1. 08 12月, 2011 2 次提交
    • N
      md: take a reference to mddev during sysfs access. · af8a2434
      NeilBrown 提交于
      
      When we are accessing an mddev via sysfs we know that the
      mddev cannot disappear because it has an embedded kobj which
      is refcounted by sysfs.
      And we also take the mddev_lock.
      However this is not enough.
      
      The final mddev_put could have been called and the
      mddev_delayed_delete is waiting for sysfs to let go so it can destroy
      the kobj and mddev.
      In this state there are a lot of changes that should not be attempted.
      
      To to guard against this we:
       - initialise mddev->all_mddevs in on last put so the state can be
         easily detected.
       - in md_attr_show and md_attr_store, check ->all_mddevs under
         all_mddevs_lock and mddev_get the mddev if it still appears to
         be active.
      
      This means that if we get to sysfs as the mddev is being deleted we
      will get -EBUSY.
      
      rdev_attr_store and rdev_attr_show are similar but already have
      sufficient protection.  They check that rdev->mddev still points to
      mddev after taking mddev_lock.  As this is cleared  before delayed
      removal which can only be requested under the mddev_lock, this
      ensure the rdev and mddev are still alive.
      Signed-off-by: NNeilBrown <neilb@suse.de>
      af8a2434
    • N
      md: refine interpretation of "hold_active == UNTIL_IOCTL". · 1d23f178
      NeilBrown 提交于
      We like md devices to disappear when they really are not needed.
      However it is not possible to tell from the current state whether it
      is needed or not.  We can only tell from recent history of changes.
      
      In particular immediately after we create an md device it looks very
      similar to immediately after we have finished with it.
      
      So we always preserve a newly created md device until something
      significant happens.  This state is stored in 'hold_active'.
      
      The normal case is to keep it until an ioctl happens, as that will
      normally either activate it, or explicitly de-activate it.  If it
      doesn't then it was probably created by mistake and it is now time to
      get rid of it.
      
      We can also modify an array via sysfs (instead of via ioctl) and we
      currently treat any change via sysfs like an ioctl as a sign that if
      it now isn't more active, it should be destroyed.
      However this is not appropriate as changes made via sysfs are more
      gradual so we should look for a more definitive change.
      
      So this patch only clears 'hold_active' from UNTIL_IOCTL to clear when
      the array_state is changed via sysfs.  Other changes via sysfs
      are ignored.
      Signed-off-by: NNeilBrown <neilb@suse.de>
      1d23f178
  2. 23 11月, 2011 1 次提交
    • N
      md/lock: ensure updates to page_attrs are properly locked. · 7c8f4247
      NeilBrown 提交于
      Page attributes are set using __set_bit rather than set_bit as
      it normally called under a spinlock so the extra atomicity is not
      needed.
      
      However there are two places where we might set or clear page
      attributes without holding the spinlock.
      So add the spinlock in those cases.
      
      This might be the cause of occasional reports that bits a aren't
      getting clear properly - theory is that BITMAP_PAGE_PENDING gets lost
      when BITMAP_PAGE_NEEDWRITE is set or cleared.  This is an
      inconvenience, not a threat to data safety.
      Signed-off-by: NNeilBrown <neilb@suse.de>
      7c8f4247
  3. 08 11月, 2011 30 次提交
  4. 07 11月, 2011 7 次提交