include/linux/dm-io.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2003 Sistina Software
   4  * Copyright (C) 2004 - 2008 Red Hat, Inc. All rights reserved.
   5  *
   6  * Device-Mapper low-level I/O.
   7  *
   8  * This file is released under the GPL.
   9  */
  10
  11 #ifndef _LINUX_DM_IO_H
  12 #define _LINUX_DM_IO_H
  13
  14 #ifdef __KERNEL__
  15
  16 #include <linux/types.h>
  17 #include <linux/blk_types.h>
  18
  19 struct dm_io_region {
  20         struct block_device *bdev;
  21         sector_t sector;
  22         sector_t count;         /* If this is zero the region is ignored. */
  23 };
  24
  25 struct page_list {
  26         struct page_list *next;
  27         struct page *page;
  28 };
  29
  30 typedef void (*io_notify_fn)(unsigned int long error, void *context);
  31
  32 enum dm_io_mem_type {
  33         DM_IO_PAGE_LIST,/* Page list */
  34         DM_IO_BIO,      /* Bio vector */
  35         DM_IO_VMA,      /* Virtual memory area */
  36         DM_IO_KMEM,     /* Kernel memory */
  37 };
  38
  39 struct dm_io_memory {
  40         enum dm_io_mem_type type;
  41
  42         unsigned int offset;
  43
  44         union {
  45                 struct page_list *pl;
  46                 struct bio *bio;
  47                 void *vma;
  48                 void *addr;
  49         } ptr;
  50 };
  51
  52 struct dm_io_notify {
  53         io_notify_fn fn;        /* Callback for asynchronous requests */
  54         void *context;          /* Passed to callback */
  55 };
  56
  57 /*
  58  * IO request structure
  59  */
  60 struct dm_io_client;
  61 struct dm_io_request {
  62         blk_opf_t           bi_opf;     /* Request type and flags */
  63         struct dm_io_memory mem;        /* Memory to use for io */
  64         struct dm_io_notify notify;     /* Synchronous if notify.fn is NULL */
  65         struct dm_io_client *client;    /* Client memory handler */
  66 };
  67
  68 /*
  69  * For async io calls, users can alternatively use the dm_io() function below
  70  * and dm_io_client_create() to create private mempools for the client.
  71  *
  72  * Create/destroy may block.
  73  */
  74 struct dm_io_client *dm_io_client_create(void);
  75 void dm_io_client_destroy(struct dm_io_client *client);
  76
  77 /*
  78  * IO interface using private per-client pools.
  79  * Each bit in the optional 'sync_error_bits' bitset indicates whether an
  80  * error occurred doing io to the corresponding region.
  81  */
  82 int dm_io(struct dm_io_request *io_req, unsigned int num_regions,
  83           struct dm_io_region *region, unsigned int long *sync_error_bits,
  84           unsigned short ioprio);
  85
  86 #endif  /* __KERNEL__ */
  87 #endif  /* _LINUX_DM_IO_H */