[PATCH v3 11/15] scsi: sd: Support reading atomic write properties from block limits VPD

[John Garry]

Also update block layer request queue sysfs properties.

See sbc4r22 section 6.6.4 - Block limits VPD page.

Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
---
 drivers/scsi/sd.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++-
 drivers/scsi/sd.h |  8 ++++++
 2 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 0833b3e6aa6e..32dfb5327f92 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -916,6 +916,65 @@ static blk_status_t sd_setup_unmap_cmnd(struct scsi_cmnd *cmd)
 	return scsi_alloc_sgtables(cmd);
 }
 
+static void sd_config_atomic(struct scsi_disk *sdkp)
+{
+	unsigned int logical_block_size = sdkp->device->sector_size,
+		physical_block_size_sectors, max_atomic, unit_min, unit_max;
+	struct request_queue *q = sdkp->disk->queue;
+
+	if ((!sdkp->max_atomic && !sdkp->max_atomic_with_boundary) ||
+	    sdkp->protection_type == T10_PI_TYPE2_PROTECTION)
+		return;
+
+	physical_block_size_sectors = sdkp->physical_block_size /
+					sdkp->device->sector_size;
+
+	unit_min = rounddown_pow_of_two(sdkp->atomic_granularity ?
+					sdkp->atomic_granularity :
+					physical_block_size_sectors);
+
+	/*
+	 * Only use atomic boundary when we have the odd scenario of
+	 * sdkp->max_atomic == 0, which the spec does permit.
+	 */
+	if (sdkp->max_atomic) {
+		max_atomic = sdkp->max_atomic;
+		unit_max = rounddown_pow_of_two(sdkp->max_atomic);
+		sdkp->use_atomic_write_boundary = 0;
+	} else {
+		max_atomic = sdkp->max_atomic_with_boundary;
+		unit_max = rounddown_pow_of_two(sdkp->max_atomic_boundary);
+		sdkp->use_atomic_write_boundary = 1;
+	}
+
+	/*
+	 * Ensure compliance with granularity and alignment. For now, keep it
+	 * simple and just don't support atomic writes for values mismatched
+	 * with max_{boundary}atomic, physical block size, and
+	 * atomic_granularity itself.
+	 *
+	 * We're really being distrustful by checking unit_max also...
+	 */
+	if (sdkp->atomic_granularity > 1) {
+		if (unit_min > 1 && unit_min % sdkp->atomic_granularity)
+			return;
+		if (unit_max > 1 && unit_max % sdkp->atomic_granularity)
+			return;
+	}
+
+	if (sdkp->atomic_alignment > 1) {
+		if (unit_min > 1 && unit_min % sdkp->atomic_alignment)
+			return;
+		if (unit_max > 1 && unit_max % sdkp->atomic_alignment)
+			return;
+	}
+
+	blk_queue_atomic_write_max_bytes(q, max_atomic * logical_block_size);
+	blk_queue_atomic_write_unit_min_sectors(q, unit_min);
+	blk_queue_atomic_write_unit_max_sectors(q, unit_max);
+	blk_queue_atomic_write_boundary_bytes(q, 0);
+}
+
 static blk_status_t sd_setup_write_same16_cmnd(struct scsi_cmnd *cmd,
 		bool unmap)
 {
@@ -3071,7 +3130,7 @@ static void sd_read_block_limits(struct scsi_disk *sdkp)
 		sdkp->max_ws_blocks = (u32)get_unaligned_be64(&vpd->data[36]);
 
 		if (!sdkp->lbpme)
-			goto out;
+			goto read_atomics;
 
 		lba_count = get_unaligned_be32(&vpd->data[20]);
 		desc_count = get_unaligned_be32(&vpd->data[24]);
@@ -3102,6 +3161,14 @@ static void sd_read_block_limits(struct scsi_disk *sdkp)
 			else
 				sd_config_discard(sdkp, SD_LBP_DISABLE);
 		}
+read_atomics:
+		sdkp->max_atomic = get_unaligned_be32(&vpd->data[44]);
+		sdkp->atomic_alignment = get_unaligned_be32(&vpd->data[48]);
+		sdkp->atomic_granularity = get_unaligned_be32(&vpd->data[52]);
+		sdkp->max_atomic_with_boundary = get_unaligned_be32(&vpd->data[56]);
+		sdkp->max_atomic_boundary = get_unaligned_be32(&vpd->data[60]);
+
+		sd_config_atomic(sdkp);
 	}
 
  out:
diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index 409dda5350d1..990188a56b51 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -121,6 +121,13 @@ struct scsi_disk {
 	u32		max_unmap_blocks;
 	u32		unmap_granularity;
 	u32		unmap_alignment;
+
+	u32		max_atomic;
+	u32		atomic_alignment;
+	u32		atomic_granularity;
+	u32		max_atomic_with_boundary;
+	u32		max_atomic_boundary;
+
 	u32		index;
 	unsigned int	physical_block_size;
 	unsigned int	max_medium_access_timeouts;
@@ -151,6 +158,7 @@ struct scsi_disk {
 	unsigned	urswrz : 1;
 	unsigned	security : 1;
 	unsigned	ignore_medium_access_errors : 1;
+	unsigned	use_atomic_write_boundary : 1;
 };
 #define to_scsi_disk(obj) container_of(obj, struct scsi_disk, disk_dev)
 
-- 
2.31.1