drbd: Extracted is_valid_transition() out of sanitize_state()

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

diff --git a/drivers/block/drbd/drbd_state.c b/drivers/block/drbd/drbd_state.c
index d5777159a2b162dbe656247ea6d4dfe756091a4c..3199bf92e46ea4ec4876f13638e438805b5080a9 100644 (file)
--- a/drivers/block/drbd/drbd_state.c
+++ b/drivers/block/drbd/drbd_state.c
@@ -47,6 +47,7 @@ static void after_conn_state_ch(struct drbd_tconn *tconn, union drbd_state os,
                                union drbd_state ns, enum chg_state_flags flags);
 static enum drbd_state_rv is_valid_state(struct drbd_conf *, union drbd_state);
 static enum drbd_state_rv is_valid_soft_transition(union drbd_state, union drbd_state);
+static enum drbd_state_rv is_valid_transition(union drbd_state os, union drbd_state ns);
 static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state os,
                                       union drbd_state ns, const char **warn_sync_abort);
 
@@ -112,15 +113,17 @@ _req_st_cond(struct drbd_conf *mdev, union drbd_state mask,
        if (test_and_clear_bit(CL_ST_CHG_FAIL, &mdev->flags))
                return SS_CW_FAILED_BY_PEER;
 
-       rv = 0;
        spin_lock_irqsave(&mdev->tconn->req_lock, flags);
        os = mdev->state;
        ns.i = (os.i & ~mask.i) | val.i;
        ns = sanitize_state(mdev, os, ns, NULL);
+       rv = is_valid_transition(os, ns);
+       if (rv == SS_SUCCESS)
+               rv = SS_UNKNOWN_ERROR;  /* cont waiting, otherwise fail. */
 
        if (!cl_wide_st_chg(mdev, os, ns))
                rv = SS_CW_NO_NEED;
-       if (!rv) {
+       if (rv == SS_UNKNOWN_ERROR) {
                rv = is_valid_state(mdev, ns);
                if (rv == SS_SUCCESS) {
                        rv = is_valid_soft_transition(os, ns);
@@ -160,8 +163,10 @@ drbd_req_state(struct drbd_conf *mdev, union drbd_state mask,
        spin_lock_irqsave(&mdev->tconn->req_lock, flags);
        os = mdev->state;
        ns.i = (os.i & ~mask.i) | val.i;
-
        ns = sanitize_state(mdev, os, ns, NULL);
+       rv = is_valid_transition(os, ns);
+       if (rv < SS_SUCCESS)
+               goto abort;
 
        if (cl_wide_st_chg(mdev, os, ns)) {
                rv = is_valid_state(mdev, ns);
@@ -340,6 +345,8 @@ is_valid_state(struct drbd_conf *mdev, union drbd_state ns)
 
 /**
  * is_valid_soft_transition() - Returns an SS_ error code if the state transition is not possible
+ * This function limits state transitions that may be declined by DRBD. I.e.
+ * user requests (aka soft transitions).
  * @mdev:      DRBD device.
  * @ns:                new state.
  * @os:                old state.
@@ -389,6 +396,40 @@ is_valid_soft_transition(union drbd_state os, union drbd_state ns)
        return rv;
 }
 
+/**
+ * is_valid_transition() - Returns an SS_ error code if the state transition is not possible
+ * This limits hard state transitions. Hard state transitions are facts there are
+ * imposed on DRBD by the environment. E.g. disk broke or network broke down.
+ * But those hard state transitions are still not allowed to do everything.
+ * @ns:                new state.
+ * @os:                old state.
+ */
+static enum drbd_state_rv
+is_valid_transition(union drbd_state os, union drbd_state ns)
+{
+       enum drbd_state_rv rv = SS_SUCCESS;
+
+       /* Disallow Network errors to configure a device's network part */
+       if ((ns.conn >= C_TIMEOUT && ns.conn <= C_TEAR_DOWN) &&
+           os.conn <= C_DISCONNECTING)
+               rv = SS_NEED_CONNECTION;
+
+       /* After a network error only C_UNCONNECTED or C_DISCONNECTING may follow. */
+       if (os.conn >= C_TIMEOUT && os.conn <= C_TEAR_DOWN &&
+           ns.conn != C_UNCONNECTED && ns.conn != C_DISCONNECTING)
+               rv = SS_IN_TRANSIENT_STATE;
+
+       /* After C_DISCONNECTING only C_STANDALONE may follow */
+       if (os.conn == C_DISCONNECTING && ns.conn != C_STANDALONE)
+               rv = SS_IN_TRANSIENT_STATE;
+
+       /* we cannot fail (again) if we already detached */
+       if (ns.disk == D_FAILED && os.disk == D_DISKLESS)
+               rv = SS_IS_DISKLESS;
+
+       return rv;
+}
+
 /**
  * sanitize_state() - Resolves implicitly necessary additional changes to a state transition
  * @mdev:      DRBD device.
@@ -411,30 +452,12 @@ static union drbd_state sanitize_state(struct drbd_conf *mdev, union drbd_state
                put_ldev(mdev);
        }
 
-       /* Disallow Network errors to configure a device's network part */
-       if ((ns.conn >= C_TIMEOUT && ns.conn <= C_TEAR_DOWN) &&
-           os.conn <= C_DISCONNECTING)
-               ns.conn = os.conn;
-
-       /* After a network error (+C_TEAR_DOWN) only C_UNCONNECTED or C_DISCONNECTING can follow.
-        * If you try to go into some Sync* state, that shall fail (elsewhere). */
-       if (os.conn >= C_TIMEOUT && os.conn <= C_TEAR_DOWN &&
-           ns.conn != C_UNCONNECTED && ns.conn != C_DISCONNECTING && ns.conn <= C_TEAR_DOWN)
-               ns.conn = os.conn;
-
-       /* we cannot fail (again) if we already detached */
-       if (ns.disk == D_FAILED && os.disk == D_DISKLESS)
-               ns.disk = D_DISKLESS;
-
        /* if we are only D_ATTACHING yet,
         * we can (and should) go directly to D_DISKLESS. */
        if (ns.disk == D_FAILED && os.disk == D_ATTACHING)
                ns.disk = D_DISKLESS;
 
-       /* After C_DISCONNECTING only C_STANDALONE may follow */
-       if (os.conn == C_DISCONNECTING && ns.conn != C_STANDALONE)
-               ns.conn = os.conn;
-
+       /* Implications from connection to peer and peer_isp */
        if (ns.conn < C_CONNECTED) {
                ns.peer_isp = 0;
                ns.peer = R_UNKNOWN;
@@ -641,6 +664,10 @@ __drbd_set_state(struct drbd_conf *mdev, union drbd_state ns,
        if (ns.i == os.i)
                return SS_NOTHING_TO_DO;
 
+       rv = is_valid_transition(os, ns);
+       if (rv < SS_SUCCESS)
+               return rv;
+
        if (!(flags & CS_HARD)) {
                /*  pre-state-change checks ; only look at ns  */
                /* See drbd_state_sw_errors in drbd_strings.c */