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/drivers/mtd/ubi/gluebi.c

https://bitbucket.org/slukk/jb-tsm-kernel-4.2
C | 542 lines | 316 code | 66 blank | 160 comment | 53 complexity | 55db3183affd16e3a61af286b5e54188 MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
  1/*
  2 * Copyright (c) International Business Machines Corp., 2006
  3 *
  4 * This program is free software; you can redistribute it and/or modify
  5 * it under the terms of the GNU General Public License as published by
  6 * the Free Software Foundation; either version 2 of the License, or
  7 * (at your option) any later version.
  8 *
  9 * This program is distributed in the hope that it will be useful,
 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
 12 * the GNU General Public License for more details.
 13 *
 14 * You should have received a copy of the GNU General Public License
 15 * along with this program; if not, write to the Free Software
 16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 17 *
 18 * Author: Artem Bityutskiy (Битюцкий Артём), Joern Engel
 19 */
 20
 21/*
 22 * This is a small driver which implements fake MTD devices on top of UBI
 23 * volumes. This sounds strange, but it is in fact quite useful to make
 24 * MTD-oriented software (including all the legacy software) work on top of
 25 * UBI.
 26 *
 27 * Gluebi emulates MTD devices of "MTD_UBIVOLUME" type. Their minimal I/O unit
 28 * size (@mtd->writesize) is equivalent to the UBI minimal I/O unit. The
 29 * eraseblock size is equivalent to the logical eraseblock size of the volume.
 30 */
 31
 32#include <linux/err.h>
 33#include <linux/list.h>
 34#include <linux/slab.h>
 35#include <linux/sched.h>
 36#include <linux/math64.h>
 37#include <linux/module.h>
 38#include <linux/mutex.h>
 39#include <linux/mtd/ubi.h>
 40#include <linux/mtd/mtd.h>
 41#include "ubi-media.h"
 42
 43#define err_msg(fmt, ...)                                   \
 44	printk(KERN_DEBUG "gluebi (pid %d): %s: " fmt "\n", \
 45	       current->pid, __func__, ##__VA_ARGS__)
 46
 47/**
 48 * struct gluebi_device - a gluebi device description data structure.
 49 * @mtd: emulated MTD device description object
 50 * @refcnt: gluebi device reference count
 51 * @desc: UBI volume descriptor
 52 * @ubi_num: UBI device number this gluebi device works on
 53 * @vol_id: ID of UBI volume this gluebi device works on
 54 * @list: link in a list of gluebi devices
 55 */
 56struct gluebi_device {
 57	struct mtd_info mtd;
 58	int refcnt;
 59	struct ubi_volume_desc *desc;
 60	int ubi_num;
 61	int vol_id;
 62	struct list_head list;
 63};
 64
 65/* List of all gluebi devices */
 66static LIST_HEAD(gluebi_devices);
 67static DEFINE_MUTEX(devices_mutex);
 68
 69/**
 70 * find_gluebi_nolock - find a gluebi device.
 71 * @ubi_num: UBI device number
 72 * @vol_id: volume ID
 73 *
 74 * This function seraches for gluebi device corresponding to UBI device
 75 * @ubi_num and UBI volume @vol_id. Returns the gluebi device description
 76 * object in case of success and %NULL in case of failure. The caller has to
 77 * have the &devices_mutex locked.
 78 */
 79static struct gluebi_device *find_gluebi_nolock(int ubi_num, int vol_id)
 80{
 81	struct gluebi_device *gluebi;
 82
 83	list_for_each_entry(gluebi, &gluebi_devices, list)
 84		if (gluebi->ubi_num == ubi_num && gluebi->vol_id == vol_id)
 85			return gluebi;
 86	return NULL;
 87}
 88
 89/**
 90 * gluebi_get_device - get MTD device reference.
 91 * @mtd: the MTD device description object
 92 *
 93 * This function is called every time the MTD device is being opened and
 94 * implements the MTD get_device() operation. Returns zero in case of success
 95 * and a negative error code in case of failure.
