null_blk: don't cap max_hw_sectors to BLK_DEF_MAX_SECTORS

null_blk has some rather odd capping of the max_hw_sectors value to
BLK_DEF_MAX_SECTORS, which doesn't make sense - max_hw_sector is the
hardware limit, and BLK_DEF_MAX_SECTORS despite the confusing name is the
default cap for the max_sectors field used for normal file system I/O.

Remove all the capping, and simply leave it to the block layer or
user to take up or not all of that for file system I/O.

Fixes: ea17fd3 ("null_blk: Allow controlling max_hw_sectors limit")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20231227092305.279567-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Christoph Hellwig

drivers/block/null_blk/main.c

@@ -2186,10 +2186,8 @@ static int null_add_dev(struct nullb_device *dev)
 
 	blk_queue_logical_block_size(nullb->q, dev->blocksize);
 	blk_queue_physical_block_size(nullb->q, dev->blocksize);
-	if (!dev->max_sectors)
-		dev->max_sectors = queue_max_hw_sectors(nullb->q);
-	dev->max_sectors = min(dev->max_sectors, BLK_DEF_MAX_SECTORS);
-	blk_queue_max_hw_sectors(nullb->q, dev->max_sectors);
+	if (dev->max_sectors)
+		blk_queue_max_hw_sectors(nullb->q, dev->max_sectors);
 
 	if (dev->virt_boundary)
 		blk_queue_virt_boundary(nullb->q, PAGE_SIZE - 1);
@@ -2289,12 +2287,6 @@ static int __init null_init(void)
 		g_bs = PAGE_SIZE;
 	}
 
-	if (g_max_sectors > BLK_DEF_MAX_SECTORS) {
-		pr_warn("invalid max sectors\n");
-		pr_warn("defaults max sectors to %u\n", BLK_DEF_MAX_SECTORS);
-		g_max_sectors = BLK_DEF_MAX_SECTORS;
-	}
-
 	if (g_home_node != NUMA_NO_NODE && g_home_node >= nr_online_nodes) {
 		pr_err("invalid home_node value\n");
 		g_home_node = NUMA_NO_NODE;