xref: /linux/drivers/nvdimm/pmem.c (revision be58f7103700a68d5c7ca60a2bc0b309907599ab)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Persistent Memory Driver
4  *
5  * Copyright (c) 2014-2015, Intel Corporation.
6  * Copyright (c) 2015, Christoph Hellwig <hch@lst.de>.
7  * Copyright (c) 2015, Boaz Harrosh <boaz@plexistor.com>.
8  */
9 
10 #include <linux/blkdev.h>
11 #include <linux/pagemap.h>
12 #include <linux/hdreg.h>
13 #include <linux/init.h>
14 #include <linux/platform_device.h>
15 #include <linux/set_memory.h>
16 #include <linux/module.h>
17 #include <linux/moduleparam.h>
18 #include <linux/badblocks.h>
19 #include <linux/memremap.h>
20 #include <linux/vmalloc.h>
21 #include <linux/blk-mq.h>
22 #include <linux/pfn_t.h>
23 #include <linux/slab.h>
24 #include <linux/uio.h>
25 #include <linux/dax.h>
26 #include <linux/nd.h>
27 #include <linux/mm.h>
28 #include <asm/cacheflush.h>
29 #include "pmem.h"
30 #include "btt.h"
31 #include "pfn.h"
32 #include "nd.h"
33 
34 static struct device *to_dev(struct pmem_device *pmem)
35 {
36 	/*
37 	 * nvdimm bus services need a 'dev' parameter, and we record the device
38 	 * at init in bb.dev.
39 	 */
40 	return pmem->bb.dev;
41 }
42 
43 static struct nd_region *to_region(struct pmem_device *pmem)
44 {
45 	return to_nd_region(to_dev(pmem)->parent);
46 }
47 
48 static void hwpoison_clear(struct pmem_device *pmem,
49 		phys_addr_t phys, unsigned int len)
50 {
51 	unsigned long pfn_start, pfn_end, pfn;
52 
53 	/* only pmem in the linear map supports HWPoison */
54 	if (is_vmalloc_addr(pmem->virt_addr))
55 		return;
56 
57 	pfn_start = PHYS_PFN(phys);
58 	pfn_end = pfn_start + PHYS_PFN(len);
59 	for (pfn = pfn_start; pfn < pfn_end; pfn++) {
60 		struct page *page = pfn_to_page(pfn);
61 
62 		/*
63 		 * Note, no need to hold a get_dev_pagemap() reference
64 		 * here since we're in the driver I/O path and
65 		 * outstanding I/O requests pin the dev_pagemap.
66 		 */
67 		if (test_and_clear_pmem_poison(page))
68 			clear_mce_nospec(pfn);
69 	}
70 }
71 
72 static blk_status_t pmem_clear_poison(struct pmem_device *pmem,
73 		phys_addr_t offset, unsigned int len)
74 {
75 	struct device *dev = to_dev(pmem);
76 	sector_t sector;
77 	long cleared;
78 	blk_status_t rc = BLK_STS_OK;
79 
80 	sector = (offset - pmem->data_offset) / 512;
81 
82 	cleared = nvdimm_clear_poison(dev, pmem->phys_addr + offset, len);
83 	if (cleared < len)
84 		rc = BLK_STS_IOERR;
85 	if (cleared > 0 && cleared / 512) {
86 		hwpoison_clear(pmem, pmem->phys_addr + offset, cleared);
87 		cleared /= 512;
88 		dev_dbg(dev, "%#llx clear %ld sector%s\n",
89 				(unsigned long long) sector, cleared,
90 				cleared > 1 ? "s" : "");
91 		badblocks_clear(&pmem->bb, sector, cleared);
92 		if (pmem->bb_state)
93 			sysfs_notify_dirent(pmem->bb_state);
94 	}
95 
96 	arch_invalidate_pmem(pmem->virt_addr + offset, len);
97 
98 	return rc;
99 }
100 
101 static void write_pmem(void *pmem_addr, struct page *page,
102 		unsigned int off, unsigned int len)
103 {
104 	unsigned int chunk;
105 	void *mem;
106 
107 	while (len) {
108 		mem = kmap_atomic(page);
109 		chunk = min_t(unsigned int, len, PAGE_SIZE - off);
110 		memcpy_flushcache(pmem_addr, mem + off, chunk);
111 		kunmap_atomic(mem);
112 		len -= chunk;
113 		off = 0;
114 		page++;
115 		pmem_addr += chunk;
116 	}
117 }
118 
119 static blk_status_t read_pmem(struct page *page, unsigned int off,
120 		void *pmem_addr, unsigned int len)
121 {
122 	unsigned int chunk;
123 	unsigned long rem;
124 	void *mem;
125 
126 	while (len) {
127 		mem = kmap_atomic(page);
128 		chunk = min_t(unsigned int, len, PAGE_SIZE - off);
129 		rem = copy_mc_to_kernel(mem + off, pmem_addr, chunk);
130 		kunmap_atomic(mem);
131 		if (rem)
