It is now identical to bar_init().
Signed-off-by: NJan Beulich <jbeulich@suse.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

Signed-off-by: NJan Beulich <jbeulich@suse.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

The kernel.h macro DIV_ROUND_UP performs the computation
(((n) + (d) - 1) /(d)) but is perhaps more readable.

The Coccinelle script used to make this change is as follows:
@haskernel@
@@

#include <linux/kernel.h>

@depends on haskernel@
expression n,d;
@@

(
- (n + d - 1) / d
+ DIV_ROUND_UP(n,d)
|
- (n + (d - 1)) / d
+ DIV_ROUND_UP(n,d)
)
Signed-off-by: NAmitoj Kaur Chawla <amitoj1606@gmail.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

System workqueues have been able to handle high level of concurrency
for a long time now and there's no reason to use dedicated workqueues
just to gain concurrency.  Replace dedicated xenbus_frontend_wq with the
use of system_wq.

Unlike a dedicated per-cpu workqueue created with create_workqueue(),
system_wq allows multiple work items to overlap executions even on
the same CPU; however, a per-cpu workqueue doesn't have any CPU
locality or global ordering guarantees unless the target CPU is
explicitly specified and the increase of local concurrency shouldn't
make any difference.

In this case, there is only a single work item, increase of concurrency
level by switching to system_wq should not make any difference.
Signed-off-by: NBhaktipriya Shridhar <bhaktipriya96@gmail.com>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

System workqueues have been able to handle high level of concurrency
for a long time now and there's no reason to use dedicated workqueues
just to gain concurrency.  Replace dedicated xen_pcibk_wq with the
use of system_wq.

Unlike a dedicated per-cpu workqueue created with create_workqueue(),
system_wq allows multiple work items to overlap executions even on
the same CPU; however, a per-cpu workqueue doesn't have any CPU
locality or global ordering guarantees unless the target CPU is
explicitly specified and thus the increase of local concurrency shouldn't
make any difference.

Since the work items could be pending, flush_work() has been used in
xen_pcibk_disconnect(). xen_pcibk_xenbus_remove() calls free_pdev()
which in turn calls xen_pcibk_disconnect() for every pdev to ensure that
there is no pending task while disconnecting the driver.
Signed-off-by: NBhaktipriya Shridhar <bhaktipriya96@gmail.com>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

This will match how PMU errors are reported at check_hw_exists()'s
msr_fail label, which is reached when VPMU initialzation fails.
Signed-off-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: NJuergen Gross <jgross@suse.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

The pv_time_ops structure contains a function pointer for the
"steal_clock" functionality used only by KVM and Xen on ARM. Xen on x86
uses its own mechanism to account for the "stolen" time a thread wasn't
able to run due to hypervisor scheduling.

Add support in Xen arch independent time handling for this feature by
moving it out of the arm arch into drivers/xen and remove the x86 Xen
hack.
Signed-off-by: NJuergen Gross <jgross@suse.com>
Reviewed-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: NStefano Stabellini <sstabellini@kernel.org>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

Replace explicit computation of vma page count by a call to
vma_pages().
Signed-off-by: NMuhammad Falak R Wani <falakreyaz@gmail.com>
Reviewed-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>

The EFI DT parameters for bare metal are located under /chosen node,
while for Xen Dom0 they are located under /hyperviosr/uefi node. These
parameters under /chosen and /hyperviosr/uefi are not expected to appear
at the same time.

Parse these EFI parameters and initialize EFI like the way for bare
metal except the runtime services because the runtime services for Xen
Dom0 are available through hypercalls and they are always enabled. So it
sets the EFI_RUNTIME_SERVICES flag if it finds /hyperviosr/uefi node and
bails out in arm_enable_runtime_services() when EFI_RUNTIME_SERVICES
flag is set already.
Signed-off-by: NShannon Zhao <shannon.zhao@linaro.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Signed-off-by: NMatt Fleming <matt@codeblueprint.co.uk>

Sometimes it needs to check if there is a subnode of given node in FDT
by given name. Introduce this helper to get the subnode if it exists.

