openafs/doc/txt/dafs-vnode-fsa.dot
Michael Meffie c6f5ebc4cf doc: relocate notes from arch to txt
The doc/txt directory has become the de facto home for text-based
technical notes. Relocate the contents of the doc/arch directory to
doc/txt. Relocate doc/examples to doc/txt/examples.

Update the doc/README file to be more current and remove old work in
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Change-Id: Iaa53e77eb1f7019d22af8380fa147305ac79d055
Reviewed-on: https://gerrit.openafs.org/12675
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
2017-08-03 20:44:28 -04:00

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#
# 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" ];
}