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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: <stable@vger.kernel.org> # 4.3+
Signed-off-by: Andrew Price <anprice@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
This commit is contained in:
Andrew Price 2017-02-22 12:05:03 -05:00 committed by Bob Peterson
parent c548a1c175
commit f38e5fb95a
1 changed files with 5 additions and 0 deletions
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5
fs/gfs2/glock.c
View File

@ -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);
}