scsi: scsi_debug: First fixes for tapes

Patch includes the following:

 - Enable MODE SENSE/SELECT without actual page (to read/write only the
   Block Descriptor)

 - Store the density code and block size in the Block Descriptor (only
   short version for tapes)

 - Fix REWIND not to use the wrong page filling function

Signed-off-by: Kai Mäkisara <Kai.Makisara@kolumbus.fi>
Link: https://lore.kernel.org/r/20250213092636.2510-2-Kai.Makisara@kolumbus.fi
Reviewed-by: John Meneghini <jmeneghi@redhat.com>
Tested-by: John Meneghini <jmeneghi@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 49 insertions, 6 deletions

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 5ceaa4665e5d..4da0c259390b 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -173,6 +173,10 @@ static const char *sdebug_version_date = "20210520";
 #define DEF_ZBC_MAX_OPEN_ZONES	8
 #define DEF_ZBC_NR_CONV_ZONES	1
 
+/* Default parameters for tape drives */
+#define TAPE_DEF_DENSITY  0x0
+#define TAPE_DEF_BLKSIZE  0
+
 #define SDEBUG_LUN_0_VAL 0
 
 /* bit mask values for sdebug_opts */
@@ -363,6 +367,10 @@ struct sdebug_dev_info {
 	ktime_t create_ts;	/* time since bootup that this device was created */
 	struct sdeb_zone_state *zstate;
 
+	/* For tapes */
+	unsigned int tape_blksize;
+	unsigned int tape_density;
+
 	struct dentry *debugfs_entry;
 	struct spinlock list_lock;
 	struct list_head inject_err_list;
@@ -773,7 +781,7 @@ static const struct opcode_info_t opcode_info_arr[SDEB_I_LAST_ELEM_P1 + 1] = {
 /* 20 */
 	{0, 0x1e, 0, 0, NULL, NULL, /* ALLOW REMOVAL */
 	    {6,  0, 0, 0, 0x3, 0xc7, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} },
-	{0, 0x1, 0, 0, resp_start_stop, NULL, /* REWIND ?? */
+	{0, 0x1, 0, 0, NULL, NULL, /* REWIND ?? */
 	    {6,  0x1, 0, 0, 0, 0xc7, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} },
 	{0, 0, 0, F_INV_OP | FF_RESPOND, NULL, NULL, /* ATA_PT */
 	    {0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} },
@@ -2742,7 +2750,7 @@ static int resp_mode_sense(struct scsi_cmnd *scp,
 	unsigned char *ap;
 	unsigned char *arr __free(kfree);
 	unsigned char *cmd = scp->cmnd;
-	bool dbd, llbaa, msense_6, is_disk, is_zbc;
+	bool dbd, llbaa, msense_6, is_disk, is_zbc, is_tape;
 
 	arr = kzalloc(SDEBUG_MAX_MSENSE_SZ, GFP_ATOMIC);
 	if (!arr)
@@ -2755,7 +2763,8 @@ static int resp_mode_sense(struct scsi_cmnd *scp,
 	llbaa = msense_6 ? false : !!(cmd[1] & 0x10);
 	is_disk = (sdebug_ptype == TYPE_DISK);
 	is_zbc = devip->zoned;
-	if ((is_disk || is_zbc) && !dbd)
+	is_tape = (sdebug_ptype == TYPE_TAPE);
+	if ((is_disk || is_zbc || is_tape) && !dbd)
 		bd_len = llbaa ? 16 : 8;
 	else
 		bd_len = 0;
@@ -2793,15 +2802,25 @@ static int resp_mode_sense(struct scsi_cmnd *scp,
 			put_unaligned_be32(0xffffffff, ap + 0);
 		else
 			put_unaligned_be32(sdebug_capacity, ap + 0);
-		put_unaligned_be16(sdebug_sector_size, ap + 6);
+		if (is_tape) {
+			ap[0] = devip->tape_density;
+			put_unaligned_be16(devip->tape_blksize, ap + 6);
+		} else
+			put_unaligned_be16(sdebug_sector_size, ap + 6);
 		offset += bd_len;
 		ap = arr + offset;
 	} else if (16 == bd_len) {
+		if (is_tape) {
+			mk_sense_invalid_fld(scp, SDEB_IN_DATA, 1, 4);
+			return check_condition_result;
+		}
 		put_unaligned_be64((u64)sdebug_capacity, ap + 0);
 		put_unaligned_be32(sdebug_sector_size, ap + 12);
 		offset += bd_len;
 		ap = arr + offset;
 	}
+	if (cmd[2] == 0)
+		goto only_bd; /* Only block descriptor requested */
 
 	/*
 	 * N.B. If len>0 before resp_*_pg() call, then form of that call should be:
@@ -2902,6 +2921,7 @@ static int resp_mode_sense(struct scsi_cmnd *scp,
 	default:
 		goto bad_pcode;
 	}
+only_bd:
 	if (msense_6)
 		arr[0] = offset - 1;
 	else
@@ -2945,8 +2965,27 @@ static int resp_mode_select(struct scsi_cmnd *scp,
 			    __func__, param_len, res);
 	md_len = mselect6 ? (arr[0] + 1) : (get_unaligned_be16(arr + 0) + 2);
 	bd_len = mselect6 ? arr[3] : get_unaligned_be16(arr + 6);
-	off = bd_len + (mselect6 ? 4 : 8);
-	if (md_len > 2 || off >= res) {
+	off = (mselect6 ? 4 : 8);
+	if (sdebug_ptype == TYPE_TAPE) {
+		int blksize;
+
+		if (bd_len != 8) {
+			mk_sense_invalid_fld(scp, SDEB_IN_DATA,
+					mselect6 ? 3 : 6, -1);
+			return check_condition_result;
+		}
+		blksize = get_unaligned_be16(arr + off + 6);
+		if ((blksize % 4) != 0) {
+			mk_sense_invalid_fld(scp, SDEB_IN_DATA, off + 6, -1);
+			return check_condition_result;
+		}
+		devip->tape_density = arr[off];
+		devip->tape_blksize = blksize;
+	}
+	off += bd_len;
+	if (off >= res)
+		return 0; /* No page written, just descriptors */
+	if (md_len > 2) {
 		mk_sense_invalid_fld(scp, SDEB_IN_DATA, 0, -1);
 		return check_condition_result;
 	}
@@ -5835,6 +5874,10 @@ static struct sdebug_dev_info *sdebug_device_create(
 		} else {
 			devip->zoned = false;
 		}
+		if (sdebug_ptype == TYPE_TAPE) {
+			devip->tape_density = TAPE_DEF_DENSITY;
+			devip->tape_blksize = TAPE_DEF_BLKSIZE;
+		}
 		devip->create_ts = ktime_get_boottime();
 		atomic_set(&devip->stopped, (sdeb_tur_ms_to_ready > 0 ? 2 : 0));
 		spin_lock_init(&devip->list_lock);