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Commit 7e64db15 authored by Jan Höppner's avatar Jan Höppner Committed by Vasily Gorbik
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s390/dasd: Add discard support for ESE volumes 



ESE (Extent Space Efficient) volumes are thin-provisioned and therefore
space is only occupied with real data. In order to make previously used
space available for re-allocation again, discard support is enabled for
ESE volumes allowing the DASD driver to release said space.

Signed-off-by: default avatarJan Höppner <hoeppner@linux.ibm.com>
Reviewed-by: default avatarStefan Haberland <sth@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent b5444153

drivers/s390/block/dasd_eckd.c

+54 −3
Original line number Diff line number Diff line
@@ -1987,6 +1987,9 @@ dasd_eckd_check_characteristics(struct dasd_device *device) 
	if (readonly)

		set_bit(DASD_FLAG_DEVICE_RO, &device->flags);



	if (dasd_eckd_is_ese(device))

		dasd_set_feature(device->cdev, DASD_FEATURE_DISCARD, 1);



	dev_info(&device->cdev->dev, "New DASD %04X/%02X (CU %04X/%02X) "

		 "with %d cylinders, %d heads, %d sectors%s\n",

		 private->rdc_data.dev_type,
@@ -3617,6 +3620,14 @@ static int dasd_eckd_release_space(struct dasd_device *device, 
		return -EINVAL;

}



static struct dasd_ccw_req *

dasd_eckd_build_cp_discard(struct dasd_device *device, struct dasd_block *block,

			   struct request *req, sector_t first_trk,

			   sector_t last_trk)

{

	return dasd_eckd_dso_ras(device, block, req, first_trk, last_trk, 1);

}



static struct dasd_ccw_req *dasd_eckd_build_cp_cmd_single(

					       struct dasd_device *startdev,

					       struct dasd_block *block,
@@ -4361,6 +4372,10 @@ static struct dasd_ccw_req *dasd_eckd_build_cp(struct dasd_device *startdev, 
	cmdwtd = private->features.feature[12] & 0x40;

	use_prefix = private->features.feature[8] & 0x01;



	if (req_op(req) == REQ_OP_DISCARD)

		return dasd_eckd_build_cp_discard(startdev, block, req,

						  first_trk, last_trk);



	cqr = NULL;

	if (cdlspecial || dasd_page_cache) {

		/* do nothing, just fall through to the cmd mode single case */
@@ -4639,11 +4654,13 @@ static struct dasd_ccw_req *dasd_eckd_build_alias_cp(struct dasd_device *base, 
						     struct dasd_block *block,

						     struct request *req)

{

	struct dasd_device *startdev = NULL;

	struct dasd_eckd_private *private;

	struct dasd_device *startdev;

	unsigned long flags;

	struct dasd_ccw_req *cqr;

	unsigned long flags;



	/* Discard requests can only be processed on base devices */

	if (req_op(req) != REQ_OP_DISCARD)

		startdev = dasd_alias_get_start_dev(base);

	if (!startdev)

		startdev = base;
@@ -6357,8 +6374,20 @@ static void dasd_eckd_setup_blk_queue(struct dasd_block *block) 
	unsigned int logical_block_size = block->bp_block;

	struct request_queue *q = block->request_queue;

	struct dasd_device *device = block->base;

	struct dasd_eckd_private *private;

	unsigned int max_discard_sectors;

	unsigned int max_bytes;

	unsigned int ext_bytes; /* Extent Size in Bytes */

	int recs_per_trk;

	int trks_per_cyl;

	int ext_limit;

	int ext_size; /* Extent Size in Cylinders */

	int max;



	private = device->private;

	trks_per_cyl = private->rdc_data.trk_per_cyl;

	recs_per_trk = recs_per_track(&private->rdc_data, 0, logical_block_size);



	if (device->features & DASD_FEATURE_USERAW) {

		/*

		 * the max_blocks value for raw_track access is 256
@@ -6379,6 +6408,28 @@ static void dasd_eckd_setup_blk_queue(struct dasd_block *block) 
	/* With page sized segments each segment can be translated into one idaw/tidaw */

	blk_queue_max_segment_size(q, PAGE_SIZE);

	blk_queue_segment_boundary(q, PAGE_SIZE - 1);



	if (dasd_eckd_is_ese(device)) {

		/*

		 * Depending on the extent size, up to UINT_MAX bytes can be

		 * accepted. However, neither DASD_ECKD_RAS_EXTS_MAX nor the

		 * device limits should be exceeded.

		 */

		ext_size = dasd_eckd_ext_size(device);

		ext_limit = min(private->real_cyl / ext_size, DASD_ECKD_RAS_EXTS_MAX);

		ext_bytes = ext_size * trks_per_cyl * recs_per_trk *

			logical_block_size;

		max_bytes = UINT_MAX - (UINT_MAX % ext_bytes);

		if (max_bytes / ext_bytes > ext_limit)

			max_bytes = ext_bytes * ext_limit;



		max_discard_sectors = max_bytes / 512;



		blk_queue_max_discard_sectors(q, max_discard_sectors);

		blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);

		q->limits.discard_granularity = ext_bytes;

		q->limits.discard_alignment = ext_bytes;

	}

}



static struct ccw_driver dasd_eckd_driver = {