[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

[dm-devel] [PATCH 12/13] dm thin: add discard pool features



From: Joe Thornber <ejt redhat com>

Make additional features available during pool creation:

 'skip_discard': disable discard support
 'skip_discard_passdown': don't pass discards down to the underlying data device

Signed-off-by: Joe Thornber <ejt redhat com>
Acked-by: Mike Snitzer <snitzer redhat com>
---
 Documentation/device-mapper/thin-provisioning.txt |    2 +
 drivers/md/dm-thin.c                              |   79 +++++++++++++++------
 2 files changed, 59 insertions(+), 22 deletions(-)

diff --git a/Documentation/device-mapper/thin-provisioning.txt b/Documentation/device-mapper/thin-provisioning.txt
index 13e42fb..57076dd 100644
--- a/Documentation/device-mapper/thin-provisioning.txt
+++ b/Documentation/device-mapper/thin-provisioning.txt
@@ -222,6 +222,8 @@ i) Constructor
 
     Optional feature arguments:
     - 'skip_block_zeroing': skips the zeroing of newly-provisioned blocks.
+      'skip_discard': disable discard support
+      'skip_discard_passdown': don't pass discards down to the underlying data device
 
     Data block size must be between 64KB (128 sectors) and 1GB
     (2097152 sectors) inclusive.
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index fec7ddb..2e16b3a 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -500,6 +500,13 @@ static void build_virtual_key(struct dm_thin_device *td, dm_block_t b,
  * devices.
  */
 struct new_mapping;
+
+struct pool_features {
+	unsigned zero_new_blocks:1;
+	unsigned discard_enabled:1;
+	unsigned discard_passdown:1;
+};
+
 struct pool {
 	struct list_head list;
 	struct dm_target *ti;	/* Only set if a pool target is bound */
@@ -513,7 +520,7 @@ struct pool {
 	dm_block_t offset_mask;
 	dm_block_t low_water_blocks;
 
-	unsigned zero_new_blocks:1;
+	struct pool_features pf;
 	unsigned low_water_triggered:1;	/* A dm event has been sent */
 	unsigned no_free_space:1;	/* A -ENOSPC warning has been issued */
 
@@ -554,7 +561,7 @@ struct pool_c {
 	struct dm_target_callbacks callbacks;
 
 	dm_block_t low_water_blocks;
-	unsigned zero_new_blocks:1;
+	struct pool_features pf;
 };
 
 /*
@@ -1060,7 +1067,7 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
 	 * zeroing pre-existing data, we can issue the bio immediately.
 	 * Otherwise we use kcopyd to zero the data first.
 	 */
-	if (!pool->zero_new_blocks)
+	if (!pool->pf.zero_new_blocks)
 		process_prepared_mapping(m);
 
 	else if (io_overwrites_block(pool, bio)) {
@@ -1626,7 +1633,7 @@ static int bind_control_target(struct pool *pool, struct dm_target *ti)
 
 	pool->ti = ti;
 	pool->low_water_blocks = pt->low_water_blocks;
-	pool->zero_new_blocks = pt->zero_new_blocks;
+	pool->pf = pt->pf;
 
 	return 0;
 }
@@ -1640,6 +1647,14 @@ static void unbind_control_target(struct pool *pool, struct dm_target *ti)
 /*----------------------------------------------------------------
  * Pool creation
  *--------------------------------------------------------------*/
+/* Initialize pool features. */
+static void pool_features_init(struct pool_features *pf)
+{
+	pf->zero_new_blocks = 1;
+	pf->discard_enabled = 1;
+	pf->discard_passdown = 1;
+}
+
 static void __pool_destroy(struct pool *pool)
 {
 	__pool_table_remove(pool);
@@ -1687,7 +1702,7 @@ static struct pool *pool_create(struct mapped_device *pool_md,
 	pool->block_shift = ffs(block_size) - 1;
 	pool->offset_mask = block_size - 1;
 	pool->low_water_blocks = 0;
-	pool->zero_new_blocks = 1;
+	pool_features_init(&pool->pf);
 	pool->prison = prison_create(PRISON_CELLS);
 	if (!pool->prison) {
 		*error = "Error creating pool's bio prison";
@@ -1825,10 +1840,6 @@ static void pool_dtr(struct dm_target *ti)
 	mutex_unlock(&dm_thin_pool_table.mutex);
 }
 
-struct pool_features {
-	unsigned zero_new_blocks:1;
-};
-
 static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf,
 			       struct dm_target *ti)
 {
@@ -1837,7 +1848,7 @@ static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf,
 	const char *arg_name;
 
 	static struct dm_arg _args[] = {
-		{0, 1, "Invalid number of pool feature arguments"},
+		{0, 3, "Invalid number of pool feature arguments"},
 	};
 