132 			return BLK_STS_IOERR;
133 		len -= chunk;
134 		off = 0;
135 		page++;
136 		pmem_addr += chunk;
137 	}
138 	return BLK_STS_OK;
139 }
140 
141 static blk_status_t pmem_do_read(struct pmem_device *pmem,
142 			struct page *page, unsigned int page_off,
143 			sector_t sector, unsigned int len)
144 {
145 	blk_status_t rc;
146 	phys_addr_t pmem_off = sector * 512 + pmem->data_offset;
147 	void *pmem_addr = pmem->virt_addr + pmem_off;
148 
149 	if (unlikely(is_bad_pmem(&pmem->bb, sector, len)))
150 		return BLK_STS_IOERR;
151 
152 	rc = read_pmem(page, page_off, pmem_addr, len);
153 	flush_dcache_page(page);
154 	return rc;
155 }
156 
157 static blk_status_t pmem_do_write(struct pmem_device *pmem,
158 			struct page *page, unsigned int page_off,
159 			sector_t sector, unsigned int len)
160 {
161 	blk_status_t rc = BLK_STS_OK;
162 	bool bad_pmem = false;
163 	phys_addr_t pmem_off = sector * 512 + pmem->data_offset;
164 	void *pmem_addr = pmem->virt_addr + pmem_off;
165 
166 	if (unlikely(is_bad_pmem(&pmem->bb, sector, len)))
167 		bad_pmem = true;
168 
169 	/*
170 	 * Note that we write the data both before and after
171 	 * clearing poison.  The write before clear poison
172 	 * handles situations where the latest written data is
173 	 * preserved and the clear poison operation simply marks
174 	 * the address range as valid without changing the data.
175 	 * In this case application software can assume that an
176 	 * interrupted write will either return the new good
177 	 * data or an error.
178 	 *
179 	 * However, if pmem_clear_poison() leaves the data in an
180 	 * indeterminate state we need to perform the write
181 	 * after clear poison.
182 	 */
183 	flush_dcache_page(page);
184 	write_pmem(pmem_addr, page, page_off, len);
185 	if (unlikely(bad_pmem)) {
186 		rc = pmem_clear_poison(pmem, pmem_off, len);
187 		write_pmem(pmem_addr, page, page_off, len);
188 	}
189 
190 	return rc;
191 }
192 
193 static blk_qc_t pmem_submit_bio(struct bio *bio)
194 {
195 	int ret = 0;
196 	blk_status_t rc = 0;
197 	bool do_acct;
198 	unsigned long start;
199 	struct bio_vec bvec;
200 	struct bvec_iter iter;
201 	struct pmem_device *pmem = bio->bi_bdev->bd_disk->private_data;
202 	struct nd_region *nd_region = to_region(pmem);
203 
204 	if (bio->bi_opf & REQ_PREFLUSH)
205 		ret = nvdimm_flush(nd_region, bio);
206 
207 	do_acct = blk_queue_io_stat(bio->bi_bdev->bd_disk->queue);
208 	if (do_acct)
209 		start = bio_start_io_acct(bio);
210 	bio_for_each_segment(bvec, bio, iter) {
211 		if (op_is_write(bio_op(bio)))
212 			rc = pmem_do_write(pmem, bvec.bv_page, bvec.bv_offset,
213 				iter.bi_sector, bvec.bv_len);
214 		else
215 			rc = pmem_do_read(pmem, bvec.bv_page, bvec.bv_offset,
216 				iter.bi_sector, bvec.bv_len);
217 		if (rc) {
218 			bio->bi_status = rc;
219 			break;
220 		}
221 	}
222 	if (do_acct)
223 		bio_end_io_acct(bio, start);
224 
225 	if (bio->bi_opf & REQ_FUA)
226 		ret = nvdimm_flush(nd_region, bio);
227 
228 	if (ret)
229 		bio->bi_status = errno_to_blk_status(ret);
230 
231 	bio_endio(bio);
232 	return BLK_QC_T_NONE;
233 }
234 
235 static int pmem_rw_page(struct block_device *bdev, sector_t sector,
236 		       struct page *page, unsigned int op)
237 {
238 	struct pmem_device *pmem = bdev->bd_disk->private_data;
239 	blk_status_t rc;
240 
241 	if (op_is_write(op))
242 		rc = pmem_do_write(pmem, page, 0, sector, thp_size(page));
243 	else
244 		rc = pmem_do_read(pmem, page, 0, sector, thp_size(page));
245 	/*
246 	 * The ->rw_page interface is subtle and tricky.  The core
247 	 * retries on any error, so we can only invoke page_endio() in
248 	 * the successful completion case.  Otherwise, we'll see crashes
249 	 * caused by double completion.
