Btrfs: mark delayed refs as for cow

Add a for_cow parameter to add_delayed_*_ref and pass the appropriate value
from every call site. The for_cow parameter will later on be used to
determine if a ref will change anything with respect to qgroups.

Delayed refs coming from relocation are always counted as for_cow, as they
don't change subvol quota.

Also pass in the fs_info for later use.

btrfs_find_all_roots() will use this as an optimization, as changes that are
for_cow will not change anything with respect to which root points to a
certain leaf. Thus, we don't need to add the current sequence number to
those delayed refs.

Signed-off-by: Arne Jansen <sensille@gmx.net>
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

12 files changed, 155 insertions, 114 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index dede441bdeee..0639a555e16e 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -240,7 +240,7 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
 
         cow = btrfs_alloc_free_block(trans, root, buf->len, 0,
                                      new_root_objectid, &disk_key, level,
-                                     buf->start, 0);
+                                     buf->start, 0, 1);
         if (IS_ERR(cow))
                 return PTR_ERR(cow);
 
@@ -261,9 +261,9 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
 
         WARN_ON(btrfs_header_generation(buf) > trans->transid);
         if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
-                ret = btrfs_inc_ref(trans, root, cow, 1);
+                ret = btrfs_inc_ref(trans, root, cow, 1, 1);
         else
-                ret = btrfs_inc_ref(trans, root, cow, 0);
+                ret = btrfs_inc_ref(trans, root, cow, 0, 1);
 
         if (ret)
                 return ret;
@@ -350,14 +350,14 @@ static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
                 if ((owner == root->root_key.objectid ||
                      root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
                     !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
-                        ret = btrfs_inc_ref(trans, root, buf, 1);
+                        ret = btrfs_inc_ref(trans, root, buf, 1, 1);
                         BUG_ON(ret);
 
                         if (root->root_key.objectid ==
                             BTRFS_TREE_RELOC_OBJECTID) {
-                                ret = btrfs_dec_ref(trans, root, buf, 0);
+                                ret = btrfs_dec_ref(trans, root, buf, 0, 1);
                                 BUG_ON(ret);
-                                ret = btrfs_inc_ref(trans, root, cow, 1);
+                                ret = btrfs_inc_ref(trans, root, cow, 1, 1);
                                 BUG_ON(ret);
                         }
                         new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
@@ -365,9 +365,9 @@ static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
 
                         if (root->root_key.objectid ==
                             BTRFS_TREE_RELOC_OBJECTID)
-                                ret = btrfs_inc_ref(trans, root, cow, 1);
+                                ret = btrfs_inc_ref(trans, root, cow, 1, 1);
                         else
-                                ret = btrfs_inc_ref(trans, root, cow, 0);
+                                ret = btrfs_inc_ref(trans, root, cow, 0, 1);
                         BUG_ON(ret);
                 }
                 if (new_flags != 0) {
@@ -381,11 +381,11 @@ static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
                 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
                         if (root->root_key.objectid ==
                             BTRFS_TREE_RELOC_OBJECTID)
-                                ret = btrfs_inc_ref(trans, root, cow, 1);
+                                ret = btrfs_inc_ref(trans, root, cow, 1, 1);
                         else
-                                ret = btrfs_inc_ref(trans, root, cow, 0);
+                                ret = btrfs_inc_ref(trans, root, cow, 0, 1);
                         BUG_ON(ret);
-                        ret = btrfs_dec_ref(trans, root, buf, 1);
+                        ret = btrfs_dec_ref(trans, root, buf, 1, 1);
                         BUG_ON(ret);
                 }
                 clean_tree_block(trans, root, buf);
@@ -446,7 +446,7 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
 
         cow = btrfs_alloc_free_block(trans, root, buf->len, parent_start,
                                      root->root_key.objectid, &disk_key,
-                                     level, search_start, empty_size);
+                                     level, search_start, empty_size, 1);
         if (IS_ERR(cow))
                 return PTR_ERR(cow);
 
