On Wed, Apr 29, 2015 at 5:32 PM, NeilBrown <neilb@xxxxxxx> wrote: > > bdi_unregister() now contains very little functionality. > > It contains a "WARN_ON" if bdi->dev is NULL. This warning is of no > real consequence as bdi->dev isn't needed by anything else in the function, > and it triggers if > blk_cleanup_queue() -> bdi_destroy() > is called before bdi_unregister, which a subsequent patch will make happen. > So this isn't wanted. > > It also calls bdi_set_min_ratio(). This needs to be called after > writes through the bdi have all been flushed, and before the bdi is destroyed. > Calling it early is better than calling it late as it frees up a global > resource. > > Calling it immediately after bdi_wb_shutdown() in bdi_destroy() > perfectly fits these requirements. > > So bdi_unregister can be discarded with the important content moved to > bdi_destroy, as can the > writeback_bdi_unregister > event which is already not used. > > This is tagged for 'stable' as it is a pre-requisite for a subsequent > patch which moves calls to blk_cleanup_queue() before calls to > del_gendisk(). The commit identified as 'Fixes' removed a lot of > other functionality from bdi_unregister(), and made a change which > necessitated moving the blk_cleanup_queue() calls. > > Reported-by: Mike Snitzer <snitzer@xxxxxxxxxx> > Cc: Christoph Hellwig <hch@xxxxxx> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx (v4.0) > Fixes: c4db59d31e39ea067c32163ac961e9c80198fd37 > Signed-off-by: NeilBrown <neilb@xxxxxxx> > > --- > > Hi again Jens, > would you be able to queue this patch *before* the other one: > block: destroy bdi before blockdev is unregistered. > > If it has to come after I'll need to re-write the text a bit. > If you could give me the commit hash to reference I'll do that. Seems it is after: http://git.kernel.dk/?p=linux-block.git;a=commit;h=6cd18e71 Also, we gave both patches a try internally after seeing the duplicate sysfs warning. You can add: Acked-by: Dan Williams <dan.j.williams@xxxxxxxxx> Tested-by: Nicholas Moulin <nicholas.w.moulin@xxxxxxxxxxxxxxx> ...on the re-send. Thanks Neil! -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
