Move dm-bufio.h to include/linux/ so that external GPL'd DM target
modules can use it.

It is better to allow the use of dm-bufio than force external modules
to implement the equivalent buffered IO mechanism in some new way.  The
hope is this will encourage the use of dm-bufio; which will then make it
easier for a GPL'd external DM target module to be included upstream.

A couple dm-bufio EXPORT_SYMBOL exports have also been updated to use
EXPORT_SYMBOL_GPL.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

This comment was true when dm-bufio was written but, since 4.3, bios can
now have arbitrary size and the driver splits them.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Set QUEUE_FLAG_SECERASE in DM device's queue_flags if a DM table's
data devices support secure erase.

Also, add support for secure erase to both the linear and striped
targets.
Signed-off-by: Denis Semakin <d.semakin@omprussia.ru>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Otherwise, these abnormal IOs would be sent to the DM target
regardless of whether the target advertised support for them.

Factor out __process_abnormal_io() from __split_and_process_non_flush()
so that discards, write same, etc may be conditionally processed.

Fixes: 978e51ba ("dm: optimize bio-based NVMe IO submission")
Cc: stable@vger.kernel.org # 4.16
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Fix a race for "nosync" activations providing "aa.." device health
characters and "0/N" sync ratio rather than "AA..." and "N/N".  Occurs
when status for the raid set is retrieved during resume before the MD
sync thread starts and clears the MD_RECOVERY_NEEDED flag.

Cc: stable@vger.kernel.org # 4.16+
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Signed-off-by: Wang Sheng-Hui <shhuiw@foxmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Ideally, we'd like to get rid of all VLAs in the kernel and add -Wvla to
the build args: https://lkml.org/lkml/2018/3/7/621

This one is a simple case, since we don't actually need the VLA at all: we
can just iterate over the stripes twice, once to emit their names, and the
second time to emit status (i.e. trade memory for time). Since the number
of stripes is probably low, this is hopefully not that expensive.
Signed-off-by: Tycho Andersen <tycho@tycho.ws>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

So developer could distinguish data and metadata bios easier.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Since crypto API commit 9fa68f62 ("crypto: hash - prevent using keyed
hashes without setting key") dm-integrity cannot use keyed algorithms
without the key being set.

The dm-integrity recognizes this too late (during use of HMAC), so it
allows creation and formatting of superblock, but the device is in fact
unusable.

Fix it by detecting the key requirement in integrity table constructor.
Signed-off-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Signed-off-by: Wang Sheng-Hui <shhuiw@foxmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Reviewed-by: Scott Bauer <Scott.Bauer@intel.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

This target's kernel module being named dm-unstripe.ko doesn't allow
lvm2's DM module autoload capability to load the dm-unstripe.ko
because lvm2 looks for dm-unstriped.ko due to the target name being
"unstriped".

Add the "dm-unstriped" module alias to resolve this oversight.

NOTE: this isn't needed for the "striped" target, despite its source
file being named dm-stripe.c, because it is part of dm-mod.ko.
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Address "FIXME: must support non power of 2 chunk_size, dm-stripe.c does".

Bump target version to indicate change.
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Tested-by: Scott Bauer <Scott.Bauer@intel.com>
Reviewed-by: Scott Bauer <Scott.Bauer@intel.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

dm-crypt consumes an excessive amount memory when the user attempts to
zero a dm-crypt device with "blkdiscard -z". The command "blkdiscard -z"
calls the BLKZEROOUT ioctl, it goes to the function __blkdev_issue_zeroout,
__blkdev_issue_zeroout sends a large amount of write bios that contain
the zero page as their payload.

For each incoming page, dm-crypt allocates another page that holds the
encrypted data, so when processing "blkdiscard -z", dm-crypt tries to
allocate the amount of memory that is equal to the size of the device.
This can trigger OOM killer or cause system crash.

Fix this by limiting the amount of memory that dm-crypt allocates to 2%
of total system memory. This limit is system-wide and is divided by the
number of active dm-crypt devices and each device receives an equal
share.

Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Could be useful for a target to return stats or other information.
If a target does DMEMIT() anything to @result from its .message method
then it must return 1 to the caller.
Signed-off-By: Mike Snitzer <snitzer@redhat.com>

dm_get_bdev_for_ioctl()'s return of 0 or 1 must be the result from
prepare_ioctl (1 means the ioctl was issued to a partition, 0 means it
wasn't).  Unfortunately commit 519049af ("dm: use blkdev_get rather
than bdgrab when issuing pass-through ioctl") reused the variable 'r'
to store the return from blkdev_get() that follows prepare_ioctl()
-- whereby dropping prepare_ioctl()'s result on the floor.

This can lead to an ioctl or persistent reservation being issued to a
partition going unnoticed, which implies the extra permission check for
CAP_SYS_RAWIO is skipped.

Fix this by using a different variable to store blkdev_get()'s return.

Fixes: 519049af ("dm: use blkdev_get rather than bdgrab when issuing pass-through ioctl")
Reported-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

The ability to have multipath dynamically attach a scsi_dh, that the user
specified in the multipath table, was broken by commit e8f74a0f ("dm
mpath: eliminate need to use scsi_device_from_queue").

Restore the ability to load, and attach, a particular scsi_dh module if
one is specified (as noticed by checking m->hw_handler_name).

Fixes: e8f74a0f ("dm mpath: eliminate need to use scsi_device_from_queue")
Reported-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

After v4.12 commit e2460f2a ("dm: mark targets that pass integrity
data"), dm-multipath, e.g. on DIF+DIX SCSI disk paths, does not support
block integrity any more. So add it to the whitelist.

This is also a pre-requisite to use block integrity with other dm layer(s)
on top of multipath, such as kpartx partitions (dm-linear) or LVM.

Also, bump target version to reflect this fix.

Fixes: e2460f2a ("dm: mark targets that pass integrity data")
Cc: <stable@vger.kernel.org> #4.12+
Bisected-by: Fedor Loshakov <loshakov@linux.vnet.ibm.com>
Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Instead of scsi_device_from_queue(), use scsi_dh_attached_handler_name()
-- whose implementation uses scsi_device_from_queue() to avoid trying to
access SCSI-specific resources from non-SCSI devices.

Fixes buildbot reported issue when CONFIG_SCSI isn't set:
 ERROR: "scsi_device_from_queue" [drivers/md/dm-multipath.ko] undefined!

Fixes: 8d47e659 ("dm mpath: remove unnecessary NVMe branching in favor of scsi_dh checks")
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Initialize all the scsi_dh related 'struct multipath' members regardless
of whether a scsi_dh is in use or not.

The subtle (and fragile) SCSI-assuming legacy code clearly needs further
decoupling from non-SCSI (and/or developer understanding).

Fixes: 8d47e659 ("dm mpath: remove unnecessary NVMe branching in favor of scsi_dh checks")
Reported-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Pull x86/pti updates from Thomas Gleixner:
 "Yet another pile of melted spectrum related updates:

   - Drop native vsyscall support finally as it causes more trouble than
     benefit.

   - Make microcode loading more robust. There were a few issues
     especially related to late loading which are now surfacing because
     late loading of the IB* microcodes addressing spectre issues has
     become more widely used.

   - Simplify and robustify the syscall handling in the entry code

   - Prevent kprobes on the entry trampoline code which lead to kernel
     crashes when the probe hits before CR3 is updated

   - Don't check microcode versions when running on hypervisors as they
     are considered as lying anyway.

   - Fix the 32bit objtool build and a coment typo"

* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/kprobes: Fix kernel crash when probing .entry_trampoline code
  x86/pti: Fix a comment typo
  x86/microcode: Synchronize late microcode loading
  x86/microcode: Request microcode on the BSP
  x86/microcode/intel: Look into the patch cache first
  x86/microcode: Do not upload microcode if CPUs are offline
  x86/microcode/intel: Writeback and invalidate caches before updating microcode
  x86/microcode/intel: Check microcode revision before updating sibling threads
  x86/microcode: Get rid of struct apply_microcode_ctx
  x86/spectre_v2: Don't check microcode versions when running under hypervisors
  x86/vsyscall/64: Drop "native" vsyscalls
  x86/entry/64/compat: Save one instruction in entry_INT80_compat()
  x86/entry: Do not special-case clone(2) in compat entry
  x86/syscalls: Use COMPAT_SYSCALL_DEFINEx() macros for x86-only compat syscalls
  x86/syscalls: Use proper syscall definition for sys_ioperm()
  x86/entry: Remove stale syscall prototype
  x86/syscalls/32: Simplify $entry == $compat entries
  objtool: Fix 32-bit build