 	/*
@@ -1857,6 +1868,12 @@ static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf,
 		if (!strcasecmp(arg_name, "skip_block_zeroing")) {
 			pf->zero_new_blocks = 0;
 			continue;
+		} else if (!strcasecmp(arg_name, "skip_discard")) {
+			pf->discard_enabled = 0;
+			continue;
+		} else if (!strcasecmp(arg_name, "skip_discard_passdown")) {
+			pf->discard_passdown = 0;
+			continue;
 		}
 
 		ti->error = "Unrecognised pool feature requested";
@@ -1874,6 +1891,8 @@ static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf,
  *
  * Optional feature arguments are:
  *	     skip_block_zeroing: skips the zeroing of newly-provisioned blocks.
+ *           skip_discard: disable discard
+ *           skip_discard_passdown: don't pass discards down to the data device
  */
 static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
 {
@@ -1938,8 +1957,7 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
 	/*
 	 * Set default pool features.
 	 */
-	memset(&pf, 0, sizeof(pf));
-	pf.zero_new_blocks = 1;
+	pool_features_init(&pf);
 
 	dm_consume_args(&as, 4);
 	r = parse_pool_features(&as, &pf, ti);
@@ -1964,10 +1982,12 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
 	pt->metadata_dev = metadata_dev;
 	pt->data_dev = data_dev;
 	pt->low_water_blocks = low_water_blocks;
-	pt->zero_new_blocks = pf.zero_new_blocks;
+	pt->pf = pf;
 	ti->num_flush_requests = 1;
-	ti->num_discard_requests = 1;
-	ti->discards_supported = 1;
+	if (pf.discard_enabled && pf.discard_passdown) {
+		ti->discards_supported = 1;
+		ti->num_discard_requests = 1;
+	}
 	ti->private = pt;
 
 	pt->callbacks.congested_fn = pool_is_congested;
@@ -2303,7 +2323,7 @@ static int pool_message(struct dm_target *ti, unsigned argc, char **argv)
 static int pool_status(struct dm_target *ti, status_type_t type,
 		       char *result, unsigned maxlen)
 {
-	int r;
+	int r, count;
 	unsigned sz = 0;
 	uint64_t transaction_id;
 	dm_block_t nr_free_blocks_data;
@@ -2366,10 +2386,18 @@ static int pool_status(struct dm_target *ti, status_type_t type,
 		       (unsigned long)pool->sectors_per_block,
 		       (unsigned long long)pt->low_water_blocks);
 
-		DMEMIT("%u ", !pool->zero_new_blocks);
+		count = !pool->pf.zero_new_blocks + !pool->pf.discard_enabled + !pool->pf.discard_passdown;
+		DMEMIT("%u ", count);
 
-		if (!pool->zero_new_blocks)
+		if (!pool->pf.zero_new_blocks)
 			DMEMIT("skip_block_zeroing ");
+
+		if (!pool->pf.discard_enabled)
+			DMEMIT("skip_discard ");
+
+		if (!pool->pf.discard_passdown)
+			DMEMIT("skip_discard_passdown");
+
 		break;
 	}
 
@@ -2407,7 +2435,7 @@ static void set_discard_limits(struct pool *pool, struct queue_limits *limits)
 	 * bios that overlap 2 blocks.
 	 */
 	limits->discard_granularity = pool->sectors_per_block << SECTOR_SHIFT;
-	limits->discard_zeroes_data = pool->zero_new_blocks;
+	limits->discard_zeroes_data = pool->pf.zero_new_blocks;
 }
 
 static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
@@ -2417,7 +2445,8 @@ static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
 
 	blk_limits_io_min(limits, 0);
 	blk_limits_io_opt(limits, pool->sectors_per_block << SECTOR_SHIFT);
-	set_discard_limits(pool, limits);
+	if (pool->pf.discard_enabled)
+		set_discard_limits(pool, limits);
 }
 
 static struct target_type pool_target = {
@@ -2466,6 +2495,8 @@ static void thin_dtr(struct dm_target *ti)
  * pool_dev: the path to the pool (eg, /dev/mapper/my_pool)
  * dev_id: the internal device identifier
  * origin_dev: a device external to the pool that should act as the origin
+ *
+ * If the pool has discards disabled, they get disabled for the thin as well.
  */
 static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
 {
@@ -2534,8 +2565,12 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
 
 	ti->split_io = tc->pool->sectors_per_block;
 	ti->num_flush_requests = 1;
-	ti->num_discard_requests = 1;
-	ti->discards_supported = 1;
+
+	/* In case the pool supports discards, pass them on. */
+	if (tc->pool->pf.discard_enabled) {
+		ti->discards_supported = 1;
+		ti->num_discard_requests = 1;
+	}
 
 	dm_put(pool_md);
 
-- 
1.7.1


[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]