This code looks racy.

The only possible race is if two modules try to register at the same
time and that won't happen.  But make the code look safe anyway.
Signed-off-by: NeilBrown <neilb@suse.com>

In gather_all_resync_info, we need to read the disk bitmap sb and
check if it needs recovery.
Reviewed-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

Introduce MD_CLUSTER_BEGIN_JOIN_CLUSTER flag to make sure
complete(&cinfo->completion) is only be invoked when node
join cluster. Otherwise node failure could also call the
complete, and it doesn't make sense to do it.
Reviewed-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

We also need to free the lock resource before goto out.
Reviewed-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

The sb_lock is not used anywhere, so let's remove it.
Reviewed-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

If the node just join the cluster, and receive the msg from other nodes
before init suspend_list, it will cause kernel crash due to NULL pointer
dereference, so move the initializations early to fix the bug.

md-cluster: Joined cluster 3578507b-e0cb-6d4f-6322-696cd7b1b10c slot 3
BUG: unable to handle kernel NULL pointer dereference at           (null)
... ... ...
Call Trace:
[<ffffffffa0444924>] process_recvd_msg+0x2e4/0x330 [md_cluster]
[<ffffffffa0444a06>] recv_daemon+0x96/0x170 [md_cluster]
[<ffffffffa045189d>] md_thread+0x11d/0x170 [md_mod]
[<ffffffff810768c4>] kthread+0xb4/0xc0
[<ffffffff8151927c>] ret_from_fork+0x7c/0xb0
... ... ...
RIP  [<ffffffffa0443581>] __remove_suspend_info+0x11/0xa0 [md_cluster]
Reviewed-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

In complicated cluster environment, it is possible that the
dlm lock couldn't be get/convert on purpose, the related err
info is added for better debug potential issue.

For lockres_free, if the lock is blocking by a lock request or
conversion request, then dlm_unlock just put it back to grant
queue, so need to ensure the lock is free finally.
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

We should init completion within lockres_init, otherwise
completion could be initialized more than one time during
it's life cycle.
Reviewed-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

There is problem with previous communication mechanism, and we got below
deadlock scenario with cluster which has 3 nodes.

	Sender                	    Receiver        		Receiver

	token(EX)
       message(EX)
      writes message
   downconverts message(CR)
      requests ack(EX)
		                  get message(CR)            gets message(CR)
                		  reads message                reads message
		               requests EX on message    requests EX on message

To fix this problem, we do the following changes:

1. the sender downconverts MESSAGE to CW rather than CR.
2. and the receiver request PR lock not EX lock on message.

And in case we failed to down-convert EX to CW on message, it is better to
unlock message otherthan still hold the lock.
Reviewed-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Lidong Zhong <ldzhong@suse.com>
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

When node A stops an array while the array is doing a resync, we need
to let another node B take over the resync task.

To achieve the goal, we need the A send an explicit BITMAP_NEEDS_SYNC
message to the cluster. And the node B which received that message will
invoke __recover_slot to do resync.
Reviewed-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

Make recover_slot as a wraper to __recover_slot, since the
logic of __recover_slot can be reused for the condition
when other nodes need to take over the resync job.
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

Reviewed-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

We used to set up the safemode_timer timer in md_run. If md_run
would fail before the timer was set up we'd end up trying to modify
a timer that doesn't have a callback function when we access safe_delay_store,
which would trigger a BUG.

neilb: delete init_timer() call as setup_timer() does that.
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: NeilBrown <neilb@suse.com>

It is possible (though unlikely) for a reshape to be
interrupted between the time that end_reshape is called
and the time when raid5_finish_reshape is called.

This can leave conf->reshape_progress set to MaxSector,
but mddev->reshape_position not.

This combination confused reshape_request() when ->reshape_backwards.
As conf->reshape_progress is so high, it seems the reshape hasn't
really begun.  But assuming MaxSector is a valid address only
leads to sorrow.

So ensure reshape_position and reshape_progress both agree,
and add an extra check in reshape_request() just in case they don't.
Signed-off-by: NeilBrown <neilb@suse.com>

There can be a small window between the moment that recovery
actually writes the last block and the time when various sysfs
and /proc/mdstat attributes report that it has finished.
During this time, 'sync_completed' can have the wrong value.
This can confuse monitoring software.

So:
 - don't set curr_resync_completed beyond the end of the devices,
 - set it correctly when resync/recovery has completed.
Signed-off-by: NeilBrown <neilb@suse.com>

While it generally shouldn't happen, it is not impossible for
curr_resync_completed to exceed resync_max.
This can particularly happen when reshaping RAID5 - the current
status isn't copied to curr_resync_completed promptly, so when it
is, it can exceed resync_max.
This happens when the reshape is 'frozen', resync_max is set low,
and reshape is re-enabled.

