scsi: Do not rely on blk-mq for double completions

The scsi timeout error handling had been directly updating the block
layer's request state to prevent a error handling and a natural completion
from completing the same request twice. Fix this layering violation
by having scsi control the fate of its commands with scsi owned flags
rather than use blk-mq's.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 12 insertions, 1 deletions

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 0df15cb738d2..0dbf25512778 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1642,8 +1642,18 @@ static blk_status_t scsi_mq_prep_fn(struct request *req)
 
 static void scsi_mq_done(struct scsi_cmnd *cmd)
 {
+        if (unlikely(test_and_set_bit(SCMD_STATE_COMPLETE, &cmd->state)))
+                return;
         trace_scsi_dispatch_cmd_done(cmd);
-        blk_mq_complete_request(cmd->request);
+
+        /*
+         * If the block layer didn't complete the request due to a timeout
+         * injection, scsi must clear its internal completed state so that the
+         * timeout handler will see it needs to escalate its own error
+         * recovery.
+         */
+        if (unlikely(!blk_mq_complete_request(cmd->request)))
+                clear_bit(SCMD_STATE_COMPLETE, &cmd->state);
 }
 
 static void scsi_mq_put_budget(struct blk_mq_hw_ctx *hctx)
@@ -1702,6 +1712,7 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
         if (!scsi_host_queue_ready(q, shost, sdev))
                 goto out_dec_target_busy;
 
+        clear_bit(SCMD_STATE_COMPLETE, &cmd->state);
         if (!(req->rq_flags & RQF_DONTPREP)) {
                 ret = scsi_mq_prep_fn(req);
                 if (ret != BLK_STS_OK)