It's possible and acceptable for NFS to attempt to add requests beyond the
range of the current pgio->pg_lseg, a case which should be caught and
limited by the pg_test operation.  However, the current handling of this
case replaces pgio->pg_lseg with a new layout segment (after a WARN) within
that pg_test operation.  That will cause all the previously added requests
to be submitted with this new layout segment, which may not be valid for
those requests.

Fix this problem by only returning zero for the number of bytes to coalesce
from pg_test for this case which allows any previously added requests to
complete on the current layout segment.  The check for requests starting
out of range of the layout segment moves to pg_init, so that the
replacement of pgio->pg_lseg will be done when the next request is added.
Signed-off-by: NBenjamin Coddington <bcodding@redhat.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Consider the following deadlock:

Process P1	Process P2		Process P3
==========	==========		==========
					lock_page(page)

		lseg = pnfs_update_layout(inode)

lo = NFS_I(inode)->layout
pnfs_error_mark_layout_for_return(lo)

		lock_page(page)

					lseg = pnfs_update_layout(inode)

In this scenario,
- P1 has declared the layout to be in error, but P2 holds a reference to
  a layout segment on that inode, so the layoutreturn is deferred.
- P2 is waiting for a page lock held by P3.
- P3 is asking for a new layout segment, but is blocked waiting
  for the layoutreturn.

The fix is to ensure that pnfs_error_mark_layout_for_return() does
not set the NFS_LAYOUT_RETURN flag, which blocks P3. Instead, we allow
the latter to call LAYOUTGET so that it can make progress and unblock
P2.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

In pnfs_clear_layoutreturn_info, ensure that we don't clear the layout
return info if there are new segments queued for return due to, for
instance, a race between a LAYOUTRETURN and a failed I/O attempt.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

If the layout is being invalidated on the server, then we must
invoke nfs_commit_inode() to ensure any commits to the DS get
cleared out.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

If the attempt to write through pNFS fails, we need to use the same
failure semantics as for the read path: If the FF_FLAGS_NO_IO_THRU_MDS
flag is set or we have sufficient valid DSes, then we must retry through
pNFS

Fixes: d67ae825 ("pnfs/flexfiles: Add the FlexFile Layout Driver")
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

pnfs_error_mark_layout_for_return needs to check that the layout is
valid before calling pnfs_set_plh_return_info().
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

The assumption should be that if the caller returns PNFS_ATTEMPTED, then hdr
has been consumed, and so we should not be testing hdr->task.tk_status.
If the caller returns PNFS_TRY_AGAIN, then we need to recoalesce and
free hdr.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

If we have a layout segment cached in pgio->pg_lseg, we should check it
for validity before reusing it in a new RPC request. Otherwise, if we
recoalesce, we can end up looping forever.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

They are not used outside the NFSv4 module.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

IF NFS_LAYOUT_RETURN_REQUESTED is not set, then we currently exit
without freeing the list of invalidated layout segments, leading
to a reference leak.
Reported-by: NOlga Kornievskaia <aglo@umich.edu>
Fixes: 24408f52 ("pNFS: Fix bugs in _pnfs_return_layout")
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

If the client holds no more writeable open state, and does not hold a
write delegation, then send a layoutreturn as part of the OPEN_DOWNGRADE.

We do this only for writes, since some layout drivers may require you to
also hold a read layout if you are doing a R/W workload.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Ensure we release the NFS_LAYOUT_RETURN lock when we invalidate the
layout stateid, so that processes and RPC tasks that are waiting on
the layout return can continue.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Add a callback to allow the flexfiles layout driver to initialise the
layout private payload.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Cleanup to allow layout drivers to attach private data to layoutreturn,
and manage the data.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

If the layout stateid is already invalid, we have no work to do.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Address another memory leak.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Ensure that the layout state bits are synced when we cache a layout
segment for layoutreturn using an appropriate call to
pnfs_set_plh_return_info.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

We need to honour the NFS_LAYOUT_RETURN_REQUESTED bit regardless of
whether or not there are layout segments pending.
Furthermore, we should ensure that we leave the plh_return_segs list
empty.

