--- /dev/null
+#
+# This is a dot (http://www.graphviz.org) description of the various
+# states volumes can be in for DAFS (Demand Attach File Server).
+#
+# Author: Tom Keiser
+# Date: 2008-06-03
+#
+
+digraph VolumeStates {
+ size="11,17"
+ graph [
+ rankdir = "TB"
+ ];
+
+ subgraph clusterKey {
+ rankdir="LR";
+ shape = "rectangle";
+
+ s1 [ shape=plaintext, label = "VAllocVnode",
+ fontcolor="brown" ];
+ s2 [ shape=plaintext, label = "VGetVnode",
+ fontcolor="blue" ];
+ s3 [ shape=plaintext, label = "VPutVnode",
+ fontcolor="purple" ];
+ s4 [ shape=plaintext, label = "Error States",
+ fontcolor="red" ];
+ s5 [ shape=plaintext, label = "VVnodeWriteToRead",
+ fontcolor="green" ];
+ s6 [ shape=ellipse, label = "re-entrant" ];
+ s7 [ shape=ellipse, peripheries=2, label="non re-entrant" ];
+ s8 [ shape=ellipse, color="red", label="Error States" ];
+
+ s6->s7->s8->s1->s2->s3->s5->s4 [style="invis"];
+
+ }
+
+ node [ peripheries = "2" ] \
+ RELEASING ALLOC LOADING EXCLUSIVE STORE ;
+ node [ shape = "ellipse", peripheries = "1" ];
+ node [ color = "red" ] ERROR ;
+
+ node [ color = "black" ]; // default back to black
+
+
+ // node descriptions
+ INVALID [ label = "Vn_state(vnp) == VN_STATE_INVALID\n(vnode cache entry is invalid)" ];
+ RELEASING [ label = "Vn_state(vnp) == VN_STATE_RELEASING\n(vnode is busy releasing its inode handle ref)" ];
+ ALLOC [ label = "Vn_state(vnp) == VN_STATE_ALLOC\n(vnode is busy allocating disk entry)" ];
+ ALLOC_read [ label = "reading stale vnode from disk\nto verify inactive state" ];
+ ALLOC_extend [ label = "extending vnode index file" ];
+ ONLINE [ label = "Vn_state(vnp) == VN_STATE_ONLINE\n(vnode is a valid cache entry)" ];
+ LOADING [ label = "Vn_state(vnp) == VN_STATE_LOAD\n(vnode is busy loading from disk)" ];
+ EXCLUSIVE [ label = "Vn_state(vnp) == VN_STATE_EXCLUSIVE\n(vnode is owned exclusively by an external caller)" ];
+ STORE [ label = "Vn_state(vnp) == VN_STATE_STORE\n(vnode is busy writing to disk)" ];
+ READ [ label = "Vn_state(vnp) == VN_STATE_READ\n(vnode is shared by several external callers)" ];
+ ERROR [ label = "Vn_state(vnp) == VN_STATE_ERROR\n(vnode hard error state)" ];
+
+
+ ONLINE->RELEASING [ label = "VGetFreeVnode_r()" ];
+ RELEASING->INVALID [ label = "VGetFreeVnode_r()" ];
+
+ INVALID->ALLOC [ color="brown", label="vnode not in cache; allocating" ];
+ ONLINE->EXCLUSIVE [ color="brown", label="vnode in cache" ];
+ ALLOC->ALLOC_read [ color="brown", label="vnode index is within present file size" ];
+ ALLOC->ALLOC_extend [ color="brown", label="vnode index is beyond end of file" ];
+ ALLOC_read->EXCLUSIVE [ color="brown" ];
+ ALLOC_extend->EXCLUSIVE [ color="brown" ];
+ ALLOC_read->INVALID [ color="red", label="I/O error; invalidating vnode\nand scheduling salvage" ];
+ ALLOC_extend->INVALID [ color="red", label="I/O error; invalidating vnode\nand scheduling salvage" ];
+
+ INVALID->LOADING [ color="blue", label="vnode not cached" ];
+ LOADING->INVALID [ color="red", label="I/O error; invalidating vnode\nand scheduling salvage" ];
+ LOADING->ONLINE [ color="blue" ];
+ ONLINE->READ [ color="blue", label="caller requested read lock" ];
+ ONLINE->EXCLUSIVE [ color="blue", label="caller requested write lock" ];
+
+ EXCLUSIVE->READ [ color="green", label="vnode not changed" ];
+ EXCLUSIVE->STORE [ color="green", label="vnode changed" ];
+ EXCLUSIVE->ONLINE [ color="purple", label="vnode not changed" ];
+ EXCLUSIVE->STORE [ color="purple", label="vnode changed" ];
+
+ STORE->READ [ color="green" ];
+ STORE->ONLINE [ color="purple" ];
+ STORE->ERROR [ color="red", label="I/O error; scheduling salvage" ];
+
+ READ->READ [ color="blue", label="Vn_readers(vnp) > 0" ];
+ READ->READ [ color="purple", label="Vn_readers(vnp) > 1" ];
+ READ->ONLINE [ color="purple", label="Vn_readers(vnp) == 1" ];
+}