block: make rq_init() do a full memset()

This requires moving rq_init() from get_request() to blk_alloc_request().
The upside is that we can now require an rq_init() from any path that
wishes to hand the request to the block layer.

rq_init() will be exported for the code that uses struct request
without blk_get_request.

This is a preparation for large command support, which needs to
initialize struct request in a proper way (that is, just doing a
memset() will not work).

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

2 files changed, 5 insertions, 32 deletions

diff --git a/block/blk-barrier.c b/block/blk-barrier.c
index 55c5f1fc4f1f..722140ac175a 100644
--- a/block/blk-barrier.c
+++ b/block/blk-barrier.c
@@ -143,10 +143,8 @@ static void queue_flush(struct request_queue *q, unsigned which)
                 end_io = post_flush_end_io;
         }
 
-        rq->cmd_flags = REQ_HARDBARRIER;
         rq_init(q, rq);
-        rq->elevator_private = NULL;
-        rq->elevator_private2 = NULL;
+        rq->cmd_flags = REQ_HARDBARRIER;
         rq->rq_disk = q->bar_rq.rq_disk;
         rq->end_io = end_io;
         q->prepare_flush_fn(q, rq);
@@ -167,14 +165,11 @@ static inline struct request *start_ordered(struct request_queue *q,
         blkdev_dequeue_request(rq);
         q->orig_bar_rq = rq;
         rq = &q->bar_rq;
-        rq->cmd_flags = 0;
         rq_init(q, rq);
         if (bio_data_dir(q->orig_bar_rq->bio) == WRITE)
                 rq->cmd_flags |= REQ_RW;
         if (q->ordered & QUEUE_ORDERED_FUA)
                 rq->cmd_flags |= REQ_FUA;
-        rq->elevator_private = NULL;
-        rq->elevator_private2 = NULL;
         init_request_from_bio(rq, q->orig_bar_rq->bio);
         rq->end_io = bar_end_io;
 
diff --git a/block/blk-core.c b/block/blk-core.c
index 2a438a93f723..e447799256d6 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -107,40 +107,18 @@ struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
 }
 EXPORT_SYMBOL(blk_get_backing_dev_info);
 
-/*
- * We can't just memset() the structure, since the allocation path
- * already stored some information in the request.
- */
 void rq_init(struct request_queue *q, struct request *rq)
 {
+        memset(rq, 0, sizeof(*rq));
+
         INIT_LIST_HEAD(&rq->queuelist);
         INIT_LIST_HEAD(&rq->donelist);
         rq->q = q;
         rq->sector = rq->hard_sector = (sector_t) -1;
-        rq->nr_sectors = rq->hard_nr_sectors = 0;
-        rq->current_nr_sectors = rq->hard_cur_sectors = 0;
-        rq->bio = rq->biotail = NULL;
         INIT_HLIST_NODE(&rq->hash);
         RB_CLEAR_NODE(&rq->rb_node);
-        rq->rq_disk = NULL;
-        rq->nr_phys_segments = 0;
-        rq->nr_hw_segments = 0;
-        rq->ioprio = 0;
-        rq->special = NULL;
-        rq->buffer = NULL;
         rq->tag = -1;
-        rq->errors = 0;
         rq->ref_count = 1;
-        rq->cmd_len = 0;
-        memset(rq->cmd, 0, sizeof(rq->cmd));
-        rq->data_len = 0;
-        rq->extra_len = 0;
-        rq->sense_len = 0;
-        rq->data = NULL;
-        rq->sense = NULL;
-        rq->end_io = NULL;
-        rq->end_io_data = NULL;
-        rq->next_rq = NULL;
 }
 
 static void req_bio_endio(struct request *rq, struct bio *bio,
@@ -607,6 +585,8 @@ blk_alloc_request(struct request_queue *q, int rw, int priv, gfp_t gfp_mask)
         if (!rq)
                 return NULL;
 
+        rq_init(q, rq);
+
         /*
          * first three bits are identical in rq->cmd_flags and bio->bi_rw,
          * see bio.h and blkdev.h
@@ -789,8 +769,6 @@ rq_starved:
         if (ioc_batching(q, ioc))
                 ioc->nr_batch_requests--;
 
-        rq_init(q, rq);
-
         blk_add_trace_generic(q, bio, rw, BLK_TA_GETRQ);
 out:
         return rq;