We did before, in the end -- but it was at the bottom of a long stack of
functions. Add an inline wrapper get_valid_domain_for_dev() which will
use the cached one _first_ and only make the out-of-line call if it's
not already set.

This takes the average time taken for a 1-page intel_map_sg() from 5961
cycles to 4812 cycles on my Lenovo x200s test box -- a modest 20%.
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

* git://git.infradead.org/iommu-2.6:
  intel-iommu: Don't use identity mapping for PCI devices behind bridges
  intel-iommu: Use iommu_should_identity_map() at startup time too.
  intel-iommu: No mapping for non-PCI devices
  intel-iommu: Restore DMAR_BROKEN_GFX_WA option for broken graphics drivers
  intel-iommu: Add iommu_should_identity_map() function
  intel-iommu: Fix reattaching of devices to identity mapping domain
  intel-iommu: Don't set identity mapping for bypassed graphics devices
  intel-iommu: Fix dma vs. mm page confusion with aligned_nrpages()

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6:
  ieee1394: sbp2: add support for disks >2 TB (and 16 bytes long CDBs)
  firewire: sbp2: add support for disks >2 TB (and 16 bytes long CDBs)
  firewire: core: do not DMA-map stack addresses

This way they'll be properly initialized early enough for users that may
touch them before the framebuffer has been registered.

Drivers that allocate their fb_info structure some other way (like
matrocfb's broken static allocation) need to be fixed up appropriately.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

do_execve() and ptrace_attach() return -EINTR if
mutex_lock_interruptible(->cred_guard_mutex) fails.

This is not right, change the code to return ERESTARTNOINTR.

Perhaps we should also change proc_pid_attr_write().
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Acked-by: NRoland McGrath <roland@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In include/linux/sysrq.h the constant EINVAL is being used but is undefined
if include/linux/errno.h is not included before.

Fix this by adding #include <linux/errno.h> at the beginning.
Signed-off-by: NTobias Doerffel <tobias.doerffel@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Correct the CLKVAL_F field value of VIDEO MAIN CONTROLLER 0 REGITSTER.

Frame Rate is 1 / [ { (VSPW+1) + (VBPD+1) + (LIINEVAL + 1) + (VFPD+1)
} x {(HSPW+1) + (HBPD +1)
+ (HFPD+1) + (HOZVAL + 1) } x { ( CLKVAL+1 ) / ( Frequency of Clock
source ) } ] and VCLK = Video Clock Source / (CLKVAL +1).

therefore CLKVAL_F should be "CLKVAL_F = Frequency of Clock source / pixel
clock * refresh".

for this, I added refresh value in platform data like below.

static struct s3c_fb_pd_win xxx_fb_win0 = {
	/* this is to ensure we use win0 */
	.win_mode = {
		.refresh	= 60,
		.pixclock	= (66+4+2+480)*(15+5+3+800),
		.left_margin	= 66,
		.right_margin	= 2,
		.upper_margin	= 15,
		.lower_margin	= 3,
		.hsync_len	= 4,
		.vsync_len	= 5,
		.xres		= 480,
		.yres		= 800,
	},
	.max_bpp	= 32,
	.default_bpp	= 24,
};

static struct s3c_fb_platdata xxx_lcd_pdata __initdata = {
	.win[0]		= &xxx_fb_win0,
	.vidcon0	= VIDCON0_VIDOUT_RGB | VIDCON0_PNRMODE_RGB,
	.vidcon1	= VIDCON1_INV_HSYNC | VIDCON1_INV_VSYNC
			| VIDCON1_INV_VCLK | VIDCON1_INV_VDEN,
	.setup_gpio	= s5pc1xx_fb_gpio_setup_24bpp,
};

xxx_machine_init()
{
                   .
                   .
                   .
               s3c_fb_set_platdata(&xxx_lcd_pdata);
}

platform data defined in machine code should be setting using
s3c_fb_set_platdata().
Signed-off-by: NInKi Dae <inki.dae@samsung.com>
Cc: Kyungmin Park <kmpark@infradead.org>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

