On 2/1/23 15:50, Luis Chamberlain wrote:
On Mon, Jan 30, 2023 at 01:26:51PM -0800, Bart Van Assche wrote:@@ -122,12 +177,17 @@ EXPORT_SYMBOL(blk_queue_bounce_limit); void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors) { struct queue_limits *limits = &q->limits; + unsigned int min_max_hw_sectors = PAGE_SIZE >> SECTOR_SHIFT; unsigned int max_sectors;- if ((max_hw_sectors << 9) < PAGE_SIZE) {- max_hw_sectors = 1 << (PAGE_SHIFT - 9); - printk(KERN_INFO "%s: set to minimum %d\n", - __func__, max_hw_sectors); + if (max_hw_sectors < min_max_hw_sectors) { + blk_enable_sub_page_limits(limits); + min_max_hw_sectors = 1; + }Up to this part this a non-functional update, and so why not a separate patch to clarify that.
Will do.
+ + if (max_hw_sectors < min_max_hw_sectors) { + max_hw_sectors = min_max_hw_sectors; + pr_info("%s: set to minimum %u\n", __func__, max_hw_sectors);But if I understand correctly here we're now changing max_hw_sectors from 1 to whatever the driver set on blk_queue_max_hw_sectors() if its smaller than PAGE_SIZE. To determine if this is a functional change it begs the question as to how many block drivers have a max hw sector smaller than the equivalent PAGE_SIZE and wonder if that could regress.
If a block driver passes an argument to blk_queue_max_hw_sectors() or blk_queue_max_segment_size() that is smaller than what is supported by the block layer, data corruption will be triggered if the block driver or the hardware supported by the block driver does not support the larger values chosen by the block layer. Changing limits that will trigger data corruption into limits that may work seems like an improvement to me?
Thanks, Bart.
