From: Zhao Lei <zhaolei@xxxxxxxxxxxxxx>
This patch include following modify:
1: It isn't necessary to use following type of goto statement:
if (cow) {
if (!should_cow_block(trans, root, b))
goto cow_done;
...
}
cow_done:
...
2: Updating of p->nodes[level] is only necessary on cow.
we move these code into if (cow) {} block.
3: Updating of level and p->locks[level] is only necessary when
level is changed, so we avoid no-use operation in old code.
4: Add a unlikely() for rare case.
Signed-off-by: Zhao Lei <zhaolei@xxxxxxxxxxxxxx>
Signed-off-by: Miao Xie <miaox@xxxxxxxxxxxxxx>
---
fs/btrfs/ctree.c | 34 ++++++++++++++++------------------
1 files changed, 16 insertions(+), 18 deletions(-)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index c4bc570..4f258ba 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1724,15 +1724,12 @@ again:
if (!p->skip_locking)
p->locks[level] = 1;
- if (cow) {
- /*
- * if we don't really need to cow this block
- * then we don't want to set the path blocking,
- * so we test it here
- */
- if (!should_cow_block(trans, root, b))
- goto cow_done;
-
+ /*
+ * if we don't really need to cow this block
+ * then we don't want to set the path blocking,
+ * so we test it here
+ */
+ if (cow && should_cow_block(trans, root, b)) {
btrfs_set_path_blocking(p);
err = btrfs_cow_block(trans, root, b,
@@ -1743,17 +1740,18 @@ again:
ret = err;
goto done;
}
- }
-cow_done:
- BUG_ON(!cow && ins_len);
- if (level != btrfs_header_level(b))
- WARN_ON(1);
- level = btrfs_header_level(b);
- p->nodes[level] = b;
- if (!p->skip_locking)
- p->locks[level] = 1;
+ if (unlikely(level != btrfs_header_level(b))) {
+ WARN_ON(1);
+ level = btrfs_header_level(b);
+ if (!p->skip_locking)
+ p->locks[level] = 1;
+ }
+ p->nodes[level] = b;
+ }
+
+ BUG_ON(!cow && ins_len);
btrfs_clear_path_blocking(p, NULL);
/*
--
1.6.5.2
--
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