blk-mq: avoid infinite recursion with the FUA flag

We should not insert requests into the flush state machine from
blk_mq_insert_request.  All incoming flush requests come through
blk_{m,s}q_make_request and are handled there, while blk_execute_rq_nowait
should only be called for BLOCK_PC requests.  All other callers
deal with requests that already went through the flush statemchine
and shouldn't be reinserted into it.

Reported-by: Robert Elliott  <Elliott@hp.com>
Debugged-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

2 files changed, 4 insertions, 8 deletions

diff --git a/block/blk-exec.c b/block/blk-exec.c
index f4d27b12c90b..9924725fa50d 100644
--- a/block/blk-exec.c
+++ b/block/blk-exec.c
@@ -56,6 +56,7 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
         bool is_pm_resume;
 
         WARN_ON(irqs_disabled());
+        WARN_ON(rq->cmd_type == REQ_TYPE_FS);
 
         rq->rq_disk = bd_disk;
         rq->end_io = done;
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 1583ed28ea03..a7d70a1bbf36 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -963,14 +963,9 @@ void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
 
         hctx = q->mq_ops->map_queue(q, ctx->cpu);
 
-        if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA) &&
-            !(rq->cmd_flags & (REQ_FLUSH_SEQ))) {
-                blk_insert_flush(rq);
-        } else {
-                spin_lock(&ctx->lock);
-                __blk_mq_insert_request(hctx, rq, at_head);
-                spin_unlock(&ctx->lock);
-        }
+        spin_lock(&ctx->lock);
+        __blk_mq_insert_request(hctx, rq, at_head);
+        spin_unlock(&ctx->lock);
 
         if (run_queue)
                 blk_mq_run_hw_queue(hctx, async);