Merge branch 'for-next' into for-linus

1 files changed, 13 insertions, 12 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index cd2d36580f1a..2801c991814f 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3295,21 +3295,22 @@ void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
 		}
 
 		/*
-		 * If this is a leaf and there are tree mod log users, we may
-		 * have recorded mod log operations that point to this leaf.
-		 * So we must make sure no one reuses this leaf's extent before
-		 * mod log operations are applied to a node, otherwise after
-		 * rewinding a node using the mod log operations we get an
-		 * inconsistent btree, as the leaf's extent may now be used as
-		 * a node or leaf for another different btree.
+		 * If there are tree mod log users we may have recorded mod log
+		 * operations for this node.  If we re-allocate this node we
+		 * could replay operations on this node that happened when it
+		 * existed in a completely different root.  For example if it
+		 * was part of root A, then was reallocated to root B, and we
+		 * are doing a btrfs_old_search_slot(root b), we could replay
+		 * operations that happened when the block was part of root A,
+		 * giving us an inconsistent view of the btree.
+		 *
 		 * We are safe from races here because at this point no other
 		 * node or root points to this extent buffer, so if after this
-		 * check a new tree mod log user joins, it will not be able to
-		 * find a node pointing to this leaf and record operations that
-		 * point to this leaf.
+		 * check a new tree mod log user joins we will not have an
+		 * existing log of operations on this node that we have to
+		 * contend with.
 		 */
-		if (btrfs_header_level(buf) == 0 &&
-		    test_bit(BTRFS_FS_TREE_MOD_LOG_USERS, &fs_info->flags))
+		if (test_bit(BTRFS_FS_TREE_MOD_LOG_USERS, &fs_info->flags))
 			must_pin = true;
 
 		if (must_pin || btrfs_is_zoned(fs_info)) {