null_blk: add an usage for shared tags in documentation
Add usage explanation for a shared_tags, introduced by commit:
82f402fefa50 ("null_blk: add support for shared tags")
Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com>
Reworded slightly.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/Documentation/block/null_blk.txt b/Documentation/block/null_blk.txt
index fcf7f84..733927a 100644
--- a/Documentation/block/null_blk.txt
+++ b/Documentation/block/null_blk.txt
@@ -77,3 +77,8 @@
no_sched=[0/1]: Default: 0
0: nullb* use default blk-mq io scheduler.
1: nullb* doesn't use io scheduler.
+
+shared_tags=[0/1]: Default: 0
+ 0: Tag set is not shared.
+ 1: Tag set shared between devices for blk-mq. Only makes sense with
+ nr_devices > 1, otherwise there's no tag set to share.