Signed-off-by: NPeng Tao <tao.peng@primarydata.com>
Signed-off-by: NTom Haynes <Thomas.Haynes@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

We need to hold cinfo lock while setting bucket->wlseg and adding req to nwritten
list at the same time. Otherwise there might be a window where nwritten list
is empty yet we set bucket->wlseg, in which case ff_layout_scan_ds_commit_list()
may end up clearing bucket->wlseg incorrectly, casuing client to oops later on.

This was found when testing flexfile layout but filelayout has the same problem.
Signed-off-by: NPeng Tao <tao.peng@primarydata.com>
Signed-off-by: NTom Haynes <Thomas.Haynes@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Clean up pnfs_read_done_resend_to_mds and pnfs_write_done_resend_to_mds:
 - instead of passing all arguments from a nfs_pgio_header, just pass the header
 - share the common code
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NWeston Andros Adamson <dros@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

struct nfs_pgio_data only exists as a member of nfs_pgio_header, but is
passed around everywhere, because there used to be multiple _data structs
per _header. Many of these functions then use the _data to find a pointer
to the _header.  This patch cleans this up by merging the nfs_pgio_data
structure into nfs_pgio_header and passing nfs_pgio_header around instead.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NWeston Andros Adamson <dros@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

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

The save of the write offset was removed some time ago, so that
part of the comment is bogus.

The remainder is pretty self-evident.

So off with it!
Signed-off-by: NTom Haynes <Thomas.Haynes@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

The object and block layouts already exist in their own
subdirectories. This patch completes the set!

Note that as a layout denotes nfs4 already, I stripped
that prefix out of the file names.
Signed-off-by: NTom Haynes <Thomas.Haynes@primarydata.com>
Acked-by: NJeff Layton <jlayton@poochiereds.net>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Return the NULL pointer when the allocation fails.
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Cc: <stable@vger.kernel.org> # 3.5.x
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Use the new pg_test interface to adjust requests to fit in the current
stripe / segment.
Signed-off-by: NWeston Andros Adamson <dros@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Support direct requests that span multiple pnfs data servers by
comparing nfs_pgio_header->verf to a cached verf in pnfs_commit_bucket.
Continue to use dreq->verf if the MDS is used / non-pNFS.
Signed-off-by: NWeston Andros Adamson <dros@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Now that pg_test can change the size of the request (by returning a non-zero
size smaller than the request), pg_test functions that call other
pg_test functions must return the minimum of the result - or 0 if any fail.

Also clean up the logic of some pg_test functions so that all checks are
for contitions where coalescing is not possible.
Signed-off-by: NWeston Andros Adamson <dros@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Remove unneeded else statement and clean up how commit info
dataserver buckets are replaced.
Suggested-by: NTrond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: NWeston Andros Adamson <dros@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Call nfs_can_coalesce_requests for every request, even the first one.
This is needed for future patches to give pg_test a way to inform
add_request to reduce the size of the request.

Now @prev can be null in nfs_can_coalesce_requests and pg_test functions.
Signed-off-by: NWeston Andros Adamson <dros@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

This is a step toward allowing pg_test to inform the the
coalescing code to reduce the size of requests so they may fit in
whatever scheme the pg_test callback wants to define.

For now, just return the size of the request if there is space, or 0
if there is not.  This shouldn't change any behavior as it acts
the same as when the pg_test functions returned bool.
Signed-off-by: NWeston Andros Adamson <dros@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Hold the lock while modifying commit info dataserver buckets.

The following oops can be reproduced by running iozone for a while against
a 2 DS pynfs filelayout server.