Taking a difference between two unsigned numbers is always dangerous
anyway, so add a test to behave correctly if
   curr_resync_completed > resync_max
Signed-off-by: NeilBrown <neilb@suse.com>

This ensures that 'sync_action' will show 'recover' immediately the
array is started.  If there is no spare the status will change to
'idle' once that is detected.

Clear MD_RECOVERY_RECOVER for a read-only array to ensure this change
happens.

This allows scripts which monitor status not to get confused -
particularly my test scripts.
Signed-off-by: NeilBrown <neilb@suse.com>

This code is calculating:
  writepos, which is the furthest along address (device-space) that we
     *will* be writing to
  readpos, which is the earliest address that we *could* possible read
     from, and
  safepos, which is the earliest address in the 'old' section that we
     might read from after a crash when the reshape position is
     recovered from metadata.

  The first is a precise calculation, so clipping at zero doesn't
  make sense.  As the reshape position is now guaranteed to always be
  a multiple of reshape_sectors and as we already BUG_ON when
  reshape_progress is zero, there is no point in this min_t() call.

  The readpos and safepos are worst case - actual value depends on
  precise geometry.  That worst case could be negative, which is only
  a problem because we are storing the value in an unsigned.
  So leave the min_t() for those.
Signed-off-by: NeilBrown <neilb@suse.com>

When reshaping, we work in units of the largest chunk size.
If changing from a larger to a smaller chunk size, that means we
reshape more than one stripe at a time.  So the required alignment
of reshape_position needs to take into account both the old
and new chunk size.

This means that both 'here_new' and 'here_old' are calculated with
respect to the same (maximum) chunk size, so testing if they are the
same when delta_disks is zero becomes pointless.
Signed-off-by: NeilBrown <neilb@suse.com>

The chunk_sectors and new_chunk_sectors fields of mddev can be changed
any time (via sysfs) that the reconfig mutex can be taken.  So raid5
keeps internal copies in 'conf' which are stable except for a short
locked moment when reshape stops/starts.

So any access that does not hold reconfig_mutex should use the 'conf'
values, not the 'mddev' values.
Several don't.

This could result in corruption if new values were written at awkward
times.

Also use min() or max() rather than open-coding.
Signed-off-by: NeilBrown <neilb@suse.com>

These aren't really needed when no reshape is happening,
but it is safer to have them always set to a meaningful value.
The next patch will use ->prev_chunk_sectors without checking
if a reshape is happening (because that makes the code simpler),
and this patch makes that safe.
Signed-off-by: NeilBrown <neilb@suse.com>

Signed-off-by: NeilBrown <neilb@suse.com>

md/raid5 only updates ->reshape_position (which is stored in
metadata and is authoritative) occasionally, but particularly
when getting closed to ->resync_max as it must be correct
when ->resync_max is reached.

When mdadm tries to stop an array which is reshaping it will:
 - freeze the reshape,
 - set resync_max to where the reshape has reached.
 - unfreeze the reshape.
When this happens, the reshape is aborted and then restarted.

The restart doesn't check that resync_max is close, and so doesn't
update ->reshape_position like it should.
This results in the reshape stopping, but ->reshape_position being
incorrect.

So on that first call to reshape_request, make sure ->reshape_position
is updated if needed.
Signed-off-by: NeilBrown <neilb@suse.com>

When checking sync_action in a script, we want to be sure it is
as accurate as possible.
As resync/reshape etc doesn't always start immediately (a separate
thread is scheduled to do it), it is best if 'action_show'
checks if MD_RECOVER_NEEDED is set (which it does) and in that
case reports what is likely to start soon (which it only sometimes
does).

So:
 - report 'reshape' if reshape_position suggests one might start.
 - set MD_RECOVERY_RECOVER in raid1_reshape(), because that is very
   likely to happen next.
Signed-off-by: NeilBrown <neilb@suse.com>

Currently when a recovery completes, mdstat shows that it has finished
before the new device is marked as a full member.  Because of this it
can appear to a script that the recovery finished but the array isn't
in sync.

So while MD_RECOVERY_DONE is still set, keep mdstat reporting "recovery".
Once md_reap_sync_thread() completes, the spare will be active and then
MD_RECOVERY_DONE will be cleared.

To ensure this is race-free, set MD_RECOVERY_DONE before clearning
curr_resync.
Signed-off-by: NeilBrown <neilb@suse.com>

This implements XOR syndrome calculation using NEON intrinsics.
As before, the module can be built for ARM and arm64 from the
same source.