 96 */
 97static int gluebi_get_device(struct mtd_info *mtd)
 98{
 99	struct gluebi_device *gluebi;
100	int ubi_mode = UBI_READONLY;
101
102	if (!try_module_get(THIS_MODULE))
103		return -ENODEV;
104
105	if (mtd->flags & MTD_WRITEABLE)
106		ubi_mode = UBI_READWRITE;
107
108	gluebi = container_of(mtd, struct gluebi_device, mtd);
109	mutex_lock(&devices_mutex);
110	if (gluebi->refcnt > 0) {
111		/*
112		 * The MTD device is already referenced and this is just one
113		 * more reference. MTD allows many users to open the same
114		 * volume simultaneously and do not distinguish between
115		 * readers/writers/exclusive openers as UBI does. So we do not
116		 * open the UBI volume again - just increase the reference
117		 * counter and return.
118		 */
119		gluebi->refcnt += 1;
120		mutex_unlock(&devices_mutex);
121		return 0;
122	}
123
124	/*
125	 * This is the first reference to this UBI volume via the MTD device
126	 * interface. Open the corresponding volume in read-write mode.
127	 */
128	gluebi->desc = ubi_open_volume(gluebi->ubi_num, gluebi->vol_id,
129				       ubi_mode);
130	if (IS_ERR(gluebi->desc)) {
131		mutex_unlock(&devices_mutex);
132		module_put(THIS_MODULE);
133		return PTR_ERR(gluebi->desc);
134	}
135	gluebi->refcnt += 1;
136	mutex_unlock(&devices_mutex);
137	return 0;
138}
139
140/**
141 * gluebi_put_device - put MTD device reference.
142 * @mtd: the MTD device description object
143 *
144 * This function is called every time the MTD device is being put. Returns
145 * zero in case of success and a negative error code in case of failure.
146 */
147static void gluebi_put_device(struct mtd_info *mtd)
148{
149	struct gluebi_device *gluebi;
150
151	gluebi = container_of(mtd, struct gluebi_device, mtd);
152	mutex_lock(&devices_mutex);
153	gluebi->refcnt -= 1;
154	if (gluebi->refcnt == 0)
155		ubi_close_volume(gluebi->desc);
156	module_put(THIS_MODULE);
157	mutex_unlock(&devices_mutex);
158}
159
160/**
161 * gluebi_read - read operation of emulated MTD devices.
162 * @mtd: MTD device description object
163 * @from: absolute offset from where to read
164 * @len: how many bytes to read
165 * @retlen: count of read bytes is returned here
166 * @buf: buffer to store the read data
167 *
168 * This function returns zero in case of success and a negative error code in
169 * case of failure.
170 */
171static int gluebi_read(struct mtd_info *mtd, loff_t from, size_t len,
172		       size_t *retlen, unsigned char *buf)
173{
174	int err = 0, lnum, offs, total_read;
175	struct gluebi_device *gluebi;
176
177	if (len < 0 || from < 0 || from + len > mtd->size)
178		return -EINVAL;
179
180	gluebi = container_of(mtd, struct gluebi_device, mtd);
181
182	lnum = div_u64_rem(from, mtd->erasesize, &offs);
183	total_read = len;
184	while (total_read) {
185		size_t to_read = mtd->erasesize - offs;
186
187		if (to_read > total_read)
188			to_read = total_read;
189
190		err = ubi_read(gluebi->desc, lnum, buf, offs, to_read);
191		if (err)
192			break;
193
194		lnum += 1;
195		offs = 0;
196		total_read -= to_read;
197		buf += to_read;
198	}
199
200	*retlen = len - total_read;
201	return err;
202}
203
204/**
205 * gluebi_write - write operation of emulated MTD devices.