250 	 */
251 	if (rc == 0)
252 		page_endio(page, op_is_write(op), 0);
253 
254 	return blk_status_to_errno(rc);
255 }
256 
257 /* see "strong" declaration in tools/testing/nvdimm/pmem-dax.c */
258 __weak long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
259 		long nr_pages, void **kaddr, pfn_t *pfn)
260 {
261 	resource_size_t offset = PFN_PHYS(pgoff) + pmem->data_offset;
262 
263 	if (unlikely(is_bad_pmem(&pmem->bb, PFN_PHYS(pgoff) / 512,
264 					PFN_PHYS(nr_pages))))
265 		return -EIO;
266 
267 	if (kaddr)
268 		*kaddr = pmem->virt_addr + offset;
269 	if (pfn)
270 		*pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
271 
272 	/*
273 	 * If badblocks are present, limit known good range to the
274 	 * requested range.
275 	 */
276 	if (unlikely(pmem->bb.count))
277 		return nr_pages;
278 	return PHYS_PFN(pmem->size - pmem->pfn_pad - offset);
279 }
280 
281 static const struct block_device_operations pmem_fops = {
282 	.owner =		THIS_MODULE,
283 	.submit_bio =		pmem_submit_bio,
284 	.rw_page =		pmem_rw_page,
285 };
286 
287 static int pmem_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
288 				    size_t nr_pages)
289 {
290 	struct pmem_device *pmem = dax_get_private(dax_dev);
291 
292 	return blk_status_to_errno(pmem_do_write(pmem, ZERO_PAGE(0), 0,
293 				   PFN_PHYS(pgoff) >> SECTOR_SHIFT,
294 				   PAGE_SIZE));
295 }
296 
297 static long pmem_dax_direct_access(struct dax_device *dax_dev,
298 		pgoff_t pgoff, long nr_pages, void **kaddr, pfn_t *pfn)
299 {
300 	struct pmem_device *pmem = dax_get_private(dax_dev);
301 
302 	return __pmem_direct_access(pmem, pgoff, nr_pages, kaddr, pfn);
303 }
304 
305 /*
306  * Use the 'no check' versions of copy_from_iter_flushcache() and
307  * copy_mc_to_iter() to bypass HARDENED_USERCOPY overhead. Bounds
308  * checking, both file offset and device offset, is handled by
309  * dax_iomap_actor()
310  */
311 static size_t pmem_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
312 		void *addr, size_t bytes, struct iov_iter *i)
313 {
314 	return _copy_from_iter_flushcache(addr, bytes, i);
315 }
316 
317 static size_t pmem_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff,
318 		void *addr, size_t bytes, struct iov_iter *i)
319 {
320 	return _copy_mc_to_iter(addr, bytes, i);
321 }
322 
323 static const struct dax_operations pmem_dax_ops = {
324 	.direct_access = pmem_dax_direct_access,
325 	.dax_supported = generic_fsdax_supported,
326 	.copy_from_iter = pmem_copy_from_iter,
327 	.copy_to_iter = pmem_copy_to_iter,
328 	.zero_page_range = pmem_dax_zero_page_range,
329 };
330 
331 static const struct attribute_group *pmem_attribute_groups[] = {
332 	&dax_attribute_group,
333 	NULL,
334 };
335 
336 static void pmem_pagemap_cleanup(struct dev_pagemap *pgmap)
337 {
338 	struct pmem_device *pmem = pgmap->owner;
339 
340 	blk_cleanup_disk(pmem->disk);
341 }
342 
343 static void pmem_release_queue(void *pgmap)
344 {
345 	pmem_pagemap_cleanup(pgmap);
346 }
347 
348 static void pmem_pagemap_kill(struct dev_pagemap *pgmap)
