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GFS2: Use RCU/hlist_bl based hash for quotas

PATCH New Abhijith Das 1 participant 1 message Jan 14, 2014 1 message not in the archive GFS2 file system

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Abhijith Das

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PATCH 1/4 GFS2: Use RCU/hlist_bl based hash for quotas

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Prior to this patch, GFS2 kept all the quotas for each super block in a single linked list. This is rather slow when there are large numbers of quotas.

This patch introduces a hlist_bl based hash table, similar to the one used for glocks. The initial look up of the quota is now lockless in the case where it is already cached, although we still have to take the per quota spinlock in order to bump the ref count. Either way though, this is a big improvement on what was there before.

The qd_lock and the per super block list is preserved, for the time being. However it is intended that since this is no longer used for its original role, it should be possible to shrink the number of items on that list in due course and remove the requirement to take qd_lock in qd_get.

Signed-off-by Steven Whitehouse <[email protected]>
Cc Abhijith Das <[email protected]>
Cc Paul E. McKenney <[email protected]>
fs/gfs2/incore.h +4 -0
index a99f60c..59d99ec 100644
@@ -428,10 +428,13 @@ enum {
 };
 
 struct gfs2_quota_data {
+	struct hlist_bl_node qd_hlist;
 	struct list_head qd_list;
 	struct kqid qd_id;
+	struct gfs2_sbd *qd_sbd;
 	struct lockref qd_lockref;
 	struct list_head qd_lru;
+	unsigned qd_hash;
 
 	unsigned long qd_flags;		/* QDF_... */
 

@@ -450,6 +453,7 @@ struct gfs2_quota_data {
 
 	u64 qd_sync_gen;
 	unsigned long qd_last_warn;
+	struct rcu_head qd_rcu;
 };
 
 struct gfs2_trans {
fs/gfs2/main.c +1 -0
index 0650db2..c272e73 100644
@@ -76,6 +76,7 @@ static int __init init_gfs2_fs(void)
 
 	gfs2_str2qstr(&gfs2_qdot, ".");
 	gfs2_str2qstr(&gfs2_qdotdot, "..");
+	gfs2_quota_hash_init();
 
 	error = gfs2_sys_init();
 	if (error)
fs/gfs2/quota.c +120 -48

273 lines not on this page · raw message

fs/gfs2/quota.h +1 -0
index 96e4f34..55d506e 100644
@@ -57,5 +57,6 @@ static inline int gfs2_quota_lock_check(struct gfs2_inode *ip)
 extern const struct quotactl_ops gfs2_quotactl_ops;
 extern struct shrinker gfs2_qd_shrinker;
 extern struct list_lru gfs2_qd_lru;
+extern void __init gfs2_quota_hash_init(void);
 
 #endif /* __QUOTA_DOT_H__ */
Signature · 1 line
1.8.3.1