@@ -484,7 +484,7 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
                 rcu_assign_pointer(root->node, cow);
 
                 btrfs_free_tree_block(trans, root, buf, parent_start,
-                                      last_ref);
+                                      last_ref, 1);
                 free_extent_buffer(buf);
                 add_root_to_dirty_list(root);
         } else {
@@ -500,7 +500,7 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
                                               trans->transid);
                 btrfs_mark_buffer_dirty(parent);
                 btrfs_free_tree_block(trans, root, buf, parent_start,
-                                      last_ref);
+                                      last_ref, 1);
         }
         if (unlock_orig)
                 btrfs_tree_unlock(buf);
@@ -957,7 +957,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
                 free_extent_buffer(mid);
 
                 root_sub_used(root, mid->len);
-                btrfs_free_tree_block(trans, root, mid, 0, 1);
+                btrfs_free_tree_block(trans, root, mid, 0, 1, 0);
                 /* once for the root ptr */
                 free_extent_buffer(mid);
                 return 0;
@@ -1015,7 +1015,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
                         if (wret)
                                 ret = wret;
                         root_sub_used(root, right->len);
-                        btrfs_free_tree_block(trans, root, right, 0, 1);
+                        btrfs_free_tree_block(trans, root, right, 0, 1, 0);
                         free_extent_buffer(right);
                         right = NULL;
                 } else {
@@ -1055,7 +1055,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
                 if (wret)
                         ret = wret;
                 root_sub_used(root, mid->len);
-                btrfs_free_tree_block(trans, root, mid, 0, 1);
+                btrfs_free_tree_block(trans, root, mid, 0, 1, 0);
                 free_extent_buffer(mid);
                 mid = NULL;
         } else {
@@ -2089,7 +2089,7 @@ static noinline int insert_new_root(struct btrfs_trans_handle *trans,
 
         c = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
                                    root->root_key.objectid, &lower_key,
-                                   level, root->node->start, 0);
+                                   level, root->node->start, 0, 0);
         if (IS_ERR(c))
                 return PTR_ERR(c);
 
@@ -2216,7 +2216,7 @@ static noinline int split_node(struct btrfs_trans_handle *trans,
 
         split = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
                                         root->root_key.objectid,
-                                        &disk_key, level, c->start, 0);
+                                        &disk_key, level, c->start, 0, 0);
         if (IS_ERR(split))
                 return PTR_ERR(split);
 
@@ -2970,7 +2970,7 @@ again:
 
         right = btrfs_alloc_free_block(trans, root, root->leafsize, 0,
                                         root->root_key.objectid,
-                                        &disk_key, 0, l->start, 0);
+                                        &disk_key, 0, l->start, 0, 0);
         if (IS_ERR(right))
                 return PTR_ERR(right);
 
@@ -3781,7 +3781,7 @@ static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
 
         root_sub_used(root, leaf->len);
 
-        btrfs_free_tree_block(trans, root, leaf, 0, 1);
+        btrfs_free_tree_block(trans, root, leaf, 0, 1, 0);
         return 0;
 }
 /*
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 3e4a07b79817..543f60bddb39 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2277,11 +2277,11 @@ struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
                                         struct btrfs_root *root, u32 blocksize,
                                         u64 parent, u64 root_objectid,
                                         struct btrfs_disk_key *key, int level,
-                                        u64 hint, u64 empty_size);
+                                        u64 hint, u64 empty_size, int for_cow);
 void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
                            struct btrfs_root *root,
                            struct extent_buffer *buf,
-                           u64 parent, int last_ref);
+                           u64 parent, int last_ref, int for_cow);
 struct extent_buffer *btrfs_init_new_buffer(struct btrfs_trans_handle *trans,
                                             struct btrfs_root *root,
                                             u64 bytenr, u32 blocksize,
@@ -2301,17 +2301,17 @@ int btrfs_reserve_extent(struct btrfs_trans_handle *trans,
                                   u64 search_end, struct btrfs_key *ins,
                                   u64 data);
 int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
-                  struct extent_buffer *buf, int full_backref);
+                  struct extent_buffer *buf, int full_backref, int for_cow);
 int btrfs_dec_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
-                  struct extent_buffer *buf, int full_backref);
+                  struct extent_buffer *buf, int full_backref, int for_cow);
 int btrfs_set_disk_extent_flags(struct btrfs_trans_handle *trans,
                                 struct btrfs_root *root,
                                 u64 bytenr, u64 num_bytes, u64 flags,
                                 int is_data);
 int btrfs_free_extent(struct btrfs_trans_handle *trans,
                       struct btrfs_root *root,
-                      u64 bytenr, u64 num_bytes, u64 parent,
-                      u64 root_objectid, u64 owner, u64 offset);
+                      u64 bytenr, u64 num_bytes, u64 parent, u64 root_objectid,
+                      u64 owner, u64 offset, int for_cow);
 
 int btrfs_free_reserved_extent(struct btrfs_root *root, u64 start, u64 len);
 int btrfs_free_and_pin_reserved_extent(struct btrfs_root *root,
@@ -2323,7 +2323,7 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
 int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
                          struct btrfs_root *root,
                          u64 bytenr, u64 num_bytes, u64 parent,
-                         u64 root_objectid, u64 owner, u64 offset);
+                         u64 root_objectid, u64 owner, u64 offset, int for_cow);
 
