Btrfs: Further reduce the concurrency penalty of defrag and drop_snapshot

Signed-off-by: Chris Mason <chris.mason@oracle.com>

3 files changed, 11 insertions, 12 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index ba50bd7b9a78..120c448f58f8 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1312,7 +1312,10 @@ static void reada_walk_down(struct btrfs_root *root,
                 BUG_ON(ret);
                 if (refs != 1)
                         continue;
+                mutex_unlock(&root->fs_info->fs_mutex);
                 ret = readahead_tree_block(root, blocknr);
+                cond_resched();
+                mutex_lock(&root->fs_info->fs_mutex);
                 if (ret)
                         break;
         }
@@ -1445,7 +1448,6 @@ int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
         struct btrfs_path *path;
         int i;
         int orig_level;
-        int num_walks = 0;
         struct btrfs_root_item *root_item = &root->root_item;
 
         path = btrfs_alloc_path();
@@ -1486,12 +1488,9 @@ int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
                         break;
                 if (wret < 0)
                         ret = wret;
-                num_walks++;
-                if (num_walks > 2) {
-                        ret = -EAGAIN;
-                        get_bh(root->node);
-                        break;
-                }
+                ret = -EAGAIN;
+                get_bh(root->node);
+                break;
         }
         for (i = 0; i <= orig_level; i++) {
                 if (path->nodes[i]) {
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index e64ecec3f52e..204337c5ca0f 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -364,6 +364,9 @@ int btrfs_defrag_dirty_roots(struct btrfs_fs_info *info)
                                         break;
                         }
                         root->defrag_running = 0;
+                        radix_tree_tag_clear(&info->fs_roots_radix,
+                                     (unsigned long)root->root_key.objectid,
+                                     BTRFS_ROOT_DEFRAG_TAG);
                 }
         }
         btrfs_end_transaction(trans, tree_root);
diff --git a/fs/btrfs/tree-defrag.c b/fs/btrfs/tree-defrag.c
index 15d0a486fb59..7ea66b4aa5c2 100644
--- a/fs/btrfs/tree-defrag.c
+++ b/fs/btrfs/tree-defrag.c
@@ -148,7 +148,6 @@ int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
         int level;
         int orig_level;
         int i;
-        int num_runs = 0;
 
         if (root->ref_cows == 0) {
                 goto out;
@@ -200,10 +199,8 @@ int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
                         break;
                 if (wret < 0)
                         ret = wret;
-                if (num_runs++ > 8) {
-                        ret = -EAGAIN;
-                        break;
-                }
+                ret = -EAGAIN;
+                break;
         }
         for (i = 0; i <= orig_level; i++) {
                 if (path->nodes[i]) {