Commit 8351583e authored Jun 14, 2011 by Josef Bacik

Btrfs: protect the pending_snapshots list with trans_lock

Currently there is nothing protecting the pending_snapshots list on the
transaction. We only hold the directory mutex that we are snapshotting and a
read lock on the subvol_sem, so we could race with somebody else creating a
snapshot in a different directory and end up with list corruption. So protect
this list with the trans_lock. Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>

parent 71d7aed0

fs/btrfs/ioctl.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -482,8 +482,10 @@ static int create_snapshot(struct btrfs_root root, struct dentry dentry,
		ret = btrfs_snap_reserve_metadata(trans, pending_snapshot);
		BUG_ON(ret);

		spin_lock(&root->fs_info->trans_lock);
		list_add(&pending_snapshot->list,
		&trans->transaction->pending_snapshots);
		spin_unlock(&root->fs_info->trans_lock);
		if (async_transid) {
		*async_transid = trans->transid;
		ret = btrfs_commit_transaction_async(trans,

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