v3: s-o-b comment, explanation of performance and descision for
the start/stop implementation

Implementing rmw functionality for RAID6 requires optimized syndrome
calculation. Up to now we can only generate a complete syndrome. The
target P/Q pages are always overwritten. With this patch we provide
a framework for inplace P/Q modification. In the first place simply
fill those functions with NULL values.

xor_syndrome() has two additional parameters: start & stop. These
will indicate the first and last page that are changing during a
rmw run. That makes it possible to avoid several unneccessary loops
and speed up calculation. The caller needs to implement the following
logic to make the functions work.

1) xor_syndrome(disks, start, stop, ...): "Remove" all data of source
blocks inside P/Q between (and including) start and end.

2) modify any block with start <= block <= stop

3) xor_syndrome(disks, start, stop, ...): "Reinsert" all data of
source blocks into P/Q between (and including) start and end.

Pages between start and stop that won't be changed should be filled
with a pointer to the kernel zero page. The reasons for not taking NULL
pages are:

1) Algorithms cross the whole source data line by line. Thus avoid
additional branches.

2) Having a NULL page avoids calculating the XOR P parity but still
need calulation steps for the Q parity. Depending on the algorithm
unrolling that might be only a difference of 2 instructions per loop.

The benchmark numbers of the gen_syndrome() functions are displayed in
the kernel log. Do the same for the xor_syndrome() functions. This
will help to analyze performance problems and give an rough estimate
how well the algorithm works. The choice of the fastest algorithm will
still depend on the gen_syndrome() performance.

With the start/stop page implementation the speed can vary a lot in real
life. E.g. a change of page 0 & page 15 on a stripe will be harder to
compute than the case where page 0 & page 1 are XOR candidates. To be not
to enthusiatic about the expected speeds we will run a worse case test
that simulates a change on the upper half of the stripe. So we do:

1) calculation of P/Q for the upper pages

2) continuation of Q for the lower (empty) pages
Signed-off-by: Markus Stockhausen <stockhausen@collogia.de>
Signed-off-by: NeilBrown <neilb@suse.de>

expansion/resync can grab a stripe when the stripe is in batch list. Since all
stripes in batch list must be in the same state, we can't allow some stripes
run into expansion/resync. So we delay expansion/resync for stripe in batch
list.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>

If io error happens in any stripe of a batch list, the batch list will be
split, then normal process will run for the stripes in the list.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>

stripe cache is 4k size. Even adjacent full stripe writes are handled in 4k
unit. Idealy we should use big size for adjacent full stripe writes. Bigger
stripe cache size means less stripes runing in the state machine so can reduce
cpu overhead. And also bigger size can cause bigger IO size dispatched to under
layer disks.

With below patch, we will automatically batch adjacent full stripe write
together. Such stripes will be added to the batch list. Only the first stripe
of the list will be put to handle_list and so run handle_stripe(). Some steps
of handle_stripe() are extended to cover all stripes of the list, including
ops_run_io, ops_run_biodrain and so on. With this patch, we have less stripes
running in handle_stripe() and we send IO of whole stripe list together to
increase IO size.

Stripes added to a batch list have some limitations. A batch list can only
include full stripe write and can't cross chunk boundary to make sure stripes
have the same parity disks. Stripes in a batch list must be in the same state
(no written, toread and so on). If a stripe is in a batch list, all new
read/write to add_stripe_bio will be blocked to overlap conflict till the batch
list is handled. The limitations will make sure stripes in a batch list be in
exactly the same state in the life circly.

