xref: /linux/drivers/md/raid1.c (revision 2b0cfa6e49566c8fa6759734cf821aa6e8271a9e)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * raid1.c : Multiple Devices driver for Linux
4  *
5  * Copyright (C) 1999, 2000, 2001 Ingo Molnar, Red Hat
6  *
7  * Copyright (C) 1996, 1997, 1998 Ingo Molnar, Miguel de Icaza, Gadi Oxman
8  *
9  * RAID-1 management functions.
10  *
11  * Better read-balancing code written by Mika Kuoppala <miku@iki.fi>, 2000
12  *
13  * Fixes to reconstruction by Jakob Østergaard" <jakob@ostenfeld.dk>
14  * Various fixes by Neil Brown <neilb@cse.unsw.edu.au>
15  *
16  * Changes by Peter T. Breuer <ptb@it.uc3m.es> 31/1/2003 to support
17  * bitmapped intelligence in resync:
18  *
19  *      - bitmap marked during normal i/o
20  *      - bitmap used to skip nondirty blocks during sync
21  *
22  * Additions to bitmap code, (C) 2003-2004 Paul Clements, SteelEye Technology:
23  * - persistent bitmap code
24  */
25 
26 #include <linux/slab.h>
27 #include <linux/delay.h>
28 #include <linux/blkdev.h>
29 #include <linux/module.h>
30 #include <linux/seq_file.h>
31 #include <linux/ratelimit.h>
32 #include <linux/interval_tree_generic.h>
33 
34 #include <trace/events/block.h>
35 
36 #include "md.h"
37 #include "raid1.h"
38 #include "md-bitmap.h"
39 
40 #define UNSUPPORTED_MDDEV_FLAGS		\
41 	((1L << MD_HAS_JOURNAL) |	\
42 	 (1L << MD_JOURNAL_CLEAN) |	\
43 	 (1L << MD_HAS_PPL) |		\
44 	 (1L << MD_HAS_MULTIPLE_PPLS))
45 
46 static void allow_barrier(struct r1conf *conf, sector_t sector_nr);
47 static void lower_barrier(struct r1conf *conf, sector_t sector_nr);
48 
49 #define raid1_log(md, fmt, args...)				\
50 	do { if ((md)->queue) blk_add_trace_msg((md)->queue, "raid1 " fmt, ##args); } while (0)
51 
52 #define RAID_1_10_NAME "raid1"
53 #include "raid1-10.c"
54 
55 #define START(node) ((node)->start)
56 #define LAST(node) ((node)->last)
57 INTERVAL_TREE_DEFINE(struct serial_info, node, sector_t, _subtree_last,
58 		     START, LAST, static inline, raid1_rb);
59 
60 static int check_and_add_serial(struct md_rdev *rdev, struct r1bio *r1_bio,
61 				struct serial_info *si, int idx)
62 {
63 	unsigned long flags;
64 	int ret = 0;
65 	sector_t lo = r1_bio->sector;
66 	sector_t hi = lo + r1_bio->sectors;
67 	struct serial_in_rdev *serial = &rdev->serial[idx];
68 
69 	spin_lock_irqsave(&serial->serial_lock, flags);
70 	/* collision happened */
71 	if (raid1_rb_iter_first(&serial->serial_rb, lo, hi))
72 		ret = -EBUSY;
73 	else {
74 		si->start = lo;
75 		si->last = hi;
76 		raid1_rb_insert(si, &serial->serial_rb);
77 	}
78 	spin_unlock_irqrestore(&serial->serial_lock, flags);
79 
80 	return ret;
81 }
82 
83 static void wait_for_serialization(struct md_rdev *rdev, struct r1bio *r1_bio)
84 {
85 	struct mddev *mddev = rdev->mddev;
86 	struct serial_info *si;
87 	int idx = sector_to_idx(r1_bio->sector);
88 	struct serial_in_rdev *serial = &rdev->serial[idx];
89 
90 	if (WARN_ON(!mddev->serial_info_pool))
91 		return;
92 	si = mempool_alloc(mddev->serial_info_pool, GFP_NOIO);
93 	wait_event(serial->serial_io_wait,
94 		   check_and_add_serial(rdev, r1_bio, si, idx) == 0);
95 }
96 
97 static void remove_serial(struct md_rdev *rdev, sector_t lo, sector_t hi)
98 {
99 	struct serial_info *si;
100 	unsigned long flags;
101 	int found = 0;
102 	struct mddev *mddev = rdev->mddev;
103 	int idx = sector_to_idx(lo);
104 	struct serial_in_rdev *serial = &rdev->serial[idx];
105 
106 	spin_lock_irqsave(&serial->serial_lock, flags);
107 	for (si = raid1_rb_iter_first(&serial->serial_rb, lo, hi);
108 	     si; si = raid1_rb_iter_next(si, lo, hi)) {
109 		if (si->start == lo && si->last == hi) {
110 			raid1_rb_remove(si, &serial->serial_rb);
111 			mempool_free(si, mddev->serial_info_pool);
112 			found = 1;
113 			break;
114 		}
115 	}
116 	if (!found)
117 		WARN(1, "The write IO is not recorded for serialization\n");
118 	spin_unlock_irqrestore(&serial->serial_lock, flags);
119 	wake_up(&serial->serial_io_wait);
120 }
121 
122 /*
123  * for resync bio, r1bio pointer can be retrieved from the per-bio
124  * 'struct resync_pages'.
125  */
126 static inline struct r1bio *get_resync_r1bio(struct bio *bio)
127 {
128 	return get_resync_pages(bio)->raid_bio;
129 }
130 
131 static void * r1bio_pool_alloc(gfp_t gfp_flags, void *data)
132 {
133 	struct pool_info *pi = data;
134 	int size = offsetof(struct r1bio, bios[pi->raid_disks]);
135 
136 	/* allocate a r1bio with room for raid_disks entries in the bios array */
137 	return kzalloc(size, gfp_flags);
138 }
139 
140 #define RESYNC_DEPTH 32
141 #define RESYNC_SECTORS (RESYNC_BLOCK_SIZE >> 9)
142 #define RESYNC_WINDOW (RESYNC_BLOCK_SIZE * RESYNC_DEPTH)
143 #define RESYNC_WINDOW_SECTORS (RESYNC_WINDOW >> 9)
144 #define CLUSTER_RESYNC_WINDOW (16 * RESYNC_WINDOW)
145 #define CLUSTER_RESYNC_WINDOW_SECTORS (CLUSTER_RESYNC_WINDOW >> 9)
146 
147 static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
148 {
149 	struct pool_info *pi = data;
150 	struct r1bio *r1_bio;
151 	struct bio *bio;
152 	int need_pages;
153 	int j;
154 	struct resync_pages *rps;
155 
156 	r1_bio = r1bio_pool_alloc(gfp_flags, pi);
157 	if (!r1_bio)
158 		return NULL;
159 
160 	rps = kmalloc_array(pi->raid_disks, sizeof(struct resync_pages),
161 			    gfp_flags);
162 	if (!rps)
163 		goto out_free_r1bio;
164 
165 	/*
166 	 * Allocate bios : 1 for reading, n-1 for writing
167 	 */
168 	for (j = pi->raid_disks ; j-- ; ) {
169 		bio = bio_kmalloc(RESYNC_PAGES, gfp_flags);
170 		if (!bio)
171 			goto out_free_bio;
172 		bio_init(bio, NULL, bio->bi_inline_vecs, RESYNC_PAGES, 0);
173 		r1_bio->bios[j] = bio;
174 	}
175 	/*
176 	 * Allocate RESYNC_PAGES data pages and attach them to
177 	 * the first bio.
178 	 * If this is a user-requested check/repair, allocate
179 	 * RESYNC_PAGES for each bio.
180 	 */
181 	if (test_bit(MD_RECOVERY_REQUESTED, &pi->mddev->recovery))
182 		need_pages = pi->raid_disks;
183 	else
184 		need_pages = 1;
185 	for (j = 0; j < pi->raid_disks; j++) {
186 		struct resync_pages *rp = &rps[j];
187 
188 		bio = r1_bio->bios[j];
189 
190 		if (j < need_pages) {
191 			if (resync_alloc_pages(rp, gfp_flags))
192 				goto out_free_pages;
193 		} else {
194 			memcpy(rp, &rps[0], sizeof(*rp));
195 			resync_get_all_pages(rp);
196 		}
197 
198 		rp->raid_bio = r1_bio;
199 		bio->bi_private = rp;
200 	}
201 
202 	r1_bio->master_bio = NULL;
203 
204 	return r1_bio;
205 
206 out_free_pages:
207 	while (--j >= 0)
208 		resync_free_pages(&rps[j]);
209 
210 out_free_bio:
211 	while (++j < pi->raid_disks) {
212 		bio_uninit(r1_bio->bios[j]);
213 		kfree(r1_bio->bios[j]);
214 	}
215 	kfree(rps);
216 
217 out_free_r1bio:
218 	rbio_pool_free(r1_bio, data);
219 	return NULL;
220 }
221 
222 static void r1buf_pool_free(void *__r1_bio, void *data)
223 {
224 	struct pool_info *pi = data;
225 	int i;
226 	struct r1bio *r1bio = __r1_bio;
227 	struct resync_pages *rp = NULL;
228 
229 	for (i = pi->raid_disks; i--; ) {
230 		rp = get_resync_pages(r1bio->bios[i]);
231 		resync_free_pages(rp);
232 		bio_uninit(r1bio->bios[i]);
233 		kfree(r1bio->bios[i]);
234 	}
235 
236 	/* resync pages array stored in the 1st bio's .bi_private */
237 	kfree(rp);
238 
239 	rbio_pool_free(r1bio, data);
240 }
241 
242 static void put_all_bios(struct r1conf *conf, struct r1bio *r1_bio)
243 {
244 	int i;
245 
246 	for (i = 0; i < conf->raid_disks * 2; i++) {
247 		struct bio **bio = r1_bio->bios + i;
248 		if (!BIO_SPECIAL(*bio))
249 			bio_put(*bio);
250 		*bio = NULL;
251 	}
252 }
253 
254 static void free_r1bio(struct r1bio *r1_bio)
255 {
256 	struct r1conf *conf = r1_bio->mddev->private;
257 
258 	put_all_bios(conf, r1_bio);
259 	mempool_free(r1_bio, &conf->r1bio_pool);
260 }
261 
262 static void put_buf(struct r1bio *r1_bio)
263 {
264 	struct r1conf *conf = r1_bio->mddev->private;
265 	sector_t sect = r1_bio->sector;
266 	int i;
267 
268 	for (i = 0; i < conf->raid_disks * 2; i++) {
269 		struct bio *bio = r1_bio->bios[i];
270 		if (bio->bi_end_io)
271 			rdev_dec_pending(conf->mirrors[i].rdev, r1_bio->mddev);
272 	}
273 
274 	mempool_free(r1_bio, &conf->r1buf_pool);
275 
276 	lower_barrier(conf, sect);
277 }
278 
279 static void reschedule_retry(struct r1bio *r1_bio)
280 {
281 	unsigned long flags;
282 	struct mddev *mddev = r1_bio->mddev;
283 	struct r1conf *conf = mddev->private;
284 	int idx;
285 
286 	idx = sector_to_idx(r1_bio->sector);
287 	spin_lock_irqsave(&conf->device_lock, flags);
288 	list_add(&r1_bio->retry_list, &conf->retry_list);
289 	atomic_inc(&conf->nr_queued[idx]);
290 	spin_unlock_irqrestore(&conf->device_lock, flags);
291 
292 	wake_up(&conf->wait_barrier);
293 	md_wakeup_thread(mddev->thread);
294 }
295 
296 /*
297  * raid_end_bio_io() is called when we have finished servicing a mirrored
298  * operation and are ready to return a success/failure code to the buffer
299  * cache layer.
