We need to create the $O/scripts/perl/Perf-Trace-Util/ directory too.

Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

That is not used in perf where we have the LOST events.

Without this patch we get:

[root@doppio ~]# perf lock report | head -3
  Warning: Error: expected 'data' but read 'overwrite'

So, to make the same perf command work with kernels with and without
this field, introduce variants for the parsing routines to not warn the
user in such case.

Discussed-with: Steven Rostedt <rostedt@goodmis.org>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Correct typos in perf bench & perf sched help text.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20100331113100.cc898487.randy.dunlap@oracle.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>

Fix spello in user message.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Cc: Paul Mackerra <paulus@samba.org>s
LKML-Reference: <20100331113056.2c7df509.randy.dunlap@oracle.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>

Using 'pahole --packable' I found some structs that could be reorganized
to eliminate alignment holes, in some cases getting them to be cacheline
multiples.

[acme@doppio linux-2.6-tip]$ codiff perf.old ~/bin/perf
builtin-annotate.c:
  struct perf_session    |   -8
  struct perf_header     |   -8
 2 structs changed

builtin-diff.c:
  struct sample_data         |   -8
 1 struct changed
  diff__process_sample_event |   -8
 1 function changed, 8 bytes removed, diff: -8

builtin-sched.c:
  struct sched_atom      |   -8
 1 struct changed

builtin-timechart.c:
  struct per_pid         |   -8
 1 struct changed
  cmd_timechart          |  -16
 1 function changed, 16 bytes removed, diff: -16

builtin-probe.c:
  struct perf_probe_point |   -8
  struct perf_probe_event |   -8
 2 structs changed
  opt_add_probe_event     |   -3
 1 function changed, 3 bytes removed, diff: -3

util/probe-finder.c:
  struct probe_finder      |   -8
 1 struct changed
  find_kprobe_trace_events |  -16
 1 function changed, 16 bytes removed, diff: -16

/home/acme/bin/perf:
 4 functions changed, 43 bytes removed, diff: -43
[acme@doppio linux-2.6-tip]$

Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Esc + Enter should be enough warning to avoid accidentaly exiting from
the browser.

Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Suggested-by: Ingo Molnar <molnar@elte.hu>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Semantic conflict: arch/x86/kernel/cpu/perf_event_intel_ds.c

Merge reason: pick up latest fixes, fix the conflict
Signed-off-by: Ingo Molnar <mingo@elte.hu>

* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus:
  hvc_console: Fix race between hvc_close and hvc_remove
  virtio: disable multiport console support.
  virtio: console makes incorrect assumption about virtio API
  virtio: console: Fix early_put_chars usage
  MAINTAINERS: Put the virtio-console entry in correct alphabetical order

I don't claim to understand the tty layer, but it seems like hvc_open and
hvc_close should be balanced in their kref reference counting.

Right now we get a kref every call to hvc_open:

        if (hp->count++ > 0) {
                tty_kref_get(tty); <----- here
                spin_unlock_irqrestore(&hp->lock, flags);
                hvc_kick();
                return 0;
        } /* else count == 0 */

        tty->driver_data = hp;

        hp->tty = tty_kref_get(tty); <------ or here if hp->count was 0

But hvc_close has:

        tty_kref_get(tty);

        if (--hp->count == 0) {
...
                /* Put the ref obtained in hvc_open() */
                tty_kref_put(tty);
...
        }

        tty_kref_put(tty);

Since the outside kref get/put balance we only do a single kref_put when
count reaches 0.

The patch below changes things to call tty_kref_put once for every
hvc_close call, and with that my machine boots fine.
Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Move MULTIPORT feature and related config changes
out of exported headers, and disable the feature
at runtime.

At this point, it seems less risky to keep code around
until we can enable it than rip it out completely.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

The get_buf() API sets the second arg to the number of bytes *written*
by the other side; in this case it should be zero as these are output buffers.

lguest gets this right (obviously kvm's console doesn't), resulting in
continual buildup of console writes.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Amit Shah <amit.shah@redhat.com>

Currently early_put_chars is not used by virtio_console because it can
only be used once a port has been found, at which point it's too late
because it is no longer needed. This patch should fix it.
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Move around the entry for virtio-console to keep the file sorted.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

rwsems can be used with IRQs disabled, particularily in early boot
before IRQs are enabled.  Currently the spin_unlock_irq() usage in the
slow-patch will unconditionally enable interrupts and cause problems
since interrupts are not yet initialized or enabled.

