From 4c71f98704857f91b42f354034e9fc7fd3b14c6e Mon Sep 17 00:00:00 2001
From: Chris Mason <chris.mason@oracle.com>
Date: Mon, 10 Nov 2008 13:08:31 -0500
Subject: [PATCH] --- yaml --- r: 129011 b: refs/heads/master c:
 240d5d482b69415b92ffce4b8dfca10799c9890b h: refs/heads/master i:   129009:
 7c62ac6c5abbce66c8aace495155d83447d5ba45   129007:
 0e3d2fb6edf5b40aaf2d0cb52e23226c053a7494 v: v3

---
 [refs]                   |  2 +-
 trunk/fs/btrfs/disk-io.c | 10 ++++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index cb9ea6375668..3aa9914ed955 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: b47eda8690a10f4fc01eb7b795078fa3fa57149f
+refs/heads/master: 240d5d482b69415b92ffce4b8dfca10799c9890b
diff --git a/trunk/fs/btrfs/disk-io.c b/trunk/fs/btrfs/disk-io.c
index 8efc123d222b..1bb54d69fbb2 100644
--- a/trunk/fs/btrfs/disk-io.c
+++ b/trunk/fs/btrfs/disk-io.c
@@ -1201,6 +1201,16 @@ void btrfs_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
 		return;
 
 	inode = mapping->host;
+
+	/*
+	 * don't do the expensive searching for a small number of
+	 * devices
+	 */
+	if (BTRFS_I(inode)->root->fs_info->fs_devices->open_devices <= 2) {
+		__unplug_io_fn(bdi, page);
+		return;
+	}
+
 	offset = page_offset(page);
 
 	em_tree = &BTRFS_I(inode)->extent_tree;