NFS4_OO_PURGE_CLOSE is not handled properly. To avoid memory leak, nfs4
stateid which is pointed by oo_last_closed_stid is freed in nfsd4_close(),
but NFS4_OO_PURGE_CLOSE isn't cleared meanwhile. So the stateid released in
THIS close procedure may be freed immediately in the coming encoding function.
Sorry that Signed-off-by was forgotten in last version.
Signed-off-by: Yanchuan Nian <ycnian@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

lk_rflags is never used anywhere, and rflags is not defined in struct
nfsd4_lock.
Signed-off-by: Yanchuan Nian <ycnian@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

Once we drop the lock here there's nothing keeping the client around:
the only lock still held is the xpt_lock on this socket, but this socket
no longer has any connection with the client so there's no way for other
code to know we're still using the client.

The solution is simple: all nfsd4_probe_callback does is set a few
variables and queue some work, so there's no reason we can't just keep
it under the lock.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

Dropping the session's reference count after the client's means we leave
a window where the session's se_client pointer is NULL.  An xpt_user
callback that encounters such a session may then crash:

[  303.956011] BUG: unable to handle kernel NULL pointer dereference at 0000000000000318
[  303.959061] IP: [<ffffffff81481a8e>] _raw_spin_lock+0x1e/0x40
[  303.959061] PGD 37811067 PUD 3d498067 PMD 0
[  303.959061] Oops: 0002 [#8] PREEMPT SMP
[  303.959061] Modules linked in: md5 nfsd auth_rpcgss nfs_acl snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_page_alloc microcode psmouse snd_timer serio_raw pcspkr evdev snd soundcore i2c_piix4 i2c_core intel_agp intel_gtt processor button nfs lockd sunrpc fscache ata_generic pata_acpi ata_piix uhci_hcd libata btrfs usbcore usb_common crc32c scsi_mod libcrc32c zlib_deflate floppy virtio_balloon virtio_net virtio_pci virtio_blk virtio_ring virtio
[  303.959061] CPU 0
[  303.959061] Pid: 264, comm: nfsd Tainted: G      D      3.8.0-ARCH+ #156 Bochs Bochs
[  303.959061] RIP: 0010:[<ffffffff81481a8e>]  [<ffffffff81481a8e>] _raw_spin_lock+0x1e/0x40
[  303.959061] RSP: 0018:ffff880037877dd8  EFLAGS: 00010202
[  303.959061] RAX: 0000000000000100 RBX: ffff880037a2b698 RCX: ffff88003d879278
[  303.959061] RDX: ffff88003d879278 RSI: dead000000100100 RDI: 0000000000000318
[  303.959061] RBP: ffff880037877dd8 R08: ffff88003c5a0f00 R09: 0000000000000002
[  303.959061] R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
[  303.959061] R13: 0000000000000318 R14: ffff880037a2b680 R15: ffff88003c1cbe00
[  303.959061] FS:  0000000000000000(0000) GS:ffff88003fc00000(0000) knlGS:0000000000000000
[  303.959061] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[  303.959061] CR2: 0000000000000318 CR3: 000000003d49c000 CR4: 00000000000006f0
[  303.959061] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  303.959061] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[  303.959061] Process nfsd (pid: 264, threadinfo ffff880037876000, task ffff88003c1fd0a0)
[  303.959061] Stack:
[  303.959061]  ffff880037877e08 ffffffffa03772ec ffff88003d879000 ffff88003d879278
[  303.959061]  ffff88003d879080 0000000000000000 ffff880037877e38 ffffffffa0222a1f
[  303.959061]  0000000000107ac0 ffff88003c22e000 ffff88003d879000 ffff88003c1cbe00
[  303.959061] Call Trace:
[  303.959061]  [<ffffffffa03772ec>] nfsd4_conn_lost+0x3c/0xa0 [nfsd]
[  303.959061]  [<ffffffffa0222a1f>] svc_delete_xprt+0x10f/0x180 [sunrpc]
[  303.959061]  [<ffffffffa0223d96>] svc_recv+0xe6/0x580 [sunrpc]
[  303.959061]  [<ffffffffa03587c5>] nfsd+0xb5/0x140 [nfsd]
[  303.959061]  [<ffffffffa0358710>] ? nfsd_destroy+0x90/0x90 [nfsd]
[  303.959061]  [<ffffffff8107ae00>] kthread+0xc0/0xd0
[  303.959061]  [<ffffffff81010000>] ? perf_trace_xen_mmu_set_pte_at+0x50/0x100
[  303.959061]  [<ffffffff8107ad40>] ? kthread_freezable_should_stop+0x70/0x70
[  303.959061]  [<ffffffff814898ec>] ret_from_fork+0x7c/0xb0
[  303.959061]  [<ffffffff8107ad40>] ? kthread_freezable_should_stop+0x70/0x70
[  303.959061] Code: ff ff 5d c3 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 65 48 8b 04 25 f0 c6 00 00 48 89 e5 83 80 44 e0 ff ff 01 b8 00 01 00 00 <3e> 66 0f c1 07 0f b6 d4 38 c2 74 0f 66 0f 1f 44 00 00 f3 90 0f
[  303.959061] RIP  [<ffffffff81481a8e>] _raw_spin_lock+0x1e/0x40
[  303.959061]  RSP <ffff880037877dd8>
[  303.959061] CR2: 0000000000000318
[  304.001218] ---[ end trace 2d809cd4a7931f5a ]---
[  304.001903] note: nfsd[264] exited with preempt_count 2
Reported-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

