For the initial architecture submission, not all of the DMA ops were
implemented.  This patch adds the *map_page and *map_sg variants of the
DMA mapping ops.

This patch is currently of interest mainly to some drivers that haven't
been submitted upstream yet.
Signed-off-by: NJonas Bonn <jonas@southpole.se>

As it was decided not to export struct pt_regs to userspace, struct
sigcontext shouldn't be using it either.  The pt_regs struct for OpenRISC
is kernel internal and the layout of the registers may change in the
future.  The struct user_regs_struct is what is guaranteed to remain
stable, so struct sigcontext may use that instead.

This patch removes the usage of struct pt_regs in struct sigcontext and
makes according changes in signal.c to get the register layout right.

The usp field is removed from the sigcontext structure as this information
is already contained in the user_regs_struct.
Signed-off-by: NJonas Bonn <jonas@southpole.se>
Reviewed-by: NEmilio Cota <cota@braap.org>

Commit db64fe02 ("mm: rewrite vmap layer") introduced code that does
address calculations under the assumption that VMAP_BLOCK_SIZE is a
power of two.  However, this might not be true if CONFIG_NR_CPUS is not
set to a power of two.

Wrong vmap_block index/offset values could lead to memory corruption.
However, this has never been observed in practice (or never been
diagnosed correctly); what caught this was the BUG_ON in vb_alloc() that
checks for inconsistent vmap_block indices.

To fix this, ensure that VMAP_BLOCK_SIZE always is a power of two.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=31572Reported-by: NPavel Kysilka <goldenfish@linuxsoft.cz>
Reported-by: NMatias A. Fonzo <selk@dragora.org>
Signed-off-by: NClemens Ladisch <clemens@ladisch.de>
Signed-off-by: NStefan Richter <stefanr@s5r6.in-berlin.de>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: 2.6.28+ <stable@kernel.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/cjb/mmc:
  mmc: remove unused "ddr" parameter in struct mmc_ios
  mmc: dw_mmc: Fix DDR mode support.
  mmc: core: use defined R1_STATE_PRG macro for card status
  mmc: sdhci: use f_max instead of host->clock for timeouts
  mmc: sdhci: move timeout_clk calculation farther down
  mmc: sdhci: check host->clock before using it as a denominator
  mmc: Revert "mmc: sdhci: Fix SDHCI_QUIRK_TIMEOUT_USES_SDCLK"
  mmc: tmio: eliminate unused variable 'mmc' warning
  mmc: esdhc-imx: fix card interrupt loss on freescale eSDHC
  mmc: sdhci-s3c: Fix build for header change
  mmc: dw_mmc: Fix mask in IDMAC_SET_BUFFER1_SIZE macro
  mmc: cb710: fix possible pci_dev leak in cb710_pci_configure()
  mmc: core: Detect eMMC v4.5 ext_csd entries
  mmc: mmc_test: avoid stalled file in debugfs
  mmc: sdhci-s3c: add BROKEN_ADMA_ZEROLEN_DESC quirk
  mmc: sdhci: pxav3: controller needs 32 bit ADMA addressing
  mmc: sdhci: fix retuning timer wrongly deleted in sdhci_tasklet_finish

* 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/staging:
  hwmon: (ibmaem) add missing kfree
  hwmon: (pmbus/lm25066) Ignore byte writes to non-zero pages
  hwmon: (pmbus) Virtualize pmbus_write_byte

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
  ASoC: Fix compile warning in wm8750.c
  ASoC: omap: Update e-mail address of Jarkko Nikula
  ASoC: SAMSUNG: Add I2S0 internal dma driver
  ASoC: Terminate WM8750 SPI device ID table
  ASoC: Add missing break in WM8994 probe
  ALSA: snd-usb-caiaq: Correct offset fields of outbound iso_frame_desc
  ALSA: azt3328 - adjust error handling code to include debugging code
  ALSA: hda - Add CONFIG_SND_HDA_POWER_SAVE to stac_vrefout_set()
  ALSA: usb-audio - Add quirk for BOSS Micro BR-80
  ASoC: Fix typo in wm8750 spi_ids
  ASoC: Fix warning in Speyside WM8962
  ASoC: Fix SPI driver binding for WM8987
  ASoC: Fix binding of WM8750 on Jive
  ASoC: WM8903: Free IRQ on device removal
  ASoC: Tegra: wm8903 machine driver: Allow re-insertion of module
  ASoC: Tegra: tegra_pcm_deallocate_dma_buffer: Don't OOPS

