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1 | ea2384d3 | bellard | /*
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2 | ea2384d3 | bellard | * Block driver for the COW format
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3 | 5fafdf24 | ths | *
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4 | ea2384d3 | bellard | * Copyright (c) 2004 Fabrice Bellard
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5 | 5fafdf24 | ths | *
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6 | ea2384d3 | bellard | * Permission is hereby granted, free of charge, to any person obtaining a copy
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7 | ea2384d3 | bellard | * of this software and associated documentation files (the "Software"), to deal
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8 | ea2384d3 | bellard | * in the Software without restriction, including without limitation the rights
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9 | ea2384d3 | bellard | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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10 | ea2384d3 | bellard | * copies of the Software, and to permit persons to whom the Software is
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11 | ea2384d3 | bellard | * furnished to do so, subject to the following conditions:
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12 | ea2384d3 | bellard | *
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13 | ea2384d3 | bellard | * The above copyright notice and this permission notice shall be included in
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14 | ea2384d3 | bellard | * all copies or substantial portions of the Software.
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15 | ea2384d3 | bellard | *
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16 | ea2384d3 | bellard | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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17 | ea2384d3 | bellard | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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18 | ea2384d3 | bellard | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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19 | ea2384d3 | bellard | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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20 | ea2384d3 | bellard | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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21 | ea2384d3 | bellard | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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22 | ea2384d3 | bellard | * THE SOFTWARE.
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23 | ea2384d3 | bellard | */
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24 | ea2384d3 | bellard | #ifndef _WIN32
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25 | faf07963 | pbrook | #include "qemu-common.h" |
26 | ea2384d3 | bellard | #include "block_int.h" |
27 | 5efa9d5a | Anthony Liguori | #include "module.h" |
28 | ea2384d3 | bellard | #include <sys/mman.h> |
29 | ea2384d3 | bellard | |
30 | ea2384d3 | bellard | /**************************************************************/
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31 | ea2384d3 | bellard | /* COW block driver using file system holes */
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32 | ea2384d3 | bellard | |
33 | ea2384d3 | bellard | /* user mode linux compatible COW file */
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34 | ea2384d3 | bellard | #define COW_MAGIC 0x4f4f4f4d /* MOOO */ |
35 | ea2384d3 | bellard | #define COW_VERSION 2 |
36 | ea2384d3 | bellard | |
37 | ea2384d3 | bellard | struct cow_header_v2 {
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38 | ea2384d3 | bellard | uint32_t magic; |
39 | ea2384d3 | bellard | uint32_t version; |
40 | ea2384d3 | bellard | char backing_file[1024]; |
41 | ea2384d3 | bellard | int32_t mtime; |
42 | ea2384d3 | bellard | uint64_t size; |
43 | ea2384d3 | bellard | uint32_t sectorsize; |
44 | ea2384d3 | bellard | }; |
45 | ea2384d3 | bellard | |
46 | ea2384d3 | bellard | typedef struct BDRVCowState { |
47 | ea2384d3 | bellard | int fd;
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48 | ea2384d3 | bellard | uint8_t *cow_bitmap; /* if non NULL, COW mappings are used first */
