Documentation: DT bindings: Tegra AHB: require the legacy base address for existing chips

Per Stephen Warren, note in the Tegra AHB DT binding documentation
that we specifically deprecate any attempt to use the IP block's
actual hardware base address, and advocate the use of the legacy
"off-by-four" address in the 'regs' property, for Tegra chips with
existing upstream Linux DT files that include a Tegra AHB node.  This
patch updates the documentation accordingly.

Changing the existing kernel DT data isn't under consideration because
Linux kernel DT data policy is to preserve compatibility between newer
DT data files and older kernels.  However, this additional step of
changing the documentation should discourage others from sending
kernel patches to try to change the legacy kernel DT data.
Furthermore, for out-of-tree software (such as bootloaders or other
operating systems) that may rely on Linux kernel DT binding
documentation as an ABI (but not the Linux kernel DT data itself),
such a change may allow future convergence with the Linux kernel DT
data without additional code changes.
Signed-off-by: NPaul Walmsley <paul@pwsan.com>
Cc: Paul Walmsley <pwalmsley@nvidia.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: Kumar Gala <galak@codeaurora.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Acked-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

amba: tegra-ahb: detect and correct bogus base address

From a hardware SoC integration point of view, the starting address of
this IP block in the existing Tegra SoC DT files is off by 4 bytes
from the actual base address.  Since we attempt to make old DT files
forward-compatible with newer kernels, we cannot fix the IP block base
address in old DT data. This patch works around the problem by
detecting the four byte base address offset in the driver code, and
correcting it if it's detected.  (In general, IP block base addresses
almost always have a null low byte.)

Future SoC DT data for Tegra AHB should use the correct Tegra AHB base
address, in cases where there is no DT data backward compatibility
requirement.

This patch is a revision of the patch originally titled
"amba: tegra-ahb: use correct base address for future chip support".
This revision implements changes requested by Russell King:

http://marc.info/?l=linux-tegra&m=142658851825062&w=2
http://marc.info/?l=linux-tegra&m=142658873925178&w=2Signed-off-by: NPaul Walmsley <paul@pwsan.com>
Cc: Paul Walmsley <pwalmsley@nvidia.com>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Hiroshi DOYU <hdoyu@nvidia.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: linux-kernel@vger.kernel.org
Acked-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

amba: tegra-ahb: fix register offsets in the macros

From a hardware SoC integration point of view, the offsets of the
Tegra AHB registers that are currently defined in tegra-ahb.c macros
are all off by four bytes.  Similarly, the starting address of this IP
block in our existing DT files is also off by four bytes.  Since we
attempt to make old DT files forward-compatible with newer kernels, we
cannot fix the IP block base address in old DT data.  However, we can
fix the offsets in the driver so that they are correct with respect to
the hardware, which is what this patch does.  And a subsequent patch
will allow the offset to be removed for DT 'compatible' strings used
in future DT files for newer Tegra chips that the kernel does not yet
support.
Signed-off-by: NPaul Walmsley <paul@pwsan.com>
Cc: Paul Walmsley <pwalmsley@nvidia.com>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Hiroshi DOYU <hdoyu@nvidia.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: linux-kernel@vger.kernel.org
Acked-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Several interrupt controllers support both edge and level interrupts, so
it's useful to provide that information in /proc/interrupts.
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

When trying to kexec into a new kernel on a platform where multiple CPU
cores are present, but no SMP bringup code is available yet, the
kexec_load system call fails with:

    kexec_load failed: Invalid argument

The SMP test added to machine_kexec_prepare() in commit 2103f6cb
("ARM: 7807/1: kexec: validate CPU hotplug support") wants to prohibit
kexec on SMP platforms where it cannot disable secondary CPUs.
However, this test is too strict: if the secondary CPUs couldn't be
enabled in the first place, there's no need to disable them later at
kexec time.  Hence skip the test in the absence of SMP bringup code.

This allows to add all CPU cores to the DTS from the beginning, without
having to implement SMP bringup first, improving DT compatibility.
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Acked-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Move shutdown and reboot related code to a separate file, out of
process.c.  This helps to avoid polluting process.c with non-process
related code.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Normally, when a CPU wants to clear a cache line to zero in the external
L2 cache, it would generate bus cycles to write each word as it would do
with any other data access.

However, a Cortex A9 connected to a L2C-310 has a specific feature where
the CPU can detect this operation, and signal that it wants to zero an
entire cache line.  This feature, known as Full Line of Zeros (FLZ),
involves a non-standard AXI signalling mechanism which only the L2C-310
can properly interpret.

