add a struct request pointer to the request structure

This adds a struct request pointer to the request structure for the
second data phase (bidi for now). A request queue supporting bidi
requests sets QUEUE_FLAG_BIDI. This prevents sending bidi requests to
a non-bidi queue.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index ef42bb2b12b6dd89b0edc1734485e66147920759..11e4235d0b0c8e984adc507a80657382640db248 100644 (file)
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -256,6 +256,7 @@ static void rq_init(request_queue_t *q, struct request *rq)
        rq->end_io = NULL;
        rq->end_io_data = NULL;
        rq->completion_data = NULL;
+       rq->next_rq = NULL;
 }
 
 /**

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 24b474e05a4457ffe6fa518d706d40a24921db13..b32564a1e105c4220d14d988e6530a141b46be76 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -317,6 +317,9 @@ struct request {
         */
        rq_end_io_fn *end_io;
        void *end_io_data;
+
+       /* for bidi */
+       struct request *next_rq;
 };
 
 /*
@@ -486,6 +489,7 @@ struct request_queue
 #define QUEUE_FLAG_REENTER     6       /* Re-entrancy avoidance */
 #define QUEUE_FLAG_PLUGGED     7       /* queue is plugged */
 #define QUEUE_FLAG_ELVSWITCH   8       /* don't use elevator, just do FIFO */
+#define QUEUE_FLAG_BIDI                9       /* queue supports bidi requests */
 
 enum {
        /*
@@ -550,6 +554,7 @@ enum {
 #define blk_sorted_rq(rq)      ((rq)->cmd_flags & REQ_SORTED)
 #define blk_barrier_rq(rq)     ((rq)->cmd_flags & REQ_HARDBARRIER)
 #define blk_fua_rq(rq)         ((rq)->cmd_flags & REQ_FUA)
+#define blk_bidi_rq(rq)                ((rq)->next_rq != NULL)
 
 #define list_entry_rq(ptr)     list_entry((ptr), struct request, queuelist)