From: Damien Le Moal <redacted>

Introduce the command duration limits helper function
sd_cdl_cmd_limit() to retrieve and set the DLD bits of the
READ/WRITE 16 and READ/WRITE 32 commands to indicate to the device
the command duration limit descriptor to apply to the command.

When command duration limits are enabled, sd_cdl_cmd_limit() obtains the
index of the descriptor to apply to the command for requests that have
the IOPRIO_CLASS_DL priority class with a priority data sepcifying a
valid descriptor index (1 to 7).

The read-write sysfs attribute "enable" is introduced to control
setting the command duration limits indexes. If this attribute is set
to 0 (default), command duration limits specified by the user are
ignored. The user must set this attribute to 1 for command duration
limits to be set. Enabling and disabling the command duration limits
feature for ATA devices must be done using the ATA feature sub-page of
the control mode page. The sd_cdl_enable() function is introduced to
check if this mode page is supported by the device and if it is, use
it to enable/disable CDL.

Signed-off-by: Damien Le Moal <redacted>
Co-developed-by: Niklas Cassel <redacted>
Signed-off-by: Niklas Cassel <redacted>
---
  drivers/scsi/sd.c     |  16 +++--
  drivers/scsi/sd.h     |  10 ++++
  drivers/scsi/sd_cdl.c | 134 +++++++++++++++++++++++++++++++++++++++++-
  3 files changed, 152 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 7879a5470773..d2eb01337943 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c

@@ -1045,13 +1045,14 @@ static blk_status_t sd_setup_flush_cmnd(struct scsi_cmnd *cmd)
  
  static blk_status_t sd_setup_rw32_cmnd(struct scsi_cmnd *cmd, bool write,
  				       sector_t lba, unsigned int nr_blocks,
-				       unsigned char flags)
+				       unsigned char flags, unsigned int dld)
  {
  	cmd->cmd_len = SD_EXT_CDB_SIZE;
  	cmd->cmnd[0]  = VARIABLE_LENGTH_CMD;
  	cmd->cmnd[7]  = 0x18; /* Additional CDB len */
  	cmd->cmnd[9]  = write ? WRITE_32 : READ_32;
  	cmd->cmnd[10] = flags;
+	cmd->cmnd[11] = dld & 0x07;
  	put_unaligned_be64(lba, &cmd->cmnd[12]);
  	put_unaligned_be32(lba, &cmd->cmnd[20]); /* Expected Indirect LBA */
  	put_unaligned_be32(nr_blocks, &cmd->cmnd[28]);

@@ -1061,12 +1062,12 @@ static blk_status_t sd_setup_rw32_cmnd(struct scsi_cmnd *cmd, bool write,
  
  static blk_status_t sd_setup_rw16_cmnd(struct scsi_cmnd *cmd, bool write,
  				       sector_t lba, unsigned int nr_blocks,
-				       unsigned char flags)
+				       unsigned char flags, unsigned int dld)
  {
  	cmd->cmd_len  = 16;
  	cmd->cmnd[0]  = write ? WRITE_16 : READ_16;
-	cmd->cmnd[1]  = flags;
-	cmd->cmnd[14] = 0;
+	cmd->cmnd[1]  = flags | ((dld >> 2) & 0x01);
+	cmd->cmnd[14] = (dld & 0x03) << 6;
  	cmd->cmnd[15] = 0;
  	put_unaligned_be64(lba, &cmd->cmnd[2]);
  	put_unaligned_be32(nr_blocks, &cmd->cmnd[10]);

@@ -1129,6 +1130,7 @@ static blk_status_t sd_setup_read_write_cmnd(struct scsi_cmnd *cmd)
  	unsigned int mask = logical_to_sectors(sdp, 1) - 1;
  	bool write = rq_data_dir(rq) == WRITE;
  	unsigned char protect, fua;
+	unsigned int dld = 0;
  	blk_status_t ret;
  	unsigned int dif;
  	bool dix;

@@ -1178,6 +1180,8 @@ static blk_status_t sd_setup_read_write_cmnd(struct scsi_cmnd *cmd)
  	fua = rq->cmd_flags & REQ_FUA ? 0x8 : 0;
  	dix = scsi_prot_sg_count(cmd);
  	dif = scsi_host_dif_capable(cmd->device->host, sdkp->protection_type);
+	if (sd_cdl_enabled(sdkp))
+		dld = sd_cdl_dld(sdkp, cmd);
  
  	if (dif || dix)
  		protect = sd_setup_protect_cmnd(cmd, dix, dif);

