blob: ad1b049ae2ab80a9487eaf8269f226dbb21ea4a9 [file] [log] [blame]
Josef Bacik0e9cebe2015-03-20 10:50:37 -04001/*
2 * Copyright (C) 2014 Facebook. All rights reserved.
3 *
4 * This file is released under the GPL.
5 */
6
7#include <linux/device-mapper.h>
8
9#include <linux/module.h>
10#include <linux/init.h>
11#include <linux/blkdev.h>
12#include <linux/bio.h>
13#include <linux/slab.h>
14#include <linux/kthread.h>
15#include <linux/freezer.h>
16
17#define DM_MSG_PREFIX "log-writes"
18
19/*
20 * This target will sequentially log all writes to the target device onto the
21 * log device. This is helpful for replaying writes to check for fs consistency
22 * at all times. This target provides a mechanism to mark specific events to
23 * check data at a later time. So for example you would:
24 *
25 * write data
26 * fsync
27 * dmsetup message /dev/whatever mark mymark
28 * unmount /mnt/test
29 *
30 * Then replay the log up to mymark and check the contents of the replay to
31 * verify it matches what was written.
32 *
33 * We log writes only after they have been flushed, this makes the log describe
34 * close to the order in which the data hits the actual disk, not its cache. So
35 * for example the following sequence (W means write, C means complete)
36 *
37 * Wa,Wb,Wc,Cc,Ca,FLUSH,FUAd,Cb,CFLUSH,CFUAd
38 *
39 * Would result in the log looking like this:
40 *
41 * c,a,flush,fuad,b,<other writes>,<next flush>
42 *
43 * This is meant to help expose problems where file systems do not properly wait
44 * on data being written before invoking a FLUSH. FUA bypasses cache so once it
45 * completes it is added to the log as it should be on disk.
46 *
47 * We treat DISCARDs as if they don't bypass cache so that they are logged in
48 * order of completion along with the normal writes. If we didn't do it this
49 * way we would process all the discards first and then write all the data, when
50 * in fact we want to do the data and the discard in the order that they
51 * completed.
52 */
53#define LOG_FLUSH_FLAG (1 << 0)
54#define LOG_FUA_FLAG (1 << 1)
55#define LOG_DISCARD_FLAG (1 << 2)
56#define LOG_MARK_FLAG (1 << 3)
57
Geert Uytterhoevenf4ad3172015-04-19 00:07:30 +020058#define WRITE_LOG_VERSION 1ULL
59#define WRITE_LOG_MAGIC 0x6a736677736872ULL
Josef Bacik0e9cebe2015-03-20 10:50:37 -040060
61/*
62 * The disk format for this is braindead simple.
63 *
64 * At byte 0 we have our super, followed by the following sequence for
65 * nr_entries:
66 *
67 * [ 1 sector ][ entry->nr_sectors ]
68 * [log_write_entry][ data written ]
69 *
70 * The log_write_entry takes up a full sector so we can have arbitrary length
71 * marks and it leaves us room for extra content in the future.
72 */
73
74/*
75 * Basic info about the log for userspace.
76 */
77struct log_write_super {
78 __le64 magic;
79 __le64 version;
80 __le64 nr_entries;
81 __le32 sectorsize;
82};
83
84/*
85 * sector - the sector we wrote.
86 * nr_sectors - the number of sectors we wrote.
87 * flags - flags for this log entry.
88 * data_len - the size of the data in this log entry, this is for private log
89 * entry stuff, the MARK data provided by userspace for example.