There are separate enable bits in both the L2C-310 and the Cortex A9 -
the L2C-310 needs to be enabled and have the FLZ enable bit set in the
auxiliary control register before the Cortex A9 has this feature
enabled.

Unfortunately, the suspend code was not respecting this - it's not
obvious from the code:

swsusp_arch_suspend()
 cpu_suspend() /* saves the Cortex A9 auxiliary control register */
  arch_save_image()
  soft_restart() /* turns off FLZ in Cortex A9, and disables L2C */
   cpu_resume() /* restores the Cortex A9 registers, inc auxcr */

At this point, we end up with the L2C disabled, but the Cortex A9 with
FLZ enabled - which means any memset() or zeroing of a full cache line
will fail to take effect.

A similar issue exists in the resume path, but it's slightly more
complex:

swsusp_arch_suspend()
 cpu_suspend() /* saves the Cortex A9 auxiliary control register */
  arch_save_image() /* image with A9 auxcr saved */
...
swsusp_arch_resume()
 call_with_stack()
  arch_restore_image() /* restores image with A9 auxcr saved above */
  soft_restart() /* turns off FLZ in Cortex A9, and disables L2C */
   cpu_resume() /* restores the Cortex A9 registers, inc auxcr */

Again, here we end up with the L2C disabled, but Cortex A9 FLZ enabled.

There's no need to turn off the L2C in either of these two paths; there
are benefits from not doing so - for example, the page copies will be
faster with the L2C enabled.

Hence, fix this by providing a variant of soft_restart() which can be
used without turning the L2 cache controller off, and use it in both
of these paths to keep the L2C enabled across the respective resume
transitions.

Fixes: 8ef418c7 ("ARM: l2c: trial at enabling some Cortex-A9 optimisations")
Reported-by: NSean Cross <xobs@kosagi.com>
Tested-by: NSean Cross <xobs@kosagi.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This code calls cpu_resume() using a straight branch (b), so
now that we have moved cpu_resume() back to .text, this should
be moved there as well.
Acked-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This code calls cpu_resume() using a straight branch (b), so
now that we have moved cpu_resume() back to .text, this should
be moved there as well. Any direct references to symbols that will
remain in the .data section are replaced with explicit PC-relative
references.
Acked-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Move cpu_resume() to the .text section where it belongs. Change
the adr reference to sleep_save_sp to an explicit PC relative
reference so sleep_save_sp itself can remain in .data.

This helps prevent linker failure on large kernels, as the code
in the .data section may be too far away to be in range for normal
b/bl instructions.
Reviewed-by: NNicolas Pitre <nico@linaro.org>
Tested-by: NSudeep Holla <sudeep.holla@arm.com>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

When building a very large kernel, it is up to the linker to decide
when and where to insert stubs to allow calls to functions that are
out of range for the ordinary b/bl instructions.

However, since the kernel is built as a position dependent binary,
these stubs (aka veneers) may contain absolute addresses, which will
break far calls performed with the MMU off.

For instance, the call from __enable_mmu() in the .head.text section
to __turn_mmu_on() in the .idmap.text section may be turned into
something like this:

c0008168 <__enable_mmu>:
c0008168:       f020 0002       bic.w   r0, r0, #2
c000816c:       f420 5080       bic.w   r0, r0, #4096
c0008170:       f000 b846       b.w     c0008200 <____turn_mmu_on_veneer>
[...]
c0008200 <____turn_mmu_on_veneer>:
c0008200:       4778            bx      pc
c0008202:       46c0            nop
c0008204:       e59fc000        ldr     ip, [pc]
c0008208:       e12fff1c        bx      ip
c000820c:       c13dfae1        teqgt   sp, r1, ror #21
[...]
c13dfae0 <__turn_mmu_on>:
c13dfae0:       4600            mov     r0, r0
[...]

After adding --pic-veneer to the LDFLAGS, the veneer is emitted like
this instead:

c0008200 <____turn_mmu_on_veneer>:
c0008200:       4778            bx      pc
c0008202:       46c0            nop
c0008204:       e59fc004        ldr     ip, [pc, #4]
c0008208:       e08fc00c        add     ip, pc, ip
c000820c:       e12fff1c        bx      ip
c0008210:       013d7d31        teqeq   sp, r1, lsr sp
c0008214:       00000000        andeq   r0, r0, r0

Note that this particular example is best addressed by moving
.head.text and .idmap.text closer together, but this issue could
potentially affect any code that needs to execute with the
MMU off.
Acked-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This moves all fixup snippets to the .text.fixup section, which is
a special section that gets emitted along with the .text section
for each input object file, i.e., the snippets are kept much closer
to the code they refer to, which helps prevent linker failure on
large kernels.
Acked-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This introduces a new .text.fixup input section that gets emitted
together with the .text section for each input object file.

