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