blk-mq: allocate flush_rq in blk_mq_init_flush()

It is reasonable to allocate flush req in blk_mq_init_flush().

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/block/blk-flush.c b/block/blk-flush.c
index c8e25768f2e1..55028a707927 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -472,7 +472,16 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
 }
 EXPORT_SYMBOL(blkdev_issue_flush);
 
-void blk_mq_init_flush(struct request_queue *q)
+int blk_mq_init_flush(struct request_queue *q)
 {
+        struct blk_mq_tag_set *set = q->tag_set;
+
         spin_lock_init(&q->mq_flush_lock);
+
+        q->flush_rq = kzalloc(round_up(sizeof(struct request) +
+                                set->cmd_size, cache_line_size()),
+                                GFP_KERNEL);
+        if (!q->flush_rq)
+                return -ENOMEM;
+        return 0;
 }