block: WARN in __blk_put_request() for potential bio leak

Put a WARN_ON in __blk_put_request if it is about to
leak bio(s). This is a serious bug that can happen in error
handling code paths.

For this to work I have fixed a couple of places in block/ where
request->bio != NULL ownership was not honored. And a small cleanup
at sg_io() while at it.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 7b63c9b6333..996ed906d8c 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1062,6 +1062,9 @@ void __blk_put_request(struct request_queue *q, struct request *req)
 
         elv_completed_request(q, req);
 
+        /* this is a bio leak */
+        WARN_ON(req->bio != NULL);
+
         /*
          * Request may not have originated from ll_rw_blk. if not,
          * it didn't come out of our reserved rq pools