general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC
Modules linked in: nfs_layout_nfsv41_files rpcsec_gss_krb5 nfsv4 nfs fscache
CPU: 0 PID: 903 Comm: iozone Not tainted 3.15.0-rc1-branch-dros_testing+ #44
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference
task: ffff880078164480 ti: ffff88006e972000 task.ti: ffff88006e972000
RIP: 0010:[<ffffffffa01936e1>]  [<ffffffffa01936e1>] nfs_init_commit+0x22/0x
RSP: 0018:ffff88006e973d30  EFLAGS: 00010246
RAX: ffff88006e973e00 RBX: ffff88006e828800 RCX: ffff88006e973e10
RDX: 0000000000000000 RSI: ffff88006e973e00 RDI: dead4ead00000000
RBP: ffff88006e973d38 R08: ffff88006e8289d8 R09: 0000000000000000
R10: ffff88006e8289d8 R11: 0000000000016988 R12: ffff88006e973b98
R13: ffff88007a0a6648 R14: ffff88006e973e10 R15: ffff88006e828800
FS:  00007f2ce396b740(0000) GS:ffff88007f200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f03278a1000 CR3: 0000000079043000 CR4: 00000000001407f0
Stack:
ffff88006e8289d8 ffff88006e973da8 ffffffffa00f144f ffff88006e9478c0
ffff88006e973e00 ffff88006de21080 0000000100000002 ffff880079be6c48
ffff88006e973d70 ffff88006e973d70 ffff88006e973e10 ffff88006de21080
Call Trace:
[<ffffffffa00f144f>] filelayout_commit_pagelist+0x1ae/0x34a [nfs_layout_nfsv
[<ffffffffa0194f72>] nfs_generic_commit_list+0x92/0xc4 [nfs]
[<ffffffffa0195053>] nfs_commit_inode+0xaf/0x114 [nfs]
[<ffffffffa01892bd>] nfs_file_fsync_commit+0x82/0xbe [nfs]
[<ffffffffa01ceb0d>] nfs4_file_fsync+0x59/0x9b [nfsv4]
[<ffffffff8114ee3c>] vfs_fsync_range+0x18/0x20
[<ffffffff8114ee60>] vfs_fsync+0x1c/0x1e
[<ffffffffa01891c2>] nfs_file_flush+0x7f/0x84 [nfs]
[<ffffffff81127a43>] filp_close+0x3c/0x72
[<ffffffff81140e12>] __close_fd+0x82/0x9a
[<ffffffff81127a9c>] SyS_close+0x23/0x4c
[<ffffffff814acd12>] system_call_fastpath+0x16/0x1b
Code: 5b 41 5c 41 5d 41 5e 5d c3 0f 1f 44 00 00 55 48 89 e5 53 48 89 fb 48 8
RIP  [<ffffffffa01936e1>] nfs_init_commit+0x22/0xe1 [nfs]
RSP <ffff88006e973d30>
---[ end trace 732fe6419b235e2f ]---
Suggested-by: NTrond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: NWeston Andros Adamson <dros@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Most of this code is the same for both the read and write paths, so
combine everything and use the rw_ops when necessary.
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

At this point, the only difference between nfs_read_data and
nfs_write_data is the write verifier.
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Signed-off-by: NAndy Adamson <andros@netapp.com>
Link: http://lkml.kernel.org/r/1393954269-3974-1-git-send-email-andros@netapp.comSigned-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

It is now completely safe to call nfs41_sequence_free_slot with a NULL
slot.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Fix a dynamic session slot leak where a slot is preallocated and I/O is
resent through the MDS.
Signed-off-by: NAndy Adamson <andros@netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

cond_resched_lock(cinfo->lock) is called everywhere else while holding
the cinfo->lock spinlock.  Not holding this lock while calling
transfer_commit_list in filelayout_recover_commit_reqs causes the BUG
below.

It's true that we can't hold this lock while calling pnfs_put_lseg,
because that might try to lock the inode lock - which might be the
same lock as cinfo->lock.

To reproduce, mount a 2 DS pynfs server and run an O_DIRECT command
that crosses a stripe boundary and is not page aligned, such as:

 dd if=/dev/zero of=/mnt/f bs=17000 count=1 oflag=direct

BUG: sleeping function called from invalid context at linux/fs/nfs/nfs4filelayout.c:1161
in_atomic(): 0, irqs_disabled(): 0, pid: 27, name: kworker/0:1
2 locks held by kworker/0:1/27:
 #0:  (events){.+.+.+}, at: [<ffffffff810501d7>] process_one_work+0x175/0x3a5
 #1:  ((&dreq->work)){+.+...}, at: [<ffffffff810501d7>] process_one_work+0x175/0x3a5
CPU: 0 PID: 27 Comm: kworker/0:1 Not tainted 3.13.0-rc3-branch-dros_testing+ #21
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/31/2013
Workqueue: events nfs_direct_write_schedule_work [nfs]
 0000000000000000 ffff88007a39bbb8 ffffffff81491256 ffff88007b87a130  ffff88007a39bbd8 ffffffff8105f103 ffff880079614000 ffff880079617d40  ffff88007a39bc20 ffffffffa011603e ffff880078988b98 0000000000000000
Call Trace:
 [<ffffffff81491256>] dump_stack+0x4d/0x66
 [<ffffffff8105f103>] __might_sleep+0x100/0x105
 [<ffffffffa011603e>] transfer_commit_list+0x94/0xf1 [nfs_layout_nfsv41_files]
 [<ffffffffa01160d6>] filelayout_recover_commit_reqs+0x3b/0x68 [nfs_layout_nfsv41_files]
 [<ffffffffa00ba53a>] nfs_direct_write_reschedule+0x9f/0x1d6 [nfs]
 [<ffffffff810705df>] ? mark_lock+0x1df/0x224
 [<ffffffff8106e617>] ? trace_hardirqs_off_caller+0x37/0xa4
 [<ffffffff8106e691>] ? trace_hardirqs_off+0xd/0xf
 [<ffffffffa00ba8f8>] nfs_direct_write_schedule_work+0x9d/0xb7 [nfs]
 [<ffffffff810501d7>] ? process_one_work+0x175/0x3a5
 [<ffffffff81050258>] process_one_work+0x1f6/0x3a5
 [<ffffffff810501d7>] ? process_one_work+0x175/0x3a5
 [<ffffffff8105187e>] worker_thread+0x149/0x1f5
 [<ffffffff81051735>] ? rescuer_thread+0x28d/0x28d
 [<ffffffff81056d74>] kthread+0xd2/0xda
 [<ffffffff81056ca2>] ? __kthread_parkme+0x61/0x61
 [<ffffffff8149e66c>] ret_from_fork+0x7c/0xb0
 [<ffffffff81056ca2>] ? __kthread_parkme+0x61/0x61
Signed-off-by: NWeston Andros Adamson <dros@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

A fileid in NFS is a uint64. There are some occurrences where dprintk()
outputs a signed fileid. This leads to confusion and more difficult to
read debugging (negative fileids matching positive inode numbers).
Signed-off-by: NNiels de Vos <ndevos@redhat.com>
CC: Santosh Pradhan <spradhan@redhat.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Commit 4edaa308 "NFS: Use "krb5i" to establish NFSv4 state whenever possible"
uses the nfs_client cl_rpcclient for all state management operations, and
will use krb5i or auth_sys with no regard to the mount command authflavor
choice.

The MDS, as any NFSv4.1 mount point, uses the nfs_server rpc client for all
non-state management operations with a different nfs_server for each fsid
encountered traversing the mount point, each with a potentially different
auth flavor.

pNFS data servers are not mounted in the normal sense as there is no associated
nfs_server structure. Data servers can also export multiple fsids, each with
a potentially different auth flavor.

Data servers need to use the same authflavor as the MDS server rpc client for
non-state management operations. Populate a list of rpc clients with the MDS
server rpc client auth flavor for the DS to use.
Signed-off-by: NAndy Adamson <andros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Set up tracepoints to track read, write and commit, as well as
pNFS reads and writes and commits to the data server.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

This is not strictly needed, since get_deviceinfo is not allowed to
return NFS4ERR_ACCESS or NFS4ERR_WRONG_CRED, but lets do it anyway
for consistency with other pNFS operations.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

If we replay a READ or WRITE call, we should not be changing the
stateid. Currently, we may end up doing so, because the stateid
is only selected at xdr encode time.

This patch ensures that we select the stateid after we get an NFSv4.1
session slot, and that we keep that same stateid across retries.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

If the state recovery failed, we want to ensure that the application
doesn't try to use the same file descriptor for more reads or writes.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

If state recovery fails with an ESTALE or a ENOENT, then we shouldn't
keep retrying. Instead, mark the stateid as being invalid and
fail the I/O with an EIO error.
For other operations such as POSIX and BSD file locking, truncate
etc, fail with an EBADF to indicate that this file descriptor is no
longer valid.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Note that clearing NFS_INO_LAYOUTCOMMIT is tricky, since it requires
you to also clear the NFS_LSEG_LAYOUTCOMMIT bits from the layout
segments.
The only two sites that need to do this are the ones that call
pnfs_return_layout() without first doing a layout commit.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: NBenny Halevy <bhalevy@tonian.com>
Cc: stable@vger.kernel.org

Pass the directio request on pageio_init to clean up the API.

