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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/um/drivers/cow_user.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/um/drivers/cow_user.c')
-rw-r--r--arch/um/drivers/cow_user.c378
1 files changed, 378 insertions, 0 deletions
diff --git a/arch/um/drivers/cow_user.c b/arch/um/drivers/cow_user.c
new file mode 100644
index 000000000000..a8ce6fc3ef26
--- /dev/null
+++ b/arch/um/drivers/cow_user.c
@@ -0,0 +1,378 @@
1#include <stddef.h>
2#include <string.h>
3#include <errno.h>
4/* _XOPEN_SOURCE is needed for pread, but we define _GNU_SOURCE, which defines
5 * that.
6 */
7#include <unistd.h>
8#include <byteswap.h>
9#include <sys/time.h>
10#include <sys/param.h>
11#include <sys/user.h>
12#include <netinet/in.h>
13
14#include "os.h"
15
16#include "cow.h"
17#include "cow_sys.h"
18
19#define PATH_LEN_V1 256
20
21struct cow_header_v1 {
22 int magic;
23 int version;
24 char backing_file[PATH_LEN_V1];
25 time_t mtime;
26 __u64 size;
27 int sectorsize;
28};
29
30#define PATH_LEN_V2 MAXPATHLEN
31
32struct cow_header_v2 {
33 __u32 magic;
34 __u32 version;
35 char backing_file[PATH_LEN_V2];
36 time_t mtime;
37 __u64 size;
38 int sectorsize;
39};
40
41/* Define PATH_LEN_V3 as the usual value of MAXPATHLEN, just hard-code it in
42 * case other systems have different values for MAXPATHLEN
43 */
44#define PATH_LEN_V3 4096
45
46/* Changes from V2 -
47 * PATH_LEN_V3 as described above
48 * Explicitly specify field bit lengths for systems with different
49 * lengths for the usual C types. Not sure whether char or
50 * time_t should be changed, this can be changed later without
51 * breaking compatibility
52 * Add alignment field so that different alignments can be used for the
53 * bitmap and data
54 * Add cow_format field to allow for the possibility of different ways
55 * of specifying the COW blocks. For now, the only value is 0,
56 * for the traditional COW bitmap.
57 * Move the backing_file field to the end of the header. This allows
58 * for the possibility of expanding it into the padding required
59 * by the bitmap alignment.
60 * The bitmap and data portions of the file will be aligned as specified
61 * by the alignment field. This is to allow COW files to be
62 * put on devices with restrictions on access alignments, such as
63 * /dev/raw, with a 512 byte alignment restriction. This also
64 * allows the data to be more aligned more strictly than on
65 * sector boundaries. This is needed for ubd-mmap, which needs
66 * the data to be page aligned.
67 * Fixed (finally!) the rounding bug
68 */
69
70struct cow_header_v3 {
71 __u32 magic;
72 __u32 version;
73 __u32 mtime;
74 __u64 size;
75 __u32 sectorsize;
76 __u32 alignment;
77 __u32 cow_format;
78 char backing_file[PATH_LEN_V3];
79};
80
81/* COW format definitions - for now, we have only the usual COW bitmap */
82#define COW_BITMAP 0
83
84union cow_header {
85 struct cow_header_v1 v1;
86 struct cow_header_v2 v2;
87 struct cow_header_v3 v3;
88};
89
90#define COW_MAGIC 0x4f4f4f4d /* MOOO */
91#define COW_VERSION 3
92
93#define DIV_ROUND(x, len) (((x) + (len) - 1) / (len))
94#define ROUND_UP(x, align) DIV_ROUND(x, align) * (align)
95
96void cow_sizes(int version, __u64 size, int sectorsize, int align,
97 int bitmap_offset, unsigned long *bitmap_len_out,
98 int *data_offset_out)
99{
100 if(version < 3){
101 *bitmap_len_out = (size + sectorsize - 1) / (8 * sectorsize);
102
103 *data_offset_out = bitmap_offset + *bitmap_len_out;
104 *data_offset_out = (*data_offset_out + sectorsize - 1) /
105 sectorsize;
106 *data_offset_out *= sectorsize;
107 }
108 else {
109 *bitmap_len_out = DIV_ROUND(size, sectorsize);
110 *bitmap_len_out = DIV_ROUND(*bitmap_len_out, 8);
