Skip to content

L
linux-davinci
Switch branch/tag
  1. 20 Apr, 2009 1 commit
  3. 17 Apr, 2009 1 commit
    • NeilBrown's avatar
      md: update sync_completed and reshape_position even more often. · c03f6a19
      NeilBrown authored 
      There are circumstances when a user-space process might need to
"oversee" a resync/reshape process.  For example when doing an
in-place reshape of a raid5, it is prudent to take a backup of each
section before reshaping it as this is the only way to provide
safety against an unplanned shutdown (i.e. crash/power failure).

The sync_max sysfs value can be used to stop the resync from
advancing beyond a particular point.
So user-space can:
  suspend IO to the first section and back it up
  set 'sync_max' to the end of the section
  wait for 'sync_completed' to reach that point
  resume IO on the first section and move on to the next section.

However this process requires the kernel and user-space to run in
lock-step which could introduce unnecessary delays.

It would be better if a 'double buffered' approach could be used with
userspace and kernel space working on different sections with the
'next' section always ready when the 'current' section is finished.

One problem with implementing this is that sync_completed is only
guaranteed to be updated when the sync process reaches sync_max.
(it is updated on a time basis at other times, but it is hard to rely
on that).  This defeats some of the double buffering.

With this patch, sync_completed (and reshape_position) get updated as
the current position approaches sync_max, so there is room for
userspace to advance sync_max early without losing updates.

To be precise, sync_completed is updated when the current sync
position reaches half way between the current value of sync_completed
and the value of sync_max.  This will usually be a good time for user
space to update sync_max.

If sync_max does not get updated, the updates to sync_completed
(together with associated metadata updates) will occur at an
exponentially increasing frequency which will get unreasonably fast
(one update every page) immediately before the process hits sync_max
and stops.  So the update rate will be unreasonably fast only for an
insignificant period of time.
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
      c03f6a19
  5. 14 Apr, 2009 3 commits
    • NeilBrown's avatar
      md: improve usefulness and accuracy of sysfs file md/sync_completed. · acb180b0
      NeilBrown authored 
      The sync_completed file reports how much of a resync (or recovery or
reshape) has been completed.
However due to the possibility of out-of-order completion of writes,
it is not certain to be accurate.

We have an internal value - mddev->curr_resync_completed - which is an
accurate value (though it might not always be quite so uptodate).

So:
 - make curr_resync_completed be uptodate a little more often,
   particularly when raid5 reshape updates status in the metadata
 - report curr_resync_completed in the sysfs file
 - allow poll/select to report all updates to md/sync_completed.

This makes sync_completed completed usable by any external metadata
handler that wants to record this status information in its metadata.
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
      acb180b0
    • NeilBrown's avatar
      md: allow setting newly added device to 'in_sync' via sysfs. · 6d56e278
      NeilBrown authored 
      When adding devices to an active array via sysfs, there is currently
no way to mark a device as 'in-sync' which is useful when
incrementally assembling an array.

So add that option.
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
      6d56e278
    • Christoph Hellwig's avatar
      md: tiny md.h cleanups · 63fe0817
      Christoph Hellwig authored 
      - update inclusion guard and make sure it covers the whole file
 - remove superflous #ifdef CONFIG_BLOCK
 - make sure all required headers are included so that new users aren't
   required to include others before
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
      63fe0817
  7. 11 Apr, 2009 2 commits
    • Linus Torvalds's avatar
      Revert "ACPI battery: fix async boot oops" · b0cbc861
      Linus Torvalds authored 
      This reverts commit 5d38258e, since the
underlying problem got fixed properly in the previous commit ("async:
Fix module loading async-work regression").

Cc: Arkadiusz Miskiewicz <a.miskiewicz@gmail.com>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Len Brown <len.brown@intel.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b0cbc861
    • Linus Torvalds's avatar
      async: Fix module loading async-work regression · d6de2c80
      Linus Torvalds authored 
      Several drivers use asynchronous work to do device discovery, and we
synchronize with them in the compiled-in case before we actually try to
mount root filesystems etc.

However, when compiled as modules, that synchronization is missing - the
module loading completes, but the driver hasn't actually finished
probing for devices, and that means that any user mode that expects to
use the devices after the 'insmod' is now potentially broken.

We already saw one case of a similar issue in the ACPI battery code,
where the kernel itself expected the module to be all done, and unmapped
the init memory - but the async device discovery was still running.
That got hacked around by just removing the "__init" (see commit
5d38258e "ACPI battery: fix async boot
oops"), but the real fix is to just make the module loading wait for all
async work to be completed.

It will slow down module loading, but since common devices should be
built in anyway, and since the bug is really annoying and hard to handle
from user space (and caused several S3 resume regressions), the simple
fix to wait is the right one.

This fixes at least

	http://bugzilla.kernel.org/show_bug.cgi?id=13063

but probably a few other bugzilla entries too (12936, for example), and
is confirmed to fix Rafael's storage driver breakage after resume bug
report (no bugzilla entry).

We should also be able to now revert that ACPI battery fix.
Reported-and-tested-by: default avatarRafael J. Wysocki <rjw@suse.com>
Tested-by: default avatarHeinz Diehl <htd@fancy-poultry.org>
Acked-by: default avatarArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d6de2c80
  9. 10 Apr, 2009 8 commits
  11. 09 Apr, 2009 25 commits