PNFS Implementation Issues

From Linux NFS

Revision as of 15:27, 2 April 2008

• NFSv4.1 Slot table implementation - Need to optimize the implementation for finding the lowest slot in the slot table implementation (nfs4_find_slot()).

• 2007/12/20 bhalevy: nfs4_setup_nfs4_program preps the global nfs_version4 structure. should be per server.

• 2008-04-02 bhalevy: Implement layout stateid as per draft-21+

• 2008-04-02 bhalevy: Implement pnfs-aware pags sync state model.

proposed model

Older Issues

• layoutget timing
  • a) If layoutget_on_open is set, the layout is sent in the same compound as OPEN
  • b) For reads, issue layoutget just before the read rpc is issued (using the offset and extent determined by the readahead code)
  • c) For write, add layoutget_post_write_coalesce and layoutget_pre_write_coalesce (or something)
    • Note 1: I think b and c need to happen in addition to a, since the server has the option of not returning a layout on open. Of course, b and c are only executed if the layout extent doesn't already exist in the layout cache.
    • Note 2: It seems we might need to add a note that says if you need to retrieve the boundary size from the server, then you must do (a) and/or layoutget_pre_write_coalesce=true.
    • Note 3: Use a single layout driver interface op to determine layoutget timing (takes in flag and returns a boolean)