206 * @mtd: MTD device description object
207 * @to: absolute offset where to write
208 * @len: how many bytes to write
209 * @retlen: count of written bytes is returned here
210 * @buf: buffer with data to write
211 *
212 * This function returns zero in case of success and a negative error code in
213 * case of failure.
214 */
215static int gluebi_write(struct mtd_info *mtd, loff_t to, size_t len,
216			size_t *retlen, const u_char *buf)
217{
218	int err = 0, lnum, offs, total_written;
219	struct gluebi_device *gluebi;
220
221	if (len < 0 || to < 0 || len + to > mtd->size)
222		return -EINVAL;
223
224	gluebi = container_of(mtd, struct gluebi_device, mtd);
225
226	if (!(mtd->flags & MTD_WRITEABLE))
227		return -EROFS;
228
229	lnum = div_u64_rem(to, mtd->erasesize, &offs);
230
231	if (len % mtd->writesize || offs % mtd->writesize)
232		return -EINVAL;
233
234	total_written = len;
235	while (total_written) {
236		size_t to_write = mtd->erasesize - offs;
237
238		if (to_write > total_written)
239			to_write = total_written;
240
241		err = ubi_write(gluebi->desc, lnum, buf, offs, to_write);
242		if (err)
243			break;
244
245		lnum += 1;
246		offs = 0;
247		total_written -= to_write;
248		buf += to_write;
249	}
250
251	*retlen = len - total_written;
252	return err;
253}
254
255/**
256 * gluebi_erase - erase operation of emulated MTD devices.
257 * @mtd: the MTD device description object
258 * @instr: the erase operation description
259 *
260 * This function calls the erase callback when finishes. Returns zero in case
261 * of success and a negative error code in case of failure.
262 */
263static int gluebi_erase(struct mtd_info *mtd, struct erase_info *instr)
264{
265	int err, i, lnum, count;
266	struct gluebi_device *gluebi;
267
268	if (instr->addr < 0 || instr->addr > mtd->size - mtd->erasesize)
269		return -EINVAL;
270	if (instr->len < 0 || instr->addr + instr->len > mtd->size)
271		return -EINVAL;
272	if (mtd_mod_by_ws(instr->addr, mtd) || mtd_mod_by_ws(instr->len, mtd))
273		return -EINVAL;
274
275	lnum = mtd_div_by_eb(instr->addr, mtd);
276	count = mtd_div_by_eb(instr->len, mtd);
277
278	gluebi = container_of(mtd, struct gluebi_device, mtd);
279
280	if (!(mtd->flags & MTD_WRITEABLE))
281		return -EROFS;
282
283	for (i = 0; i < count - 1; i++) {
284		err = ubi_leb_unmap(gluebi->desc, lnum + i);
285		if (err)
286			goto out_err;
287	}
288	/*
289	 * MTD erase operations are synchronous, so we have to make sure the
290	 * physical eraseblock is wiped out.
291	 *
292	 * Thus, perform leb_erase instead of leb_unmap operation - leb_erase
293	 * will wait for the end of operations
294	 */
295	err = ubi_leb_erase(gluebi->desc, lnum + i);
296	if (err)
297		goto out_err;
298
299	instr->state = MTD_ERASE_DONE;
300	mtd_erase_callback(instr);
301	return 0;
302
303out_err:
304	instr->state = MTD_ERASE_FAILED;
305	instr->fail_addr = (long long)lnum * mtd->erasesize;
306	return err;
307}
308
309/**
310 * gluebi_create - create a gluebi device for an UBI volume.
311 * @di: UBI device description object
312 * @vi: UBI volume description object
313 *
314 * This function is called when a new UBI volume is created in order to create
315 * corresponding fake MTD device. Returns zero in case of success and a
316 * negative error code in case of failure.
