When a raid1 array is configured to support write-behind
on some devices, it normally only reads from other devices.
If all devices are write-behind (because the rest have failed)
it is possible for a read request to be serviced before a
behind-write request, which would appear as data corruption.

So when forced to read from a WriteMostly device, wait for any
write-behind to complete, and don't start any more behind-writes.
Signed-off-by: NeilBrown <neilb@suse.de>

This message seems to suggest the named device is the one on which a
read failed, however it is actually the device that the read will be
redirected to.
So make the message a little clearer.
Reported-by: Tim Burgess <ozburgess@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>

This is
 - unnecessary because mddev_suspend is always followed by a call to
   ->stop, and each ->stop unregisters the thread, and
 - a problem as it makes it awkwards to suspend and then resume a
   device as we will want later.
Signed-off-by: NeilBrown <neilb@suse.de>

This is a simple factorisation that makes mddev_find easier to read.
Signed-off-by: NeilBrown <neilb@suse.de>

We used to pass the personality make_request function direct
to the block layer so the first argument had to be a queue.
But now we have the intermediary md_make_request so it makes
at lot more sense to pass a struct mddev_s.
It makes it possible to have an mddev without its own queue too.
Signed-off-by: NeilBrown <neilb@suse.de>

This moves the call to the other side of set_readonly, but that should
not be an issue.
This encapsulates in 'md_stop' all of the functionality for internally
stopping the array, leaving all the interactions with externalities
(sysfs, request_queue, gendisk) in do_md_stop.
Signed-off-by: NeilBrown <neilb@suse.de>

Using do_md_stop to set an array to read-only is a little confusing.
Now most of the common code has been factored out, split
md_set_readonly off in to a separate function.
Signed-off-by: NeilBrown <neilb@suse.de>

Further refactoring of do_md_stop.
This one requires some explanation as it takes code from different
places in do_md_stop, so some re-ordering happens.

We only get into this part of do_md_stop if there are no active opens
of the device, so no writes can be happening and the device must have
been flushed.  In md_stop_writes we want to stop any internal sources
of writes - i.e. resync - and flush out the metadata.

The only code that was previously before some of this code is
code to clean up the queue, the mddev, the gendisk, or sysfs, all
of which is probably better after code that makes active changes (i.e.
triggers writes).
Signed-off-by: NeilBrown <neilb@suse.de>

do_md_stop is large and clunky, so hard to understand.

This is a first step of refactoring, pulling two simple
sub-functions out.
Signed-off-by: NeilBrown <neilb@suse.de>

As part of relaxing the binding between an mddev and gendisk,
we separate do_md_run into two functions.
  md_run does all the work internal to md
  do_md_run calls md_run and makes and changes to gendisk
     that are required.
Signed-off-by: NeilBrown <neilb@suse.de>

We set ->changed to 1 and call check_disk_change at the end
of md_open so that bd_invalidated would be set and thus
partition rescan would happen appropriately.

Now that we call revalidate_disk directly, which sets bd_invalidates,
that indirection is no longer needed and can be removed.
Signed-off-by: NeilBrown <neilb@suse.de>

Using ->array_sectors rather than get_capacity() is more
direct and is a step towards relaxing the tight connection
between mddev and gendisk.
Signed-off-by: NeilBrown <neilb@suse.de>

While I generally prefer letting personalities do as much as possible,
given that we have a central md_make_request anyway we may as well use
it to simplify code.
Also this centralises knowledge of ->gendisk which will help later.
Signed-off-by: NeilBrown <neilb@suse.de>

Diving through ->queue to find mddev is unnecessarily complex - there
is an easier path to finding mddev, so use that.
Signed-off-by: NeilBrown <neilb@suse.de>

This is unlikely to be wanted, but we may as well provide it
for completeness.
Signed-off-by: NeilBrown <neilb@suse.de>

