blk-mq: Add a flag for reserved requests

Add a flag for reserved requests so that drivers may know this for any
special handling.

Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/1657109034-206040-3-git-send-email-john.garry@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 15c7c5c..a00e43c 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -475,6 +475,9 @@ retry:
        if (!(data->rq_flags & RQF_ELV))
                blk_mq_tag_busy(data->hctx);
 
+       if (data->flags & BLK_MQ_REQ_RESERVED)
+               data->rq_flags |= RQF_RESV;
+
        /*
         * Try batched alloc if we want more than 1 tag.
         */
@@ -589,6 +592,9 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
        else
                data.rq_flags |= RQF_ELV;
 
+       if (flags & BLK_MQ_REQ_RESERVED)
+               data.rq_flags |= RQF_RESV;
+
        ret = -EWOULDBLOCK;
        tag = blk_mq_get_tag(&data);
        if (tag == BLK_MQ_NO_TAG)

diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 43aad0d..7c62b7f 100644 (file)
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -57,6 +57,7 @@ typedef __u32 __bitwise req_flags_t;
 #define RQF_TIMED_OUT          ((__force req_flags_t)(1 << 21))
 /* queue has elevator attached */
 #define RQF_ELV                        ((__force req_flags_t)(1 << 22))
+#define RQF_RESV                       ((__force req_flags_t)(1 << 23))
 
 /* flags that prevent us from merging requests: */
 #define RQF_NOMERGE_FLAGS \
@@ -825,6 +826,11 @@ static inline bool blk_mq_need_time_stamp(struct request *rq)
        return (rq->rq_flags & (RQF_IO_STAT | RQF_STATS | RQF_ELV));
 }
 
+static inline bool blk_mq_is_reserved_rq(struct request *rq)
+{
+       return rq->rq_flags & RQF_RESV;
+}
+
 /*
  * Batched completions only work when there is no I/O error and no special
  * ->end_io handler.