ia64/xen-unstable

view tools/ioemu/block-cow.c @ 8740:3d7ea7972b39

Update patches for linux 2.6.15.

Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
author cl349@firebug.cl.cam.ac.uk
date Thu Feb 02 17:16:00 2006 +0000 (2006-02-02)
parents 8e5fc5fe636c
children f7b43e5c42b9
line source
1 /*
2 * Block driver for the COW format
3 *
4 * Copyright (c) 2004 Fabrice Bellard
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
23 */
24 #ifndef _WIN32
25 #include "vl.h"
26 #include "block_int.h"
27 #include <sys/mman.h>
29 /**************************************************************/
30 /* COW block driver using file system holes */
32 /* user mode linux compatible COW file */
33 #define COW_MAGIC 0x4f4f4f4d /* MOOO */
34 #define COW_VERSION 2
36 struct cow_header_v2 {
37 uint32_t magic;
38 uint32_t version;
39 char backing_file[1024];
40 int32_t mtime;
41 uint64_t size;
42 uint32_t sectorsize;
43 };
45 typedef struct BDRVCowState {
46 int fd;
47 uint8_t *cow_bitmap; /* if non NULL, COW mappings are used first */
48 uint8_t *cow_bitmap_addr; /* mmap address of cow_bitmap */
49 int cow_bitmap_size;
50 int64_t cow_sectors_offset;
51 } BDRVCowState;
53 static int cow_probe(const uint8_t *buf, int buf_size, const char *filename)
54 {
55 const struct cow_header_v2 *cow_header = (const void *)buf;
57 if (be32_to_cpu(cow_header->magic) == COW_MAGIC &&
58 be32_to_cpu(cow_header->version) == COW_VERSION)
59 return 100;
60 else
61 return 0;
62 }
64 static int cow_open(BlockDriverState *bs, const char *filename)
65 {
66 BDRVCowState *s = bs->opaque;
67 int fd;
68 struct cow_header_v2 cow_header;
69 int64_t size;
71 fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE);
72 if (fd < 0) {
73 fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
74 if (fd < 0)
75 return -1;
76 }
77 s->fd = fd;
78 /* see if it is a cow image */
79 if (read(fd, &cow_header, sizeof(cow_header)) != sizeof(cow_header)) {
80 goto fail;
81 }
83 if (be32_to_cpu(cow_header.magic) != COW_MAGIC ||
84 be32_to_cpu(cow_header.version) != COW_VERSION) {
85 goto fail;
86 }
88 /* cow image found */
89 size = be64_to_cpu(cow_header.size);
90 bs->total_sectors = size / 512;
92 pstrcpy(bs->backing_file, sizeof(bs->backing_file),
93 cow_header.backing_file);
95 #if 0
96 if (cow_header.backing_file[0] != '\0') {
97 if (stat(cow_header.backing_file, &st) != 0) {
98 fprintf(stderr, "%s: could not find original disk image '%s'\n", filename, cow_header.backing_file);
99 goto fail;
100 }
101 if (st.st_mtime != be32_to_cpu(cow_header.mtime)) {
102 fprintf(stderr, "%s: original raw disk image '%s' does not match saved timestamp\n", filename, cow_header.backing_file);
103 goto fail;
104 }
105 fd = open(cow_header.backing_file, O_RDONLY | O_LARGEFILE);
106 if (fd < 0)
107 goto fail;
108 bs->fd = fd;
109 }
110 #endif
111 /* mmap the bitmap */
112 s->cow_bitmap_size = ((bs->total_sectors + 7) >> 3) + sizeof(cow_header);
113 s->cow_bitmap_addr = mmap(get_mmap_addr(s->cow_bitmap_size),
114 s->cow_bitmap_size,
115 PROT_READ | PROT_WRITE,
116 MAP_SHARED, s->fd, 0);
117 if (s->cow_bitmap_addr == MAP_FAILED)
118 goto fail;
119 s->cow_bitmap = s->cow_bitmap_addr + sizeof(cow_header);
120 s->cow_sectors_offset = (s->cow_bitmap_size + 511) & ~511;
121 return 0;
122 fail:
123 close(fd);
124 return -1;
125 }
127 static inline void set_bit(uint8_t *bitmap, int64_t bitnum)
128 {
129 bitmap[bitnum / 8] |= (1 << (bitnum%8));
