NFS_LAYOUT_RETURN_BEFORE_CLOSE is being used to signal that a
layoutreturn is needed, either due to a layout recall or to a
layout error. Rename it to NFS_LAYOUT_RETURN_REQUESTED in order
to clarify its purpose.

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

* bugfixes:
  pNFS/flexfiles: Fix an XDR encoding bug in layoutreturn
  pNFS/flexfiles: Improve merging of errors in LAYOUTRETURN

When we hit 22 errors, we start to overflow the memory buffers allocated
to the LAYOUTRETURN errors. The issue is that currently, RPC call reply
ordering determines how successful we are in merging errors that refer
to contiguous READ or WRITE requests.

Fix is to use an insertion sort to help detect contiguity.

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

Fix a bug in which flexfiles clients are falling back to I/O through the
MDS even when the FF_FLAGS_NO_IO_THRU_MDS flag is set.

The flexfiles client will always report errors through the LAYOUTRETURN
and/or LAYOUTERROR mechanisms, so it should normally be safe for it
to retry the LAYOUTGET until it fails or succeeds.

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

If a read-write layout has an invalid mirror, then we should
mark it as invalid, and return it.
If a read-only layout has an invalid mirror, then mark it as invalid
and check if there is still at least one valid mirror before we return
it.

Note: Also fix incorrect use of pnfs_generic_mark_devid_invalid().
We really want nfs4_mark_deviceid_unavailable().

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

Unlike read layouts, the writeable layout cannot fall back to using only
one of the mirrors. It need to write to all of them.

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

Unlike the files layout, flexfiles does not test for the NFS_DEVICEID_INVALID
flag. Instead it relies on NFS_DEVICEID_UNAVAILABLE.
Fix is to replace with nfs4_mark_deviceid_unavailable().

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

According to the flexfiles protocol, the layoutreturn should specify an
array of errors in the following format:

struct ff_ioerr4 {
	offset4        ffie_offset;
	length4        ffie_length;
	stateid4       ffie_stateid;
	device_error4  ffie_errors<>;
};

This patch fixes up the code to ensure that our ffie_errors is indeed
encoded as an array (albeit with only a single entry).

Reported-by: Tom Haynes <thomas.haynes@primarydata.com>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

A ds can be associated with more than one mirror, but we currently skip
setting a mirror's credentials if we find that it's already set up with
a connected client.

The upshot is that we can end up sending DS writes with MDS credentials
instead of properly setting them up. Fix nfs4_ff_layout_prepare_ds to
always verify that the mirror's credentials are set up, even when we
have a DS that's already connected.

Reported-by: Tom Haynes <thomas.haynes@primarydata.com>
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Cc: stable@vger.kernel.org # 4.0+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

If we have two tasks racing to update a mirror's credentials, then they
can end up leaking one (or more) sets of credentials. The first task
will set mirror->cred and then the second task will just overwrite it.

Use a cmpxchg to ensure that the creds are only set once. If we get to
the point where we would set mirror->cred and find that they're already
set, then we just release the creds that were just found.

Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Cc: stable@vger.kernel.org # 4.0+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>