[RFC PATCH -next v3 02/10] nvme: set BLK_FEAT_WRITE_ZEROES_UNMAP if device supports DEAC bit

Zhang Yi
2025-03-18T07:44:13Z

From: Zhang Yi <yi.zhang@huawei.com>

When the device supports the Write Zeroes command and the DEAC bit, it
indicates that the deallocate bit in the Write Zeroes command is
supported, and the bytes read from a deallocated logical block are
zeroes. This means the device supports unmap Write Zeroes, so set the
BLK_FEAT_WRITE_ZEROES_UNMAP feature to the device's queue limit.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
drivers/nvme/host/core.c | 21 ++++++++++++---------
1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 24c3e1765d49..3af6a50f07ec 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2223,22 +2223,25 @@ static int nvme_update_ns_info_block(struct nvme_ns *ns,
if (!nvme_init_integrity(ns->head, &lim, info))
capacity = 0;

- ret = queue_limits_commit_update(ns->disk->queue, &lim);
- if (ret) {
- blk_mq_unfreeze_queue(ns->disk->queue, memflags);
- goto out;
- }
-
- set_capacity_and_notify(ns->disk, capacity);
-
/*
* Only set the DEAC bit if the device guarantees that reads from
* deallocated data return zeroes. While the DEAC bit does not
* require that, it must be a no-op if reads from deallocated data
* do not return zeroes.
*/
- if ((id->dlfeat & 0x7) == 0x1 && (id->dlfeat & (1 << 3)))
+ if ((id->dlfeat & 0x7) == 0x1 && (id->dlfeat & (1 << 3))) {
ns->head->features |= NVME_NS_DEAC;
+ if (lim.max_write_zeroes_sectors)
+ lim.features |= BLK_FEAT_WRITE_ZEROES_UNMAP;
+ }
+
+ ret = queue_limits_commit_update(ns->disk->queue, &lim);
+ if (ret) {
+ blk_mq_unfreeze_queue(ns->disk->queue, memflags);
+ goto out;
+ }
+
+ set_capacity_and_notify(ns->disk, capacity);
set_disk_ro(ns->disk, nvme_ns_is_readonly(ns, info));
set_bit(NVME_NS_READY, &ns->flags);
blk_mq_unfreeze_queue(ns->disk->queue, memflags);
--
2.46.1