1 files changed, 77 insertions, 0 deletions
diff --git a/drivers/md/dm-io.h b/drivers/md/dm-io.h
new file mode 100644
index 000000000000..1a77f3265706
--- /dev/null
+++ b/drivers/md/dm-io.h
@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2003 Sistina Software
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef _DM_IO_H
+#define _DM_IO_H
+
+#include "dm.h"
+
+/* FIXME make this configurable */
+#define DM_MAX_IO_REGIONS 8
+
+struct io_region {
+	struct block_device *bdev;
+	sector_t sector;
+	sector_t count;
+};
+
+struct page_list {
+	struct page_list *next;
+	struct page *page;
+};
+
+
+/*
+ * 'error' is a bitset, with each bit indicating whether an error
+ * occurred doing io to the corresponding region.
+ */
+typedef void (*io_notify_fn)(unsigned long error, void *context);
+
+
+/*
+ * Before anyone uses the IO interface they should call
+ * dm_io_get(), specifying roughly how many pages they are
+ * expecting to perform io on concurrently.
+ *
+ * This function may block.
+ */
+int dm_io_get(unsigned int num_pages);
+void dm_io_put(unsigned int num_pages);
+
+/*
+ * Synchronous IO.
+ *
+ * Please ensure that the rw flag in the next two functions is
+ * either READ or WRITE, ie. we don't take READA.  Any
+ * regions with a zero count field will be ignored.
+ */
+int dm_io_sync(unsigned int num_regions, struct io_region *where, int rw,
+	       struct page_list *pl, unsigned int offset,
+	       unsigned long *error_bits);
+
+int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw,
+		    struct bio_vec *bvec, unsigned long *error_bits);
+
+int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
+		  void *data, unsigned long *error_bits);
+
+/*
+ * Aynchronous IO.
+ *
+ * The 'where' array may be safely allocated on the stack since
+ * the function takes a copy.
+ */
+int dm_io_async(unsigned int num_regions, struct io_region *where, int rw,
+		struct page_list *pl, unsigned int offset,
+		io_notify_fn fn, void *context);
+
+int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, int rw,
+		     struct bio_vec *bvec, io_notify_fn fn, void *context);
+
+int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
+		   void *data, io_notify_fn fn, void *context);
+
+#endif