balance_level() may return early in some cases, but these checks don't
have to be done with blocking write lock.
This puts together these checks into a helper and the benefit is to
avoid switching spinning locks to blocking locks (in these paticular
cases) which slows down btrfs overall.
Signed-off-by: Liu Bo <bo....@linux.alibaba.com>
---
fs/btrfs/ctree.c | 41 ++++++++++++++++++++++++++++++-----------
1 file changed, 30 insertions(+), 11 deletions(-)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 858085490e23..ba267a069ca1 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1758,6 +1758,29 @@ static void root_sub_used(struct btrfs_root *root, u32
size)
return eb;
}
+static bool need_balance_level(struct btrfs_fs_info *fs_info,
+ struct btrfs_trans_handle *trans,
+ struct btrfs_path *path, int level)
+{
+ struct extent_buffer *mid;
+
+ mid = path->nodes[level];
+
+ WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK &&
+ path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING);
+ WARN_ON(btrfs_header_generation(mid) != trans->transid);
+
+ /* If mid is the root node. */
+ if (level < BTRFS_MAX_LEVEL - 1 && path->nodes[level + 1] == NULL)
+ if (btrfs_header_nritems(mid) != 1)
+ return false;
+
+ if (btrfs_header_nritems(mid) > BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
+ return false;
+
+ return true;
+}
+
/*
* node level balancing, used to make sure nodes are in proper order for
* item deletion. We balance from the top down, so we have to make sure
@@ -1780,10 +1803,6 @@ static noinline int balance_level(struct
btrfs_trans_handle *trans,
mid = path->nodes[level];
- WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK &&
- path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING);
- WARN_ON(btrfs_header_generation(mid) != trans->transid);
-
orig_ptr = btrfs_node_blockptr(mid, orig_slot);
if (level < BTRFS_MAX_LEVEL - 1) {
@@ -1798,9 +1817,6 @@ static noinline int balance_level(struct
btrfs_trans_handle *trans,
if (!parent) {
struct extent_buffer *child;
- if (btrfs_header_nritems(mid) != 1)
- return 0;
-
/* promote the child to a root */
child = read_node_slot(fs_info, mid, 0);
if (IS_ERR(child)) {
@@ -1838,9 +1854,6 @@ static noinline int balance_level(struct
btrfs_trans_handle *trans,
free_extent_buffer_stale(mid);
return 0;
}
- if (btrfs_header_nritems(mid) >
- BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
- return 0;
left = read_node_slot(fs_info, parent, pslot - 1);
if (IS_ERR(left))
@@ -2460,14 +2473,20 @@ noinline void btrfs_unlock_up_safe(struct btrfs_path
*path, int level)
goto again;
}
+ /* Skip setting path to blocking if balance is not needed. */
+ if (!need_balance_level(fs_info, trans, p, level)) {
+ ret = 0;
+ goto done;
+ }
+
btrfs_set_path_blocking(p);
reada_for_balance(fs_info, p, level);
sret = balance_level(trans, root, p, level);
-
if (sret) {
ret = sret;
goto done;
}
+
b = p->nodes[level];
if (!b) {
btrfs_release_path(p);
--
1.8.3.1