349 {
350 	struct request_queue *q =
351 		container_of(pgmap->ref, struct request_queue, q_usage_counter);
352 
353 	blk_freeze_queue_start(q);
354 }
355 
356 static void pmem_release_disk(void *__pmem)
357 {
358 	struct pmem_device *pmem = __pmem;
359 
360 	kill_dax(pmem->dax_dev);
361 	put_dax(pmem->dax_dev);
362 	del_gendisk(pmem->disk);
363 }
364 
365 static const struct dev_pagemap_ops fsdax_pagemap_ops = {
366 	.kill			= pmem_pagemap_kill,
367 	.cleanup		= pmem_pagemap_cleanup,
368 };
369 
370 static int pmem_attach_disk(struct device *dev,
371 		struct nd_namespace_common *ndns)
372 {
373 	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
374 	struct nd_region *nd_region = to_nd_region(dev->parent);
375 	int nid = dev_to_node(dev), fua;
376 	struct resource *res = &nsio->res;
377 	struct range bb_range;
378 	struct nd_pfn *nd_pfn = NULL;
379 	struct dax_device *dax_dev;
380 	struct nd_pfn_sb *pfn_sb;
381 	struct pmem_device *pmem;
382 	struct request_queue *q;
383 	struct device *gendev;
384 	struct gendisk *disk;
385 	void *addr;
386 	int rc;
387 	unsigned long flags = 0UL;
388 
389 	pmem = devm_kzalloc(dev, sizeof(*pmem), GFP_KERNEL);
390 	if (!pmem)
391 		return -ENOMEM;
392 
393 	rc = devm_namespace_enable(dev, ndns, nd_info_block_reserve());
394 	if (rc)
395 		return rc;
396 
397 	/* while nsio_rw_bytes is active, parse a pfn info block if present */
398 	if (is_nd_pfn(dev)) {
399 		nd_pfn = to_nd_pfn(dev);
400 		rc = nvdimm_setup_pfn(nd_pfn, &pmem->pgmap);
401 		if (rc)
402 			return rc;
403 	}
404 
405 	/* we're attaching a block device, disable raw namespace access */
406 	devm_namespace_disable(dev, ndns);
407 
408 	dev_set_drvdata(dev, pmem);
409 	pmem->phys_addr = res->start;
410 	pmem->size = resource_size(res);
411 	fua = nvdimm_has_flush(nd_region);
412 	if (!IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) || fua < 0) {
413 		dev_warn(dev, "unable to guarantee persistence of writes\n");
414 		fua = 0;
415 	}
416 
417 	if (!devm_request_mem_region(dev, res->start, resource_size(res),
418 				dev_name(&ndns->dev))) {
419 		dev_warn(dev, "could not reserve region %pR\n", res);
420 		return -EBUSY;
421 	}
422 
423 	disk = blk_alloc_disk(nid);
424 	if (!disk)
425 		return -ENOMEM;
426 	q = disk->queue;
427 
428 	pmem->disk = disk;
429 	pmem->pgmap.owner = pmem;
430 	pmem->pfn_flags = PFN_DEV;
431 	pmem->pgmap.ref = &q->q_usage_counter;
432 	if (is_nd_pfn(dev)) {
433 		pmem->pgmap.type = MEMORY_DEVICE_FS_DAX;
434 		pmem->pgmap.ops = &fsdax_pagemap_ops;
435 		addr = devm_memremap_pages(dev, &pmem->pgmap);
436 		pfn_sb = nd_pfn->pfn_sb;
437 		pmem->data_offset = le64_to_cpu(pfn_sb->dataoff);
438 		pmem->pfn_pad = resource_size(res) -
439 			range_len(&pmem->pgmap.range);
440 		pmem->pfn_flags |= PFN_MAP;
441 		bb_range = pmem->pgmap.range;
442 		bb_range.start += pmem->data_offset;
443 	} else if (pmem_should_map_pages(dev)) {
444 		pmem->pgmap.range.start = res->start;
445 		pmem->pgmap.range.end = res->end;
446 		pmem->pgmap.nr_range = 1;
