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 */
88