blk-mq: bump max tag depth to 10K tags

For some scsi-mq cases, the tag map can be huge. So increase the
max number of tags we support.

Additionally, don't fail with EINVAL if a user requests too many
tags. Warn that the tag depth has been adjusted down, and store
the new value inside the tag_set passed in.

Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 4e4cd6208052..a6ee74e27957 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1967,13 +1967,19 @@ static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
         return NOTIFY_OK;
 }
 
+/*
+ * Alloc a tag set to be associated with one or more request queues.
+ * May fail with EINVAL for various error conditions. May adjust the
+ * requested depth down, if if it too large. In that case, the set
+ * value will be stored in set->queue_depth.
+ */
 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
 {
         int i;
 
         if (!set->nr_hw_queues)
                 return -EINVAL;
-        if (!set->queue_depth || set->queue_depth > BLK_MQ_MAX_DEPTH)
+        if (!set->queue_depth)
                 return -EINVAL;
         if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
                 return -EINVAL;
@@ -1981,6 +1987,11 @@ int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
         if (!set->nr_hw_queues || !set->ops->queue_rq || !set->ops->map_queue)
                 return -EINVAL;
 
+        if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
+                pr_info("blk-mq: reduced tag depth to %u\n",
+                        BLK_MQ_MAX_DEPTH);
+                set->queue_depth = BLK_MQ_MAX_DEPTH;
+        }
 
         set->tags = kmalloc_node(set->nr_hw_queues *
                                  sizeof(struct blk_mq_tags *),