If a client sets an owner (or group_owner or acl) attribute on open for
create, and the mapping of that owner to an id fails, then we return
BAD_OWNER.  But BAD_OWNER is a seqid-mutating error, so we can't
shortcut the open processing that case: we have to at least look up the
owner so we can find the seqid to bump.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

This BUG_ON just crashes the thread a little earlier than it would
otherwise--it doesn't seem useful.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

We've now increased the size of the duplicate reply cache by quite a
bit, but the number of hash buckets has not changed. So, we've gone from
an average hash chain length of 16 in the old code to 4096 when the
cache is its largest. Change the code to scale out the number of buckets
with the max size of the cache.

At the same time, we also need to fix the hash function since the
existing one isn't really suitable when there are more than 256 buckets.
Move instead to use the stock hash_32 function for this. Testing on a
machine that had 2048 buckets showed that this gave a smaller
longest:average ratio than the existing hash function:

The formula here is longest hash bucket searched divided by average
number of entries per bucket at the time that we saw that longest
bucket:

    old hash: 68/(39258/2048) == 3.547404
    hash_32:  45/(33773/2048) == 2.728807
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

The typical case with the DRC is a cache miss, so if we keep track of
the max number of entries that we've ever walked over in a search, then
we should have a reasonable estimate of the longest hash chain that
we've ever seen.

With that, we'll also keep track of the total size of the cache when we
see the longest chain. In the case of a tie, we prefer to track the
smallest total cache size in order to properly gauge the worst-case
ratio of max vs. avg chain length.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

For presenting statistics relating to duplicate reply cache.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

Break out the function that compares the rqstp and checksum against a
reply cache entry. While we're at it, track the efficacy of the checksum
over the NFS data by tracking the cases where we would have incorrectly
matched a DRC entry if we had not tracked it or the length.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

The most common case is to do a search of the cache, followed by an
insert. In the case where we have to allocate an entry off the slab,
then we end up having to redo the search, which is wasteful.

Better optimize the code for the common case by eliminating the initial
search of the cache and always preallocating an entry. In the case of a
cache hit, we'll end up just freeing that entry but that's preferable to
an extra search.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

Since we only enforce an upper bound, not a lower bound, a "negative"
length can get through here.

The symptom seen was a warning when we attempt to a kmalloc with an
excessive size.
Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Cc: stable@kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

vfs_writev() updates the offset argument - but the code then passes the
offset to vfs_fsync_range(). Since offset now points to the offset after
what was just written, this is probably not what was intended

Introduced by face1502 "nfsd: use
vfs_fsync_range(), not O_SYNC, for stable writes".
Signed-off-by: Kent Overstreet <koverstreet@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: stable@vger.kernel.org
Reviewed-by: Zach Brown <zab@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

If we end up doing "goto out_nomem" in this function, we'll call
nfsd_reply_cache_shutdown. That will attempt to walk the LRU list and
free entries, but that list may not be initialized yet if the server is
starting up for the first time. It's also possible for the shrinker to
kick in before we've initialized the LRU list.