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49 | ea2384d3 | bellard | uint8_t *cow_bitmap_addr; /* mmap address of cow_bitmap */
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50 | ea2384d3 | bellard | int cow_bitmap_size;
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51 | ea2384d3 | bellard | int64_t cow_sectors_offset; |
52 | ea2384d3 | bellard | } BDRVCowState; |
53 | ea2384d3 | bellard | |
54 | ea2384d3 | bellard | static int cow_probe(const uint8_t *buf, int buf_size, const char *filename) |
55 | ea2384d3 | bellard | { |
56 | ea2384d3 | bellard | const struct cow_header_v2 *cow_header = (const void *)buf; |
57 | ea2384d3 | bellard | |
58 | 712e7874 | bellard | if (buf_size >= sizeof(struct cow_header_v2) && |
59 | 712e7874 | bellard | be32_to_cpu(cow_header->magic) == COW_MAGIC && |
60 | 5fafdf24 | ths | be32_to_cpu(cow_header->version) == COW_VERSION) |
61 | ea2384d3 | bellard | return 100; |
62 | ea2384d3 | bellard | else
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63 | ea2384d3 | bellard | return 0; |
64 | ea2384d3 | bellard | } |
65 | ea2384d3 | bellard | |
66 | 83f64091 | bellard | static int cow_open(BlockDriverState *bs, const char *filename, int flags) |
67 | ea2384d3 | bellard | { |
68 | ea2384d3 | bellard | BDRVCowState *s = bs->opaque; |
69 | ea2384d3 | bellard | int fd;
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70 | ea2384d3 | bellard | struct cow_header_v2 cow_header;
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71 | ea2384d3 | bellard | int64_t size; |
72 | ea2384d3 | bellard | |
73 | ea2384d3 | bellard | fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE); |
74 | ea2384d3 | bellard | if (fd < 0) { |
75 | ea2384d3 | bellard | fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE); |
76 | ea2384d3 | bellard | if (fd < 0) |
77 | ea2384d3 | bellard | return -1; |
78 | ea2384d3 | bellard | } |
79 | ea2384d3 | bellard | s->fd = fd; |
80 | ea2384d3 | bellard | /* see if it is a cow image */
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81 | ea2384d3 | bellard | if (read(fd, &cow_header, sizeof(cow_header)) != sizeof(cow_header)) { |
82 | ea2384d3 | bellard | goto fail;
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83 | ea2384d3 | bellard | } |
84 | ea2384d3 | bellard | |
85 | ea2384d3 | bellard | if (be32_to_cpu(cow_header.magic) != COW_MAGIC ||
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86 | ea2384d3 | bellard | be32_to_cpu(cow_header.version) != COW_VERSION) { |
87 | ea2384d3 | bellard | goto fail;
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88 | ea2384d3 | bellard | } |
89 | 3b46e624 | ths | |
90 | ea2384d3 | bellard | /* cow image found */
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91 | ea2384d3 | bellard | size = be64_to_cpu(cow_header.size); |
92 | ea2384d3 | bellard | bs->total_sectors = size / 512;
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93 | ea2384d3 | bellard | |
94 | 5fafdf24 | ths | pstrcpy(bs->backing_file, sizeof(bs->backing_file),
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95 | ea2384d3 | bellard | cow_header.backing_file); |
96 | 3b46e624 | ths | |
97 | ea2384d3 | bellard | /* mmap the bitmap */
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98 | ea2384d3 | bellard | s->cow_bitmap_size = ((bs->total_sectors + 7) >> 3) + sizeof(cow_header); |
99 | 3f4cb3d3 | blueswir1 | s->cow_bitmap_addr = (void *)mmap(get_mmap_addr(s->cow_bitmap_size),
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100 | 3f4cb3d3 | blueswir1 | s->cow_bitmap_size, |
101 | 3f4cb3d3 | blueswir1 | PROT_READ | PROT_WRITE, |
102 | 3f4cb3d3 | blueswir1 | MAP_SHARED, s->fd, 0);
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103 | ea2384d3 | bellard | if (s->cow_bitmap_addr == MAP_FAILED)
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104 | ea2384d3 | bellard | goto fail;
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105 | ea2384d3 | bellard | s->cow_bitmap = s->cow_bitmap_addr + sizeof(cow_header);
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106 | ea2384d3 | bellard | s->cow_sectors_offset = (s->cow_bitmap_size + 511) & ~511; |
107 | ea2384d3 | bellard | return 0; |
108 | ea2384d3 | bellard | fail:
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109 | ea2384d3 | bellard | close(fd); |
110 | ea2384d3 | bellard | return -1; |
111 | ea2384d3 | bellard | } |
112 | ea2384d3 | bellard | |
113 | 2b03a7a5 | bellard | static inline void cow_set_bit(uint8_t *bitmap, int64_t bitnum) |