 int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
                                     struct btrfs_root *root);
@@ -2492,7 +2492,8 @@ static inline int btrfs_next_item(struct btrfs_root *root, struct btrfs_path *p)
 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path);
 int btrfs_leaf_free_space(struct btrfs_root *root, struct extent_buffer *leaf);
 void btrfs_drop_snapshot(struct btrfs_root *root,
-                         struct btrfs_block_rsv *block_rsv, int update_ref);
+                         struct btrfs_block_rsv *block_rsv, int update_ref,
+                         int for_reloc);
 int btrfs_drop_subtree(struct btrfs_trans_handle *trans,
                         struct btrfs_root *root,
                         struct extent_buffer *node,
diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
index 125cf76fcd08..3a0f0ab804f4 100644
--- a/fs/btrfs/delayed-ref.c
+++ b/fs/btrfs/delayed-ref.c
@@ -390,7 +390,8 @@ update_existing_head_ref(struct btrfs_delayed_ref_node *existing,
  * this does all the dirty work in terms of maintaining the correct
  * overall modification count.
  */
-static noinline int add_delayed_ref_head(struct btrfs_trans_handle *trans,
+static noinline int add_delayed_ref_head(struct btrfs_fs_info *fs_info,
+                                        struct btrfs_trans_handle *trans,
                                         struct btrfs_delayed_ref_node *ref,
                                         u64 bytenr, u64 num_bytes,
                                         int action, int is_data)
@@ -468,10 +469,12 @@ static noinline int add_delayed_ref_head(struct btrfs_trans_handle *trans,
 /*
  * helper to insert a delayed tree ref into the rbtree.
  */
-static noinline int add_delayed_tree_ref(struct btrfs_trans_handle *trans,
+static noinline int add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
+                                         struct btrfs_trans_handle *trans,
                                          struct btrfs_delayed_ref_node *ref,
                                          u64 bytenr, u64 num_bytes, u64 parent,
-                                         u64 ref_root, int level, int action)
+                                         u64 ref_root, int level, int action,
+                                         int for_cow)
 {
         struct btrfs_delayed_ref_node *existing;
         struct btrfs_delayed_tree_ref *full_ref;
@@ -522,11 +525,12 @@ static noinline int add_delayed_tree_ref(struct btrfs_trans_handle *trans,
 /*
  * helper to insert a delayed data ref into the rbtree.
  */
-static noinline int add_delayed_data_ref(struct btrfs_trans_handle *trans,
+static noinline int add_delayed_data_ref(struct btrfs_fs_info *fs_info,
+                                         struct btrfs_trans_handle *trans,
                                          struct btrfs_delayed_ref_node *ref,
                                          u64 bytenr, u64 num_bytes, u64 parent,
                                          u64 ref_root, u64 owner, u64 offset,
-                                         int action)
+                                         int action, int for_cow)
 {
         struct btrfs_delayed_ref_node *existing;
         struct btrfs_delayed_data_ref *full_ref;
@@ -554,6 +558,7 @@ static noinline int add_delayed_data_ref(struct btrfs_trans_handle *trans,
                 full_ref->root = ref_root;
                 ref->type = BTRFS_EXTENT_DATA_REF_KEY;
         }
+
         full_ref->objectid = owner;
         full_ref->offset = offset;
 
@@ -580,10 +585,12 @@ static noinline int add_delayed_data_ref(struct btrfs_trans_handle *trans,
  * to make sure the delayed ref is eventually processed before this
  * transaction commits.
  */
-int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
+int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
+                               struct btrfs_trans_handle *trans,
                                u64 bytenr, u64 num_bytes, u64 parent,
                                u64 ref_root,  int level, int action,
-                               struct btrfs_delayed_extent_op *extent_op)
+                               struct btrfs_delayed_extent_op *extent_op,
+                               int for_cow)
 {
         struct btrfs_delayed_tree_ref *ref;
         struct btrfs_delayed_ref_head *head_ref;
@@ -610,12 +617,13 @@ int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
          * insert both the head node and the new ref without dropping
          * the spin lock
          */
-        ret = add_delayed_ref_head(trans, &head_ref->node, bytenr, num_bytes,
-                                   action, 0);
+        ret = add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
+                                   num_bytes, action, 0);
         BUG_ON(ret);
 
