blk-mq: fix racy updates of rq->errors
blk_mq_complete_request may be a no-op if the request has already
been completed by others means (e.g. a timeout or cancellation), but
currently drivers have to set rq->errors before calling
blk_mq_complete_request, which might leave us with the wrong error value.
Add an error parameter to blk_mq_complete_request so that we can
defer setting rq->errors until we known we won the race to complete the
request.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index f9889b6..674f800 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1486,17 +1486,16 @@
{
const bool write = cmd->rq->cmd_flags & REQ_WRITE;
struct loop_device *lo = cmd->rq->q->queuedata;
- int ret = -EIO;
+ int ret = 0;
- if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY))
+ if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) {
+ ret = -EIO;
goto failed;
+ }
ret = do_req_filebacked(lo, cmd->rq);
-
failed:
- if (ret)
- cmd->rq->errors = -EIO;
- blk_mq_complete_request(cmd->rq);
+ blk_mq_complete_request(cmd->rq, ret ? -EIO : 0);
}
static void loop_queue_write_work(struct work_struct *work)
