[PATCH 12/19] btrfs: Rename remove_backref_node() to cleanup_backref_node() and move it to backref.c

Qu Wenruo
2020-03-03T07:15:39Z

Also add comment explaining the cleanup progress, to differ it from
drop_backref_node().

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
fs/btrfs/backref.c | 38 ++++++++++++++++++++++++++++++++
fs/btrfs/backref.h | 9 ++++++++
fs/btrfs/relocation.c | 51 ++++---------------------------------------
3 files changed, 51 insertions(+), 47 deletions(-)

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 7511ce8447e8..4f0e8ab1d9cf 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -2490,3 +2490,41 @@ struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
cache->nr_edges++;
return edge;
}
+
+void cleanup_backref_node(struct backref_cache *cache,
+ struct backref_node *node)
+{
+ struct backref_node *upper;
+ struct backref_edge *edge;
+
+ if (!node)
+ return;
+
+ BUG_ON(!node->lowest && !node->detached);
+ while (!list_empty(&node->upper)) {
+ edge = list_entry(node->upper.next, struct backref_edge,
+ list[LOWER]);
+ upper = edge->node[UPPER];
+ list_del(&edge->list[LOWER]);
+ list_del(&edge->list[UPPER]);
+ free_backref_edge(cache, edge);
+
+ if (RB_EMPTY_NODE(&upper->rb_node)) {
+ BUG_ON(!list_empty(&node->upper));
+ drop_backref_node(cache, node);
+ node = upper;
+ node->lowest = 1;
+ continue;
+ }
+ /*
+ * add the node to leaf node list if no other
+ * child block cached.
+ */
+ if (list_empty(&upper->lower)) {
+ list_add_tail(&upper->lower, &cache->leaves);
+ upper->lowest = 1;
+ }
+ }
+
+ drop_backref_node(cache, node);
+}
diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
index 7b8bf4e13d99..1c34a8dbee2f 100644
--- a/fs/btrfs/backref.h
+++ b/fs/btrfs/backref.h
@@ -368,4 +368,13 @@ static inline void drop_backref_node(struct backref_cache *tree,
free_backref_node(tree, node);
}

+/*
+ * Drop the backref node from cache, also cleaning up all its
+ * upper edges and any uncached nodes in the path.
+ *
+ * This cleanup happens bottom up, thus the node should either
+ * be the lowest node in the cache or detached node.
+ */
+void cleanup_backref_node(struct backref_cache *cache,
+ struct backref_node *node);
#endif
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 1c038428990c..2050414884fb 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -161,9 +161,6 @@ struct reloc_control {
#define MOVE_DATA_EXTENTS 0
#define UPDATE_DATA_PTRS 1

-static void remove_backref_node(struct backref_cache *cache,
- struct backref_node *node);
-
static void mark_block_processed(struct reloc_control *rc,
struct backref_node *node)
{
@@ -193,13 +190,13 @@ static void backref_cache_cleanup(struct backref_cache *cache)
while (!list_empty(&cache->detached)) {
node = list_entry(cache->detached.next,
struct backref_node, list);
- remove_backref_node(cache, node);
+ cleanup_backref_node(cache, node);
}

while (!list_empty(&cache->leaves)) {
node = list_entry(cache->leaves.next,
struct backref_node, lower);
- remove_backref_node(cache, node);
+ cleanup_backref_node(cache, node);
}

cache->last_trans = 0;
@@ -275,46 +272,6 @@ static struct backref_node *walk_down_backref(struct backref_edge *edges[],
*index = 0;
return NULL;
}
-/*
- * remove a backref node from the backref cache
- */
-static void remove_backref_node(struct backref_cache *cache,
- struct backref_node *node)
-{
- struct backref_node *upper;
- struct backref_edge *edge;
-
- if (!node)
- return;
-
- BUG_ON(!node->lowest && !node->detached);
- while (!list_empty(&node->upper)) {
- edge = list_entry(node->upper.next, struct backref_edge,
- list[LOWER]);
- upper = edge->node[UPPER];
- list_del(&edge->list[LOWER]);
- list_del(&edge->list[UPPER]);
- free_backref_edge(cache, edge);
-
- if (RB_EMPTY_NODE(&upper->rb_node)) {
- BUG_ON(!list_empty(&node->upper));
- drop_backref_node(cache, node);
- node = upper;
- node->lowest = 1;
- continue;
- }
- /*
- * add the node to leaf node list if no other
- * child block cached.
- */
- if (list_empty(&upper->lower)) {
- list_add_tail(&upper->lower, &cache->leaves);
- upper->lowest = 1;
- }
- }
-
- drop_backref_node(cache, node);
-}

static void update_backref_node(struct backref_cache *cache,
struct backref_node *node, u64 bytenr)
@@ -352,7 +309,7 @@ static int update_backref_cache(struct btrfs_trans_handle *trans,
while (!list_empty(&cache->detached)) {
node = list_entry(cache->detached.next,
struct backref_node, list);
- remove_backref_node(cache, node);
+ cleanup_backref_node(cache, node);
}

while (!list_empty(&cache->changed)) {
@@ -2989,7 +2946,7 @@ static int relocate_tree_block(struct btrfs_trans_handle *trans,
}
out:
if (ret || node->level == 0 || node->cowonly)
- remove_backref_node(&rc->backref_cache, node);
+ cleanup_backref_node(&rc->backref_cache, node);
return ret;
}

--
2.25.1