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>

1 files changed, 36 insertions, 0 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 72b9f97e2fdc..07c1a96aa4a8 100644
--- 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),