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;
  16 };
  17
  18 struct page_list {
  19         struct page_list *next;
  20         struct page *page;
  21 };
  22
  23
  24 /*
  25  * 'error' is a bitset, with each bit indicating whether an error
  26  * occurred doing io to the corresponding region.
  27  */
  28 typedef void (*io_notify_fn)(unsigned long error, void *context);
  29
  30
  31 /*
  32  * Before anyone uses the IO interface they should call
  33  * dm_io_get(), specifying roughly how many pages they are
  34  * expecting to perform io on concurrently.
  35  *
  36  * This function may block.
  37  */
  38 int dm_io_get(unsigned int num_pages);
  39 void dm_io_put(unsigned int num_pages);
  40
  41 /*
  42  * Synchronous IO.
  43  *
  44  * Please ensure that the rw flag in the next two functions is
  45  * either READ or WRITE, ie. we don't take READA.  Any
  46  * regions with a zero count field will be ignored.
  47  */
  48 int dm_io_sync(unsigned int num_regions, struct io_region *where, int rw,
  49                struct page_list *pl, unsigned int offset,
  50                unsigned long *error_bits);
  51
  52 int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw,
  53                     struct bio_vec *bvec, unsigned long *error_bits);
  54
  55 int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
  56                   void *data, unsigned long *error_bits);
  57
  58 /*
  59  * Aynchronous IO.
  60  *
  61  * The 'where' array may be safely allocated on the stack since
  62  * the function takes a copy.
  63  */
  64 int dm_io_async(unsigned int num_regions, struct io_region *where, int rw,
  65                 struct page_list *pl, unsigned int offset,
  66                 io_notify_fn fn, void *context);
  67
  68 int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, int rw,
  69                      struct bio_vec *bvec, io_notify_fn fn, void *context);
  70
  71 int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
  72                    void *data, io_notify_fn fn, void *context);
  73
  74 #endif