Commit b37b39cd authored Jul 23, 2013 by Josef Bacik Committed by Chris Mason Sep 01, 2013

Btrfs: cleanup reloc roots properly on error

I was hitting the BUG_ON() at the end of merge_reloc_roots() because we were
aborting the transaction at some point previously and then getting an error when
we tried to drop the reloc root. I fixed btrfs_drop_snapshot to re-add us to
the dead roots list if we failed, but this isn't the right thing to do for reloc
roots since it uses root->root_list for it's own stuff in order to know what
needs to be cleaned up. So fix btrfs_drop_snapshot to only do the re-add if we
aren't dropping for reloc, and handle errors from merge_reloc_root() by dropping
the reloc root we are processing since it won't be on the list of roots to
cleanup. With this patch my reproducer no longer panics. Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

parent 50f1319c

fs/btrfs/extent-tree.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -7696,7 +7696,7 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
		* don't have it in the radix (like when we recover after a power fail
		* or unmount) so we don't leak memory.
		*/
		if (root_dropped == false)
		if (!for_reloc && root_dropped == false)
		btrfs_add_dead_root(root);
		if (err)
		btrfs_std_error(root->fs_info, err);

fs/btrfs/relocation.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -2314,8 +2314,13 @@ int merge_reloc_roots(struct reloc_control *rc)
		BUG_ON(root->reloc_root != reloc_root);

		ret = merge_reloc_root(rc, root);
		if (ret)
		if (ret) {
		__update_reloc_root(reloc_root, 1);
		free_extent_buffer(reloc_root->node);
		free_extent_buffer(reloc_root->commit_root);
		kfree(reloc_root);
		goto out;
		}
		} else {
		list_del_init(&reloc_root->root_list);
		}