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: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index ddc3e1e..3f45a14 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -103,16 +103,21 @@
__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);
else
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))
wake_up(&sdp->sd_glock_wait);
}
@@ -760,6 +765,7 @@
if (tmp) {
spin_unlock_bucket(hash);
kmem_cache_free(cachep, gl);
+ atomic_dec(&sdp->sd_glock_disposal);
gl = tmp;
} else {
hlist_bl_add_head_rcu(&gl->gl_list, &gl_hash_table[hash]);
diff --git a/fs/gfs2/glock.h b/fs/gfs2/glock.h
index afa8bfe..aea1606 100644
--- a/fs/gfs2/glock.h
+++ b/fs/gfs2/glock.h
@@ -230,7 +230,7 @@
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);
diff --git a/fs/gfs2/lock_dlm.c b/fs/gfs2/lock_dlm.c
index c80485c..98c80d8 100644
--- a/fs/gfs2/lock_dlm.c
+++ b/fs/gfs2/lock_dlm.c
@@ -30,7 +30,7 @@
switch (gl->gl_lksb.sb_status) {
case -DLM_EUNLOCK: /* Unlocked, so glock can be freed */
- call_rcu(&gl->gl_rcu, gfs2_glock_free);
+ gfs2_glock_free(gl);
return;
case -DLM_ECANCEL: /* Cancel while getting lock */
ret |= LM_OUT_CANCELED;
@@ -165,7 +165,7 @@
int error;
if (gl->gl_lksb.sb_lkid == 0) {
- call_rcu(&gl->gl_rcu, gfs2_glock_free);
+ gfs2_glock_free(gl);
return;
}
diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index a39c103..67654d0 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -928,14 +928,9 @@
{ 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,
};