Remove the name of Sergey Kostyliov as maintainer of befs.
In the MAINTAINERS file, befs is orphaned.
Signed-off-by: NMarcos Souza <marcos.mage@gmail.com>
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Change resource URL to new git tree -
(http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git).
Signed-off-by: NRalf Thielow <ralf.thielow@googlemail.com>
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add a documentation file describing the usage of Ramoops
Signed-off-by: NSergiu Iordache <sergiu@chromium.org>
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add better Thunderbird information.
Add Thunderbird Registry instructions to:
  Enable UTF8 & Preformat mode
  Disable HTML mode
Signed-off-by: NPaul McQuade <paulmcquad@gmail.com>
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

General cleanups to kernel-parameters.txt:
 - add missing $ARCH that are being used/referenced
 - alphabetize the parameter restrictions list
 - spell "IA-64" as listed in arch/ia64/Kconfig instead of "IA64"
 - remove trailing whitespace
 - use hyphen in 32-bit etc.
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Usually kernel parameters are documented in kernel-parameters.txt
but user_debug is only documented in the Kconfig. Document the
option and point to the Kconfig help text for more info.
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Dropping LSD (Linux Source Driver) since it hasn't been available
for a long time.
Signed-off-by: NLuis de Bethencourt <luis@debethencourt.com>
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fixed a spelling error.
Signed-off-by: NZac Storer <zac.3.14159@gmail.com>
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

"mmc: dw_mmc: Fix DDR mode support" removed the last user.
Signed-off-by: NJaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

Host driver can't get a hint of DDR mode through ios->ddr flag anymore.
ios->timing is currently used to inform DDR mode as a substitute.
And capability of MMC_CAP_MMC_HIGHSPEED is added for DDR support.
Signed-off-by: NSeungwon Jeon <tgih.jun@samsung.com>
Acked-by: NWill Newton <will.newton@imgtec.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

Signed-off-by: NJaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

When timeout_clk is calculated the host->clock could be zero.
So, instead of host->clock the calculation now uses mmc->f_max.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

This moves the calculation below the assignment of mmc->f_max, which
we need for calculating timeout_clk in the next patch in this series.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

Sometimes host->clock could be zero which is a legal situation. This
patch checks host->clock before usage as a denominator when timeout is
calculated. A similar patch is applied for mmc core (see commit e9b86841,
"mmc: fix division by zero in MMC core").

Without this patch, the execution of the sdhci_calc_timeout could end up
with a backtrace:

<0>[    4.014319] divide error: 0000 [#1] PREEMPT SMP
<4>[    4.014352] Modules linked in: g_ether
<4>[    4.014376]
<4>[    4.014393] Pid: 33, comm: kworker/u:2 Not tainted 3.0.0+ #646
<4>[    4.014421] EIP: 0060:[<c12fa38e>] EFLAGS: 00010046 CPU: 1
<4>[    4.014449] EIP is at sdhci_calc_timeout+0x2e/0x100
<4>[    4.014468] EAX: 00000000 EBX: f5930fc8 ECX: 00000000 EDX: 00000000
<4>[    4.014488] ESI: f5291de8 EDI: f5291db8 EBP: f5291c6c ESP: f5291c50
<4>[    4.014508]  DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
<0>[    4.014529] Process kworker/u:2 (pid: 33, ti=f5290000 task=f53065a0 task.ti=f5290000)
<0>[    4.014546] Stack:
<4>[    4.014557]  00000082 c1054fdd f5291c78 04000000 f5930fc8 f5291de8 f5291db8 f5291cac
<4>[    4.014611]  c12fab7c c107a98b f5291c88 c13b6d3f f593109c f5882000 f5291cac c1054fdd
<4>[    4.014663]  00000000 00000000 f5882000 00000082 f5930fc8 f5291db8 0000000a f5291ccc
<0>[    4.014716] Call Trace:
<4>[    4.014743]  [<c1054fdd>] ? mod_timer+0x11d/0x380
<4>[    4.014770]  [<c12fab7c>] sdhci_prepare_data+0x2c/0x3a0
<4>[    4.014798]  [<c107a98b>] ? trace_hardirqs_off+0xb/0x10
<4>[    4.014827]  [<c13b6d3f>] ? _raw_spin_unlock_irqrestore+0x2f/0x60
<4>[    4.014854]  [<c1054fdd>] ? mod_timer+0x11d/0x380
<4>[    4.014880]  [<c12fc7db>] sdhci_send_command+0xdb/0x210
<4>[    4.014906]  [<c12fd5f3>] sdhci_request+0xc3/0x150
<4>[    4.014932]  [<c12ec56a>] mmc_start_request+0xda/0x200
<4>[    4.014960]  [<c120d7c2>] ? __raw_spin_lock_init+0x32/0x60
<4>[    4.014989]  [<c1066a85>] ? __init_waitqueue_head+0x35/0x50
<4>[    4.015015]  [<c12ec70b>] mmc_wait_for_req+0x7b/0x90
<4>[    4.015045]  [<c12f0c67>] mmc_send_cxd_data+0xf7/0x130
<4>[    4.015076]  [<c12ecbc0>] ? mmc_erase+0x140/0x140
<4>[    4.015102]  [<c12f139d>] mmc_send_ext_csd+0x1d/0x20
<4>[    4.015125]  [<c12efef0>] mmc_get_ext_csd+0x70/0x140
<4>[    4.015151]  [<c12effe8>] mmc_compare_ext_csds+0x28/0x190
<4>[    4.015176]  [<c12f039f>] mmc_init_card+0x24f/0x650
<4>[    4.015201]  [<c13b6d5d>] ? _raw_spin_unlock_irqrestore+0x4d/0x60
<4>[    4.015226]  [<c107fd9c>] ? trace_hardirqs_on_caller+0x11c/0x160
<4>[    4.015255]  [<c12f09a4>] mmc_attach_mmc+0xa4/0x190
<4>[    4.015282]  [<c12ee3f0>] mmc_rescan+0x210/0x240
<4>[    4.015311]  [<c105f9b6>] process_one_work+0x176/0x550
<4>[    4.015336]  [<c105f93a>] ? process_one_work+0xfa/0x550
<4>[    4.015360]  [<c12ee1e0>] ? mmc_init_erase+0x140/0x140
<4>[    4.015385]  [<c1061c2a>] worker_thread+0x12a/0x2c0
<4>[    4.015410]  [<c1061b00>] ? manage_workers.clone.18+0x100/0x100
<4>[    4.015437]  [<c1066244>] kthread+0x74/0x80
<4>[    4.015463]  [<c10661d0>] ? __init_kthread_worker+0x60/0x60
<4>[    4.015490]  [<c13b7dfa>] kernel_thread_helper+0x6/0xd
<0>[    4.015507] Code: 57 89 d7 56 53 89 c3 83 ec 10 8b 40 04 8b 72 28 f6 c4 10 89 45 f0 0f 85 91 00 00 00 85 f6 0f 84 c1 00 00 00 8b 4e 04 31 d2 89 c8 <f7> 73 58 ba d3 4d 62 10 89 c1 8b 06 f7 e2 c1 ea 06 01 d1 f7 45
<0>[    4.015829] EIP: [<c12fa38e>] sdhci_calc_timeout+0x2e/0x100 SS:ESP 0068:f5291c50
Reported-by: NAlexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

This reverts commit 4b01681c, which introduced a new potential
divide by zero in the process of fixing one.  The subsequent commits
attempt to fix the issue properly.
Signed-off-by: NChris Ball <cjb@laptop.org>

Fix below compile warning:
  CC      drivers/mmc/host/tmio_mmc.o
drivers/mmc/host/tmio_mmc.c: In function 'tmio_mmc_suspend':
drivers/mmc/host/tmio_mmc.c:30: warning: unused variable 'mmc'
drivers/mmc/host/tmio_mmc.c: In function 'tmio_mmc_resume':
drivers/mmc/host/tmio_mmc.c:45: warning: unused variable 'mmc'
Signed-off-by: NAxel Lin <axel.lin@gmail.com>
Acked-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: NChris Ball <cjb@laptop.org>