Note that

  *(.text)
  *(.text.fixup)

is not the same as

  *(.text .text.fixup)

and we are looking for the latter, to ensure that fixup snippets that
are assembled into a separate section in the object file do not end
up out of range for the relative branch instructions it contains if
the .text section itself grows very large.

This helps prevent linker failures on large ARM kernels.
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arm64 builds with GCC 5 have caused the __asmeq assertions in the PSCI
calling code to fire, so move the ARM PSCI calls out of line into their
own assembly file for consistency and to safeguard against the same
issue occuring with the 32-bit toolchain.

[will: brought into line with arm64 implementation]
Reported-by: NAndy Whitcroft <apw@canonical.com>
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

When the patch for e16343c4 (ARM: 8160/1: drop warning about
return_address not using unwind tables) was created there was still more
code in said branch. Probably this simplification was just missed during
conflict resolution when the patch was applied.
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This patch makes it possible to enter zImage in Thumb mode for ARMv7-M
(Cortex-M) CPUs that do not support ARM mode. The kernel entry is also
made in Thumb mode.

[ukl: fix spelling in commit log, return early in call_cache_fn]
Signed-off-by: NJoachim Eastwood <manabian@gmail.com>
Tested-by: NStefan Agner <stefan@agner.ch>
Tested-by: NEzequiel Garcia <ezequiel@vanguardiasur.com.ar>
Tested-by: NChanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

When running the 32-bit ARM kernel on ARMv8 capable bare metal (e.g.,
32-bit Android userland and kernel on a Cortex-A53), or as a KVM guest
on a 64-bit host, we should advertise the availability of the Crypto
instructions, so that userland libraries such as OpenSSL may use them.
(Support for the v8 Crypto instructions in the 32-bit build was added
to OpenSSL more than six months ago)

This adds the ID feature bit detection, and sets elf_hwcap2 accordingly.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

The various CPU feature registers consist of 4-bit blocks that
represent signed quantities, whose positive values represent
incremental features, and whose negative values are reserved.

To improve forward compatibility, update the feature detection
code to take possible future higher values into account, but
ignore negative values.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This moves the .idmap.text section closer to .head.text, so that
relative branches are less likely to go out of range if the kernel
text gets bigger.
Acked-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This patch replaces the 'branch to setup()' instructions embedded
in the PROCINFO structs with the offset to that setup function
relative to the base of the struct. This preserves the position
independent nature of that field, but uses a data item rather
than an instruction.

This is mainly done to prevent linker failures on large kernels,
where the setup function is out of reach for the branch.
Acked-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Occasionally, there's a question about the method we use to find the
start of physical memory.  Add some documentation so we don't have to
keep repeating outselves on the mailing list.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

When using the IOMMU-backed DMA ops for a device, we store a pointer to
the dma_iommu_mapping structure (used to keep track of the address
space) in the archdata.mapping field of the struct device.

Rather than access this field directly, use the to_dma_iommu_mapping
helper in dma-mapping, so that we don't really care where the mapping
information is held.

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Make sure that we can read the "cache-level" property from the L2 cache
controller node, and ensure its value is 2.
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

SMP_ON_UP has been around for a while, and seems to be well-proven now.
Drop the EXPERIMENTAL tag from the option.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Even without an iommu, NO_KERNEL_MAPPING is still convenient to save on
kernel address space in places where we don't need a kernel mapping.
Implement support for it in the two places where we're creating an
expensive mapping.

__alloc_from_pool uses an internal pool from which we already have
virtual addresses, so it's not relevant, and __alloc_simple_buffer uses
alloc_pages, which will always return a lowmem page, which is already
mapped into kernel space, so we can't prevent a mapping for it in that
case.
Signed-off-by: NJasper St. Pierre <jstpierre@mecheye.net>
Signed-off-by: NCarlo Caione <carlo@caione.org>
Reviewed-by: NRob Clark <robdclark@gmail.com>
Reviewed-by: NDaniel Drake <dsd@endlessm.com>
Acked-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

The pci_mmap_page_range() API should be written to expect offset
values representing PCI memory resource addresses as seen by user
space, through the pci_resource_to_user() API.

ARM relies on the standard implementation of pci_resource_to_user()
which actually is an identity map and exports to user space
PCI memory resources as they are stored in PCI devices resources
structures, which represent CPU physical addresses (fixed-up using
BUS to CPU address conversions) not PCI bus addresses.

