block: add blk_rq_set_block_pc()

With the optimizations around not clearing the full request at alloc
time, we are leaving some of the needed init for REQ_TYPE_BLOCK_PC
up to the user allocating the request.

Add a blk_rq_set_block_pc() that sets the command type to
REQ_TYPE_BLOCK_PC, and properly initializes the members associated
with this type of request. Update callers to use this function instead
of manipulating rq->cmd_type directly.

Includes fixes from Christoph Hellwig <hch@lst.de> for my half-assed
attempt.

Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 40d654861c33..9aca8c71e70b 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1218,6 +1218,8 @@ struct request *blk_make_request(struct request_queue *q, struct bio *bio,
         if (unlikely(!rq))
                 return ERR_PTR(-ENOMEM);
 
+        blk_rq_set_block_pc(rq);
+
         for_each_bio(bio) {
                 struct bio *bounce_bio = bio;
                 int ret;
@@ -1235,6 +1237,22 @@ struct request *blk_make_request(struct request_queue *q, struct bio *bio,
 EXPORT_SYMBOL(blk_make_request);
 
 /**
+ * blk_rq_set_block_pc - initialize a requeest to type BLOCK_PC
+ * @rq:         request to be initialized
+ *
+ */
+void blk_rq_set_block_pc(struct request *rq)
+{
+        rq->cmd_type = REQ_TYPE_BLOCK_PC;
+        rq->__data_len = 0;
+        rq->__sector = (sector_t) -1;
+        rq->bio = rq->biotail = NULL;
+        memset(rq->__cmd, 0, sizeof(rq->__cmd));
+        rq->cmd = rq->__cmd;
+}
+EXPORT_SYMBOL(blk_rq_set_block_pc);
+
+/**
  * blk_requeue_request - put a request back on queue
  * @q:          request queue where request should be inserted
  * @rq:         request to be inserted