This patch fixes a bug where the buffer was being freed as soon as
 submission to HW is done.
Signed-off-by: NJayamohan Kallickal <jayamohank@serverengines.com>
Reviewed-by: NMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: NJames Bottomley <James.Bottomley@suse.de>