Therefore, on ARM platforms where the mapping between CPU and BUS
address is not a 1:1 the current pci_mmap_page_range() implementation is
erroneous, in that an additional shift is applied to an already fixed-up
offset passed from userspace.

Hence, this patch removes the mem_offset from the pgoff calculation
since the offset as passed from user space already represents the CPU
physical address corresponding to the resource to be mapped, ie no
additional offset should be applied.

Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: NBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Currently, interworking calls on module boundaries are not supported,
and are handled by the same error handling code path as non-interworking
calls whose targets are simply out of range.

Before modifying the handling of those out-of-range jump and call
relocations in a subsequent patch, move the handling of interworking
restrictions out of it.
Acked-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

.. after extensive statistical analysis of my G+ polling, I've come to
the inescapable conclusion that internet polls are bad.

Big surprise.

But "Hurr durr I'ma sheep" trounced "I like online polls" by a 62-to-38%
margin, in a poll that people weren't even supposed to participate in.
Who can argue with solid numbers like that? 5,796 votes from people who
can't even follow the most basic directions?

In contrast, "v4.0" beat out "v3.20" by a slimmer margin of 56-to-44%,
but with a total of 29,110 votes right now.

Now, arguably, that vote spread is only about 3,200 votes, which is less
than the almost six thousand votes that the "please ignore" poll got, so
it could be considered noise.

But hey, I asked, so I'll honor the votes.

Pull ext4 fixes from Ted Ts'o:
 "Ext4 bug fixes.

  We also reserved code points for encryption and read-only images (for
  which the implementation is mostly just the reserved code point for a
  read-only feature :-)"

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: fix indirect punch hole corruption
  ext4: ignore journal checksum on remount; don't fail
  ext4: remove duplicate remount check for JOURNAL_CHECKSUM change
  ext4: fix mmap data corruption in nodelalloc mode when blocksize < pagesize
  ext4: support read-only images
  ext4: change to use setup_timer() instead of init_timer()
  ext4: reserve codepoints used by the ext4 encryption feature
  jbd2: complain about descriptor block checksum errors

Pull more vfs updates from Al Viro:
 "Assorted stuff from this cycle.  The big ones here are multilayer
  overlayfs from Miklos and beginning of sorting ->d_inode accesses out
  from David"

* 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (51 commits)
  autofs4 copy_dev_ioctl(): keep the value of ->size we'd used for allocation
  procfs: fix race between symlink removals and traversals
  debugfs: leave freeing a symlink body until inode eviction
  Documentation/filesystems/Locking: ->get_sb() is long gone
  trylock_super(): replacement for grab_super_passive()
  fanotify: Fix up scripted S_ISDIR/S_ISREG/S_ISLNK conversions
  Cachefiles: Fix up scripted S_ISDIR/S_ISREG/S_ISLNK conversions
  VFS: (Scripted) Convert S_ISLNK/DIR/REG(dentry->d_inode) to d_is_*(dentry)
  SELinux: Use d_is_positive() rather than testing dentry->d_inode
  Smack: Use d_is_positive() rather than testing dentry->d_inode
  TOMOYO: Use d_is_dir() rather than d_inode and S_ISDIR()
  Apparmor: Use d_is_positive/negative() rather than testing dentry->d_inode
  Apparmor: mediated_filesystem() should use dentry->d_sb not inode->i_sb
  VFS: Split DCACHE_FILE_TYPE into regular and special types
  VFS: Add a fallthrough flag for marking virtual dentries
  VFS: Add a whiteout dentry type
  VFS: Introduce inode-getting helpers for layered/unioned fs environments
  Infiniband: Fix potential NULL d_inode dereference
  posix_acl: fix reference leaks in posix_acl_create
  autofs4: Wrong format for printing dentry
  ...

Pull ARM fix from Russell King:
 "Just one fix this time around.  __iommu_alloc_buffer() can cause a
  BUG() if dma_alloc_coherent() is called with either __GFP_DMA32 or
  __GFP_HIGHMEM set.  The patch from Alexandre addresses this"

* 'fixes' of git://ftp.arm.linux.org.uk/~rmk/linux-arm:
  ARM: 8305/1: DMA: Fix kzalloc flags in __iommu_alloc_buffer()

X-Coverup: just ask spender
Cc: stable@vger.kernel.org
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

use_pde()/unuse_pde() in ->follow_link()/->put_link() resp.

Cc: stable@vger.kernel.org
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

As it is, we have debugfs_remove() racing with symlink traversals.
Supply ->evict_inode() and do freeing there - inode will remain
pinned until we are done with the symlink body.