-        ret = add_delayed_tree_ref(trans, &ref->node, bytenr, num_bytes,
-                                   parent, ref_root, level, action);
+        ret = add_delayed_tree_ref(fs_info, trans, &ref->node, bytenr,
+                                   num_bytes, parent, ref_root, level, action,
+                                   for_cow);
         BUG_ON(ret);
         spin_unlock(&delayed_refs->lock);
         return 0;
@@ -624,11 +632,13 @@ int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
 /*
  * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref.
  */
-int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
+int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
+                               struct btrfs_trans_handle *trans,
                                u64 bytenr, u64 num_bytes,
                                u64 parent, u64 ref_root,
                                u64 owner, u64 offset, int action,
-                               struct btrfs_delayed_extent_op *extent_op)
+                               struct btrfs_delayed_extent_op *extent_op,
+                               int for_cow)
 {
         struct btrfs_delayed_data_ref *ref;
         struct btrfs_delayed_ref_head *head_ref;
@@ -655,18 +665,20 @@ int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
          * insert both the head node and the new ref without dropping
          * the spin lock
          */
-        ret = add_delayed_ref_head(trans, &head_ref->node, bytenr, num_bytes,
-                                   action, 1);
+        ret = add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
+                                   num_bytes, action, 1);
         BUG_ON(ret);
 
-        ret = add_delayed_data_ref(trans, &ref->node, bytenr, num_bytes,
-                                   parent, ref_root, owner, offset, action);
+        ret = add_delayed_data_ref(fs_info, trans, &ref->node, bytenr,
+                                   num_bytes, parent, ref_root, owner, offset,
+                                   action, for_cow);
         BUG_ON(ret);
         spin_unlock(&delayed_refs->lock);
         return 0;
 }
 
-int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
+int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
+                                struct btrfs_trans_handle *trans,
                                 u64 bytenr, u64 num_bytes,
                                 struct btrfs_delayed_extent_op *extent_op)
 {
@@ -683,7 +695,7 @@ int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
         delayed_refs = &trans->transaction->delayed_refs;
         spin_lock(&delayed_refs->lock);
 
-        ret = add_delayed_ref_head(trans, &head_ref->node, bytenr,
+        ret = add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
                                    num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
                                    extent_op->is_data);
         BUG_ON(ret);
diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h
index e287e3b0eab0..8316bff18d30 100644
--- a/fs/btrfs/delayed-ref.h
+++ b/fs/btrfs/delayed-ref.h
@@ -151,16 +151,21 @@ static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
         }
 }
 
-int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
+int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
+                               struct btrfs_trans_handle *trans,
                                u64 bytenr, u64 num_bytes, u64 parent,
                                u64 ref_root, int level, int action,
-                               struct btrfs_delayed_extent_op *extent_op);
-int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
+                               struct btrfs_delayed_extent_op *extent_op,
+                               int for_cow);
+int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
+                               struct btrfs_trans_handle *trans,
                                u64 bytenr, u64 num_bytes,
                                u64 parent, u64 ref_root,
                                u64 owner, u64 offset, int action,
-                               struct btrfs_delayed_extent_op *extent_op);
-int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
+                               struct btrfs_delayed_extent_op *extent_op,
+                               int for_cow);
+int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
+                                struct btrfs_trans_handle *trans,
                                 u64 bytenr, u64 num_bytes,
                                 struct btrfs_delayed_extent_op *extent_op);
 
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 94abc25392f6..6f8cd17c9a9f 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1243,7 +1243,8 @@ static struct btrfs_root *alloc_log_tree(struct btrfs_trans_handle *trans,
         root->ref_cows = 0;
 
         leaf = btrfs_alloc_free_block(trans, root, root->leafsize, 0,
-                                      BTRFS_TREE_LOG_OBJECTID, NULL, 0, 0, 0);
+                                      BTRFS_TREE_LOG_OBJECTID, NULL,
+                                      0, 0, 0, 0);
         if (IS_ERR(leaf)) {
                 kfree(root);
                 return ERR_CAST(leaf);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 813c6bb96c9a..dc8b9a834596 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1872,20 +1872,24 @@ static int btrfs_discard_extent(struct btrfs_root *root, u64 bytenr,
 int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
                          struct btrfs_root *root,
                          u64 bytenr, u64 num_bytes, u64 parent,
-                         u64 root_objectid, u64 owner, u64 offset)
+                         u64 root_objectid, u64 owner, u64 offset, int for_cow)
 {
         int ret;
+        struct btrfs_fs_info *fs_info = root->fs_info;
+
         BUG_ON(owner < BTRFS_FIRST_FREE_OBJECTID &&
                root_objectid == BTRFS_TREE_LOG_OBJECTID);
 