Rearrange the initialization so that the LRU list_head and cache size
are initialized before doing any of the allocations that might fail.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

It's not safe to call hlist_del() on a newly initialized hlist_node.
That leads to a NULL pointer dereference. Only do that if the entry
is hashed.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

Commit 1d9d8639 ("perf,x86: fix kernel crash with PEBS/BTS after
suspend/resume") introduces a link failure since
perf_restore_debug_store() is only defined for CONFIG_CPU_SUP_INTEL:

	arch/x86/power/built-in.o: In function `restore_processor_state':
	(.text+0x45c): undefined reference to `perf_restore_debug_store'

Fix it by defining the dummy function appropriately.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit 1d9d8639 ("perf,x86: fix kernel crash with PEBS/BTS after
suspend/resume") fixed a crash when doing PEBS performance profiling
after resuming, but in using init_debug_store_on_cpu() to restore the
DS_AREA mtrr it also resulted in a new WARN_ON() triggering.

init_debug_store_on_cpu() uses "wrmsr_on_cpu()", which in turn uses CPU
cross-calls to do the MSR update.  Which is not really valid at the
early resume stage, and the warning is quite reasonable.  Now, it all
happens to _work_, for the simple reason that smp_call_function_single()
ends up just doing the call directly on the CPU when the CPU number
matches, but we really should just do the wrmsr() directly instead.

This duplicates the wrmsr() logic, but hopefully we can just remove the
wrmsr_on_cpu() version eventually.
Reported-and-tested-by: Parag Warudkar <parag.lkml@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull btrfs fixes from Chris Mason:
 "Eric's rcu barrier patch fixes a long standing problem with our
  unmount code hanging on to devices in workqueue helpers.  Liu Bo
  nailed down a difficult assertion for in-memory extent mappings."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: fix warning of free_extent_map
  Btrfs: fix warning when creating snapshots
  Btrfs: return as soon as possible when edquot happens
  Btrfs: return EIO if we have extent tree corruption
  btrfs: use rcu_barrier() to wait for bdev puts at unmount
  Btrfs: remove btrfs_try_spin_lock
  Btrfs: get better concurrency for snapshot-aware defrag work

Users report that an extent map's list is still linked when it's actually
going to be freed from cache.

The story is that

a) when we're going to drop an extent map and may split this large one into
smaller ems, and if this large one is flagged as EXTENT_FLAG_LOGGING which means
that it's on the list to be logged, then the smaller ems split from it will also
be flagged as EXTENT_FLAG_LOGGING, and this is _not_ expected.

b) we'll keep ems from unlinking the list and freeing when they are flagged with
EXTENT_FLAG_LOGGING, because the log code holds one reference.

The end result is the warning, but the truth is that we set the flag
EXTENT_FLAG_LOGGING only during fsync.

So clear flag EXTENT_FLAG_LOGGING for extent maps split from a large one.
Reported-by: Johannes Hirte <johannes.hirte@fem.tu-ilmenau.de>
Reported-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

Pull kbuild fix from Michal Marek:
 "One fix for for make headers_install/headers_check to not require make
  3.81.  The requirement has been accidentally introduced in 3.7."

* 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild:
  kbuild: fix make headers_check with make 3.80

Pull OpenRISC bug fixes from Jonas Bonn:

 - The GPIO descriptor work has exposed how broken the non-GPIOLIB bits
   for OpenRISC were.  We now require GPIOLIB as this is the preferred
   way forward.

 - The system.h split introduced a bug in llist.h for arches using
   asm-generic/cmpxchg.h directly, which is currently only OpenRISC.
   The patch here moves two defines from asm-generic/atomic.h to
   asm-generic/cmpxchg.h to make things work as they should.

 - The VIRT_TO_BUS selector was added for OpenRISC, but OpenRISC does
   not have the virt_to_bus methods, so there's a patch to remove it
   again.

* tag 'for-3.9-rc3' of git://openrisc.net/jonas/linux:
  openrisc: remove HAVE_VIRT_TO_BUS
  asm-generic: move cmpxchg*_local defs to cmpxchg.h
  openrisc: require gpiolib

Pull char/misc fixes from Greg Kroah-Hartman:
 "Here are some tiny fixes for the w1 drivers and the final removal
  patch for getting rid of CONFIG_EXPERIMENTAL (all users of it are now
  gone from your tree, this just drops the Kconfig item itself.)

