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 f9035bfd1a9f..05b133825580 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