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gfs2: Add missing rcu locking for glock lookup

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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 <anprice@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Andrew Price 2017-02-22 12:05:03 -05:00 committed by Greg Kroah-Hartman
parent c8cdd9234c
commit 4cf918c804
1 changed files with 5 additions and 0 deletions
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5
fs/gfs2/glock.c
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@ -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);
}