dlm: use kref_put_lock in put_rsb

Alexander Aring · teigland · commit 9502a7f688fe · 2022-05-02T11:22:56.000-05:00
This patch will optimize put_rsb() by using kref_put_lock(). The
function kref_put_lock() will only take the lock if the reference is
going to be zero, if not the lock will never be held.

Signed-off-by: Alexander Aring &lt;aahringo@redhat.com&gt;
Signed-off-by: David Teigland &lt;teigland@redhat.com&gt;
diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
@@ -350,10 +350,12 @@ static void put_rsb(struct dlm_rsb *r)
 {
 	struct dlm_ls *ls = r->res_ls;
 	uint32_t bucket = r->res_bucket;
+	int rv;
 
-	spin_lock(&ls->ls_rsbtbl[bucket].lock);
-	kref_put(&r->res_ref, toss_rsb);
-	spin_unlock(&ls->ls_rsbtbl[bucket].lock);
+	rv = kref_put_lock(&r->res_ref, toss_rsb,
+			   &ls->ls_rsbtbl[bucket].lock);
+	if (rv)
+		spin_unlock(&ls->ls_rsbtbl[bucket].lock);
 }
 
 void dlm_put_rsb(struct dlm_rsb *r)

Original file line number	Diff line number	Diff line change
`@@ -350,10 +350,12 @@ static void put_rsb(struct dlm_rsb *r)`
`350`	`350`	`{`
`351`	`351`	`struct dlm_ls *ls = r->res_ls;`
`352`	`352`	`uint32_t bucket = r->res_bucket;`
	`353`	`+ int rv;`
`353`	`354`
`354`		`- spin_lock(&ls->ls_rsbtbl[bucket].lock);`
`355`		`- kref_put(&r->res_ref, toss_rsb);`
`356`		`- spin_unlock(&ls->ls_rsbtbl[bucket].lock);`
	`355`	`+ rv = kref_put_lock(&r->res_ref, toss_rsb,`
	`356`	`+ &ls->ls_rsbtbl[bucket].lock);`
	`357`	`+ if (rv)`
	`358`	`+ spin_unlock(&ls->ls_rsbtbl[bucket].lock);`
`357`	`359`	`}`
`358`	`360`
`359`	`361`	`void dlm_put_rsb(struct dlm_rsb *r)`