111
112 *data_offset_out = bitmap_offset + *bitmap_len_out;
113 *data_offset_out = ROUND_UP(*data_offset_out, align);
114 }
115}
116
117static int absolutize(char *to, int size, char *from)
118{
119 char save_cwd[256], *slash;
120 int remaining;
121
122 if(getcwd(save_cwd, sizeof(save_cwd)) == NULL) {
123 cow_printf("absolutize : unable to get cwd - errno = %d\n",
124 errno);
125 return(-1);
126 }
127 slash = strrchr(from, '/');
128 if(slash != NULL){
129 *slash = '\0';
130 if(chdir(from)){
131 *slash = '/';
132 cow_printf("absolutize : Can't cd to '%s' - "
133 "errno = %d\n", from, errno);
134 return(-1);
135 }
136 *slash = '/';
137 if(getcwd(to, size) == NULL){
138 cow_printf("absolutize : unable to get cwd of '%s' - "
139 "errno = %d\n", from, errno);
140 return(-1);
141 }
142 remaining = size - strlen(to);
143 if(strlen(slash) + 1 > remaining){
144 cow_printf("absolutize : unable to fit '%s' into %d "
145 "chars\n", from, size);
146 return(-1);
147 }
148 strcat(to, slash);
149 }
150 else {
151 if(strlen(save_cwd) + 1 + strlen(from) + 1 > size){
152 cow_printf("absolutize : unable to fit '%s' into %d "
153 "chars\n", from, size);
154 return(-1);
155 }
156 strcpy(to, save_cwd);
157 strcat(to, "/");
158 strcat(to, from);
159 }
160 chdir(save_cwd);
161 return(0);
162}
163
164int write_cow_header(char *cow_file, int fd, char *backing_file,
165 int sectorsize, int alignment, unsigned long long *size)
166{
167 struct cow_header_v3 *header;
168 unsigned long modtime;
169 int err;
170
171 err = cow_seek_file(fd, 0);
172 if(err < 0){
173 cow_printf("write_cow_header - lseek failed, err = %d\n", -err);
174 goto out;
175 }
176
177 err = -ENOMEM;
178 header = cow_malloc(sizeof(*header));
179 if(header == NULL){
180 cow_printf("Failed to allocate COW V3 header\n");
181 goto out;
182 }
183 header->magic = htonl(COW_MAGIC);
184 header->version = htonl(COW_VERSION);
185
186 err = -EINVAL;
187 if(strlen(backing_file) > sizeof(header->backing_file) - 1){
188 cow_printf("Backing file name \"%s\" is too long - names are "
189 "limited to %d characters\n", backing_file,
190 sizeof(header->backing_file) - 1);
191 goto out_free;
192 }
193
194 if(absolutize(header->backing_file, sizeof(header->backing_file),
195 backing_file))
196 goto out_free;
197
198 err = os_file_modtime(header->backing_file, &modtime);
199 if(err < 0){
200 cow_printf("Backing file '%s' mtime request failed, "
201 "err = %d\n", header->backing_file, -err);
202 goto out_free;
203 }
204
205 err = cow_file_size(header->backing_file, size);
206 if(err < 0){
207 cow_printf("Couldn't get size of backing file '%s', "
208 "err = %d\n", header->backing_file, -err);
209 goto out_free;
210 }
211
212 header->mtime = htonl(modtime);
213 header->size = htonll(*size);
214 header->sectorsize = htonl(sectorsize);
215 header->alignment = htonl(alignment);
216 header->cow_format = COW_BITMAP;
217
218 err = os_write_file(fd, header, sizeof(*header));
219 if(err != sizeof(*header)){
220 cow_printf("Write of header to new COW file '%s' failed, "
221 "err = %d\n", cow_file, -err);
222 goto out_free;
223 }
224 err = 0;
225 out_free:
226 cow_free(header);
227 out:
228 return(err);
229}
230
231int file_reader(__u64 offset, char *buf, int len, void *arg)
232{
233 int fd = *((int *) arg);
234
235 return(pread(fd, buf, len, offset));
236}
237
238/* XXX Need to sanity-check the values read from the header */
239
240int read_cow_header(int (*reader)(__u64, char *, int, void *), void *arg,
241 __u32 *version_out, char **backing_file_out,
242 time_t *mtime_out, unsigned long long *size_out,
243 int *sectorsize_out, __u32 *align_out,
244 int *bitmap_offset_out)
245{
246 union cow_header *header;
