From: Liu Bo <liubo2009@cn.fujitsu.com>
Date: Thu, 16 Feb 2012 10:34:37 +0000 (+0800)
Subject: Btrfs: skip states when they does not contain bits to clear
X-Git-Tag: v3.12-rc1~3717^2~11
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=0449314a9cc5a7fb0bd42e2175a3c46f68f3a2b0;p=kernel%2Fkernel-generic.git

Btrfs: skip states when they does not contain bits to clear

Clearing a range's bits is different with setting them, since we don't
need to touch them when states do not contain bits we want.

Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
---

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 8d6f55f..fe14285 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -513,6 +513,15 @@ hit_next:
 	WARN_ON(state->end < start);
 	last_end = state->end;
 
+	if (state->end < end && !need_resched())
+		next_node = rb_next(&state->rb_node);
+	else
+		next_node = NULL;
+
+	/* the state doesn't have the wanted bits, go ahead */
+	if (!(state->state & bits))
+		goto next;
+
 	/*
 	 *     | ---- desired range ---- |
 	 *  | state | or
@@ -565,12 +574,8 @@ hit_next:
 		goto out;
 	}
 
-	if (state->end < end && prealloc && !need_resched())
-		next_node = rb_next(&state->rb_node);
-	else
-		next_node = NULL;
-
 	set |= clear_state_bit(tree, state, &bits, wake);
+next:
 	if (last_end == (u64)-1)
 		goto out;
 	start = last_end + 1;