s3: Attempt to fix a deadlock between smbd and ctdbd

In Samba we access the notify databases under the locking.tdb lock when closing a file. This leads to a deadlock with ctdb when doing a recovery.

This is a bad hack, and ctdb will need to get fixed for this. But for now, it
seems necessary.

diff --git a/source/smbd/notify.c b/source/smbd/notify.c
index 180e08655bfc34f2e48195d26a4ab120d6ac857a..8b5a14e42586c933b6a3498da817d35f0f27b990 100644 (file)
--- a/source/smbd/notify.c
+++ b/source/smbd/notify.c
@@ -357,32 +357,98 @@ void remove_pending_change_notify_requests_by_fid(files_struct *fsp,
        }
 }
 
-void notify_fname(connection_struct *conn, uint32 action, uint32 filter,
-                 const char *path)
-{
+struct notify_fname_state {
+       struct notify_context *ctx;
+       uint32_t action;
+       uint32_t filter;
        char *fullpath;
+
+       bool do_onelevel;
+       struct file_id fid;
        char *parent;
        const char *name;
+};
+
+static void notify_fname_callback(struct event_context *ev,
+                                 struct timed_event *te,
+                                 const struct timeval *now,
+                                 void *private_data)
+{
+       struct notify_fname_state *state = talloc_get_type_abort(
+               private_data, struct notify_fname_state);
+
+       DEBUG(10, ("notify_fname_callback called for fullpath=%s, name=%s, "
+                  "action=%d, filter=%d\n", state->fullpath,
+                  state->do_onelevel ? state->name : "::no onelevel",
+                  (int)state->action, (int)state->filter));
+
+       if (state->do_onelevel) {
+               notify_onelevel(state->ctx, state->action, state->filter,
+                               state->fid, state->name);
+       }
+       notify_trigger(state->ctx, state->action, state->filter,
+                      state->fullpath);
+       TALLOC_FREE(te);
+}
+
+void notify_fname(connection_struct *conn, uint32 action, uint32 filter,
+                 const char *path)
+{
+       struct notify_fname_state *state;
        SMB_STRUCT_STAT sbuf;
+       struct timed_event *te;
+       const char *name;
+
+
+       state = talloc(talloc_tos(), struct notify_fname_state);
+       if (state == NULL) {
+               return;
+       }
+       state->ctx = conn->notify_ctx;
+       state->action = action;
+       state->filter = filter;
 
        if (path[0] == '.' && path[1] == '/') {
                path += 2;
        }
-       if (asprintf(&fullpath, "%s/%s", conn->connectpath, path) == -1) {
-               DEBUG(0, ("asprintf failed\n"));
+
+       state->fullpath = talloc_asprintf(state, "%s/%s", conn->connectpath,
+                                         path);
+       if (state->fullpath == NULL) {
+               TALLOC_FREE(state);
+               DEBUG(0, ("talloc_asprintf failed\n"));
                return;
        }
 
-       if (parent_dirname_talloc(talloc_tos(), path, &parent, &name)
-           && (SMB_VFS_STAT(conn, parent, &sbuf) != -1)) {
-               notify_onelevel(conn->notify_ctx, action, filter,
-                               SMB_VFS_FILE_ID_CREATE(conn, sbuf.st_dev,
-                                                      sbuf.st_ino),
-                               name);
+       if (parent_dirname_talloc(state, path, &state->parent, &name)
+           && (SMB_VFS_STAT(conn, state->parent, &sbuf) != -1)) {
+               state->do_onelevel = true;
+               state->name = talloc_strdup(state, name);
+               if (state->name == NULL) {
+                       DEBUG(0, ("talloc_strdup failed\n"));
+                       TALLOC_FREE(state);
+                       return;
+               }
+               state->fid = SMB_VFS_FILE_ID_CREATE(conn, sbuf.st_dev,
+                                                   sbuf.st_ino);
+       } else {
+               state->do_onelevel = false;
        }
 
-       notify_trigger(conn->notify_ctx, action, filter, fullpath);
-       SAFE_FREE(fullpath);
+       DEBUG(10, ("notify_fname created for fullpath=%s, name=%s, "
+                  "action=%d, filter=%d\n", state->fullpath,
+                  state->do_onelevel ? state->name : "::no onelevel",
+                  (int)state->action, (int)state->filter));
+
+       te = event_add_timed(smbd_event_context(), NULL, timeval_zero(),
+                            "notify_fname_callback", notify_fname_callback,
+                            state);
+       if (te == NULL) {
+               DEBUG(10, ("event_add_timed failed\n"));
+               TALLOC_FREE(state);
+               return;
+       }
+       state = talloc_move(te, &state);
 }
 
 static void notify_fsp(files_struct *fsp, uint32 action, const char *name)