NFSv4: Sanity check the parameters in nfs41_update_target_slotid()

Ensure that the values supplied by the server do not exceed the size of
the largest allowed slot table.

Reported-by: <rtm@csail.mit.edu>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

NFSv4.1: use BITS_PER_LONG macro in nfs4session.h

Use the existing BITS_PER_LONG macro instead of calculating the value.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

NFSv4.1: Bump the default callback session slot count to 16

Users can still control this value explicitly using the
max_session_cb_slots module parameter, but let's bump the default
up to 16 for now.

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

NFSv4.1: Avoid false retries when RPC calls are interrupted

A 'false retry' in NFSv4.1 occurs when the client attempts to transmit a
new RPC call using a slot+sequence number combination that references an
already cached one. Currently, the Linux NFS client will do this if a
user process interrupts an RPC call that is in progress.
The problem with doing so is that we defeat the main mechanism used by
the server to differentiate between a new call and a replayed one. Even
if the server is able to perfectly cache the arguments of the old call,
it cannot know if the client intended to replay or send a new call.

The obvious fix is to bump the sequence number pre-emptively if an
RPC call is interrupted, but in order to deal with the corner cases
where the interrupted call is not actually received and processed by
the server, we need to interpret the error NFS4ERR_SEQ_MISORDERED
as a sign that we need to either wait or locate a correct sequence
number that lies between the value we sent, and the last value that
was acked by a SEQUENCE call on that slot.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Tested-by: Jason Tibbitts <tibbs@math.uh.edu>

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

NFS: Make trace_nfs4_setup_sequence() available to NFS v4.0

This tracepoint displays information about the slot that was chosen for
the RPC, in addition to session information. This could be useful
information for debugging, and we can set the session id hash to 0 to
indicate that there is no session.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

NFS: Change nfs4_get_session() to take an nfs_client structure

pNFS only has access to the nfs_client structure, and not the
nfs_server, so we need to make this change so the function can be used
by pNFS as well.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

NFS: Move nfs4_get_session() into nfs4_session.h

This puts session related functions together in the same space. I only
keep one version of this function, since this variable will always be
NULL when using NFS v4.0.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

NFSv4.1: Don't deadlock the state manager on the SEQUENCE status flags

As described in RFC5661, section 18.46, some of the status flags exist
in order to tell the client when it needs to acknowledge the existence of
revoked state on the server and/or to recover state.
Those flags will then remain set until the recovery procedure is done.

In order to avoid looping, the client therefore needs to ignore
those particular flags while recovering.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Tested-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

NFSv4.x: Add kernel parameter to control the callback server

Add support for the kernel parameter nfs.callback_nr_threads to set
the number of threads that will be assigned to the callback channel.

Add support for the kernel parameter nfs.nfs.max_session_cb_slots
to set the maximum size of the callback channel slot table.

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

NFSv4.1: Defer bumping the slot sequence number until we free the slot

For operations like OPEN or LAYOUTGET, which return recallable state
(i.e. delegations and layouts) we want to enable the mechanism for
resolving recall races in RFC5661 Section 2.10.6.3.
To do so, we will want to defer bumping the slot's sequence number until
we have finished processing the RPC results.

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

NFSv4.1: Delay callback processing when there are referring triples

If CB_SEQUENCE tells us that the processing of this request depends on
the completion of one or more referring triples (see RFC 5661 Section
2.10.6.3), delay the callback processing until after the RPC requests
being referred to have completed.
If we end up delaying for more than 1/2 second, then fall back to
returning NFS4ERR_DELAY in reply to the callback.

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

NFSv4.1: Fix Oopsable condition in server callback races

The slot table hasn't been an array since v3.7. Ensure that we
use nfs4_lookup_slot() to access the slot correctly.

Fixes: 87dda67e7386 ("NFSv4.1: Allow SEQUENCE to resize the slot table...")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: stable@vger.kernel.org # v3.8+

NFSv4.x: Allow multiple callbacks in flight

Hook the callback channel into the same session management machinery
as we use for the forward channel.

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

NFSv4.1: Clear the old state by our client id before establishing a new lease

If the call to exchange-id returns with the EXCHGID4_FLAG_CONFIRMED_R flag
set, then that means our lease was established by a previous mount instance.
Ensure that we detect this situation, and that we clear the state held by
that mount.

Reported-by: Jorge Mora <Jorge.Mora@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

NFSv4.1: Clean up create_session

Don't decode directly into the shared struct session

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

NFSv4.1: nfs4_destroy_session must call rpc_destroy_waitqueue

There may still be timers active on the session waitqueues. Make sure
that we kill them before freeing the memory.