Relative performance on a Cortex-A57 based system:

  raid6: int64x1  gen()   905 MB/s
  raid6: int64x1  xor()   881 MB/s
  raid6: int64x2  gen()  1343 MB/s
  raid6: int64x2  xor()  1286 MB/s
  raid6: int64x4  gen()  1896 MB/s
  raid6: int64x4  xor()  1321 MB/s
  raid6: int64x8  gen()  1773 MB/s
  raid6: int64x8  xor()  1165 MB/s
  raid6: neonx1   gen()  1834 MB/s
  raid6: neonx1   xor()  1278 MB/s
  raid6: neonx2   gen()  2528 MB/s
  raid6: neonx2   xor()  1942 MB/s
  raid6: neonx4   gen()  2888 MB/s
  raid6: neonx4   xor()  2334 MB/s
  raid6: neonx8   gen()  2957 MB/s
  raid6: neonx8   xor()  2232 MB/s
  raid6: using algorithm neonx8 gen() 2957 MB/s
  raid6: .... xor() 2232 MB/s, rmw enabled

Cc: Markus Stockhausen <stockhausen@collogia.de>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NeilBrown <neilb@suse.com>

When a (e.g.) RAID5 array is reshaped to RAID0, the updating
of queue parameters (e.g. max number of sectors per bio) is
done in the wrong place.
It should be part of ->run, but it is actually part of ->takeover.
This means it happens before level_store() calls:

	blk_set_stacking_limits(&mddev->queue->limits);

and so it ineffective.  This can lead to errors from underlying
devices.

So move all the relevant settings out of create_stripe_zones()
and into raid0_run().

As this can lead to a bug-on it is suitable for any -stable
kernel which supports reshape to RAID0.  So 2.6.35 or later.
As the bug has been present for five years there is no urgency,
so no need to rush into -stable.

Fixes: 9af204cf ("md: Add support for Raid5->Raid0 and Raid10->Raid0 takeover")
Cc: stable@vger.kernel.org (v2.6.35+ - please delay until after -final release).
Reported-by: Yi Zhang <yizhan@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.com>

There is no point assigning '\0' to file->pathname[0] as
file is now zeroed out, so remove that branch and
simplify the code.

[Original patch combined this with the change to use
 kzalloc.  I split the two so that the change to kzalloc
 is easier to backport. - neilb]
Signed-off-by: Benjamin Randazzo <benjamin@randazzo.fr>
Signed-off-by: NeilBrown <neilb@suse.com>

I have a report of drop_one_stripe() called from
raid5_cache_scan() apparently finding ->max_nr_stripes == 0.

This should not be allowed.

So add a test to keep max_nr_stripes above min_nr_stripes.

Also use a 'mask' rather than a 'mod' in drop_one_stripe
to ensure 'hash' is valid even if max_nr_stripes does reach zero.


Fixes: edbe83ab ("md/raid5: allow the stripe_cache to grow and shrink.")
Cc: stable@vger.kernel.org (4.1 - please release with 2d5b569b)
Reported-by: Tomas Papan <tomas.papan@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.com>

In drivers/md/md.c get_bitmap_file() uses kmalloc() for creating a
mdu_bitmap_file_t called "file".

5769         file = kmalloc(sizeof(*file), GFP_NOIO);
5770         if (!file)
5771                 return -ENOMEM;

This structure is copied to user space at the end of the function.

5786         if (err == 0 &&
5787             copy_to_user(arg, file, sizeof(*file)))
5788                 err = -EFAULT

But if bitmap is disabled only the first byte of "file" is initialized
with zero, so it's possible to read some bytes (up to 4095) of kernel
space memory from user space. This is an information leak.

5775         /* bitmap disabled, zero the first byte and copy out */
5776         if (!mddev->bitmap_info.file)
5777                 file->pathname[0] = '\0';
Signed-off-by: Benjamin Randazzo <benjamin@randazzo.fr>
Signed-off-by: NeilBrown <neilb@suse.com>

raid1_end_read_request() assumes that the In_sync bits are consistent
with the ->degaded count.
raid1_spare_active updates the In_sync bit before the ->degraded count
and so exposes an inconsistency, as does error()
So extend the spinlock in raid1_spare_active() and error() to hide those
inconsistencies.

This should probably be part of
  Commit: 34cab6f4 ("md/raid1: fix test for 'was read error from
  last working device'.")
as it addresses the same issue.  It fixes the same bug and should go
to -stable for same reasons.