300  */
301 static void call_bio_endio(struct r1bio *r1_bio)
302 {
303 	struct bio *bio = r1_bio->master_bio;
304 
305 	if (!test_bit(R1BIO_Uptodate, &r1_bio->state))
306 		bio->bi_status = BLK_STS_IOERR;
307 
308 	bio_endio(bio);
309 }
310 
311 static void raid_end_bio_io(struct r1bio *r1_bio)
312 {
313 	struct bio *bio = r1_bio->master_bio;
314 	struct r1conf *conf = r1_bio->mddev->private;
315 	sector_t sector = r1_bio->sector;
316 
317 	/* if nobody has done the final endio yet, do it now */
318 	if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
319 		pr_debug("raid1: sync end %s on sectors %llu-%llu\n",
320 			 (bio_data_dir(bio) == WRITE) ? "write" : "read",
321 			 (unsigned long long) bio->bi_iter.bi_sector,
322 			 (unsigned long long) bio_end_sector(bio) - 1);
323 
324 		call_bio_endio(r1_bio);
325 	}
326 
327 	free_r1bio(r1_bio);
328 	/*
329 	 * Wake up any possible resync thread that waits for the device
330 	 * to go idle.  All I/Os, even write-behind writes, are done.
331 	 */
332 	allow_barrier(conf, sector);
333 }
334 
335 /*
336  * Update disk head position estimator based on IRQ completion info.
337  */
338 static inline void update_head_pos(int disk, struct r1bio *r1_bio)
339 {
340 	struct r1conf *conf = r1_bio->mddev->private;
341 
342 	conf->mirrors[disk].head_position =
343 		r1_bio->sector + (r1_bio->sectors);
344 }
345 
346 /*
347  * Find the disk number which triggered given bio
348  */
349 static int find_bio_disk(struct r1bio *r1_bio, struct bio *bio)
350 {
351 	int mirror;
352 	struct r1conf *conf = r1_bio->mddev->private;
353 	int raid_disks = conf->raid_disks;
354 
355 	for (mirror = 0; mirror < raid_disks * 2; mirror++)
356 		if (r1_bio->bios[mirror] == bio)
357 			break;
358 
359 	BUG_ON(mirror == raid_disks * 2);
360 	update_head_pos(mirror, r1_bio);
361 
362 	return mirror;
363 }
364 
365 static void raid1_end_read_request(struct bio *bio)
366 {
367 	int uptodate = !bio->bi_status;
368 	struct r1bio *r1_bio = bio->bi_private;
369 	struct r1conf *conf = r1_bio->mddev->private;
370 	struct md_rdev *rdev = conf->mirrors[r1_bio->read_disk].rdev;
371 
372 	/*
373 	 * this branch is our 'one mirror IO has finished' event handler:
374 	 */
375 	update_head_pos(r1_bio->read_disk, r1_bio);
376 
377 	if (uptodate)
378 		set_bit(R1BIO_Uptodate, &r1_bio->state);
379 	else if (test_bit(FailFast, &rdev->flags) &&
380 		 test_bit(R1BIO_FailFast, &r1_bio->state))
381 		/* This was a fail-fast read so we definitely
382 		 * want to retry */
383 		;
384 	else {
385 		/* If all other devices have failed, we want to return
386 		 * the error upwards rather than fail the last device.
387 		 * Here we redefine "uptodate" to mean "Don't want to retry"
388 		 */
389 		unsigned long flags;
390 		spin_lock_irqsave(&conf->device_lock, flags);
391 		if (r1_bio->mddev->degraded == conf->raid_disks ||
392 		    (r1_bio->mddev->degraded == conf->raid_disks-1 &&
393 		     test_bit(In_sync, &rdev->flags)))
394 			uptodate = 1;
395 		spin_unlock_irqrestore(&conf->device_lock, flags);
396 	}
397 
398 	if (uptodate) {
399 		raid_end_bio_io(r1_bio);
400 		rdev_dec_pending(rdev, conf->mddev);
401 	} else {
402 		/*
403 		 * oops, read error:
404 		 */
405 		pr_err_ratelimited("md/raid1:%s: %pg: rescheduling sector %llu\n",
406 				   mdname(conf->mddev),
407 				   rdev->bdev,
408 				   (unsigned long long)r1_bio->sector);
409 		set_bit(R1BIO_ReadError, &r1_bio->state);
410 		reschedule_retry(r1_bio);
411 		/* don't drop the reference on read_disk yet */
412 	}
413 }
414 
415 static void close_write(struct r1bio *r1_bio)
416 {
417 	/* it really is the end of this request */
418 	if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
419 		bio_free_pages(r1_bio->behind_master_bio);
420 		bio_put(r1_bio->behind_master_bio);
421 		r1_bio->behind_master_bio = NULL;
422 	}
423 	/* clear the bitmap if all writes complete successfully */
424 	md_bitmap_endwrite(r1_bio->mddev->bitmap, r1_bio->sector,
425 			   r1_bio->sectors,
426 			   !test_bit(R1BIO_Degraded, &r1_bio->state),
427 			   test_bit(R1BIO_BehindIO, &r1_bio->state));
428 	md_write_end(r1_bio->mddev);
429 }
430 
431 static void r1_bio_write_done(struct r1bio *r1_bio)
432 {
433 	if (!atomic_dec_and_test(&r1_bio->remaining))
434 		return;
435 
436 	if (test_bit(R1BIO_WriteError, &r1_bio->state))
437 		reschedule_retry(r1_bio);
438 	else {
439 		close_write(r1_bio);
440 		if (test_bit(R1BIO_MadeGood, &r1_bio->state))
441 			reschedule_retry(r1_bio);
442 		else
443 			raid_end_bio_io(r1_bio);
444 	}
445 }
446 
447 static void raid1_end_write_request(struct bio *bio)
448 {
449 	struct r1bio *r1_bio = bio->bi_private;
450 	int behind = test_bit(R1BIO_BehindIO, &r1_bio->state);
451 	struct r1conf *conf = r1_bio->mddev->private;
452 	struct bio *to_put = NULL;
453 	int mirror = find_bio_disk(r1_bio, bio);
454 	struct md_rdev *rdev = conf->mirrors[mirror].rdev;
455 	bool discard_error;
456 	sector_t lo = r1_bio->sector;
457 	sector_t hi = r1_bio->sector + r1_bio->sectors;
458 
459 	discard_error = bio->bi_status && bio_op(bio) == REQ_OP_DISCARD;
460 
461 	/*
462 	 * 'one mirror IO has finished' event handler:
463 	 */
464 	if (bio->bi_status && !discard_error) {
465 		set_bit(WriteErrorSeen,	&rdev->flags);
466 		if (!test_and_set_bit(WantReplacement, &rdev->flags))
467 			set_bit(MD_RECOVERY_NEEDED, &
468 				conf->mddev->recovery);
469 
470 		if (test_bit(FailFast, &rdev->flags) &&
471 		    (bio->bi_opf & MD_FAILFAST) &&
472 		    /* We never try FailFast to WriteMostly devices */
473 		    !test_bit(WriteMostly, &rdev->flags)) {
474 			md_error(r1_bio->mddev, rdev);
475 		}
476 
477 		/*
478 		 * When the device is faulty, it is not necessary to
479 		 * handle write error.
480 		 */
481 		if (!test_bit(Faulty, &rdev->flags))
482 			set_bit(R1BIO_WriteError, &r1_bio->state);
483 		else {
484 			/* Fail the request */
485 			set_bit(R1BIO_Degraded, &r1_bio->state);
486 			/* Finished with this branch */
487 			r1_bio->bios[mirror] = NULL;
488 			to_put = bio;
489 		}
490 	} else {
491 		/*
492 		 * Set R1BIO_Uptodate in our master bio, so that we
493 		 * will return a good error code for to the higher
494 		 * levels even if IO on some other mirrored buffer
495 		 * fails.
496 		 *
497 		 * The 'master' represents the composite IO operation
498 		 * to user-side. So if something waits for IO, then it
499 		 * will wait for the 'master' bio.
500 		 */
501 		sector_t first_bad;
502 		int bad_sectors;
503 
504 		r1_bio->bios[mirror] = NULL;
505 		to_put = bio;
506 		/*
507 		 * Do not set R1BIO_Uptodate if the current device is
508 		 * rebuilding or Faulty. This is because we cannot use
509 		 * such device for properly reading the data back (we could
510 		 * potentially use it, if the current write would have felt
511 		 * before rdev->recovery_offset, but for simplicity we don't
512 		 * check this here.
513 		 */
514 		if (test_bit(In_sync, &rdev->flags) &&
515 		    !test_bit(Faulty, &rdev->flags))
516 			set_bit(R1BIO_Uptodate, &r1_bio->state);
517 
518 		/* Maybe we can clear some bad blocks. */
519 		if (is_badblock(rdev, r1_bio->sector, r1_bio->sectors,
520 				&first_bad, &bad_sectors) && !discard_error) {
521 			r1_bio->bios[mirror] = IO_MADE_GOOD;
522 			set_bit(R1BIO_MadeGood, &r1_bio->state);
523 		}
524 	}
525 
526 	if (behind) {
527 		if (test_bit(CollisionCheck, &rdev->flags))
528 			remove_serial(rdev, lo, hi);
529 		if (test_bit(WriteMostly, &rdev->flags))
530 			atomic_dec(&r1_bio->behind_remaining);
531 
532 		/*
533 		 * In behind mode, we ACK the master bio once the I/O
534 		 * has safely reached all non-writemostly
535 		 * disks. Setting the Returned bit ensures that this
536 		 * gets done only once -- we don't ever want to return
537 		 * -EIO here, instead we'll wait
538 		 */
539 		if (atomic_read(&r1_bio->behind_remaining) >= (atomic_read(&r1_bio->remaining)-1) &&
540 		    test_bit(R1BIO_Uptodate, &r1_bio->state)) {
541 			/* Maybe we can return now */
542 			if (!test_and_set_bit(R1BIO_Returned, &r1_bio->state)) {
543 				struct bio *mbio = r1_bio->master_bio;
544 				pr_debug("raid1: behind end write sectors"
545 					 " %llu-%llu\n",
546 					 (unsigned long long) mbio->bi_iter.bi_sector,
547 					 (unsigned long long) bio_end_sector(mbio) - 1);
548 				call_bio_endio(r1_bio);
549 			}
550 		}
551 	} else if (rdev->mddev->serialize_policy)
552 		remove_serial(rdev, lo, hi);
553 	if (r1_bio->bios[mirror] == NULL)
554 		rdev_dec_pending(rdev, conf->mddev);
555 
556 	/*
557 	 * Let's see if all mirrored write operations have finished
558 	 * already.