@@ -1186,10 +1190,10 @@ static blk_status_t sd_setup_read_write_cmnd(struct scsi_cmnd *cmd)
  
  	if (protect && sdkp->protection_type == T10_PI_TYPE2_PROTECTION) {
  		ret = sd_setup_rw32_cmnd(cmd, write, lba, nr_blocks,
-					 protect | fua);
+					 protect | fua, dld);
  	} else if (sdp->use_16_for_rw || (nr_blocks > 0xffff)) {
  		ret = sd_setup_rw16_cmnd(cmd, write, lba, nr_blocks,
-					 protect | fua);
+					 protect | fua, dld);
  	} else if ((nr_blocks > 0xff) || (lba > 0x1fffff) ||
  		   sdp->use_10_for_rw || protect) {
  		ret = sd_setup_rw10_cmnd(cmd, write, lba, nr_blocks,

diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index e60d33bd222a..5b6b6dc4b92d 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h

@@ -130,8 +130,11 @@ struct sd_cdl_page {
  	struct sd_cdl_desc      descs[SD_CDL_MAX_DESC];
  };
  
+struct scsi_disk;
+
  struct sd_cdl {
  	struct kobject		kobj;
+	struct scsi_disk	*sdkp;
  	bool			sysfs_registered;
  	u8			perf_vs_duration_guideline;
  	struct sd_cdl_page	pages[SD_CDL_RW];

@@ -188,6 +191,7 @@ struct scsi_disk {
  	u8		zeroing_mode;
  	u8		nr_actuators;		/* Number of actuators */
  	struct sd_cdl	*cdl;
+	unsigned	cdl_enabled : 1;
  	unsigned	ATO : 1;	/* state of disk ATO bit */
  	unsigned	cache_override : 1; /* temp override of WCE,RCD */
  	unsigned	WCE : 1;	/* state of disk WCE bit */

@@ -355,5 +359,11 @@ void sd_print_result(const struct scsi_disk *sdkp, const char *msg, int result);
  /* Command duration limits support (in sd_cdl.c) */
  void sd_read_cdl(struct scsi_disk *sdkp, unsigned char *buf);
  void sd_cdl_release(struct scsi_disk *sdkp);
+int sd_cdl_dld(struct scsi_disk *sdkp, struct scsi_cmnd *scmd);
+
+static inline bool sd_cdl_enabled(struct scsi_disk *sdkp)
+{
+	return sdkp->cdl && sdkp->cdl_enabled;
+}
  
  #endif /* _SCSI_DISK_H */

diff --git a/drivers/scsi/sd_cdl.c b/drivers/scsi/sd_cdl.c
index 513cd989f19a..59d02dbb5ea1 100644
--- a/drivers/scsi/sd_cdl.c
+++ b/drivers/scsi/sd_cdl.c

@@ -93,6 +93,63 @@ static const char *sd_cdl_policy_name(u8 policy)
  	}
  }
  
+/*
+ * Enable/disable CDL.
+ */
+static int sd_cdl_enable(struct scsi_disk *sdkp, bool enable)
+{
+	struct scsi_device *sdp = sdkp->device;
+	struct scsi_mode_data data;
+	struct scsi_sense_hdr sshdr;
+	struct scsi_vpd *vpd;
+	bool is_ata = false;
+	char buf[64];
+	int ret;
+
+	rcu_read_lock();
+	vpd = rcu_dereference(sdp->vpd_pg89);
+	if (vpd)
+		is_ata = true;
+	rcu_read_unlock();
+
+	/*
+	 * For ATA devices, CDL needs to be enabled with a SET FEATURES command.
+	 */
+	if (is_ata) {
+		char *buf_data;
+		int len;
+
+		ret = scsi_mode_sense(sdp, 0x08, 0x0a, 0xf2, buf, sizeof(buf),
+				      SD_TIMEOUT, sdkp->max_retries, &data,
+				      NULL);
+		if (ret)
+			return -EINVAL;
+