Re: [PATCH 21/21] nvme: Support atomic writes

From: John Garry
Date: Thu Oct 05 2023 - 11:45:49 EST


On 04/10/2023 12:39, Pankaj Raghav wrote:
+++ b/drivers/nvme/host/core.c
@@ -1926,6 +1926,35 @@ static void nvme_update_disk_info(struct gendisk *disk,
blk_queue_io_min(disk->queue, phys_bs);
blk_queue_io_opt(disk->queue, io_opt);
+ atomic_bs = rounddown_pow_of_two(atomic_bs);
+ if (id->nsfeat & NVME_NS_FEAT_ATOMICS && id->nawupf) {
+ if (id->nabo) {
+ dev_err(ns->ctrl->device, "Support atomic NABO=%x\n",
+ id->nabo);
+ } else {
+ u32 boundary = 0;
+
+ if (le16_to_cpu(id->nabspf))
+ boundary = (le16_to_cpu(id->nabspf) + 1) * bs;
+
+ if (is_power_of_2(boundary) || !boundary) {

note to self/Alan: boundary just needs to be multiple of atomic write unit max, and not necessarily a power-of-2

+ blk_queue_atomic_write_max_bytes(disk->queue, atomic_bs);
+ blk_queue_atomic_write_unit_min_sectors(disk->queue, 1);
+ blk_queue_atomic_write_unit_max_sectors(disk->queue,
+ atomic_bs / bs);
blk_queue_atomic_write_unit_[min| max]_sectors expects sectors (512 bytes unit)
as input but no conversion is done here from device logical block size
to SECTORs.

Yeah, you are right. I think that we can just use:

blk_queue_atomic_write_unit_max_sectors(disk->queue,
atomic_bs >> SECTOR_SHIFT);

Thanks,
John

+ blk_queue_atomic_write_boundary_bytes(disk->queue, boundary);
+ } else {
+ dev_err(ns->ctrl->device, "Unsupported atomic boundary=0x%x\n",
+ boundary);
+ }