From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Whitehouse Date: Thu, 14 Nov 2019 10:45:34 +0000 Subject: [Cluster-devel] [PATCH 30/32] gfs2: Don't demote a glock until its revokes are written In-Reply-To: <20191113213030.237431-31-rpeterso@redhat.com> References: <20191113213030.237431-1-rpeterso@redhat.com> <20191113213030.237431-31-rpeterso@redhat.com> Message-ID: List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hi, On 13/11/2019 21:30, Bob Peterson wrote: > Before this patch, run_queue would demote glocks based on whether > there are any more holders. But if the glock has pending revokes that > haven't been written to the media, giving up the glock might end in > file system corruption if the revokes never get written due to > io errors, node crashes and fences, etc. In that case, another node > will replay the metadata blocks associated with the glock, but > because the revoke was never written, it could replay that block > even though the glock had since been granted to another node who > might have made changes. > > This patch changes the logic in run_queue so that it never demotes > a glock until its count of pending revokes reaches zero. > > Signed-off-by: Bob Peterson I'm not sure this makes sense... if we demote the glock then the revokes should be written out during that process. So if that is not happening it is a bug. I don't think we should need to change the logic for deciding what we are going to demote? Steve. > --- > fs/gfs2/glock.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c > index ab72797e3ba1..082f70eb96db 100644 > --- a/fs/gfs2/glock.c > +++ b/fs/gfs2/glock.c > @@ -712,6 +712,9 @@ __acquires(&gl->gl_lockref.lock) > goto out_unlock; > if (nonblock) > goto out_sched; > + smp_mb(); > + if (atomic_read(&gl->gl_revokes) != 0) > + goto out_sched; > set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags); > GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE); > gl->gl_target = gl->gl_demote_state;