Btrfs: put all block modifications into the tree mod log

When running functions that can make changes to the internal trees
(e.g. btrfs_search_slot), we check if somebody may be interested in the
block we're currently modifying. If so, we record our modification to be
able to rewind it later on.

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

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 72b9f97e2fdcff590d3ec96b86752a9874ebb620..07c1a96aa4a83ebf43c55247dfe2514c6766c53e 100644 (file)
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -39,6 +39,14 @@ static int balance_node_right(struct btrfs_trans_handle *trans,
                              struct extent_buffer *src_buf);
 static void del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                   struct btrfs_path *path, int level, int slot);
+static void tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
+                                struct extent_buffer *eb);
+struct extent_buffer *read_old_tree_block(struct btrfs_root *root, u64 bytenr,
+                                         u32 blocksize, u64 parent_transid,
+                                         u64 time_seq);
+struct extent_buffer *btrfs_find_old_tree_block(struct btrfs_root *root,
+                                               u64 bytenr, u32 blocksize,
+                                               u64 time_seq);
 
 struct btrfs_path *btrfs_alloc_path(void)
 {
@@ -816,6 +824,12 @@ static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
                        ret = btrfs_dec_ref(trans, root, buf, 1, 1);
                        BUG_ON(ret); /* -ENOMEM */
                }
+               /*
+                * don't log freeing in case we're freeing the root node, this
+                * is done by tree_mod_log_set_root_pointer later
+                */
+               if (buf != root->node && btrfs_header_level(buf) != 0)
+                       tree_mod_log_free_eb(root->fs_info, buf);
                clean_tree_block(trans, root, buf);
                *last_ref = 1;
        }
@@ -913,6 +927,7 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
                        parent_start = 0;
 
                extent_buffer_get(cow);
+               tree_mod_log_set_root_pointer(root, cow);
                rcu_assign_pointer(root->node, cow);
 
                btrfs_free_tree_block(trans, root, buf, parent_start,
@@ -926,6 +941,8 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
                        parent_start = 0;
 
                WARN_ON(trans->transid != btrfs_header_generation(parent));
+               tree_mod_log_insert_key(root->fs_info, parent, parent_slot,
+                                       MOD_LOG_KEY_REPLACE);
                btrfs_set_node_blockptr(parent, parent_slot,
                                        cow->start);
                btrfs_set_node_ptr_generation(parent, parent_slot,
@@ -1381,6 +1398,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
                        goto enospc;
                }
 
+               tree_mod_log_set_root_pointer(root, child);
                rcu_assign_pointer(root->node, child);
 
                add_root_to_dirty_list(root);
@@ -1455,6 +1473,8 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
                } else {
                        struct btrfs_disk_key right_key;
                        btrfs_node_key(right, &right_key, 0);
+                       tree_mod_log_set_node_key(root->fs_info, parent,
+                                                 &right_key, pslot + 1, 0);
                        btrfs_set_node_key(parent, &right_key, pslot + 1);
                        btrfs_mark_buffer_dirty(parent);
                }
@@ -1498,6 +1518,8 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
                /* update the parent key to reflect our changes */
                struct btrfs_disk_key mid_key;
                btrfs_node_key(mid, &mid_key, 0);
+               tree_mod_log_set_node_key(root->fs_info, parent, &mid_key,
+                                         pslot, 0);
                btrfs_set_node_key(parent, &mid_key, pslot);
                btrfs_mark_buffer_dirty(parent);
        }
@@ -1595,6 +1617,8 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
                        struct btrfs_disk_key disk_key;
                        orig_slot += left_nr;
                        btrfs_node_key(mid, &disk_key, 0);
+                       tree_mod_log_set_node_key(root->fs_info, parent,
+                                                 &disk_key, pslot, 0);
                        btrfs_set_node_key(parent, &disk_key, pslot);
                        btrfs_mark_buffer_dirty(parent);
                        if (btrfs_header_nritems(left) > orig_slot) {
@@ -1646,6 +1670,8 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
                        struct btrfs_disk_key disk_key;
 
                        btrfs_node_key(right, &disk_key, 0);
+                       tree_mod_log_set_node_key(root->fs_info, parent,
+                                                 &disk_key, pslot + 1, 0);
                        btrfs_set_node_key(parent, &disk_key, pslot + 1);
                        btrfs_mark_buffer_dirty(parent);
 
@@ -2348,6 +2374,7 @@ static void fixup_low_keys(struct btrfs_trans_handle *trans,
                if (!path->nodes[i])
                        break;
                t = path->nodes[i];
+               tree_mod_log_set_node_key(root->fs_info, t, key, tslot, 1);
                btrfs_set_node_key(t, key, tslot);
                btrfs_mark_buffer_dirty(path->nodes[i]);
                if (tslot != 0)
@@ -2430,12 +2457,16 @@ static int push_node_left(struct btrfs_trans_handle *trans,
        } else
                push_items = min(src_nritems - 8, push_items);
 
+       tree_mod_log_eb_copy(root->fs_info, dst, src, dst_nritems, 0,
+                            push_items);
        copy_extent_buffer(dst, src,
                           btrfs_node_key_ptr_offset(dst_nritems),
                           btrfs_node_key_ptr_offset(0),
                           push_items * sizeof(struct btrfs_key_ptr));
 
        if (push_items < src_nritems) {
+               tree_mod_log_eb_move(root->fs_info, src, 0, push_items,
+                                    src_nritems - push_items);
                memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
                                      btrfs_node_key_ptr_offset(push_items),
                                      (src_nritems - push_items) *
@@ -2489,11 +2520,14 @@ static int balance_node_right(struct btrfs_trans_handle *trans,
        if (max_push < push_items)
                push_items = max_push;
 
+       tree_mod_log_eb_move(root->fs_info, dst, push_items, 0, dst_nritems);
        memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
                                      btrfs_node_key_ptr_offset(0),
                                      (dst_nritems) *
                                      sizeof(struct btrfs_key_ptr));
 
+       tree_mod_log_eb_copy(root->fs_info, dst, src, 0,
+                            src_nritems - push_items, push_items);
        copy_extent_buffer(dst, src,
                           btrfs_node_key_ptr_offset(0),
                           btrfs_node_key_ptr_offset(src_nritems - push_items),
@@ -2568,6 +2602,7 @@ static noinline int insert_new_root(struct btrfs_trans_handle *trans,
        btrfs_mark_buffer_dirty(c);
 
        old = root->node;
+       tree_mod_log_set_root_pointer(root, c);
        rcu_assign_pointer(root->node, c);
 
        /* the super has an extra ref to root->node */
@@ -2678,6 +2713,7 @@ static noinline int split_node(struct btrfs_trans_handle *trans,
                            (unsigned long)btrfs_header_chunk_tree_uuid(split),
                            BTRFS_UUID_SIZE);
 
+       tree_mod_log_eb_copy(root->fs_info, split, c, 0, mid, c_nritems - mid);
        copy_extent_buffer(split, c,
                           btrfs_node_key_ptr_offset(0),
                           btrfs_node_key_ptr_offset(mid),