On Wed, Sep 23, 2015 at 12:41:55AM -0400, Dan Williams wrote: > Enable DAX to use a reference count for keeping the virtual address > returned by ->direct_access() valid for the duration of its usage in > fs/dax.c, or otherwise hold off blk_cleanup_queue() while > pmem_make_request is active. The blk-mq code is already in a position > to need low overhead referece counting for races against request_queue > destruction (blk_cleanup_queue()). Given DAX-enabled block drivers do > not enable blk-mq, share the storage in 'struct request_queue' between > the two implementations. Can we just move the refcounting to common code with the same field name, and even initialize it for non-mq, non-dax queues but just never tage a reference there (for now)? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>