Btrfs: join tree mod log code with the code holding back delayed refs

We've got two mechanisms both required for reliable backref resolving (tree
mod log and holding back delayed refs). You cannot make use of one without
the other. So instead of requiring the user of this mechanism to setup both
correctly, we join them into a single interface.

Additionally, we stop inserting non-blockers into fs_info->tree_mod_seq_list
as we did before, which was of no value.

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

1 files changed, 24 insertions, 20 deletions

diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
index 13ae7b04790e..21a757717637 100644
--- a/fs/btrfs/delayed-ref.c
+++ b/fs/btrfs/delayed-ref.c
@@ -233,22 +233,26 @@ int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
         return 0;
 }
 
-int btrfs_check_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs,
+int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
+                            struct btrfs_delayed_ref_root *delayed_refs,
                             u64 seq)
 {
         struct seq_list *elem;
-
-        assert_spin_locked(&delayed_refs->lock);
-        if (list_empty(&delayed_refs->seq_head))
-                return 0;
-
-        elem = list_first_entry(&delayed_refs->seq_head, struct seq_list, list);
-        if (seq >= elem->seq) {
-                pr_debug("holding back delayed_ref %llu, lowest is %llu (%p)\n",
-                         seq, elem->seq, delayed_refs);
-                return 1;
+        int ret = 0;
+
+        spin_lock(&fs_info->tree_mod_seq_lock);
+        if (!list_empty(&fs_info->tree_mod_seq_list)) {
+                elem = list_first_entry(&fs_info->tree_mod_seq_list,
+                                        struct seq_list, list);
+                if (seq >= elem->seq) {
+                        pr_debug("holding back delayed_ref %llu, lowest is "
+                                 "%llu (%p)\n", seq, elem->seq, delayed_refs);
+                        ret = 1;
+                }
         }
-        return 0;
+
+        spin_unlock(&fs_info->tree_mod_seq_lock);
+        return ret;
 }
 
 int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
@@ -526,7 +530,7 @@ static noinline void add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
         ref->in_tree = 1;
 
         if (is_fstree(ref_root))
-                seq = inc_delayed_seq(delayed_refs);
+                seq = btrfs_inc_tree_mod_seq(fs_info);
         ref->seq = seq;
 
         full_ref = btrfs_delayed_node_to_tree_ref(ref);
@@ -585,7 +589,7 @@ static noinline void add_delayed_data_ref(struct btrfs_fs_info *fs_info,
         ref->in_tree = 1;
 
         if (is_fstree(ref_root))
-                seq = inc_delayed_seq(delayed_refs);
+                seq = btrfs_inc_tree_mod_seq(fs_info);
         ref->seq = seq;
 
         full_ref = btrfs_delayed_node_to_data_ref(ref);
@@ -659,8 +663,8 @@ int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
                                    num_bytes, parent, ref_root, level, action,
                                    for_cow);
         if (!is_fstree(ref_root) &&
-            waitqueue_active(&delayed_refs->seq_wait))
-                wake_up(&delayed_refs->seq_wait);
+            waitqueue_active(&fs_info->tree_mod_seq_wait))
+                wake_up(&fs_info->tree_mod_seq_wait);
         spin_unlock(&delayed_refs->lock);
 
         return 0;
@@ -708,8 +712,8 @@ int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
                                    num_bytes, parent, ref_root, owner, offset,
                                    action, for_cow);
         if (!is_fstree(ref_root) &&
-            waitqueue_active(&delayed_refs->seq_wait))
-                wake_up(&delayed_refs->seq_wait);
+            waitqueue_active(&fs_info->tree_mod_seq_wait))
+                wake_up(&fs_info->tree_mod_seq_wait);
         spin_unlock(&delayed_refs->lock);
 
         return 0;
@@ -736,8 +740,8 @@ int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
                                    num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
                                    extent_op->is_data);
 
-        if (waitqueue_active(&delayed_refs->seq_wait))
-                wake_up(&delayed_refs->seq_wait);
+        if (waitqueue_active(&fs_info->tree_mod_seq_wait))
+                wake_up(&fs_info->tree_mod_seq_wait);
         spin_unlock(&delayed_refs->lock);
         return 0;
 }