Apply a workaround for the imx eSDHC controller to avoid missing
card interrupts.  This makes SDIO work.
Signed-off-by: NTony Lin <tony.lin@freescale.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

A header change has removed an implicit inclusion of module.h, breaking
the build due to the use of THIS_MODULE. Fix that.
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

The mask used inside this macro was assuming Buffer_Size1's [BS1's]
width to be 14 bits, it is actually 13 bits.  Modify masks used in
IDMAC_SET_BUFFER1_SIZE such that they use only 13 bits instead of
current 14.
Signed-off-by: NShashidhar Hiremath <shashidharh@vayavyalabs.com>
Acked-by: NWill Newton <will.newton@imgtec.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

Reported-by: NJulia Lawall <julia@diku.dk>
Signed-off-by: NMichał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: NChris Ball <cjb@laptop.org>

The eMMC v4.5 Spec is released now:

EXT_CSD_REV	Extended CSD Revision
255-7		Reserved
6		Revision 1.6 (for MMC v4.5)
5		Revision 1.5 (for MMV v4.41)
...
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

During card removal and inserting cycle the test file in the debugfs could be
stalled until the host driver removes it. Let's keep the file in the linked
list and destroy it when card is removed.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: NPer Forlin <per.forlin@linaro.org>
Signed-off-by: NChris Ball <cjb@laptop.org>

Samsung SoCs need to set BROKEN_ADMA_ZEROLEN_DESC.
(If ADMA operation is more than 65535, maybe set by zero.)
Signed-off-by: NJaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

Enable the quirk.

(Best used in conjunction with patch downgrading ADMA to SDMA when
transfer is not aligned.)
Signed-off-by: NPhilip Rakity <prakity@marvell.com>
Acked-by: NZhangfei Gao <zhangfei.gao@marvell.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

Currently, the retuning timer for retuning mode 1 will be deleted in
function sdhci_tasklet_finish after a mmc request done, which will make
retuning timing never trigger again. This patch fixed this problem.
Signed-off-by: NAaron Lu <Aaron.Lu@amd.com>
Reviewed-by: NPhilip Rakity <prakity@marvell.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

* 'devicetree/merge' of git://git.secretlab.ca/git/linux-2.6:
  dt: add empty of_get_property for non-dt

* 'usb-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6: (30 commits)
  USB: Serial: Add PID(0xF7C0) to FTDI SIO driver for a zeitcontrol-device
  USB: Serial: Add device ID for Sierra Wireless MC8305
  USB: Serial: Added device ID for Qualcomm Modem in Sagemcom's HiLo3G
  usb/host/pci-quirks.c: correct annotation of `ehci_dmi_nohandoff_table'
  USB: option driver: add PID for Vodafone-Huawei K4511
  USB: option driver: add PID for Vodafone-Huawei K4510
  USB: option driver: add PID for Vodafone-Huawei K3771
  USB: option driver: add PID for Vodafone-Huawei K3770
  usb: serial: ftdi_sio.c: For the FT232H FTDI_SIO_SET_BAUDRATE_REQUEST, index needs to be shifted too
  usb/isp1760: Added missing call to usb_hcd_check_unlink_urb() during unlink
  USB: EHCI: Fix test mode sequence
  USB: ftdi_sio: fix minor typo in get_ftdi_divisor
  USB: at91_udc: include linux/prefetch.h explicitly
  USB: usb-storage: unusual_devs entry for ARM V2M motherboard.
  usb/ehci-mxc: add missing inclusion of mach/hardware.h
  USB: assign instead of equal in usbtmc.c
  usb: renesas_usbhs: fixup usbhsg_for_each_uep 1st pos
  usb: renesas_usbhs: fix DMA build by including dma-mapping.h
  usb: gadget: net2272 - Correct includes
  usb: musb: fix oops on musb_gadget_pullup
  ...

