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: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index d420923..e99f413 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -509,9 +509,9 @@
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 @@
/*----------------------------------------------------------------
* 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 @@
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 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 @@
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 @@
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 @@
*/
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