247 char *file;
248 int err, n;
249 unsigned long version, magic;
250
251 header = cow_malloc(sizeof(*header));
252 if(header == NULL){
253 cow_printf("read_cow_header - Failed to allocate header\n");
254 return(-ENOMEM);
255 }
256 err = -EINVAL;
257 n = (*reader)(0, (char *) header, sizeof(*header), arg);
258 if(n < offsetof(typeof(header->v1), backing_file)){
259 cow_printf("read_cow_header - short header\n");
260 goto out;
261 }
262
263 magic = header->v1.magic;
264 if(magic == COW_MAGIC) {
265 version = header->v1.version;
266 }
267 else if(magic == ntohl(COW_MAGIC)){
268 version = ntohl(header->v1.version);
269 }
270 /* No error printed because the non-COW case comes through here */
271 else goto out;
272
273 *version_out = version;
274
275 if(version == 1){
276 if(n < sizeof(header->v1)){
277 cow_printf("read_cow_header - failed to read V1 "
278 "header\n");
279 goto out;
280 }
281 *mtime_out = header->v1.mtime;
282 *size_out = header->v1.size;
283 *sectorsize_out = header->v1.sectorsize;
284 *bitmap_offset_out = sizeof(header->v1);
285 *align_out = *sectorsize_out;
286 file = header->v1.backing_file;
287 }
288 else if(version == 2){
289 if(n < sizeof(header->v2)){
290 cow_printf("read_cow_header - failed to read V2 "
291 "header\n");
292 goto out;
293 }
294 *mtime_out = ntohl(header->v2.mtime);
295 *size_out = ntohll(header->v2.size);
296 *sectorsize_out = ntohl(header->v2.sectorsize);
297 *bitmap_offset_out = sizeof(header->v2);
298 *align_out = *sectorsize_out;
299 file = header->v2.backing_file;
300 }
301 else if(version == 3){
302 if(n < sizeof(header->v3)){
303 cow_printf("read_cow_header - failed to read V2 "
304 "header\n");
305 goto out;
306 }
307 *mtime_out = ntohl(header->v3.mtime);
308 *size_out = ntohll(header->v3.size);
309 *sectorsize_out = ntohl(header->v3.sectorsize);
310 *align_out = ntohl(header->v3.alignment);
311 *bitmap_offset_out = ROUND_UP(sizeof(header->v3), *align_out);
312 file = header->v3.backing_file;
313 }
314 else {
315 cow_printf("read_cow_header - invalid COW version\n");
316 goto out;
317 }
318 err = -ENOMEM;
319 *backing_file_out = cow_strdup(file);
320 if(*backing_file_out == NULL){
321 cow_printf("read_cow_header - failed to allocate backing "
322 "file\n");
323 goto out;
324 }
325 err = 0;
326 out:
327 cow_free(header);
328 return(err);
329}
330
331int init_cow_file(int fd, char *cow_file, char *backing_file, int sectorsize,
332 int alignment, int *bitmap_offset_out,
333 unsigned long *bitmap_len_out, int *data_offset_out)
334{
335 unsigned long long size, offset;
336 char zero = 0;
337 int err;
338
339 err = write_cow_header(cow_file, fd, backing_file, sectorsize,
340 alignment, &size);
341 if(err)
342 goto out;
343
344 *bitmap_offset_out = ROUND_UP(sizeof(struct cow_header_v3), alignment);
345 cow_sizes(COW_VERSION, size, sectorsize, alignment, *bitmap_offset_out,
346 bitmap_len_out, data_offset_out);
347
348 offset = *data_offset_out + size - sizeof(zero);
349 err = cow_seek_file(fd, offset);
350 if(err < 0){
351 cow_printf("cow bitmap lseek failed : err = %d\n", -err);
352 goto out;
353 }
354
355 /* does not really matter how much we write it is just to set EOF
356 * this also sets the entire COW bitmap
357 * to zero without having to allocate it
358 */
359 err = cow_write_file(fd, &zero, sizeof(zero));
360 if(err != sizeof(zero)){
361 cow_printf("Write of bitmap to new COW file '%s' failed, "
362 "err = %d\n", cow_file, -err);
363 err = -EINVAL;
364 goto out;
365 }
366
367 return(0);
368
369 out:
370 return(err);
371}
372
373/*
374 * ---------------------------------------------------------------------------
375 * Local variables:
376 * c-file-style: "linux"
377 * End:
378 */