[linux-2.6-block.git] / arch / um / drivers / cow_user.c

#include <stddef.h>
#include <string.h>
#include <errno.h>
/* _XOPEN_SOURCE is needed for pread, but we define _GNU_SOURCE, which defines
 * that.
 */
#include <unistd.h>
#include <byteswap.h>
#include <sys/time.h>
#include <sys/param.h>
#include <sys/user.h>

#include "os.h"

#include "cow.h"
#include "cow_sys.h"

#define PATH_LEN_V1 256

struct cow_header_v1 {
	int magic;
	int version;
	char backing_file[PATH_LEN_V1];
	time_t mtime;
	__u64 size;
	int sectorsize;
};

#define PATH_LEN_V2 MAXPATHLEN

struct cow_header_v2 {
	__u32 magic;
	__u32 version;
	char backing_file[PATH_LEN_V2];
	time_t mtime;
	__u64 size;
	int sectorsize;
};

/* Define PATH_LEN_V3 as the usual value of MAXPATHLEN, just hard-code it in
 * case other systems have different values for MAXPATHLEN
 */
#define PATH_LEN_V3 4096

/* Changes from V2 -
 *	PATH_LEN_V3 as described above
 *	Explicitly specify field bit lengths for systems with different
 *		lengths for the usual C types.  Not sure whether char or
 *		time_t should be changed, this can be changed later without
 *		breaking compatibility
 *	Add alignment field so that different alignments can be used for the
 *		bitmap and data
 * 	Add cow_format field to allow for the possibility of different ways
 *		of specifying the COW blocks.  For now, the only value is 0,
 * 		for the traditional COW bitmap.
 *	Move the backing_file field to the end of the header.  This allows
 *		for the possibility of expanding it into the padding required
 *		by the bitmap alignment.
 * 	The bitmap and data portions of the file will be aligned as specified
 * 		by the alignment field.  This is to allow COW files to be
 *		put on devices with restrictions on access alignments, such as
 *		/dev/raw, with a 512 byte alignment restriction.  This also
 *		allows the data to be more aligned more strictly than on
 *		sector boundaries.  This is needed for ubd-mmap, which needs
 *		the data to be page aligned.
 *	Fixed (finally!) the rounding bug
 */

struct cow_header_v3 {
	__u32 magic;
	__u32 version;
	__u32 mtime;
	__u64 size;
	__u32 sectorsize;
	__u32 alignment;
	__u32 cow_format;
	char backing_file[PATH_LEN_V3];
};

/* COW format definitions - for now, we have only the usual COW bitmap */
#define COW_BITMAP 0

union cow_header {
	struct cow_header_v1 v1;
	struct cow_header_v2 v2;
	struct cow_header_v3 v3;
};

#define COW_MAGIC 0x4f4f4f4d  /* MOOO */
#define COW_VERSION 3

#define DIV_ROUND(x, len) (((x) + (len) - 1) / (len))
#define ROUND_UP(x, align) DIV_ROUND(x, align) * (align)

void cow_sizes(int version, __u64 size, int sectorsize, int align,
	       int bitmap_offset, unsigned long *bitmap_len_out,
	       int *data_offset_out)
{
	if(version < 3){
		*bitmap_len_out = (size + sectorsize - 1) / (8 * sectorsize);

		*data_offset_out = bitmap_offset + *bitmap_len_out;
		*data_offset_out = (*data_offset_out + sectorsize - 1) /
			sectorsize;
		*data_offset_out *= sectorsize;
	}
	else {
		*bitmap_len_out = DIV_ROUND(size, sectorsize);
		*bitmap_len_out = DIV_ROUND(*bitmap_len_out, 8);