Fixes: 76073054 ("md/raid1: clean up read_balance.")
Cc: stable@vger.kernel.org (v3.0+)
Signed-off-by: NeilBrown <neilb@suse.com>

Pull powerpc fixes from Michael Ellerman:
 - TCE table memory calculation fix from Alexey
 - Build fix for ans-lcd from Luis
 - Unbalanced IRQ warning fix from Alistair

* tag 'powerpc-4.2-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/eeh-powernv: Fix unbalanced IRQ warning
  macintosh/ans-lcd: fix build failure after module_init/exit relocation
  powerpc/powernv/ioda2: Fix calculation for memory allocated for TCE table

Ted Ts'o reports that his Lenovo T540p ThinkPad crashes at boot if
attached to the docking station.  This is a regression that he was able
to bisect to commit 8c7b5ccb: "drm/i915: Use atomic helpers for
computing changed flags:"

The reason seems to be the new call to drm_atomic_helper_check_modeset()
added to intel_modeset_compute_config(), which in turn calls
update_connector_routing(), and somehow ends up picking a NULL crtc for
the connector state, causing the subsequent drm_crtc_index() to OOPS.

Daniel Vetter says that the fundamental issue seems to be confusion in
the encoder selection, and this isn't the right fix, but while he chases
down the proper fix, this at least avoids the NULL pointer dereference
and makes Ted's docking station work again.
Reported-bisected-and-tested-by: Theodore Ts'o <tytso@mit.edu>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Mani Nikula <jani.nikula@linux.intel.com>
Cc: Dave Airlie <airlied@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull SCSI fixes from James Bottomley:
 "A set of three fixes for the ipr driver and one fairly major one for
  memory leaks in the mq path of SCSI"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: fix memory leak with scsi-mq
  ipr: Fix invalid array indexing for HRRQ
  ipr: Fix incorrect trace indexing
  ipr: Fix locking for unit attention handling

Pull ARM SoC fixes from Olof Johansson:
 "Things are calming down nicely here w.r.t. fixes.  This batch
  includes two week's worth since I missed to send before -rc4.

  Nothing particularly scary to point out, smaller fixes here and there.
  Shortlog describes it pretty well"

* tag 'armsoc-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  ARM: dts: keystone: fix dt bindings to use post div register for mainpll
  ARM: nomadik: disable UART0 on Nomadik boards
  ARM: dts: i.MX35: Fix can support.
  ARM: OMAP2+: hwmod: Fix _wait_target_ready() for hwmods without sysc
  ARM: dts: add CPU OPP and regulator supply property for exynos4210
  ARM: dts: Update video-phy node with syscon phandle for exynos3250
  ARM: DRA7: hwmod: fix gpmc hwmod

Pull VFS fix from Al Viro:
 "Spurious ENOTDIR fix"

This should fix the problems reported by Dominique Martinet and Hugh
Dickins.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  link_path_walk(): be careful when failing with ENOTDIR

In RCU mode we might end up with dentry evicted just we check
that it's a directory.  In such case we should return ECHILD
rather than ENOTDIR, so that pathwalk would be retries in non-RCU
mode.

Breakage had been introduced in commit b18825a7 - prior to that
we were looking at nd->inode, which had been fetched before
verifying that ->d_seq was still valid.  That form of check
would only be satisfied if at some point the pathname prefix
would indeed have resolved to a non-directory.  The fix consists
of checking ->d_seq after we'd run into a non-directory dentry,
and failing with ECHILD in case of mismatch.

Note that all branches since 3.12 have that problem...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Pull dmaengine fixes from Vinod Koul:
 "We had a regression due to reuse of descriptor so we have reverted
  that.

  The rest are driver fixes:

   - at_hdmac and at_xdmac for residue, trannfer width, and channel config
   - pl330 final fix for dma fails and overflow issue
   - xgene resouce map fix
   - mv_xor big endian op fix"

* tag 'dmaengine-fix-4.2-rc5' of git://git.infradead.org/users/vkoul/slave-dma:
  Revert "dmaengine: virt-dma: don't always free descriptor upon completion"
  dmaengine: mv_xor: fix big endian operation in register mode
  dmaengine: xgene-dma: Fix the resource map to handle overlapping
  dmaengine: at_xdmac: fix transfer data width in at_xdmac_prep_slave_sg()
  dmaengine: at_hdmac: fix residue computation
  dmaengine: at_xdmac: fix bug about channel configuration
  dmaengine: pl330: Really fix choppy sound because of wrong residue calculation
  dmaengine: pl330: Fix overflow when reporting residue in memcpy

Pull irq fixlets from Thomas Gleixner:
 "Just two updates to the maintainers file"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  MAINTAINERS: Appoint Jiang and Marc as irqdomain maintainers
  MAINTAINERS: Appoint Marc Zyngier as irqchips co-maintainer