CC: Rob Herring <robh@kernel.org>
Signed-off-by: NShannon Zhao <shannon.zhao@linaro.org>
Acked-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: NRob Herring <robh@kernel.org>
Tested-by: NJulien Grall <julien.grall@arm.com>

When running on Xen hypervisor, runtime services are supported through
hypercall. Add a Xen specific function to initialize runtime services.
Signed-off-by: NShannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Tested-by: NJulien Grall <julien.grall@arm.com>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>

Move x86 specific codes to architecture directory and export those EFI
runtime service functions. This will be useful for initializing runtime
service on ARM later.
Signed-off-by: NShannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Tested-by: NJulien Grall <julien.grall@arm.com>
Signed-off-by: NStefano Stabellini <sstabellini@kernel.org>

Add a "uefi" node under /hypervisor node in FDT, then Linux kernel could
scan this to get the UEFI information.

CC: Rob Herring <robh@kernel.org>
Signed-off-by: NShannon Zhao <shannon.zhao@linaro.org>
Acked-by: NRob Herring <robh@kernel.org>
Reviewed-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Tested-by: NJulien Grall <julien.grall@arm.com>

Move xen_early_init() before efi_init(), then when calling efi_init()
could initialize Xen specific UEFI.

Check if it runs on Xen hypervisor through the flat dts.

Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: NShannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: NJulien Grall <julien.grall@arm.com>
Tested-by: NJulien Grall <julien.grall@arm.com>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>

The kernel will get the event-channel IRQ through
HVM_PARAM_CALLBACK_IRQ.
Signed-off-by: NShannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: NJulien Grall <julien.grall@arm.com>
Tested-by: NJulien Grall <julien.grall@arm.com>

This new delivery type which is for ARM shares the same value with
HVM_PARAM_CALLBACK_TYPE_VECTOR which is for x86.

val[15:8] is flag: val[7:0] is a PPI.
To the flag, bit 8 stands the interrupt mode is edge(1) or level(0) and
bit 9 stands the interrupt polarity is active low(1) or high(0).
Signed-off-by: NShannon Zhao <shannon.zhao@linaro.org>
Acked-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: NJulien Grall <julien.grall@arm.com>
Tested-by: NJulien Grall <julien.grall@arm.com>

Sync the changes of HVM_PARAM_CALLBACK_VIA ABI introduced by
Xen commit <ca5c54b6ff05> (public/hvm: export the HVM_PARAM_CALLBACK_VIA
ABI in the API).
Signed-off-by: NShannon Zhao <shannon.zhao@linaro.org>
Acked-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Tested-by: NJulien Grall <julien.grall@arm.com>

Add a bus_notifier for AMBA bus device in order to map the device
mmio regions when DOM0 booting with ACPI.
Signed-off-by: NShannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: NJulien Grall <julien.grall@arm.com>
Tested-by: NJulien Grall <julien.grall@arm.com>

Add a bus_notifier for platform bus device in order to map the device
mmio regions when DOM0 booting with ACPI.
Signed-off-by: NShannon Zhao <shannon.zhao@linaro.org>
Acked-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Tested-by: NJulien Grall <julien.grall@arm.com>

Add a new type of Xen map space for Dom0 to map device's MMIO region.
Signed-off-by: NShannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: NJulien Grall <julien.grall@arm.com>
Tested-by: NJulien Grall <julien.grall@arm.com>

Use xen_xlate_map_ballooned_pages to setup grant table. Then it doesn't
rely on DT or ACPI to pass the start address and size of grant table.
Signed-off-by: NShannon Zhao <shannon.zhao@linaro.org>
Acked-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: NJulien Grall <julien.grall@arm.com>
Tested-by: NJulien Grall <julien.grall@arm.com>

Make xen_xlate_map_ballooned_pages work with 64K pages. In that case
Kernel pages are 64K in size but Xen pages remain 4K in size. Xen pfns
refer to 4K pages.
Signed-off-by: NShannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: NJulien Grall <julien.grall@arm.com>
Tested-by: NJulien Grall <julien.grall@arm.com>

Move xlated_setup_gnttab_pages to common place, so it can be reused by
ARM to setup grant table.

Rename it to xen_xlate_map_ballooned_pages.
Signed-off-by: NShannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: NJulien Grall <julien.grall@arm.com>
Tested-by: NJulien Grall <julien.grall@arm.com>

ACPI 6.0 introduces a new table STAO to list the devices which are used
by Xen and can't be used by Dom0. On Xen virtual platforms, the physical
UART is used by Xen. So here it hides UART from Dom0.