And rip the idiocy with checking if dentry is positive right after
we'd verified debugfs_positive(), which is a stronger check...

Cc: stable@vger.kernel.org
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

I've noticed significant locking contention in memory reclaimer around
sb_lock inside grab_super_passive(). Grab_super_passive() is called from
two places: in icache/dcache shrinkers (function super_cache_scan) and
from writeback (function __writeback_inodes_wb). Both are required for
progress in memory allocator.

Grab_super_passive() acquires sb_lock to increment sb->s_count and check
sb->s_instances. It seems sb->s_umount locked for read is enough here:
super-block deactivation always runs under sb->s_umount locked for write.
Protecting super-block itself isn't a problem: in super_cache_scan() sb
is protected by shrinker_rwsem: it cannot be freed if its slab shrinkers
are still active. Inside writeback super-block comes from inode from bdi
writeback list under wb->list_lock.

This patch removes locking sb_lock and checks s_instances under s_umount:
generic_shutdown_super() unlinks it under sb->s_umount locked for write.
New variant is called trylock_super() and since it only locks semaphore,
callers must call up_read(&sb->s_umount) instead of drop_super(sb) when
they're done.
Signed-off-by: NKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Fanotify probably doesn't want to watch autodirs so make it use d_can_lookup()
rather than d_is_dir() when checking a dir watch and give an error on fake
directories.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Fix up the following scripted S_ISDIR/S_ISREG/S_ISLNK conversions (or lack
thereof) in cachefiles:

 (1) Cachefiles mostly wants to use d_can_lookup() rather than d_is_dir() as
     it doesn't want to deal with automounts in its cache.

 (2) Coccinelle didn't find S_IS* expressions in ASSERT() statements in
     cachefiles.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Convert the following where appropriate:

 (1) S_ISLNK(dentry->d_inode) to d_is_symlink(dentry).

 (2) S_ISREG(dentry->d_inode) to d_is_reg(dentry).

 (3) S_ISDIR(dentry->d_inode) to d_is_dir(dentry).  This is actually more
     complicated than it appears as some calls should be converted to
     d_can_lookup() instead.  The difference is whether the directory in
     question is a real dir with a ->lookup op or whether it's a fake dir with
     a ->d_automount op.

In some circumstances, we can subsume checks for dentry->d_inode not being
NULL into this, provided we the code isn't in a filesystem that expects
d_inode to be NULL if the dirent really *is* negative (ie. if we're going to
use d_inode() rather than d_backing_inode() to get the inode pointer).

Note that the dentry type field may be set to something other than
DCACHE_MISS_TYPE when d_inode is NULL in the case of unionmount, where the VFS
manages the fall-through from a negative dentry to a lower layer.  In such a
case, the dentry type of the negative union dentry is set to the same as the
type of the lower dentry.

However, if you know d_inode is not NULL at the call site, then you can use
the d_is_xxx() functions even in a filesystem.

There is one further complication: a 0,0 chardev dentry may be labelled
DCACHE_WHITEOUT_TYPE rather than DCACHE_SPECIAL_TYPE.  Strictly, this was
intended for special directory entry types that don't have attached inodes.

The following perl+coccinelle script was used:

use strict;

my @callers;
open($fd, 'git grep -l \'S_IS[A-Z].*->d_inode\' |') ||
    die "Can't grep for S_ISDIR and co. callers";
@callers = <$fd>;
close($fd);
unless (@callers) {
    print "No matches\n";
    exit(0);
}

my @cocci = (
    '@@',
    'expression E;',
    '@@',
    '',
    '- S_ISLNK(E->d_inode->i_mode)',
    '+ d_is_symlink(E)',
    '',
    '@@',
    'expression E;',
    '@@',
    '',
    '- S_ISDIR(E->d_inode->i_mode)',
    '+ d_is_dir(E)',
    '',
    '@@',
    'expression E;',
    '@@',
    '',
    '- S_ISREG(E->d_inode->i_mode)',
    '+ d_is_reg(E)' );

my $coccifile = "tmp.sp.cocci";
open($fd, ">$coccifile") || die $coccifile;
print($fd "$_\n") || die $coccifile foreach (@cocci);
close($fd);

foreach my $file (@callers) {
    chomp $file;
    print "Processing ", $file, "\n";
    system("spatch", "--sp-file", $coccifile, $file, "--in-place", "--no-show-diff") == 0 ||
	die "spatch failed";
}

[AV: overlayfs parts skipped]
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Use d_is_positive() rather than testing dentry->d_inode in SELinux to get rid
of direct references to d_inode outside of the VFS.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>