From: jxiong <jxiong>
Date: Fri, 18 Sep 2009 05:00:23 +0000 (+0000)
Subject: b=19537
X-Git-Tag: v1_9_270~31
X-Git-Url: https://git.whamcloud.com/?p=fs%2Flustre-release.git;a=commitdiff_plain;h=c7f0a3e01d2691a3208b586c0de1f1afbf79b82e

b=19537
r=rread

Use atomic_dec_and_lock() so that if it is NOT the last refcount, it doesn't need to take the lock.
---

diff --git a/lustre/obdclass/cl_page.c b/lustre/obdclass/cl_page.c
index 0e09051..55887f9 100644
--- a/lustre/obdclass/cl_page.c
+++ b/lustre/obdclass/cl_page.c
@@ -630,8 +630,7 @@ void cl_page_put(const struct lu_env *env, struct cl_page *page)
         CL_PAGE_HEADER(D_TRACE, env, page, "%i\n", atomic_read(&page->cp_ref));
 
         hdr = cl_object_header(cl_object_top(page->cp_obj));
-        spin_lock(&hdr->coh_page_guard);
-        if (atomic_dec_and_test(&page->cp_ref)) {
+        if (atomic_dec_and_lock(&page->cp_ref, &hdr->coh_page_guard)) {
                 atomic_dec(&site->cs_pages.cs_busy);
                 /* We're going to access the page w/o a reference, but it's
                  * ok because we have grabbed the lock coh_page_guard, which
@@ -656,8 +655,8 @@ void cl_page_put(const struct lu_env *env, struct cl_page *page)
                         EXIT;
                         return;
                 }
+                spin_unlock(&hdr->coh_page_guard);
         }
-        spin_unlock(&hdr->coh_page_guard);
 
         EXIT;
 }