		*data_offset_out = bitmap_offset + *bitmap_len_out;
		*data_offset_out = ROUND_UP(*data_offset_out, align);
	}
}

static int absolutize(char *to, int size, char *from)
{
	char save_cwd[256], *slash;
	int remaining;

	if(getcwd(save_cwd, sizeof(save_cwd)) == NULL) {
		cow_printf("absolutize : unable to get cwd - errno = %d\n",
			   errno);
		return(-1);
	}
	slash = strrchr(from, '/');
	if(slash != NULL){
		*slash = '\0';
		if(chdir(from)){
			*slash = '/';
			cow_printf("absolutize : Can't cd to '%s' - "
				   "errno = %d\n", from, errno);
			return(-1);
		}
		*slash = '/';
		if(getcwd(to, size) == NULL){
			cow_printf("absolutize : unable to get cwd of '%s' - "
			       "errno = %d\n", from, errno);
			return(-1);
		}
		remaining = size - strlen(to);
		if(strlen(slash) + 1 > remaining){
			cow_printf("absolutize : unable to fit '%s' into %d "
			       "chars\n", from, size);
			return(-1);
		}
		strcat(to, slash);
	}
	else {
		if(strlen(save_cwd) + 1 + strlen(from) + 1 > size){
			cow_printf("absolutize : unable to fit '%s' into %d "
			       "chars\n", from, size);
			return(-1);
		}
		strcpy(to, save_cwd);
		strcat(to, "/");
		strcat(to, from);
	}
	chdir(save_cwd);
	return(0);
}

int write_cow_header(char *cow_file, int fd, char *backing_file,
		     int sectorsize, int alignment, unsigned long long *size)
{
	struct cow_header_v3 *header;
	unsigned long modtime;
	int err;

	err = cow_seek_file(fd, 0);
	if(err < 0){
		cow_printf("write_cow_header - lseek failed, err = %d\n", -err);
		goto out;
	}

	err = -ENOMEM;
	header = cow_malloc(sizeof(*header));
	if(header == NULL){
		cow_printf("Failed to allocate COW V3 header\n");
		goto out;
	}
	header->magic = htonl(COW_MAGIC);
	header->version = htonl(COW_VERSION);

	err = -EINVAL;
	if(strlen(backing_file) > sizeof(header->backing_file) - 1){
		cow_printf("Backing file name \"%s\" is too long - names are "
			   "limited to %d characters\n", backing_file,
			   sizeof(header->backing_file) - 1);
		goto out_free;
	}

	if(absolutize(header->backing_file, sizeof(header->backing_file),
		      backing_file))
		goto out_free;

	err = os_file_modtime(header->backing_file, &modtime);
	if(err < 0){
		cow_printf("Backing file '%s' mtime request failed, "
			   "err = %d\n", header->backing_file, -err);
		goto out_free;
	}

	err = cow_file_size(header->backing_file, size);
	if(err < 0){
		cow_printf("Couldn't get size of backing file '%s', "
			   "err = %d\n", header->backing_file, -err);
		goto out_free;
	}

	header->mtime = htonl(modtime);
	header->size = htonll(*size);
	header->sectorsize = htonl(sectorsize);
	header->alignment = htonl(alignment);
	header->cow_format = COW_BITMAP;

	err = os_write_file(fd, header, sizeof(*header));
	if(err != sizeof(*header)){
		cow_printf("Write of header to new COW file '%s' failed, "
			   "err = %d\n", cow_file, -err);
		goto out_free;
	}
	err = 0;
 out_free:
	cow_free(header);
 out:
	return(err);
}

int file_reader(__u64 offset, char *buf, int len, void *arg)
{
	int fd = *((int *) arg);

	return(pread(fd, buf, len, offset));
}

/* XXX Need to sanity-check the values read from the header */

int read_cow_header(int (*reader)(__u64, char *, int, void *), void *arg,
		    __u32 *version_out, char **backing_file_out,
		    time_t *mtime_out, unsigned long long *size_out,
		    int *sectorsize_out, __u32 *align_out,
		    int *bitmap_offset_out)
{
	union cow_header *header;
	char *file;
	int err, n;
	unsigned long version, magic;

	header = cow_malloc(sizeof(*header));
	if(header == NULL){
	        cow_printf("read_cow_header - Failed to allocate header\n");
		return(-ENOMEM);
	}
	err = -EINVAL;
	n = (*reader)(0, (char *) header, sizeof(*header), arg);
	if(n < offsetof(typeof(header->v1), backing_file)){
		cow_printf("read_cow_header - short header\n");
		goto out;
	}

	magic = header->v1.magic;
	if(magic == COW_MAGIC) {
		version = header->v1.version;
	}
	else if(magic == ntohl(COW_MAGIC)){
		version = ntohl(header->v1.version);
	}
	/* No error printed because the non-COW case comes through here */
	else goto out;

