[PATCH] optimise loop driver a bit
[linux-2.6.git] / include / linux / loop.h
1 #ifndef _LINUX_LOOP_H
2 #define _LINUX_LOOP_H
3
4 /*
5  * include/linux/loop.h
6  *
7  * Written by Theodore Ts'o, 3/29/93.
8  *
9  * Copyright 1993 by Theodore Ts'o.  Redistribution of this file is
10  * permitted under the GNU General Public License.
11  */
12
13 #define LO_NAME_SIZE    64
14 #define LO_KEY_SIZE     32
15
16 #ifdef __KERNEL__
17 #include <linux/bio.h>
18 #include <linux/blkdev.h>
19 #include <linux/spinlock.h>
20
21 /* Possible states of device */
22 enum {
23         Lo_unbound,
24         Lo_bound,
25         Lo_rundown,
26 };
27
28 struct loop_func_table;
29
30 struct loop_device {
31         int             lo_number;
32         int             lo_refcnt;
33         loff_t          lo_offset;
34         loff_t          lo_sizelimit;
35         int             lo_flags;
36         int             (*transfer)(struct loop_device *, int cmd,
37                                     struct page *raw_page, unsigned raw_off,
38                                     struct page *loop_page, unsigned loop_off,
39                                     int size, sector_t real_block);
40         char            lo_file_name[LO_NAME_SIZE];
41         char            lo_crypt_name[LO_NAME_SIZE];
42         char            lo_encrypt_key[LO_KEY_SIZE];
43         int             lo_encrypt_key_size;
44         struct loop_func_table *lo_encryption;
45         __u32           lo_init[2];
46         uid_t           lo_key_owner;   /* Who set the key */
47         int             (*ioctl)(struct loop_device *, int cmd, 
48                                  unsigned long arg); 
49
50         struct file *   lo_backing_file;
51         struct block_device *lo_device;
52         unsigned        lo_blocksize;
53         void            *key_data; 
54
55         int             old_gfp_mask;
56
57         spinlock_t              lo_lock;
58         struct bio              *lo_bio;
59         struct bio              *lo_biotail;
60         int                     lo_state;
61         struct semaphore        lo_sem;
62         struct semaphore        lo_ctl_mutex;
63         struct semaphore        lo_bh_mutex;
64         int                     lo_pending;
65
66         request_queue_t         *lo_queue;
67 };
68
69 #endif /* __KERNEL__ */
70
71 /*
72  * Loop flags
73  */
74 enum {
75         LO_FLAGS_READ_ONLY      = 1,
76         LO_FLAGS_USE_AOPS       = 2,
77 };
78
79 #include <asm/posix_types.h>    /* for __kernel_old_dev_t */
80 #include <asm/types.h>          /* for __u64 */
81
82 /* Backwards compatibility version */
83 struct loop_info {
84         int                lo_number;           /* ioctl r/o */
85         __kernel_old_dev_t lo_device;           /* ioctl r/o */
86         unsigned long      lo_inode;            /* ioctl r/o */
87         __kernel_old_dev_t lo_rdevice;          /* ioctl r/o */
88         int                lo_offset;
89         int                lo_encrypt_type;
90         int                lo_encrypt_key_size;         /* ioctl w/o */
91         int                lo_flags;                    /* ioctl r/o */
92         char               lo_name[LO_NAME_SIZE];
93         unsigned char      lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
94         unsigned long      lo_init[2];
95         char               reserved[4];
96 };
97
98 struct loop_info64 {
99         __u64              lo_device;                   /* ioctl r/o */
100         __u64              lo_inode;                    /* ioctl r/o */
101         __u64              lo_rdevice;                  /* ioctl r/o */
102         __u64              lo_offset;
103         __u64              lo_sizelimit;/* bytes, 0 == max available */
104         __u32              lo_number;                   /* ioctl r/o */
105         __u32              lo_encrypt_type;
106         __u32              lo_encrypt_key_size;         /* ioctl w/o */
107         __u32              lo_flags;                    /* ioctl r/o */
108         __u8               lo_file_name[LO_NAME_SIZE];
109         __u8               lo_crypt_name[LO_NAME_SIZE];
110         __u8               lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
111         __u64              lo_init[2];
112 };
113
114 /*
115  * Loop filter types
116  */
117
118 #define LO_CRYPT_NONE           0
119 #define LO_CRYPT_XOR            1
120 #define LO_CRYPT_DES            2
121 #define LO_CRYPT_FISH2          3    /* Twofish encryption */
122 #define LO_CRYPT_BLOW           4
123 #define LO_CRYPT_CAST128        5
124 #define LO_CRYPT_IDEA           6
125 #define LO_CRYPT_DUMMY          9
126 #define LO_CRYPT_SKIPJACK       10
127 #define LO_CRYPT_CRYPTOAPI      18
128 #define MAX_LO_CRYPT            20
129
130 #ifdef __KERNEL__
131 /* Support for loadable transfer modules */
132 struct loop_func_table {
133         int number;     /* filter type */ 
134         int (*transfer)(struct loop_device *lo, int cmd,
135                         struct page *raw_page, unsigned raw_off,
136                         struct page *loop_page, unsigned loop_off,
137                         int size, sector_t real_block);
138         int (*init)(struct loop_device *, const struct loop_info64 *); 
139         /* release is called from loop_unregister_transfer or clr_fd */
140         int (*release)(struct loop_device *); 
141         int (*ioctl)(struct loop_device *, int cmd, unsigned long arg);
142         struct module *owner;
143 }; 
144
145 int loop_register_transfer(struct loop_func_table *funcs);
146 int loop_unregister_transfer(int number); 
147
148 #endif
149 /*
150  * IOCTL commands --- we will commandeer 0x4C ('L')
151  */
152
153 #define LOOP_SET_FD             0x4C00
154 #define LOOP_CLR_FD             0x4C01
155 #define LOOP_SET_STATUS         0x4C02
156 #define LOOP_GET_STATUS         0x4C03
157 #define LOOP_SET_STATUS64       0x4C04
158 #define LOOP_GET_STATUS64       0x4C05
159 #define LOOP_CHANGE_FD          0x4C06
160
161 #endif