CC: "Rafael J. Wysocki" <rjw@rjwysocki.net> (supporter:ACPI)
CC: Len Brown <lenb@kernel.org> (supporter:ACPI)
CC: linux-acpi@vger.kernel.org (open list:ACPI)
Signed-off-by: NShannon Zhao <shannon.zhao@linaro.org>
Acked-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Pull fuse fix from Miklos Szeredi:
 "This makes sure userspace filesystems are not broken by the parallel
  lookups and readdir feature"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
  fuse: serialize dirops by default

Pull overlayfs fixes from Miklos Szeredi:
 "This contains fixes for a dentry leak, a regression in 4.6 noticed by
  Docker users and missing write access checking in truncate"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: warn instead of error if d_type is not supported
  ovl: get_write_access() in truncate
  ovl: fix dentry leak for default_permissions

overlay needs underlying fs to support d_type. Recently I put in a
patch in to detect this condition and started failing mount if
underlying fs did not support d_type.

But this breaks existing configurations over kernel upgrade. Those who
are running docker (partially broken configuration) with xfs not
supporting d_type, are surprised that after kernel upgrade docker does
not run anymore.

https://github.com/docker/docker/issues/22937#issuecomment-229881315

So instead of erroring out, detect broken configuration and warn
about it. This should allow existing docker setups to continue
working after kernel upgrade.
Signed-off-by: NVivek Goyal <vgoyal@redhat.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Fixes: 45aebeaf ("ovl: Ensure upper filesystem supports d_type")
Cc: <stable@vger.kernel.org> 4.6

Pull MIPS fix from Ralf Baechle:
 "Only a single fix for 4.7 pending at this point.  It fixes an issue
  that may lead to corruption of the cache mode bits in the page table"

* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus:
  MIPS: Fix possible corruption of cache mode by mprotect.

Pull powerpc fixes from Michael Ellerman:

 - tm: Always reclaim in start_thread() for exec() class syscalls from
   Cyril Bur

 - tm: Avoid SLB faults in treclaim/trecheckpoint when RI=0 from Michael
   Neuling

 - eeh: Fix wrong argument passed to eeh_rmv_device() from Gavin Shan

 - Initialise pci_io_base as early as possible from Darren Stevens

* tag 'powerpc-4.7-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc: Initialise pci_io_base as early as possible
  powerpc/tm: Avoid SLB faults in treclaim/trecheckpoint when RI=0
  powerpc/eeh: Fix wrong argument passed to eeh_rmv_device()
  powerpc/tm: Always reclaim in start_thread() for exec() class syscalls

Pull drm fixes frlm Dave Airlie:
 "Just some AMD and Intel fixes, the AMD ones are further production
  Polaris fixes, and the Intel ones fix some early timeouts, some PCI ID
  changes and a couple of other fixes.

  Still a bit Internet challenged here, hopefully end of next week will
  solve it"

* tag 'drm-fixes-for-v4.7-rc6' of git://people.freedesktop.org/~airlied/linux:
  drm/i915: Fix missing unlock on error in i915_ppgtt_info()
  drm/amd/powerplay: workaround for UVD clock issue
  drm/amdgpu: add ACLK_CNTL setting for polaris10
  drm/amd/powerplay: fix issue uvd dpm can't enabled on Polaris11.
  drm/amd/powerplay: Workaround for Memory EDC Error on Polaris10.
  drm/i915: Removing PCI IDs that are no longer listed as Kabylake.
  drm/i915: Add more Kabylake PCI IDs.
  drm/i915: Avoid early timeout during AUX transfers
  drm/i915/hsw: Avoid early timeout during LCPLL disable/restore
  drm/i915/lpt: Avoid early timeout during FDI PHY reset
  drm/i915/bxt: Avoid early timeout during PLL enable
  drm/i915: Refresh cached DP port register value on resume
  drm/amd/powerplay: Update CKS on/ CKS off voltage offset calculation
  drm/amd/powerplay: disable FFC.
  drm/amd/powerplay: add some definition for FFC feature on polaris.