These warnings were observed on MIPS32 using 2.6.31-rc1 and gcc-4.2.0:

mm/page_alloc.c: In function 'alloc_pages_exact':
mm/page_alloc.c:1986: warning: passing argument 1 of 'virt_to_phys' makes pointer from integer without a cast

drivers/usb/mon/mon_bin.c: In function 'mon_alloc_buff':
drivers/usb/mon/mon_bin.c:1264: warning: passing argument 1 of 'virt_to_phys' makes pointer from integer without a cast

[akpm@linux-foundation.org: fix kernel/perf_counter.c too]
Signed-off-by: NKevin Cernekee <cernekee@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In testing a backport of the write_begin/write_end AOPs, a 10% re-read
regression was noticed when running iozone.  This regression was
introduced because the old AOPs would always do a mark_page_accessed(page)
after the commit_write, but when the new AOPs where introduced, the only
place this was kept was in pagecache_write_end().

This patch does the same thing in the generic case as what is done in
pagecache_write_end(), which is just to mark the page accessed before we
do write_end().
Signed-off-by: NJosef Bacik <jbacik@redhat.com>
Acked-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix the multithread program core thread message error.

This issue affects arches with neither has CORE_DUMP_USE_REGSET nor
ELF_CORE_COPY_TASK_REGS, ARM is one of them.

The thread message of core file is generated in elf_dump_thread_status.
The register values is set by elf_core_copy_task_regs in this function.

If an arch doesn't define ELF_CORE_COPY_TASK_REGS,
elf_core_copy_task_regs() will do nothing.  Then the core file will not
have the register message of thread.

So add elf_core_copy_regs to set regiser values if ELF_CORE_COPY_TASK_REGS
doesn't define.

The following is how to reproduce this issue:

cat 1.c
#include <stdio.h>
#include <pthread.h>
#include <assert.h>

void td1(void * i)
{
       while (1)
       {
               printf ("1\n");
               sleep (1);
       }

       return;
}

void td2(void * i)
{
       while (1)
       {
               printf ("2\n");
               sleep (1);
       }

       return;
}

int
main(int argc,char *argv[],char *envp[])
{
       pthread_t       t1,t2;

       pthread_create(&t1, NULL, (void*)td1, NULL);
       pthread_create(&t2, NULL, (void*)td2, NULL);

       sleep (10);

       assert(0);

       return (0);
}
arm-xxx-gcc -g -lpthread 1.c -o 1
copy 1.c and 1 to a arm board.
Goto this board.
ulimit -c 1800000
./1
# ./1
1
2
1
...
...
1
1: 1.c:37: main: Assertion `0' failed.
Aborted (core dumped)
Then you can get a core file.
gdb 1 core.xxx
Without the patch:
(gdb) info threads
 3 process 909  0x00000000 in ?? ()
 2 process 908  0x00000000 in ?? ()
* 1 process 907  0x4a6e2238 in raise () from /lib/libc.so.6
You can found that the pc of 909 and 908 is 0x00000000.
With the patch:
(gdb) info threads
 3 process 885  0x4a749974 in nanosleep () from /lib/libc.so.6
 2 process 884  0x4a749974 in nanosleep () from /lib/libc.so.6
* 1 process 883  0x4a6e2238 in raise () from /lib/libc.so.6
The pc of 885 and 884 is right.
Signed-off-by: NHui Zhu <teawater@gmail.com>
Cc: Amerigo Wang <xiyou.wangcong@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Jakub Jelinek <jakub@redhat.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I run many ffsb test cases on JBODs (typically 13/12 disks).  Comparing
with kernel 2.6.30, 2.6.31-rc1 has about 16% regression with
ffsb_create_4k.  The sub test case creates files continuously for 10
minitues and every file is 1MB.

Bisect located below patch.

5cee5815 is first bad commit
commit 5cee5815
Author: Jan Kara <jack@suse.cz>
Date:   Mon Apr 27 16:43:51 2009 +0200

    vfs: Make sys_sync() use fsync_super() (version 4)

    It is unnecessarily fragile to have two places (fsync_super() and do_sync())
    doing data integrity sync of the filesystem. Alter __fsync_super() to
    accommodate needs of both callers and use it. So after this patch
    __fsync_super() is the only place where we gather all the calls needed to
    properly send all data on a filesystem to disk.