         if (owner < BTRFS_FIRST_FREE_OBJECTID) {
-                ret = btrfs_add_delayed_tree_ref(trans, bytenr, num_bytes,
+                ret = btrfs_add_delayed_tree_ref(fs_info, trans, bytenr,
+                                        num_bytes,
                                         parent, root_objectid, (int)owner,
-                                        BTRFS_ADD_DELAYED_REF, NULL);
+                                        BTRFS_ADD_DELAYED_REF, NULL, for_cow);
         } else {
-                ret = btrfs_add_delayed_data_ref(trans, bytenr, num_bytes,
+                ret = btrfs_add_delayed_data_ref(fs_info, trans, bytenr,
+                                        num_bytes,
                                         parent, root_objectid, owner, offset,
-                                        BTRFS_ADD_DELAYED_REF, NULL);
+                                        BTRFS_ADD_DELAYED_REF, NULL, for_cow);
         }
         return ret;
 }
@@ -2405,7 +2409,8 @@ int btrfs_set_disk_extent_flags(struct btrfs_trans_handle *trans,
         extent_op->update_key = 0;
         extent_op->is_data = is_data ? 1 : 0;
 
-        ret = btrfs_add_delayed_extent_op(trans, bytenr, num_bytes, extent_op);
+        ret = btrfs_add_delayed_extent_op(root->fs_info, trans, bytenr,
+                                          num_bytes, extent_op);
         if (ret)
                 kfree(extent_op);
         return ret;
@@ -2590,7 +2595,7 @@ out:
 static int __btrfs_mod_ref(struct btrfs_trans_handle *trans,
                            struct btrfs_root *root,
                            struct extent_buffer *buf,
-                           int full_backref, int inc)
+                           int full_backref, int inc, int for_cow)
 {
         u64 bytenr;
         u64 num_bytes;
@@ -2603,7 +2608,7 @@ static int __btrfs_mod_ref(struct btrfs_trans_handle *trans,
         int level;
         int ret = 0;
         int (*process_func)(struct btrfs_trans_handle *, struct btrfs_root *,
-                            u64, u64, u64, u64, u64, u64);
+                            u64, u64, u64, u64, u64, u64, int);
 
         ref_root = btrfs_header_owner(buf);
         nritems = btrfs_header_nritems(buf);
@@ -2640,14 +2645,15 @@ static int __btrfs_mod_ref(struct btrfs_trans_handle *trans,
                         key.offset -= btrfs_file_extent_offset(buf, fi);
                         ret = process_func(trans, root, bytenr, num_bytes,
                                            parent, ref_root, key.objectid,
-                                           key.offset);
+                                           key.offset, for_cow);
                         if (ret)
                                 goto fail;
                 } else {
                         bytenr = btrfs_node_blockptr(buf, i);
                         num_bytes = btrfs_level_size(root, level - 1);
                         ret = process_func(trans, root, bytenr, num_bytes,
-                                           parent, ref_root, level - 1, 0);
+                                           parent, ref_root, level - 1, 0,
+                                           for_cow);
                         if (ret)
                                 goto fail;
                 }
@@ -2659,15 +2665,15 @@ fail:
 }
 
 int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
-                  struct extent_buffer *buf, int full_backref)
+                  struct extent_buffer *buf, int full_backref, int for_cow)
 {
-        return __btrfs_mod_ref(trans, root, buf, full_backref, 1);
+        return __btrfs_mod_ref(trans, root, buf, full_backref, 1, for_cow);
 }
 
 int btrfs_dec_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
-                  struct extent_buffer *buf, int full_backref)
+                  struct extent_buffer *buf, int full_backref, int for_cow)
 {
-        return __btrfs_mod_ref(trans, root, buf, full_backref, 0);
+        return __btrfs_mod_ref(trans, root, buf, full_backref, 0, for_cow);
 }
 
 static int write_one_cache_group(struct btrfs_trans_handle *trans,
@@ -4937,16 +4943,17 @@ out:
 void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
                            struct btrfs_root *root,
                            struct extent_buffer *buf,
-                           u64 parent, int last_ref)
+                           u64 parent, int last_ref, int for_cow)
 {
         struct btrfs_block_group_cache *cache = NULL;
         int ret;
 
         if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID) {
-                ret = btrfs_add_delayed_tree_ref(trans, buf->start, buf->len,
-                                                parent, root->root_key.objectid,
-                                                btrfs_header_level(buf),
-                                                BTRFS_DROP_DELAYED_REF, NULL);
+                ret = btrfs_add_delayed_tree_ref(root->fs_info, trans,
+                                        buf->start, buf->len,
+                                        parent, root->root_key.objectid,
+                                        btrfs_header_level(buf),
+                                        BTRFS_DROP_DELAYED_REF, NULL, for_cow);
                 BUG_ON(ret);
         }
 
