linux-kernel - [RFC PATCH v2 2/8] nvme: set BLK_FEAT_WRITE_ZEROES

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Message-Id: <20250115114637.2705887-3-yi.zhang@huaweicloud.com>
Date: Wed, 15 Jan 2025 19:46:31 +0800
From: Zhang Yi <yi.zhang@...weicloud.com>
To: linux-fsdevel@...r.kernel.org,
	linux-ext4@...r.kernel.org,
	linux-block@...r.kernel.org,
	dm-devel@...ts.linux.dev,
	linux-nvme@...ts.infradead.org,
	linux-scsi@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	hch@....de,
	tytso@....edu,
	djwong@...nel.org,
	yi.zhang@...wei.com,
	yi.zhang@...weicloud.com,
	chengzhihao1@...wei.com,
	yukuai3@...wei.com,
	yangerkun@...wei.com
Subject: [RFC PATCH v2 2/8] nvme: set BLK_FEAT_WRITE_ZEROES_UNMAP if device supports DEAC bit

From: Zhang Yi <yi.zhang@...wei.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@...wei.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 a970168a3014..8a359370154d 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2210,22 +2210,25 @@ 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);
-		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);
+		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);
-- 
2.39.2