This adds a flag that tells the file system that this is a high priority
request for which it's worth to poll the hardware. The flag is purely
advisory and can be ignored if not supported.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Stephen Bates <stephen.bates@pmcs.com> Tested-by: Stephen Bates <stephen.bates@pmcs.com> Acked-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>