447 		pmem->pgmap.type = MEMORY_DEVICE_FS_DAX;
448 		pmem->pgmap.ops = &fsdax_pagemap_ops;
449 		addr = devm_memremap_pages(dev, &pmem->pgmap);
450 		pmem->pfn_flags |= PFN_MAP;
451 		bb_range = pmem->pgmap.range;
452 	} else {
453 		addr = devm_memremap(dev, pmem->phys_addr,
454 				pmem->size, ARCH_MEMREMAP_PMEM);
455 		if (devm_add_action_or_reset(dev, pmem_release_queue,
456 					&pmem->pgmap))
457 			return -ENOMEM;
458 		bb_range.start =  res->start;
459 		bb_range.end = res->end;
460 	}
461 
462 	if (IS_ERR(addr))
463 		return PTR_ERR(addr);
464 	pmem->virt_addr = addr;
465 
466 	blk_queue_write_cache(q, true, fua);
467 	blk_queue_physical_block_size(q, PAGE_SIZE);
468 	blk_queue_logical_block_size(q, pmem_sector_size(ndns));
469 	blk_queue_max_hw_sectors(q, UINT_MAX);
470 	blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
471 	if (pmem->pfn_flags & PFN_MAP)
472 		blk_queue_flag_set(QUEUE_FLAG_DAX, q);
473 
474 	disk->fops		= &pmem_fops;
475 	disk->private_data	= pmem;
476 	nvdimm_namespace_disk_name(ndns, disk->disk_name);
477 	set_capacity(disk, (pmem->size - pmem->pfn_pad - pmem->data_offset)
478 			/ 512);
479 	if (devm_init_badblocks(dev, &pmem->bb))
480 		return -ENOMEM;
481 	nvdimm_badblocks_populate(nd_region, &pmem->bb, &bb_range);
482 	disk->bb = &pmem->bb;
483 
484 	if (is_nvdimm_sync(nd_region))
485 		flags = DAXDEV_F_SYNC;
486 	dax_dev = alloc_dax(pmem, disk->disk_name, &pmem_dax_ops, flags);
487 	if (IS_ERR(dax_dev)) {
488 		return PTR_ERR(dax_dev);
489 	}
490 	dax_write_cache(dax_dev, nvdimm_has_cache(nd_region));
491 	pmem->dax_dev = dax_dev;
492 	gendev = disk_to_dev(disk);
493 	gendev->groups = pmem_attribute_groups;
494 
495 	device_add_disk(dev, disk, NULL);
496 	if (devm_add_action_or_reset(dev, pmem_release_disk, pmem))
497 		return -ENOMEM;
498 
499 	nvdimm_check_and_set_ro(disk);
500 
501 	pmem->bb_state = sysfs_get_dirent(disk_to_dev(disk)->kobj.sd,
502 					  "badblocks");
503 	if (!pmem->bb_state)
504 		dev_warn(dev, "'badblocks' notification disabled\n");
505 
506 	return 0;
507 }
508 
509 static int nd_pmem_probe(struct device *dev)
510 {
511 	int ret;
512 	struct nd_namespace_common *ndns;
513 
514 	ndns = nvdimm_namespace_common_probe(dev);
515 	if (IS_ERR(ndns))
516 		return PTR_ERR(ndns);
517 
518 	if (is_nd_btt(dev))
519 		return nvdimm_namespace_attach_btt(ndns);
520 
521 	if (is_nd_pfn(dev))
522 		return pmem_attach_disk(dev, ndns);
523 
524 	ret = devm_namespace_enable(dev, ndns, nd_info_block_reserve());
525 	if (ret)
526 		return ret;
527 
528 	ret = nd_btt_probe(dev, ndns);
529 	if (ret == 0)
530 		return -ENXIO;
531 
532 	/*
533 	 * We have two failure conditions here, there is no
534 	 * info reserver block or we found a valid info reserve block
535 	 * but failed to initialize the pfn superblock.
536 	 *
537 	 * For the first case consider namespace as a raw pmem namespace
538 	 * and attach a disk.
539 	 *
540 	 * For the latter, consider this a success and advance the namespace
541 	 * seed.
