ocfs2: Introduce the DOWN message to ocfs2_control

When the control daemon sees a node go down, it sends a DOWN message
through the ocfs2_control device.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

1 files changed, 89 insertions, 5 deletions

diff --git a/fs/ocfs2/stack_user.c b/fs/ocfs2/stack_user.c
index ff8d30757924..a5e58e2b9d59 100644
--- a/fs/ocfs2/stack_user.c
+++ b/fs/ocfs2/stack_user.c
@@ -35,9 +35,21 @@
  * of output is a supported protocol tag.  All protocol tags are a single
  * character followed by a two hex digit version number.  Currently the
  * only things supported is T01, for "Text-base version 0x01".  Next, the
- * client writes the version they would like to use.  If the version tag
- * written is unknown, -EINVAL is returned.  Once the negotiation is
- * complete, the client can start sending messages.
+ * client writes the version they would like to use, including the newline.
+ * Thus, the protocol tag is 'T01\n'.  If the version tag written is
+ * unknown, -EINVAL is returned.  Once the negotiation is complete, the
+ * client can start sending messages.
+ *
+ * The T01 protocol only has one message, "DOWN".  It has the following
+ * syntax:
+ *
+ *  DOWN<space><32-char-cap-hex-uuid><space><8-char-hex-nodenum><newline>
+ *
+ * eg:
+ *
+ *  DOWN 632A924FDD844190BDA93C0DF6B94899 00000001\n
+ *
+ * This is 47 characters.
  */
 
 /*
@@ -49,6 +61,11 @@
 #define OCFS2_CONTROL_HANDSHAKE_INVALID         (0)
 #define OCFS2_CONTROL_HANDSHAKE_READ            (1)
 #define OCFS2_CONTROL_HANDSHAKE_VALID           (2)
+#define OCFS2_CONTROL_MESSAGE_DOWN              "DOWN"
+#define OCFS2_CONTROL_MESSAGE_DOWN_LEN          4
+#define OCFS2_CONTROL_MESSAGE_DOWN_TOTAL_LEN    47
+#define OCFS2_TEXT_UUID_LEN                     32
+#define OCFS2_CONTROL_MESSAGE_NODENUM_LEN       8
 
 /*
  * ocfs2_live_connection is refcounted because the filesystem and
@@ -149,7 +166,7 @@ static void ocfs2_live_connection_drop(struct ocfs2_live_connection *c)
         kfree(c);
 }
 
-static ssize_t ocfs2_control_cfu(char *target, size_t target_len,
+static ssize_t ocfs2_control_cfu(void *target, size_t target_len,
                                  const char __user *buf, size_t count)
 {
         /* The T01 expects write(2) calls to have exactly one command */
@@ -185,6 +202,73 @@ static ssize_t ocfs2_control_validate_handshake(struct file *file,
         return count;
 }
 
+static void ocfs2_control_send_down(const char *uuid,
+                                    int nodenum)
+{
+        struct ocfs2_live_connection *c;
+
+        mutex_lock(&ocfs2_control_lock);
+
+        c = ocfs2_connection_find(uuid);
+        if (c) {
+                BUG_ON(c->oc_conn == NULL);
+                c->oc_conn->cc_recovery_handler(nodenum,
+                                                c->oc_conn->cc_recovery_data);
+        }
+
+        mutex_unlock(&ocfs2_control_lock);
+}
+
+/* DOWN<space><32-char-cap-hex-uuid><space><8-char-hex-nodenum><newline> */
+struct ocfs2_control_message_down {
+        char    tag[OCFS2_CONTROL_MESSAGE_DOWN_LEN];
+        char    space1;
+        char    uuid[OCFS2_TEXT_UUID_LEN];
+        char    space2;
+        char    nodestr[OCFS2_CONTROL_MESSAGE_NODENUM_LEN];
+        char    newline;
+};
+
+static ssize_t ocfs2_control_message(struct file *file,
+                                     const char __user *buf,
+                                     size_t count)
+{
+        ssize_t ret;
+        char *p = NULL;
+        long nodenum;
+        struct ocfs2_control_message_down msg;
+
+        /* Try to catch padding issues */
+        WARN_ON(offsetof(struct ocfs2_control_message_down, uuid) !=
+                (sizeof(msg.tag) + sizeof(msg.space1)));
+
+        memset(&msg, 0, sizeof(struct ocfs2_control_message_down));
+        ret = ocfs2_control_cfu(&msg, OCFS2_CONTROL_MESSAGE_DOWN_TOTAL_LEN,
+                                buf, count);
+        if (ret != count)
+                return ret;
+
+        if (strncmp(msg.tag, OCFS2_CONTROL_MESSAGE_DOWN,
+                    strlen(OCFS2_CONTROL_MESSAGE_DOWN)))
+                return -EINVAL;
+
+        if ((msg.space1 != ' ') || (msg.space2 != ' ') ||
+            (msg.newline != '\n'))
+                return -EINVAL;
+        msg.space1 = msg.space2 = msg.newline = '\0';
+
+        nodenum = simple_strtol(msg.nodestr, &p, 16);
+        if (!p || *p)
+                return -EINVAL;
+
+        if ((nodenum == LONG_MIN) || (nodenum == LONG_MAX) ||
+            (nodenum > INT_MAX) || (nodenum < 0))
+                return -ERANGE;
+
+        ocfs2_control_send_down(msg.uuid, nodenum);
+
+        return count;
+}
 
 static ssize_t ocfs2_control_write(struct file *file,
                                    const char __user *buf,
@@ -204,7 +288,7 @@ static ssize_t ocfs2_control_write(struct file *file,
                         break;
 
                 case OCFS2_CONTROL_HANDSHAKE_VALID:
-                        ret = count;  /* XXX */
+                        ret = ocfs2_control_message(file, buf, count);
                         break;
 
                 default: