dm table: propagate BDI_CAP_STABLE_WRITES to fix sporadic checksum errors
[muen/linux.git] / drivers / md / dm-table.c
index ba9481f..cde3b49 100644 (file)
@@ -1844,6 +1844,36 @@ static bool dm_table_supports_secure_erase(struct dm_table *t)
        return true;
 }
 
+static int device_requires_stable_pages(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 && bdi_cap_stable_pages_required(q->backing_dev_info);
+}
+
+/*
+ * If any underlying device requires stable pages, a table must require
+ * them as well.  Only targets that support iterate_devices are considered:
+ * don't want error, zero, etc to require stable pages.
+ */
+static bool dm_table_requires_stable_pages(struct dm_table *t)
+{
+       struct dm_target *ti;
+       unsigned i;
+
+       for (i = 0; i < dm_table_get_num_targets(t); i++) {
+               ti = dm_table_get_target(t, i);
+
+               if (ti->type->iterate_devices &&
+                   ti->type->iterate_devices(ti, device_requires_stable_pages, NULL))
+                       return true;
+       }
+
+       return false;
+}
+
 void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
                               struct queue_limits *limits)
 {
@@ -1896,6 +1926,15 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 
        dm_table_verify_integrity(t);
 
+       /*
+        * Some devices don't use blk_integrity but still want stable pages
+        * because they do their own checksumming.
+        */
+       if (dm_table_requires_stable_pages(t))
+               q->backing_dev_info->capabilities |= BDI_CAP_STABLE_WRITES;
+       else
+               q->backing_dev_info->capabilities &= ~BDI_CAP_STABLE_WRITES;
+
        /*
         * Determine whether or not this queue's I/O timings contribute
         * to the entropy pool, Only request-based targets use this.