559 	 */
560 	r1_bio_write_done(r1_bio);
561 
562 	if (to_put)
563 		bio_put(to_put);
564 }
565 
566 static sector_t align_to_barrier_unit_end(sector_t start_sector,
567 					  sector_t sectors)
568 {
569 	sector_t len;
570 
571 	WARN_ON(sectors == 0);
572 	/*
573 	 * len is the number of sectors from start_sector to end of the
574 	 * barrier unit which start_sector belongs to.
575 	 */
576 	len = round_up(start_sector + 1, BARRIER_UNIT_SECTOR_SIZE) -
577 	      start_sector;
578 
579 	if (len > sectors)
580 		len = sectors;
581 
582 	return len;
583 }
584 
585 /*
586  * This routine returns the disk from which the requested read should
587  * be done. There is a per-array 'next expected sequential IO' sector
588  * number - if this matches on the next IO then we use the last disk.
589  * There is also a per-disk 'last know head position' sector that is
590  * maintained from IRQ contexts, both the normal and the resync IO
591  * completion handlers update this position correctly. If there is no
592  * perfect sequential match then we pick the disk whose head is closest.
593  *
594  * If there are 2 mirrors in the same 2 devices, performance degrades
595  * because position is mirror, not device based.
596  *
597  * The rdev for the device selected will have nr_pending incremented.
598  */
599 static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sectors)
600 {
601 	const sector_t this_sector = r1_bio->sector;
602 	int sectors;
603 	int best_good_sectors;
604 	int best_disk, best_dist_disk, best_pending_disk;
605 	int has_nonrot_disk;
606 	int disk;
607 	sector_t best_dist;
608 	unsigned int min_pending;
609 	struct md_rdev *rdev;
610 	int choose_first;
611 	int choose_next_idle;
612 
613 	/*
614 	 * Check if we can balance. We can balance on the whole
615 	 * device if no resync is going on, or below the resync window.
616 	 * We take the first readable disk when above the resync window.
617 	 */
618  retry:
619 	sectors = r1_bio->sectors;
620 	best_disk = -1;
621 	best_dist_disk = -1;
622 	best_dist = MaxSector;
623 	best_pending_disk = -1;
624 	min_pending = UINT_MAX;
625 	best_good_sectors = 0;
626 	has_nonrot_disk = 0;
627 	choose_next_idle = 0;
628 	clear_bit(R1BIO_FailFast, &r1_bio->state);
629 
630 	if ((conf->mddev->recovery_cp < this_sector + sectors) ||
631 	    (mddev_is_clustered(conf->mddev) &&
632 	    md_cluster_ops->area_resyncing(conf->mddev, READ, this_sector,
633 		    this_sector + sectors)))
634 		choose_first = 1;
635 	else
636 		choose_first = 0;
637 
638 	for (disk = 0 ; disk < conf->raid_disks * 2 ; disk++) {
639 		sector_t dist;
640 		sector_t first_bad;
641 		int bad_sectors;
642 		unsigned int pending;
643 		bool nonrot;
644 
645 		rdev = conf->mirrors[disk].rdev;
646 		if (r1_bio->bios[disk] == IO_BLOCKED
647 		    || rdev == NULL
648 		    || test_bit(Faulty, &rdev->flags))
649 			continue;
650 		if (!test_bit(In_sync, &rdev->flags) &&
651 		    rdev->recovery_offset < this_sector + sectors)
652 			continue;
653 		if (test_bit(WriteMostly, &rdev->flags)) {
654 			/* Don't balance among write-mostly, just
655 			 * use the first as a last resort */
656 			if (best_dist_disk < 0) {
657 				if (is_badblock(rdev, this_sector, sectors,
658 						&first_bad, &bad_sectors)) {
659 					if (first_bad <= this_sector)
660 						/* Cannot use this */
661 						continue;
662 					best_good_sectors = first_bad - this_sector;
663 				} else
664 					best_good_sectors = sectors;
665 				best_dist_disk = disk;
666 				best_pending_disk = disk;
667 			}
668 			continue;
669 		}
670 		/* This is a reasonable device to use.  It might
671 		 * even be best.
672 		 */
673 		if (is_badblock(rdev, this_sector, sectors,
674 				&first_bad, &bad_sectors)) {
675 			if (best_dist < MaxSector)
676 				/* already have a better device */
677 				continue;
678 			if (first_bad <= this_sector) {
679 				/* cannot read here. If this is the 'primary'
680 				 * device, then we must not read beyond
681 				 * bad_sectors from another device..
682 				 */
683 				bad_sectors -= (this_sector - first_bad);
684 				if (choose_first && sectors > bad_sectors)
685 					sectors = bad_sectors;
686 				if (best_good_sectors > sectors)
687 					best_good_sectors = sectors;
688 
689 			} else {
690 				sector_t good_sectors = first_bad - this_sector;
691 				if (good_sectors > best_good_sectors) {
692 					best_good_sectors = good_sectors;
693 					best_disk = disk;
694 				}
695 				if (choose_first)
696 					break;
697 			}
698 			continue;
699 		} else {
700 			if ((sectors > best_good_sectors) && (best_disk >= 0))
701 				best_disk = -1;
702 			best_good_sectors = sectors;
703 		}
704 
705 		if (best_disk >= 0)
706 			/* At least two disks to choose from so failfast is OK */
707 			set_bit(R1BIO_FailFast, &r1_bio->state);
708 
709 		nonrot = bdev_nonrot(rdev->bdev);
710 		has_nonrot_disk |= nonrot;
711 		pending = atomic_read(&rdev->nr_pending);
712 		dist = abs(this_sector - conf->mirrors[disk].head_position);
713 		if (choose_first) {
714 			best_disk = disk;
715 			break;
716 		}
717 		/* Don't change to another disk for sequential reads */
718 		if (conf->mirrors[disk].next_seq_sect == this_sector
719 		    || dist == 0) {
720 			int opt_iosize = bdev_io_opt(rdev->bdev) >> 9;
721 			struct raid1_info *mirror = &conf->mirrors[disk];
722 
723 			best_disk = disk;
724 			/*
725 			 * If buffered sequential IO size exceeds optimal
726 			 * iosize, check if there is idle disk. If yes, choose
727 			 * the idle disk. read_balance could already choose an
728 			 * idle disk before noticing it's a sequential IO in
729 			 * this disk. This doesn't matter because this disk
730 			 * will idle, next time it will be utilized after the
731 			 * first disk has IO size exceeds optimal iosize. In
732 			 * this way, iosize of the first disk will be optimal
733 			 * iosize at least. iosize of the second disk might be
734 			 * small, but not a big deal since when the second disk
735 			 * starts IO, the first disk is likely still busy.
736 			 */
737 			if (nonrot && opt_iosize > 0 &&
738 			    mirror->seq_start != MaxSector &&
739 			    mirror->next_seq_sect > opt_iosize &&
740 			    mirror->next_seq_sect - opt_iosize >=
741 			    mirror->seq_start) {
742 				choose_next_idle = 1;
743 				continue;
744 			}
745 			break;
746 		}
747 
748 		if (choose_next_idle)
749 			continue;
750 
751 		if (min_pending > pending) {
752 			min_pending = pending;
753 			best_pending_disk = disk;
754 		}
755 
756 		if (dist < best_dist) {
757 			best_dist = dist;
758 			best_dist_disk = disk;
759 		}
760 	}
761 
762 	/*
763 	 * If all disks are rotational, choose the closest disk. If any disk is
764 	 * non-rotational, choose the disk with less pending request even the
765 	 * disk is rotational, which might/might not be optimal for raids with
766 	 * mixed ratation/non-rotational disks depending on workload.
767 	 */
768 	if (best_disk == -1) {
769 		if (has_nonrot_disk || min_pending == 0)
770 			best_disk = best_pending_disk;
771 		else
772 			best_disk = best_dist_disk;
773 	}
774 
775 	if (best_disk >= 0) {
776 		rdev = conf->mirrors[best_disk].rdev;
777 		if (!rdev)
778 			goto retry;
779 		atomic_inc(&rdev->nr_pending);
780 		sectors = best_good_sectors;
781 
782 		if (conf->mirrors[best_disk].next_seq_sect != this_sector)
783 			conf->mirrors[best_disk].seq_start = this_sector;
784 
785 		conf->mirrors[best_disk].next_seq_sect = this_sector + sectors;
786 	}
787 	*max_sectors = sectors;
788 
789 	return best_disk;
790 }
791 
792 static void wake_up_barrier(struct r1conf *conf)
793 {
794 	if (wq_has_sleeper(&conf->wait_barrier))
795 		wake_up(&conf->wait_barrier);
796 }
797 
798 static void flush_bio_list(struct r1conf *conf, struct bio *bio)
799 {
800 	/* flush any pending bitmap writes to disk before proceeding w/ I/O */
801 	raid1_prepare_flush_writes(conf->mddev->bitmap);
802 	wake_up_barrier(conf);
803 
804 	while (bio) { /* submit pending writes */
805 		struct bio *next = bio->bi_next;
806 
807 		raid1_submit_write(bio);
808 		bio = next;
809 		cond_resched();
810 	}
811 }
812 
813 static void flush_pending_writes(struct r1conf *conf)
814 {
815 	/* Any writes that have been queued but are awaiting
816 	 * bitmap updates get flushed here.
817 	 */
818 	spin_lock_irq(&conf->device_lock);
819 
820 	if (conf->pending_bio_list.head) {
821 		struct blk_plug plug;
822 		struct bio *bio;
823 
824 		bio = bio_list_get(&conf->pending_bio_list);
825 		spin_unlock_irq(&conf->device_lock);
826 
827 		/*
828 		 * As this is called in a wait_event() loop (see freeze_array),
829 		 * current->state might be TASK_UNINTERRUPTIBLE which will
830 		 * cause a warning when we prepare to wait again.  As it is
831 		 * rare that this path is taken, it is perfectly safe to force
832 		 * us to go around the wait_event() loop again, so the warning
833 		 * is a false-positive.  Silence the warning by resetting
834 		 * thread state
835 		 */
836 		__set_current_state(TASK_RUNNING);
837 		blk_start_plug(&plug);
838 		flush_bio_list(conf, bio);
839 		blk_finish_plug(&plug);
840 	} else
841 		spin_unlock_irq(&conf->device_lock);
842 }
843 
844 /* Barriers....
845  * Sometimes we need to suspend IO while we do something else,
846  * either some resync/recovery, or reconfigure the array.
847  * To do this we raise a 'barrier'.
848  * The 'barrier' is a counter that can be raised multiple times
849  * to count how many activities are happening which preclude
850  * normal IO.
851  * We can only raise the barrier if there is no pending IO.
852  * i.e. if nr_pending == 0.
853  * We choose only to raise the barrier if no-one is waiting for the
854  * barrier to go down.  This means that as soon as an IO request
855  * is ready, no other operations which require a barrier will start
856  * until the IO request has had a chance.
857  *
858  * So: regular IO calls 'wait_barrier'.  When that returns there
859  *    is no backgroup IO happening,  It must arrange to call
860  *    allow_barrier when it has finished its IO.
861  * backgroup IO calls must call raise_barrier.  Once that returns
862  *    there is no normal IO happeing.  It must arrange to call
863  *    lower_barrier when the particular background IO completes.
