loop: Only freeze block queue when needed.

__loop_update_dio() can be called as a part of loop_set_fd(), when the
block queue is not yet up and running; avoid freezing the block queue in
that case, since that is an expensive operation.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Martijn Coenen <maco@android.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 93b8d60..a42c49e 100644 (file)
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -214,7 +214,8 @@ static void __loop_update_dio(struct loop_device *lo, bool dio)
         * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup
         * will get updated by ioctl(LOOP_GET_STATUS)
         */
-       blk_mq_freeze_queue(lo->lo_queue);
+       if (lo->lo_state == Lo_bound)
+               blk_mq_freeze_queue(lo->lo_queue);
        lo->use_dio = use_dio;
        if (use_dio) {
                blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, lo->lo_queue);
@@ -223,7 +224,8 @@ static void __loop_update_dio(struct loop_device *lo, bool dio)
                blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
                lo->lo_flags &= ~LO_FLAGS_DIRECT_IO;
        }
-       blk_mq_unfreeze_queue(lo->lo_queue);
+       if (lo->lo_state == Lo_bound)
+               blk_mq_unfreeze_queue(lo->lo_queue);
 }
 
 static int