Level changes can be very significant, so make sure
to notify them via sysfs.
Signed-off-by: Maciej Trela <maciej.trela@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

When metadata is being managed by user-space, md doesn't know
what the maximum number of devices allowed in an array is
so ->max_disks is 0.  In this case we should allow any (+ve)
number of disks.
Signed-off-by: NeilBrown <neilb@suse.de>

Writing "none" to "../md/dev-xx/slot" removes that device
from being an active part of the array, but it didn't
set ->raid_disk to -1 to record this fact.
Signed-off-by: Maciej Trela <Maciej.Trela@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

Signed-off-by: Maciej Trela <maciej.trela@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

Signed-off-by: Maciej Trela <maciej.trela@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

Signed-off-by: Maciej Trela <maciej.trela@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

In a subsequent patch we will make it possible to change
mddev->raid_disks while a RAID0 or RAID10 array is active.  This is
part of the process of reshaping such an array.

This means that we cannot use this value while processes requests
(it is OK to use it during initialisation as we are locked against
changes then).
Both RAID0 and RAID10 have the same value stored in the private data
structure, so use that value instead.
Signed-off-by: NeilBrown <neilb@suse.de>

This was needed when sysfs files could only be 'notified'
from process context.  Now that we have sys_notify_direct,
we can call it directly from an interrupt.
Signed-off-by: NeilBrown <neilb@suse.de>

void pointers do not need to be cast to other pointer types.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: NeilBrown <neilb@suse.de>

Keep track of the maximum number of concurrent write-behind requests
for an md array and exposed this number in sysfs at
   md/bitmap/max_backlog_used

Writing any value to this file will clear it.

This allows userspace to be involved in tuning bitmap/backlog.
Signed-off-by: Paul Clements <paul.clements@steeleye.com>
Signed-off-by: NeilBrown <neilb@suse.de>

These fields have never been used.
commit 4b6d287f
added them, but also added identical files to bitmap_super_s,
and only used the latter.

So remove these unused fields.
Signed-off-by: NeilBrown <neilb@suse.de>

There is a very small race window when writing to a
RAID1 such that if a device is marked faulty at exactly the wrong
time, the write-in-progress will not be sent to the device,
but the bitmap (if present) will be updated to say that
the write was sent.

Then if the device turned out to still be usable as was re-added
to the array, the bitmap-based-resync would skip resyncing that
block, possibly leading to corruption.  This would only be a problem
if no further writes were issued to that area of the device (i.e.
that bitmap chunk).

Suitable for any pending -stable kernel.

Cc: stable@kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>

Some levels expect the 'redundancy group' to be present,
others don't.
So when we change level of an array we might need to
add or remove this group.

This requires fixing up the current practice of overloading ->private
to indicate (when ->pers == NULL) that something needs to be removed.
So create a new ->to_remove to fill that role.

When changing levels, we may need to add or remove attributes.  When
changing RAID5 -> RAID6, we both add and remove the same thing.  It is
important to catch this and optimise it out as the removal is delayed
until a lock is released, so trying to add immediately would cause
problems.


Cc: stable@kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>

When an array is stopped we need to remove some
sysfs files which are dependent on the type of array.

We need to delay that deletion as deleting them while holding
reconfig_mutex can lead to deadlocks.

We currently delay them until the array is completely destroyed.
However it is possible to deactivate and then reactivate the array.
It is also possible to need to remove sysfs files when changing level,
which can potentially happen several times before an array is
destroyed.

So we need to delete these files more promptly: as soon as
reconfig_mutex is dropped.

We need to ensure this happens before do_md_run can restart the array,
so we use open_mutex for some extra locking.  This is not deadlock
prone.

Cc: stable@kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>

Since commit ef286f6f
it has been important that each personality clears
->private in the ->stop() function, or sets it to a
attribute group to be removed.
linear.c doesn't.  This can sometimes lead to an oops,
though it doesn't always.

