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0e9cebe7 JB |
1 | /* |
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 | ||
58 | #define WRITE_LOG_VERSION 1 | |
59 | #define WRITE_LOG_MAGIC 0x6a736677736872 | |
60 | ||
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 | */ | |
77 | struct 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 | */ | |
91 | struct log_write_entry { | |
92 | __le64 sector; | |
93 | __le64 nr_sectors; | |
94 | __le64 flags; | |
95 | __le64 data_len; | |
96 | }; | |
97 | ||
98 | struct 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 | ||
116 | struct 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 | ||
127 | struct per_bio_data { | |
128 | struct pending_block *block; | |
129 | }; | |
130 | ||
131 | static 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 | ||
140 | static 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 | ||
149 | static 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 | */ | |
175 | static 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 | ||
189 | static 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; | |
232 | error_bio: | |
233 | bio_put(bio); | |
234 | __free_page(page); | |
235 | error: | |
236 | put_io_block(lc); | |
237 | return -1; | |
238 | } | |
239 | ||
240 | static 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); | |
308 | out: | |
309 | kfree(block->data); | |
310 | kfree(block); | |
311 | put_pending_block(lc); | |
312 | return 0; | |
313 | error: | |
314 | free_pending_block(lc, block); | |
315 | put_io_block(lc); | |
316 | return -1; | |
317 | } | |
318 | ||
319 | static 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 | ||
336 | static 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 | ||
341 | static 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 | } | |
385 | next: | |
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 | */ | |
418 | static 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 | ||
480 | bad: | |
481 | kfree(lc); | |
482 | return -EINVAL; | |
483 | } | |
484 | ||
485 | static 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 | ||
512 | static 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 | ||
537 | static 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 | ||
544 | static 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 | } | |
661 | map_bio: | |
662 | normal_map_bio(ti, bio); | |
663 | return DM_MAPIO_REMAPPED; | |
664 | } | |
665 | ||
666 | static 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 | */ | |
694 | static 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 | ||
715 | static 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 | ||
731 | static 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 | ||
746 | static 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 | */ | |
759 | static 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 | ||
777 | static 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 | ||
789 | static 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 | ||
805 | static 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 | ||
815 | static void __exit dm_log_writes_exit(void) | |
816 | { | |
817 | dm_unregister_target(&log_writes_target); | |
818 | } | |
819 | ||
820 | module_init(dm_log_writes_init); | |
821 | module_exit(dm_log_writes_exit); | |
822 | ||
823 | MODULE_DESCRIPTION(DM_NAME " log writes target"); | |
824 | MODULE_AUTHOR("Josef Bacik <jbacik@fb.com>"); | |
825 | MODULE_LICENSE("GPL"); |