Commit fc0e38da authored by Steven Whitehouse's avatar Steven Whitehouse

GFS2: Fix glock deallocation race

This patch fixes a race in deallocating glocks which was introduced
in the RCU glock patch. We need to ensure that the glock count is
kept correct even in the case that there is a race to add a new
glock into the hash table. Also, to avoid having to wait for an
RCU grace period, the glock counter can be decremented before
call_rcu() is called.
Signed-off-by: default avatarSteven Whitehouse <>
parent 662e3a55
......@@ -103,16 +103,21 @@ static inline void spin_unlock_bucket(unsigned int hash)
__bit_spin_unlock(0, (unsigned long *)bl);
void gfs2_glock_free(struct rcu_head *rcu)
static void gfs2_glock_dealloc(struct rcu_head *rcu)
struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu);
struct gfs2_sbd *sdp = gl->gl_sbd;
if (gl->gl_ops->go_flags & GLOF_ASPACE)
kmem_cache_free(gfs2_glock_aspace_cachep, gl);
kmem_cache_free(gfs2_glock_cachep, gl);
void gfs2_glock_free(struct gfs2_glock *gl)
struct gfs2_sbd *sdp = gl->gl_sbd;
call_rcu(&gl->gl_rcu, gfs2_glock_dealloc);
if (atomic_dec_and_test(&sdp->sd_glock_disposal))
......@@ -760,6 +765,7 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
if (tmp) {
kmem_cache_free(cachep, gl);
gl = tmp;
} else {
hlist_bl_add_head_rcu(&gl->gl_list, &gl_hash_table[hash]);
......@@ -230,7 +230,7 @@ extern void gfs2_gl_hash_clear(struct gfs2_sbd *sdp);
extern void gfs2_glock_finish_truncate(struct gfs2_inode *ip);
extern void gfs2_glock_thaw(struct gfs2_sbd *sdp);
extern void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl);
extern void gfs2_glock_free(struct rcu_head *rcu);
extern void gfs2_glock_free(struct gfs2_glock *gl);
extern int __init gfs2_glock_init(void);
extern void gfs2_glock_exit(void);
......@@ -30,7 +30,7 @@ static void gdlm_ast(void *arg)
switch (gl->gl_lksb.sb_status) {
case -DLM_EUNLOCK: /* Unlocked, so glock can be freed */
call_rcu(&gl->gl_rcu, gfs2_glock_free);
case -DLM_ECANCEL: /* Cancel while getting lock */
......@@ -165,7 +165,7 @@ static void gdlm_put_lock(struct gfs2_glock *gl)
int error;
if (gl->gl_lksb.sb_lkid == 0) {
call_rcu(&gl->gl_rcu, gfs2_glock_free);
......@@ -928,14 +928,9 @@ static const match_table_t nolock_tokens = {
{ Opt_err, NULL },
static void nolock_put_lock(struct gfs2_glock *gl)
call_rcu(&gl->gl_rcu, gfs2_glock_free);
static const struct lm_lockops nolock_ops = {
.lm_proto_name = "lock_nolock",
.lm_put_lock = nolock_put_lock,
.lm_put_lock = gfs2_glock_free,
.lm_tokens = &nolock_tokens,
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