864  *
865  * If resync/recovery is interrupted, returns -EINTR;
866  * Otherwise, returns 0.
867  */
868 static int raise_barrier(struct r1conf *conf, sector_t sector_nr)
869 {
870 	int idx = sector_to_idx(sector_nr);
871 
872 	spin_lock_irq(&conf->resync_lock);
873 
874 	/* Wait until no block IO is waiting */
875 	wait_event_lock_irq(conf->wait_barrier,
876 			    !atomic_read(&conf->nr_waiting[idx]),
877 			    conf->resync_lock);
878 
879 	/* block any new IO from starting */
880 	atomic_inc(&conf->barrier[idx]);
881 	/*
882 	 * In raise_barrier() we firstly increase conf->barrier[idx] then
883 	 * check conf->nr_pending[idx]. In _wait_barrier() we firstly
884 	 * increase conf->nr_pending[idx] then check conf->barrier[idx].
885 	 * A memory barrier here to make sure conf->nr_pending[idx] won't
886 	 * be fetched before conf->barrier[idx] is increased. Otherwise
887 	 * there will be a race between raise_barrier() and _wait_barrier().
888 	 */
889 	smp_mb__after_atomic();
890 
891 	/* For these conditions we must wait:
892 	 * A: while the array is in frozen state
893 	 * B: while conf->nr_pending[idx] is not 0, meaning regular I/O
894 	 *    existing in corresponding I/O barrier bucket.
895 	 * C: while conf->barrier[idx] >= RESYNC_DEPTH, meaning reaches
896 	 *    max resync count which allowed on current I/O barrier bucket.
897 	 */
898 	wait_event_lock_irq(conf->wait_barrier,
899 			    (!conf->array_frozen &&
900 			     !atomic_read(&conf->nr_pending[idx]) &&
901 			     atomic_read(&conf->barrier[idx]) < RESYNC_DEPTH) ||
902 				test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery),
903 			    conf->resync_lock);
904 
905 	if (test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
906 		atomic_dec(&conf->barrier[idx]);
907 		spin_unlock_irq(&conf->resync_lock);
908 		wake_up(&conf->wait_barrier);
909 		return -EINTR;
910 	}
911 
912 	atomic_inc(&conf->nr_sync_pending);
913 	spin_unlock_irq(&conf->resync_lock);
914 
915 	return 0;
916 }
917 
918 static void lower_barrier(struct r1conf *conf, sector_t sector_nr)
919 {
920 	int idx = sector_to_idx(sector_nr);
921 
922 	BUG_ON(atomic_read(&conf->barrier[idx]) <= 0);
923 
924 	atomic_dec(&conf->barrier[idx]);
925 	atomic_dec(&conf->nr_sync_pending);
926 	wake_up(&conf->wait_barrier);
927 }
928 
929 static bool _wait_barrier(struct r1conf *conf, int idx, bool nowait)
930 {
931 	bool ret = true;
932 
933 	/*
934 	 * We need to increase conf->nr_pending[idx] very early here,
935 	 * then raise_barrier() can be blocked when it waits for
936 	 * conf->nr_pending[idx] to be 0. Then we can avoid holding
937 	 * conf->resync_lock when there is no barrier raised in same
938 	 * barrier unit bucket. Also if the array is frozen, I/O
939 	 * should be blocked until array is unfrozen.
940 	 */
941 	atomic_inc(&conf->nr_pending[idx]);
942 	/*
943 	 * In _wait_barrier() we firstly increase conf->nr_pending[idx], then
944 	 * check conf->barrier[idx]. In raise_barrier() we firstly increase
945 	 * conf->barrier[idx], then check conf->nr_pending[idx]. A memory
946 	 * barrier is necessary here to make sure conf->barrier[idx] won't be
947 	 * fetched before conf->nr_pending[idx] is increased. Otherwise there
948 	 * will be a race between _wait_barrier() and raise_barrier().
949 	 */
950 	smp_mb__after_atomic();
951 
952 	/*
953 	 * Don't worry about checking two atomic_t variables at same time
954 	 * here. If during we check conf->barrier[idx], the array is
955 	 * frozen (conf->array_frozen is 1), and chonf->barrier[idx] is
956 	 * 0, it is safe to return and make the I/O continue. Because the
957 	 * array is frozen, all I/O returned here will eventually complete
958 	 * or be queued, no race will happen. See code comment in
959 	 * frozen_array().
960 	 */
961 	if (!READ_ONCE(conf->array_frozen) &&
962 	    !atomic_read(&conf->barrier[idx]))
963 		return ret;
964 
965 	/*
966 	 * After holding conf->resync_lock, conf->nr_pending[idx]
967 	 * should be decreased before waiting for barrier to drop.
968 	 * Otherwise, we may encounter a race condition because
969 	 * raise_barrer() might be waiting for conf->nr_pending[idx]
970 	 * to be 0 at same time.
971 	 */
972 	spin_lock_irq(&conf->resync_lock);
973 	atomic_inc(&conf->nr_waiting[idx]);
974 	atomic_dec(&conf->nr_pending[idx]);
975 	/*
976 	 * In case freeze_array() is waiting for
977 	 * get_unqueued_pending() == extra
978 	 */
979 	wake_up_barrier(conf);
980 	/* Wait for the barrier in same barrier unit bucket to drop. */
981 
982 	/* Return false when nowait flag is set */
983 	if (nowait) {
984 		ret = false;
985 	} else {
986 		wait_event_lock_irq(conf->wait_barrier,
987 				!conf->array_frozen &&
988 				!atomic_read(&conf->barrier[idx]),
989 				conf->resync_lock);
990 		atomic_inc(&conf->nr_pending[idx]);
991 	}
992 
993 	atomic_dec(&conf->nr_waiting[idx]);
994 	spin_unlock_irq(&conf->resync_lock);
995 	return ret;
996 }
997 
998 static bool wait_read_barrier(struct r1conf *conf, sector_t sector_nr, bool nowait)
999 {
1000 	int idx = sector_to_idx(sector_nr);
1001 	bool ret = true;
1002 
1003 	/*
1004 	 * Very similar to _wait_barrier(). The difference is, for read
1005 	 * I/O we don't need wait for sync I/O, but if the whole array
1006 	 * is frozen, the read I/O still has to wait until the array is
1007 	 * unfrozen. Since there is no ordering requirement with
1008 	 * conf->barrier[idx] here, memory barrier is unnecessary as well.
1009 	 */
1010 	atomic_inc(&conf->nr_pending[idx]);
1011 
1012 	if (!READ_ONCE(conf->array_frozen))
1013 		return ret;
1014 
1015 	spin_lock_irq(&conf->resync_lock);
1016 	atomic_inc(&conf->nr_waiting[idx]);
1017 	atomic_dec(&conf->nr_pending[idx]);
1018 	/*
1019 	 * In case freeze_array() is waiting for
1020 	 * get_unqueued_pending() == extra
1021 	 */
1022 	wake_up_barrier(conf);
1023 	/* Wait for array to be unfrozen */
1024 
1025 	/* Return false when nowait flag is set */
1026 	if (nowait) {
1027 		/* Return false when nowait flag is set */
1028 		ret = false;
1029 	} else {
1030 		wait_event_lock_irq(conf->wait_barrier,
1031 				!conf->array_frozen,
1032 				conf->resync_lock);
1033 		atomic_inc(&conf->nr_pending[idx]);
1034 	}
1035 
1036 	atomic_dec(&conf->nr_waiting[idx]);
1037 	spin_unlock_irq(&conf->resync_lock);
1038 	return ret;
1039 }
1040 
1041 static bool wait_barrier(struct r1conf *conf, sector_t sector_nr, bool nowait)
1042 {
1043 	int idx = sector_to_idx(sector_nr);
1044 
1045 	return _wait_barrier(conf, idx, nowait);
1046 }
1047 
1048 static void _allow_barrier(struct r1conf *conf, int idx)
1049 {
1050 	atomic_dec(&conf->nr_pending[idx]);
1051 	wake_up_barrier(conf);
1052 }
1053 
1054 static void allow_barrier(struct r1conf *conf, sector_t sector_nr)
1055 {
1056 	int idx = sector_to_idx(sector_nr);
1057 
1058 	_allow_barrier(conf, idx);
1059 }
1060 
1061 /* conf->resync_lock should be held */
1062 static int get_unqueued_pending(struct r1conf *conf)
1063 {
1064 	int idx, ret;
1065 
1066 	ret = atomic_read(&conf->nr_sync_pending);
1067 	for (idx = 0; idx < BARRIER_BUCKETS_NR; idx++)
1068 		ret += atomic_read(&conf->nr_pending[idx]) -
1069 			atomic_read(&conf->nr_queued[idx]);
1070 
1071 	return ret;
1072 }
1073 
1074 static void freeze_array(struct r1conf *conf, int extra)
1075 {
1076 	/* Stop sync I/O and normal I/O and wait for everything to
1077 	 * go quiet.
1078 	 * This is called in two situations:
1079 	 * 1) management command handlers (reshape, remove disk, quiesce).
1080 	 * 2) one normal I/O request failed.
1081 
1082 	 * After array_frozen is set to 1, new sync IO will be blocked at
1083 	 * raise_barrier(), and new normal I/O will blocked at _wait_barrier()
1084 	 * or wait_read_barrier(). The flying I/Os will either complete or be
1085 	 * queued. When everything goes quite, there are only queued I/Os left.
1086 
1087 	 * Every flying I/O contributes to a conf->nr_pending[idx], idx is the
1088 	 * barrier bucket index which this I/O request hits. When all sync and
1089 	 * normal I/O are queued, sum of all conf->nr_pending[] will match sum
1090 	 * of all conf->nr_queued[]. But normal I/O failure is an exception,
1091 	 * in handle_read_error(), we may call freeze_array() before trying to
1092 	 * fix the read error. In this case, the error read I/O is not queued,
1093 	 * so get_unqueued_pending() == 1.
1094 	 *
1095 	 * Therefore before this function returns, we need to wait until
1096 	 * get_unqueued_pendings(conf) gets equal to extra. For
1097 	 * normal I/O context, extra is 1, in rested situations extra is 0.
