doc/txt/dafs-vnode-fsa.dot

   1 #
   2 # This is a dot (http://www.graphviz.org) description of the various
   3 # states volumes can be in for DAFS (Demand Attach File Server).
   4 #
   5 # Author: Tom Keiser
   6 # Date: 2008-06-03
   7 #
   8
   9 digraph VolumeStates {
  10         size="11,17"
  11         graph [
  12                 rankdir = "TB"
  13         ];
  14
  15         subgraph clusterKey {
  16                 rankdir="LR";
  17                 shape = "rectangle";
  18
  19         s1 [ shape=plaintext, label = "VAllocVnode",
  20                         fontcolor="brown" ];
  21         s2 [ shape=plaintext, label = "VGetVnode",
  22                         fontcolor="blue" ];
  23         s3 [ shape=plaintext, label = "VPutVnode",
  24                         fontcolor="purple" ];
  25         s4 [ shape=plaintext, label = "Error States",
  26                         fontcolor="red" ];
  27         s5 [ shape=plaintext, label = "VVnodeWriteToRead",
  28                         fontcolor="green" ];
  29         s6 [ shape=ellipse, label = "re-entrant" ];
  30         s7 [ shape=ellipse, peripheries=2, label="non re-entrant" ];
  31         s8 [ shape=ellipse, color="red", label="Error States" ];
  32
  33         s6->s7->s8->s1->s2->s3->s5->s4 [style="invis"];
  34
  35         }
  36
  37         node [ peripheries = "2" ] \
  38                 RELEASING ALLOC LOADING EXCLUSIVE STORE ;
  39         node [ shape = "ellipse", peripheries = "1" ];
  40         node [ color = "red" ] ERROR ;
  41
  42         node [ color = "black" ]; // default back to black
  43
  44
  45         // node descriptions
  46         INVALID [ label = "Vn_state(vnp) == VN_STATE_INVALID\n(vnode cache entry is invalid)" ];
  47         RELEASING [ label = "Vn_state(vnp) == VN_STATE_RELEASING\n(vnode is busy releasing its inode handle ref)" ];
  48         ALLOC [ label = "Vn_state(vnp) == VN_STATE_ALLOC\n(vnode is busy allocating disk entry)" ];
  49         ALLOC_read [ label = "reading stale vnode from disk\nto verify inactive state" ];
  50         ALLOC_extend [ label = "extending vnode index file" ];
  51         ONLINE [ label = "Vn_state(vnp) == VN_STATE_ONLINE\n(vnode is a valid cache entry)" ];
  52         LOADING [ label = "Vn_state(vnp) == VN_STATE_LOAD\n(vnode is busy loading from disk)" ];
  53         EXCLUSIVE [ label = "Vn_state(vnp) == VN_STATE_EXCLUSIVE\n(vnode is owned exclusively by an external caller)" ];
  54         STORE [ label = "Vn_state(vnp) == VN_STATE_STORE\n(vnode is busy writing to disk)" ];
  55         READ [ label = "Vn_state(vnp) == VN_STATE_READ\n(vnode is shared by several external callers)" ];
  56         ERROR [ label = "Vn_state(vnp) == VN_STATE_ERROR\n(vnode hard error state)" ];
  57
  58
  59         ONLINE->RELEASING [ label = "VGetFreeVnode_r()" ];
  60         RELEASING->INVALID [ label = "VGetFreeVnode_r()" ];
  61
  62         INVALID->ALLOC [ color="brown", label="vnode not in cache; allocating" ];
  63         ONLINE->EXCLUSIVE [ color="brown", label="vnode in cache" ];
  64         ALLOC->ALLOC_read [ color="brown", label="vnode index is within present file size" ];
  65         ALLOC->ALLOC_extend [ color="brown", label="vnode index is beyond end of file" ];
  66         ALLOC_read->EXCLUSIVE [ color="brown" ];
  67         ALLOC_extend->EXCLUSIVE [ color="brown" ];
  68         ALLOC_read->INVALID [ color="red", label="I/O error; invalidating vnode\nand scheduling salvage" ];
  69         ALLOC_extend->INVALID [ color="red", label="I/O error; invalidating vnode\nand scheduling salvage" ];
  70
  71         INVALID->LOADING [ color="blue", label="vnode not cached" ];
  72         LOADING->INVALID [ color="red", label="I/O error; invalidating vnode\nand scheduling salvage" ];
  73         LOADING->ONLINE [ color="blue" ];
  74         ONLINE->READ [ color="blue", label="caller requested read lock" ];
  75         ONLINE->EXCLUSIVE [ color="blue", label="caller requested write lock" ];
  76
  77         EXCLUSIVE->READ [ color="green", label="vnode not changed" ];
  78         EXCLUSIVE->STORE [ color="green", label="vnode changed" ];
  79         EXCLUSIVE->ONLINE [ color="purple", label="vnode not changed" ];
  80         EXCLUSIVE->STORE [ color="purple", label="vnode changed" ];
  81
  82         STORE->READ [ color="green" ];
  83         STORE->ONLINE [ color="purple" ];
  84         STORE->ERROR [ color="red", label="I/O error; scheduling salvage" ];
  85
  86         READ->READ [ color="blue", label="Vn_readers(vnp) > 0" ];
  87         READ->READ [ color="purple", label="Vn_readers(vnp) > 1" ];
  88         READ->ONLINE [ color="purple", label="Vn_readers(vnp) == 1" ];
  89 }