This is a helper function to test if two states are adjacent.
It is used for applying rwlock for extent state.
Signed-off-by: Liu Bo <liubo2...@cn.fujitsu.com>
---
fs/btrfs/extent_io.c | 27 +++++++++++++++++++++++++++
1 files changed, 27 insertions(+), 0 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 1858d86..4c6dd85 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -473,6 +473,33 @@ void extent_io_tree_panic(struct extent_io_tree *tree, int
err)
"thread while locked.");
}
+static int test_merge_state(struct extent_io_tree *tree,
+ struct extent_state *state)
+{
+ struct extent_state *other;
+ struct rb_node *other_node;
+
+ if (state->state & (EXTENT_IOBITS | EXTENT_BOUNDARY))
+ return 0;
+
+ other_node = rb_prev(&state->rb_node);
+ if (other_node) {
+ other = rb_entry(other_node, struct extent_state, rb_node);
+ if (other->end == state->start - 1 &&
+ other->state == state->state)
+ return 1;
+ }
+ other_node = rb_next(&state->rb_node);
+ if (other_node) {
+ other = rb_entry(other_node, struct extent_state, rb_node);
+ if (other->start == state->end + 1 &&
+ other->state == state->state)
+ return 1;
+ }
+
+ return 0;
+}
+
/*
* clear some bits on a range in the tree. This may require splitting
* or inserting elements in the tree, so the gfp mask is used to
--
1.6.5.2
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