I did test running 160k randwrite in a RAID5 array with 32k chunk size and 6
PCIe SSD. This patch improves around 30% performance and IO size to under layer
disk is exactly 32k. I also run a 4k randwrite test in the same array to make
sure the performance isn't changed with the patch.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>

Track overwrite disk count, so we can know if a stripe is a full stripe write.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>

A freshly new stripe with write request can be batched. Any time the stripe is
handled or new read is queued, the flag will be cleared.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>

Use flex_array for scribble data. Next patch will batch several stripes
together, so scribble data should be able to cover several stripes, so this
patch also allocates scribble data for stripes across a chunk.
Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: NeilBrown <neilb@suse.de>

md raid0: access mddev->queue (request queue member) conditionally because it is not set when accessed from dm-raid

The patch makes 3 references to mddev->queue in the raid0 personality
conditional in order to allow for it to be accessed from dm-raid.
Mandatory, because md instances underneath dm-raid don't manage
a request queue of their own which'd lead to oopses without the patch.
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Tested-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>

When md notices non-sync IO happening while it is trying
to resync (or reshape or recover) it slows down to the
set minimum.

The default minimum might have made sense many years ago
but the drives have become faster.  Changing the default
to match the times isn't really a long term solution.

This patch changes the code so that instead of waiting until the speed
has dropped to the target, it just waits until pending requests
have completed.
This means that the delay inserted is a function of the speed
of the devices.

Testing shows that:
 - for some loads, the resync speed is unchanged.  For those loads
   increasing the minimum doesn't change the speed either.
   So this is a good result.  To increase resync speed under such
   loads we would probably need to increase the resync window
   size.

 - for other loads, resync speed does increase to a reasonable
   fraction (e.g. 20%) of maximum possible, and throughput of
   the load only drops a little bit (e.g. 10%)

 - for other loads, throughput of the non-sync load drops quite a bit
   more.  These seem to be latency-sensitive loads.

So it isn't a perfect solution, but it is mostly an improvement.
Signed-off-by: NeilBrown <neilb@suse.de>

This option is not well justified and testing suggests that
it hardly ever makes any difference.

The comment suggests there might be a need to wait for non-resync
activity indicated by ->nr_waiting, however raise_barrier()
already waits for all of that.

So just remove it to simplify reasoning about speed limiting.

This allows us to remove a 'FIXME' comment from raid5.c as that
never used the flag.
Signed-off-by: NeilBrown <neilb@suse.de>

There is really no need for sync_min to be a multiple of
chunk_size, and values read from here often aren't.
That means you cannot read a value and expect to be able
to write it back later.

So remove the chunk_size check, and round down to a multiple
of 4K, to be sure everything works with 4K-sector devices.
Signed-off-by: NeilBrown <neilb@suse.de>

When "re-add" is writted to /sys/block/mdXX/md/dev-YYY/state,
the clustered md:

1. Sends RE_ADD message with the desc_nr. Nodes receiving the message
   clear the Faulty bit in their respective rdev->flags.
2. The node initiating re-add, gathers the bitmaps of all nodes
   and copies them into the local bitmap. It does not clear the bitmap
   from which it is copying.
3. Initiating node schedules a md recovery to sync the devices.
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NeilBrown <neilb@suse.de>

This adds the capability of re-adding a failed disk by
writing "re-add" to /sys/block/mdXX/md/dev-YYY/state.

This facilitates adding disks which have encountered a temporary
error such as a network disconnection/hiccup in an iSCSI device,
or a SAN cable disconnection which has been restored. In such
a situation, you do not need to remove and re-add the device.
Writing re-add to the failed device's state would add it again
to the array and perform the recovery of only the blocks which
were written after the device failed.

This works for generic md, and is not related to clustering. However,
this patch is to ease re-add operations listed above in clustering
environments.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NeilBrown <neilb@suse.de>

This adds "remove" capabilities for the clustered environment.
When a user initiates removal of a device from the array, a
REMOVE message with disk number in the array is sent to all
the nodes which kick the respective device in their own array.

This facilitates the removal of failed devices.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NeilBrown <neilb@suse.de>

This is required by the clustering module (patches to follow) to
find the device to remove or re-add.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NeilBrown <neilb@suse.de>

This export is required for clustering module in order to
co-ordinate remove/readd a rdev from all nodes.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NeilBrown <neilb@suse.de>

Since the node num of md-cluster is from zero, and
cinfo->slot_number represents the slot num of dlm,
no need to check for equality.
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NeilBrown <neilb@suse.de>

Since commit 20d0189b
in v3.14-rc1 RAID0 has performed incorrect calculations
when the chunksize is not a power of 2.

