drivers/md/dm-io.h

   1 /*
   2  * Copyright (C) 2003 Sistina Software
   3  *
   4  * This file is released under the GPL.
   5  */
   6
   7 #ifndef _DM_IO_H
   8 #define _DM_IO_H
   9
  10 #include "dm.h"
  11
  12 struct io_region {
  13         struct block_device *bdev;
  14         sector_t sector;
  15         sector_t count;         /* If this is zero the region is ignored. */
  16 };
  17
  18 struct page_list {
  19         struct page_list *next;
  20         struct page *page;
  21 };
  22
  23 typedef void (*io_notify_fn)(unsigned long error, void *context);
  24
  25 enum dm_io_mem_type {
  26         DM_IO_PAGE_LIST,/* Page list */
  27         DM_IO_BVEC,     /* Bio vector */
  28         DM_IO_VMA,      /* Virtual memory area */
  29         DM_IO_KMEM,     /* Kernel memory */
  30 };
  31
  32 struct dm_io_memory {
  33         enum dm_io_mem_type type;
  34
  35         union {
  36                 struct page_list *pl;
  37                 struct bio_vec *bvec;
  38                 void *vma;
  39                 void *addr;
  40         } ptr;
  41
  42         unsigned offset;
  43 };
  44
  45 struct dm_io_notify {
  46         io_notify_fn fn;        /* Callback for asynchronous requests */
  47         void *context;          /* Passed to callback */
  48 };
  49
  50 /*
  51  * IO request structure
  52  */
  53 struct dm_io_client;
  54 struct dm_io_request {
  55         int bi_rw;                      /* READ|WRITE - not READA */
  56         struct dm_io_memory mem;        /* Memory to use for io */
  57         struct dm_io_notify notify;     /* Synchronous if notify.fn is NULL */
  58         struct dm_io_client *client;    /* Client memory handler */
  59 };
  60
  61 /*
  62  * For async io calls, users can alternatively use the dm_io() function below
  63  * and dm_io_client_create() to create private mempools for the client.
  64  *
  65  * Create/destroy may block.
  66  */
  67 struct dm_io_client *dm_io_client_create(unsigned num_pages);
  68 int dm_io_client_resize(unsigned num_pages, struct dm_io_client *client);
  69 void dm_io_client_destroy(struct dm_io_client *client);
  70
  71 /*
  72  * IO interface using private per-client pools.
  73  * Each bit in the optional 'sync_error_bits' bitset indicates whether an
  74  * error occurred doing io to the corresponding region.
  75  */
  76 int dm_io(struct dm_io_request *io_req, unsigned num_regions,
  77           struct io_region *region, unsigned long *sync_error_bits);
  78
  79 #endif