@@ -4981,12 +4988,12 @@ out:
         btrfs_put_block_group(cache);
 }
 
-int btrfs_free_extent(struct btrfs_trans_handle *trans,
-                      struct btrfs_root *root,
-                      u64 bytenr, u64 num_bytes, u64 parent,
-                      u64 root_objectid, u64 owner, u64 offset)
+int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+                      u64 bytenr, u64 num_bytes, u64 parent, u64 root_objectid,
+                      u64 owner, u64 offset, int for_cow)
 {
         int ret;
+        struct btrfs_fs_info *fs_info = root->fs_info;
 
         /*
          * tree log blocks never actually go into the extent allocation
@@ -4998,14 +5005,17 @@ int btrfs_free_extent(struct btrfs_trans_handle *trans,
                 btrfs_pin_extent(root, bytenr, num_bytes, 1);
                 ret = 0;
         } else if (owner < BTRFS_FIRST_FREE_OBJECTID) {
-                ret = btrfs_add_delayed_tree_ref(trans, bytenr, num_bytes,
+                ret = btrfs_add_delayed_tree_ref(fs_info, trans, bytenr,
+                                        num_bytes,
                                         parent, root_objectid, (int)owner,
-                                        BTRFS_DROP_DELAYED_REF, NULL);
+                                        BTRFS_DROP_DELAYED_REF, NULL, for_cow);
                 BUG_ON(ret);
         } else {
-                ret = btrfs_add_delayed_data_ref(trans, bytenr, num_bytes,
-                                        parent, root_objectid, owner,
-                                        offset, BTRFS_DROP_DELAYED_REF, NULL);
+                ret = btrfs_add_delayed_data_ref(fs_info, trans, bytenr,
+                                                num_bytes,
+                                                parent, root_objectid, owner,
+                                                offset, BTRFS_DROP_DELAYED_REF,
+                                                NULL, for_cow);
                 BUG_ON(ret);
         }
         return ret;
@@ -5826,9 +5836,10 @@ int btrfs_alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
 
         BUG_ON(root_objectid == BTRFS_TREE_LOG_OBJECTID);
 
-        ret = btrfs_add_delayed_data_ref(trans, ins->objectid, ins->offset,
-                                         0, root_objectid, owner, offset,
-                                         BTRFS_ADD_DELAYED_EXTENT, NULL);
+        ret = btrfs_add_delayed_data_ref(root->fs_info, trans, ins->objectid,
+                                         ins->offset, 0,
+                                         root_objectid, owner, offset,
+                                         BTRFS_ADD_DELAYED_EXTENT, NULL, 0);
         return ret;
 }
 
@@ -5998,7 +6009,7 @@ struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
                                         struct btrfs_root *root, u32 blocksize,
                                         u64 parent, u64 root_objectid,
                                         struct btrfs_disk_key *key, int level,
-                                        u64 hint, u64 empty_size)
+                                        u64 hint, u64 empty_size, int for_cow)
 {
         struct btrfs_key ins;
         struct btrfs_block_rsv *block_rsv;
@@ -6042,10 +6053,11 @@ struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
                 extent_op->update_flags = 1;
                 extent_op->is_data = 0;
 
-                ret = btrfs_add_delayed_tree_ref(trans, ins.objectid,
+                ret = btrfs_add_delayed_tree_ref(root->fs_info, trans,
+                                        ins.objectid,
                                         ins.offset, parent, root_objectid,
                                         level, BTRFS_ADD_DELAYED_EXTENT,
-                                        extent_op);
+                                        extent_op, for_cow);
                 BUG_ON(ret);
         }
         return buf;
@@ -6062,6 +6074,7 @@ struct walk_control {
         int keep_locks;
         int reada_slot;
         int reada_count;
+        int for_reloc;
 };
 