This patch uses save/restore versions of IRQ spinlocks in the slowpath
to ensure interrupts are not unintentionally disabled.
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

	If nfs atomic open implementation ends up doing open request from
->d_revalidate() codepath and gets an error from server, return that error
to caller explicitly and don't bother with lookup_instantiate_filp() at all.
->d_revalidate() can return an error itself just fine...

See
	http://bugzilla.kernel.org/show_bug.cgi?id=15674
	http://marc.info/?l=linux-kernel&m=126988782722711&w=2

for original report.
Reported-by: Daniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  perf, x86: Enable Nehalem-EX support
  perf kmem: Fix breakage introduced by 5a0e3ad6 slab.h script

Merge branch 'davinci-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/khilman/linux-davinci

* 'davinci-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/khilman/linux-davinci:
  davinci: fix compile warning: <mach/da8xx.h>: #include <linux/platform_device.h>
  davinci: DM365: fix duplicate default IRQ priorities
  davinci: edma: clear events in edma_start()
  davinci: da8xx/omap-l1: fix build error when CONFIG_DAVINCI_MUX is undefined
  davinci: timers: don't enable timer until clocksource is initialized

Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-tip

* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-tip:
  x86: Fix double enable_IR_x2apic() call on SMP kernel on !SMP boards
  x86: Increase CONFIG_NODES_SHIFT max to 10
  ibft, x86: Change reserve_ibft_region() to find_ibft_region()
  x86, hpet: Fix bug in RTC emulation
  x86, hpet: Erratum workaround for read after write of HPET comparator
  bootmem, x86: Fix 32bit numa system without RAM on node 0
  nobootmem, x86: Fix 32bit numa system without RAM on node 0
  x86: Handle overlapping mptables
  x86: Make e820_remove_range to handle all covered case
  x86-32, resume: do a global tlb flush in S4 resume

This hushes the following warning:

arch/arm/mach-davinci/include/mach/da8xx.h:104: warning: ‘struct platform_device’
declared inside parameter list
arch/arm/mach-davinci/include/mach/da8xx.h:104: warning: its scope is only this
definition or declaration, which is probably not what you want
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

* 'for-linus' of git://git.monstr.eu/linux-2.6-microblaze:
  microblaze: Remove unused variable from ptrace
  microblaze: io.h: Add io big-endian function
  microblaze: Enable memory leak detector
  microblaze: Fix futex code
  microblaze: Fix ftrace_update_ftrace_func panic

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
  ALSA: mixart: range checking proc file
  ALSA: hda - Fix a wrong array range check in patch_realtek.c
  ALSA: ASoC: move dma_data from snd_soc_dai to snd_soc_pcm_stream
  ALSA: hda - Enable amplifiers on Acer Inspire 6530G
  ASoC: Only do WM8994 bias off transition from standby
  ASoC: Don't use DCS_DATAPATH_BUSY for WM hubs devices
  ASoC: Don't do runtime wm_hubs DC servo updates if using offset correction
  ASoC: Support second DC servo readback method for wm_hubs
  ASoC: Avoid wraparound in wm_hubs DC servo correction
  ALSA: echoaudio - Eliminate use after free
  ALSA: i2c: cleanup: change parameter to pointer
  ALSA: hda - Add MSI blacklist for Aopen MZ915-M
  ASoC: OMAP: Fix capture pointer handling for OMAP1510 to work correctly with recent ALSA PCM code
  ALSA: hda - Update document about MSI and interrupts
  ALSA: hda: Fix 0 dB offset for Lenovo Thinkpad models using AD1981
  ALSA: hda - Add missing printk argument in previous patch
  ASoC: Fix passing platform_data to ac97 bus users and fix a leak
  ALSA: hda - Fix ADC/MUX assignment of ALC269 codec
  ALSA: hda - Fix invalid bit values passed to snd_hda_codec_amp_stereo()
  ASoC: wm8994: playback => capture

* 'slabh' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc:
  nodemask: include slab.h from drivers/base/node.c

Order the debugfs statistics correctly.  The values displayed through a
seq_printf() statement should be in the same order as the names in the
format string.