1098 	 */
1099 	spin_lock_irq(&conf->resync_lock);
1100 	conf->array_frozen = 1;
1101 	raid1_log(conf->mddev, "wait freeze");
1102 	wait_event_lock_irq_cmd(
1103 		conf->wait_barrier,
1104 		get_unqueued_pending(conf) == extra,
1105 		conf->resync_lock,
1106 		flush_pending_writes(conf));
1107 	spin_unlock_irq(&conf->resync_lock);
1108 }
1109 static void unfreeze_array(struct r1conf *conf)
1110 {
1111 	/* reverse the effect of the freeze */
1112 	spin_lock_irq(&conf->resync_lock);
1113 	conf->array_frozen = 0;
1114 	spin_unlock_irq(&conf->resync_lock);
1115 	wake_up(&conf->wait_barrier);
1116 }
1117 
1118 static void alloc_behind_master_bio(struct r1bio *r1_bio,
1119 					   struct bio *bio)
1120 {
1121 	int size = bio->bi_iter.bi_size;
1122 	unsigned vcnt = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
1123 	int i = 0;
1124 	struct bio *behind_bio = NULL;
1125 
1126 	behind_bio = bio_alloc_bioset(NULL, vcnt, 0, GFP_NOIO,
1127 				      &r1_bio->mddev->bio_set);
1128 
1129 	/* discard op, we don't support writezero/writesame yet */
1130 	if (!bio_has_data(bio)) {
1131 		behind_bio->bi_iter.bi_size = size;
1132 		goto skip_copy;
1133 	}
1134 
1135 	while (i < vcnt && size) {
1136 		struct page *page;
1137 		int len = min_t(int, PAGE_SIZE, size);
1138 
1139 		page = alloc_page(GFP_NOIO);
1140 		if (unlikely(!page))
1141 			goto free_pages;
1142 
1143 		if (!bio_add_page(behind_bio, page, len, 0)) {
1144 			put_page(page);
1145 			goto free_pages;
1146 		}
1147 
1148 		size -= len;
1149 		i++;
1150 	}
1151 
1152 	bio_copy_data(behind_bio, bio);
1153 skip_copy:
1154 	r1_bio->behind_master_bio = behind_bio;
1155 	set_bit(R1BIO_BehindIO, &r1_bio->state);
1156 
1157 	return;
1158 
1159 free_pages:
1160 	pr_debug("%dB behind alloc failed, doing sync I/O\n",
1161 		 bio->bi_iter.bi_size);
1162 	bio_free_pages(behind_bio);
1163 	bio_put(behind_bio);
1164 }
1165 
1166 static void raid1_unplug(struct blk_plug_cb *cb, bool from_schedule)
1167 {
1168 	struct raid1_plug_cb *plug = container_of(cb, struct raid1_plug_cb,
1169 						  cb);
1170 	struct mddev *mddev = plug->cb.data;
1171 	struct r1conf *conf = mddev->private;
1172 	struct bio *bio;
1173 
1174 	if (from_schedule) {
1175 		spin_lock_irq(&conf->device_lock);
1176 		bio_list_merge(&conf->pending_bio_list, &plug->pending);
1177 		spin_unlock_irq(&conf->device_lock);
1178 		wake_up_barrier(conf);
1179 		md_wakeup_thread(mddev->thread);
1180 		kfree(plug);
1181 		return;
1182 	}
1183 
1184 	/* we aren't scheduling, so we can do the write-out directly. */
1185 	bio = bio_list_get(&plug->pending);
1186 	flush_bio_list(conf, bio);
1187 	kfree(plug);
1188 }
1189 
1190 static void init_r1bio(struct r1bio *r1_bio, struct mddev *mddev, struct bio *bio)
1191 {
1192 	r1_bio->master_bio = bio;
1193 	r1_bio->sectors = bio_sectors(bio);
1194 	r1_bio->state = 0;
1195 	r1_bio->mddev = mddev;
1196 	r1_bio->sector = bio->bi_iter.bi_sector;
1197 }
1198 
1199 static inline struct r1bio *
1200 alloc_r1bio(struct mddev *mddev, struct bio *bio)
1201 {
1202 	struct r1conf *conf = mddev->private;
1203 	struct r1bio *r1_bio;
1204 
1205 	r1_bio = mempool_alloc(&conf->r1bio_pool, GFP_NOIO);
1206 	/* Ensure no bio records IO_BLOCKED */
1207 	memset(r1_bio->bios, 0, conf->raid_disks * sizeof(r1_bio->bios[0]));
1208 	init_r1bio(r1_bio, mddev, bio);
1209 	return r1_bio;
1210 }
1211 
1212 static void raid1_read_request(struct mddev *mddev, struct bio *bio,
1213 			       int max_read_sectors, struct r1bio *r1_bio)
1214 {
1215 	struct r1conf *conf = mddev->private;
1216 	struct raid1_info *mirror;
1217 	struct bio *read_bio;
1218 	struct bitmap *bitmap = mddev->bitmap;
1219 	const enum req_op op = bio_op(bio);
1220 	const blk_opf_t do_sync = bio->bi_opf & REQ_SYNC;
1221 	int max_sectors;
1222 	int rdisk;
1223 	bool r1bio_existed = !!r1_bio;
1224 	char b[BDEVNAME_SIZE];
1225 
1226 	/*
1227 	 * If r1_bio is set, we are blocking the raid1d thread
1228 	 * so there is a tiny risk of deadlock.  So ask for
1229 	 * emergency memory if needed.
1230 	 */
1231 	gfp_t gfp = r1_bio ? (GFP_NOIO | __GFP_HIGH) : GFP_NOIO;
1232 
1233 	if (r1bio_existed) {
1234 		/* Need to get the block device name carefully */
1235 		struct md_rdev *rdev = conf->mirrors[r1_bio->read_disk].rdev;
1236 
1237 		if (rdev)
1238 			snprintf(b, sizeof(b), "%pg", rdev->bdev);
1239 		else
1240 			strcpy(b, "???");
1241 	}
1242 
1243 	/*
1244 	 * Still need barrier for READ in case that whole
1245 	 * array is frozen.
1246 	 */
1247 	if (!wait_read_barrier(conf, bio->bi_iter.bi_sector,
1248 				bio->bi_opf & REQ_NOWAIT)) {
1249 		bio_wouldblock_error(bio);
1250 		return;
1251 	}
1252 
1253 	if (!r1_bio)
1254 		r1_bio = alloc_r1bio(mddev, bio);
1255 	else
1256 		init_r1bio(r1_bio, mddev, bio);
1257 	r1_bio->sectors = max_read_sectors;
1258 
1259 	/*
1260 	 * make_request() can abort the operation when read-ahead is being
1261 	 * used and no empty request is available.
1262 	 */
1263 	rdisk = read_balance(conf, r1_bio, &max_sectors);
1264 
1265 	if (rdisk < 0) {
1266 		/* couldn't find anywhere to read from */
1267 		if (r1bio_existed) {
1268 			pr_crit_ratelimited("md/raid1:%s: %s: unrecoverable I/O read error for block %llu\n",
1269 					    mdname(mddev),
1270 					    b,
1271 					    (unsigned long long)r1_bio->sector);
1272 		}
1273 		raid_end_bio_io(r1_bio);
1274 		return;
1275 	}
1276 	mirror = conf->mirrors + rdisk;
1277 
1278 	if (r1bio_existed)
1279 		pr_info_ratelimited("md/raid1:%s: redirecting sector %llu to other mirror: %pg\n",
1280 				    mdname(mddev),
1281 				    (unsigned long long)r1_bio->sector,
1282 				    mirror->rdev->bdev);
1283 
1284 	if (test_bit(WriteMostly, &mirror->rdev->flags) &&
1285 	    bitmap) {
1286 		/*
1287 		 * Reading from a write-mostly device must take care not to
1288 		 * over-take any writes that are 'behind'
1289 		 */
1290 		raid1_log(mddev, "wait behind writes");
1291 		wait_event(bitmap->behind_wait,
1292 			   atomic_read(&bitmap->behind_writes) == 0);
1293 	}
1294 
1295 	if (max_sectors < bio_sectors(bio)) {
1296 		struct bio *split = bio_split(bio, max_sectors,
1297 					      gfp, &conf->bio_split);
1298 		bio_chain(split, bio);
1299 		submit_bio_noacct(bio);
1300 		bio = split;
1301 		r1_bio->master_bio = bio;
1302 		r1_bio->sectors = max_sectors;
1303 	}
1304 
1305 	r1_bio->read_disk = rdisk;
1306 	if (!r1bio_existed) {
1307 		md_account_bio(mddev, &bio);
1308 		r1_bio->master_bio = bio;
1309 	}
1310 	read_bio = bio_alloc_clone(mirror->rdev->bdev, bio, gfp,
1311 				   &mddev->bio_set);
1312 
1313 	r1_bio->bios[rdisk] = read_bio;
1314 
1315 	read_bio->bi_iter.bi_sector = r1_bio->sector +
1316 		mirror->rdev->data_offset;
1317 	read_bio->bi_end_io = raid1_end_read_request;
1318 	read_bio->bi_opf = op | do_sync;
1319 	if (test_bit(FailFast, &mirror->rdev->flags) &&
1320 	    test_bit(R1BIO_FailFast, &r1_bio->state))
1321 	        read_bio->bi_opf |= MD_FAILFAST;
1322 	read_bio->bi_private = r1_bio;
1323 
1324 	if (mddev->gendisk)
1325 	        trace_block_bio_remap(read_bio, disk_devt(mddev->gendisk),
1326 				      r1_bio->sector);
1327 
1328 	submit_bio_noacct(read_bio);
1329 }
1330 
1331 static void raid1_write_request(struct mddev *mddev, struct bio *bio,
1332 				int max_write_sectors)
1333 {
1334 	struct r1conf *conf = mddev->private;
1335 	struct r1bio *r1_bio;
1336 	int i, disks;
1337 	struct bitmap *bitmap = mddev->bitmap;
1338 	unsigned long flags;
1339 	struct md_rdev *blocked_rdev;
1340 	int first_clone;
1341 	int max_sectors;
1342 	bool write_behind = false;
1343 	bool is_discard = (bio_op(bio) == REQ_OP_DISCARD);
1344 
1345 	if (mddev_is_clustered(mddev) &&
1346 	     md_cluster_ops->area_resyncing(mddev, WRITE,
1347 		     bio->bi_iter.bi_sector, bio_end_sector(bio))) {
1348 
1349 		DEFINE_WAIT(w);
1350 		if (bio->bi_opf & REQ_NOWAIT) {
1351 			bio_wouldblock_error(bio);
1352 			return;
1353 		}
1354 		for (;;) {
1355 			prepare_to_wait(&conf->wait_barrier,
1356 					&w, TASK_IDLE);
1357 			if (!md_cluster_ops->area_resyncing(mddev, WRITE,
1358 							bio->bi_iter.bi_sector,
1359 							bio_end_sector(bio)))
1360 				break;
1361 			schedule();
1362 		}
1363 		finish_wait(&conf->wait_barrier, &w);
1364 	}
1365 
1366 	/*
1367 	 * Register the new request and wait if the reconstruction
1368 	 * thread has put up a bar for new requests.
1369 	 * Continue immediately if no resync is active currently.
1370 	 */
1371 	if (!wait_barrier(conf, bio->bi_iter.bi_sector,
1372 				bio->bi_opf & REQ_NOWAIT)) {
1373 		bio_wouldblock_error(bio);
1374 		return;
1375 	}
1376 
1377  retry_write:
1378 	r1_bio = alloc_r1bio(mddev, bio);
1379 	r1_bio->sectors = max_write_sectors;
1380 
1381 	/* first select target devices under rcu_lock and
1382 	 * inc refcount on their rdev.  Record them by setting
1383 	 * bios[x] to bio
1384 	 * If there are known/acknowledged bad blocks on any device on
1385 	 * which we have seen a write error, we want to avoid writing those
1386 	 * blocks.
1387 	 * This potentially requires several writes to write around
1388 	 * the bad blocks.  Each set of writes gets it's own r1bio
1389 	 * with a set of bios attached.