 #define DROP_REFERENCE  1
@@ -6200,9 +6213,9 @@ static noinline int walk_down_proc(struct btrfs_trans_handle *trans,
         /* wc->stage == UPDATE_BACKREF */
         if (!(wc->flags[level] & flag)) {
                 BUG_ON(!path->locks[level]);
-                ret = btrfs_inc_ref(trans, root, eb, 1);
+                ret = btrfs_inc_ref(trans, root, eb, 1, wc->for_reloc);
                 BUG_ON(ret);
-                ret = btrfs_dec_ref(trans, root, eb, 0);
+                ret = btrfs_dec_ref(trans, root, eb, 0, wc->for_reloc);
                 BUG_ON(ret);
                 ret = btrfs_set_disk_extent_flags(trans, root, eb->start,
                                                   eb->len, flag, 0);
@@ -6346,7 +6359,7 @@ skip:
                 }
 
                 ret = btrfs_free_extent(trans, root, bytenr, blocksize, parent,
-                                        root->root_key.objectid, level - 1, 0);
+                                root->root_key.objectid, level - 1, 0, 0);
                 BUG_ON(ret);
         }
         btrfs_tree_unlock(next);
@@ -6420,9 +6433,11 @@ static noinline int walk_up_proc(struct btrfs_trans_handle *trans,
         if (wc->refs[level] == 1) {
                 if (level == 0) {
                         if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF)
-                                ret = btrfs_dec_ref(trans, root, eb, 1);
+                                ret = btrfs_dec_ref(trans, root, eb, 1,
+                                                    wc->for_reloc);
                         else
-                                ret = btrfs_dec_ref(trans, root, eb, 0);
+                                ret = btrfs_dec_ref(trans, root, eb, 0,
+                                                    wc->for_reloc);
                         BUG_ON(ret);
                 }
                 /* make block locked assertion in clean_tree_block happy */
@@ -6449,7 +6464,7 @@ static noinline int walk_up_proc(struct btrfs_trans_handle *trans,
                                btrfs_header_owner(path->nodes[level + 1]));
         }
 
-        btrfs_free_tree_block(trans, root, eb, parent, wc->refs[level] == 1);
+        btrfs_free_tree_block(trans, root, eb, parent, wc->refs[level] == 1, 0);
 out:
         wc->refs[level] = 0;
         wc->flags[level] = 0;
@@ -6533,7 +6548,8 @@ static noinline int walk_up_tree(struct btrfs_trans_handle *trans,
  * blocks are properly updated.
  */
 void btrfs_drop_snapshot(struct btrfs_root *root,
-                         struct btrfs_block_rsv *block_rsv, int update_ref)
+                         struct btrfs_block_rsv *block_rsv, int update_ref,
+                         int for_reloc)
 {
         struct btrfs_path *path;
         struct btrfs_trans_handle *trans;
@@ -6621,6 +6637,7 @@ void btrfs_drop_snapshot(struct btrfs_root *root,
         wc->stage = DROP_REFERENCE;
         wc->update_ref = update_ref;
         wc->keep_locks = 0;
+        wc->for_reloc = for_reloc;
         wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(root);
 
         while (1) {
@@ -6705,6 +6722,7 @@ out:
  * drop subtree rooted at tree block 'node'.
  *
  * NOTE: this function will unlock and release tree block 'node'
+ * only used by relocation code
  */
 int btrfs_drop_subtree(struct btrfs_trans_handle *trans,
                         struct btrfs_root *root,
@@ -6749,6 +6767,7 @@ int btrfs_drop_subtree(struct btrfs_trans_handle *trans,
         wc->stage = DROP_REFERENCE;
         wc->update_ref = 0;
         wc->keep_locks = 1;
+        wc->for_reloc = 1;
         wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(root);
 
         while (1) {
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index f2e928289600..d2b60ed6c33f 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -678,7 +678,7 @@ next_slot:
                                                 disk_bytenr, num_bytes, 0,
                                                 root->root_key.objectid,
                                                 new_key.objectid,
-                                                start - extent_offset);
+                                                start - extent_offset, 0);
                                 BUG_ON(ret);
                                 *hint_byte = disk_bytenr;
                         }
@@ -753,7 +753,7 @@ next_slot:
                                                 disk_bytenr, num_bytes, 0,
                                                 root->root_key.objectid,
                                                 key.objectid, key.offset -
-                                                extent_offset);
+                                                extent_offset, 0);
                                 BUG_ON(ret);
                                 inode_sub_bytes(inode,
                                                 extent_end - key.offset);
@@ -962,7 +962,7 @@ again:
 