130 }
132 static inline int is_bit_set(const uint8_t *bitmap, int64_t bitnum)
133 {
134 return !!(bitmap[bitnum / 8] & (1 << (bitnum%8)));
135 }
138 /* Return true if first block has been changed (ie. current version is
139 * in COW file). Set the number of continuous blocks for which that
140 * is true. */
141 static inline int is_changed(uint8_t *bitmap,
142 int64_t sector_num, int nb_sectors,
143 int *num_same)
144 {
145 int changed;
147 if (!bitmap || nb_sectors == 0) {
148 *num_same = nb_sectors;
149 return 0;
150 }
152 changed = is_bit_set(bitmap, sector_num);
153 for (*num_same = 1; *num_same < nb_sectors; (*num_same)++) {
154 if (is_bit_set(bitmap, sector_num + *num_same) != changed)
155 break;
156 }
158 return changed;
159 }
161 static int cow_is_allocated(BlockDriverState *bs, int64_t sector_num,
162 int nb_sectors, int *pnum)
163 {
164 BDRVCowState *s = bs->opaque;
165 return is_changed(s->cow_bitmap, sector_num, nb_sectors, pnum);
166 }
168 static int cow_read(BlockDriverState *bs, int64_t sector_num,
169 uint8_t *buf, int nb_sectors)
170 {
171 BDRVCowState *s = bs->opaque;
172 int ret, n;
174 while (nb_sectors > 0) {
175 if (is_changed(s->cow_bitmap, sector_num, nb_sectors, &n)) {
176 lseek(s->fd, s->cow_sectors_offset + sector_num * 512, SEEK_SET);
177 ret = read(s->fd, buf, n * 512);
178 if (ret != n * 512)
179 return -1;
180 } else {
181 memset(buf, 0, n * 512);
182 }
183 nb_sectors -= n;
184 sector_num += n;
185 buf += n * 512;
186 }
187 return 0;
188 }
190 static int cow_write(BlockDriverState *bs, int64_t sector_num,
191 const uint8_t *buf, int nb_sectors)
192 {
193 BDRVCowState *s = bs->opaque;
194 int ret, i;
196 lseek(s->fd, s->cow_sectors_offset + sector_num * 512, SEEK_SET);
197 ret = write(s->fd, buf, nb_sectors * 512);
198 if (ret != nb_sectors * 512)
199 return -1;
200 for (i = 0; i < nb_sectors; i++)
201 set_bit(s->cow_bitmap, sector_num + i);
202 return 0;
203 }
205 static void cow_close(BlockDriverState *bs)
206 {
207 BDRVCowState *s = bs->opaque;
208 munmap(s->cow_bitmap_addr, s->cow_bitmap_size);
209 close(s->fd);
210 }
212 static int cow_create(const char *filename, int64_t image_sectors,
213 const char *image_filename, int flags)
214 {
215 int fd, cow_fd;
216 struct cow_header_v2 cow_header;
217 struct stat st;
219 if (flags)
220 return -ENOTSUP;
222 cow_fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
223 0644);
224 if (cow_fd < 0)
225 return -1;
226 memset(&cow_header, 0, sizeof(cow_header));
227 cow_header.magic = cpu_to_be32(COW_MAGIC);
228 cow_header.version = cpu_to_be32(COW_VERSION);
229 if (image_filename) {
230 fd = open(image_filename, O_RDONLY | O_BINARY);
231 if (fd < 0) {
232 close(cow_fd);
233 return -1;
234 }
235 if (fstat(fd, &st) != 0) {
236 close(fd);
237 return -1;
238 }
239 close(fd);
240 cow_header.mtime = cpu_to_be32(st.st_mtime);
241 realpath(image_filename, cow_header.backing_file);
242 }
243 cow_header.sectorsize = cpu_to_be32(512);
244 cow_header.size = cpu_to_be64(image_sectors * 512);
245 write(cow_fd, &cow_header, sizeof(cow_header));
246 /* resize to include at least all the bitmap */
247 ftruncate(cow_fd, sizeof(cow_header) + ((image_sectors + 7) >> 3));
248 close(cow_fd);
249 return 0;
250 }
252 BlockDriver bdrv_cow = {
253 "cow",
254 sizeof(BDRVCowState),
255 cow_probe,
256 cow_open,
257 cow_read,
258 cow_write,
259 cow_close,
260 cow_create,
261 cow_is_allocated,
262 };
263 #endif