linux.git/drivers/md/raid10.c, branch v4.8-rc2

block: rename bio bi_rw to bi_opf

2016-08-07T20:41:02+00:00

Since commit 63a4cc24867d, bio->bi_rw contains flags in the lower
portion and the op code in the higher portions. This means that
old code that relies on manually setting bi_rw is most likely
going to be broken. Instead of letting that brokeness linger,
rename the member, to force old and out-of-tree code to break
at compile time instead of at runtime.

No intended functional changes in this commit.

Signed-off-by: Jens Axboe

Merge branch 'mymd/for-next' into mymd/for-linus

2016-07-28T16:34:14+00:00

raid10: improve random reads performance

2016-07-19T22:20:28+00:00

RAID10 random read performance is lower than expected due to excessive spinlock
utilisation which is required mostly for rebuild/resync. Simplify allow_barrier
as it's in IO path and encounters a lot of unnecessary congestion.

As lower_barrier just takes a lock in order to decrement a counter, convert
counter (nr_pending) into atomic variable and remove the spin lock. There is
also a congestion for wake_up (it uses lock internally) so call it only when
it's really needed. As wake_up is not called constantly anymore, ensure process
waiting to raise a barrier is notified when there are no more waiting IOs.

Signed-off-by: Tomasz Majchrzak 
Signed-off-by: Shaohua Li

md: use seconds granularity for error logging

2016-07-19T18:00:47+00:00

The md code stores the exact time of the last error in the
last_read_error variable using a timespec structure. It only
ever uses the seconds portion of that though, so we can
use a scalar for it.

There won't be an overflow in 2038 here, because it already
used monotonic time and 32-bit is enough for that, but I've
decided to use time64_t for consistency in the conversion.

Signed-off-by: Arnd Bergmann 
Signed-off-by: Shaohua Li

md: reduce the number of synchronize_rcu() calls when multiple devices fail.

2016-06-13T18:54:22+00:00

Every time a device is removed with ->hot_remove_disk() a synchronize_rcu() call is made
which can delay several milliseconds in some case.
If lots of devices fail at once - as could happen with a large RAID10 where one set
of devices are removed all at once - these delays can add up to be very inconcenient.

As failure is not reversible we can check for that first, setting a
separate flag if it is found, and then all synchronize_rcu() once for
all the flagged devices.  Then ->hot_remove_disk() function can skip the
synchronize_rcu() step if the flag is set.

fix build error(Shaohua)
Signed-off-by: NeilBrown 
Signed-off-by: Shaohua Li

md: be extra careful not to take a reference to a Faulty device.

2016-06-13T18:54:21+00:00

It is important that we never increment rdev->nr_pending on a Faulty
device as ->hot_remove_disk() assumes that once the Faulty flag is visible
no code will take a new reference.

Some places take a new reference after only check In_sync.  This should
be safe as the two are changed together.  However to make the code more
obviously safe, add checks for 'Faulty' as well.

Note: the actual rule is:
  Never increment nr_pending if  Faulty is set and Blocked is clear,
  never clear Faulty, and never set Blocked without holding a reference
  through nr_pending.

fix build error (Shaohua)
Signed-off-by: NeilBrown 
Signed-off-by: Shaohua Li

md/raid10: simplify print_conf a little.

2016-06-13T18:54:16+00:00

'tmp' is only ever used to extract 'tmp->rdev', so just use 'rdev' directly.

Signed-off-by: NeilBrown 
Signed-off-by: Shaohua Li

md/raid10: minor code improvement in fix_read_error()

2016-06-13T18:54:16+00:00

rdev already holds conf->mirrors[d].rdev, so no need to load it again.

Signed-off-by: NeilBrown 
Signed-off-by: Shaohua Li

md/raid10: add rcu protection to rdev access during reshape.

2016-06-13T18:54:15+00:00

mirrors[].rdev can become NULL at any point unless:
   - a counted reference is held
   - ->reconfig_mutex is held, or
   - rcu_read_lock() is held

Reshape isn't always suitably careful as in the past rdev couldn't be
removed during reshape.  It can now, so add protection.

Signed-off-by: NeilBrown 
Signed-off-by: Shaohua Li

md/raid10: add rcu protection to rdev access in raid10_sync_request.

2016-06-13T18:54:14+00:00

mirrors[].rdev can become NULL at any point unless:
  - a counted reference is held
  - ->reconfig_mutex is held, or
  - rcu_read_lock() is held

Previously they could not become NULL during a resync/recovery/reshape either.
However when remove_and_add_spares() was added to hot_remove_disk(), that
changed.

So raid10_sync_request didn't previously need to protect rdev access,
but now it does.

Fix missed check(Shaohua)
Signed-off-by: NeilBrown 
Signed-off-by: Shaohua Li