Pull spi fixes from Mark Brown:
 "A few small driver-specific fixes for SPI, all in the normal important
  if you hit them category especially the rockchip driver fix which
  addresses a race which has been exposed more frequently with some
  recent performance improvements"

* tag 'spi-fix-v4.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
  spi: sunxi: fix transfer timeout
  spi: sun4i: fix FIFO limit
  spi: rockchip: Signal unfinished DMA transfers
  spi: spi-ti-qspi: Suspend the queue before removing the device

Merge tag 'regulator-fix-v4.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator

Pull regulator fixes from Mark Brown:
 "Two small fixes for the regulator subsystem - one fixing a crash with
  one of the devices supported by the max77620 driver, another fixing
  startup for the anatop regulator when it starts up with the regulator
  in bypass mode"

* tag 'regulator-fix-v4.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator:
  regulator: max77620: check for valid regulator info
  regulator: anatop: allow regulator to be in bypass mode

Pull clk fixes from Stephen Boyd:
 "A small fix for the newly added oxnas clk driver and a handful of
  rockchip clk driver fixes for newly added rk3399 support"

* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
  clk: Fix return value check in oxnas_stdclk_probe()
  clk: rockchip: release io resource when failing to init clk on rk3399
  clk: rockchip: fix cpuclk registration error handling
  clk: rockchip: Revert "clk: rockchip: reset init state before mmc card initialization"
  clk: rockchip: fix incorrect parent for rk3399's {c,g}pll_aclk_perihp_src
  clk: rockchip: mark rk3399 GIC clocks as critical
  clk: rockchip: initialize flags of clk_init_data in mmc-phase clock

here's a batch of i915 fixes for 4.7.

* tag 'drm-intel-fixes-2016-06-30' of git://anongit.freedesktop.org/drm-intel:
  drm/i915: Fix missing unlock on error in i915_ppgtt_info()
  drm/i915: Removing PCI IDs that are no longer listed as Kabylake.
  drm/i915: Add more Kabylake PCI IDs.
  drm/i915: Avoid early timeout during AUX transfers
  drm/i915/hsw: Avoid early timeout during LCPLL disable/restore
  drm/i915/lpt: Avoid early timeout during FDI PHY reset
  drm/i915/bxt: Avoid early timeout during PLL enable
  drm/i915: Refresh cached DP port register value on resume

Just a few more late fixes for Polaris cards.

* 'drm-fixes-4.7' of git://people.freedesktop.org/~agd5f/linux:
  drm/amd/powerplay: workaround for UVD clock issue
  drm/amdgpu: add ACLK_CNTL setting for polaris10
  drm/amd/powerplay: fix issue uvd dpm can't enabled on Polaris11.
  drm/amd/powerplay: Workaround for Memory EDC Error on Polaris10.
  drm/amd/powerplay: Update CKS on/ CKS off voltage offset calculation
  drm/amd/powerplay: disable FFC.
  drm/amd/powerplay: add some definition for FFC feature on polaris.

The following testcase may result in a page table entries with a invalid
CCA field being generated:

static void *bindstack;

static int sysrqfd;

static void protect_low(int protect)
{
	mprotect(bindstack, BINDSTACK_SIZE, protect);
}

static void sigbus_handler(int signal, siginfo_t * info, void *context)
{
	void *addr = info->si_addr;

	write(sysrqfd, "x", 1);

	printf("sigbus, fault address %p (should not happen, but might)\n",
	       addr);
	abort();
}

static void run_bind_test(void)
{
	unsigned int *p = bindstack;

	p[0] = 0xf001f001;

	write(sysrqfd, "x", 1);

	/* Set trap on access to p[0] */
	protect_low(PROT_NONE);

	write(sysrqfd, "x", 1);

	/* Clear trap on access to p[0] */
	protect_low(PROT_READ | PROT_WRITE | PROT_EXEC);

	write(sysrqfd, "x", 1);

	/* Check the contents of p[0] */
	if (p[0] != 0xf001f001) {
		write(sysrqfd, "x", 1);

