Maxime reported the following memory leak regression due to commit
dbc8358c ("mm/nommu: use alloc_pages_exact() rather than its own
implementation").

On v3.19, I am facing a memory leak.  Each time I run a command one page
is lost.  Here an example with busybox's free command:

  / # free
               total       used       free     shared    buffers     cached
  Mem:          7928       1972       5956          0          0        492
  -/+ buffers/cache:       1480       6448
  / # free
               total       used       free     shared    buffers     cached
  Mem:          7928       1976       5952          0          0        492
  -/+ buffers/cache:       1484       6444
  / # free
               total       used       free     shared    buffers     cached
  Mem:          7928       1980       5948          0          0        492
  -/+ buffers/cache:       1488       6440
  / # free
               total       used       free     shared    buffers     cached
  Mem:          7928       1984       5944          0          0        492
  -/+ buffers/cache:       1492       6436
  / # free
               total       used       free     shared    buffers     cached
  Mem:          7928       1988       5940          0          0        492
  -/+ buffers/cache:       1496       6432

At some point, the system fails to sastisfy 256KB allocations:

  free: page allocation failure: order:6, mode:0xd0
  CPU: 0 PID: 67 Comm: free Not tainted 3.19.0-05389-gacf2cf1-dirty #64
  Hardware name: STM32 (Device Tree Support)
    show_stack+0xb/0xc
    warn_alloc_failed+0x97/0xbc
    __alloc_pages_nodemask+0x295/0x35c
    __get_free_pages+0xb/0x24
    alloc_pages_exact+0x19/0x24
    do_mmap_pgoff+0x423/0x658
    vm_mmap_pgoff+0x3f/0x4e
    load_flat_file+0x20d/0x4f8
    load_flat_binary+0x3f/0x26c
    search_binary_handler+0x51/0xe4
    do_execveat_common+0x271/0x35c
    do_execve+0x19/0x1c
    ret_fast_syscall+0x1/0x4a
  Mem-info:
  Normal per-cpu:
  CPU    0: hi:    0, btch:   1 usd:   0
  active_anon:0 inactive_anon:0 isolated_anon:0
   active_file:0 inactive_file:0 isolated_file:0
   unevictable:123 dirty:0 writeback:0 unstable:0
   free:1515 slab_reclaimable:17 slab_unreclaimable:139
   mapped:0 shmem:0 pagetables:0 bounce:0
   free_cma:0
  Normal free:6060kB min:352kB low:440kB high:528kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:492kB isolated(anon):0ks
  lowmem_reserve[]: 0 0
  Normal: 23*4kB (U) 22*8kB (U) 24*16kB (U) 23*32kB (U) 23*64kB (U) 23*128kB (U) 1*256kB (U) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 6060kB
  123 total pagecache pages
  2048 pages of RAM
  1538 free pages
  66 reserved pages
  109 slab pages
  -46 pages shared
  0 pages swap cached
  nommu: Allocation of length 221184 from process 67 (free) failed
  Normal per-cpu:
  CPU    0: hi:    0, btch:   1 usd:   0
  active_anon:0 inactive_anon:0 isolated_anon:0
   active_file:0 inactive_file:0 isolated_file:0
   unevictable:123 dirty:0 writeback:0 unstable:0
   free:1515 slab_reclaimable:17 slab_unreclaimable:139
   mapped:0 shmem:0 pagetables:0 bounce:0
   free_cma:0
  Normal free:6060kB min:352kB low:440kB high:528kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:492kB isolated(anon):0ks
  lowmem_reserve[]: 0 0
  Normal: 23*4kB (U) 22*8kB (U) 24*16kB (U) 23*32kB (U) 23*64kB (U) 23*128kB (U) 1*256kB (U) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 6060kB
  123 total pagecache pages
  Unable to allocate RAM for process text/data, errno 12 SEGV

This problem happens because we allocate ordered page through
__get_free_pages() in do_mmap_private() in some cases and we try to free
individual pages rather than ordered page in free_page_series().  In
this case, freeing pages whose refcount is not 0 won't be freed to the
page allocator so memory leak happens.