1390 	 */
1391 
1392 	disks = conf->raid_disks * 2;
1393 	blocked_rdev = NULL;
1394 	max_sectors = r1_bio->sectors;
1395 	for (i = 0;  i < disks; i++) {
1396 		struct md_rdev *rdev = conf->mirrors[i].rdev;
1397 
1398 		/*
1399 		 * The write-behind io is only attempted on drives marked as
1400 		 * write-mostly, which means we could allocate write behind
1401 		 * bio later.
1402 		 */
1403 		if (!is_discard && rdev && test_bit(WriteMostly, &rdev->flags))
1404 			write_behind = true;
1405 
1406 		if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
1407 			atomic_inc(&rdev->nr_pending);
1408 			blocked_rdev = rdev;
1409 			break;
1410 		}
1411 		r1_bio->bios[i] = NULL;
1412 		if (!rdev || test_bit(Faulty, &rdev->flags)) {
1413 			if (i < conf->raid_disks)
1414 				set_bit(R1BIO_Degraded, &r1_bio->state);
1415 			continue;
1416 		}
1417 
1418 		atomic_inc(&rdev->nr_pending);
1419 		if (test_bit(WriteErrorSeen, &rdev->flags)) {
1420 			sector_t first_bad;
1421 			int bad_sectors;
1422 			int is_bad;
1423 
1424 			is_bad = is_badblock(rdev, r1_bio->sector, max_sectors,
1425 					     &first_bad, &bad_sectors);
1426 			if (is_bad < 0) {
1427 				/* mustn't write here until the bad block is
1428 				 * acknowledged*/
1429 				set_bit(BlockedBadBlocks, &rdev->flags);
1430 				blocked_rdev = rdev;
1431 				break;
1432 			}
1433 			if (is_bad && first_bad <= r1_bio->sector) {
1434 				/* Cannot write here at all */
1435 				bad_sectors -= (r1_bio->sector - first_bad);
1436 				if (bad_sectors < max_sectors)
1437 					/* mustn't write more than bad_sectors
1438 					 * to other devices yet
1439 					 */
1440 					max_sectors = bad_sectors;
1441 				rdev_dec_pending(rdev, mddev);
1442 				/* We don't set R1BIO_Degraded as that
1443 				 * only applies if the disk is
1444 				 * missing, so it might be re-added,
1445 				 * and we want to know to recover this
1446 				 * chunk.
1447 				 * In this case the device is here,
1448 				 * and the fact that this chunk is not
1449 				 * in-sync is recorded in the bad
1450 				 * block log
1451 				 */
1452 				continue;
1453 			}
1454 			if (is_bad) {
1455 				int good_sectors = first_bad - r1_bio->sector;
1456 				if (good_sectors < max_sectors)
1457 					max_sectors = good_sectors;
1458 			}
1459 		}
1460 		r1_bio->bios[i] = bio;
1461 	}
1462 
1463 	if (unlikely(blocked_rdev)) {
1464 		/* Wait for this device to become unblocked */
1465 		int j;
1466 
1467 		for (j = 0; j < i; j++)
1468 			if (r1_bio->bios[j])
1469 				rdev_dec_pending(conf->mirrors[j].rdev, mddev);
1470 		free_r1bio(r1_bio);
1471 		allow_barrier(conf, bio->bi_iter.bi_sector);
1472 
1473 		if (bio->bi_opf & REQ_NOWAIT) {
1474 			bio_wouldblock_error(bio);
1475 			return;
1476 		}
1477 		raid1_log(mddev, "wait rdev %d blocked", blocked_rdev->raid_disk);
1478 		md_wait_for_blocked_rdev(blocked_rdev, mddev);
1479 		wait_barrier(conf, bio->bi_iter.bi_sector, false);
1480 		goto retry_write;
1481 	}
1482 
1483 	/*
1484 	 * When using a bitmap, we may call alloc_behind_master_bio below.
1485 	 * alloc_behind_master_bio allocates a copy of the data payload a page
1486 	 * at a time and thus needs a new bio that can fit the whole payload
1487 	 * this bio in page sized chunks.
1488 	 */
1489 	if (write_behind && bitmap)
1490 		max_sectors = min_t(int, max_sectors,
1491 				    BIO_MAX_VECS * (PAGE_SIZE >> 9));
1492 	if (max_sectors < bio_sectors(bio)) {
1493 		struct bio *split = bio_split(bio, max_sectors,
1494 					      GFP_NOIO, &conf->bio_split);
1495 		bio_chain(split, bio);
1496 		submit_bio_noacct(bio);
1497 		bio = split;
1498 		r1_bio->master_bio = bio;
1499 		r1_bio->sectors = max_sectors;
1500 	}
1501 
1502 	md_account_bio(mddev, &bio);
1503 	r1_bio->master_bio = bio;
1504 	atomic_set(&r1_bio->remaining, 1);
1505 	atomic_set(&r1_bio->behind_remaining, 0);
1506 
1507 	first_clone = 1;
1508 
1509 	for (i = 0; i < disks; i++) {
1510 		struct bio *mbio = NULL;
1511 		struct md_rdev *rdev = conf->mirrors[i].rdev;
1512 		if (!r1_bio->bios[i])
1513 			continue;
1514 
1515 		if (first_clone) {
1516 			/* do behind I/O ?
1517 			 * Not if there are too many, or cannot
1518 			 * allocate memory, or a reader on WriteMostly
1519 			 * is waiting for behind writes to flush */
1520 			if (bitmap && write_behind &&
1521 			    (atomic_read(&bitmap->behind_writes)
1522 			     < mddev->bitmap_info.max_write_behind) &&
1523 			    !waitqueue_active(&bitmap->behind_wait)) {
1524 				alloc_behind_master_bio(r1_bio, bio);
1525 			}
1526 
1527 			md_bitmap_startwrite(bitmap, r1_bio->sector, r1_bio->sectors,
1528 					     test_bit(R1BIO_BehindIO, &r1_bio->state));
1529 			first_clone = 0;
1530 		}
1531 
1532 		if (r1_bio->behind_master_bio) {
1533 			mbio = bio_alloc_clone(rdev->bdev,
1534 					       r1_bio->behind_master_bio,
1535 					       GFP_NOIO, &mddev->bio_set);
1536 			if (test_bit(CollisionCheck, &rdev->flags))
1537 				wait_for_serialization(rdev, r1_bio);
1538 			if (test_bit(WriteMostly, &rdev->flags))
1539 				atomic_inc(&r1_bio->behind_remaining);
1540 		} else {
1541 			mbio = bio_alloc_clone(rdev->bdev, bio, GFP_NOIO,
1542 					       &mddev->bio_set);
1543 
1544 			if (mddev->serialize_policy)
1545 				wait_for_serialization(rdev, r1_bio);
1546 		}
1547 
1548 		r1_bio->bios[i] = mbio;
1549 
1550 		mbio->bi_iter.bi_sector	= (r1_bio->sector + rdev->data_offset);
1551 		mbio->bi_end_io	= raid1_end_write_request;
1552 		mbio->bi_opf = bio_op(bio) | (bio->bi_opf & (REQ_SYNC | REQ_FUA));
1553 		if (test_bit(FailFast, &rdev->flags) &&
1554 		    !test_bit(WriteMostly, &rdev->flags) &&
1555 		    conf->raid_disks - mddev->degraded > 1)
1556 			mbio->bi_opf |= MD_FAILFAST;
1557 		mbio->bi_private = r1_bio;
1558 
1559 		atomic_inc(&r1_bio->remaining);
1560 
1561 		if (mddev->gendisk)
1562 			trace_block_bio_remap(mbio, disk_devt(mddev->gendisk),
1563 					      r1_bio->sector);
1564 		/* flush_pending_writes() needs access to the rdev so...*/
1565 		mbio->bi_bdev = (void *)rdev;
1566 		if (!raid1_add_bio_to_plug(mddev, mbio, raid1_unplug, disks)) {
1567 			spin_lock_irqsave(&conf->device_lock, flags);
1568 			bio_list_add(&conf->pending_bio_list, mbio);
1569 			spin_unlock_irqrestore(&conf->device_lock, flags);
1570 			md_wakeup_thread(mddev->thread);
1571 		}
1572 	}
1573 
1574 	r1_bio_write_done(r1_bio);
1575 
1576 	/* In case raid1d snuck in to freeze_array */
1577 	wake_up_barrier(conf);
1578 }
1579 
1580 static bool raid1_make_request(struct mddev *mddev, struct bio *bio)
1581 {
1582 	sector_t sectors;
1583 
1584 	if (unlikely(bio->bi_opf & REQ_PREFLUSH)
1585 	    && md_flush_request(mddev, bio))
1586 		return true;
1587 
1588 	/*
1589 	 * There is a limit to the maximum size, but
1590 	 * the read/write handler might find a lower limit
1591 	 * due to bad blocks.  To avoid multiple splits,
1592 	 * we pass the maximum number of sectors down
1593 	 * and let the lower level perform the split.
1594 	 */
1595 	sectors = align_to_barrier_unit_end(
1596 		bio->bi_iter.bi_sector, bio_sectors(bio));
1597 
1598 	if (bio_data_dir(bio) == READ)
1599 		raid1_read_request(mddev, bio, sectors, NULL);
1600 	else {
1601 		if (!md_write_start(mddev,bio))
1602 			return false;
1603 		raid1_write_request(mddev, bio, sectors);
1604 	}
1605 	return true;
1606 }
1607 
1608 static void raid1_status(struct seq_file *seq, struct mddev *mddev)
1609 {
1610 	struct r1conf *conf = mddev->private;
1611 	int i;
1612 
1613 	lockdep_assert_held(&mddev->lock);
1614 
1615 	seq_printf(seq, " [%d/%d] [", conf->raid_disks,
1616 		   conf->raid_disks - mddev->degraded);
1617 	for (i = 0; i < conf->raid_disks; i++) {
1618 		struct md_rdev *rdev = READ_ONCE(conf->mirrors[i].rdev);
1619 
1620 		seq_printf(seq, "%s",
1621 			   rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
1622 	}
1623 	seq_printf(seq, "]");
1624 }
1625 
1626 /**
1627  * raid1_error() - RAID1 error handler.
1628  * @mddev: affected md device.
1629  * @rdev: member device to fail.
1630  *
1631  * The routine acknowledges &rdev failure and determines new @mddev state.
1632  * If it failed, then:
1633  *	- &MD_BROKEN flag is set in &mddev->flags.
1634  *	- recovery is disabled.
1635  * Otherwise, it must be degraded:
1636  *	- recovery is interrupted.
1637  *	- &mddev->degraded is bumped.
1638  *
1639  * @rdev is marked as &Faulty excluding case when array is failed and
1640  * &mddev->fail_last_dev is off.
1641  */
1642 static void raid1_error(struct mddev *mddev, struct md_rdev *rdev)
1643 {
1644 	struct r1conf *conf = mddev->private;
1645 	unsigned long flags;
1646 
1647 	spin_lock_irqsave(&conf->device_lock, flags);
1648 
1649 	if (test_bit(In_sync, &rdev->flags) &&
1650 	    (conf->raid_disks - mddev->degraded) == 1) {
1651 		set_bit(MD_BROKEN, &mddev->flags);
1652 
1653 		if (!mddev->fail_last_dev) {
1654 			conf->recovery_disabled = mddev->recovery_disabled;
1655 			spin_unlock_irqrestore(&conf->device_lock, flags);
1656 			return;
1657 		}
1658 	}
1659 	set_bit(Blocked, &rdev->flags);
1660 	if (test_and_clear_bit(In_sync, &rdev->flags))
1661 		mddev->degraded++;
1662 	set_bit(Faulty, &rdev->flags);
1663 	spin_unlock_irqrestore(&conf->device_lock, flags);
1664 	/*
1665 	 * if recovery is running, make sure it aborts.
