Fix a bug where LSM would get the same lock twice during a drop.

1 files changed, 22 insertions, 10 deletions

diff --git a/src/lsm/lsm_worker.c b/src/lsm/lsm_worker.c
index e29607f9901..cc38f80e746 100644
--- a/src/lsm/lsm_worker.c
+++ b/src/lsm/lsm_worker.c
@@ -434,14 +434,12 @@ __lsm_drop_file(WT_SESSION_IMPL *session, const char *uri)
 {
 	WT_CONNECTION_IMPL *conn;
 	WT_DECL_RET;
-	int hot_backup_locked;
 	const char *drop_cfg[] = {
 	    WT_CONFIG_BASE(session, session_drop), "remove_files=false", NULL
 	};
 
 	conn = S2C(session);
-	hot_backup_locked = 0;
-	/* Give up if a hot backup is in progress. */
+	/* Give up early if a hot backup is in progress. */
 	if (conn->hot_backup != 0)
 		return (EBUSY);
 
@@ -453,18 +451,32 @@ __lsm_drop_file(WT_SESSION_IMPL *session, const char *uri)
 	WT_RET(__lsm_discard_handle(session, uri, NULL));
 	WT_RET(__lsm_discard_handle(session, uri, "WiredTigerCheckpoint"));
 
+	/*
+	 * Take the hot backup lock to prevent new backups starting. Don't
+	 * proceed if a backup has started since we first checked.
+	 */
 	__wt_spin_lock(session, &conn->hot_backup_lock);
-	hot_backup_locked = 1;
-	if (conn->hot_backup != 0)
-		goto done;
-	WT_WITH_SCHEMA_LOCK(session,
-	    ret = __wt_schema_drop(session, uri, drop_cfg));
+	if (conn->hot_backup != 0) {
+		__wt_spin_unlock(session, &conn->hot_backup_lock);
+		return (EBUSY);
+	}
+
+	/*
+	 * Take the schema lock for the drop operation. Play games with the
+	 * hot backup lock. Since __wt_schema_drop results in the hot backup
+	 * lock being taken when it updates the metadata (which would be too
+	 * late to prevent our drop).
+	 */
+	__wt_spin_lock(session, &S2C(session)->schema_lock);
+	F_SET(session, WT_SESSION_SCHEMA_LOCKED);	
+	__wt_spin_unlock(session, &conn->hot_backup_lock);
+	ret = __wt_schema_drop(session, uri, drop_cfg);
+	F_CLR(session, WT_SESSION_SCHEMA_LOCKED);
+	__wt_spin_unlock(session, &S2C(session)->schema_lock);
 
 	if (ret == 0)
 		ret = __wt_remove(session, uri + strlen("file:"));
 
-done:	if (hot_backup_locked)
-		__wt_spin_unlock(session, &conn->hot_backup_lock);
 	return (ret);
 }