1 files changed, 85 insertions, 0 deletions

diff --git a/include/linux/dm-io.h b/include/linux/dm-io.h
new file mode 100644
index 000000000000..b6bf17ee2f61
--- /dev/null
+++ b/include/linux/dm-io.h
@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2003 Sistina Software
+ * Copyright (C) 2004 - 2008 Red Hat, Inc. All rights reserved.
+ *
+ * Device-Mapper low-level I/O.
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef _LINUX_DM_IO_H
+#define _LINUX_DM_IO_H
+
+#ifdef __KERNEL__
+
+#include <linux/types.h>
+
+struct dm_io_region {
+        struct block_device *bdev;
+        sector_t sector;
+        sector_t count;         /* If this is zero the region is ignored. */
+};
+
+struct page_list {
+        struct page_list *next;
+        struct page *page;
+};
+
+typedef void (*io_notify_fn)(unsigned long error, void *context);
+
+enum dm_io_mem_type {
+        DM_IO_PAGE_LIST,/* Page list */
+        DM_IO_BVEC,     /* Bio vector */
+        DM_IO_VMA,      /* Virtual memory area */
+        DM_IO_KMEM,     /* Kernel memory */
+};
+
+struct dm_io_memory {
+        enum dm_io_mem_type type;
+
+        union {
+                struct page_list *pl;
+                struct bio_vec *bvec;
+                void *vma;
+                void *addr;
+        } ptr;
+
+        unsigned offset;
+};
+
+struct dm_io_notify {
+        io_notify_fn fn;        /* Callback for asynchronous requests */
+        void *context;          /* Passed to callback */
+};
+
+/*
+ * IO request structure
+ */
+struct dm_io_client;
+struct dm_io_request {
+        int bi_rw;                      /* READ|WRITE - not READA */
+        struct dm_io_memory mem;        /* Memory to use for io */
+        struct dm_io_notify notify;     /* Synchronous if notify.fn is NULL */
+        struct dm_io_client *client;    /* Client memory handler */
+};
+
+/*
+ * For async io calls, users can alternatively use the dm_io() function below
+ * and dm_io_client_create() to create private mempools for the client.
+ *
+ * Create/destroy may block.
+ */
+struct dm_io_client *dm_io_client_create(unsigned num_pages);
+int dm_io_client_resize(unsigned num_pages, struct dm_io_client *client);
+void dm_io_client_destroy(struct dm_io_client *client);
+
+/*
+ * IO interface using private per-client pools.
+ * Each bit in the optional 'sync_error_bits' bitset indicates whether an
+ * error occurred doing io to the corresponding region.
+ */
+int dm_io(struct dm_io_request *io_req, unsigned num_regions,
+          struct dm_io_region *region, unsigned long *sync_error_bits);
+
+#endif  /* __KERNEL__ */
+#endif  /* _LINUX_DM_IO_H */