From de2a7581cb29543b0bcce8511d435ab4a17d20e1 Mon Sep 17 00:00:00 2001
From: Li Zefan <lizf@cn.fujitsu.com>
Date: Mon, 12 Mar 2012 16:39:48 +0800
Subject: [PATCH] --- yaml --- r: 299803 b: refs/heads/master c:
 cdc6a3952558f00b1bc3b6401e1cf98797632fe2 h: refs/heads/master i:   299801:
 9d6b5cd99d7b6a1554319a6c63453050b72451cd   299799:
 fb9388b6d157d66435d024a21f93667335f5b340 v: v3

---
 [refs]                     |  2 +-
 trunk/fs/btrfs/extent_io.c | 36 +++++++++++++++++++++---------------
 2 files changed, 22 insertions(+), 16 deletions(-)

diff --git a/[refs] b/[refs]
index 145a959e86f5..a5f8a1ced90b 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8e52acf70459020d7e9e9fda25066be4da520943
+refs/heads/master: cdc6a3952558f00b1bc3b6401e1cf98797632fe2
diff --git a/trunk/fs/btrfs/extent_io.c b/trunk/fs/btrfs/extent_io.c
index 05951bdf72cc..11eeb81fe695 100644
--- a/trunk/fs/btrfs/extent_io.c
+++ b/trunk/fs/btrfs/extent_io.c
@@ -402,6 +402,15 @@ static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
 	return 0;
 }
 
+static struct extent_state *next_state(struct extent_state *state)
+{
+	struct rb_node *next = rb_next(&state->rb_node);
+	if (next)
+		return rb_entry(next, struct extent_state, rb_node);
+	else
+		return NULL;
+}
+
 /*
  * utility function to clear some bits in an extent state struct.
  * it will optionally wake up any one waiting on this state (wake == 1)
@@ -409,10 +418,11 @@ static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
  * If no bits are set on the state struct after clearing things, the
  * struct is freed and removed from the tree
  */
-static void clear_state_bit(struct extent_io_tree *tree,
-			    struct extent_state *state,
-			    int *bits, int wake)
+static struct extent_state *clear_state_bit(struct extent_io_tree *tree,
+					    struct extent_state *state,
+					    int *bits, int wake)
 {
+	struct extent_state *next;
 	int bits_to_clear = *bits & ~EXTENT_CTLBITS;
 
 	if ((bits_to_clear & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) {
@@ -425,6 +435,7 @@ static void clear_state_bit(struct extent_io_tree *tree,
 	if (wake)
 		wake_up(&state->wq);
 	if (state->state == 0) {
+		next = next_state(state);
 		if (state->tree) {
 			rb_erase(&state->rb_node, &tree->state);
 			state->tree = NULL;
@@ -434,7 +445,9 @@ static void clear_state_bit(struct extent_io_tree *tree,
 		}
 	} else {
 		merge_state(tree, state);
+		next = next_state(state);
 	}
+	return next;
 }
 
 static struct extent_state *
@@ -473,7 +486,6 @@ int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 	struct extent_state *state;
 	struct extent_state *cached;
 	struct extent_state *prealloc = NULL;
-	struct rb_node *next_node;
 	struct rb_node *node;
 	u64 last_end;
 	int err;
@@ -525,14 +537,11 @@ int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 	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))
+	if (!(state->state & bits)) {
+		state = next_state(state);
 		goto next;
+	}
 
 	/*
 	 *     | ---- desired range ---- |
@@ -590,16 +599,13 @@ int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 		goto out;
 	}
 
-	clear_state_bit(tree, state, &bits, wake);
+	state = clear_state_bit(tree, state, &bits, wake);
 next:
 	if (last_end == (u64)-1)
 		goto out;
 	start = last_end + 1;
-	if (start <= end && next_node) {
-		state = rb_entry(next_node, struct extent_state,
-				 rb_node);
+	if (start <= end && state && !need_resched())
 		goto hit_next;
-	}
 	goto search_again;
 
 out: