pnfs: change layout state seqlock to a spinlock
This prepares for future changes, where the layout state needs
to change atomically with several other variables. In particular,
it will need to know if lo->segs is empty, as we test that instead
of manipulating the NFS_LAYOUT_STATEID_SET bit. Moreover, the
layoutstateid is not really a read-mostly structure, as it is
written almost as often as it is read.
The behavior of pnfs_get_layout_stateid is also slightly changed, so that
it no longer changes the stateid. Its name is changed to +pnfs_choose_layoutget_stateid.
Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
3 files changed