In the 'Lookups' line, objects created ('crt=') and lookups timed out
('tmo=') have their values transposed.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

In NOMMU mode, the FRV segment handling is broken because KERNEL_DS ==
USER_DS.  This causes tests of the following sort:

	/* don't pin down non-user-based iovecs */
	if (segment_eq(get_fs(), KERNEL_DS))
		return NULL;

to malfunction.

To fix this, make USER_DS the top of RAM instead of the top of the non-IO
address space, and make KERNEL_DS one more than the top of the non-IO
address space.

Also get rid of FRV's __addr_ok() as nothing uses it.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Hide uncached_access() when pgprot_noncached is not #defined.  This prevents
the following warning:

	  CC      drivers/char/mem.o
	drivers/char/mem.c:229: warning: 'uncached_access' defined but not used

Repairs d7d4d849 ("drivers/char/mem.c:
cleanups").
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

On exit paths in mxc_rtc_probe() method some resources are not freed
correctly.

This patch fixes:
* unrequested memory region containing imx RTC registers
* iounmap() isn't called on exit_free_pdata branch
* clock get rate is called for freed clock source
* clock isn't disabled on exit_put_clk branch

To simplify the fix managed device resources are used.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Vladimir Zapolskiy <vzapolskiy@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Presently, memcg's FILE_MAPPED accounting has following race with
move_account (happens at rmdir()).

    increment page->mapcount (rmap.c)
    mem_cgroup_update_file_mapped()           move_account()
					      lock_page_cgroup()
					      check page_mapped() if
					      page_mapped(page)>1 {
						FILE_MAPPED -1 from old memcg
						FILE_MAPPED +1 to old memcg
					      }
					      .....
					      overwrite pc->mem_cgroup
					      unlock_page_cgroup()
    lock_page_cgroup()
    FILE_MAPPED + 1 to pc->mem_cgroup
    unlock_page_cgroup()

Then,
	old memcg (-1 file mapped)
	new memcg (+2 file mapped)

This happens because move_account see page_mapped() which is not guarded
by lock_page_cgroup().  This patch adds FILE_MAPPED flag to page_cgroup
and move account information based on it.  Now, all checks are synchronous
with lock_page_cgroup().
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Balbir Singh <balbir@in.ibm.com>
Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Andrea Righi <arighi@develer.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When we look into pagemap using page-types with option -p, the value of
pfn for hugepages looks wrong (see below.) This is because pte was
evaluated only once for one vma although it should be updated for each
hugepage.  This patch fixes it.

  $ page-types -p 3277 -Nl -b huge
  voffset   offset  len     flags
  7f21e8a00 11e400  1       ___U___________H_G________________
  7f21e8a01 11e401  1ff     ________________TG________________
               ^^^
  7f21e8c00 11e400  1       ___U___________H_G________________
  7f21e8c01 11e401  1ff     ________________TG________________
               ^^^

One hugepage contains 1 head page and 511 tail pages in x86_64 and each
two lines represent each hugepage.  Voffset and offset mean virtual
address and physical address in the page unit, respectively.  The
different hugepages should not have the same offset value.

With this patch applied:

  $ page-types -p 3386 -Nl -b huge
  voffset   offset   len    flags
  7fec7a600 112c00   1      ___UD__________H_G________________
  7fec7a601 112c01   1ff    ________________TG________________
               ^^^
  7fec7a800 113200   1      ___UD__________H_G________________
  7fec7a801 113201   1ff    ________________TG________________
               ^^^
               OK

More info:

- This patch modifies walk_page_range()'s hugepage walker.  But the
  change only affects pagemap_read(), which is the only caller of hugepage
  callback.

- Without this patch, hugetlb_entry() callback is called per vma, that
  doesn't match the natural expectation from its name.

