Btrfs: implement memory reclaim for leaf reference cache
The memory reclaiming issue happens when snapshot exists. In that
case, some cache entries may not be used during old snapshot dropping,
so they will remain in the cache until umount.
The patch adds a field to struct btrfs_leaf_ref to record create time. Besides,
the patch makes all dead roots of a given snapshot linked together in order of
create time. After a old snapshot was completely dropped, we check the dead
root list and remove all cache entries created before the oldest dead root in
the list.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ref-cache.h b/fs/btrfs/ref-cache.h
index 823c049..c361b32 100644
--- a/fs/btrfs/ref-cache.h
+++ b/fs/btrfs/ref-cache.h
@@ -30,6 +30,7 @@
int in_tree;
atomic_t usage;
+ u64 root_gen;
u64 bytenr;
u64 owner;
u64 generation;
@@ -41,14 +42,13 @@
static inline size_t btrfs_leaf_ref_size(int nr_extents)
{
- return sizeof(struct btrfs_leaf_ref) +
+ return sizeof(struct btrfs_leaf_ref) +
sizeof(struct btrfs_extent_info) * nr_extents;
}
static inline void btrfs_leaf_ref_tree_init(struct btrfs_leaf_ref_tree *tree)
{
tree->root.rb_node = NULL;
- tree->last = NULL;
INIT_LIST_HEAD(&tree->list);
spin_lock_init(&tree->lock);
}
@@ -59,12 +59,13 @@
}
void btrfs_leaf_ref_tree_init(struct btrfs_leaf_ref_tree *tree);
-struct btrfs_leaf_ref *btrfs_alloc_leaf_ref(int nr_extents);
-void btrfs_free_leaf_ref(struct btrfs_leaf_ref *ref);
+struct btrfs_leaf_ref *btrfs_alloc_leaf_ref(struct btrfs_root *root,
+ int nr_extents);
+void btrfs_free_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref);
struct btrfs_leaf_ref *btrfs_lookup_leaf_ref(struct btrfs_root *root,
u64 bytenr);
int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref);
-int btrfs_remove_leaf_refs(struct btrfs_root *root);
+int btrfs_remove_leaf_refs(struct btrfs_root *root, u64 max_root_gen);
int btrfs_remove_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref);
#endif