CIFS: fix deadlock in cached root handling

	smb2_set_related(&rqst[1]);

	/*

	 * We do not hold the lock for the open because in case

	 * SMB2_open needs to reconnect, it will end up calling

	 * cifs_mark_open_files_invalid() which takes the lock again

	 * thus causing a deadlock

	 */

	mutex_unlock(&tcon->crfid.fid_mutex);

	rc = compound_send_recv(xid, ses, flags, 2, rqst,

				resp_buftype, rsp_iov);

	mutex_lock(&tcon->crfid.fid_mutex);

	/*

	 * Now we need to check again as the cached root might have

	 * been successfully re-opened from a concurrent process

	 */

	if (tcon->crfid.is_valid) {

		/* work was already done */

		/* stash fids for close() later */

		struct cifs_fid fid = {

			.persistent_fid = pfid->persistent_fid,

			.volatile_fid = pfid->volatile_fid,

		};

		/*

		 * caller expects this func to set pfid to a valid

		 * cached root, so we copy the existing one and get a

		 * reference.

		 */

		memcpy(pfid, tcon->crfid.fid, sizeof(*pfid));

		kref_get(&tcon->crfid.refcount);

		mutex_unlock(&tcon->crfid.fid_mutex);

		if (rc == 0) {

			/* close extra handle outside of crit sec */

			SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);

		}

		goto oshr_free;

	}

	/* Cached root is still invalid, continue normaly */

	if (rc)

		goto oshr_exit;

oshr_exit:

	mutex_unlock(&tcon->crfid.fid_mutex);

oshr_free:

	SMB2_open_free(&rqst[0]);

	SMB2_query_info_free(&rqst[1]);

	free_rsp_buf(resp_buftype[0], rsp_iov[0].iov_base);