Btrfs: Online btree defragmentation fixes

The btree defragger wasn't making forward progress because the new key wasn't
being saved by the btrfs_search_forward function.

This also disables the automatic btree defrag, it wasn't scaling well to
huge filesystems.  The auto-defrag needs to be done differently.

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

1 files changed, 19 insertions, 17 deletions

diff --git a/fs/btrfs/tree-defrag.c b/fs/btrfs/tree-defrag.c
index b17693f61fbc..cc2650b06952 100644
--- a/fs/btrfs/tree-defrag.c
+++ b/fs/btrfs/tree-defrag.c
@@ -32,10 +32,13 @@ int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
         int wret;
         int level;
         int orig_level;
-        int i;
         int is_extent = 0;
         int next_key_ret = 0;
         u64 last_ret = 0;
+        u64 min_trans = 0;
+
+        if (cache_only)
+                goto out;
 
         if (root->fs_info->extent_root == root) {
                 /*
@@ -43,10 +46,6 @@ int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
                  * we can't defrag the extent root without deadlock
                  */
                 goto out;
-#if 0
-                mutex_lock(&root->fs_info->alloc_mutex);
-                is_extent = 1;
-#endif
         }
 
         if (root->ref_cows == 0 && !is_extent)
@@ -84,6 +83,17 @@ int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
 
         path->lowest_level = 1;
         path->keep_locks = 1;
+        if (cache_only)
+                min_trans = root->defrag_trans_start;
+
+        ret = btrfs_search_forward(root, &key, path, cache_only, min_trans);
+        if (ret < 0)
+                goto out;
+        if (ret > 0) {
+                ret = 0;
+                goto out;
+        }
+        btrfs_release_path(root, path);
         wret = btrfs_search_slot(trans, root, &key, path, 0, 1);
 
         if (wret < 0) {
@@ -95,7 +105,8 @@ int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
                 goto out;
         }
         path->slots[1] = btrfs_header_nritems(path->nodes[1]);
-        next_key_ret = btrfs_find_next_key(root, path, &key, 1);
+        next_key_ret = btrfs_find_next_key(root, path, &key, 1, cache_only,
+                                           min_trans);
         ret = btrfs_realloc_node(trans, root,
                                  path->nodes[1], 0,
                                  cache_only, &last_ret,
@@ -106,19 +117,9 @@ int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
                 ret = -EAGAIN;
         }
 
-        for (i = 1; i < BTRFS_MAX_LEVEL; i++) {
-                if (path->locks[i]) {
-                        btrfs_tree_unlock(path->nodes[i]);
-                        path->locks[i] = 0;
-                }
-                if (path->nodes[i]) {
-                        free_extent_buffer(path->nodes[i]);
-                        path->nodes[i] = NULL;
-                }
-        }
+        btrfs_release_path(root, path);
         if (is_extent)
                 btrfs_extent_post_op(trans, root);
-
 out:
         if (is_extent)
                 mutex_unlock(&root->fs_info->alloc_mutex);
@@ -138,6 +139,7 @@ done:
         if (ret != -EAGAIN) {
                 memset(&root->defrag_progress, 0,
                        sizeof(root->defrag_progress));
+                root->defrag_trans_start = trans->transid;
         }
         return ret;
 }