114 | ea2384d3 | bellard | { |
115 | ea2384d3 | bellard | bitmap[bitnum / 8] |= (1 << (bitnum%8)); |
116 | ea2384d3 | bellard | } |
117 | ea2384d3 | bellard | |
118 | ea2384d3 | bellard | static inline int is_bit_set(const uint8_t *bitmap, int64_t bitnum) |
119 | ea2384d3 | bellard | { |
120 | ea2384d3 | bellard | return !!(bitmap[bitnum / 8] & (1 << (bitnum%8))); |
121 | ea2384d3 | bellard | } |
122 | ea2384d3 | bellard | |
123 | ea2384d3 | bellard | |
124 | ea2384d3 | bellard | /* Return true if first block has been changed (ie. current version is
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125 | ea2384d3 | bellard | * in COW file). Set the number of continuous blocks for which that
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126 | ea2384d3 | bellard | * is true. */
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127 | ea2384d3 | bellard | static inline int is_changed(uint8_t *bitmap, |
128 | ea2384d3 | bellard | int64_t sector_num, int nb_sectors,
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129 | ea2384d3 | bellard | int *num_same)
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130 | ea2384d3 | bellard | { |
131 | ea2384d3 | bellard | int changed;
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132 | ea2384d3 | bellard | |
133 | ea2384d3 | bellard | if (!bitmap || nb_sectors == 0) { |
134 | ea2384d3 | bellard | *num_same = nb_sectors; |
135 | ea2384d3 | bellard | return 0; |
136 | ea2384d3 | bellard | } |
137 | ea2384d3 | bellard | |
138 | ea2384d3 | bellard | changed = is_bit_set(bitmap, sector_num); |
139 | ea2384d3 | bellard | for (*num_same = 1; *num_same < nb_sectors; (*num_same)++) { |
140 | ea2384d3 | bellard | if (is_bit_set(bitmap, sector_num + *num_same) != changed)
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141 | ea2384d3 | bellard | break;
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142 | ea2384d3 | bellard | } |
143 | ea2384d3 | bellard | |
144 | ea2384d3 | bellard | return changed;
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145 | ea2384d3 | bellard | } |
146 | ea2384d3 | bellard | |
147 | 5fafdf24 | ths | static int cow_is_allocated(BlockDriverState *bs, int64_t sector_num, |
148 | ea2384d3 | bellard | int nb_sectors, int *pnum) |
149 | ea2384d3 | bellard | { |
150 | ea2384d3 | bellard | BDRVCowState *s = bs->opaque; |
151 | ea2384d3 | bellard | return is_changed(s->cow_bitmap, sector_num, nb_sectors, pnum);
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152 | ea2384d3 | bellard | } |
153 | ea2384d3 | bellard | |
154 | 5fafdf24 | ths | static int cow_read(BlockDriverState *bs, int64_t sector_num, |
155 | ea2384d3 | bellard | uint8_t *buf, int nb_sectors)
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156 | ea2384d3 | bellard | { |
157 | ea2384d3 | bellard | BDRVCowState *s = bs->opaque; |
158 | ea2384d3 | bellard | int ret, n;
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159 | 3b46e624 | ths | |
160 | ea2384d3 | bellard | while (nb_sectors > 0) { |
161 | ea2384d3 | bellard | if (is_changed(s->cow_bitmap, sector_num, nb_sectors, &n)) {
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162 | d5249393 | bellard | lseek(s->fd, s->cow_sectors_offset + sector_num * 512, SEEK_SET);
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163 | ea2384d3 | bellard | ret = read(s->fd, buf, n * 512);
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164 | 5fafdf24 | ths | if (ret != n * 512) |
165 | ea2384d3 | bellard | return -1; |
166 | ea2384d3 | bellard | } else {
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167 | 83f64091 | bellard | if (bs->backing_hd) {
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168 | 83f64091 | bellard | /* read from the base image */
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169 | 83f64091 | bellard | ret = bdrv_read(bs->backing_hd, sector_num, buf, n); |
170 | 83f64091 | bellard | if (ret < 0) |
171 | 83f64091 | bellard | return -1; |
172 | 83f64091 | bellard | } else {
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173 | ea2384d3 | bellard | memset(buf, 0, n * 512); |
174 | ea2384d3 | bellard | } |
175 | 83f64091 | bellard | } |
176 | ea2384d3 | bellard | nb_sectors -= n; |
177 | ea2384d3 | bellard | sector_num += n; |
178 | ea2384d3 | bellard | buf += n * 512;
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179 | ea2384d3 | bellard | } |
180 | ea2384d3 | bellard | return 0; |
