s390/tape: Remove special block id handling

For real 3490 tape models a logical block was composed of a direction
bit (wrap), a segment number, a format mode, and a logical block number.
This is represented in a 4byte identifier.

The Virtual Tape Server (VTS) emulates 3490 tape devices and uses a
stripped block id format where bit 0-9 of the 4byte identifier are
always 0. Bit 10-31 represent the logical block number.

All tapes use the 3480-2 XF format, which was defined via
TAPE34XX_FMT_3480_2_XF but never used. There is also no special handling
required anymore as this is the only format being used.

Since VTS doesn't require any special handling of block ids and format,
corresponding code is removed.

Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Author: hoeppnerj

drivers/s390/char/tape.h

@@ -186,7 +186,6 @@ struct tape_device {
 
 	/* Device discipline information. */
 	struct tape_discipline *	discipline;
-	void *				discdata;
 
 	/* Generic status flags */
 	long				tape_generic_status;

drivers/s390/char/tape_34xx.c

@@ -28,27 +28,11 @@
 debug_info_t *TAPE_DBF_AREA = NULL;
 EXPORT_SYMBOL(TAPE_DBF_AREA);
 
-#define TAPE34XX_FMT_3480	0
-#define TAPE34XX_FMT_3480_2_XF	1
-#define TAPE34XX_FMT_3480_XF	2
-
 struct tape_34xx_block_id {
-	unsigned int	wrap		: 1;
-	unsigned int	segment		: 7;
-	unsigned int	format		: 2;
+	unsigned int	unused		: 10;
 	unsigned int	block		: 22;
 };
 
-/*
- * A list of block ID's is used to faster seek blocks.
- */
-struct tape_34xx_sbid {
-	struct list_head		list;
-	struct tape_34xx_block_id	bid;
-};
-
-static void tape_34xx_delete_sbid_from(struct tape_device *, int);
-
 /*
  * Medium sense for 34xx tapes. There is no 'real' medium sense call.
  * So we just do a normal sense.
@@ -175,19 +159,6 @@ static inline int
 tape_34xx_done(struct tape_request *request)
 {
 	DBF_EVENT(6, "%s done\n", tape_op_verbose[request->op]);
-
-	switch (request->op) {
-		case TO_DSE:
-		case TO_RUN:
-		case TO_WRI:
-		case TO_WTM:
-		case TO_ASSIGN:
-		case TO_UNASSIGN:
-			tape_34xx_delete_sbid_from(request->device, 0);
-			break;
-		default:
-			;
-	}
 	return TAPE_IO_SUCCESS;
 }
 
@@ -224,7 +195,6 @@ tape_34xx_unsolicited_irq(struct tape_device *device, struct irb *irb)
 	if (irb->scsw.cmd.dstat == 0x85) { /* READY */
 		/* A medium was inserted in the drive. */
 		DBF_EVENT(6, "xuud med\n");
-		tape_34xx_delete_sbid_from(device, 0);
 		tape_34xx_schedule_work(device, TO_MSEN);
 	} else {
 		DBF_EVENT(3, "unsol.irq! dev end: %08x\n", device->cdev_id);
@@ -356,7 +326,6 @@ tape_34xx_unit_check(struct tape_device *device, struct tape_request *request,
 		 */
 		case TO_LBL:
 			/* Block could not be located. */
-			tape_34xx_delete_sbid_from(device, 0);
 			return tape_34xx_erp_failed(request, -EIO);
 
