dm io: new interface

Add a new API to dm-io.c that uses a private mempool and bio_set for each
client.

The new functions to use are dm_io_client_create(), dm_io_client_destroy(),
dm_io_client_resize() and dm_io().

Signed-off-by: Heinz Mauelshagen <hjm@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: Milan Broz <mbroz@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 51 insertions, 1 deletions

diff --git a/drivers/md/dm-io.h b/drivers/md/dm-io.h
index f9035bfd1a9..05b13382558 100644
--- 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
@@ -39,6 +73,16 @@ 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.
  *
  * Please ensure that the rw flag in the next two functions is
@@ -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