  All have been in the linux-next tree for a while"

* tag 'char-misc-3.9-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  final removal of CONFIG_EXPERIMENTAL
  w1: fix oops when w1_search is called from netlink connector
  w1-gpio: fix unused variable warning
  w1-gpio: remove erroneous __exit and __exit_p()
  ARM: w1-gpio: fix erroneous gpio requests

Pull sound fixes from Takashi Iwai:
 "A collection of small fixes, as expected for the middle rc:
   - A couple of fixes for potential NULL dereferences and out-of-range
     array accesses revealed by static code parsers
   - A fix for the wrong error handling detected by trinity
   - A regression fix for missing audio on some MacBooks
   - CA0132 DSP loader fixes
   - Fix for EAPD control of IDT codecs on machines w/o speaker
   - Fix a regression in the HD-audio widget list parser code
   - Workaround for the NuForce UDH-100 USB audio"

* tag 'sound-3.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: hda - Fix missing EAPD/GPIO setup for Cirrus codecs
  sound: sequencer: cap array index in seq_chn_common_event()
  ALSA: hda/ca0132 - Remove extra setting of dsp_state.
  ALSA: hda/ca0132 - Check download state of DSP.
  ALSA: hda/ca0132 - Check if dspload_image succeeded.
  ALSA: hda - Disable IDT eapd_switch if there are no internal speakers
  ALSA: hda - Fix snd_hda_get_num_raw_conns() to return a correct value
  ALSA: usb-audio: add a workaround for the NuForce UDH-100
  ALSA: asihpi - fix potential NULL pointer dereference
  ALSA: seq: Fix missing error handling in snd_seq_timer_open()

Pull DMA-mapping fix from Marek Szyprowski:
 "An important fix for all ARM architectures which use ZONE_DMA.
  Without it dma_alloc_* calls with GFP_ATOMIC flag might have allocated
  buffers outsize DMA zone."

* 'fixes-for-3.9' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping:
  ARM: DMA-mapping: add missing GFP_DMA flag for atomic buffer allocation

Pull MFD fixes from Samuel Ortiz:
 "This is the first batch of MFD fixes for 3.9.

  With this one we have:

   - An ab8500 build failure fix.
   - An ab8500 device tree parsing fix.
   - A fix for twl4030_madc remove routine to work properly (when
     built-in).
   - A fix for properly registering palmas interrupt handler.
   - A fix for omap-usb init routine to actually write into the
     hostconfig register.
   - A couple of warning fixes for ab8500-gpadc and tps65912"

* tag 'mfd-fixes-3.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/sameo/mfd-fixes:
  mfd: twl4030-madc: Remove __exit_p annotation
  mfd: ab8500: Kill "reg" property from binding
  mfd: ab8500-gpadc: Complain if we fail to enable vtvout LDO
  mfd: wm831x: Don't forward declare enum wm831x_auxadc
  mfd: twl4030-audio: Fix argument type for twl4030_audio_disable_resource()
  mfd: tps65912: Declare and use tps65912_irq_exit()
  mfd: palmas: Provide irq flags through DT/platform data
  mfd: Make AB8500_CORE select POWER_SUPPLY to fix build error
  mfd: omap-usb-host: Actually update hostconfig

Pull hwmon fixes from Guenter Roeck:
 "Bug fixes for pmbus, ltc2978, and lineage-pem drivers

  Added specific maintainer for some hwmon drivers"

* tag 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
  hwmon: (pmbus/ltc2978) Fix temperature reporting
  hwmon: (pmbus) Fix krealloc() misuse in pmbus_add_attribute()
  hwmon: (lineage-pem) Add missing terminating entry for pem_[input|fan]_attributes
  MAINTAINERS: Add maintainer for MAX6697, INA209, and INA2XX drivers

This patch fixes a kernel crash when using precise sampling (PEBS)
after a suspend/resume. Turns out the CPU notifier code is not invoked
on CPU0 (BP). Therefore, the DS_AREA (used by PEBS) is not restored properly
by the kernel and keeps it power-on/resume value of 0 causing any PEBS
measurement to crash when running on CPU0.

The workaround is to add a hook in the actual resume code to restore
the DS Area MSR value. It is invoked for all CPUS. So for all but CPU0,
the DS_AREA will be restored twice but this is harmless.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

During the transition to the generic parser, the hook to the codec
specific automute function was forgotten.  This resulted in the silent
output on some MacBooks.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

"chn" here is a number between 0 and 255, but ->chn_info[] only has
16 elements so there is a potential write beyond the end of the
array.

If the seq_mode isn't SEQ_2 then we let the individual drivers
(either opl3.c or midi_synth.c) handle it.  Those functions all
do a bounds check on "chn" so I haven't changed anything here.
The opl3.c driver has up to 18 channels and not 16.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

4740f73f "mfd: remove use of __devexit" removed the __devexit annotation
on the twl4030_madc_remove function, but left an __exit_p() present on the
pointer to this function. Using __exit_p was as wrong with the devexit in
place as it is now, but now we get a gcc warning about an unused function.