* 'staging-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging-2.6:
  zcache: Fix build error when sysfs is not defined
  zcache: Use div_u64 for 64-bit division
  staging:rts_pstor: fix thread synchronization flow
  drivers:staging:solo6x10:add the missed slab.h
  staging: zcache: include module.h for MODULE_LICENSE
  drivers/staging/hv/blkvsc_drv.c: eliminate NULL pointer dereference
  Staging: Add clk API note to nvec/TODO
  drivers/staging/ath6kl/miscdrv/ar3kps/ar3kpsparser.c: adjust array index
  staging: more missing slab.h inclusions
  drivers/staging/solo6x10/p2m.c needs slab.h
  drivers/staging/solo6x10/core.c needs slab.h
  drivers/staging/dt3155v4l/dt3155v4l.c needs slab.h
  drivers/staging/speakup/devsynth.c: fix "buffer size is not provably correct" error
  Staging: iio: add some unlocks to raw_read() functions
  staging: ft1000_proc needs asm/io.h for inw/outw on sparc
  staging: rtl8192u: declare MODULE_FIRMWARE
  gma500: Fix clashes with DRM updates
  staging: zcache: module is GPL
  staging: fix zcache building

* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-tip:
  x86-64: Rework vsyscall emulation and add vsyscall= parameter
  x86-64: Wire up getcpu syscall
  x86: Remove unnecessary compile flag tweaks for vsyscall code
  x86-64: Add vsyscall:emulate_vsyscall trace event
  x86-64: Add user_64bit_mode paravirt op
  x86-64, xen: Enable the vvar mapping
  x86-64: Work around gold bug 13023
  x86-64: Move the "user" vsyscall segment out of the data segment.
  x86-64: Pad vDSO to a page boundary

* 'for-linus' of git://oss.sgi.com/xfs/xfs:
  xfs: replace xfs_buf_geterror() with bp->b_error
  xfs: Check the return value of xfs_buf_read() for NULL
  "xfs: fix error handling for synchronous writes" revisited
  xfs: set cursor in xfs_ail_splice() even when AIL was empty
  xfs: Remove the macro XFS_BUFTARG_NAME
  xfs: Remove the macro XFS_BUF_TARGET
  xfs: Remove the macro XFS_BUF_SET_TARGET
  Replace the macro XFS_BUF_ISPINNED with helper xfs_buf_ispinned
  xfs: Remove the macro XFS_BUF_SET_PTR
  xfs: Remove the macro XFS_BUF_PTR
  xfs: Remove macro XFS_BUF_SET_START
  xfs: Remove macro XFS_BUF_HOLD
  xfs: Remove macro XFS_BUF_BUSY and family
  xfs: Remove the macro XFS_BUF_ERROR and family
  xfs: Remove the macro XFS_BUF_BFLAGS

* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/linux-arm-soc: (32 commits)
  ARM: mmp: Change the way we use timer 0 as clockevent timer.
  ARM: mmp: Switch to using timer 1 as clocksource timer.
  ARM: mmp: Also start timer 1 on boot.
  ARM: pxa168/gplugd: free correct GPIO
  ARM: pxa168/gplugd: get rid of mfp-gplugd.h
  ARM: pxa: fix logic error in PJ4 iWMMXt handling
  mach-sa1100: fix PCI build problem
  omap: timer: Set dmtimer used as clocksource in autoreload mode
  OMAP3: am3517crane: remove NULL board_mux from board file
  arm: mach-omap2: mux: use kstrdup()
  arch:arm:plat-omap:iovmm: remove unused variable 'va'
  Update Nook Color machine 3284 to common Encore name
  am3505/3517: Various platform defines for UART4
  OMAP: hwmod: fix build break on non-OMAP4 multi-OMAP2 builds
  OMAP: Fix linking error in twl-common.c for OMAP2/3/4 only builds
  iMX: Fix build for iMX53
  ARM: mx5: board-cpuimx51.c fixup irq_to_gpio() usage
  OMAP2+: PM: SmartReflex: use put_sync_suspend for IRQ-safe disabling
  OMAP3: beagle: don't touch omap_device internals
  OMAP1: enable GENERIC_IRQ_CHIP
  ...

Since we just checked bp for NULL, it is ok to replace
xfs_buf_geterror() with bp->b_error in these places.
Signed-off-by: NChandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: NAlex Elder <aelder@sgi.com>

Check the return value of xfs_buf_read() for NULL and return ENOMEM
if it is NULL.  This is necessary in a few spots to avoid subsequent
code blindly dereferencing the null buffer pointer.
Signed-off-by: NChandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: NAlex Elder <aelder@sgi.com>