From 4cf918c804c657c3a8b9cd4bb46171315bdfad62 Mon Sep 17 00:00:00 2001 From: Andrew Price Date: Wed, 22 Feb 2017 12:05:03 -0500 Subject: [PATCH] gfs2: Add missing rcu locking for glock lookup commit f38e5fb95a1f8feda88531eedc98f69b24748712 upstream. We must hold the rcu read lock across looking up glocks and trying to bump their refcount to prevent the glocks from being freed in between. Signed-off-by: Andrew Price Signed-off-by: Andreas Gruenbacher Signed-off-by: Bob Peterson Signed-off-by: Greg Kroah-Hartman --- fs/gfs2/glock.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 14cbf60167a7..133f322573b5 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -658,9 +658,11 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number, struct kmem_cache *cachep; int ret, tries = 0; + rcu_read_lock(); gl = rhashtable_lookup_fast(&gl_hash_table, &name, ht_parms); if (gl && !lockref_get_not_dead(&gl->gl_lockref)) gl = NULL; + rcu_read_unlock(); *glp = gl; if (gl) @@ -728,15 +730,18 @@ again: if (ret == -EEXIST) { ret = 0; + rcu_read_lock(); tmp = rhashtable_lookup_fast(&gl_hash_table, &name, ht_parms); if (tmp == NULL || !lockref_get_not_dead(&tmp->gl_lockref)) { if (++tries < 100) { + rcu_read_unlock(); cond_resched(); goto again; } tmp = NULL; ret = -ENOMEM; } + rcu_read_unlock(); } else { WARN_ON_ONCE(ret); } -- 2.17.1