In order for the twl4030_madc_remove to work correctly in built-in code, we
have to remove the __exit_p.

Cc: Bill Pemberton <wfp5p@virginia.edu>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

spec->dsp_state is initialized to DSP_DOWNLOAD_INIT, no need to reset
and check it in ca0132_download_dsp().
Signed-off-by: Dylan Reid <dgreid@chromium.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Instead of using the dspload_is_loaded() function, check the dsp_state
that is kept in the spec.  The dspload_is_loaded() function returns
true if the DSP transfer was never started.  This false-positive leads
to multiple second delays when ca0132_setup_efaults() times out on
each write.
Signed-off-by: Dylan Reid <dgreid@chromium.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

If dspload_image() fails, it was ignored and dspload_wait_loaded() was
still called.  dsp_loaded should never be set to true in this case,
skip it.  The check in dspload_wait_loaded() return true if the DSP is
loaded or if it never started.
Signed-off-by: Dylan Reid <dgreid@chromium.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

The vm_flags introduced in 6d7825b1 ("mm/fremap.c: fix oops on error
path") is supposed to avoid a compiler warning about unitialized
vm_flags without changing the generated code.

However I am concerned that this is going to be very brittle, and fail
with some compiler versions. The failure could be either of:

- compiler could actually load vma->vm_flags before checking for the
  !vma condition, thus reintroducing the oops

- compiler could optimize out the !vma check, since the pointer just got
  dereferenced shortly before (so the compiler knows it can't be NULL!)

I propose reversing this part of the change and initializing vm_flags to 0
just to avoid the bogus uninitialized use warning.
Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Tommi Rantala <tt.rantala@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull fix for hlist_entry_safe() regression from Paul McKenney:
 "This contains a single commit that fixes a regression in
  hlist_entry_safe().  This macro references its argument twice, which
  can cause NULL-pointer errors.  This commit applies a gcc statement
  expression, creating a temporary variable to avoid the double
  reference.  This has been posted to LKML at

    https://lkml.org/lkml/2013/3/9/75.

  Kudos to CAI Qian, whose testing uncovered this, to Eric Dumazet, who
  spotted root cause, and to Li Zefan, who tested this commit."

* 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  list: Fix double fetch of pointer in hlist_entry_safe()

The current version of hlist_entry_safe() fetches the pointer twice,
once to test for NULL and the other to compute the offset back to the
enclosing structure.  This is OK for normal lock-based use because in
that case, the pointer cannot change.  However, when the pointer is
protected by RCU (as in "rcu_dereference(p)"), then the pointer can
change at any time.  This use case can result in the following sequence
of events:

1.	CPU 0 invokes hlist_entry_safe(), fetches the RCU-protected
	pointer as sees that it is non-NULL.

2.	CPU 1 invokes hlist_del_rcu(), deleting the entry that CPU 0
	just fetched a pointer to.  Because this is the last entry
	in the list, the pointer fetched by CPU 0 is now NULL.

3.	CPU 0 refetches the pointer, obtains NULL, and then gets a
	NULL-pointer crash.

This commit therefore applies gcc's "({ })" statement expression to
create a temporary variable so that the specified pointer is fetched
only once, avoiding the above sequence of events.  Please note that
it is the caller's responsibility to use rcu_dereference() as needed.
This allows RCU-protected uses to work correctly without imposing
any additional overhead on the non-RCU case.

Many thanks to Eric Dumazet for spotting root cause!
Reported-by: CAI Qian <caiqian@redhat.com>
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Li Zefan <lizefan@huawei.com>

Pull ext2, ext3, reiserfs, quota fixes from Jan Kara:
 "A fix for regression in ext2, and a format string issue in ext3.  The
  rest isn't too serious."

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  ext2: Fix BUG_ON in evict() on inode deletion
  reiserfs: Use kstrdup instead of kmalloc/strcpy
  ext3: Fix format string issues
  quota: add missing use of dq_data_lock in __dquot_initialize

Creating snapshot passes extent_root to commit its transaction,
but it can lead to the warning of checking root for quota in
the __btrfs_end_transaction() when someone else is committing
the current transaction.  Since we've recorded the needed root
in trans_handle, just use it to get rid of the warning.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>