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authorMike Snitzer <snitzer@redhat.com>2011-08-02 12:32:01 +0100
committerAlasdair G Kergon <agk@redhat.com>2011-08-02 12:32:01 +0100
commit936688d7eb0f39be96c5791be1a04994cc8d6aa0 (patch)
tree4001f52284d39f5353174096e76b357f52ee2fb7 /drivers/md
parent283a8328ca5b987e547848de8ff0e28edcfb9e08 (diff)
dm table: fix discard support
Remove 'discards_supported' from the dm_table structure. The same information can be easily discovered from the table's target(s) in dm_table_supports_discards(). Before this fix dm_table_supports_discards() would skip checking the individual targets' 'discards_supported' flag if any one target in the table didn't set num_discard_requests > 0. Now the per-target 'discards_supported' flag is effective at insuring the final DM device advertises discard support. But, to be clear, targets that don't support discards (!num_discard_requests) will not receive discard requests. Also DMWARN if a target sets 'discards_supported' override but forgets to set 'num_discard_requests'. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/dm-table.c15
-rw-r--r--drivers/md/dm.c3
2 files changed, 9 insertions, 9 deletions
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index bfe9c2333ce..3909fa259f5 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -54,7 +54,6 @@ struct dm_table {
sector_t *highs;
struct dm_target *targets;
- unsigned discards_supported:1;
unsigned integrity_supported:1;
/*
@@ -209,7 +208,6 @@ int dm_table_create(struct dm_table **result, fmode_t mode,
INIT_LIST_HEAD(&t->devices);
INIT_LIST_HEAD(&t->target_callbacks);
atomic_set(&t->holders, 0);
- t->discards_supported = 1;
if (!num_targets)
num_targets = KEYS_PER_NODE;
@@ -791,8 +789,9 @@ int dm_table_add_target(struct dm_table *t, const char *type,
t->highs[t->num_targets++] = tgt->begin + tgt->len - 1;
- if (!tgt->num_discard_requests)
- t->discards_supported = 0;
+ if (!tgt->num_discard_requests && tgt->discards_supported)
+ DMWARN("%s: %s: ignoring discards_supported because num_discard_requests is zero.",
+ dm_device_name(t->md), type);
return 0;
@@ -1359,19 +1358,19 @@ bool dm_table_supports_discards(struct dm_table *t)
struct dm_target *ti;
unsigned i = 0;
- if (!t->discards_supported)
- return 0;
-
/*
* Unless any target used by the table set discards_supported,
* require at least one underlying device to support discards.
* t->devices includes internal dm devices such as mirror logs
* so we need to use iterate_devices here, which targets
- * supporting discard must provide.
+ * supporting discard selectively must provide.
*/
while (i < dm_table_get_num_targets(t)) {
ti = dm_table_get_target(t, i++);
+ if (!ti->num_discard_requests)
+ continue;
+
if (ti->discards_supported)
return 1;
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 41abc6dd481..aeb0fa1ccfe 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1179,7 +1179,8 @@ static int __clone_and_map_discard(struct clone_info *ci)
/*
* Even though the device advertised discard support,
- * reconfiguration might have changed that since the
+ * that does not mean every target supports it, and
+ * reconfiguration might also have changed that since the
* check was performed.
*/
if (!ti->num_discard_requests)