Percolate pg_dreq from original nfs_pageio_descriptor to the
pnfs_{read,write}_done_resend_to_mds and use it on respective
call to nfs_pageio_init_{read,write} on the newly created
nfs_pageio_descriptor.

Reproduced by command:
 mount -o vers=4.1 server:/ /mnt
 dd bs=128k count=8 if=/dev/zero of=/mnt/dd.out oflag=direct

BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
IP: [<ffffffffa021a3a8>] atomic_inc+0x4/0x9 [nfs]
PGD 34786067 PUD 34794067 PMD 0
Oops: 0002 [#1] SMP
Modules linked in: nfs_layout_nfsv41_files nfsv4 nfs nfsd lockd nfs_acl auth_rpcgss exportfs sunrpc btrfs zlib_deflate libcrc32c ipv6 autofs4
CPU 1
Pid: 259, comm: kworker/1:2 Not tainted 3.8.0-rc6 #2 Bochs Bochs
RIP: 0010:[<ffffffffa021a3a8>]  [<ffffffffa021a3a8>] atomic_inc+0x4/0x9 [nfs]
RSP: 0018:ffff880038f8fa68  EFLAGS: 00010206
RAX: ffffffffa021a6a9 RBX: ffff880038f8fb48 RCX: 00000000000a0000
RDX: ffffffffa021e616 RSI: ffff8800385e9a40 RDI: 0000000000000028
RBP: ffff880038f8fa68 R08: ffffffff81ad6720 R09: ffff8800385e9510
R10: ffffffffa0228450 R11: ffff880038e87418 R12: ffff8800385e9a40
R13: ffff8800385e9a70 R14: ffff880038f8fb38 R15: ffffffffa0148878
FS:  0000000000000000(0000) GS:ffff88003e400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000028 CR3: 0000000034789000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process kworker/1:2 (pid: 259, threadinfo ffff880038f8e000, task ffff880038302480)
Stack:
 ffff880038f8fa78 ffffffffa021a6bf ffff880038f8fa88 ffffffffa021bb82
 ffff880038f8fae8 ffffffffa021f454 ffff880038f8fae8 ffffffff8109689d
 ffff880038f8fab8 ffffffff00000006 0000000000000000 ffff880038f8fb48
Call Trace:
 [<ffffffffa021a6bf>] nfs_direct_pgio_init+0x16/0x18 [nfs]
 [<ffffffffa021bb82>] nfs_pgheader_init+0x6a/0x6c [nfs]
 [<ffffffffa021f454>] nfs_generic_pg_writepages+0x51/0xf8 [nfs]
 [<ffffffff8109689d>] ? mark_held_locks+0x71/0x99
 [<ffffffffa0148878>] ? rpc_release_resources_task+0x37/0x37 [sunrpc]
 [<ffffffffa021bc25>] nfs_pageio_doio+0x1a/0x43 [nfs]
 [<ffffffffa021be7c>] nfs_pageio_complete+0x16/0x2c [nfs]
 [<ffffffffa02608be>] pnfs_write_done_resend_to_mds+0x95/0xc5 [nfsv4]
 [<ffffffffa0148878>] ? rpc_release_resources_task+0x37/0x37 [sunrpc]
 [<ffffffffa028e27f>] filelayout_reset_write+0x8c/0x99 [nfs_layout_nfsv41_files]
 [<ffffffffa028e5f9>] filelayout_write_done_cb+0x4d/0xc1 [nfs_layout_nfsv41_files]
 [<ffffffffa024587a>] nfs4_write_done+0x36/0x49 [nfsv4]
 [<ffffffffa021f996>] nfs_writeback_done+0x53/0x1cc [nfs]
 [<ffffffffa021fb1d>] nfs_writeback_done_common+0xe/0x10 [nfs]
 [<ffffffffa028e03d>] filelayout_write_call_done+0x28/0x2a [nfs_layout_nfsv41_files]
 [<ffffffffa01488a1>] rpc_exit_task+0x29/0x87 [sunrpc]
 [<ffffffffa014a0c9>] __rpc_execute+0x11d/0x3cc [sunrpc]
 [<ffffffff810969dc>] ? trace_hardirqs_on_caller+0x117/0x173
 [<ffffffffa014a39f>] rpc_async_schedule+0x27/0x32 [sunrpc]
 [<ffffffffa014a378>] ? __rpc_execute+0x3cc/0x3cc [sunrpc]
 [<ffffffff8105f8c1>] process_one_work+0x226/0x422
 [<ffffffff8105f7f4>] ? process_one_work+0x159/0x422
 [<ffffffff81094757>] ? lock_acquired+0x210/0x249
 [<ffffffffa014a378>] ? __rpc_execute+0x3cc/0x3cc [sunrpc]
 [<ffffffff810600d8>] worker_thread+0x126/0x1c4
 [<ffffffff8105ffb2>] ? manage_workers+0x240/0x240
 [<ffffffff81064ef8>] kthread+0xb1/0xb9
 [<ffffffff81064e47>] ? __kthread_parkme+0x65/0x65
 [<ffffffff815206ec>] ret_from_fork+0x7c/0xb0
 [<ffffffff81064e47>] ? __kthread_parkme+0x65/0x65
Code: 00 83 38 02 74 12 48 81 4b 50 00 00 01 00 c7 83 60 07 00 00 01 00 00 00 48 89 df e8 55 fe ff ff 5b 41 5c 5d c3 66 90 55 48 89 e5 <f0> ff 07 5d c3 55 48 89 e5 f0 ff 0f 0f 94 c0 84 c0 0f 95 c0 0f
RIP  [<ffffffffa021a3a8>] atomic_inc+0x4/0x9 [nfs]
 RSP <ffff880038f8fa68>
CR2: 0000000000000028
Signed-off-by: NBenny Halevy <bhalevy@tonian.com>
Cc: stable@kernel.org [>= 3.6]
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Currently, when an RPCSEC_GSS context has expired or is non-existent
and the users (Kerberos) credentials have also expired or are non-existent,
the client receives the -EKEYEXPIRED error and tries to refresh the context
forever.  If an application is performing I/O, or other work against the share,
the application hangs, and the user is not prompted to refresh/establish their
credentials. This can result in a denial of service for other users.

