Btrfs: make delayed ref lock logic more readable

Locking and unlocking delayed ref mutex are in the different functions,
and the name of lock functions is not uniform, so the readability is not
so good, this patch optimizes the lock logic and makes it more readable.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
index 455894f1ca3bdba5a6fa8904def71387482d39fa..b7a0641ead7729bd25b21ad3f0d1a44b76799172 100644 (file)
--- a/fs/btrfs/delayed-ref.c
+++ b/fs/btrfs/delayed-ref.c
@@ -426,6 +426,14 @@ int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
        return 1;
 }
 
+void btrfs_release_ref_cluster(struct list_head *cluster)
+{
+       struct list_head *pos, *q;
+
+       list_for_each_safe(pos, q, cluster)
+               list_del_init(pos);
+}
+
 /*
  * helper function to update an extent delayed ref in the
  * rbtree.  existing and update must both have the same

diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h
index fe50392cdf768bf990928522a6e81f56af75d160..7939149f8f274c96813f7097a7825af018aec154 100644 (file)
--- a/fs/btrfs/delayed-ref.h
+++ b/fs/btrfs/delayed-ref.h
@@ -211,8 +211,14 @@ struct btrfs_delayed_ref_head *
 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
                           struct btrfs_delayed_ref_head *head);
+static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
+{
+       mutex_unlock(&head->mutex);
+}
+
 int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
                           struct list_head *cluster, u64 search_start);
+void btrfs_release_ref_cluster(struct list_head *cluster);
 
 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
                            struct btrfs_delayed_ref_root *delayed_refs,

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 9bd87f0d73d0535dd31e9e931cf9fd2e8f574423..b4cb8186035f55eb9de3201e3c89d8eac2226290 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2143,7 +2143,6 @@ static int run_one_delayed_ref(struct btrfs_trans_handle *trans,
                                                      node->num_bytes);
                        }
                }
-               mutex_unlock(&head->mutex);
                return ret;
        }
 
@@ -2258,7 +2257,7 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans,
                         * process of being added. Don't run this ref yet.
                         */
                        list_del_init(&locked_ref->cluster);
-                       mutex_unlock(&locked_ref->mutex);
+                       btrfs_delayed_ref_unlock(locked_ref);
                        locked_ref = NULL;
                        delayed_refs->num_heads_ready++;
                        spin_unlock(&delayed_refs->lock);
@@ -2297,25 +2296,22 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans,
                                btrfs_free_delayed_extent_op(extent_op);
 
                                if (ret) {
-                                       list_del_init(&locked_ref->cluster);
-                                       mutex_unlock(&locked_ref->mutex);
-
-                                       printk(KERN_DEBUG "btrfs: run_delayed_extent_op returned %d\n", ret);
+                                       printk(KERN_DEBUG
+                                              "btrfs: run_delayed_extent_op "
+                                              "returned %d\n", ret);
                                        spin_lock(&delayed_refs->lock);
+                                       btrfs_delayed_ref_unlock(locked_ref);
                                        return ret;
                                }
 
                                goto next;
                        }
-
-                       list_del_init(&locked_ref->cluster);
-                       locked_ref = NULL;
                }
 
                ref->in_tree = 0;
                rb_erase(&ref->rb_node, &delayed_refs->root);
                delayed_refs->num_entries--;
-               if (locked_ref) {
+               if (!btrfs_delayed_ref_is_head(ref)) {
                        /*
                         * when we play the delayed ref, also correct the
                         * ref_mod on head
@@ -2337,20 +2333,29 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans,
                ret = run_one_delayed_ref(trans, root, ref, extent_op,
                                          must_insert_reserved);
 
-               btrfs_put_delayed_ref(ref);
                btrfs_free_delayed_extent_op(extent_op);
-               count++;
-
                if (ret) {
-                       if (locked_ref) {
-                               list_del_init(&locked_ref->cluster);
-                               mutex_unlock(&locked_ref->mutex);
-                       }
-                       printk(KERN_DEBUG "btrfs: run_one_delayed_ref returned %d\n", ret);
+                       btrfs_delayed_ref_unlock(locked_ref);
+                       btrfs_put_delayed_ref(ref);
+                       printk(KERN_DEBUG
+                              "btrfs: run_one_delayed_ref returned %d\n", ret);
                        spin_lock(&delayed_refs->lock);
                        return ret;
                }
 
+               /*
+                * If this node is a head, that means all the refs in this head
+                * have been dealt with, and we will pick the next head to deal
+                * with, so we must unlock the head and drop it from the cluster
+                * list before we release it.
+                */
+               if (btrfs_delayed_ref_is_head(ref)) {
+                       list_del_init(&locked_ref->cluster);
+                       btrfs_delayed_ref_unlock(locked_ref);
+                       locked_ref = NULL;
+               }
+               btrfs_put_delayed_ref(ref);
+               count++;
 next:
                cond_resched();
                spin_lock(&delayed_refs->lock);
@@ -2500,6 +2505,7 @@ int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
 
                ret = run_clustered_refs(trans, root, &cluster);
                if (ret < 0) {
+                       btrfs_release_ref_cluster(&cluster);
                        spin_unlock(&delayed_refs->lock);
                        btrfs_abort_transaction(trans, root, ret);
                        return ret;