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, 12 insertions, 9 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 6e1d36702ff7..94ce79f76e5f 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2217,6 +2217,7 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans,
         struct btrfs_delayed_ref_node *ref;
         struct btrfs_delayed_ref_head *locked_ref = NULL;
         struct btrfs_delayed_extent_op *extent_op;
+        struct btrfs_fs_info *fs_info = root->fs_info;
         int ret;
         int count = 0;
         int must_insert_reserved = 0;
@@ -2255,7 +2256,7 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans,
                 ref = select_delayed_ref(locked_ref);
 
                 if (ref && ref->seq &&
-                    btrfs_check_delayed_seq(delayed_refs, ref->seq)) {
+                    btrfs_check_delayed_seq(fs_info, delayed_refs, ref->seq)) {
                         /*
                          * there are still refs with lower seq numbers in the
                          * process of being added. Don't run this ref yet.
@@ -2337,7 +2338,7 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans,
                 }
 
 next:
-                do_chunk_alloc(trans, root->fs_info->extent_root,
+                do_chunk_alloc(trans, fs_info->extent_root,
                                2 * 1024 * 1024,
                                btrfs_get_alloc_profile(root, 0),
                                CHUNK_ALLOC_NO_FORCE);
@@ -2347,18 +2348,19 @@ next:
         return count;
 }
 
-static void wait_for_more_refs(struct btrfs_delayed_ref_root *delayed_refs,
+static void wait_for_more_refs(struct btrfs_fs_info *fs_info,
+                               struct btrfs_delayed_ref_root *delayed_refs,
                                unsigned long num_refs,
                                struct list_head *first_seq)
 {
         spin_unlock(&delayed_refs->lock);
         pr_debug("waiting for more refs (num %ld, first %p)\n",
                  num_refs, first_seq);
-        wait_event(delayed_refs->seq_wait,
+        wait_event(fs_info->tree_mod_seq_wait,
                    num_refs != delayed_refs->num_entries ||
-                   delayed_refs->seq_head.next != first_seq);
+                   fs_info->tree_mod_seq_list.next != first_seq);
         pr_debug("done waiting for more refs (num %ld, first %p)\n",
-                 delayed_refs->num_entries, delayed_refs->seq_head.next);
+                 delayed_refs->num_entries, fs_info->tree_mod_seq_list.next);
         spin_lock(&delayed_refs->lock);
 }
 
@@ -2403,6 +2405,7 @@ int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
 again:
         consider_waiting = 0;
         spin_lock(&delayed_refs->lock);
+
         if (count == 0) {
                 count = delayed_refs->num_entries * 2;
                 run_most = 1;
@@ -2437,7 +2440,7 @@ again:
                                 num_refs = delayed_refs->num_entries;
                                 first_seq = root->fs_info->tree_mod_seq_list.next;
                         } else {
-                                wait_for_more_refs(delayed_refs,
+                                wait_for_more_refs(root->fs_info, delayed_refs,
                                                    num_refs, first_seq);
                                 /*
                                  * after waiting, things have changed. we
@@ -5190,8 +5193,8 @@ static noinline int check_ref_cleanup(struct btrfs_trans_handle *trans,
         rb_erase(&head->node.rb_node, &delayed_refs->root);
 
         delayed_refs->num_entries--;
-        if (waitqueue_active(&delayed_refs->seq_wait))
-                wake_up(&delayed_refs->seq_wait);
+        if (waitqueue_active(&root->fs_info->tree_mod_seq_wait))
+                wake_up(&root->fs_info->tree_mod_seq_wait);
 
         /*
          * we don't take a ref on the node because we're removing it from the