                 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
                                            root->root_key.objectid,
-                                           ino, orig_offset);
+                                           ino, orig_offset, 0);
                 BUG_ON(ret);
 
                 if (split == start) {
@@ -989,7 +989,7 @@ again:
                 del_nr++;
                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
                                         0, root->root_key.objectid,
-                                        ino, orig_offset);
+                                        ino, orig_offset, 0);
                 BUG_ON(ret);
         }
         other_start = 0;
@@ -1006,7 +1006,7 @@ again:
                 del_nr++;
                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
                                         0, root->root_key.objectid,
-                                        ino, orig_offset);
+                                        ino, orig_offset, 0);
                 BUG_ON(ret);
         }
         if (del_nr == 0) {
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index c5ccec23984c..ea819386b864 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3139,7 +3139,7 @@ delete:
                         ret = btrfs_free_extent(trans, root, extent_start,
                                                 extent_num_bytes, 0,
                                                 btrfs_header_owner(leaf),
-                                                ino, extent_offset);
+                                                ino, extent_offset, 0);
                         BUG_ON(ret);
                 }
 
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 72d461656f60..c48f2e931ea0 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -358,7 +358,7 @@ static noinline int create_subvol(struct btrfs_root *root,
                 return PTR_ERR(trans);
 
         leaf = btrfs_alloc_free_block(trans, root, root->leafsize,
-                                      0, objectid, NULL, 0, 0, 0);
+                                      0, objectid, NULL, 0, 0, 0, 0);
         if (IS_ERR(leaf)) {
                 ret = PTR_ERR(leaf);
                 goto fail;
@@ -2425,7 +2425,8 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
                                                         disko, diskl, 0,
                                                         root->root_key.objectid,
                                                         btrfs_ino(inode),
-                                                        new_key.offset - datao);
+                                                        new_key.offset - datao,
+                                                        0);
                                         BUG_ON(ret);
                                 }
                         } else if (type == BTRFS_FILE_EXTENT_INLINE) {
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index dff29d5e151a..8c1aae2c845d 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -1604,12 +1604,12 @@ int replace_file_extents(struct btrfs_trans_handle *trans,
                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
                                            num_bytes, parent,
                                            btrfs_header_owner(leaf),
-                                           key.objectid, key.offset);
+                                           key.objectid, key.offset, 1);
                 BUG_ON(ret);
 
                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
                                         parent, btrfs_header_owner(leaf),
-                                        key.objectid, key.offset);
+                                        key.objectid, key.offset, 1);
                 BUG_ON(ret);
         }
         if (dirty)
@@ -1778,21 +1778,23 @@ again:
 
                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
                                         path->nodes[level]->start,
-                                        src->root_key.objectid, level - 1, 0);
+                                        src->root_key.objectid, level - 1, 0,
+                                        1);
                 BUG_ON(ret);
                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
                                         0, dest->root_key.objectid, level - 1,
-                                        0);
+                                        0, 1);
                 BUG_ON(ret);
 
                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
                                         path->nodes[level]->start,
-                                        src->root_key.objectid, level - 1, 0);
+                                        src->root_key.objectid, level - 1, 0,
+                                        1);
                 BUG_ON(ret);
 
                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
                                         0, dest->root_key.objectid, level - 1,
-                                        0);
+                                        0, 1);
                 BUG_ON(ret);
 
                 btrfs_unlock_up_safe(path, 0);
@@ -2244,7 +2246,7 @@ again:
                 } else {
                         list_del_init(&reloc_root->root_list);
                 }
-                btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0);
+                btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
         }
 
         if (found) {
@@ -2558,7 +2560,7 @@ static int do_relocation(struct btrfs_trans_handle *trans,
                                                 node->eb->start, blocksize,
                                                 upper->eb->start,
                                                 btrfs_header_owner(upper->eb),
-                                                node->level, 0);
+                                                node->level, 0, 1);
                         BUG_ON(ret);
 
                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 81376d94cd3c..a2bfedcbcabc 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1393,9 +1393,9 @@ int btrfs_clean_old_snapshots(struct btrfs_root *root)
 
                 if (btrfs_header_backref_rev(root->node) <
                     BTRFS_MIXED_BACKREF_REV)
-                        btrfs_drop_snapshot(root, NULL, 0);
+                        btrfs_drop_snapshot(root, NULL, 0, 0);
                 else
-                        btrfs_drop_snapshot(root, NULL, 1);
+                        btrfs_drop_snapshot(root, NULL, 1, 0);
         }
         return 0;
 }
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index f4d81c06d48f..fce7b9ec3bfa 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -589,7 +589,7 @@ static noinline int replay_one_extent(struct btrfs_trans_handle *trans,
                                 ret = btrfs_inc_extent_ref(trans, root,
                                                 ins.objectid, ins.offset,
                                                 0, root->root_key.objectid,
-                                                key->objectid, offset);
+                                                key->objectid, offset, 0);
                                 BUG_ON(ret);
                         } else {
                                 /*