90 */
91struct log_write_entry {
92 __le64 sector;
93 __le64 nr_sectors;
94 __le64 flags;
95 __le64 data_len;
96};
97
98struct log_writes_c {
99 struct dm_dev *dev;
100 struct dm_dev *logdev;
101 u64 logged_entries;
102 u32 sectorsize;
103 atomic_t io_blocks;
104 atomic_t pending_blocks;
105 sector_t next_sector;
106 sector_t end_sector;
107 bool logging_enabled;
108 bool device_supports_discard;
109 spinlock_t blocks_lock;
110 struct list_head unflushed_blocks;
111 struct list_head logging_blocks;
112 wait_queue_head_t wait;
113 struct task_struct *log_kthread;
114};
115
116struct pending_block {
117 int vec_cnt;
118 u64 flags;
119 sector_t sector;
120 sector_t nr_sectors;
121 char *data;
122 u32 datalen;
123 struct list_head list;
124 struct bio_vec vecs[0];
125};
126
127struct per_bio_data {
128 struct pending_block *block;
129};
130
131static void put_pending_block(struct log_writes_c *lc)
132{
133 if (atomic_dec_and_test(&lc->pending_blocks)) {
134 smp_mb__after_atomic();
135 if (waitqueue_active(&lc->wait))
136 wake_up(&lc->wait);
137 }
138}
139
140static void put_io_block(struct log_writes_c *lc)
141{
142 if (atomic_dec_and_test(&lc->io_blocks)) {
143 smp_mb__after_atomic();
144 if (waitqueue_active(&lc->wait))
145 wake_up(&lc->wait);
146 }
147}
148
149static void log_end_io(struct bio *bio, int err)
150{
151 struct log_writes_c *lc = bio->bi_private;
152 struct bio_vec *bvec;
153 int i;
154
155 if (err) {
156 unsigned long flags;
157
158 DMERR("Error writing log block, error=%d", err);
159 spin_lock_irqsave(&lc->blocks_lock, flags);
160 lc->logging_enabled = false;
161 spin_unlock_irqrestore(&lc->blocks_lock, flags);
162 }
163
164 bio_for_each_segment_all(bvec, bio, i)
165 __free_page(bvec->bv_page);
166
167 put_io_block(lc);
168 bio_put(bio);
169}
170
171/*
172 * Meant to be called if there is an error, it will free all the pages
173 * associated with the block.
174 */
175static void free_pending_block(struct log_writes_c *lc,
176 struct pending_block *block)
177{
178 int i;
179
180 for (i = 0; i < block->vec_cnt; i++) {
181 if (block->vecs[i].bv_page)
182 __free_page(block->vecs[i].bv_page);
183 }
184 kfree(block->data);
185 kfree(block);
186 put_pending_block(lc);
187}
188
189static int write_metadata(struct log_writes_c *lc, void *entry,
190 size_t entrylen, void *data, size_t datalen,
191 sector_t sector)
192{
193 struct bio *bio;
194 struct page *page;
195 void *ptr;
196 size_t ret;
197
198 bio = bio_alloc(GFP_KERNEL, 1);
199 if (!bio) {
200 DMERR("Couldn't alloc log bio");
201 goto error;
202 }
203 bio->bi_iter.bi_size = 0;
204 bio->bi_iter.bi_sector = sector;
205 bio->bi_bdev = lc->logdev->bdev;
206 bio->bi_end_io = log_end_io;
207 bio->bi_private = lc;
208 set_bit(BIO_UPTODATE, &bio->bi_flags);
209
210 page = alloc_page(GFP_KERNEL);
211 if (!page) {
212 DMERR("Couldn't alloc log page");
213 bio_put(bio);
214 goto error;
215 }
216
217 ptr = kmap_atomic(page);
218 memcpy(ptr, entry, entrylen);
219 if (datalen)
220 memcpy(ptr + entrylen, data, datalen);
221 memset(ptr + entrylen + datalen, 0,
222 lc->sectorsize - entrylen - datalen);
223 kunmap_atomic(ptr);
224
225 ret = bio_add_page(bio, page, lc->sectorsize, 0);
226 if (ret != lc->sectorsize) {
227 DMERR("Couldn't add page to the log block");
228 goto error_bio;
229 }
230 submit_bio(WRITE, bio);
231 return 0;
232error_bio:
233 bio_put(bio);
234 __free_page(page);
235error:
236 put_io_block(lc);
237 return -1;
238}
239
240static int log_one_block(struct log_writes_c *lc,