 		case TO_RFO:
@@ -543,7 +512,6 @@ tape_34xx_unit_check(struct tape_device *device, struct tape_request *request,
 		 */
 		dev_warn (&device->cdev->dev, "The tape unit failed to load"
 			" the cartridge\n");
-		tape_34xx_delete_sbid_from(device, 0);
 		return tape_34xx_erp_failed(request, -EIO);
 	case 0x34:
 		/*
@@ -601,7 +569,6 @@ tape_34xx_unit_check(struct tape_device *device, struct tape_request *request,
 		/* Manual rewind or unload. This causes an I/O error. */
 		dev_warn (&device->cdev->dev, "The tape medium has been "
 			"rewound or unloaded manually\n");
-		tape_34xx_delete_sbid_from(device, 0);
 		return tape_34xx_erp_failed(request, -EIO);
 	case 0x42:
 		/*
@@ -613,7 +580,6 @@ tape_34xx_unit_check(struct tape_device *device, struct tape_request *request,
 		return tape_34xx_erp_retry(request);
 	case 0x43:
 		/* Drive not ready. */
-		tape_34xx_delete_sbid_from(device, 0);
 		tape_med_state_set(device, MS_UNLOADED);
 		/* Some commands commands are successful even in this case */
 		if (sense[1] & SENSE_DRIVE_ONLINE) {
@@ -653,7 +619,6 @@ tape_34xx_unit_check(struct tape_device *device, struct tape_request *request,
 		/* Volume fenced. CU reports volume integrity is lost. */
 		dev_warn (&device->cdev->dev, "The control unit has fenced "
 			"access to the tape volume\n");
-		tape_34xx_delete_sbid_from(device, 0);
 		return tape_34xx_erp_failed(request, -EIO);
 	case 0x48:
 		/* Log sense data and retry request. */
@@ -725,7 +690,6 @@ tape_34xx_unit_check(struct tape_device *device, struct tape_request *request,
 		/* End of Volume complete. Rewind unload completed ok. */
 		if (request->op == TO_RUN) {
 			tape_med_state_set(device, MS_UNLOADED);
-			tape_34xx_delete_sbid_from(device, 0);
 			return tape_34xx_erp_succeeded(request);
 		}
 		return tape_34xx_erp_bug(device, request, irb, sense[3]);
@@ -835,183 +799,24 @@ tape_34xx_irq(struct tape_device *device, struct tape_request *request,
 	return TAPE_IO_STOP;
 }
 
-static inline void
-tape_34xx_append_new_sbid(struct tape_34xx_block_id bid, struct list_head *l)
-{
-	struct tape_34xx_sbid *	new_sbid;
-
-	new_sbid = kmalloc(sizeof(*new_sbid), GFP_ATOMIC);
-	if (!new_sbid)
-		return;
-
-	new_sbid->bid = bid;
-	list_add(&new_sbid->list, l);
-}
-
-/*
- * Build up the search block ID list. The block ID consists of a logical
- * block number and a hardware specific part. The hardware specific part
- * helps the tape drive to speed up searching for a specific block.
- */
-static void
-tape_34xx_add_sbid(struct tape_device *device, struct tape_34xx_block_id bid)
-{
-	struct list_head *	sbid_list;
-	struct tape_34xx_sbid *	sbid;
-	struct list_head *	l;
-
-	/*
-	 * immediately return if there is no list at all or the block to add
-	 * is located in segment 1 of wrap 0 because this position is used
-	 * if no hardware position data is supplied.
-	 */
-	sbid_list = (struct list_head *) device->discdata;
-	if (!sbid_list || (bid.segment < 2 && bid.wrap == 0))
-		return;
-
-	/*
-	 * Search the position where to insert the new entry. Hardware
-	 * acceleration uses only the segment and wrap number. So we
-	 * need only one entry for a specific wrap/segment combination.
-	 * If there is a block with a lower number but the same hard-
-	 * ware position data we just update the block number in the
-	 * existing entry.
-	 */
-	list_for_each(l, sbid_list) {
-		sbid = list_entry(l, struct tape_34xx_sbid, list);
-
-		if (
-			(sbid->bid.segment == bid.segment) &&
-			(sbid->bid.wrap    == bid.wrap)
-		) {
-			if (bid.block < sbid->bid.block)
-				sbid->bid = bid;
-			else return;
-			break;
-		}
-
-		/* Sort in according to logical block number. */
-		if (bid.block < sbid->bid.block) {
-			tape_34xx_append_new_sbid(bid, l->prev);
-			break;
-		}
-	}
-	/* List empty or new block bigger than last entry. */
-	if (l == sbid_list)
-		tape_34xx_append_new_sbid(bid, l->prev);
-
-	DBF_LH(4, "Current list is:\n");
-	list_for_each(l, sbid_list) {
-		sbid = list_entry(l, struct tape_34xx_sbid, list);
-		DBF_LH(4, "%d:%03d@%05d\n",
-			sbid->bid.wrap,
-			sbid->bid.segment,
-			sbid->bid.block
-		);
-	}
-}
-
-/*
- * Delete all entries from the search block ID list that belong to tape blocks
- * equal or higher than the given number.
- */
-static void
-tape_34xx_delete_sbid_from(struct tape_device *device, int from)
-{
-	struct list_head *	sbid_list;
-	struct tape_34xx_sbid *	sbid;
-	struct list_head *	l;
-	struct list_head *	n;
-
-	sbid_list = (struct list_head *) device->discdata;
-	if (!sbid_list)
-		return;
-
-	list_for_each_safe(l, n, sbid_list) {
-		sbid = list_entry(l, struct tape_34xx_sbid, list);
-		if (sbid->bid.block >= from) {
-			DBF_LH(4, "Delete sbid %d:%03d@%05d\n",
-				sbid->bid.wrap,
-				sbid->bid.segment,
-				sbid->bid.block
-			);
-			list_del(l);
-			kfree(sbid);
-		}
-	}
-}
-
-/*
- * Merge hardware position data into a block id.
- */
-static void
-tape_34xx_merge_sbid(
-	struct tape_device *		device,
-	struct tape_34xx_block_id *	bid
-) {
-	struct tape_34xx_sbid *	sbid;
-	struct tape_34xx_sbid *	sbid_to_use;
-	struct list_head *	sbid_list;
-	struct list_head *	l;
-
-	sbid_list = (struct list_head *) device->discdata;
-	bid->wrap    = 0;
-	bid->segment = 1;
-
-	if (!sbid_list || list_empty(sbid_list))
-		return;
-
-	sbid_to_use = NULL;
-	list_for_each(l, sbid_list) {
-		sbid = list_entry(l, struct tape_34xx_sbid, list);
-
-		if (sbid->bid.block >= bid->block)
-			break;
-		sbid_to_use = sbid;
-	}
-	if (sbid_to_use) {
-		bid->wrap    = sbid_to_use->bid.wrap;
-		bid->segment = sbid_to_use->bid.segment;
-		DBF_LH(4, "Use %d:%03d@%05d for %05d\n",
-			sbid_to_use->bid.wrap,
-			sbid_to_use->bid.segment,
-			sbid_to_use->bid.block,
-			bid->block
-		);
-	}
-}
-
 static int
 tape_34xx_setup_device(struct tape_device * device)
 {
-	int			rc;
-	struct list_head *	discdata;
+	int rc;
 