As a matter of fact, ffsb calls sys_sync in the end to make sure all data
is flushed to disks and the flushing is counted into the result.  vmstat
shows ffsb is blocked when syncing for a long time.  With 2.6.30, ffsb is
blocked for a short time.

I checked the patch and did experiments to recover the original methods.
Eventually, the root cause is the patch deletes the calling to
wakeup_pdflush when syncing, so only ffsb is blocked on disk I/O.
wakeup_pdflush could ask pdflush to write back pages with ffsb at the
same time.

[akpm@linux-foundation.org: restore comment too]
Signed-off-by: NZhang Yanmin <yanmin_zhang@linux.intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: NJens Axboe <jens.axboe@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix for this issue on x86_64:

rostedt@goodmis.org wrote:
> On bootup of the latest kernel my init segfaults. Debugging it,
> I found  that vread_tsc (a vsyscall) increments some strange
> kernel memory:
>
> 0000000000000000 <vread_tsc>:
>    0:   55                      push   %rbp
>    1:   48 ff 05 00 00 00 00    incq   0(%rip)
>                         # 8 <vread_tsc+0x8>
>                         4: R_X86_64_PC32        .bss+0x3c
>    8:   48 89 e5                mov    %rsp,%rbp
>    b:   66 66 90                xchg   %ax,%ax
>    e:   48 ff 05 00 00 00 00    incq   0(%rip)
>                         # 15 <vread_tsc+0x15>
>                         11: R_X86_64_PC32       .bss+0x44
>   15:   66 66 90                xchg   %ax,%ax
>   18:   48 ff 05 00 00 00 00    incq   0(%rip)
>                         # 1f <vread_tsc+0x1f>
>                         1b: R_X86_64_PC32       .bss+0x4c
>   1f:   0f 31                   rdtsc
>
>
> Those "incq" is very bad to happen in vsyscall memory, since
> userspace can not modify it. You need to make something prevent
> profiling of vsyscall  memory (like I do with ftrace).
Signed-off-by: NPeter Oberparleiter <oberpar@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Reported-by: NSteven Rostedt <rostedt@goodmis.org>
Tested-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When i2c_smbus_read_byte_data fails in ds1374_work, we forgot to unlock
the held lock.  Fix that.
Signed-off-by: NJiri Slaby <jirislaby@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Scott Wood <scottwood@freescale.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix a typo in the VLYNQ bus driver Kconfig which prevented to turn on
VLYNQ bus debugging.
Signed-off-by: NFlorian Fainelli <florian@openwrt.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix a typo in the vlynq bus driver which was missing the CONFIG_ prefix to
turn on debugging code.
Signed-off-by: NRobert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: NFlorian Fainelli <florian@openwrt.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove redundant call to the sisfb_get_fix() before sis frambuffer is
registered.

This fixes a problem with uninitialized the fb_info->mm_lock mutex
introduced by the commit 537a1bf0 " fbdev: add mutex for fb_mmap
locking"
Signed-off-by: NKrzysztof Helt <krzysztof.h1@wp.pl>
Tested-by: NWu Zhangjin <wuzhangjin@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Our current strategy for pass-through mode is to put all devices into
the 1:1 domain at startup (which is before we know what their dma_mask
will be), and only _later_ take them out of that domain, if it turns out
that they really can't address all of memory.

However, when there are a bunch of PCI devices behind a bridge, they all
end up with the same source-id on their DMA transactions, and hence in
the same IOMMU domain. This means that we _can't_ easily move them from
the 1:1 domain into their own domain at runtime, because there might be DMA
in-flight from their siblings.

So we have to adjust our pass-through strategy: For PCI devices not on
the root bus, and for the bridges which will take responsibility for
their transactions, we have to start up _out_ of the 1:1 domain, just in
case.

This fixes the BUG() we see when we have 32-bit-capable devices behind a
PCI-PCI bridge, and use the software identity mapping.