Pull timer fix from Thomas Gleixner:
 "Just a single fix which adds a missing Kconfig dependency to avoid
  unmet dependency warnings"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  clocksource/atmel-st: Add 'depends on HAS_IOMEM' to fix unmet dependency

Pull RAS fixes from Thomas Gleixner:
 "Two small fixes for RAS/MCE:

   - Serialize sysfs changes to avoid concurrent modificaiton of
     underlying data

   - Add microcode revision to Machine Check records. This should have
     been there forever, but now with the broken microcode versions in
     the wild it has become important"

* 'ras-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/MCE: Serialize sysfs changes
  x86/MCE: Save microcode revision in machine check records

Pull perf updates from Thomas Gleixner:
 "Another set of perf updates:

   - Fix a Skylake Uncore event format declaration

   - Prevent perf pipe mode from crahsing which was caused by a missing
     buffer allocation

   - Make the perf top popup message which tells the user that it uses
     fallback mode on older kernels a debug message.

   - Make perf context rescheduling work correcctly

   - Robustify the jump error drawing in perf browser mode so it does
     not try to create references to NULL initialized offset entries

   - Make trigger_on() robust so it does not enable the trigger before
     everything is set up correctly to handle it

   - Make perf auxtrace respect the --no-itrace option so it does not
     try to queue AUX data for decoding.

   - Prevent having different number of field separators in CVS output
     lines when a counter is not supported.

   - Make the perf kallsyms man page usage behave like it does for all
     other perf commands.

   - Synchronize the kernel headers"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/core: Fix ctx_event_type in ctx_resched()
  perf tools: Fix trigger class trigger_on()
  perf auxtrace: Prevent decoding when --no-itrace
  perf stat: Fix CVS output format for non-supported counters
  tools headers: Sync x86's cpufeatures.h
  tools headers: Sync copy of kvm UAPI headers
  perf record: Fix crash in pipe mode
  perf annotate browser: Be more robust when drawing jump arrows
  perf top: Fix annoying fallback message on older kernels
  perf kallsyms: Fix the usage on the man page
  perf/x86/intel/uncore: Fix Skylake UPI event format

Pull locking fix from Thomas Gleixner:
 "rt_mutex_futex_unlock() grew a new irq-off call site, but the function
  assumes that its always called from irq enabled context.

  Use (un)lock_irqsafe() to handle the new call site correctly"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rtmutex: Make rt_mutex_futex_unlock() safe for irq-off callsites

Pull dmaengine fixes from Vinod Koul:
 "Two small fixes are for this cycle:

   - fix max_chunk_size for rcar-dmac for R-Car Gen3

   - fix clock resource of mv_xor_v2"

* tag 'dmaengine-fix-4.16-rc5' of git://git.infradead.org/users/vkoul/slave-dma:
  dmaengine: mv_xor_v2: Fix clock resource by adding a register clock
  dmaengine: rcar-dmac: fix max_chunk_size for R-Car Gen3

Pull GPIO fix from Linus Walleij:
 "This is a single GPIO fix for the v4.16 series affecting the Renesas
  driver, and fixes wakeup from external stuff"

* tag 'gpio-v4.16-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
  gpio: rcar: Use wakeup_path i.s.o. explicit clock handling

On the CP110 components which are present on the Armada 7K/8K SoC we need
to explicitly enable the clock for the registers. However it is not
needed for the AP8xx component, that's why this clock is optional.