	*version_out = version;

	if(version == 1){
		if(n < sizeof(header->v1)){
			cow_printf("read_cow_header - failed to read V1 "
				   "header\n");
			goto out;
		}
		*mtime_out = header->v1.mtime;
		*size_out = header->v1.size;
		*sectorsize_out = header->v1.sectorsize;
		*bitmap_offset_out = sizeof(header->v1);
		*align_out = *sectorsize_out;
		file = header->v1.backing_file;
	}
	else if(version == 2){
		if(n < sizeof(header->v2)){
			cow_printf("read_cow_header - failed to read V2 "
				   "header\n");
			goto out;
		}
		*mtime_out = ntohl(header->v2.mtime);
		*size_out = ntohll(header->v2.size);
		*sectorsize_out = ntohl(header->v2.sectorsize);
		*bitmap_offset_out = sizeof(header->v2);
		*align_out = *sectorsize_out;
		file = header->v2.backing_file;
	}
	else if(version == 3){
		if(n < sizeof(header->v3)){
			cow_printf("read_cow_header - failed to read V2 "
				   "header\n");
			goto out;
		}
		*mtime_out = ntohl(header->v3.mtime);
		*size_out = ntohll(header->v3.size);
		*sectorsize_out = ntohl(header->v3.sectorsize);
		*align_out = ntohl(header->v3.alignment);
		*bitmap_offset_out = ROUND_UP(sizeof(header->v3), *align_out);
		file = header->v3.backing_file;
	}
	else {
		cow_printf("read_cow_header - invalid COW version\n");
		goto out;
	}
	err = -ENOMEM;
	*backing_file_out = cow_strdup(file);
	if(*backing_file_out == NULL){
		cow_printf("read_cow_header - failed to allocate backing "
			   "file\n");
		goto out;
	}
	err = 0;
 out:
	cow_free(header);
	return(err);
}

int init_cow_file(int fd, char *cow_file, char *backing_file, int sectorsize,
		  int alignment, int *bitmap_offset_out,
		  unsigned long *bitmap_len_out, int *data_offset_out)
{
	unsigned long long size, offset;
	char zero = 0;
	int err;

	err = write_cow_header(cow_file, fd, backing_file, sectorsize,
			       alignment, &size);
	if(err)
		goto out;

	*bitmap_offset_out = ROUND_UP(sizeof(struct cow_header_v3), alignment);
	cow_sizes(COW_VERSION, size, sectorsize, alignment, *bitmap_offset_out,
		  bitmap_len_out, data_offset_out);

	offset = *data_offset_out + size - sizeof(zero);
	err = cow_seek_file(fd, offset);
	if(err < 0){
		cow_printf("cow bitmap lseek failed : err = %d\n", -err);
		goto out;
	}

	/* does not really matter how much we write it is just to set EOF
	 * this also sets the entire COW bitmap
	 * to zero without having to allocate it
	 */
	err = cow_write_file(fd, &zero, sizeof(zero));
	if(err != sizeof(zero)){
		cow_printf("Write of bitmap to new COW file '%s' failed, "
			   "err = %d\n", cow_file, -err);
		err = -EINVAL;
		goto out;
	}

	return(0);