It does mean that we might end up using 'normal' mapping mode for some
devices which could actually live with the faster 1:1 mapping -- but
this is only for PCI devices behind bridges, which presumably aren't the
devices for which people are most concerned about performance.
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

At boot time, the dma_mask won't have been set on any devices, so we
assume that all devices will be 64-bit capable (and thus get a 1:1 map).
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

Commit 537a1bf0 (fbdev: add mutex for
fb_mmap locking) introduces a ->mm_lock mutex for protecting smem
assignments. Unfortunately in the case of sm501fb these happen quite
early in the initialization code, well before the mutex_init() that takes
place in register_framebuffer(), leading to:

   Badness at kernel/mutex.c:207

   Pid : 1, Comm:          swapper
   CPU : 0                 Not tainted  (2.6.31-rc1-00284-g529ba0d9-dirty #2273)

   PC is at __mutex_lock_slowpath+0x72/0x1bc
   PR is at __mutex_lock_slowpath+0x66/0x1bc
   ...

matroxfb appears to have the same issue and has solved it with an early
mutex_init(), so we do the same for sm501fb.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>
Cc: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/kyle/parisc-2.6: (27 commits)
  parisc: use generic atomic64 on 32-bit
  parisc: superio: fix build breakage
  parisc: Fix PCI resource allocation on non-PAT SBA machines
  parisc: perf: wire up sys_perf_counter_open
  parisc: add task_pt_regs macro
  parisc: wire sys_perf_counter_open to sys_ni_syscall
  parisc: inventory.c, fix bloated stack frame
  parisc: processor.c, fix bloated stack frame
  parisc: fix compile warning in mm/init.c
  parisc: remove dead code from sys_parisc32.c
  parisc: wire up rt_tgsigqueueinfo
  parisc: ensure broadcast tlb purge runs single threaded
  parisc: fix "delay!" timer handling
  parisc: fix mismatched parenthesis in memcpy.c
  parisc: Fix gcc 4.4 warning in lba_pci.c
  parisc: add parameter to read_cr16()
  parisc: decode_exc.c should include kernel.h
  parisc: remove obsolete hw_interrupt_type
  parisc: fix irq compile bugs in arch/parisc/kernel/irq.c
  parisc: advertise PCI devs after "assign_resources"
  ...

Manually fixed up trivial conflicts in tools/perf/perf.h due to addition
of SH vs HPPA perf-counter support.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sameo/mfd-2.6:
  mfd: fix pcap adc locking
  mfd: sm501, fix lock imbalance

* 'for-2.6.31' of git://linux-nfs.org/~bfields/linux:
  NFSD: Don't hold unrefcounted creds over call to nfsd_setuser()

* 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus:
  MIPS: Fix CONFIG_FLATMEM version of pfn_valid()
  MIPS: Reorganize Cavium OCTEON PCI support.
  Update Yoichi Yuasa's e-mail address
  MIPS: Allow suspend and hibernation again on uniprocessor kernels.
  MIPS: 64-bit: Fix o32 core dump
  MIPS: BC47xx: Fix SSB irq setup
  MIPS: CMP: Update sync-r4k for current kernel
  MIPS: CMP: Move gcmp_probe to before the SMP ops
  MIPS: CMP: activate CMP support
  MIPS: CMP: Extend IPI handling to CPU number
  MIPS: CMP: Extend the GIC IPI interrupts beyond 32
  MIPS: Define __arch_swab64 for all mips r2 cpus
  MIPS: Update VR41xx GPIO driver to use gpiolib
  MIPS: Hookup new syscalls sys_rt_tgsigqueueinfo and sys_perf_counter_open.
  MIPS: Malta: Remove unnecessary function prototypes
  MIPS: MT: Remove unnecessary semicolons
  MIPS: Add support for Texas Instruments AR7 System-on-a-Chip

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
  sound: do not set DEVNAME for OSS devices
  ALSA: hda - Add sanity check in PCM open callback
  ALSA: hda - Call snd_pcm_lib_hw_rates() again after codec open callback
  ALSA: hda - Avoid invalid formats and rates with shared SPDIF
  ALSA: hda - Improve ASUS eeePC 1000 mixer
  ALSA: hda - Add GPIO1 control at muting with HP laptops
  ALSA: usx2y - reparent sound device
  ALSA: snd_usb_caiaq: reparent sound device
  sound: virtuoso: fix Xonar D1/DX silence after resume
  ASoC: Only disable pxa2xx-i2s clocks if we enabled them
  ALSA: hda - Add quirk for HP 6930p
  ALSA: hda - Add missing static to patch_ca0110()
  ASoC: OMAP: fix OMAP1510 broken PCM pointer callback
  ASoC: remove BROKEN from Efika and pcm030 fabric drivers
  ASoC: Fix typo in MPC5200 PSC AC97 driver Kconfig