		/* Reached, but shouldn't be */
		printf("badness, shouldn't happen but does\n");
		abort();
	}
}

int main(void)
{
	struct sigaction sa;

	sysrqfd = open("/proc/sysrq-trigger", O_WRONLY);

	if (sigprocmask(SIG_BLOCK, NULL, &sa.sa_mask)) {
		perror("sigprocmask");
		return 0;
	}

	sa.sa_sigaction = sigbus_handler;
	sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART;
	if (sigaction(SIGBUS, &sa, NULL)) {
		perror("sigaction");
		return 0;
	}

	bindstack = mmap(NULL,
			 BINDSTACK_SIZE,
			 PROT_READ | PROT_WRITE | PROT_EXEC,
			 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
	if (bindstack == MAP_FAILED) {
		perror("mmap bindstack");
		return 0;
	}

	printf("bindstack: %p\n", bindstack);

	run_bind_test();

	printf("done\n");

	return 0;
}

There are multiple ingredients for this:

 1) PAGE_NONE is defined to _CACHE_CACHABLE_NONCOHERENT, which is CCA 3
    on all platforms except SB1 where it's CCA 5.
 2) _page_cachable_default must have bits set which are not set
    _CACHE_CACHABLE_NONCOHERENT.
 3) Either the defective version of pte_modify for XPA or the standard
    version must be in used.  However pte_modify for the 36 bit address
    space support is no affected.

In that case additional bits in the final CCA mode may generate an invalid
value for the CCA field.  On the R10000 system where this was tracked
down for example a CCA 7 has been observed, which is Uncached Accelerated.

Fixed by:

 1) Using the proper CCA mode for PAGE_NONE just like for all the other
    PAGE_* pte/pmd bits.
 2) Fix the two affected variants of pte_modify.

Further code inspection also shows the same issue to exist in pmd_modify
which would affect huge page systems.

Issue in pte_modify tracked down by Alastair Bridgewater, PAGE_NONE
and pmd_modify issue found by me.

The history of this goes back beyond Linus' git history.  Chris Dearman's
commit 35133692 ("[MIPS] Allow setting of
the cache attribute at run time.") missed the opportunity to fix this
but it was originally introduced in lmo commit
d523832cf12007b3242e50bb77d0c9e63e0b6518 ("Missing from last commit.")
and 32cc38229ac7538f2346918a09e75413e8861f87 ("New configuration option
CONFIG_MIPS_UNCACHED.")
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
Reported-by: NAlastair Bridgewater <alastair.bridgewater@gmail.com>

Pull ACPI fix from Rafael Wysocki:
 "Fix an expression in the ACPI PCI IRQ management code added by a
  recent commit that overlooked missing parens in it, so the result of
  the computation is incorrect in some cases (Sinan Kaya)"

* tag 'acpi-4.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI,PCI,IRQ: correct operator precedence

Pull power management fixes from Rafael Wysocki:
 "Three cpufreq fixes, one in the core (stable-candidate) and two in
  drivers (intel_pstate and cpufreq-dt).

  Specifics:

   - Fix a recent intel_pstate regression that caused the number of
     wakeups to increase significantly on an idle system in some cases
     due to excessive synchronize_sched() invocations (Rafael Wysocki).

   - Fix unnecessary invocations of WARN_ON() in the cpufreq core after
     cpufreq has been suspended introduced during the 4.6 cycla (Rafael
     Wysocki).

   - Fix an error code path in the cpufreq-dt-platdev driver that
     forgets to drop a reference to a DT node (Masahiro Yamada)"

* tag 'pm-4.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  cpufreq: Avoid false-positive WARN_ON()s in cpufreq_update_policy()
  cpufreq: dt: call of_node_put() before error out
  intel_pstate: Do not clear utilization update hooks on policy changes

Pull vfs fixes from Al Viro:
 "Tmpfs readdir throughput regression fix (this cycle) + some -stable
  fodder all over the place.

  One missing bit is Miklos' tonight locks.c fix - NFS folks had already
  grabbed that one by the time I woke up ;-)"

[ The locks.c fix came through the nfsd tree just moments ago ]

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  namespace: update event counter when umounting a deleted dentry
  9p: use file_dentry()
  ceph: fix d_obtain_alias() misuses
  lockless next_positive()
  libfs.c: new helper - next_positive()
  dcache_{readdir,dir_lseek}(): don't bother with nested ->d_lock