241 struct pending_block *block, sector_t sector)
242{
243 struct bio *bio;
244 struct log_write_entry entry;
245 size_t ret;
246 int i;
247
248 entry.sector = cpu_to_le64(block->sector);
249 entry.nr_sectors = cpu_to_le64(block->nr_sectors);
250 entry.flags = cpu_to_le64(block->flags);
251 entry.data_len = cpu_to_le64(block->datalen);
252 if (write_metadata(lc, &entry, sizeof(entry), block->data,
253 block->datalen, sector)) {
254 free_pending_block(lc, block);
255 return -1;
256 }
257
258 if (!block->vec_cnt)
259 goto out;
260 sector++;
261
262 bio = bio_alloc(GFP_KERNEL, block->vec_cnt);
263 if (!bio) {
264 DMERR("Couldn't alloc log bio");
265 goto error;
266 }
267 atomic_inc(&lc->io_blocks);
268 bio->bi_iter.bi_size = 0;
269 bio->bi_iter.bi_sector = sector;
270 bio->bi_bdev = lc->logdev->bdev;
271 bio->bi_end_io = log_end_io;
272 bio->bi_private = lc;
273 set_bit(BIO_UPTODATE, &bio->bi_flags);
274
275 for (i = 0; i < block->vec_cnt; i++) {
276 /*
277 * The page offset is always 0 because we allocate a new page
278 * for every bvec in the original bio for simplicity sake.
279 */
280 ret = bio_add_page(bio, block->vecs[i].bv_page,
281 block->vecs[i].bv_len, 0);
282 if (ret != block->vecs[i].bv_len) {
283 atomic_inc(&lc->io_blocks);
284 submit_bio(WRITE, bio);
285 bio = bio_alloc(GFP_KERNEL, block->vec_cnt - i);
286 if (!bio) {
287 DMERR("Couldn't alloc log bio");
288 goto error;
289 }
290 bio->bi_iter.bi_size = 0;
291 bio->bi_iter.bi_sector = sector;
292 bio->bi_bdev = lc->logdev->bdev;
293 bio->bi_end_io = log_end_io;
294 bio->bi_private = lc;
295 set_bit(BIO_UPTODATE, &bio->bi_flags);
296
297 ret = bio_add_page(bio, block->vecs[i].bv_page,
298 block->vecs[i].bv_len, 0);
299 if (ret != block->vecs[i].bv_len) {
300 DMERR("Couldn't add page on new bio?");
301 bio_put(bio);
302 goto error;
303 }
304 }
305 sector += block->vecs[i].bv_len >> SECTOR_SHIFT;
306 }
307 submit_bio(WRITE, bio);
308out:
309 kfree(block->data);
310 kfree(block);
311 put_pending_block(lc);
312 return 0;
313error:
314 free_pending_block(lc, block);
315 put_io_block(lc);
316 return -1;
317}
318
319static int log_super(struct log_writes_c *lc)
320{
321 struct log_write_super super;
322
323 super.magic = cpu_to_le64(WRITE_LOG_MAGIC);
324 super.version = cpu_to_le64(WRITE_LOG_VERSION);
325 super.nr_entries = cpu_to_le64(lc->logged_entries);
326 super.sectorsize = cpu_to_le32(lc->sectorsize);
327
328 if (write_metadata(lc, &super, sizeof(super), NULL, 0, 0)) {
329 DMERR("Couldn't write super");
330 return -1;
331 }
332
333 return 0;
334}
335
336static inline sector_t logdev_last_sector(struct log_writes_c *lc)
337{
338 return i_size_read(lc->logdev->bdev->bd_inode) >> SECTOR_SHIFT;
339}
340
341static int log_writes_kthread(void *arg)
342{
343 struct log_writes_c *lc = (struct log_writes_c *)arg;
344 sector_t sector = 0;
345
346 while (!kthread_should_stop()) {
347 bool super = false;
348 bool logging_enabled;
349 struct pending_block *block = NULL;
350 int ret;
351
352 spin_lock_irq(&lc->blocks_lock);
353 if (!list_empty(&lc->logging_blocks)) {
354 block = list_first_entry(&lc->logging_blocks,
355 struct pending_block, list);
356 list_del_init(&block->list);
357 if (!lc->logging_enabled)
358 goto next;
359
360 sector = lc->next_sector;
361 if (block->flags & LOG_DISCARD_FLAG)
362 lc->next_sector++;
363 else
364 lc->next_sector += block->nr_sectors + 1;
365
366 /*
367 * Apparently the size of the device may not be known
368 * right away, so handle this properly.
