From a1af8fb1eaa08e55f6e0799779a89f455a5017f2 Mon Sep 17 00:00:00 2001
From: Brian Behlendorf <behlendorf1@llnl.gov>
Date: Tue, 30 Oct 2012 11:21:42 -0700
Subject: [PATCH] Optimize spl_kmem_cache_free()

Because only virtual slabs may have emergency objects and these
objects are guaranteed to have physical addresses.  It can be
easily determined if the passed object is a virtual slab object
or an emergency object.  This allows us to completely optimize
the emergency object free case out of the common free path.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
---
 module/spl/spl-kmem.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/module/spl/spl-kmem.c b/module/spl/spl-kmem.c
index 7e68522ad3..5627b5590b 100644
--- a/module/spl/spl-kmem.c
+++ b/module/spl/spl-kmem.c
@@ -2023,11 +2023,12 @@ spl_kmem_cache_free(spl_kmem_cache_t *skc, void *obj)
 	atomic_inc(&skc->skc_ref);
 
 	/*
-	 * Emergency objects are never part of the virtual address space
-	 * so if we get a virtual address we can optimize this check out.
+	 * Only virtual slabs may have emergency objects and these objects
+	 * are guaranteed to have physical addresses.  They must be removed
+	 * from the tree of emergency objects and the freed.
 	 */
-	if (!kmem_virt(obj) && !spl_emergency_free(skc, obj))
-		SGOTO(out, 0);
+	if ((skc->skc_flags & KMC_VMEM) && !kmem_virt(obj))
+		SGOTO(out, spl_emergency_free(skc, obj));
 
 	local_irq_save(flags);