null_blk: remove hardcoded null_alloc_page() param

Only caller of null_alloc_page() is null_insert_page() unconditionally
sets only parameter to GFP_NOIO and that is statically hard-coded in
null_blk. There is no point in having statically hardcoded function
parameter.

Remove the unnecessary parameter gfp_flags and adjust the code, so it
can retain existing behavior null_alloc_page() with GFP_NOIO.
Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220222152852.26043-2-kch@nvidia.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/null_blk/main.c

@@ -777,15 +777,15 @@ static void null_complete_rq(struct request *rq)
 	end_cmd(blk_mq_rq_to_pdu(rq));
 }
 
-static struct nullb_page *null_alloc_page(gfp_t gfp_flags)
+static struct nullb_page *null_alloc_page(void)
 {
 	struct nullb_page *t_page;
 
-	t_page = kmalloc(sizeof(struct nullb_page), gfp_flags);
+	t_page = kmalloc(sizeof(struct nullb_page), GFP_NOIO);
 	if (!t_page)
 		goto out;
 
-	t_page->page = alloc_pages(gfp_flags, 0);
+	t_page->page = alloc_pages(GFP_NOIO, 0);
 	if (!t_page->page)
 		goto out_freepage;
 
@@ -932,7 +932,7 @@ static struct nullb_page *null_insert_page(struct nullb *nullb,
 
 	spin_unlock_irq(&nullb->lock);
 
-	t_page = null_alloc_page(GFP_NOIO);
+	t_page = null_alloc_page();
 	if (!t_page)
 		goto out_lock;