From 19fd6231279be3c3bdd02ed99f9b0eb195978064 Mon Sep 17 00:00:00 2001
From: Nick Piggin <npiggin@suse.de>
Date: Fri, 25 Jul 2008 19:45:32 -0700
Subject: mm: spinlock tree_lock

mapping->tree_lock has no read lockers.  convert the lock from an rwlock
to a spinlock.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Reviewed-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/swapfile.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'mm/swapfile.c')

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 2f33edb8bee9..af283933c14e 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -369,13 +369,13 @@ int remove_exclusive_swap_page(struct page *page)
 	retval = 0;
 	if (p->swap_map[swp_offset(entry)] == 1) {
 		/* Recheck the page count with the swapcache lock held.. */
-		write_lock_irq(&swapper_space.tree_lock);
+		spin_lock_irq(&swapper_space.tree_lock);
 		if ((page_count(page) == 2) && !PageWriteback(page)) {
 			__delete_from_swap_cache(page);
 			SetPageDirty(page);
 			retval = 1;
 		}
-		write_unlock_irq(&swapper_space.tree_lock);
+		spin_unlock_irq(&swapper_space.tree_lock);
 	}
 	spin_unlock(&swap_lock);
 
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