- With this patch, hugetlb_entry() is called per hugepte entry and the
  callback can become much simpler.
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The log of commit edaac8e3 ("ratelimit:
Fix/allow use in atomic contexts"), indicates that we want to suppress the
callback when the trylock fails.
Signed-off-by: Yong Zhang <yong.zhang@windriver.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When __ratelimit() returns 1 this means that we can go ahead.
Signed-off-by: Yong Zhang <yong.zhang@windriver.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

To prevent from wrongly using the return value.

[akpm@linux-foundation.org: fix spello]
Signed-off-by: Yong Zhang <yong.zhang@windriver.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

commit dcefafb6 ("/dev/mem: dont allow seek to last page") inadvertently
disabled rewinding on /dev/mem.

This broke x86info for example.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Requested by hch, for consistency now it is exported.

Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Anton Blanchard <anton@samba.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@suse.cz>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit 148f948b (vfs: Introduce new
helpers for syncing after writing to O_SYNC file or IS_SYNC inode) broke
the raw driver.

We now call through generic_file_aio_write -> generic_write_sync ->
vfs_fsync_range.  vfs_fsync_range has:

        if (!fop || !fop->fsync) {
                ret = -EINVAL;
                goto out;
        }

But drivers/char/raw.c doesn't set an fsync method.

We have two options: fix it or remove the raw driver completely.  I'm
happy to do either, the fact this has been broken for so long suggests it
is rarely used.

The patch below adds an fsync method to the raw driver.  My knowledge of
the block layer is pretty sketchy so this could do with a once over.

If we instead decide to remove the raw driver, this patch might still be
useful as a backport to 2.6.33 and 2.6.32.
Signed-off-by: Anton Blanchard <anton@samba.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <jens.axboe@oracle.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Tested-by: Jeff Moyer <jmoyer@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Since Valentin's email address @siemens.com is no longer valid, it's time
to change it to the one that actually works so that I don't have to
manually forward patches against mb862xx to him every time.
Signed-off-by: Alexander Shishkin <virtuoso@slind.org>
Acked-by: Valentin Sitdikov <v.sitdikov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mb862xxfb_accel built as a separate module, but it does not have a
MODULE_LICENSE, so it taints the kernel.  Add a MODULE_LICENSE to it (same
as mb862xxfb license).

mb862xxfb_accel: module license 'unspecified' taints kernel.

Or should mb862xxfb_accel be built into the mb862xxfb binary file instead?
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Alexander Shishkin <virtuoso@slind.org>
Cc: Valentin Sitdikov <v.sitdikov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Shaohua Li reported his tmpfs streaming I/O test can lead to make oom.
The test uses a 6G tmpfs in a system with 3G memory.  In the tmpfs, there
are 6 copies of kernel source and the test does kbuild for each copy.  His
investigation shows the test has a lot of rotated anon pages and quite few
file pages, so get_scan_ratio calculates percent[0] (i.e.  scanning
percent for anon) to be zero.  Actually the percent[0] shoule be a big
value, but our calculation round it to zero.

Although before commit 84b18490 ("vmscan: get_scan_ratio() cleanup") , we
have the same problem too.  But the old logic can rescue percent[0]==0
case only when priority==0.  It had hided the real issue.  I didn't think
merely streaming io can makes percent[0]==0 && priority==0 situation.  but
I was wrong.

So, definitely we have to fix such tmpfs streaming io issue.  but anyway I
revert the regression commit at first.

This reverts commit 84b18490.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reported-by: Shaohua Li <shaohua.li@intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

I hit this when we had a bug in IDR for a few days.  Basically sysfs would
fail to create new inodes since it uses an IDR and therefore class_create
would fail.

While we are unlikely to see this fail we may as well handle it instead of
oopsing.
Signed-off-by: Anton Blanchard <anton@samba.org>
Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

btrfs relocate_file_extent_cluster() calls us with NULL filp:

  [ 4005.426805] BUG: unable to handle kernel NULL pointer dereference at 00000021
  [ 4005.426818] IP: [<c109a130>] page_cache_sync_readahead+0x18/0x3e
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Yan Zheng <yanzheng@21cn.com>
Reported-by: Kirill A. Shutemov <kirill@shutemov.name>
Tested-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>