1666 	 */
1667 	set_bit(MD_RECOVERY_INTR, &mddev->recovery);
1668 	set_mask_bits(&mddev->sb_flags, 0,
1669 		      BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_PENDING));
1670 	pr_crit("md/raid1:%s: Disk failure on %pg, disabling device.\n"
1671 		"md/raid1:%s: Operation continuing on %d devices.\n",
1672 		mdname(mddev), rdev->bdev,
1673 		mdname(mddev), conf->raid_disks - mddev->degraded);
1674 }
1675 
1676 static void print_conf(struct r1conf *conf)
1677 {
1678 	int i;
1679 
1680 	pr_debug("RAID1 conf printout:\n");
1681 	if (!conf) {
1682 		pr_debug("(!conf)\n");
1683 		return;
1684 	}
1685 	pr_debug(" --- wd:%d rd:%d\n", conf->raid_disks - conf->mddev->degraded,
1686 		 conf->raid_disks);
1687 
1688 	lockdep_assert_held(&conf->mddev->reconfig_mutex);
1689 	for (i = 0; i < conf->raid_disks; i++) {
1690 		struct md_rdev *rdev = conf->mirrors[i].rdev;
1691 		if (rdev)
1692 			pr_debug(" disk %d, wo:%d, o:%d, dev:%pg\n",
1693 				 i, !test_bit(In_sync, &rdev->flags),
1694 				 !test_bit(Faulty, &rdev->flags),
1695 				 rdev->bdev);
1696 	}
1697 }
1698 
1699 static void close_sync(struct r1conf *conf)
1700 {
1701 	int idx;
1702 
1703 	for (idx = 0; idx < BARRIER_BUCKETS_NR; idx++) {
1704 		_wait_barrier(conf, idx, false);
1705 		_allow_barrier(conf, idx);
1706 	}
1707 
1708 	mempool_exit(&conf->r1buf_pool);
1709 }
1710 
1711 static int raid1_spare_active(struct mddev *mddev)
1712 {
1713 	int i;
1714 	struct r1conf *conf = mddev->private;
1715 	int count = 0;
1716 	unsigned long flags;
1717 
1718 	/*
1719 	 * Find all failed disks within the RAID1 configuration
1720 	 * and mark them readable.
1721 	 * Called under mddev lock, so rcu protection not needed.
1722 	 * device_lock used to avoid races with raid1_end_read_request
1723 	 * which expects 'In_sync' flags and ->degraded to be consistent.
1724 	 */
1725 	spin_lock_irqsave(&conf->device_lock, flags);
1726 	for (i = 0; i < conf->raid_disks; i++) {
1727 		struct md_rdev *rdev = conf->mirrors[i].rdev;
1728 		struct md_rdev *repl = conf->mirrors[conf->raid_disks + i].rdev;
1729 		if (repl
1730 		    && !test_bit(Candidate, &repl->flags)
1731 		    && repl->recovery_offset == MaxSector
1732 		    && !test_bit(Faulty, &repl->flags)
1733 		    && !test_and_set_bit(In_sync, &repl->flags)) {
1734 			/* replacement has just become active */
1735 			if (!rdev ||
1736 			    !test_and_clear_bit(In_sync, &rdev->flags))
1737 				count++;
1738 			if (rdev) {
1739 				/* Replaced device not technically
1740 				 * faulty, but we need to be sure
1741 				 * it gets removed and never re-added
1742 				 */
1743 				set_bit(Faulty, &rdev->flags);
1744 				sysfs_notify_dirent_safe(
1745 					rdev->sysfs_state);
1746 			}
1747 		}
1748 		if (rdev
1749 		    && rdev->recovery_offset == MaxSector
1750 		    && !test_bit(Faulty, &rdev->flags)
1751 		    && !test_and_set_bit(In_sync, &rdev->flags)) {
1752 			count++;
1753 			sysfs_notify_dirent_safe(rdev->sysfs_state);
1754 		}
1755 	}
1756 	mddev->degraded -= count;
1757 	spin_unlock_irqrestore(&conf->device_lock, flags);
1758 
1759 	print_conf(conf);
1760 	return count;
1761 }
1762 
1763 static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
1764 {
1765 	struct r1conf *conf = mddev->private;
1766 	int err = -EEXIST;
1767 	int mirror = 0, repl_slot = -1;
1768 	struct raid1_info *p;
1769 	int first = 0;
1770 	int last = conf->raid_disks - 1;
1771 
1772 	if (mddev->recovery_disabled == conf->recovery_disabled)
1773 		return -EBUSY;
1774 
1775 	if (md_integrity_add_rdev(rdev, mddev))
1776 		return -ENXIO;
1777 
1778 	if (rdev->raid_disk >= 0)
1779 		first = last = rdev->raid_disk;
1780 
1781 	/*
1782 	 * find the disk ... but prefer rdev->saved_raid_disk
1783 	 * if possible.
1784 	 */
1785 	if (rdev->saved_raid_disk >= 0 &&
1786 	    rdev->saved_raid_disk >= first &&
1787 	    rdev->saved_raid_disk < conf->raid_disks &&
1788 	    conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
1789 		first = last = rdev->saved_raid_disk;
1790 
1791 	for (mirror = first; mirror <= last; mirror++) {
1792 		p = conf->mirrors + mirror;
1793 		if (!p->rdev) {
1794 			if (mddev->gendisk)
1795 				disk_stack_limits(mddev->gendisk, rdev->bdev,
1796 						  rdev->data_offset << 9);
1797 
1798 			p->head_position = 0;
1799 			rdev->raid_disk = mirror;
1800 			err = 0;
1801 			/* As all devices are equivalent, we don't need a full recovery
1802 			 * if this was recently any drive of the array
1803 			 */
1804 			if (rdev->saved_raid_disk < 0)
1805 				conf->fullsync = 1;
1806 			WRITE_ONCE(p->rdev, rdev);
1807 			break;
1808 		}
1809 		if (test_bit(WantReplacement, &p->rdev->flags) &&
1810 		    p[conf->raid_disks].rdev == NULL && repl_slot < 0)
1811 			repl_slot = mirror;
1812 	}
1813 
1814 	if (err && repl_slot >= 0) {
1815 		/* Add this device as a replacement */
1816 		p = conf->mirrors + repl_slot;
1817 		clear_bit(In_sync, &rdev->flags);
1818 		set_bit(Replacement, &rdev->flags);
1819 		rdev->raid_disk = repl_slot;
1820 		err = 0;
1821 		conf->fullsync = 1;
1822 		WRITE_ONCE(p[conf->raid_disks].rdev, rdev);
1823 	}
1824 
1825 	print_conf(conf);
1826 	return err;
1827 }
1828 
1829 static int raid1_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
1830 {
1831 	struct r1conf *conf = mddev->private;
1832 	int err = 0;
1833 	int number = rdev->raid_disk;
1834 	struct raid1_info *p = conf->mirrors + number;
1835 
1836 	if (unlikely(number >= conf->raid_disks))
1837 		goto abort;
1838 
1839 	if (rdev != p->rdev)
1840 		p = conf->mirrors + conf->raid_disks + number;
1841 
1842 	print_conf(conf);
1843 	if (rdev == p->rdev) {
1844 		if (test_bit(In_sync, &rdev->flags) ||
1845 		    atomic_read(&rdev->nr_pending)) {
1846 			err = -EBUSY;
1847 			goto abort;
1848 		}
1849 		/* Only remove non-faulty devices if recovery
1850 		 * is not possible.
1851 		 */
1852 		if (!test_bit(Faulty, &rdev->flags) &&
1853 		    mddev->recovery_disabled != conf->recovery_disabled &&
1854 		    mddev->degraded < conf->raid_disks) {
1855 			err = -EBUSY;
1856 			goto abort;
1857 		}
1858 		WRITE_ONCE(p->rdev, NULL);
1859 		if (conf->mirrors[conf->raid_disks + number].rdev) {
1860 			/* We just removed a device that is being replaced.
1861 			 * Move down the replacement.  We drain all IO before
1862 			 * doing this to avoid confusion.
1863 			 */
1864 			struct md_rdev *repl =
1865 				conf->mirrors[conf->raid_disks + number].rdev;
1866 			freeze_array(conf, 0);
1867 			if (atomic_read(&repl->nr_pending)) {
1868 				/* It means that some queued IO of retry_list
1869 				 * hold repl. Thus, we cannot set replacement
1870 				 * as NULL, avoiding rdev NULL pointer
1871 				 * dereference in sync_request_write and
1872 				 * handle_write_finished.
1873 				 */
1874 				err = -EBUSY;
1875 				unfreeze_array(conf);
1876 				goto abort;
1877 			}
1878 			clear_bit(Replacement, &repl->flags);
1879 			WRITE_ONCE(p->rdev, repl);
1880 			conf->mirrors[conf->raid_disks + number].rdev = NULL;
1881 			unfreeze_array(conf);
1882 		}
1883 
1884 		clear_bit(WantReplacement, &rdev->flags);
1885 		err = md_integrity_register(mddev);
1886 	}
1887 abort:
1888 
1889 	print_conf(conf);
1890 	return err;
1891 }
1892 
1893 static void end_sync_read(struct bio *bio)
1894 {
1895 	struct r1bio *r1_bio = get_resync_r1bio(bio);
1896 
1897 	update_head_pos(r1_bio->read_disk, r1_bio);
1898 
1899 	/*
1900 	 * we have read a block, now it needs to be re-written,
1901 	 * or re-read if the read failed.
