convert xen-blkfront to atomic queue limit updates

[Christoph Hellwig <hch@xxxxxx>]

Hi all,

this series converts xen-blkfront to the new atomic queue limits update
API in the block tree.  I don't have a Xen setup so this is compile
tested only.

Diffstat:
 xen-blkfront.c |   53 +++++++++++++++++++++++++++--------------------------
 1 file changed, 27 insertions(+), 26 deletions(-)