blk-mq: Allow requests to never expire

Some types of requests may be started that are not gauranteed to ever
complete. This adds a request flag that a driver can use so mark the
request as such.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 261ccd8..78324a2 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -619,7 +619,7 @@ void blk_mq_rq_timed_out(struct request *req, bool reserved)
                break;
        }
 }
-               
+
 static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
                struct request *rq, void *priv, bool reserved)
 {
@@ -627,6 +627,8 @@ static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
 
        if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
                return;
+       if (rq->cmd_flags & REQ_NO_TIMEOUT)
+               return;
 
        if (time_after_eq(jiffies, rq->deadline)) {
                if (!blk_mark_rq_complete(rq))

diff --git a/block/blk-timeout.c b/block/blk-timeout.c
index 56c0258..246dfb1 100644 (file)
--- a/block/blk-timeout.c
+++ b/block/blk-timeout.c
@@ -190,6 +190,9 @@ void blk_add_timer(struct request *req)
        struct request_queue *q = req->q;
        unsigned long expiry;
 
+       if (req->cmd_flags & REQ_NO_TIMEOUT)
+               return;
+
        /* blk-mq has its own handler, so we don't need ->rq_timed_out_fn */
        if (!q->mq_ops && !q->rq_timed_out_fn)
                return;

diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 445d592..c294e3e 100644 (file)
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -190,6 +190,7 @@ enum rq_flag_bits {
        __REQ_PM,               /* runtime pm request */
        __REQ_HASHED,           /* on IO scheduler merge hash */
        __REQ_MQ_INFLIGHT,      /* track inflight for MQ */
+       __REQ_NO_TIMEOUT,       /* requests may never expire */
        __REQ_NR_BITS,          /* stops here */
 };
 
@@ -243,5 +244,6 @@ enum rq_flag_bits {
 #define REQ_PM                 (1ULL << __REQ_PM)
 #define REQ_HASHED             (1ULL << __REQ_HASHED)
 #define REQ_MQ_INFLIGHT                (1ULL << __REQ_MQ_INFLIGHT)
+#define REQ_NO_TIMEOUT         (1ULL << __REQ_NO_TIMEOUT)
 
 #endif /* __LINUX_BLK_TYPES_H */