369 */
370 if (!lc->end_sector)
371 lc->end_sector = logdev_last_sector(lc);
372 if (lc->end_sector &&
373 lc->next_sector >= lc->end_sector) {
374 DMERR("Ran out of space on the logdev");
375 lc->logging_enabled = false;
376 goto next;
377 }
378 lc->logged_entries++;
379 atomic_inc(&lc->io_blocks);
380
381 super = (block->flags & (LOG_FUA_FLAG | LOG_MARK_FLAG));
382 if (super)
383 atomic_inc(&lc->io_blocks);
384 }
385next:
386 logging_enabled = lc->logging_enabled;
387 spin_unlock_irq(&lc->blocks_lock);
388 if (block) {
389 if (logging_enabled) {
390 ret = log_one_block(lc, block, sector);
391 if (!ret && super)
392 ret = log_super(lc);
393 if (ret) {
394 spin_lock_irq(&lc->blocks_lock);
395 lc->logging_enabled = false;
396 spin_unlock_irq(&lc->blocks_lock);
397 }
398 } else
399 free_pending_block(lc, block);
400 continue;
401 }
402
403 if (!try_to_freeze()) {
404 set_current_state(TASK_INTERRUPTIBLE);
405 if (!kthread_should_stop() &&
406 !atomic_read(&lc->pending_blocks))
407 schedule();
408 __set_current_state(TASK_RUNNING);
409 }
410 }
411 return 0;
412}
413
414/*
415 * Construct a log-writes mapping:
416 * log-writes <dev_path> <log_dev_path>
417 */
418static int log_writes_ctr(struct dm_target *ti, unsigned int argc, char **argv)
419{
420 struct log_writes_c *lc;
421 struct dm_arg_set as;
422 const char *devname, *logdevname;
423
424 as.argc = argc;
425 as.argv = argv;
426
427 if (argc < 2) {
428 ti->error = "Invalid argument count";
429 return -EINVAL;
430 }
431
432 lc = kzalloc(sizeof(struct log_writes_c), GFP_KERNEL);
433 if (!lc) {
434 ti->error = "Cannot allocate context";
435 return -ENOMEM;
436 }
437 spin_lock_init(&lc->blocks_lock);
438 INIT_LIST_HEAD(&lc->unflushed_blocks);
439 INIT_LIST_HEAD(&lc->logging_blocks);
440 init_waitqueue_head(&lc->wait);
441 lc->sectorsize = 1 << SECTOR_SHIFT;
442 atomic_set(&lc->io_blocks, 0);
443 atomic_set(&lc->pending_blocks, 0);
444
445 devname = dm_shift_arg(&as);
446 if (dm_get_device(ti, devname, dm_table_get_mode(ti->table), &lc->dev)) {
447 ti->error = "Device lookup failed";
448 goto bad;
449 }
450
451 logdevname = dm_shift_arg(&as);
452 if (dm_get_device(ti, logdevname, dm_table_get_mode(ti->table), &lc->logdev)) {
453 ti->error = "Log device lookup failed";
454 dm_put_device(ti, lc->dev);
455 goto bad;
456 }
457
458 lc->log_kthread = kthread_run(log_writes_kthread, lc, "log-write");
459 if (!lc->log_kthread) {
460 ti->error = "Couldn't alloc kthread";
461 dm_put_device(ti, lc->dev);
462 dm_put_device(ti, lc->logdev);
463 goto bad;
464 }
465
466 /* We put the super at sector 0, start logging at sector 1 */
467 lc->next_sector = 1;
468 lc->logging_enabled = true;
469 lc->end_sector = logdev_last_sector(lc);
470 lc->device_supports_discard = true;
471
472 ti->num_flush_bios = 1;
473 ti->flush_supported = true;
474 ti->num_discard_bios = 1;
