08:13:47PM +0200, Andrea Righi wrote: > @@ -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 (capable(CAP_SYS_ADMIN)) > + drop_pagecache_sb(file->f_dentry->d_sb, NULL); > + else > + ret = -EPERM; > + break; > default: > ret = -EINVAL; > } Mmm ... what if I open /dev/sdxyz and call fadvise() on it? I think you end up flushing /dev's page cache entries, instead of the filesystem which is on /dev/sdxyz. If I understand correctly, you want mapping->host->i_sb instead of file->f_dentry->d_sb. -- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step." From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757337Ab1D0SdM (ORCPT ); Wed, 27 Apr 2011 14:33:12 -0400 Received: from palinux.external.hp.com ([192.25.206.14]:46279 "EHLO mail.parisc-linux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753773Ab1D0SdK (ORCPT ); Wed, 27 Apr 2011 14:33:10 -0400 Date: Wed, 27 Apr 2011 12:33:08 -0600 From: Matthew Wilcox To: Andrea Righi Cc: Andrew Morton , Dave Chinner , Mike Frysinger , Al Viro , Arnd Bergmann , linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] fadvise: introduce POSIX_FADV_DONTNEED_FS Message-ID: <20110427183308.GA16716@parisc-linux.org> References: <1303928027-5100-1-git-send-email-andrea@betterlinux.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1303928027-5100-1-git-send-email-andrea@betterlinux.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 27, 2011 at 08:13:47PM +0200, Andrea Righi wrote: > @@ -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 (capable(CAP_SYS_ADMIN)) > + drop_pagecache_sb(file->f_dentry->d_sb, NULL); > + else > + ret = -EPERM; > + break; > default: > ret = -EINVAL; > } Mmm ... what if I open /dev/sdxyz and call fadvise() on it? I think you end up flushing /dev's page cache entries, instead of the filesystem which is on /dev/sdxyz. If I understand correctly, you want mapping->host->i_sb instead of file->f_dentry->d_sb. -- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step."