To fix the problem, this patch changes __get_free_pages() to
alloc_pages_exact() since alloc_pages_exact() returns
physically-contiguous pages but each pages are refcounted.

Fixes: dbc8358c

 ("mm/nommu: use alloc_pages_exact() rather than its own implementation").
Reported-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Tested-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <stable@vger.kernel.org>	[3.19]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We (the Ocfs2 project) recently moved the location of our ocfs2-tools
git tree and project web page.  The pertinent discussion can be seen
here:

  https://oss.oracle.com/pipermail/ocfs2-devel/2015-February/010579.html



The following patch updates the Ocfs2 documentation in MAINTAINERS,
ocfs2.txt, and dlmfs.txt.  I added our new official web page, changed
the location of our tools git tree and removed the link to Joel's
ancient kernel git tree - Andrew has handled our patches for a while
now.

Signed-off-by: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Merge tag 'hwmon-for-linus-v4.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging

Pull hwmon fix from Guenter Roeck:
 "Add missing return value check to ads7828 driver"

* tag 'hwmon-for-linus-v4.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
  hwmon: (ads7828) Check return value of devm_regmap_init_i2c

Pull sound fixes from Takashi Iwai:
 "Most of changes in this pull request are about the fixes of crash of
  FireWire drivers at hot-unplugging.  In addition, there are a few
  HD-audio fixes (removal of wrong static, a pin quirk for an ASUS mobo,
  a regression fix for runtime PM on Panther Point) and a long-standing
  (but fairly minor) bug of PCM core"

* tag 'sound-4.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: hda - Disable runtime PM for Panther Point again
  ALSA: hda: controller code - do not export static functions
  ALSA: pcm: Don't leave PREPARED state after draining
  ALSA: fireworks/bebob/dice/oxfw: make it possible to shutdown safely
  ALSA: fireworks/bebob/dice/oxfw: allow stream destructor after releasing runtime
  ALSA: firewire-lib: remove reference counting
  ALSA: fireworks/bebob/dice/oxfw: add reference-counting for FireWire unit
  ALSA: hda - Add pin configs for ASUS mobo with IDT 92HD73XX codec
  ALSA: firewire-lib: fix an unexpected byte sequence for micro sign

Pull btrfs fix from Chris Mason:
 "I'm still testing more fixes, but I wanted to get out the fix for the
  btrfs raid5/6 memory corruption I mentioned in my merge window pull"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: fix allocation size calculations in alloc_btrfs_bio

This is essentially a partial revert of the commit [b1920c21

:
'ALSA: hda - Enable runtime PM on Panther Point'].  There was a bug
report showing the HD-audio bus hang during runtime PM on HP Spectre
XT.

Reported-by: Dang Sananikone <dang.sananikone@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Pull xen bugfixes from David Vrabel:
 "Xen regression and bug fixes for 4.0-rc1

   - Fix two regressions introduced in 4.0-rc1 affecting PV/PVH guests
     in certain configurations.

   - Prevent pvscsi frontends bypassing backend checks.

   - Allow privcmd hypercalls to be preempted even on kernel with
     voluntary preemption.  This fixes soft-lockups with long running
     toolstack hypercalls (e.g., when creating/destroying large
     domains)"

* tag 'stable/for-linus-4.0-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  x86/xen: Initialize cr4 shadow for 64-bit PV(H) guests
  xen-scsiback: mark pvscsi frontend request consumed only after last read
  x86/xen: allow privcmd hypercalls to be preempted
  x86/xen: Make sure X2APIC_ENABLE bit of MSR_IA32_APICBASE is not set

Pull lguest fixes from Rusty Russell:
 "Lguest weird config build fix, and update to the documentation"

* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
  lguest: update help text.
  lguest: now depends on PCI

Pull livepatching fixes from Jiri Kosina:
 "Two tiny fixes for livepatching infrastructure:

   - extending RCU critical section to cover all accessess to
     RCU-protected variable, by Petr Mladek

   - proper format string passing to kobject_init_and_add(), by Jiri
     Kosina"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching:
  livepatch: RCU protect struct klp_func all the time when used in klp_ftrace_handler()
  livepatch: fix format string in kobject_init_and_add()

