linux-kernel - [PATCH v3 3/7] scsi: target: Add helper to setup atomic values from block

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Message-ID: <20251020103820.2917593-4-john.g.garry@oracle.com>
Date: Mon, 20 Oct 2025 10:38:16 +0000
From: John Garry <john.g.garry@...cle.com>
To: martin.petersen@...cle.com
Cc: target-devel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-scsi@...r.kernel.org, michael.christie@...cle.com,
        John Garry <john.g.garry@...cle.com>
Subject: [PATCH v3 3/7] scsi: target: Add helper to setup atomic values from block_device

From: Mike Christie <michael.christie@...cle.com>

This adds a helper function that sets up the atomic value based on a
block_device similar to what we do for unmap.

Signed-off-by: Mike Christie <michael.christie@...cle.com>
jpg: Set atomic alignment, drop atomic_supported reference
Signed-off-by: John Garry <john.g.garry@...cle.com>
---
 drivers/target/target_core_device.c  | 17 +++++++++++++++++
 include/target/target_core_backend.h |  2 ++
 2 files changed, 19 insertions(+)

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 83fe3d9a9681c..39a2d9c3eb9e1 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -840,6 +840,23 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
 	return NULL;
 }
 
+void target_configure_write_atomic_from_bdev(struct se_dev_attrib *attrib,
+					     struct block_device *bdev)
+{
+	struct request_queue *q = bdev_get_queue(bdev);
+	int block_size = bdev_logical_block_size(bdev);
+
+	if (!bdev_can_atomic_write(bdev))
+		return;
+
+	attrib->atomic_max_len = queue_atomic_write_max_bytes(q) / block_size;
+	attrib->atomic_granularity = attrib->atomic_alignment =
+		queue_atomic_write_unit_min_bytes(q) / block_size;
+	attrib->atomic_max_with_boundary = 0;
+	attrib->atomic_max_boundary = 0;
+}
+EXPORT_SYMBOL_GPL(target_configure_write_atomic_from_bdev);
+
 /*
  * Check if the underlying struct block_device supports discard and if yes
  * configure the UNMAP parameters.
diff --git a/include/target/target_core_backend.h b/include/target/target_core_backend.h
index d394306f8f490..e32de80854b6a 100644
--- a/include/target/target_core_backend.h
+++ b/include/target/target_core_backend.h
@@ -123,6 +123,8 @@ bool target_sense_desc_format(struct se_device *dev);
 sector_t target_to_linux_sector(struct se_device *dev, sector_t lb);
 bool target_configure_unmap_from_bdev(struct se_dev_attrib *attrib,
 				      struct block_device *bdev);
+void target_configure_write_atomic_from_bdev(struct se_dev_attrib *attrib,
+					     struct block_device *bdev);
 
 static inline bool target_dev_configured(struct se_device *se_dev)
 {
-- 
2.43.5