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Commit 9bc142dd authored by Mike Snitzer's avatar Mike Snitzer Committed by Alasdair G Kergon
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dm thin: tidy discard support 



A little thin discard code refactoring to make the next patch (dm thin:
fix discard support for data devices) more readable.
Pull out a couple of functions (and uses bools instead of unsigned for
features).

No functional changes.

Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 3ae70656

drivers/md/dm-thin.c

+39 −25
Original line number Diff line number Diff line
@@ -509,9 +509,9 @@ enum pool_mode { 
struct pool_features {

	enum pool_mode mode;



	unsigned zero_new_blocks:1;

	unsigned discard_enabled:1;

	unsigned discard_passdown:1;

	bool zero_new_blocks:1;

	bool discard_enabled:1;

	bool discard_passdown:1;

};



struct thin_c;
@@ -1839,6 +1839,32 @@ static void __requeue_bios(struct pool *pool) 
/*----------------------------------------------------------------

 * Binding of control targets to a pool object

 *--------------------------------------------------------------*/

static bool data_dev_supports_discard(struct pool_c *pt)

{

	struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);



	return q && blk_queue_discard(q);

}



/*

 * If discard_passdown was enabled verify that the data device

 * supports discards.  Disable discard_passdown if not; otherwise

 * -EOPNOTSUPP will be returned.

 */

static void disable_passdown_if_not_supported(struct pool_c *pt,

					      struct pool_features *pf)

{

	char buf[BDEVNAME_SIZE];



	if (!pf->discard_passdown || data_dev_supports_discard(pt))

		return;



	DMWARN("Discard unsupported by data device (%s): Disabling discard passdown.",

	       bdevname(pt->data_dev->bdev, buf));



	pf->discard_passdown = false;

}



static int bind_control_target(struct pool *pool, struct dm_target *ti)

{

	struct pool_c *pt = ti->private;
@@ -1855,23 +1881,9 @@ static int bind_control_target(struct pool *pool, struct dm_target *ti) 
	pool->ti = ti;

	pool->low_water_blocks = pt->low_water_blocks;

	pool->pf = pt->pf;

	set_pool_mode(pool, new_mode);



	/*

	 * If discard_passdown was enabled verify that the data device

	 * supports discards.  Disable discard_passdown if not; otherwise

	 * -EOPNOTSUPP will be returned.

	 */

	/* FIXME: pull this out into a sep fn. */

	if (pt->pf.discard_passdown) {

		struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);

		if (!q || !blk_queue_discard(q)) {

			char buf[BDEVNAME_SIZE];

			DMWARN("Discard unsupported by data device (%s): Disabling discard passdown.",

			       bdevname(pt->data_dev->bdev, buf));

			pool->pf.discard_passdown = 0;

		}

	}

	disable_passdown_if_not_supported(pt, &pool->pf);

	set_pool_mode(pool, new_mode);



	return 0;

}
@@ -1889,9 +1901,9 @@ static void unbind_control_target(struct pool *pool, struct dm_target *ti) 
static void pool_features_init(struct pool_features *pf)

{

	pf->mode = PM_WRITE;

	pf->zero_new_blocks = 1;

	pf->discard_enabled = 1;

	pf->discard_passdown = 1;

	pf->zero_new_blocks = true;

	pf->discard_enabled = true;

	pf->discard_passdown = true;

}



static void __pool_destroy(struct pool *pool)
@@ -2119,13 +2131,13 @@ static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf, 
		argc--;



		if (!strcasecmp(arg_name, "skip_block_zeroing"))

			pf->zero_new_blocks = 0;

			pf->zero_new_blocks = false;



		else if (!strcasecmp(arg_name, "ignore_discard"))

			pf->discard_enabled = 0;

			pf->discard_enabled = false;



		else if (!strcasecmp(arg_name, "no_discard_passdown"))

			pf->discard_passdown = 0;

			pf->discard_passdown = false;



		else if (!strcasecmp(arg_name, "read_only"))

			pf->mode = PM_READ_ONLY;
@@ -2261,6 +2273,7 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv) 
	pt->low_water_blocks = low_water_blocks;

	pt->pf = pf;

	ti->num_flush_requests = 1;



	/*

	 * Only need to enable discards if the pool should pass

	 * them down to the data device.  The thin device's discard
@@ -2268,6 +2281,7 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv) 
	 */

	if (pf.discard_enabled && pf.discard_passdown) {

		ti->num_discard_requests = 1;



		/*

		 * Setting 'discards_supported' circumvents the normal

		 * stacking of discard limits (this keeps the pool and