This happens because "sector_div()" modifies its first argument, but
this wasn't taken into account in the patch.

So restore that first arg before re-using the variable.
Reported-by: Joe Landman <joe.landman@gmail.com>
Reported-by: Dave Chinner <david@fromorbit.com>
Fixes: 20d0189b
Cc: stable@vger.kernel.org (3.14 and later).
Signed-off-by: NeilBrown <neilb@suse.de>

Simon reported the md io stats accounting issue:
"
I'm seeing "iostat -x -k 1" print this after a RAID1 rebuild on 4.0-rc5.
It's not abnormal other than it's 3-disk, with one being SSD (sdc) and
the other two being write-mostly:

Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
sda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
sdb               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
sdc               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
md0               0.00     0.00    0.00    0.00     0.00     0.00     0.00   345.00    0.00    0.00    0.00   0.00 100.00
md2               0.00     0.00    0.00    0.00     0.00     0.00     0.00 58779.00    0.00    0.00    0.00   0.00 100.00
md1               0.00     0.00    0.00    0.00     0.00     0.00     0.00    12.00    0.00    0.00    0.00   0.00 100.00
"
The cause is commit "18c0b223" uses the
generic_start_io_acct to account the disk stats rather than the open code,
but it also introduced the increase to .in_flight[rw] which is needless to
md. So we re-use the open code here to fix it.
Reported-by: Simon Kirby <sim@hostway.ca>
Cc: <stable@vger.kernel.org> 3.19
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: NeilBrown <neilb@suse.de>

Pull networking fixes from David Miller:

 1) In TCP, don't register an FRTO for cumulatively ACK'd data that was
    previously SACK'd, from Neal Cardwell.

 2) Need to hold RNL mutex in ipv4 multicast code namespace cleanup,
    from Cong WANG.

 3) Similarly we have to hold RNL mutex for fib_rules_unregister(), also
    from Cong WANG.

 4) Revert and rework netns nsid allocation fix, from Nicolas Dichtel.

 5) When we encapsulate for a tunnel device, skb->sk still points to the
    user socket.  So this leads to cases where we retraverse the
    ipv4/ipv6 output path with skb->sk being of some other address
    family (f.e. AF_PACKET).  This can cause things to crash since the
    ipv4 output path is dereferencing an AF_PACKET socket as if it were
    an ipv4 one.

    The short term fix for 'net' and -stable is to elide these socket
    checks once we've entered an encapsulation sequence by testing
    xmit_recursion.

    Longer term we have a better solution wherein we pass the tunnel's
    socket down through the output paths, but that is way too invasive
    for 'net' and -stable.

    From Hannes Frederic Sowa.

 6) l2tp_init() failure path forgets to unregister per-net ops, from
    Cong WANG.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net:
  net/mlx4_core: Fix error message deprecation for ConnectX-2 cards
  net: dsa: fix filling routing table from OF description
  l2tp: unregister l2tp_net_ops on failure path
  mvneta: dont call mvneta_adjust_link() manually
  ipv6: protect skb->sk accesses from recursive dereference inside the stack
  netns: don't allocate an id for dead netns
  Revert "netns: don't clear nsid too early on removal"
  ip6mr: call del_timer_sync() in ip6mr_free_table()
  net: move fib_rules_unregister() under rtnl lock
  ipv4: take rtnl_lock and mark mrt table as freed on namespace cleanup
  tcp: fix FRTO undo on cumulative ACK of SACKed range
  xen-netfront: transmit fully GSO-sized packets

Commit 1daa4303 ("net/mlx4_core: Deprecate error message at
ConnectX-2 cards startup to debug") did the deprecation only for port 1
of the card. Need to deprecate for port 2 as well.

Fixes: 1daa4303 ("net/mlx4_core: Deprecate error message at ConnectX-2 cards startup to debug")
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

According to description in 'include/net/dsa.h', in cascade switches
configurations where there are more than one interconnected devices,
'rtable' array in 'dsa_chip_data' structure is used to indicate which
port on this switch should be used to send packets to that are destined
for corresponding switch.