Cc: stable@vger.kernel.org # 3.12+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

When CONFIG_NFS_V4_1 is not enabled, "make C=2" emits this warning:

linux/fs/nfs/nfs4session.c:337:6: warning:
symbol 'nfs41_set_target_slotid' was not declared. Should it be static?

Move nfs41_set_target_slotid() and nfs41_update_target_slotid() back
behind CONFIG_NFS_V4_1, since, in the final revision of this work,
they are used only in NFSv4.1 and later.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

NFS: Add global helper for releasing slot table resources

The nfs4_destroy_slot_tables() function is renamed to avoid
confusion with the new helper.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

NFS: Add global helper to set up a stand-along nfs4_slot_table

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

NFS: Enable slot table helpers for NFSv4.0

I'd like to re-use NFSv4.1's slot table machinery for NFSv4.0
transport blocking. Re-organize some of nfs4session.c so the slot
table code is built even when NFS_V4_1 is disabled.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

NFSv4.1: Add tracepoints for debugging slot table operations

Add tracepoints to nfs41_setup_sequence and nfs41_sequence_done
to track session and slot table state changes.

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

NFSv4.1 Increase NFS4_DEF_SLOT_TABLE_SIZE

Increase NFS4_DEF_SLOT_TABLE_SIZE which is used as the client ca_maxreequests
value in CREATE_SESSION. Current non-dynamic session slot server
implementations use the client ca_maxrequests as a maximum slot number: 64
session slots can handle most workloads.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

NFSv4.1 Refactor nfs4_init_session and nfs4_init_channel_attrs

nfs4_init_session was originally written to be called prior to
nfs4_init_channel_attrs, setting the session target_max response and request
sizes that nfs4_init_channel_attrs would pay attention to.

In the current code flow, nfs4_init_session, just like nfs4_init_ds_session
for the data server case, is called after the session is all negotiated, and
is actually used in a RECLAIM COMPLETE call to the server.

Remove the un-needed fc_target_max response and request fields from
nfs4_session and just set the max_resp_sz and max_rqst_sz in
nfs4_init_channel_attrs.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

NFSv4.1 Fix a pNFS session draining deadlock

On a CB_RECALL the callback service thread flushes the inode using
filemap_flush prior to scheduling the state manager thread to return the
delegation. When pNFS is used and I/O has not yet gone to the data server
servicing the inode, a LAYOUTGET can preceed the I/O. Unlike the async
filemap_flush call, the LAYOUTGET must proceed to completion.

If the state manager starts to recover data while the inode flush is sending
the LAYOUTGET, a deadlock occurs as the callback service thread holds the
single callback session slot until the flushing is done which blocks the state
manager thread, and the state manager thread has set the session draining bit
which puts the inode flush LAYOUTGET RPC to sleep on the forechannel slot
table waitq.

Separate the draining of the back channel from the draining of the fore channel
by moving the NFS4_SESSION_DRAINING bit from session scope into the fore
and back slot tables. Drain the back channel first allowing the LAYOUTGET
call to proceed (and fail) so the callback service thread frees the callback
slot. Then proceed with draining the forechannel.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

NFSv4.1: Deal effectively with interrupted RPC calls.

If an RPC call is interrupted, assume that the server hasn't processed
the RPC call so that the next time we use the slot, we know that if we
get a NFS4ERR_SEQ_MISORDERED or NFS4ERR_SEQ_FALSE_RETRY, we just have
to bump the sequence number.

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

NFSv4.1: Move the RPC timestamp out of the slot.

Shave a few bytes off the slot table size by moving the RPC timestamp
into the sequence results.

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

NFSv4.1: Try to eliminate outliers when updating target_highest_slotid

Look for sudden changes in the first and second derivatives in order
to eliminate outlier changes to target_highest_slotid (which are
due to out-of-order RPC replies).

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

NFSv4.1: Ensure smooth handover of slots from one task to the next waiting

Currently, we see a lot of bouncing for the value of highest_used_slotid
due to the fact that slots are getting freed, instead of getting instantly
transmitted to the next waiting task.

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

NFSv4.1: Set the maximum slot table size to 1024 slots

This means that we end up statically allocating 128 bytes for the
bitmap on each slot table.
For a server that supports 1MB write and read I/O sizes this means
that we can completely fill the maximum 1GB TCP send/receive
windows.

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

NFSv4.1: Move slot table and session struct definitions to nfs4session.h

Clean up. Gather NFSv4.1 slot definitions in fs/nfs/nfs4session.h.

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

NFSv4.1: Cleanup move session slot management to fs/nfs/nfs4session.c

NFSv4.1 session management is getting complex enough to deserve
a separate file.

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