ceph: keep leaf frag when updating fragtree

Nodes in i_fragtree are sorted according to ceph_compare_frag().
It means frag node in i_fragtree always follow its direct parent
node. To check if a leaf node is valid, we just need to check if
it's child of previous split node.

Signed-off-by: Yan, Zheng <zyan@redhat.com>

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 562f57d15f46da29a687beabeafb205d6713c75a..09713f32ea88e15bdeaafff2d94f483a4d05f505 100644 (file)
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -310,12 +310,21 @@ static int frag_tree_split_cmp(const void *l, const void *r)
        return ceph_frag_compare(ls->frag, rs->frag);
 }
 
+static bool is_frag_child(u32 f, struct ceph_inode_frag *frag)
+{
+       if (!frag)
+               return f == ceph_frag_make(0, 0);
+       if (ceph_frag_bits(f) != ceph_frag_bits(frag->frag) + frag->split_by)
+               return false;
+       return ceph_frag_contains_value(frag->frag, ceph_frag_value(f));
+}
+
 static int ceph_fill_fragtree(struct inode *inode,
                              struct ceph_frag_tree_head *fragtree,
                              struct ceph_mds_reply_dirfrag *dirinfo)
 {
        struct ceph_inode_info *ci = ceph_inode(inode);
-       struct ceph_inode_frag *frag;
+       struct ceph_inode_frag *frag, *prev_frag = NULL;
        struct rb_node *rb_node;
        int i;
        u32 id, nsplits;
@@ -362,8 +371,12 @@ static int ceph_fill_fragtree(struct inode *inode,
                                break;
                        }
                        rb_node = rb_next(rb_node);
-                       rb_erase(&frag->node, &ci->i_fragtree);
-                       kfree(frag);
+                       /* delete stale split/leaf node */
+                       if (frag->split_by > 0 ||
+                           !is_frag_child(frag->frag, prev_frag)) {
+                               rb_erase(&frag->node, &ci->i_fragtree);
+                               kfree(frag);
+                       }
                        frag = NULL;
                }
                if (!frag) {
@@ -373,12 +386,17 @@ static int ceph_fill_fragtree(struct inode *inode,
                }
                frag->split_by = le32_to_cpu(fragtree->splits[i].by);
                dout(" frag %x split by %d\n", frag->frag, frag->split_by);
+               prev_frag = frag;
        }
        while (rb_node) {
                frag = rb_entry(rb_node, struct ceph_inode_frag, node);
                rb_node = rb_next(rb_node);
-               rb_erase(&frag->node, &ci->i_fragtree);
-               kfree(frag);
+               /* delete stale split/leaf node */
+               if (frag->split_by > 0 ||
+                   !is_frag_child(frag->frag, prev_frag)) {
+                       rb_erase(&frag->node, &ci->i_fragtree);
+                       kfree(frag);
+               }
        }
 out_unlock:
        mutex_unlock(&ci->i_fragtree_mutex);