181 | ea2384d3 | bellard | } |
182 | ea2384d3 | bellard | |
183 | 5fafdf24 | ths | static int cow_write(BlockDriverState *bs, int64_t sector_num, |
184 | ea2384d3 | bellard | const uint8_t *buf, int nb_sectors) |
185 | ea2384d3 | bellard | { |
186 | ea2384d3 | bellard | BDRVCowState *s = bs->opaque; |
187 | ea2384d3 | bellard | int ret, i;
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188 | 3b46e624 | ths | |
189 | d5249393 | bellard | lseek(s->fd, s->cow_sectors_offset + sector_num * 512, SEEK_SET);
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190 | ea2384d3 | bellard | ret = write(s->fd, buf, nb_sectors * 512);
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191 | 5fafdf24 | ths | if (ret != nb_sectors * 512) |
192 | ea2384d3 | bellard | return -1; |
193 | ea2384d3 | bellard | for (i = 0; i < nb_sectors; i++) |
194 | 2b03a7a5 | bellard | cow_set_bit(s->cow_bitmap, sector_num + i); |
195 | ea2384d3 | bellard | return 0; |
196 | ea2384d3 | bellard | } |
197 | ea2384d3 | bellard | |
198 | e2731add | bellard | static void cow_close(BlockDriverState *bs) |
199 | ea2384d3 | bellard | { |
200 | ea2384d3 | bellard | BDRVCowState *s = bs->opaque; |
201 | 3f4cb3d3 | blueswir1 | munmap((void *)s->cow_bitmap_addr, s->cow_bitmap_size);
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202 | ea2384d3 | bellard | close(s->fd); |
203 | ea2384d3 | bellard | } |
204 | ea2384d3 | bellard | |
205 | 0e7e1989 | Kevin Wolf | static int cow_create(const char *filename, QEMUOptionParameter *options) |
206 | ea2384d3 | bellard | { |
207 | ea2384d3 | bellard | int fd, cow_fd;
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208 | ea2384d3 | bellard | struct cow_header_v2 cow_header;
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209 | ea2384d3 | bellard | struct stat st;
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210 | 0e7e1989 | Kevin Wolf | int64_t image_sectors = 0;
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211 | 0e7e1989 | Kevin Wolf | const char *image_filename = NULL; |
212 | 31f38120 | Kirill A. Shutemov | int ret;
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213 | 0e7e1989 | Kevin Wolf | |
214 | 0e7e1989 | Kevin Wolf | /* Read out options */
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215 | 0e7e1989 | Kevin Wolf | while (options && options->name) {
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216 | 0e7e1989 | Kevin Wolf | if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
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217 | 0e7e1989 | Kevin Wolf | image_sectors = options->value.n / 512;
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218 | 0e7e1989 | Kevin Wolf | } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FILE)) { |
219 | 0e7e1989 | Kevin Wolf | image_filename = options->value.s; |
220 | 0e7e1989 | Kevin Wolf | } |
221 | 0e7e1989 | Kevin Wolf | options++; |
222 | 0e7e1989 | Kevin Wolf | } |
223 | ea2384d3 | bellard | |
224 | 5fafdf24 | ths | cow_fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, |
225 | ea2384d3 | bellard | 0644);
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226 | ea2384d3 | bellard | if (cow_fd < 0) |
227 | 48b66db9 | Juan Quintela | return -errno;
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228 | ea2384d3 | bellard | memset(&cow_header, 0, sizeof(cow_header)); |
229 | ea2384d3 | bellard | cow_header.magic = cpu_to_be32(COW_MAGIC); |
230 | ea2384d3 | bellard | cow_header.version = cpu_to_be32(COW_VERSION); |
231 | ea2384d3 | bellard | if (image_filename) {
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232 | 83f64091 | bellard | /* Note: if no file, we put a dummy mtime */
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233 | 83f64091 | bellard | cow_header.mtime = cpu_to_be32(0);
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234 | 83f64091 | bellard | |
235 | ea2384d3 | bellard | fd = open(image_filename, O_RDONLY | O_BINARY); |
236 | ea2384d3 | bellard | if (fd < 0) { |
237 | ea2384d3 | bellard | close(cow_fd); |
238 | 83f64091 | bellard | goto mtime_fail;
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239 | ea2384d3 | bellard | } |
240 | ea2384d3 | bellard | if (fstat(fd, &st) != 0) { |
241 | ea2384d3 | bellard | close(fd); |
242 | 83f64091 | bellard | goto mtime_fail;
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243 | ea2384d3 | bellard | } |
244 | ea2384d3 | bellard | close(fd); |