475 ti->discards_supported = true;
476 ti->per_bio_data_size = sizeof(struct per_bio_data);
477 ti->private = lc;
478 return 0;
479
480bad:
481 kfree(lc);
482 return -EINVAL;
483}
484
485static int log_mark(struct log_writes_c *lc, char *data)
486{
487 struct pending_block *block;
488 size_t maxsize = lc->sectorsize - sizeof(struct log_write_entry);
489
490 block = kzalloc(sizeof(struct pending_block), GFP_KERNEL);
491 if (!block) {
492 DMERR("Error allocating pending block");
493 return -ENOMEM;
494 }
495
496 block->data = kstrndup(data, maxsize, GFP_KERNEL);
497 if (!block->data) {
498 DMERR("Error copying mark data");
499 kfree(block);
500 return -ENOMEM;
501 }
502 atomic_inc(&lc->pending_blocks);
503 block->datalen = strlen(block->data);
504 block->flags |= LOG_MARK_FLAG;
505 spin_lock_irq(&lc->blocks_lock);
506 list_add_tail(&block->list, &lc->logging_blocks);
507 spin_unlock_irq(&lc->blocks_lock);
508 wake_up_process(lc->log_kthread);
509 return 0;
510}
511
512static void log_writes_dtr(struct dm_target *ti)
513{
514 struct log_writes_c *lc = ti->private;
515
516 spin_lock_irq(&lc->blocks_lock);
517 list_splice_init(&lc->unflushed_blocks, &lc->logging_blocks);
518 spin_unlock_irq(&lc->blocks_lock);
519
520 /*
521 * This is just nice to have since it'll update the super to include the
522 * unflushed blocks, if it fails we don't really care.
523 */
524 log_mark(lc, "dm-log-writes-end");
525 wake_up_process(lc->log_kthread);
526 wait_event(lc->wait, !atomic_read(&lc->io_blocks) &&
527 !atomic_read(&lc->pending_blocks));
528 kthread_stop(lc->log_kthread);
529
530 WARN_ON(!list_empty(&lc->logging_blocks));
531 WARN_ON(!list_empty(&lc->unflushed_blocks));
532 dm_put_device(ti, lc->dev);
533 dm_put_device(ti, lc->logdev);
534 kfree(lc);
535}
536
537static void normal_map_bio(struct dm_target *ti, struct bio *bio)
538{
539 struct log_writes_c *lc = ti->private;
540
541 bio->bi_bdev = lc->dev->bdev;
542}
543
544static int log_writes_map(struct dm_target *ti, struct bio *bio)
545{
546 struct log_writes_c *lc = ti->private;
547 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
548 struct pending_block *block;
549 struct bvec_iter iter;
550 struct bio_vec bv;
551 size_t alloc_size;
552 int i = 0;
553 bool flush_bio = (bio->bi_rw & REQ_FLUSH);
554 bool fua_bio = (bio->bi_rw & REQ_FUA);
555 bool discard_bio = (bio->bi_rw & REQ_DISCARD);
556
557 pb->block = NULL;
558
559 /* Don't bother doing anything if logging has been disabled */
560 if (!lc->logging_enabled)
561 goto map_bio;
562
563 /*
564 * Map reads as normal.
565 */
566 if (bio_data_dir(bio) == READ)
567 goto map_bio;
568
569 /* No sectors and not a flush? Don't care */
570 if (!bio_sectors(bio) && !flush_bio)
571 goto map_bio;
572
573 /*
574 * Discards will have bi_size set but there's no actual data, so just
575 * allocate the size of the pending block.