542 	 */
543 	ret = nd_pfn_probe(dev, ndns);
544 	if (ret == 0)
545 		return -ENXIO;
546 	else if (ret == -EOPNOTSUPP)
547 		return ret;
548 
549 	ret = nd_dax_probe(dev, ndns);
550 	if (ret == 0)
551 		return -ENXIO;
552 	else if (ret == -EOPNOTSUPP)
553 		return ret;
554 
555 	/* probe complete, attach handles namespace enabling */
556 	devm_namespace_disable(dev, ndns);
557 
558 	return pmem_attach_disk(dev, ndns);
559 }
560 
561 static void nd_pmem_remove(struct device *dev)
562 {
563 	struct pmem_device *pmem = dev_get_drvdata(dev);
564 
565 	if (is_nd_btt(dev))
566 		nvdimm_namespace_detach_btt(to_nd_btt(dev));
567 	else {
568 		/*
569 		 * Note, this assumes nd_device_lock() context to not
570 		 * race nd_pmem_notify()
571 		 */
572 		sysfs_put(pmem->bb_state);
573 		pmem->bb_state = NULL;
574 	}
575 	nvdimm_flush(to_nd_region(dev->parent), NULL);
576 }
577 
578 static void nd_pmem_shutdown(struct device *dev)
579 {
580 	nvdimm_flush(to_nd_region(dev->parent), NULL);
581 }
582 
583 static void pmem_revalidate_poison(struct device *dev)
584 {
585 	struct nd_region *nd_region;
586 	resource_size_t offset = 0, end_trunc = 0;
587 	struct nd_namespace_common *ndns;
588 	struct nd_namespace_io *nsio;
589 	struct badblocks *bb;
590 	struct range range;
591 	struct kernfs_node *bb_state;
592 
593 	if (is_nd_btt(dev)) {
594 		struct nd_btt *nd_btt = to_nd_btt(dev);
595 
596 		ndns = nd_btt->ndns;
597 		nd_region = to_nd_region(ndns->dev.parent);
598 		nsio = to_nd_namespace_io(&ndns->dev);
599 		bb = &nsio->bb;
600 		bb_state = NULL;
601 	} else {
602 		struct pmem_device *pmem = dev_get_drvdata(dev);
603 
604 		nd_region = to_region(pmem);
605 		bb = &pmem->bb;
606 		bb_state = pmem->bb_state;
607 
608 		if (is_nd_pfn(dev)) {
609 			struct nd_pfn *nd_pfn = to_nd_pfn(dev);
610 			struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
611 
612 			ndns = nd_pfn->ndns;
613 			offset = pmem->data_offset +
614 					__le32_to_cpu(pfn_sb->start_pad);
615 			end_trunc = __le32_to_cpu(pfn_sb->end_trunc);
616 		} else {
617 			ndns = to_ndns(dev);
618 		}
619 
620 		nsio = to_nd_namespace_io(&ndns->dev);
621 	}
622 
623 	range.start = nsio->res.start + offset;
624 	range.end = nsio->res.end - end_trunc;
625 	nvdimm_badblocks_populate(nd_region, bb, &range);
626 	if (bb_state)
627 		sysfs_notify_dirent(bb_state);
628 }
629 
630 static void pmem_revalidate_region(struct device *dev)
631 {
632 	struct pmem_device *pmem;
633 
634 	if (is_nd_btt(dev)) {
635 		struct nd_btt *nd_btt = to_nd_btt(dev);
636 		struct btt *btt = nd_btt->btt;
637 
638 		nvdimm_check_and_set_ro(btt->btt_disk);
639 		return;
640 	}
641 
642 	pmem = dev_get_drvdata(dev);
643 	nvdimm_check_and_set_ro(pmem->disk);
644 }
645 
646 static void nd_pmem_notify(struct device *dev, enum nvdimm_event event)
647 {
648 	switch (event) {
649 	case NVDIMM_REVALIDATE_POISON:
650 		pmem_revalidate_poison(dev);
651 		break;
652 	case NVDIMM_REVALIDATE_REGION:
653 		pmem_revalidate_region(dev);
654 		break;
655 	default:
656 		dev_WARN_ONCE(dev, 1, "notify: unknown event: %d\n", event);
657 		break;
658 	}
659 }
660 
661 MODULE_ALIAS("pmem");
662 MODULE_ALIAS_ND_DEVICE(ND_DEVICE_NAMESPACE_IO);
663 MODULE_ALIAS_ND_DEVICE(ND_DEVICE_NAMESPACE_PMEM);
664 static struct nd_device_driver nd_pmem_driver = {
665 	.probe = nd_pmem_probe,
666 	.remove = nd_pmem_remove,
667 	.notify = nd_pmem_notify,
668 	.shutdown = nd_pmem_shutdown,
669 	.drv = {
670 		.name = "nd_pmem",
671 	},
672 	.type = ND_DRIVER_NAMESPACE_IO | ND_DRIVER_NAMESPACE_PMEM,
673 };
674 
675 module_nd_driver(nd_pmem_driver);
676 
677 MODULE_AUTHOR("Ross Zwisler <ross.zwisler@linux.intel.com>");
678 MODULE_LICENSE("GPL v2");
679