Btrfs: protect orphan block rsv with spin_lock (90290e19) · Commits · 戴 / test

We've been seeing warnings coming out of the orphan commit stuff forever from ceph. Turns out it's because we're racing with checking if the orphan block reserve is set, because we clear it outside of the spin_lock. So leave the normal fastpath checks where they are, but take the spin_lock and _recheck_ to make sure we haven't had an orphan block rsv added in the meantime. Then clear the root's orphan block rsv and release the lock. With this patch a user said the warnings went away and they usually showed up pretty soon after he started ceph. Thanks, Signed-off-by:

Josef Bacik <josef@redhat.com>

fs/btrfs/inode.c

+19 −4

Original line number	Diff line number	Diff line
		@@ -1951,12 +1951,28 @@ enum btrfs_orphan_cleanup_state {
		void btrfs_orphan_commit_root(struct btrfs_trans_handle *trans,
		struct btrfs_root *root)
		{
		struct btrfs_block_rsv *block_rsv;
		int ret;

		if (!list_empty(&root->orphan_list) \|\|
		root->orphan_cleanup_state != ORPHAN_CLEANUP_DONE)
		return;

		spin_lock(&root->orphan_lock);
		if (!list_empty(&root->orphan_list)) {
		spin_unlock(&root->orphan_lock);
		return;
		}

		if (root->orphan_cleanup_state != ORPHAN_CLEANUP_DONE) {
		spin_unlock(&root->orphan_lock);
		return;
		}

		block_rsv = root->orphan_block_rsv;
		root->orphan_block_rsv = NULL;
		spin_unlock(&root->orphan_lock);

		if (root->orphan_item_inserted &&
		btrfs_root_refs(&root->root_item) > 0) {
		ret = btrfs_del_orphan_item(trans, root->fs_info->tree_root,
		@@ -1965,10 +1981,9 @@ void btrfs_orphan_commit_root(struct btrfs_trans_handle *trans,
		root->orphan_item_inserted = 0;
		}

		if (root->orphan_block_rsv) {
		WARN_ON(root->orphan_block_rsv->size > 0);
		btrfs_free_block_rsv(root, root->orphan_block_rsv);
		root->orphan_block_rsv = NULL;
		if (block_rsv) {
		WARN_ON(block_rsv->size > 0);
		btrfs_free_block_rsv(root, block_rsv);
		}
		}

Admin message