However, dsa_of_setup_routing_table() fills 'rtable' with port numbers
of the _target_ switch, but not current one.

This commit removes redundant devicetree parsing and adds needed port
number as a function argument. So dsa_of_setup_routing_table() now just
looks for target switch number by parsing parent of 'link' device node.

To remove possible misunderstandings with the way of determining target
switch number, a corresponding comment was added to the source code and
to the DSA device tree bindings documentation file.

This was tested on a custom board with two Marvell 88E6095 switches with
following corresponding routing tables: { -1, 10 } and { 8, -1 }.
Signed-off-by: Pavel Nakonechny <pavel.nakonechny@skitlab.ru>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Pull input fixes from Dmitry Torokhov:
 "Updates for the input subsystem - two more tweaks for ALPS driver to
  work out kinks after splitting the touchpad, trackstick, and potential
  external PS/2 mouse into separate input devices.

  Changes to support ALPS SS4 devices (protocol V8) will be coming in
  4.1..."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: alps - document stick behavior for protocol V2
  Input: alps - report V2 Dualpoint Stick events via the right evdev node
  Input: alps - report interleaved bare PS/2 packets via dev3

Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mvneta_adjust_link() is a callback for of_phy_connect() and should
not be called directly. The result of calling it directly is as below:
Signed-off-by: David S. Miller <davem@davemloft.net>

We should not consult skb->sk for output decisions in xmit recursion
levels > 0 in the stack. Otherwise local socket settings could influence
the result of e.g. tunnel encapsulation process.

ipv6 does not conform with this in three places:

1) ip6_fragment: we do consult ipv6_npinfo for frag_size

2) sk_mc_loop in ipv6 uses skb->sk and checks if we should
   loop the packet back to the local socket

3) ip6_skb_dst_mtu could query the settings from the user socket and
   force a wrong MTU

Furthermore:
In sk_mc_loop we could potentially land in WARN_ON(1) if we use a
PF_PACKET socket ontop of an IPv6-backed vxlan device.

Reuse xmit_recursion as we are currently only interested in protecting
tunnel devices.

Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Document that protocol V2 uses standard (bare) PS/2 mouse packets for the
DualPoint stick.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-By: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

On V2 devices the DualPoint Stick reports bare packets, these should be
reported via the "AlpsPS/2 ALPS DualPoint Stick" dev2 evdev node, which also
has the INPUT_PROP_POINTING_STICK propbit set.

Note that since there is no way to distinguish these packets from an external
PS/2 mouse (insofar as these laptops have an external PS/2 port) this means
that we will be reporting PS/2 mouse events via this evdev node too, as we've
been doing in kernel 3.19 and older.

This has been tested on a Dell Latitude D620 and a Dell Latitude E6400,
which both have a V2 touchpad + a DualPoint Stick which reports bare packets.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Bare packets should be reported via the same evdev device independent on
whether they are detected on the beginning of a packet or in the middle
of a packet.

This has been tested on a Dell Latitude E6400, where the DualPoint Stick
reports bare packets, which get reported via dev3 when the touchpad is
idle, and via dev2 when the touchpad and stick are used simultaneously.

This commit fixes this inconsistency by always reporting bare packets via
dev3. Note that since the come from a DualPoint Stick they really should be
reported via dev2, this gets fixed in a later commit.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Pull USB fixes from Greg KH:
 "Here are some small USB fixes and new device ids for 4.0-rc6.  Nothing
  major, some xhci fixes for reported problems, and some usb-serial
  device ids.

  All have been in linux-next for a while"

* tag 'usb-4.0-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  USB: ftdi_sio: Use jtag quirk for SNAP Connect E10
  usb: isp1760: fix spin unlock in the error path of isp1760_udc_start
  usb: xhci: apply XHCI_AVOID_BEI quirk to all Intel xHCI controllers
  usb: xhci: handle Config Error Change (CEC) in xhci driver
  USB: keyspan_pda: add new device id
  USB: ftdi_sio: Added custom PID for Synapse Wireless product

Pull staging driver fixes from Greg KH:
 "Here are some staging driver fixes, well, really all just IIO driver
  fixes, for 4.0-rc6.  They fix issues that have been reported with
  these drivers.

