block: ensure bios return from blk_get_request are properly initialized

blk_get_request is used for BLOCK_PC and similar passthrough requests.
Currently we always need to call blk_rq_set_block_pc or an open coded
version of it to allow appending bios using the request mapping helpers
later on, which is a somewhat awkward API.  Instead move the
initialization part of blk_rq_set_block_pc into blk_get_request, so that
we always have a safe to use request.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 7 insertions, 5 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index dd325638e102..4d8794925fe9 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1294,10 +1294,15 @@ static struct request *blk_old_get_request(struct request_queue *q, int rw,
 
         spin_lock_irq(q->queue_lock);
         rq = get_request(q, rw, 0, NULL, gfp_mask);
-        if (IS_ERR(rq))
+        if (IS_ERR(rq)) {
                 spin_unlock_irq(q->queue_lock);
-        /* q->queue_lock is unlocked at this point */
+                return rq;
+        }
 
+        /* q->queue_lock is unlocked at this point */
+        rq->__data_len = 0;
+        rq->__sector = (sector_t) -1;
+        rq->bio = rq->biotail = NULL;
         return rq;
 }
 
@@ -1377,9 +1382,6 @@ EXPORT_SYMBOL(blk_make_request);
 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));
 }
 EXPORT_SYMBOL(blk_rq_set_block_pc);