From: Josef Bacik Date: Mon, 1 Jul 2013 20:10:16 +0000 (-0400) Subject: Btrfs: only do the tree_mod_log_free_eb if this is our last ref X-Git-Tag: firefly_0821_release~176^2~5757^2~1 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=7fb7d76f96bfcbea25007d190ba828b18e13d29d;p=firefly-linux-kernel-4.4.55.git Btrfs: only do the tree_mod_log_free_eb if this is our last ref There is another bug in the tree mod log stuff in that we're calling tree_mod_log_free_eb every single time a block is cow'ed. The problem with this is that if this block is shared by multiple snapshots we will call this multiple times per block, so if we go to rewind the mod log for this block we'll BUG_ON() in __tree_mod_log_rewind because we try to rewind a free twice. We only want to call tree_mod_log_free_eb if we are actually freeing the block. With this patch I no longer hit the panic in __tree_mod_log_rewind. Thanks, Cc: stable@vger.kernel.org Reviewed-by: Jan Schmidt Signed-off-by: Josef Bacik --- diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 7921e1d9d59c..5bf4c39e2ad6 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1089,7 +1089,8 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans, btrfs_set_node_ptr_generation(parent, parent_slot, trans->transid); btrfs_mark_buffer_dirty(parent); - tree_mod_log_free_eb(root->fs_info, buf); + if (last_ref) + tree_mod_log_free_eb(root->fs_info, buf); btrfs_free_tree_block(trans, root, buf, parent_start, last_ref); }