From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH 08/20] sysfs: Optimize just changing the sysfs file mode. Date: Thu, 21 May 2009 16:29:10 +0900 Message-ID: <4A1502C6.5020103@kernel.org> References: <1242865694-2100-1-git-send-email-ebiederm@xmission.com> <1242865694-2100-2-git-send-email-ebiederm@xmission.com> <1242865694-2100-3-git-send-email-ebiederm@xmission.com> <1242865694-2100-4-git-send-email-ebiederm@xmission.com> <1242865694-2100-5-git-send-email-ebiederm@xmission.com> <1242865694-2100-6-git-send-email-ebiederm@xmission.com> <1242865694-2100-7-git-send-email-ebiederm@xmission.com> <1242865694-2100-8-git-send-email-ebiederm@xmission.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Andrew Morton , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Cornelia Huck , linux-fsdevel@vger.kernel.org, "Eric W. Biederman" To: "Eric W. Biederman" Return-path: Received: from hera.kernel.org ([140.211.167.34]:38704 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751135AbZEUH3U (ORCPT ); Thu, 21 May 2009 03:29:20 -0400 In-Reply-To: <1242865694-2100-8-git-send-email-ebiederm@xmission.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Eric W. Biederman wrote: > From: Eric W. Biederman > > Don't allocate a struct iattr for the sysfs dentry if just > the mode changes because we have a field for that on the > sysfs_dirent, and we can trigger that case with sysfs_chmod_file. > > Signed-off-by: Eric W. Biederman > --- > fs/sysfs/inode.c | 22 ++++++++++++++-------- > 1 files changed, 14 insertions(+), 8 deletions(-) > > diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c > index 555f0ff..70ff2a2 100644 > --- a/fs/sysfs/inode.c > +++ b/fs/sysfs/inode.c > @@ -60,12 +60,16 @@ int sysfs_setattr(struct dentry * dentry, struct iattr * iattr) > return error; > > iattr->ia_valid &= ~ATTR_SIZE; /* ignore size changes */ > + if (iattr->ia_valid & ATTR_MODE) { > + if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) > + iattr->ia_mode &= ~S_ISGID; > + } > > error = inode_setattr(inode, iattr); > if (error) > return error; > > - if (!sd_iattr) { > + if (!sd_iattr && (ia_valid & ~ATTR_MODE)) { > /* setting attributes for the first time, allocate now */ > sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL); > if (!sd_iattr) > @@ -78,6 +82,13 @@ int sysfs_setattr(struct dentry * dentry, struct iattr * iattr) > sd->s_iattr = sd_iattr; > } > > + if (ia_valid & ATTR_MODE) > + sd->s_mode = iattr->ia_mode; > + > + /* If we don't need the extra attributes leave */ > + if (!sd_iattr) > + return 0; One visible difference is lack of timestamp update. Is there any use case where sysfs file mode changing needs to be fast? Thanks. -- tejun