dm io: new interface

[cascardo/linux.git] / drivers / md / dm-io.h

diff --git a/drivers/md/dm-io.h b/drivers/md/dm-io.h
index f9035bf..05b1338 100644 (file)
--- a/drivers/md/dm-io.h
+++ b/drivers/md/dm-io.h
@@ -20,13 +20,47 @@ struct page_list {
        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);
 
+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 */
+};
 
 /*
  * Before anyone uses the IO interface they should call
@@ -38,6 +72,16 @@ typedef void (*io_notify_fn)(unsigned long error, void *context);
 int dm_io_get(unsigned int num_pages);
 void dm_io_put(unsigned int num_pages);
 
+/*
+ * 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);
+
 /*
  * Synchronous IO.
  *
@@ -71,4 +115,10 @@ int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, int rw,
 int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
                   void *data, io_notify_fn fn, void *context);
 
+/*
+ * IO interface using private per-client pools.
+ */
+int dm_io(struct dm_io_request *io_req, unsigned num_regions,
+         struct io_region *region, unsigned long *sync_error_bits);
+
 #endif