dm: unplug queues in threads

[linux-2.6-omap-h63xx.git] / drivers / md / dm-io.c

diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index ed9c86cd053e81f32b5c6551d3246461c00d5d30..4789c42d9a3ac503d53ba6ea77fe7fadbee21682 100644 (file)
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -353,7 +353,7 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions,
 {
        struct io io;
 
-       if (num_regions > 1 && rw != WRITE) {
+       if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
                WARN_ON(1);
                return -EIO;
        }
@@ -390,7 +390,7 @@ static int async_io(struct dm_io_client *client, unsigned int num_regions,
 {
        struct io *io;
 
-       if (num_regions > 1 && rw != WRITE) {
+       if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
                WARN_ON(1);
                fn(1, context);
                return -EIO;
@@ -436,7 +436,12 @@ static int dp_init(struct dm_io_request *io_req, struct dpages *dp)
 }
 
 /*
- * New collapsed (a)synchronous interface
+ * New collapsed (a)synchronous interface.
+ *
+ * If the IO is asynchronous (i.e. it has notify.fn), you must either unplug
+ * the queue with blk_unplug() some time later or set the BIO_RW_SYNC bit in
+ * io_req->bi_rw. If you fail to do one of these, the IO will be submitted to
+ * the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c.
  */
 int dm_io(struct dm_io_request *io_req, unsigned num_regions,
          struct dm_io_region *where, unsigned long *sync_error_bits)