[PATCH 2/6 v3][RFC] Btrfs: add helper function to test if we can merge state
From: Liu Bo <hidden>
Date: 2012-07-25 05:59:41
Subsystem:
btrfs file system, filesystems (vfs and infrastructure), the rest · Maintainers:
Chris Mason, David Sterba, Alexander Viro, Christian Brauner, Linus Torvalds
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 <redacted> --- 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
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1.6.5.2