From f38e5fb95a1f8feda88531eedc98f69b24748712 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 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. Cc: # 4.3+ Signed-off-by: Andrew Price Signed-off-by: Andreas Gruenbacher Signed-off-by: Bob Peterson --- fs/gfs2/glock.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 2928f1209b67..d004debe2856 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); } -- 2.20.1