Users are expected to manage their Kerberos credential lifetimes to mitigate
this issue.

Move the -EKEYEXPIRED handling into the RPC layer. Try tk_cred_retry number
of times to refresh the gss_context, and then return -EACCES to the application.
Signed-off-by: NAndy Adamson <andros@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Nobody calls nfs4_setup_sequence or nfs41_setup_sequence without
also calling rpc_call_start() on success. This commit therefore
folds the rpc_call_start call into nfs41_setup_sequence().
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Clean up. Gather NFSv4.1 slot definitions in fs/nfs/nfs4session.h.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

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

Don't circumvent the array size checks.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Move the call to pnfs_return_layout() to the read and write rpc_release()
callbacks, so that it gets called from nfsiod, which is a more appropriate
context.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

There is nothing to prevent another thread from dereferencing ds->ds_clp
during or after the call to nfs4_ds_disconnect(), and Oopsing due to the
resulting NULL pointer.

Instead, we should just rely on filelayout_mark_devid_invalid() to keep
us out of trouble by avoiding that deviceid.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

We already have a mechanism for blocking LAYOUTGET by means of the
plh_block_lgets counter. The only "service" that NFS_LAYOUT_DESTROYED
provides at this point is to block layoutget once the layout segment
list is empty, which basically means that you have to wait until
the pnfs_layout_hdr is destroyed before you can do pNFS on that file
again.

This patch enables the reuse of the pnfs_layout_hdr if the layout
segment list is empty.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

In all cases where we set NFS_LAYOUT_INVALID, we also set NFS_LAYOUT_DESTROYED.
Furthermore, in all cases where we test for NFS_LAYOUT_INVALID, we should
also be testing for NFS_LAYOUT_DESTROYED, since the latter means that
we hold no valid layout segments.
Ergo the two are redundant.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

In cases where the pNFS data server is just temporarily out of service,
we want to mark it as such, and then try again later. Typically that will
be in cases of network connection errors etc.
This patch allows us to mark the devices as being "unavailable" for such
transient errors, and will make them available for retries after a
2 minute timeout period.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>