4 files changed, 58 insertions, 6 deletions

diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
index 9dd68cd7b0ad..96f8ca6b3aba 100644
--- a/fs/ocfs2/alloc.c
+++ b/fs/ocfs2/alloc.c
@@ -5169,12 +5169,12 @@ out:
  *
  * The caller is responsible for passing down meta_ac if we'll need it.
  */
-static int ocfs2_change_extent_flag(handle_t *handle,
-                                    struct ocfs2_extent_tree *et,
-                                    u32 cpos, u32 len, u32 phys,
-                                    struct ocfs2_alloc_context *meta_ac,
-                                    struct ocfs2_cached_dealloc_ctxt *dealloc,
-                                    int new_flags, int clear_flags)
+int ocfs2_change_extent_flag(handle_t *handle,
+                             struct ocfs2_extent_tree *et,
+                             u32 cpos, u32 len, u32 phys,
+                             struct ocfs2_alloc_context *meta_ac,
+                             struct ocfs2_cached_dealloc_ctxt *dealloc,
+                             int new_flags, int clear_flags)
 {
         int ret, index;
         struct super_block *sb = ocfs2_metadata_cache_get_super(et->et_ci);
diff --git a/fs/ocfs2/alloc.h b/fs/ocfs2/alloc.h
index 0610ba148ea0..19d5b88a93df 100644
--- a/fs/ocfs2/alloc.h
+++ b/fs/ocfs2/alloc.h
@@ -128,6 +128,12 @@ int ocfs2_mark_extent_written(struct inode *inode,
                               handle_t *handle, u32 cpos, u32 len, u32 phys,
                               struct ocfs2_alloc_context *meta_ac,
                               struct ocfs2_cached_dealloc_ctxt *dealloc);
+int ocfs2_change_extent_flag(handle_t *handle,
+                             struct ocfs2_extent_tree *et,
+                             u32 cpos, u32 len, u32 phys,
+                             struct ocfs2_alloc_context *meta_ac,
+                             struct ocfs2_cached_dealloc_ctxt *dealloc,
+                             int new_flags, int clear_flags);
 int ocfs2_remove_extent(handle_t *handle, struct ocfs2_extent_tree *et,
                         u32 cpos, u32 len,
                         struct ocfs2_alloc_context *meta_ac,
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index bb5357376ef5..eae404602424 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -516,6 +516,13 @@ static inline void ocfs2_add_links_count(struct ocfs2_dinode *di, int n)
         ocfs2_set_links_count(di, links);
 }
 
+static inline int ocfs2_refcount_tree(struct ocfs2_super *osb)
+{
+        if (osb->s_feature_incompat & OCFS2_FEATURE_INCOMPAT_REFCOUNT_TREE)
+                return 1;
+        return 0;
+}
+
 /* set / clear functions because cluster events can make these happen
  * in parallel so we want the transitions to be atomic. this also
  * means that any future flags osb_flags must be protected by spinlock
diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 2c7974cccaf8..f7d19f4db897 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -2153,3 +2153,42 @@ out:
         brelse(ref_root_bh);
         return ret;
 }
+
+/*
+ * Mark the already-existing extent at cpos as refcounted for len clusters.
+ * This adds the refcount extent flag.
+ *
+ * If the existing extent is larger than the request, initiate a
+ * split. An attempt will be made at merging with adjacent extents.
+ *
+ * The caller is responsible for passing down meta_ac if we'll need it.
+ */
+static int ocfs2_mark_extent_refcounted(struct inode *inode,
+                                struct ocfs2_extent_tree *et,
+                                handle_t *handle, u32 cpos,
+                                u32 len, u32 phys,
+                                struct ocfs2_alloc_context *meta_ac,
+                                struct ocfs2_cached_dealloc_ctxt *dealloc)
+{
+        int ret;
+
+        mlog(0, "Inode %lu refcount tree cpos %u, len %u, phys cluster %u\n",
+             inode->i_ino, cpos, len, phys);
+
+        if (!ocfs2_refcount_tree(OCFS2_SB(inode->i_sb))) {
+                ocfs2_error(inode->i_sb, "Inode %lu want to use refcount "
+                            "tree, but the feature bit is not set in the "
+                            "super block.", inode->i_ino);
+                ret = -EROFS;
+                goto out;
+        }
+
+        ret = ocfs2_change_extent_flag(handle, et, cpos,
+                                       len, phys, meta_ac, dealloc,
+                                       OCFS2_EXT_REFCOUNTED, 0);
+        if (ret)
+                mlog_errno(ret);
+
+out:
+        return ret;
+}