317 */
318static int gluebi_create(struct ubi_device_info *di,
319			 struct ubi_volume_info *vi)
320{
321	struct gluebi_device *gluebi, *g;
322	struct mtd_info *mtd;
323
324	gluebi = kzalloc(sizeof(struct gluebi_device), GFP_KERNEL);
325	if (!gluebi)
326		return -ENOMEM;
327
328	mtd = &gluebi->mtd;
329	mtd->name = kmemdup(vi->name, vi->name_len + 1, GFP_KERNEL);
330	if (!mtd->name) {
331		kfree(gluebi);
332		return -ENOMEM;
333	}
334
335	gluebi->vol_id = vi->vol_id;
336	gluebi->ubi_num = vi->ubi_num;
337	mtd->type = MTD_UBIVOLUME;
338	if (!di->ro_mode)
339		mtd->flags = MTD_WRITEABLE;
340	mtd->owner      = THIS_MODULE;
341	mtd->writesize  = di->min_io_size;
342	mtd->erasesize  = vi->usable_leb_size;
343	mtd->read       = gluebi_read;
344	mtd->write      = gluebi_write;
345	mtd->erase      = gluebi_erase;
346	mtd->get_device = gluebi_get_device;
347	mtd->put_device = gluebi_put_device;
348
349	/*
350	 * In case of dynamic a volume, MTD device size is just volume size. In
351	 * case of a static volume the size is equivalent to the amount of data
352	 * bytes.
353	 */
354	if (vi->vol_type == UBI_DYNAMIC_VOLUME)
355		mtd->size = (unsigned long long)vi->usable_leb_size * vi->size;
356	else
357		mtd->size = vi->used_bytes;
358
359	/* Just a sanity check - make sure this gluebi device does not exist */
360	mutex_lock(&devices_mutex);
361	g = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
362	if (g)
363		err_msg("gluebi MTD device %d form UBI device %d volume %d "
364			"already exists", g->mtd.index, vi->ubi_num,
365			vi->vol_id);
366	mutex_unlock(&devices_mutex);
367
368	if (mtd_device_register(mtd, NULL, 0)) {
369		err_msg("cannot add MTD device");
370		kfree(mtd->name);
371		kfree(gluebi);
372		return -ENFILE;
373	}
374
375	mutex_lock(&devices_mutex);
376	list_add_tail(&gluebi->list, &gluebi_devices);
377	mutex_unlock(&devices_mutex);
378	return 0;
379}
380
381/**
382 * gluebi_remove - remove a gluebi device.
383 * @vi: UBI volume description object
384 *
385 * This function is called when an UBI volume is removed and it removes
386 * corresponding fake MTD device. Returns zero in case of success and a
387 * negative error code in case of failure.
388 */
389static int gluebi_remove(struct ubi_volume_info *vi)
390{
391	int err = 0;
392	struct mtd_info *mtd;
393	struct gluebi_device *gluebi;
394
395	mutex_lock(&devices_mutex);
396	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
397	if (!gluebi) {
398		err_msg("got remove notification for unknown UBI device %d "
399			"volume %d", vi->ubi_num, vi->vol_id);
400		err = -ENOENT;
401	} else if (gluebi->refcnt)
402		err = -EBUSY;
403	else
404		list_del(&gluebi->list);
405	mutex_unlock(&devices_mutex);
406	if (err)
407		return err;
408
409	mtd = &gluebi->mtd;
410	err = mtd_device_unregister(mtd);
411	if (err) {
412		err_msg("cannot remove fake MTD device %d, UBI device %d, "
413			"volume %d, error %d", mtd->index, gluebi->ubi_num,
414			gluebi->vol_id, err);
415		mutex_lock(&devices_mutex);
416		list_add_tail(&gluebi->list, &gluebi_devices);
417		mutex_unlock(&devices_mutex);
418		return err;
419	}
420
421	kfree(mtd->name);
422	kfree(gluebi);
423	return 0;
424}
425
426/**
427 * gluebi_updated - UBI volume was updated notifier.
