block/bfq-ioc.c

   1 /*
   2  * BFQ: I/O context handling.
   3  *
   4  * Based on ideas and code from CFQ:
   5  * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
   6  *
   7  * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
   8  *                    Paolo Valente <paolo.valente@unimore.it>
   9  */
  10
  11 /**
  12  * icq_to_bic - convert iocontext queue structure to bfq_io_cq.
  13  * @icq: the iocontext queue.
  14  */
  15 static inline struct bfq_io_cq *icq_to_bic(struct io_cq *icq)
  16 {
  17         /* bic->icq is the first member, %NULL will convert to %NULL */
  18         return container_of(icq, struct bfq_io_cq, icq);
  19 }
  20
  21 /**
  22  * bfq_bic_lookup - search into @ioc a bic associated to @bfqd.
  23  * @bfqd: the lookup key.
  24  * @ioc: the io_context of the process doing I/O.
  25  *
  26  * Queue lock must be held.
  27  */
  28 static inline struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd,
  29                                                struct io_context *ioc)
  30 {
  31         if(ioc)
  32                 return icq_to_bic(ioc_lookup_icq(ioc, bfqd->queue));
  33         return NULL;
  34 }