Merge branch 'for-2.6.37/core' of git://git.kernel.dk/linux-2.6-block

[karo-tx-linux.git] / drivers / md / dm-table.c

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index bc60ef77a0d8dc85d632d8c756e0e7af6d688ed9..90267f8d64eeadf5d9e72afae174f6d4b22e6bf5 100644 (file)
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -54,6 +54,8 @@ struct dm_table {
        sector_t *highs;
        struct dm_target *targets;
 
+       unsigned discards_supported:1;
+
        /*
         * Indicates the rw permissions for the new logical
         * device.  This should be a combination of FMODE_READ
@@ -203,6 +205,7 @@ int dm_table_create(struct dm_table **result, fmode_t mode,
 
        INIT_LIST_HEAD(&t->devices);
        atomic_set(&t->holders, 0);
+       t->discards_supported = 1;
 
        if (!num_targets)
                num_targets = KEYS_PER_NODE;
@@ -483,11 +486,6 @@ static int __table_get_device(struct dm_table *t, struct dm_target *ti,
        return 0;
 }
 
-/*
- * Returns the minimum that is _not_ zero, unless both are zero.
- */
-#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
-
 int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
                         sector_t start, sector_t len, void *data)
 {
@@ -770,6 +768,9 @@ 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;
+
        return 0;
 
  bad:
@@ -1135,6 +1136,11 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
        else
                queue_flag_set_unlocked(QUEUE_FLAG_CLUSTER, q);
 
+       if (!dm_table_supports_discards(t))
+               queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
+       else
+               queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
+
        dm_table_set_integrity(t);
 
        /*
@@ -1281,6 +1287,39 @@ struct mapped_device *dm_table_get_md(struct dm_table *t)
        return t->md;
 }
 
+static int device_discard_capable(struct dm_target *ti, struct dm_dev *dev,
+                                 sector_t start, sector_t len, void *data)
+{
+       struct request_queue *q = bdev_get_queue(dev->bdev);
+
+       return q && blk_queue_discard(q);
+}
+
+bool dm_table_supports_discards(struct dm_table *t)
+{
+       struct dm_target *ti;
+       unsigned i = 0;
+
+       if (!t->discards_supported)
+               return 0;
+
+       /*
+        * Ensure that at least one underlying device supports 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.
+        */
+       while (i < dm_table_get_num_targets(t)) {
+               ti = dm_table_get_target(t, i++);
+
+               if (ti->type->iterate_devices &&
+                   ti->type->iterate_devices(ti, device_discard_capable, NULL))
+                       return 1;
+       }
+
+       return 0;
+}
+
 EXPORT_SYMBOL(dm_vcalloc);
 EXPORT_SYMBOL(dm_get_device);
 EXPORT_SYMBOL(dm_put_device);