  All of these patches have been in linux-next for a while"

* tag 'staging-4.0-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  iio: imu: Use iio_trigger_get for indio_dev->trig assignment
  iio: adc: vf610: use ADC clock within specification
  iio/adc/cc10001_adc.c: Fix !HAS_IOMEM build
  iio: core: Fix double free.
  iio:inv-mpu6050: Fix inconsistency for the scale channel
  staging: iio: dummy: Fix undefined symbol build error
  iio: inv_mpu6050: Clear timestamps fifo while resetting hardware fifo
  staging: iio: hmc5843: Set iio name property in sysfs
  iio: bmc150: change sampling frequency
  iio: fix drivers that check buffer->scan_mask

Pull tty/serial fixes from Greg KH:
 "Here are 3 serial driver fixes for 4.0-rc6.  They fix some reported
  issues with the samsung and fsl_lpuart drivers.

  All have been in linux-next for a while"

* tag 'tty-4.0-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  tty: serial: fsl_lpuart: clear receive flag on FIFO flush
  tty: serial: fsl_lpuart: specify transmit FIFO size
  serial: samsung: Clear operation mode on UART shutdown

Pull input subsystem fixes from Dmitry Torokhov:
 "A fix for ALPS driver for issue introduced in the latest update and a
  tweak for yet another Lenovo box in Synaptics.

  There will be more ALPS tweaks coming.."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: define INPUT_PROP_ACCELEROMETER behavior
  Input: synaptics - fix min-max quirk value for E440
  Input: synaptics - add quirk for Thinkpad E440
  Input: ALPS - fix max coordinates for v5 and v7 protocols
  Input: add MT_TOOL_PALM

Pull block layer fix from Jens Axboe:
 "Just one patch in this pull request, fixing a regression caused by a
  'mathematically correct' change to lcm()"

* 'for-linus' of git://git.kernel.dk/linux-block:
  block: fix blk_stack_limits() regression due to lcm() change

Pull x86 fixes from Ingo Molnar:
 "Misc fixes: a SYSRET single-stepping fix, a dmi-scan robustization
  fix, a reboot quirk and a kgdb fixlet"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  kgdb/x86: Fix reporting of 'si' in kgdb on x86_64
  x86/asm/entry/64: Disable opportunistic SYSRET if regs->flags has TF set
  x86/reboot: Add ASRock Q1900DC-ITX mainboard reboot quirk
  MAINTAINERS: Change the x86 microcode loader maintainer
  firmware: dmi_scan: Prevent dmi_num integer overflow

Pull perf fixes from Ingo Molnar:
 "Two x86 Intel PMU constraint handling fixes"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/intel: Fix Haswell CYCLE_ACTIVITY.* counter constraints
  perf/x86/intel: Filter branches for PEBS event

Pull devicetree fix from Grant Likely:
 "Simple bugfix for bad device tree data on the PA-Semi platform"

* tag 'devicetree-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/glikely/linux:
  drivers/of: Add empty ranges quirk for PA-Semi

Pull CIFS fixes from Steve French:
 "A set of small cifs fixes fixing a memory leak, kernel oops, and
  infinite loop (and some spotted by Coverity)"

* 'for-next' of git://git.samba.org/sfrench/cifs-2.6:
  Fix warning
  Fix another dereference before null check warning
  CIFS: session servername can't be null
  Fix warning on impossible comparison
  Fix coverity warning
  Fix dereference before null check warning
  Don't ignore errors on encrypting password in SMBTcon
  Fix warning on uninitialized buftype
  cifs: potential memory leaks when parsing mnt opts
  cifs: fix use-after-free bug in find_writable_file
  cifs: smb2_clone_range() - exit on unhandled error