 out:
	return(err);
}

/*
 * ---------------------------------------------------------------------------
 * Local variables:
 * c-file-style: "linux"
 * End:
 */
Commit	Line	Data
1da177e4 LT	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>
1da177e4 LT	12
	13	#include "os.h"
	14
	15	#include "cow.h"
	16	#include "cow_sys.h"
	17
	18	#define PATH_LEN_V1 256
	19
	20	struct cow_header_v1 {
	21	int magic;
	22	int version;
	23	char backing_file[PATH_LEN_V1];
	24	time_t mtime;
	25	__u64 size;
	26	int sectorsize;
	27	};
	28
	29	#define PATH_LEN_V2 MAXPATHLEN
	30
	31	struct cow_header_v2 {
	32	__u32 magic;
	33	__u32 version;
	34	char backing_file[PATH_LEN_V2];
	35	time_t mtime;
	36	__u64 size;
	37	int sectorsize;
	38	};
	39
	40	/* Define PATH_LEN_V3 as the usual value of MAXPATHLEN, just hard-code it in
	41	* case other systems have different values for MAXPATHLEN
	42	*/
	43	#define PATH_LEN_V3 4096
	44
	45	/* Changes from V2 -
	46	* PATH_LEN_V3 as described above
	47	* Explicitly specify field bit lengths for systems with different
	48	* lengths for the usual C types. Not sure whether char or
	49	* time_t should be changed, this can be changed later without
	50	* breaking compatibility
	51	* Add alignment field so that different alignments can be used for the
	52	* bitmap and data
	53	* Add cow_format field to allow for the possibility of different ways
	54	* of specifying the COW blocks. For now, the only value is 0,
	55	* for the traditional COW bitmap.
	56	* Move the backing_file field to the end of the header. This allows
	57	* for the possibility of expanding it into the padding required
	58	* by the bitmap alignment.
	59	* The bitmap and data portions of the file will be aligned as specified
	60	* by the alignment field. This is to allow COW files to be
	61	* put on devices with restrictions on access alignments, such as
	62	* /dev/raw, with a 512 byte alignment restriction. This also
	63	* allows the data to be more aligned more strictly than on
	64	* sector boundaries. This is needed for ubd-mmap, which needs
	65	* the data to be page aligned.
	66	* Fixed (finally!) the rounding bug
	67	*/
	68
	69	struct cow_header_v3 {
	70	__u32 magic;
	71	__u32 version;
	72	__u32 mtime;
	73	__u64 size;
	74	__u32 sectorsize;
	75	__u32 alignment;
76	__u32 cow_format;
77	char backing_file[PATH_LEN_V3];
78	};
79
80	/* COW format definitions - for now, we have only the usual COW bitmap */
81	#define COW_BITMAP 0
82
83	union cow_header {
84	struct cow_header_v1 v1;
85	struct cow_header_v2 v2;
86	struct cow_header_v3 v3;
87	};
88
89	#define COW_MAGIC 0x4f4f4f4d /* MOOO */
90	#define COW_VERSION 3
91
92	#define DIV_ROUND(x, len) (((x) + (len) - 1) / (len))
93	#define ROUND_UP(x, align) DIV_ROUND(x, align) * (align)
94
95	void cow_sizes(int version, __u64 size, int sectorsize, int align,
96	int bitmap_offset, unsigned long *bitmap_len_out,
97	int *data_offset_out)
98	{
99	if(version < 3){
100	bitmap_len_out = (size + sectorsize - 1) / (8 sectorsize);
101
102	data_offset_out = bitmap_offset + bitmap_len_out;
103	data_offset_out = (data_offset_out + sectorsize - 1) /
104	sectorsize;
105	data_offset_out = sectorsize;
106	}
107	else {
108	*bitmap_len_out = DIV_ROUND(size, sectorsize);
109	bitmap_len_out = DIV_ROUND(bitmap_len_out, 8);
110
111	data_offset_out = bitmap_offset + bitmap_len_out;
112	data_offset_out = ROUND_UP(data_offset_out, align);
113	}
114	}
115
116	static int absolutize(char to, int size, char from)
117	{
118	char save_cwd[256], *slash;
119	int remaining;
120
