linux.git/drivers/md/md.h, branch v4.0

md: wakeup thread upon rdev_dec_pending()

2015-02-05T22:32:57+00:00

After each call to rdev_dec_pending() we should wakeup the
md thread if the device is found to be faulty.
Otherwise we'll incur heavy delays on failing devices.

Signed-off-by: Neil Brown 
Signed-off-by: Hannes Reinecke

md: move mddev_lock and related to md.h

2015-02-05T22:32:56+00:00

The one which is not inline (mddev_unlock) gets EXPORTed.

This makes the locking available to personality modules so that it
doesn't have to be imposed upon them.

Signed-off-by: NeilBrown

md: use mddev->lock to protect updates to resync_{min,max}.

2015-02-05T22:32:56+00:00

There are interdependencies between these two sysfs attributes
and whether a resync is currently running.

Rather than depending on reconfig_mutex to ensure no races when
testing these interdependencies are met, use the spinlock.
This will allow the mutex to be remove from protecting this
code in a subsequent patch.

Signed-off-by: NeilBrown

md: move GET_BITMAP_FILE ioctl out from mddev_lock.

2015-02-05T22:32:56+00:00

It makes more sense to report bitmap_info->file, rather than
bitmap->file (the later is only available once the array is
active).

With that change, use mddev->lock to protect bitmap_info being
set to NULL, and we can call get_bitmap_file() without taking
the mutex.

Signed-off-by: NeilBrown

md/bitmap: protect clearing of ->bitmap by mddev->lock

2015-02-05T22:32:55+00:00

This makes it safe to inspect the struct while holding only
the spinlock.

Signed-off-by: NeilBrown

md: protect ->pers changes with mddev->lock

2015-02-03T21:35:53+00:00

->pers is already protected by ->reconfig_mutex, and
cannot possibly change when there are threads running or
outstanding IO.

However there are some places where we access ->pers
not in a thread or IO context, and where ->reconfig_mutex
is unnecessarily heavy-weight:  level_show and md_seq_show().

So protect all changes, and those accesses, with ->lock.
This is a step toward taking those accesses out from under
reconfig_mutex.

[Fixed missing "mddev->pers" -> "pers" conversion, thanks to
 Dan Carpenter ]

Signed-off-by: NeilBrown

md: rename ->stop to ->free

2015-02-03T21:35:52+00:00

Now that the ->stop function only frees the private data,
rename is accordingly.

Also pass in the private pointer as an arg rather than using
mddev->private.  This flexibility will be useful in level_store().

Finally, don't clear ->private.  It doesn't make sense to clear
it seeing that isn't what we free, and it is no longer necessary
to clear ->private (it was some time ago before  ->to_remove was
introduced).

Setting ->to_remove in ->free() is a bit of a wart, but not a
big problem at the moment.

Signed-off-by: NeilBrown

md: make merge_bvec_fn more robust in face of personality changes.

2015-02-03T21:35:52+00:00

There is no locking around calls to merge_bvec_fn(), so
it is possible that calls which coincide with a level (or personality)
change could go wrong.

So create a central dispatch point for these functions and use
rcu_read_lock().
If the array is suspended, reject any merge that can be rejected.
If not, we know it is safe to call the function.

Signed-off-by: NeilBrown

md: make ->congested robust against personality changes.

2015-02-03T21:35:52+00:00

There is currently no locking around calls to the 'congested'
bdi function.  If called at an awkward time while an array is
being converted from one level (or personality) to another, there
is a tiny chance of running code in an unreferenced module etc.

So add a 'congested' function to the md_personality operations
structure, and call it with appropriate locking from a central
'mddev_congested'.

When the array personality is changing the array will be 'suspended'
so no IO is processed.
If mddev_congested detects this, it simply reports that the
array is congested, which is a safe guess.
As mddev_suspend calls synchronize_rcu(), mddev_congested can
avoid races by included the whole call inside an rcu_read_lock()
region.
This require that the congested functions for all subordinate devices
can be run under rcu_lock.  Fortunately this is the case.

Signed-off-by: NeilBrown

md: rename mddev->write_lock to mddev->lock

2015-02-03T21:35:52+00:00

This lock is used for (slightly) more than helping with writing
superblocks, and it will soon be extended further.  So the
name is inappropriate.

Also, the _irq variant hasn't been needed since 2.6.37 as it is
never taking from interrupt or bh context.

So:
  -rename write_lock to lock
  -document what it protects
  -remove _irq ... except in md_flush_request() as there
     is no wait_event_lock() (with no _irq).  This can be
     cleaned up after appropriate changes to wait.h.

Signed-off-by: NeilBrown