With this patch both clock have now a name, but in order to be backward
compatible, the name of the first clock is not used. It allows to still
use this clock with a device tree using the old binding.
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

Merge tag 'kbuild-fixes-v4.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - make fixdep parse kconfig.h to fix missing rebuild

 - replace hyphens with underscores in builtin DTB label names

 - fix typos

* tag 'kbuild-fixes-v4.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kbuild: Handle builtin dtb file names containing hyphens
  scripts/bloat-o-meter: fix typos in help
  fixdep: do not ignore kconfig.h
  fixdep: remove some false CONFIG_ matches
  fixdep: remove stale references to uml-config.h

Pull watchdog fixes from Wim Van Sebroeck:

 - f71808e_wdt: Fix magic close handling

 - sbsa: 32-bit read fix for WCV

 - hpwdt: Remove legacy NMI sourcing

* tag 'linux-watchdog-4.16-fixes-2' of git://www.linux-watchdog.org/linux-watchdog:
  watchdog: hpwdt: Remove legacy NMI sourcing.
  watchdog: sbsa: use 32-bit read for WCV
  watchdog: f71808e_wdt: Fix magic close handling

Pull block fixes from Jens Axboe:

 - a xen-blkfront fix from Bhavesh with a multiqueue fix when
   detaching/re-attaching

 - a few important NVMe fixes, including a revert for a sysfs fix that
   caused some user space confusion

 - two bcache fixes by way of Michael Lyle

 - a loop regression fix, fixing an issue with lost writes on DAX.

* tag 'for-linus-20180309' of git://git.kernel.dk/linux-block:
  loop: Fix lost writes caused by missing flag
  nvme_fc: rework sqsize handling
  nvme-fabrics: Ignore nr_io_queues option for discovery controllers
  xen-blkfront: move negotiate_mq to cover all cases of new VBDs
  Revert "nvme: create 'slaves' and 'holders' entries for hidden controllers"
  bcache: don't attach backing with duplicate UUID
  bcache: fix crashes in duplicate cache device register
  nvme: pci: pass max vectors as num_possible_cpus() to pci_alloc_irq_vectors
  nvme-pci: Fix EEH failure on ppc

Merge tag 'for-4.16/dm-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper fixes from Mike Snitzer:

 - Fix an uninitialized variable false warning in dm bufio

 - Fix DM's passthrough ioctl support to be race free against an
   underlying device being removed.

 - Fix corner-case of DM raid resync reporting if/when the raid becomes
   degraded during resync; otherwise automated raid repair will fail.

 - A few DM multipath fixes to make non-SCSI optimizations, that were
   introduced during the 4.16 merge, useful for all non-SCSI devices,
   rather than narrowly define this non-SCSI mode in terms of "nvme".

   This allows the removal of "queue_mode nvme" that really didn't need
   to be introduced. Instead DM core will internalize whether
   nvme-specific IO submission optimizations are doable and DM multipath
   will only do SCSI-specific device handler operations if SCSI is in
   use.

* tag 'for-4.16/dm-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm table: allow upgrade from bio-based to specialized bio-based variant
  dm mpath: remove unnecessary NVMe branching in favor of scsi_dh checks
  dm table: fix "nvme" test
  dm raid: fix incorrect sync_ratio when degraded
  dm: use blkdev_get rather than bdgrab when issuing pass-through ioctl
  dm bufio: avoid false-positive Wmaybe-uninitialized warning

Pull rdma fixes from Doug Ledford:

 - Various driver bug fixes in mlx5, mlx4, bnxt_re and qedr, ranging
   from bugs under load to bad error case handling

 - There in one largish patch fixing the locking in bnxt_re to avoid a
   machine hard lock situation

 - A few core bugs on error paths

 - A patch to reduce stack usage in the new CQ API

 - One mlx5 regression introduced in this merge window

 - There were new syzkaller scripts written for the RDMA subsystem and
   we are fixing issues found by the bot

 - One of the commits (aa0de36a “RDMA/mlx5: Fix integer overflow
   while resizing CQ”) is missing part of the commit log message and one
   of the SOB lines. The original patch was from Leon Romanovsky, and a
   cut-n-paste separator in the commit message confused patchworks which
   then put the end of message separator in the wrong place in the
   downloaded patch, and I didn’t notice in time. The patch made it into
   the official branch, and the only way to fix it in-place was to
   rebase. Given the pain that a rebase causes, and the fact that the
   patch has relevant tags for stable and syzkaller, a revert of the
   munged patch and a reapplication of the original patch with the log
   message intact was done.

* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma: (25 commits)
  RDMA/mlx5: Fix integer overflow while resizing CQ
  Revert "RDMA/mlx5: Fix integer overflow while resizing CQ"
  RDMA/ucma: Check that user doesn't overflow QP state
  RDMA/mlx5: Fix integer overflow while resizing CQ
  RDMA/ucma: Limit possible option size
  IB/core: Fix possible crash to access NULL netdev
  RDMA/bnxt_re: Avoid Hard lockup during error CQE processing
  RDMA/core: Reduce poll batch for direct cq polling
  IB/mlx5: Fix an error code in __mlx5_ib_modify_qp()
  IB/mlx5: When not in dual port RoCE mode, use provided port as native
  IB/mlx4: Include GID type when deleting GIDs from HW table under RoCE
  IB/mlx4: Fix corruption of RoCEv2 IPv4 GIDs
  RDMA/qedr: Fix iWARP write and send with immediate
  RDMA/qedr: Fix kernel panic when running fio over NFSoRDMA
  RDMA/qedr: Fix iWARP connect with port mapper
  RDMA/qedr: Fix ipv6 destination address resolution
  IB/core : Add null pointer check in addr_resolve
  RDMA/bnxt_re: Fix the ib_reg failure cleanup
  RDMA/bnxt_re: Fix incorrect DB offset calculation
  RDMA/bnxt_re: Unconditionly fence non wire memory operations
  ...

Pull x86 platform driver fixes from Darren Hart:
 "Correct a module loading race condition between the DELL_SMBIOS
  backend modules and the first user by converting them to bool features
  of the DELL_SMBIOS driver. Fixup the resulting Kconfig dependency
  issue with DCDBAS"

* tag 'platform-drivers-x86-v4.16-6' of git://git.infradead.org/linux-platform-drivers-x86:
  platform/x86: dell-smbios: Resolve dependency error on DCDBAS
  platform/x86: Allow for SMBIOS backend defaults
  platform/x86: dell-smbios: Link all dell-smbios-* modules together
  platform/x86: dell-smbios: Rename dell-smbios source to dell-smbios-base
  platform/x86: dell-smbios: Correct some style warnings

Pull KVM fixes from Radim Krčmář:
 "PPC:

   - Fix guest time accounting in the host

   - Fix large-page backing for radix guests on POWER9

   - Fix HPT guests on POWER9 backed by 2M or 1G pages

   - Compile fixes for some configs and gcc versions

  s390:

   - Fix random memory corruption when running as guest2 (e.g. KVM in
     LPAR) and starting guest3 (e.g. nested KVM) with many CPUs

   - Export forgotten io interrupt delivery statistics counter"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: s390: fix memory overwrites when not using SCA entries
  KVM: PPC: Book3S HV: Fix guest time accounting with VIRT_CPU_ACCOUNTING_GEN
  KVM: PPC: Book3S HV: Fix VRMA initialization with 2MB or 1GB memory backing
  KVM: PPC: Book3S HV: Fix handling of large pages in radix page fault handler
  KVM: s390: provide io interrupt kvm_stat
  KVM: PPC: Book3S: Fix compile error that occurs with some gcc versions
  KVM: PPC: Fix compile error that occurs when CONFIG_ALTIVEC=n

Pull xen fix from Juergen Gross:
 "Just one fix for the correct error handling after a failed
  device_register()"

* tag 'for-linus-4.16a-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen: xenbus: use put_device() instead of kfree()

Pull arm64 fixes from Catalin Marinas:

 - The SMCCC firmware interface for the spectre variant 2 mitigation has
   been updated to allow the discovery of whether the CPU needs the
   workaround. This pull request relaxes the kernel check on the return
   value from firmware.

 - Fix the commit allowing changing from global to non-global page table
   entries which inadvertently disallowed other safe attribute changes.

 - Fix sleeping in atomic during the arm_perf_teardown_cpu() code.

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: Relax ARM_SMCCC_ARCH_WORKAROUND_1 discovery
  arm_pmu: Use disable_irq_nosync when disabling SPI in CPU teardown hook
  arm64: mm: fix thinko in non-global page table attribute check

Pull Documentation build fix from Jonathan Corbet:
 "The Sphinx 1.7 release broke the build process for reasons that are
  mostly our fault.

  This is a single fix cherry-picked from docs-next that restores docs
  buildability for all supported Sphinx versions"

* tag 'docs-4.16-fix' of git://git.lwn.net/linux:
  Documentation/sphinx: Fix Directive import error