121	if(getcwd(save_cwd, sizeof(save_cwd)) == NULL) {
122	cow_printf("absolutize : unable to get cwd - errno = %d\n",
123	errno);
124	return(-1);
125	}
126	slash = strrchr(from, '/');
127	if(slash != NULL){
128	*slash = '\0';
129	if(chdir(from)){
130	*slash = '/';
131	cow_printf("absolutize : Can't cd to '%s' - "
132	"errno = %d\n", from, errno);
133	return(-1);
134	}
135	*slash = '/';
136	if(getcwd(to, size) == NULL){
137	cow_printf("absolutize : unable to get cwd of '%s' - "
138	"errno = %d\n", from, errno);
139	return(-1);
140	}
141	remaining = size - strlen(to);
142	if(strlen(slash) + 1 > remaining){
143	cow_printf("absolutize : unable to fit '%s' into %d "
144	"chars\n", from, size);
145	return(-1);
146	}
147	strcat(to, slash);
148	}
149	else {
150	if(strlen(save_cwd) + 1 + strlen(from) + 1 > size){
151	cow_printf("absolutize : unable to fit '%s' into %d "
152	"chars\n", from, size);
153	return(-1);
154	}
155	strcpy(to, save_cwd);
156	strcat(to, "/");
157	strcat(to, from);
158	}
159	chdir(save_cwd);
160	return(0);
161	}
162
163	int write_cow_header(char cow_file, int fd, char backing_file,
164	int sectorsize, int alignment, unsigned long long *size)
165	{
166	struct cow_header_v3 *header;
167	unsigned long modtime;
168	int err;
169
170	err = cow_seek_file(fd, 0);
171	if(err < 0){
172	cow_printf("write_cow_header - lseek failed, err = %d\n", -err);
173	goto out;
174	}
175
176	err = -ENOMEM;
177	header = cow_malloc(sizeof(*header));
178	if(header == NULL){
179	cow_printf("Failed to allocate COW V3 header\n");
180	goto out;
181	}
182	header->magic = htonl(COW_MAGIC);
183	header->version = htonl(COW_VERSION);
184
185	err = -EINVAL;
186	if(strlen(backing_file) > sizeof(header->backing_file) - 1){
187	cow_printf("Backing file name \"%s\" is too long - names are "
188	"limited to %d characters\n", backing_file,
189	sizeof(header->backing_file) - 1);
190	goto out_free;
191	}
192
193	if(absolutize(header->backing_file, sizeof(header->backing_file),
194	backing_file))
195	goto out_free;
196
197	err = os_file_modtime(header->backing_file, &modtime);
198	if(err < 0){
199	cow_printf("Backing file '%s' mtime request failed, "
200	"err = %d\n", header->backing_file, -err);
201	goto out_free;
202	}
203
204	err = cow_file_size(header->backing_file, size);
205	if(err < 0){
206	cow_printf("Couldn't get size of backing file '%s', "
207	"err = %d\n", header->backing_file, -err);
208	goto out_free;
209	}
210
211	header->mtime = htonl(modtime);
212	header->size = htonll(*size);
213	header->sectorsize = htonl(sectorsize);
214	header->alignment = htonl(alignment);
215	header->cow_format = COW_BITMAP;
216
217	err = os_write_file(fd, header, sizeof(*header));
218	if(err != sizeof(*header)){
219	cow_printf("Write of header to new COW file '%s' failed, "
220	"err = %d\n", cow_file, -err);
221	goto out_free;
222	}
223	err = 0;
224	out_free:
225	cow_free(header);
226	out:
227	return(err);
228	}
229
230	int file_reader(__u64 offset, char buf, int len, void arg)
231	{
232	int fd = ((int ) arg);
233
234	return(pread(fd, buf, len, offset));
235	}
236
237	/* XXX Need to sanity-check the values read from the header */
238
239	int read_cow_header(int (reader)(__u64, char , int, void ), void arg,
240	__u32 version_out, char *backing_file_out,
241	time_t mtime_out, unsigned long long size_out,
242	int sectorsize_out, __u32 align_out,
243	int *bitmap_offset_out)
244	{
245	union cow_header *header;
246	char *file;
247	int err, n;
248	unsigned long version, magic;
249
250	header = cow_malloc(sizeof(*header));
251	if(header == NULL){