Pull HID fixes from Jiri Kosina:

 - a few fixes to Sony driver (rmmod breakage, spinlock initialization),
   by Antonio Ospite, Frank Praznik and Jiri Kosina

 - fix for wMaxInputLength handling regression in i2c-hid, by Seth
   Forshee

 - IRQ safety spinlock fix in sensor hub driver, by Srinivas Pandruvada

 - IRQ level sensitivity fix to i2c-hid to be compliant with the spec,
   by Mika Westerberg

 - a couple device ID additions piggy-backing on top of that

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid:
  HID: microsoft: Add ID for NE7K wireless keyboard
  HID: i2c-hid: Limit reads to wMaxInputLength bytes for input events
  HID: sony: fix uninitialized per-controller spinlock
  HID: sony: initialize sony_dev_list_lock properly
  HID: sony: Fix a WARNING shown when rmmod-ing the driver
  HID: sensor-hub: correct dyn_callback_lock IRQ-safe change
  HID: hid-sensor-hub: Correct documentation
  HID: saitek: add USB ID for older R.A.T. 7
  HID: i2c-hid: The interrupt should be level sensitive
  HID: wacom: Add missing ABS_MISC event and feature declaration for 27QHD

It is a bad idea to export static functions. GCC for some platforms
shows errors like:

  error: __ksymtab_azx_get_response causes a section type conflict

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Cc: <stable@vger.kernel.org> # v3.15+
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Commit 1e02ce4c

 ("x86: Store a per-cpu shadow copy of CR4")
introduced CR4 shadows.

These shadows are initialized in early boot code. The commit missed
initialization for 64-bit PV(H) guests that this patch adds.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

A request in the ring buffer mustn't be read after it has been marked
as consumed. Otherwise it might already have been reused by the
frontend without violating the ring protocol.

To avoid inconsistencies in the backend only work on a private copy
of the request. This will ensure a malicious guest not being able to
bypass consistency checks of the backend by modifying an active
request.

Signed-off-by: Juergen Gross <jgross@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

Hypercalls submitted by user space tools via the privcmd driver can
take a long time (potentially many 10s of seconds) if the hypercall
has many sub-operations.

A fully preemptible kernel may deschedule such as task in any upcall
called from a hypercall continuation.

However, in a kernel with voluntary or no preemption, hypercall
continuations in Xen allow event handlers to be run but the task
issuing the hypercall will not be descheduled until the hypercall is
complete and the ioctl returns to user space.  These long running
tasks may also trigger the kernel's soft lockup detection.

Add xen_preemptible_hcall_begin() and xen_preemptible_hcall_end() to
bracket hypercalls that may be preempted.  Use these in the privcmd
driver.

When returning from an upcall, call xen_maybe_preempt_hcall() which
adds a schedule point if if the current task was within a preemptible
hypercall.

Since _cond_resched() can move the task to a different CPU, clear and
set xen_in_preemptible_hcall around the call.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

Commit d524165c

 ("x86/apic: Check x2apic early") tests X2APIC_ENABLE
bit of MSR_IA32_APICBASE when CONFIG_X86_X2APIC is off and panics
the kernel when this bit is set.

Xen's PV guests will pass this MSR read to the hypervisor which will
return its version of the MSR, where this bit might be set. Make sure
we clear it before returning MSR value to the caller.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

When a PCM draining is performed to an empty stream that has been
already in PREPARED state, the current code just ignores and leaves as
it is, although the drain is supposed to set all such streams to SETUP
state.  This patch covers that overlooked case.

Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Microsoft Natural Wireless Ergonomic Keyboard 7000 has special My
Favorites 1..5 keys which are handled through a vendor-defined usage
page (0xff05).

