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: NFred Isaman <iisaman@netapp.com>
Signed-off-by: NBenny Halevy <bhalevy@panasas.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Signed-off-by: NFred Isaman <iisaman@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

While we are renaming all the fields, change lo->state to lo->plh_flags.
Signed-off-by: NFred Isaman <iisaman@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Comment references get_layout_hdr_locked, which never existed in
submitted code.
Signed-off-by: NFred Isaman <iisaman@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

The initialize_mountpoint/uninitialise_mountpoint functions are really about
setting or clearing the layout driver to be used on this filesystem. Change
the names to the more descriptive 'set_layoutdriver/clear_layoutdriver'.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Add the ability to actually send LAYOUTGET and GETDEVICEINFO.  This also adds
in the machinery to handle layout state and the deviceid cache.  Note that
GETDEVICEINFO is not called directly by the generic layer.  Instead it
is called by the drivers while parsing the LAYOUTGET opaque data in response
to an unknown device id embedded therein.  RFC 5661 only encodes
device ids within the driver-specific opaque data.
Signed-off-by: NAndy Adamson <andros@netapp.com>
Signed-off-by: NDean Hildebrand <dhildebz@umich.edu>
Signed-off-by: NMarc Eshel <eshel@almaden.ibm.com>
Signed-off-by: NMike Sager <sager@netapp.com>
Signed-off-by: NRicardo Labiaga <ricardo.labiaga@netapp.com>
Signed-off-by: NTao Guo <guotao@nrchpc.ac.cn>
Signed-off-by: NBoaz Harrosh <bharrosh@panasas.com>
Signed-off-by: NFred Isaman <iisaman@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

In particular, server reboot will invalidate all layouts.

Note that in order to have an active layout, we must get a successful response
from the server.  To avoid adding that machinery, this patch just includes a
stub that fakes up a successful return.  Since the layout is never referenced
for io, this is not a problem.
Signed-off-by: NAndy Adamson <andros@netapp.com>
Signed-off-by: NBenny Halevy <bhalevy@panasas.com>
Signed-off-by: NDean Hildebrand <dhildebz@umich.edu>
Signed-off-by: NFred Isaman <iisaman@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

At the start of the io paths, try to grab the relevant layout
information.  This will initiate the inode's layout cache, but
stubs ensure the cache stays empty.
Signed-off-by: NBenny Halevy <bhalevy@panasas.com>
Signed-off-by: NDean Hildebrand <dhildebz@umich.edu>
Signed-off-by: NMarc Eshel <eshel@almaden.ibm.com>
Signed-off-by: NTao Guo <guotao@nrchpc.ac.cn>
Signed-off-by: NRicardo Labiaga <ricardo.labiaga@netapp.com>
Signed-off-by: NBoaz Harrosh <bharrosh@panasas.com>
Signed-off-by: NAndy Adamson <andros@netapp.com>
Signed-off-by: NFred Isaman <iisaman@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Allow a module implementing a layout type to register, and
have its mount/umount routines called for filesystems that
the server declares support it.
Signed-off-by: NFred Isaman <iisaman@netapp.com>
Signed-off-by: NMarc Eshel <eshel@almaden.ibm.com>
Signed-off-by: Andy Adamson<andros@netapp.com>
Signed-off-by: NBian Naimeng <biannm@cn.fujitsu.com>
Signed-off-by: NBenny Halevy <bhalevy@panasas.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Put in the infrastructure that uses information returned from the
server at mount to select a layout driver module.

In this patch, a stub is used that always returns "no driver found".
Signed-off-by: NRicardo Labiaga <Ricardo.Labiaga@netapp.com>
Signed-off-by: NDean Hildebrand <dhildebz@umich.edu>
Signed-off-by: NMarc Eshel <eshel@almaden.ibm.com>
Signed-off-by: NAndy Adamson <andros@netapp.com>
Signed-off-by: NBenny Halevy <bhalevy@panasas.com>
Signed-off-by: NFred Isaman <iisaman@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>