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 /* FIXME make this configurable */
  13 #define DM_MAX_IO_REGIONS 8
  14
  15 struct io_region {
  16         struct block_device *bdev;
  17         sector_t sector;
  18         sector_t count;
  19 };
  20
  21 struct page_list {
  22         struct page_list *next;
  23         struct page *page;
  24 };
  25
  26
  27 /*
  28  * 'error' is a bitset, with each bit indicating whether an error
  29  * occurred doing io to the corresponding region.
  30  */
  31 typedef void (*io_notify_fn)(unsigned long error, void *context);
  32
  33
  34 /*
  35  * Before anyone uses the IO interface they should call
  36  * dm_io_get(), specifying roughly how many pages they are
  37  * expecting to perform io on concurrently.
  38  *
  39  * This function may block.
  40  */
  41 int dm_io_get(unsigned int num_pages);
  42 void dm_io_put(unsigned int num_pages);
  43
  44 /*
  45  * Synchronous IO.
  46  *
  47  * Please ensure that the rw flag in the next two functions is
  48  * either READ or WRITE, ie. we don't take READA.  Any
  49  * regions with a zero count field will be ignored.
  50  */
  51 int dm_io_sync(unsigned int num_regions, struct io_region *where, int rw,
  52                struct page_list *pl, unsigned int offset,
  53                unsigned long *error_bits);
  54
  55 int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw,
  56                     struct bio_vec *bvec, unsigned long *error_bits);
  57
  58 int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
  59                   void *data, unsigned long *error_bits);
  60
  61 /*
  62  * Aynchronous IO.
  63  *
  64  * The 'where' array may be safely allocated on the stack since
  65  * the function takes a copy.
  66  */
  67 int dm_io_async(unsigned int num_regions, struct io_region *where, int rw,
  68                 struct page_list *pl, unsigned int offset,
  69                 io_notify_fn fn, void *context);
  70
  71 int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, int rw,
  72                      struct bio_vec *bvec, io_notify_fn fn, void *context);
  73
  74 int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
  75                    void *data, io_notify_fn fn, void *context);
  76
  77 #endif