[PATCH] nvme: honor NVME_QUIRK_DEALLOCATE_ZEROES for unmap Write Zeroes

[Robert Pang <robertpang@google.com>]

Currently, the NVMe driver sets max_hw_wzeroes_unmap_sectors to indicate the
support for unmap Write Zeroes based strictly on the Deallocate Logical Block
Features (dlfeat) in the Identify Namespace data (commit 545fb46e5bc6 "nvme: set
max_hw_wzeroes_unmap_sectors if device supports DEAC bit").

However, certain devices already use the NVME_QUIRK_DEALLOCATE_ZEROES quirk to
indicate that they deterministically return zeroes after a deallocate/discard
operation to support the Write Zeroes operation in nvme_setup_write_zeroes().
For these devices, it is appropriate to treat them as supporting the unmap Write
Zeroes operation.

Update nvme_update_disk_info() to allow the presence of the DEALLOCATE_ZEROES
quirk (combined with DSM support) to set max_hw_wzeroes_unmap_sectors to enable
the support for unmap Write Zeroes. This ensures consistency with how these
devices are handled elsewhere in the driver.

Signed-off-by: Robert Pang <robertpang@google.com>
Link: https://lore.kernel.org/linux-ext4/20260225000531.3658802-1-robertpang@google.com/T/#m5e776f78ecb7631372d82a5cb3d11f8f1f8afe06
---
 drivers/nvme/host/core.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index f5ebcaa2f859..3f5dd3f867e9 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2120,9 +2120,10 @@ static bool nvme_update_disk_info(struct nvme_ns *ns, struct nvme_id_ns *id,
 	lim->io_min = phys_bs;
 	lim->io_opt = io_opt;
 	if ((ns->ctrl->quirks & NVME_QUIRK_DEALLOCATE_ZEROES) &&
-	    (ns->ctrl->oncs & NVME_CTRL_ONCS_DSM))
+	    (ns->ctrl->oncs & NVME_CTRL_ONCS_DSM)) {
 		lim->max_write_zeroes_sectors = UINT_MAX;
-	else
+		lim->max_hw_wzeroes_unmap_sectors = UINT_MAX;
+	} else
 		lim->max_write_zeroes_sectors = ns->ctrl->max_zeroes_sectors;
 	return valid;
 }
-- 
2.53.0.473.g4a7958ca14-goog