 	DBF_EVENT(6, "34xx device setup\n");
 	if ((rc = tape_std_assign(device)) == 0) {
 		if ((rc = tape_34xx_medium_sense(device)) != 0) {
 			DBF_LH(3, "34xx medium sense returned %d\n", rc);
 		}
 	}
-	discdata = kmalloc(sizeof(struct list_head), GFP_KERNEL);
-	if (discdata) {
-			INIT_LIST_HEAD(discdata);
-			device->discdata = discdata;
-	}
-
 	return rc;
 }
 
 static void
 tape_34xx_cleanup_device(struct tape_device *device)
 {
 	tape_std_unassign(device);
-	
-	if (device->discdata) {
-		tape_34xx_delete_sbid_from(device, 0);
-		kfree(device->discdata);
-		device->discdata = NULL;
-	}
 }
 
 
@@ -1031,7 +836,6 @@ tape_34xx_mttell(struct tape_device *device, int mt_count)
 	if (rc)
 		return rc;
 
-	tape_34xx_add_sbid(device, block_id.cbid);
 	return block_id.cbid.block;
 }
 
@@ -1055,10 +859,7 @@ tape_34xx_mtseek(struct tape_device *device, int mt_count)
 	/* setup ccws */
 	request->op = TO_LBL;
 	bid         = (struct tape_34xx_block_id *) request->cpdata;
-	bid->format = (*device->modeset_byte & 0x08) ?
-			TAPE34XX_FMT_3480_XF : TAPE34XX_FMT_3480;
 	bid->block  = mt_count;
-	tape_34xx_merge_sbid(device, bid);
 
 	tape_ccw_cc(request->cpaddr, MODE_SET_DB, 1, device->modeset_byte);
 	tape_ccw_cc(request->cpaddr + 1, LOCATE, 4, request->cpdata);