ceph/branches/sage/cephmds2/doc/Commitdir.txt
sageweil c80eca7fce sage mds branch
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2007-01-19 19:48:59 +00:00

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How Directory Committing Works:
Each CDir has:
version - current version of directory
committing_version - which version was sent to stable storage
last_committed_version - last version to be safely stored
Each Inode has:
parent_dir_version - what dir version i was in when i was dirtied. (*)
(*) note that if you change an inode, mark_dirty() again, even if it's already dirty!
How committing works:
A call to commit_dir(dir, context) will ensure tha the _current_ version is stored safely on disk before the context is finished.
When a commit completes, inodes in the directory are checked. If they are dirty and belonged to the _committed_ (or earlier) version, then they are marked clean. If they belong to a newer version, then they are _still dirty_.