Messages in this thread | | | Date | Mon, 15 Aug 2011 11:10:42 -0400 | From | Konrad Rzeszutek Wilk <> | Subject | Re: [Xen-devel] Re: [patch] xen-blkback: sync I/O after backend disconnected |
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On Mon, Aug 15, 2011 at 10:46:10AM -0400, Christoph Hellwig wrote: > On Mon, Aug 15, 2011 at 12:55:02PM +0800, Joe Jin wrote: > > When backend disconnect, sync IO requests to the disk. > > Care to explain why?
I was thinking it might be a good idea to do that when a disk (file, LVM, real block device) is released from a guest just in case there is some outstanding I/Os. But then I realized that we bypasses the page cache anyhow - so there should be no outstanding I/O requests - unless they are in the disk queue.
And the guest would normally issues a FLUSH when unmounting the disk. Hm, I wonder what the conditions are when we forcibly kill the guest - there might be outstanding I/Os in the disk's cache - at which point we should probably sync the write cache, no?
> > Also you'll just need a sync_blockdev, fsync_bdev does far to many > things that don't make any sense when you don't have a file system > mounted on a device. > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel
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