Apply MS_ERGONOMY quirks handling to USB PID 0x071d (Microsoft Microsoft
2.4GHz Transceiver V1.0) so that the My Favorites 1..5 keys are reported
as KEY_F14..18 events.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=52841


Signed-off-by: Jakub Sitnicki <jsitnicki@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

d1c7e29e (HID: i2c-hid: prevent buffer overflow in early IRQ)
changed hid_get_input() to read ihid->bufsize bytes, which can be
more than wMaxInputLength. This is the case with the Dell XPS 13
9343, and it is causing events to be missed. In some cases the
missed events are releases, which can cause the cursor to jump or
freeze, among other problems. Limit the number of bytes read to
min(wMaxInputLength, ihid->bufsize) to prevent such problems.

Fixes: d1c7e29e

 "HID: i2c-hid: prevent buffer overflow in early IRQ"
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Per-controller spinlock needs to be properly initialized during device probe.

[jkosina@suse.cz: massage changelog]
[jkosina@suse.cz: drop hunk that has already been applied by previous
 patch]
Signed-off-by: Frank Praznik <frank.praznik@oh.rr.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

sony_dev_list_lock spinlock (which was introduced in d2d782fc

 ("HID: sony:
Prevent duplicate controller connections") is not being initialized properly.
Fix that.

Reported-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

A part of these drivers, especially BeBoB driver, are programmed to wait
some events. Thus the drivers should not destroy any data in .remove()
context.

This commit moves some destructors from 'struct fw_driver.remove()' to
'struct snd_card.private_free()' to shutdown safely.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Cc: <stable@vger.kernel.org> # 3.19+
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Currently stream destructor in each driver has a problem to be called in
a context in which sound card object is released, because the destructors
call amdtp_stream_pcm_abort() and touch PCM runtime data.

The PCM runtime data is destroyed in application's context with
snd_pcm_close(), on the other hand PCM substream data is destroyed after
sound card object is released, in most case after all of ALSA character
devices are released. When PCM runtime is destroyed and PCM substream is
remained, amdtp_stream_pcm_abort() touches PCM runtime data and causes
Null-pointer-dereference.

This commit changes stream destructors and allows each driver to call
it after releasing runtime.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Cc: <stable@vger.kernel.org> # 3.19+
Signed-off-by: Takashi Iwai <tiwai@suse.de>

AMDTP helper functions increment/decrement reference counter for an
instance of FireWire unit, while it's complicated for each driver to
process error state.

In previous commit, each driver has the role of reference counting. This
commit removes this role from the helper function.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Cc: <stable@vger.kernel.org> # 3.19+
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Fireworks and Dice drivers try to touch instances of FireWire unit after
sound card object is released, while references to the unit is decremented
in .remove(). When unplugging during streaming, sound card object is
released after .remove(), thus Fireworks and Dice drivers causes GPF or
Null-pointer-dereferencing to application processes because an instance of
FireWire unit was already released.

This commit adds reference-counting for FireWire unit in drivers to allow
them to touch an instance of FireWire unit after .remove(). In most case,
any operations after .remove() may be failed safely.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Cc: <stable@vger.kernel.org> # 3.19+
Signed-off-by: Takashi Iwai <tiwai@suse.de>

BIOS doesn't seem to set up pins for 5.1 and the SPDIF out, so we need
to give explicitly here.

Reported-and-tested-by: Misan Thropos <misanthropos@gmx.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

The sign for microsecond (U+0085, MICRO SIGN) was encoded to '0x c2 b5'
by UTF-8 character encoding scheme. But the byte sequence was converted
to '0x c3 82 c2 b5' in a previous commit. As a result, the byte
sequence cannot represent microsecond sign in UTF-8 or ASCII. This
may confuse developers.

This commit replaces the sign to string expression with 'microseconds'
to purge superfluous troubles.

Fixes: 5c697e5b

("ALSA: firewire-lib: remove rx_blocks_for_midi quirk")
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

devm_regmap_init_i2c() can fail, thus add return value checking.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

.. 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
  ...

func->new_func has been accessed after rcu_read_unlock() in klp_ftrace_handler()
and therefore the access was not protected.

Signed-off-by: Petr Mladek <pmladek@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

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: Al Viro <viro@zeniv.linux.org.uk>

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

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

Signed-off-by: Al 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: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Al 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: David Howells <dhowells@redhat.com>
Signed-off-by: Al 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: David Howells <dhowells@redhat.com>
Signed-off-by: Al 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: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>