576 */
577 if (discard_bio)
578 alloc_size = sizeof(struct pending_block);
579 else
580 alloc_size = sizeof(struct pending_block) + sizeof(struct bio_vec) * bio_segments(bio);
581
582 block = kzalloc(alloc_size, GFP_NOIO);
583 if (!block) {
584 DMERR("Error allocating pending block");
585 spin_lock_irq(&lc->blocks_lock);
586 lc->logging_enabled = false;
587 spin_unlock_irq(&lc->blocks_lock);
588 return -ENOMEM;
589 }
590 INIT_LIST_HEAD(&block->list);
591 pb->block = block;
592 atomic_inc(&lc->pending_blocks);
593
594 if (flush_bio)
595 block->flags |= LOG_FLUSH_FLAG;
596 if (fua_bio)
597 block->flags |= LOG_FUA_FLAG;
598 if (discard_bio)
599 block->flags |= LOG_DISCARD_FLAG;
600
601 block->sector = bio->bi_iter.bi_sector;
602 block->nr_sectors = bio_sectors(bio);
603
604 /* We don't need the data, just submit */
605 if (discard_bio) {
606 WARN_ON(flush_bio || fua_bio);
607 if (lc->device_supports_discard)
608 goto map_bio;
609 bio_endio(bio, 0);
610 return DM_MAPIO_SUBMITTED;
611 }
612
613 /* Flush bio, splice the unflushed blocks onto this list and submit */
614 if (flush_bio && !bio_sectors(bio)) {
615 spin_lock_irq(&lc->blocks_lock);
616 list_splice_init(&lc->unflushed_blocks, &block->list);
617 spin_unlock_irq(&lc->blocks_lock);
618 goto map_bio;
619 }
620
621 /*
622 * We will write this bio somewhere else way later so we need to copy
623 * the actual contents into new pages so we know the data will always be
624 * there.
625 *
626 * We do this because this could be a bio from O_DIRECT in which case we
627 * can't just hold onto the page until some later point, we have to
628 * manually copy the contents.
629 */
630 bio_for_each_segment(bv, bio, iter) {
631 struct page *page;
632 void *src, *dst;
633
634 page = alloc_page(GFP_NOIO);
635 if (!page) {
636 DMERR("Error allocing page");
637 free_pending_block(lc, block);
638 spin_lock_irq(&lc->blocks_lock);
639 lc->logging_enabled = false;
640 spin_unlock_irq(&lc->blocks_lock);
641 return -ENOMEM;
642 }
643
644 src = kmap_atomic(bv.bv_page);
645 dst = kmap_atomic(page);
646 memcpy(dst, src + bv.bv_offset, bv.bv_len);
647 kunmap_atomic(dst);
648 kunmap_atomic(src);
649 block->vecs[i].bv_page = page;
650 block->vecs[i].bv_len = bv.bv_len;
651 block->vec_cnt++;
652 i++;
653 }
654
655 /* Had a flush with data in it, weird */
656 if (flush_bio) {
657 spin_lock_irq(&lc->blocks_lock);
658 list_splice_init(&lc->unflushed_blocks, &block->list);
659 spin_unlock_irq(&lc->blocks_lock);
660 }
661map_bio:
662 normal_map_bio(ti, bio);
663 return DM_MAPIO_REMAPPED;
664}
665
666static int normal_end_io(struct dm_target *ti, struct bio *bio, int error)
667{
668 struct log_writes_c *lc = ti->private;
669 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
670
671 if (bio_data_dir(bio) == WRITE && pb->block) {
672 struct pending_block *block = pb->block;
673 unsigned long flags;
674
675 spin_lock_irqsave(&lc->blocks_lock, flags);
676 if (block->flags & LOG_FLUSH_FLAG) {
677 list_splice_tail_init(&block->list, &lc->logging_blocks);
678 list_add_tail(&block->list, &lc->logging_blocks);
679 wake_up_process(lc->log_kthread);
680 } else if (block->flags & LOG_FUA_FLAG) {
681 list_add_tail(&block->list, &lc->logging_blocks);
682 wake_up_process(lc->log_kthread);
683 } else
684 list_add_tail(&block->list, &lc->unflushed_blocks);
685 spin_unlock_irqrestore(&lc->blocks_lock, flags);
686 }
687
688 return error;
689}
690
691/*
692 * INFO format: <logged entries> <highest allocated sector>
693 */
694static void log_writes_status(struct dm_target *ti, status_type_t type,
695 unsigned status_flags, char *result,
696 unsigned maxlen)
697{
698 unsigned sz = 0;
699 struct log_writes_c *lc = ti->private;
700
701 switch (type) {
702 case STATUSTYPE_INFO:
703 DMEMIT("%llu %llu", lc->logged_entries,
704 (unsigned long long)lc->next_sector - 1);
705 if (!lc->logging_enabled)
706 DMEMIT(" logging_disabled");
707 break;
708
709 case STATUSTYPE_TABLE:
710 DMEMIT("%s %s", lc->dev->name, lc->logdev->name);
711 break;
712 }
713}
714
715static int log_writes_ioctl(struct dm_target *ti, unsigned int cmd,
716 unsigned long arg)
717{
718 struct log_writes_c *lc = ti->private;
719 struct dm_dev *dev = lc->dev;
720 int r = 0;
721
722 /*
723 * Only pass ioctls through if the device sizes match exactly.
