From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Whitehouse Subject: Re: [PATCH] gfs2: Get rid of I_MUTEX_QUOTA usage Date: Thu, 26 Apr 2012 14:28:39 +0100 Message-ID: <1335446919.2722.21.camel@menhir> References: <1335446430-10561-1-git-send-email-jack@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org, Al Viro , "J. Bruce Fields" To: Jan Kara Return-path: Received: from mx1.redhat.com ([209.132.183.28]:27220 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752601Ab2DZN3Y (ORCPT ); Thu, 26 Apr 2012 09:29:24 -0400 In-Reply-To: <1335446430-10561-1-git-send-email-jack@suse.cz> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Hi, On Thu, 2012-04-26 at 15:20 +0200, Jan Kara wrote: > GFS2 uses i_mutex on its system quota inode to synchronize writes to > quota file. Since this is an internal inode to GFS2 (not part of directory > hiearchy or visible by user) we are safe to define locking rules for it. So > let's just get it its own locking class to make it clear. > It is visible to the user if the gfs2 metadata filesystem is mounted. That used to be the way in which the quotas were set by gfs2_quota. However that is really considered obsolete now, so maybe we don't have to support that interface any more... the gfs2_quota package is no longer in distros as the generic quota package does the job for us these days. I'd just been looking at using sd_quota_mutex instead of the inode mutex, but run into that same issue, Steve. > CC: Steven Whitehouse > Signed-off-by: Jan Kara > --- > fs/gfs2/ops_fstype.c | 8 ++++++++ > fs/gfs2/quota.c | 2 +- > 2 files changed, 9 insertions(+), 1 deletions(-) > > So this is probably the simplest what can be done for GFS2 (actually OCFS2 > does the same for internal system files). Compile tested only. Steven? > > diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c > index 6f3a18f..ae8f225 100644 > --- a/fs/gfs2/ops_fstype.c > +++ b/fs/gfs2/ops_fstype.c > @@ -19,6 +19,7 @@ > #include > #include > #include > +#include > > #include "gfs2.h" > #include "incore.h" > @@ -767,6 +768,7 @@ fail: > return error; > } > > +static struct lock_class_key gfs2_quota_imutex_key; > > static int init_inodes(struct gfs2_sbd *sdp, int undo) > { > @@ -804,6 +806,12 @@ static int init_inodes(struct gfs2_sbd *sdp, int undo) > fs_err(sdp, "can't get quota file inode: %d\n", error); > goto fail_rindex; > } > + /* > + * i_mutex on quota files is special. Since this inode is hidden system > + * file, we are safe to define locking ourselves. > + */ > + lockdep_set_class(&sdp->sd_quota_inode->i_mutex, > + &gfs2_quota_imutex_key); > > error = gfs2_rindex_update(sdp); > if (error) > diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c > index 6019da3..970598b 100644 > --- a/fs/gfs2/quota.c > +++ b/fs/gfs2/quota.c > @@ -772,7 +772,7 @@ static int do_sync(unsigned int num_qd, struct gfs2_quota_data **qda) > return -ENOMEM; > > sort(qda, num_qd, sizeof(struct gfs2_quota_data *), sort_qd, NULL); > - mutex_lock_nested(&ip->i_inode.i_mutex, I_MUTEX_QUOTA); > + mutex_lock(&ip->i_inode.i_mutex); > for (qx = 0; qx < num_qd; qx++) { > error = gfs2_glock_nq_init(qda[qx]->qd_gl, LM_ST_EXCLUSIVE, > GL_NOCACHE, &ghs[qx]);