This patch fixes a memory leak of the layout segments on plh_return_segs.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

When the layout state is invalidated, then so is the layout segment
state, and hence we do need to clean up the state bits.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Amend the pnfs return on close helper functions to enable sending the
layoutreturn op in CLOSE/DELEGRETURN. This closes a potential race between
CLOSE/DELEGRETURN and parallel OPEN calls to the same file, and allows the
client and the server to agree on whether or not there is an outstanding
layout.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

The layoutreturn call will take care of invalidating the layout segments
once the call is successful.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

There is no change to the value of NFS_LAYOUT_RETURN, so we should
not be waking up the RPC call.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Fix a potential race with CB_LAYOUTRECALL in which the server recalls the
remaining layout segments while our LAYOUTRETURN is still in transit.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

We may want to process and transmit layout stat information for the
layout segments that are being returned, so we should defer freeing
them until after the layoutreturn has completed.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Both pnfs.c and the flexfiles code have their own versions of the
range intersection testing, and the "end_offset" helper.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

We must put the task to sleep while holding the inode->i_lock in order
to ensure atomicity with the test for NFS_LAYOUT_RETURN.

Fixes: 500d701f ("NFS41: make close wait for layoutreturn")
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

If there is an I/O error, we should not call LAYOUTGET until the
LAYOUTRETURN that reports the error is complete.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
Cc: stable@vger.kernel.org # v4.8+

If the server sends us a completely new stateid, and the client thinks
it already holds a layout, then force a retry of the LAYOUTGET after
invalidating the existing layout in order to avoid corruption due to
races.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

We must ensure that we don't schedule a layoutreturn if the layout stateid
has been marked as invalid.

Fixes: 2a59a041 ("pNFS: Fix pnfs_set_layout_stateid() to clear...")
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
Cc: stable@vger.kernel.org # v4.8+

If we no longer hold any layout segments, we're normally expected to
consider the layout stateid to be invalid. However we cannot assume this
if we're about to, or in the process of sending a layoutreturn.

Fixes: 334a8f37 ("pNFS: Don't forget the layout stateid if...")
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
Cc: stable@vger.kernel.org # v4.8+

We must not call nfs_pageio_init_read() on a new nfs_pageio_descriptor
while holding a reference to a layout segment, as that can deadlock
pnfs_update_layout().

Fixes: d67ae825 ("pnfs/flexfiles: Add the FlexFile Layout Driver")
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
Cc: stable@vger.kernel.org # v4.0+

We used to check for a valid layout type id before verifying pNFS flags
as an indicator for if we are using pNFS.  This changed in 3132e49e
with the introduction of multiple layout types, since now we are passing
an array of ids instead of just one.  Since then, users have been seeing
a KERN_ERR printk show up whenever mounting NFS v4 without pNFS.  This
patch restores the original behavior of exiting set_pnfs_layoutdriver()
early if we aren't using pNFS.

Fixes 3132e49e ("pnfs: track multiple layout types in fsinfo
structure")
Reviewed-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Fix the code so that we always mark the atime as invalid in nfs4_read_done().
Currently, the expectation appears to be that the pNFS drivers should always
do this, with the result that most of them don't.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Currently, the layout driver selection code always chooses the first one
from the list. That's not really ideal however, as the server can send
the list of layout types in any order that it likes. It's up to the
client to select the best one for its needs.

This patch adds an ordered list of preferred driver types and has the
selection code sort the list of available layout drivers according to it.
Any unrecognized layout type is sorted to the end of the list.

For now, the order of preference is hardcoded, but it should be possible
to make this configurable in the future.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Reviewed-by: NJ. Bruce Fields <bfields@fieldses.org>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

Current NFSv4.1/pNFS client assumes that MDS supports only one layout
type. While it's true for most existing servers, nevertheless, this can
be change in the near future.

For now, this patch just plumbs in the ability to track a list of
layouts in the fsinfo structure. The existing behavior of the client
is preserved, by having it just select the first entry in the list.
Signed-off-by: NTigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Signed-off-by: NJeff Layton <jlayton@poochiereds.net>
Reviewed-by: NJ. Bruce Fields <bfields@fieldses.org>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>

If there are outstanding LAYOUTGET rpc calls, then we want to ensure that
we keep the layout stateid around so we that don't inadvertently pick up
an old/misordered sequence id.
The race is as follows:

Client				Server
======				======
LAYOUTGET(seqid)
LAYOUTGET(seqid)
				return LAYOUTGET(seqid+1)
				return LAYOUTGET(seqid+2)
process LAYOUTGET(seqid+2)
	forget layout
process LAYOUTGET(seqid+1)

If it forgets the layout stateid before processing seqid+1, then
the client will not check the layout->plh_barrier, and so will set
the stateid with seqid+1.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

If the layout was marked as invalid, we want to ensure to initialise
the layout header fields correctly.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>