On Fri, 23 Mar 2012, Kasatkin, Dmitry wrote: > When using dm-bufio and dm-io in general, how to ensure that all dirty Regarding dm-io, you don't have to flush dirty buffers because dm-io does no caching. You only need to flush hardware disk cache with blkdev_issue_flush. > At the moment, I have reboot notifier which does the following > > dm_bufio_write_dirty_buffers(d->bufio); > sync_blockdev(d->dev->bdev); > blkdev_issue_flush(d->dev->bdev, GFP_KERNEL, NULL); > > without first line on the next boot I got corrupted/not updated blocks. > and I am not sure if I need last 2 lines... You can drop sync_blockdev(d->dev->bdev) --- sync_blockdev flushes kernel buffer cache and dm-bufio doesn't use the kernel buffer cache (you only need sync_blockdev if you use kernel buffer cache on this device for something else). If you drop sync_blockdev, you can also drop blkdev_issue_flush, because dm_bufio_write_dirty_buffers already issues the flush request. BTW. how are you going to deal with kernel crashes or power faults? It is much better to use journaling, phase tree, crash counts or other method to maintain metadata integrity insted of reboot notifier --- these methods maintain integrity even in case of unexpected crash. Mikulas -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