724 */
725 if (ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
726 r = scsi_verify_blk_ioctl(NULL, cmd);
727
728 return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
729}
730
731static int log_writes_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
732 struct bio_vec *biovec, int max_size)
733{
734 struct log_writes_c *lc = ti->private;
735 struct request_queue *q = bdev_get_queue(lc->dev->bdev);
736
737 if (!q->merge_bvec_fn)
738 return max_size;
739
740 bvm->bi_bdev = lc->dev->bdev;
741 bvm->bi_sector = dm_target_offset(ti, bvm->bi_sector);
742
743 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
744}
745
746static int log_writes_iterate_devices(struct dm_target *ti,
747 iterate_devices_callout_fn fn,
748 void *data)
749{
750 struct log_writes_c *lc = ti->private;
751
752 return fn(ti, lc->dev, 0, ti->len, data);
753}
754
755/*
756 * Messages supported:
757 * mark <mark data> - specify the marked data.
758 */
759static int log_writes_message(struct dm_target *ti, unsigned argc, char **argv)
760{
761 int r = -EINVAL;
762 struct log_writes_c *lc = ti->private;
763
764 if (argc != 2) {
765 DMWARN("Invalid log-writes message arguments, expect 2 arguments, got %d", argc);
766 return r;
767 }
768
769 if (!strcasecmp(argv[0], "mark"))
770 r = log_mark(lc, argv[1]);
771 else
772 DMWARN("Unrecognised log writes target message received: %s", argv[0]);
773
774 return r;
775}
776
777static void log_writes_io_hints(struct dm_target *ti, struct queue_limits *limits)
778{
779 struct log_writes_c *lc = ti->private;
780 struct request_queue *q = bdev_get_queue(lc->dev->bdev);
781
782 if (!q || !blk_queue_discard(q)) {
783 lc->device_supports_discard = false;
784 limits->discard_granularity = 1 << SECTOR_SHIFT;
785 limits->max_discard_sectors = (UINT_MAX >> SECTOR_SHIFT);
786 }
787}
788
789static struct target_type log_writes_target = {
790 .name = "log-writes",
791 .version = {1, 0, 0},
792 .module = THIS_MODULE,
793 .ctr = log_writes_ctr,
794 .dtr = log_writes_dtr,
795 .map = log_writes_map,
796 .end_io = normal_end_io,
797 .status = log_writes_status,
798 .ioctl = log_writes_ioctl,
799 .merge = log_writes_merge,
800 .message = log_writes_message,
801 .iterate_devices = log_writes_iterate_devices,
802 .io_hints = log_writes_io_hints,
803};
804
805static int __init dm_log_writes_init(void)
806{
807 int r = dm_register_target(&log_writes_target);
808
809 if (r < 0)
810 DMERR("register failed %d", r);
811
812 return r;
813}
814
815static void __exit dm_log_writes_exit(void)
816{
817 dm_unregister_target(&log_writes_target);
818}
819
820module_init(dm_log_writes_init);
821module_exit(dm_log_writes_exit);
822
823MODULE_DESCRIPTION(DM_NAME " log writes target");
824MODULE_AUTHOR("Josef Bacik <jbacik@fb.com>");
825MODULE_LICENSE("GPL");