Suitable for 2.6.33-stable and 2.6.34.
Signed-off-by: NeilBrown <neilb@suse.de>
Cc: stable@kernel.org

When the user sets the block device to readwrite then the mddev should
follow suit.  Otherwise, the BUG_ON in md_write_start() will be set to
trigger.

The reverse direction, setting mddev->ro to match a set readonly
request, can be ignored because the blkdev level readonly flag precludes
the need to have mddev->ro set correctly.  Nevermind the fact that
setting mddev->ro to 1 may fail if the array is in use.

Cc: <stable@kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

If a component device has a merge_bvec_fn then as we never call it
we must ensure we never need to.  Currently this is done by setting
max_sector to 1 PAGE, however this does not stop a bio being created
with several sub-page iovecs that would violate the merge_bvec_fn.

So instead set max_segments to 1 and set the segment boundary to the
same as a page boundary to ensure there is only ever one single-page
segment of IO requested at a time.

This can particularly be an issue when 'xen' is used as it is
known to submit multiple small buffers in a single bio.
Signed-off-by: NeilBrown <neilb@suse.de>
Cc: stable@kernel.org

* git://git.kernel.org/pub/scm/linux/kernel/git/amit/virtio-console:
  virtio: console: Use better variable names for fill_queue operation
  virtio: console: Fix type of 'len' as unsigned int

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

* 'x86-mrst-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (30 commits)
  x86, mrst: Fix whitespace breakage in apb_timer.c
  x86, mrst: Fix APB timer per cpu clockevent
  x86, mrst: Remove X86_MRST dependency on PCI_IOAPIC
  x86, olpc: Use pci subarch init for OLPC
  x86, pci: Add arch_init to x86_init abstraction
  x86, mrst: Add Kconfig dependencies for Moorestown
  x86, pci: Exclude Moorestown PCI code if CONFIG_X86_MRST=n
  x86, numaq: Make CONFIG_X86_NUMAQ depend on CONFIG_PCI
  x86, pci: Add sanity check for PCI fixed bar probing
  x86, legacy_irq: Remove duplicate vector assigment
  x86, legacy_irq: Remove left over nr_legacy_irqs
  x86, mrst: Platform clock setup code
  x86, apbt: Moorestown APB system timer driver
  x86, mrst: Add vrtc platform data setup code
  x86, mrst: Add platform timer info parsing code
  x86, mrst: Fill in PCI functions in x86_init layer
  x86, mrst: Add dummy legacy pic to platform setup
  x86/PCI: Moorestown PCI support
  x86, ioapic: Add dummy ioapic functions
  x86, ioapic: Early enable ioapic for timer irq
  ...

Fixed up semantic conflict of new clocksources due to commit
17622339 ("clocksource: add argument to resume callback").

* 'for-linus/i2c' of git://git.fluff.org/bjdooks/linux:
  i2c: Add support for Xilinx XPS IIC Bus Interface
  i2c: omap: Add support for 16-bit registers
  i2c-pnx: fix setting start/stop condition
  powerpc: doc/dts-bindings: update doc of FSL I2C bindings
  i2c-mpc: add support for the MPC512x processors from Freescale
  i2c-mpc: rename "setclock" initialization functions to "setup"
  i2c-mpc: use __devinit[data] for initialization functions and data
  i2c/imx: don't add probe function to the driver struct
  i2c: Add support for Ux500/Nomadik I2C controller

* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/sameo/mfd-2.6: (66 commits)
  mfd: Fix ucb1x00 build failure for collie_defconfig
  mfd: Fix lpc_sch related depends/selects, fix build error
  gpio: Fix sch_gpio warning
  gpio: add Intel SCH GPIO controller driver
  i2c: convert i2c-isch to platform_device
  mfd: Use completion interrupt for WM831x AUXADC
  mfd: Use completion interrupt for WM835x AUXADC
  mfd: Introduce remove_script function for twl4030
  mfd/mmc: SDHI Kconfig update
  mfd: sh_mobile_sdhi MMC_CAP_MMC_HIGHSPEED support
  gpiolib: Force wm831x GPIOs into GPIO mode when requested
  mfd: Add WM831x revision B support
  gpiolib: Correct debugfs display of WM831x GPIO inversion
  gpiolib: Actually set output state in wm831x_gpio_direction_output()
  tmio_mmc: Balance cell enable()/disable() calls
  tmio_mmc: Remove const from platform data V3
  tmio_mmc: Use 100ms mmc_detect_change() delay
  tmio_mmc: Add MMC_CAP_MMC_HIGHSPEED support V2
  tmio_mmc: Keep card-detect interrupts enabled
  mfd: Add twl6030 base addr for ID0, ID1, ID2
  ...

* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging-2.6: (368 commits)
  Staging: winbond: fix up wireless api errors
  Staging: dream: camera: sk5k3e2fx: fix code style issues
  Staging: dream: camera: msm_camera: fix code style issues
  Staging: wlan-ng: More checkpatch.pl error cleanups
  Staging: wlan-ng - checkpatch.pl fixups
  Staging: comedi: comedi_fops.c: Checkpatch cleanup
  Staging: comedi: fix suspect code indent in ni_labpc.c
  Staging: comedi: fix yet another brace coding style issue in ni_labpc.c
  Staging: comedi: fix another brace coding style issues in ni_labpc.c
  Staging: comedi: fix brace coding style issue in ni_labpc.c
  Staging: comedi: poc: Adding some KERN_ facility level
  Staging: dream: camera: msm_camera: fix some code style issues
  Staging: wlan-ng: fix most of the style issues in hfa384x.h
  Staging: dream: camera: msm_camera: fix coding style issues
  Staging: comedi: fix bracing coding style and 80 character issues in ni_660x.c
  Staging: comedi: fix bracing coding style issue in ni_65xx.c
  Staging: comedi: pcmad: Checkpatch cleanups
  Staging: comedi: poc: fix coding style issues
  staging: dt3155: revert u_long to u64 usage
  Staging: comedi: drivers.c: Checkpatch cleanup
  ...

Fix kernel-doc notation in new seq-file functions and
correct spelling.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6: (26 commits)
  sh: Convert sh to use read/update_persistent_clock
  sh: Move PMB debugfs entry initialization to later stage
  sh: Fix up flush_cache_vmap() on SMP.
  sh: fix up MMU reset with variable PMB mapping sizes.
  sh: establish PMB mappings for NUMA nodes.
  sh: check for existing mappings for bolted PMB entries.
  sh: fixed virt/phys mapping helpers for PMB.
  sh: make pmb iomapping configurable.
  sh: reworked dynamic PMB mapping.
  sh: Fix up cpumask_of_pcibus() for the NUMA build.
  serial: sh-sci: Tidy up build warnings.
  sh: Fix up ctrl_read/write stragglers in migor setup.
  serial: sh-sci: Add DMA support.
  dmaengine: shdma: extend .device_terminate_all() to record partial transfer
  sh: merge sh7722 and sh7724 DMA register definitions
  sh: activate runtime PM for dmaengine on sh7722 and sh7724
  dmaengine: shdma: add runtime PM support.
  dmaengine: shdma: separate DMA headers.
  dmaengine: shdma: convert to platform device resources
  dmaengine: shdma: fix DMA error handling.
  ...

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/kyle/parisc-2.6:
  parisc: use __ratelimit in unaligned.c
  parisc: Convert to read/update_persistent_clock
  parisc: Simplify param.h by including <asm-generic/param.h>
  parisc: drop unnecessary cast in __ldcw_align() macro
  parisc: add strict copy size checks (v2)
  parisc: remove trailing space in messages
  parisc: ditto sys_accept4
  parisc: wire up sys_recvmmsg