* git://git.kernel.org/pub/scm/linux/kernel/git/sam/kbuild-fixes:
  kbuild: finally remove the obsolete variable $TOPDIR
  gitignore: ignore scripts/ihex2fw
  Kbuild: Disable the -Wformat-security gcc flag
  gitignore: ignore gcov output files
  kbuild: deb-pkg ship changelog
  Add new __init_task_data macro to be used in arch init_task.c files.
  asm-generic/vmlinux.lds.h: shuffle INIT_TASK* macro names in vmlinux.lds.h
  Add new macros for page-aligned data and bss sections.
  asm-generic/vmlinux.lds.h: Fix up RW_DATA_SECTION definition.

* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
  block: don't merge requests of different failfast settings
  cciss: Ignore stale commands after reboot

This should fix kernel.org bug #11821, where the dcdbas driver makes up
a platform device and then uses dma_alloc_coherent() on it, in an
attempt to get memory < 4GiB.
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

We need to give people a little more time to fix the broken drivers.
Re-introduce this, but tied in properly with the 'iommu=pt' support this
time. Change the config option name and make it default to 'no' too.
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

We do this twice, and it's about to get more complicated. This makes the
code slightly clearer about what it's doing, too.
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

When we reattach a device to the si_domain (because it's been removed
from a VM), we weren't calling domain_context_mapping() to actually tell
the hardware about that.

We should really put the call to domain_context_mapping() into
domain_add_dev_info() -- we never call the latter without also doing the
former, and we can keep the error paths simple that way. But that's a
cleanup which can wait for 2.6.32 now.
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

We should check iommu_dummy() _first_, because that means it's attached
to an iommu that we've just disabled completely. At the moment, we might
try to put the device into the identity mapping domain.
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

The aligned_nrpages() function rounds up to the next VM page, but
returns its result as a number of DMA pages.

Purely theoretical except on IA64, which doesn't boot with VT-d right
now anyway.
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

* fix/soundcore:
  sound: do not set DEVNAME for OSS devices

* fix/hda:
  ALSA: hda - Add sanity check in PCM open callback
  ALSA: hda - Call snd_pcm_lib_hw_rates() again after codec open callback
  ALSA: hda - Avoid invalid formats and rates with shared SPDIF
  ALSA: hda - Improve ASUS eeePC 1000 mixer
  ALSA: hda - Add GPIO1 control at muting with HP laptops

Signed-off-by: NKay Sievers <kay.sievers@vrfy.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

Add some sanity checks of struct snd_pcm_hardware fields in the PCM
open callback of hda driver.  This makes a bit easier to debug any PCM
setup errors in the codec side.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

The PCM rates bit field may have been changed by the codec open callback.
In that case, we need to reset rate_min and rate_max.  So, simply call
snd_pcm_lib_hw_rates() again after the codec open callback.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

Check whether formats and rates don't result in zero due to the
restriction of SPDIF sharing.  If any of them can be zero, disable
the SPDIF sharing mode instead.  Otherwise it will lead to a PCM
configuration error.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

Block layer used to merge requests and bios with different failfast
settings.  This caused regular IOs to fail prematurely when they were
merged into failfast requests for readahead.

Niel Lambrechts could trigger the problem semi-reliably on ext4 when
resuming from STR.  ext4 uses readahead when reading inodes and
combined with the deterministic extra SATA PHY exception cycle during
resume on the specific configuration, non-readahead inode read would
fail causing ext4 errors.  Please read the following thread for
details.

  http://lkml.org/lkml/2009/5/23/21

This patch makes block layer reject merging if the failfast settings
don't match.  This is correct but likely to lower IO performance by
preventing regular IOs from mingling into surrounding readahead
requests.  Changes to allow such mixed merges and handle errors
correctly will be added later.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NNiel Lambrechts <niel.lambrechts@gmail.com>
Cc: Theodore Tso <tytso@mit.edu>
Signed-off-by: NJens Axboe <axboe@carl.(none)>