1 files changed, 55 insertions, 15 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index b33436211000..cdfb4c49a806 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -596,6 +596,11 @@ tree_mod_log_insert_move(struct btrfs_fs_info *fs_info,
         if (tree_mod_dont_log(fs_info, eb))
                 return 0;
 
+        /*
+         * When we override something during the move, we log these removals.
+         * This can only happen when we move towards the beginning of the
+         * buffer, i.e. dst_slot < src_slot.
+         */
         for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
                 ret = tree_mod_log_insert_key_locked(fs_info, eb, i + dst_slot,
                                               MOD_LOG_KEY_REMOVE_WHILE_MOVING);
@@ -647,8 +652,6 @@ tree_mod_log_insert_root(struct btrfs_fs_info *fs_info,
         if (tree_mod_dont_log(fs_info, NULL))
                 return 0;
 
-        __tree_mod_log_free_eb(fs_info, old_root);
-
         ret = tree_mod_alloc(fs_info, flags, &tm);
         if (ret < 0)
                 goto out;
@@ -926,12 +929,7 @@ 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);
+                tree_mod_log_free_eb(root->fs_info, buf);
                 clean_tree_block(trans, root, buf);
                 *last_ref = 1;
         }
@@ -1225,6 +1223,8 @@ tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
         free_extent_buffer(eb);
 
         __tree_mod_log_rewind(eb_rewin, time_seq, tm);
+        WARN_ON(btrfs_header_nritems(eb_rewin) >
+                BTRFS_NODEPTRS_PER_BLOCK(fs_info->fs_root));
 
         return eb_rewin;
 }
@@ -1241,9 +1241,11 @@ get_old_root(struct btrfs_root *root, u64 time_seq)
 {
         struct tree_mod_elem *tm;
         struct extent_buffer *eb;
+        struct extent_buffer *old;
         struct tree_mod_root *old_root = NULL;
         u64 old_generation = 0;
         u64 logical;
+        u32 blocksize;
 
         eb = btrfs_read_lock_root_node(root);
         tm = __tree_mod_log_oldest_root(root->fs_info, root, time_seq);
@@ -1259,14 +1261,32 @@ get_old_root(struct btrfs_root *root, u64 time_seq)
         }
 
         tm = tree_mod_log_search(root->fs_info, logical, time_seq);
-        if (old_root)
+        if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
+                btrfs_tree_read_unlock(root->node);
+                free_extent_buffer(root->node);
+                blocksize = btrfs_level_size(root, old_root->level);
+                old = read_tree_block(root, logical, blocksize, 0);
+                if (!old) {
+                        pr_warn("btrfs: failed to read tree block %llu from get_old_root\n",
+                                logical);
+                        WARN_ON(1);
+                } else {
+                        eb = btrfs_clone_extent_buffer(old);
+                        free_extent_buffer(old);
+                }
+        } else if (old_root) {
+                btrfs_tree_read_unlock(root->node);
+                free_extent_buffer(root->node);
                 eb = alloc_dummy_extent_buffer(logical, root->nodesize);
-        else
+        } else {
                 eb = btrfs_clone_extent_buffer(root->node);
-        btrfs_tree_read_unlock(root->node);
-        free_extent_buffer(root->node);
+                btrfs_tree_read_unlock(root->node);
+                free_extent_buffer(root->node);
+        }
+
         if (!eb)
                 return NULL;
+        extent_buffer_get(eb);
         btrfs_tree_read_lock(eb);
         if (old_root) {
                 btrfs_set_header_bytenr(eb, eb->start);
@@ -1279,11 +1299,28 @@ get_old_root(struct btrfs_root *root, u64 time_seq)
                 __tree_mod_log_rewind(eb, time_seq, tm);
         else
                 WARN_ON(btrfs_header_level(eb) != 0);
-        extent_buffer_get(eb);
+        WARN_ON(btrfs_header_nritems(eb) > BTRFS_NODEPTRS_PER_BLOCK(root));
 
         return eb;
 }
 
+int btrfs_old_root_level(struct btrfs_root *root, u64 time_seq)
+{
+        struct tree_mod_elem *tm;
+        int level;
+
+        tm = __tree_mod_log_oldest_root(root->fs_info, root, time_seq);
+        if (tm && tm->op == MOD_LOG_ROOT_REPLACE) {
+                level = tm->old_root.level;
+        } else {
+                rcu_read_lock();
+                level = btrfs_header_level(root->node);
+                rcu_read_unlock();
+        }
+
+        return level;
+}
+
 static inline int should_cow_block(struct btrfs_trans_handle *trans,
                                    struct btrfs_root *root,
                                    struct extent_buffer *buf)
@@ -1725,6 +1762,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
                         goto enospc;
                 }
 
+                tree_mod_log_free_eb(root->fs_info, root->node);
                 tree_mod_log_set_root_pointer(root, child);
                 rcu_assign_pointer(root->node, child);
 
@@ -2970,8 +3008,10 @@ static int push_node_left(struct btrfs_trans_handle *trans,
                            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);
+                /*
+                 * don't call tree_mod_log_eb_move here, key removal was already
+                 * fully logged by tree_mod_log_eb_copy above.
+                 */
                 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
                                       btrfs_node_key_ptr_offset(push_items),
                                       (src_nritems - push_items) *