245 | ea2384d3 | bellard | cow_header.mtime = cpu_to_be32(st.st_mtime); |
246 | 83f64091 | bellard | mtime_fail:
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247 | 83f64091 | bellard | pstrcpy(cow_header.backing_file, sizeof(cow_header.backing_file),
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248 | 83f64091 | bellard | image_filename); |
249 | ea2384d3 | bellard | } |
250 | ea2384d3 | bellard | cow_header.sectorsize = cpu_to_be32(512);
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251 | ea2384d3 | bellard | cow_header.size = cpu_to_be64(image_sectors * 512);
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252 | 31f38120 | Kirill A. Shutemov | ret = qemu_write_full(cow_fd, &cow_header, sizeof(cow_header));
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253 | 31f38120 | Kirill A. Shutemov | if (ret != sizeof(cow_header)) { |
254 | 48b66db9 | Juan Quintela | ret = -errno; |
255 | 31f38120 | Kirill A. Shutemov | goto exit;
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256 | 31f38120 | Kirill A. Shutemov | } |
257 | 31f38120 | Kirill A. Shutemov | |
258 | ea2384d3 | bellard | /* resize to include at least all the bitmap */
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259 | 31f38120 | Kirill A. Shutemov | ret = ftruncate(cow_fd, sizeof(cow_header) + ((image_sectors + 7) >> 3)); |
260 | 31f38120 | Kirill A. Shutemov | if (ret) {
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261 | 31f38120 | Kirill A. Shutemov | ret = -errno; |
262 | 31f38120 | Kirill A. Shutemov | goto exit;
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263 | 31f38120 | Kirill A. Shutemov | } |
264 | 31f38120 | Kirill A. Shutemov | |
265 | 31f38120 | Kirill A. Shutemov | exit:
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266 | ea2384d3 | bellard | close(cow_fd); |
267 | 31f38120 | Kirill A. Shutemov | return ret;
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268 | ea2384d3 | bellard | } |
269 | ea2384d3 | bellard | |
270 | 7a6cba61 | pbrook | static void cow_flush(BlockDriverState *bs) |
271 | 7a6cba61 | pbrook | { |
272 | 7a6cba61 | pbrook | BDRVCowState *s = bs->opaque; |
273 | 6f1953c4 | Christoph Hellwig | qemu_fdatasync(s->fd); |
274 | 7a6cba61 | pbrook | } |
275 | 7a6cba61 | pbrook | |
276 | 0e7e1989 | Kevin Wolf | static QEMUOptionParameter cow_create_options[] = {
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277 | db08adf5 | Kevin Wolf | { |
278 | db08adf5 | Kevin Wolf | .name = BLOCK_OPT_SIZE, |
279 | db08adf5 | Kevin Wolf | .type = OPT_SIZE, |
280 | db08adf5 | Kevin Wolf | .help = "Virtual disk size"
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281 | db08adf5 | Kevin Wolf | }, |
282 | db08adf5 | Kevin Wolf | { |
283 | db08adf5 | Kevin Wolf | .name = BLOCK_OPT_BACKING_FILE, |
284 | db08adf5 | Kevin Wolf | .type = OPT_STRING, |
285 | db08adf5 | Kevin Wolf | .help = "File name of a base image"
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286 | db08adf5 | Kevin Wolf | }, |
287 | 0e7e1989 | Kevin Wolf | { NULL }
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288 | 0e7e1989 | Kevin Wolf | }; |
289 | 0e7e1989 | Kevin Wolf | |
290 | 5efa9d5a | Anthony Liguori | static BlockDriver bdrv_cow = {
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291 | e60f469c | aurel32 | .format_name = "cow",
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292 | e60f469c | aurel32 | .instance_size = sizeof(BDRVCowState),
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293 | e60f469c | aurel32 | .bdrv_probe = cow_probe, |
294 | e60f469c | aurel32 | .bdrv_open = cow_open, |
295 | e60f469c | aurel32 | .bdrv_read = cow_read, |
296 | e60f469c | aurel32 | .bdrv_write = cow_write, |
297 | e60f469c | aurel32 | .bdrv_close = cow_close, |
298 | e60f469c | aurel32 | .bdrv_create = cow_create, |
299 | e60f469c | aurel32 | .bdrv_flush = cow_flush, |
300 | e60f469c | aurel32 | .bdrv_is_allocated = cow_is_allocated, |
301 | 0e7e1989 | Kevin Wolf | |
302 | 0e7e1989 | Kevin Wolf | .create_options = cow_create_options, |
303 | ea2384d3 | bellard | }; |
304 | 5efa9d5a | Anthony Liguori | |
305 | 5efa9d5a | Anthony Liguori | static void bdrv_cow_init(void) |
306 | 5efa9d5a | Anthony Liguori | { |
307 | 5efa9d5a | Anthony Liguori | bdrv_register(&bdrv_cow); |
308 | 5efa9d5a | Anthony Liguori | } |
309 | 5efa9d5a | Anthony Liguori | |
310 | 5efa9d5a | Anthony Liguori | block_init(bdrv_cow_init); |
311 | ea2384d3 | bellard | #endif |