428 * @vi: volume info structure
429 *
430 * This function is called every time an UBI volume is updated. It does nothing
431 * if te volume @vol is dynamic, and changes MTD device size if the
432 * volume is static. This is needed because static volumes cannot be read past
433 * data they contain. This function returns zero in case of success and a
434 * negative error code in case of error.
435 */
436static int gluebi_updated(struct ubi_volume_info *vi)
437{
438	struct gluebi_device *gluebi;
439
440	mutex_lock(&devices_mutex);
441	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
442	if (!gluebi) {
443		mutex_unlock(&devices_mutex);
444		err_msg("got update notification for unknown UBI device %d "
445			"volume %d", vi->ubi_num, vi->vol_id);
446		return -ENOENT;
447	}
448
449	if (vi->vol_type == UBI_STATIC_VOLUME)
450		gluebi->mtd.size = vi->used_bytes;
451	mutex_unlock(&devices_mutex);
452	return 0;
453}
454
455/**
456 * gluebi_resized - UBI volume was re-sized notifier.
457 * @vi: volume info structure
458 *
459 * This function is called every time an UBI volume is re-size. It changes the
460 * corresponding fake MTD device size. This function returns zero in case of
461 * success and a negative error code in case of error.
462 */
463static int gluebi_resized(struct ubi_volume_info *vi)
464{
465	struct gluebi_device *gluebi;
466
467	mutex_lock(&devices_mutex);
468	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
469	if (!gluebi) {
470		mutex_unlock(&devices_mutex);
471		err_msg("got update notification for unknown UBI device %d "
472			"volume %d", vi->ubi_num, vi->vol_id);
473		return -ENOENT;
474	}
475	gluebi->mtd.size = vi->used_bytes;
476	mutex_unlock(&devices_mutex);
477	return 0;
478}
479
480/**
481 * gluebi_notify - UBI notification handler.
482 * @nb: registered notifier block
483 * @l: notification type
484 * @ptr: pointer to the &struct ubi_notification object
485 */
486static int gluebi_notify(struct notifier_block *nb, unsigned long l,
487			 void *ns_ptr)
488{
489	struct ubi_notification *nt = ns_ptr;
490
491	switch (l) {
492	case UBI_VOLUME_ADDED:
493		gluebi_create(&nt->di, &nt->vi);
494		break;
495	case UBI_VOLUME_REMOVED:
496		gluebi_remove(&nt->vi);
497		break;
498	case UBI_VOLUME_RESIZED:
499		gluebi_resized(&nt->vi);
500		break;
501	case UBI_VOLUME_UPDATED:
502		gluebi_updated(&nt->vi);
503		break;
504	default:
505		break;
506	}
507	return NOTIFY_OK;
508}
509
510static struct notifier_block gluebi_notifier = {
511	.notifier_call	= gluebi_notify,
512};
513
514static int __init ubi_gluebi_init(void)
515{
516	return ubi_register_volume_notifier(&gluebi_notifier, 0);
517}
518
519static void __exit ubi_gluebi_exit(void)
520{
521	struct gluebi_device *gluebi, *g;
522
523	list_for_each_entry_safe(gluebi, g, &gluebi_devices, list) {
524		int err;
525		struct mtd_info *mtd = &gluebi->mtd;
526
527		err = mtd_device_unregister(mtd);
528		if (err)
529			err_msg("error %d while removing gluebi MTD device %d, "
530				"UBI device %d, volume %d - ignoring", err,
531				mtd->index, gluebi->ubi_num, gluebi->vol_id);
532		kfree(mtd->name);
533		kfree(gluebi);
534	}
535	ubi_unregister_volume_notifier(&gluebi_notifier);
536}
537
538module_init(ubi_gluebi_init);
539module_exit(ubi_gluebi_exit);
540MODULE_DESCRIPTION("MTD emulation layer over UBI volumes");
541MODULE_AUTHOR("Artem Bityutskiy, Joern Engel");
542MODULE_LICENSE("GPL");