252	cow_printf("read_cow_header - Failed to allocate header\n");
253	return(-ENOMEM);
254	}
255	err = -EINVAL;
256	n = (reader)(0, (char ) header, sizeof(*header), arg);
257	if(n < offsetof(typeof(header->v1), backing_file)){
258	cow_printf("read_cow_header - short header\n");
259	goto out;
260	}
261
262	magic = header->v1.magic;
263	if(magic == COW_MAGIC) {
264	version = header->v1.version;
265	}
266	else if(magic == ntohl(COW_MAGIC)){
267	version = ntohl(header->v1.version);
268	}
269	/* No error printed because the non-COW case comes through here */
270	else goto out;
271
272	*version_out = version;
273
274	if(version == 1){
275	if(n < sizeof(header->v1)){
276	cow_printf("read_cow_header - failed to read V1 "
277	"header\n");
278	goto out;
279	}
280	*mtime_out = header->v1.mtime;
281	*size_out = header->v1.size;
282	*sectorsize_out = header->v1.sectorsize;
283	*bitmap_offset_out = sizeof(header->v1);
284	align_out = sectorsize_out;
285	file = header->v1.backing_file;
286	}
287	else if(version == 2){
288	if(n < sizeof(header->v2)){
289	cow_printf("read_cow_header - failed to read V2 "
290	"header\n");
291	goto out;
292	}
293	*mtime_out = ntohl(header->v2.mtime);
294	*size_out = ntohll(header->v2.size);
295	*sectorsize_out = ntohl(header->v2.sectorsize);
296	*bitmap_offset_out = sizeof(header->v2);
297	align_out = sectorsize_out;
298	file = header->v2.backing_file;
299	}
300	else if(version == 3){
301	if(n < sizeof(header->v3)){
302	cow_printf("read_cow_header - failed to read V2 "
303	"header\n");
304	goto out;
305	}
306	*mtime_out = ntohl(header->v3.mtime);
307	*size_out = ntohll(header->v3.size);
308	*sectorsize_out = ntohl(header->v3.sectorsize);
309	*align_out = ntohl(header->v3.alignment);
310	bitmap_offset_out = ROUND_UP(sizeof(header->v3), align_out);
311	file = header->v3.backing_file;
312	}
313	else {
314	cow_printf("read_cow_header - invalid COW version\n");
315	goto out;
316	}
317	err = -ENOMEM;
318	*backing_file_out = cow_strdup(file);
319	if(*backing_file_out == NULL){
320	cow_printf("read_cow_header - failed to allocate backing "
321	"file\n");
322	goto out;
323	}
324	err = 0;
325	out:
326	cow_free(header);
327	return(err);
328	}
329
330	int init_cow_file(int fd, char cow_file, char backing_file, int sectorsize,
331	int alignment, int *bitmap_offset_out,
332	unsigned long bitmap_len_out, int data_offset_out)
333	{
334	unsigned long long size, offset;
335	char zero = 0;
336	int err;
337
338	err = write_cow_header(cow_file, fd, backing_file, sectorsize,
339	alignment, &size);
340	if(err)
341	goto out;
342
343	*bitmap_offset_out = ROUND_UP(sizeof(struct cow_header_v3), alignment);
344	cow_sizes(COW_VERSION, size, sectorsize, alignment, *bitmap_offset_out,
345	bitmap_len_out, data_offset_out);
346
347	offset = *data_offset_out + size - sizeof(zero);
348	err = cow_seek_file(fd, offset);
349	if(err < 0){
350	cow_printf("cow bitmap lseek failed : err = %d\n", -err);
351	goto out;
352	}
353
354	/* does not really matter how much we write it is just to set EOF
355	* this also sets the entire COW bitmap
356	* to zero without having to allocate it
357	*/
358	err = cow_write_file(fd, &zero, sizeof(zero));
359	if(err != sizeof(zero)){
360	cow_printf("Write of bitmap to new COW file '%s' failed, "
361	"err = %d\n", cow_file, -err);
362	err = -EINVAL;
363	goto out;
364	}
365
366	return(0);
367
368	out:
369	return(err);
370	}
371
372	/*
373	* ---------------------------------------------------------------------------
374	* Local variables:
375	* c-file-style: "linux"
376	* End:
377	*/