1902 	 * We don't do much here, just schedule handling by raid1d
1903 	 */
1904 	if (!bio->bi_status)
1905 		set_bit(R1BIO_Uptodate, &r1_bio->state);
1906 
1907 	if (atomic_dec_and_test(&r1_bio->remaining))
1908 		reschedule_retry(r1_bio);
1909 }
1910 
1911 static void abort_sync_write(struct mddev *mddev, struct r1bio *r1_bio)
1912 {
1913 	sector_t sync_blocks = 0;
1914 	sector_t s = r1_bio->sector;
1915 	long sectors_to_go = r1_bio->sectors;
1916 
1917 	/* make sure these bits don't get cleared. */
1918 	do {
1919 		md_bitmap_end_sync(mddev->bitmap, s, &sync_blocks, 1);
1920 		s += sync_blocks;
1921 		sectors_to_go -= sync_blocks;
1922 	} while (sectors_to_go > 0);
1923 }
1924 
1925 static void put_sync_write_buf(struct r1bio *r1_bio, int uptodate)
1926 {
1927 	if (atomic_dec_and_test(&r1_bio->remaining)) {
1928 		struct mddev *mddev = r1_bio->mddev;
1929 		int s = r1_bio->sectors;
1930 
1931 		if (test_bit(R1BIO_MadeGood, &r1_bio->state) ||
1932 		    test_bit(R1BIO_WriteError, &r1_bio->state))
1933 			reschedule_retry(r1_bio);
1934 		else {
1935 			put_buf(r1_bio);
1936 			md_done_sync(mddev, s, uptodate);
1937 		}
1938 	}
1939 }
1940 
1941 static void end_sync_write(struct bio *bio)
1942 {
1943 	int uptodate = !bio->bi_status;
1944 	struct r1bio *r1_bio = get_resync_r1bio(bio);
1945 	struct mddev *mddev = r1_bio->mddev;
1946 	struct r1conf *conf = mddev->private;
1947 	sector_t first_bad;
1948 	int bad_sectors;
1949 	struct md_rdev *rdev = conf->mirrors[find_bio_disk(r1_bio, bio)].rdev;
1950 
1951 	if (!uptodate) {
1952 		abort_sync_write(mddev, r1_bio);
1953 		set_bit(WriteErrorSeen, &rdev->flags);
1954 		if (!test_and_set_bit(WantReplacement, &rdev->flags))
1955 			set_bit(MD_RECOVERY_NEEDED, &
1956 				mddev->recovery);
1957 		set_bit(R1BIO_WriteError, &r1_bio->state);
1958 	} else if (is_badblock(rdev, r1_bio->sector, r1_bio->sectors,
1959 			       &first_bad, &bad_sectors) &&
1960 		   !is_badblock(conf->mirrors[r1_bio->read_disk].rdev,
1961 				r1_bio->sector,
1962 				r1_bio->sectors,
1963 				&first_bad, &bad_sectors)
1964 		)
1965 		set_bit(R1BIO_MadeGood, &r1_bio->state);
1966 
1967 	put_sync_write_buf(r1_bio, uptodate);
1968 }
1969 
1970 static int r1_sync_page_io(struct md_rdev *rdev, sector_t sector,
1971 			   int sectors, struct page *page, blk_opf_t rw)
1972 {
1973 	if (sync_page_io(rdev, sector, sectors << 9, page, rw, false))
1974 		/* success */
1975 		return 1;
1976 	if (rw == REQ_OP_WRITE) {
1977 		set_bit(WriteErrorSeen, &rdev->flags);
1978 		if (!test_and_set_bit(WantReplacement,
1979 				      &rdev->flags))
1980 			set_bit(MD_RECOVERY_NEEDED, &
1981 				rdev->mddev->recovery);
1982 	}
1983 	/* need to record an error - either for the block or the device */
1984 	if (!rdev_set_badblocks(rdev, sector, sectors, 0))
1985 		md_error(rdev->mddev, rdev);
1986 	return 0;
1987 }
1988 
1989 static int fix_sync_read_error(struct r1bio *r1_bio)
1990 {
1991 	/* Try some synchronous reads of other devices to get
1992 	 * good data, much like with normal read errors.  Only
1993 	 * read into the pages we already have so we don't
1994 	 * need to re-issue the read request.
1995 	 * We don't need to freeze the array, because being in an
1996 	 * active sync request, there is no normal IO, and
1997 	 * no overlapping syncs.
1998 	 * We don't need to check is_badblock() again as we
1999 	 * made sure that anything with a bad block in range
2000 	 * will have bi_end_io clear.
2001 	 */
2002 	struct mddev *mddev = r1_bio->mddev;
2003 	struct r1conf *conf = mddev->private;
2004 	struct bio *bio = r1_bio->bios[r1_bio->read_disk];
2005 	struct page **pages = get_resync_pages(bio)->pages;
2006 	sector_t sect = r1_bio->sector;
2007 	int sectors = r1_bio->sectors;
2008 	int idx = 0;
2009 	struct md_rdev *rdev;
2010 
2011 	rdev = conf->mirrors[r1_bio->read_disk].rdev;
2012 	if (test_bit(FailFast, &rdev->flags)) {
2013 		/* Don't try recovering from here - just fail it
2014 		 * ... unless it is the last working device of course */
2015 		md_error(mddev, rdev);
2016 		if (test_bit(Faulty, &rdev->flags))
2017 			/* Don't try to read from here, but make sure
2018 			 * put_buf does it's thing
2019 			 */
2020 			bio->bi_end_io = end_sync_write;
2021 	}
2022 
2023 	while(sectors) {
2024 		int s = sectors;
2025 		int d = r1_bio->read_disk;
2026 		int success = 0;
2027 		int start;
2028 
2029 		if (s > (PAGE_SIZE>>9))
2030 			s = PAGE_SIZE >> 9;
2031 		do {
2032 			if (r1_bio->bios[d]->bi_end_io == end_sync_read) {
2033 				/* No rcu protection needed here devices
2034 				 * can only be removed when no resync is
2035 				 * active, and resync is currently active
2036 				 */
2037 				rdev = conf->mirrors[d].rdev;
2038 				if (sync_page_io(rdev, sect, s<<9,
2039 						 pages[idx],
2040 						 REQ_OP_READ, false)) {
2041 					success = 1;
2042 					break;
2043 				}
2044 			}
2045 			d++;
2046 			if (d == conf->raid_disks * 2)
2047 				d = 0;
2048 		} while (!success && d != r1_bio->read_disk);
2049 
2050 		if (!success) {
2051 			int abort = 0;
2052 			/* Cannot read from anywhere, this block is lost.
2053 			 * Record a bad block on each device.  If that doesn't
2054 			 * work just disable and interrupt the recovery.
2055 			 * Don't fail devices as that won't really help.
2056 			 */
2057 			pr_crit_ratelimited("md/raid1:%s: %pg: unrecoverable I/O read error for block %llu\n",
2058 					    mdname(mddev), bio->bi_bdev,
2059 					    (unsigned long long)r1_bio->sector);
2060 			for (d = 0; d < conf->raid_disks * 2; d++) {
2061 				rdev = conf->mirrors[d].rdev;
2062 				if (!rdev || test_bit(Faulty, &rdev->flags))
2063 					continue;
2064 				if (!rdev_set_badblocks(rdev, sect, s, 0))
2065 					abort = 1;
2066 			}
2067 			if (abort) {
2068 				conf->recovery_disabled =
2069 					mddev->recovery_disabled;
2070 				set_bit(MD_RECOVERY_INTR, &mddev->recovery);
2071 				md_done_sync(mddev, r1_bio->sectors, 0);
2072 				put_buf(r1_bio);
2073 				return 0;
2074 			}
2075 			/* Try next page */
2076 			sectors -= s;
2077 			sect += s;
2078 			idx++;
2079 			continue;
2080 		}
2081 
2082 		start = d;
2083 		/* write it back and re-read */
2084 		while (d != r1_bio->read_disk) {
2085 			if (d == 0)
2086 				d = conf->raid_disks * 2;
2087 			d--;
2088 			if (r1_bio->bios[d]->bi_end_io != end_sync_read)
2089 				continue;
2090 			rdev = conf->mirrors[d].rdev;
2091 			if (r1_sync_page_io(rdev, sect, s,
2092 					    pages[idx],
2093 					    REQ_OP_WRITE) == 0) {
2094 				r1_bio->bios[d]->bi_end_io = NULL;
2095 				rdev_dec_pending(rdev, mddev);
2096 			}
2097 		}
2098 		d = start;
2099 		while (d != r1_bio->read_disk) {
2100 			if (d == 0)
2101 				d = conf->raid_disks * 2;
2102 			d--;
2103 			if (r1_bio->bios[d]->bi_end_io != end_sync_read)
2104 				continue;
2105 			rdev = conf->mirrors[d].rdev;
2106 			if (r1_sync_page_io(rdev, sect, s,
2107 					    pages[idx],
2108 					    REQ_OP_READ) != 0)
2109 				atomic_add(s, &rdev->corrected_errors);
2110 		}
2111 		sectors -= s;
2112 		sect += s;
2113 		idx ++;
2114 	}
2115 	set_bit(R1BIO_Uptodate, &r1_bio->state);
2116 	bio->bi_status = 0;
2117 	return 1;
2118 }
2119 
2120 static void process_checks(struct r1bio *r1_bio)
2121 {
2122 	/* We have read all readable devices.  If we haven't
2123 	 * got the block, then there is no hope left.
2124 	 * If we have, then we want to do a comparison
2125 	 * and skip the write if everything is the same.
2126 	 * If any blocks failed to read, then we need to
2127 	 * attempt an over-write
2128 	 */
2129 	struct mddev *mddev = r1_bio->mddev;
2130 	struct r1conf *conf = mddev->private;
2131 	int primary;
2132 	int i;
2133 	int vcnt;
2134 
2135 	/* Fix variable parts of all bios */
2136 	vcnt = (r1_bio->sectors + PAGE_SIZE / 512 - 1) >> (PAGE_SHIFT - 9);
2137 	for (i = 0; i < conf->raid_disks * 2; i++) {
2138 		blk_status_t status;
2139 		struct bio *b = r1_bio->bios[i];
2140 		struct resync_pages *rp = get_resync_pages(b);
2141 		if (b->bi_end_io != end_sync_read)
2142 			continue;
2143 		/* fixup the bio for reuse, but preserve errno */
2144 		status = b->bi_status;
2145 		bio_reset(b, conf->mirrors[i].rdev->bdev, REQ_OP_READ);
2146 		b->bi_status = status;
2147 		b->bi_iter.bi_sector = r1_bio->sector +
2148 			conf->mirrors[i].rdev->data_offset;
2149 		b->bi_end_io = end_sync_read;
2150 		rp->raid_bio = r1_bio;
2151 		b->bi_private = rp;
2152 
2153 		/* initialize bvec table again */
2154 		md_bio_reset_resync_pages(b, rp, r1_bio->sectors << 9);
2155 	}
2156 	for (primary = 0; primary < conf->raid_disks * 2; primary++)
2157 		if (r1_bio->bios[primary]->bi_end_io == end_sync_read &&
2158 		    !r1_bio->bios[primary]->bi_status) {
2159 			r1_bio->bios[primary]->bi_end_io = NULL;
2160 			rdev_dec_pending(conf->mirrors[primary].rdev, mddev);
2161 			break;
2162 		}
2163 	r1_bio->read_disk = primary;
2164 	for (i = 0; i < conf->raid_disks * 2; i++) {
2165 		int j = 0;
2166 		struct bio *pbio = r1_bio->bios[primary];
2167 		struct bio *sbio = r1_bio->bios[i];
2168 		blk_status_t status = sbio->bi_status;
2169 		struct page **ppages = get_resync_pages(pbio)->pages;
2170 		struct page **spages = get_resync_pages(sbio)->pages;
2171 		struct bio_vec *bi;
2172 		int page_len[RESYNC_PAGES] = { 0 };
2173 		struct bvec_iter_all iter_all;
2174 
2175 		if (sbio->bi_end_io != end_sync_read)
2176 			continue;
2177 		/* Now we can 'fixup' the error value */
2178 		sbio->bi_status = 0;
2179 
2180 		bio_for_each_segment_all(bi, sbio, iter_all)
2181 			page_len[j++] = bi->bv_len;
2182 
2183 		if (!status) {
2184 			for (j = vcnt; j-- ; ) {
2185 				if (memcmp(page_address(ppages[j]),
2186 					   page_address(spages[j]),
2187 					   page_len[j]))
2188 					break;
2189 			}
2190 		} else
2191 			j = 0;
2192 		if (j >= 0)
2193 			atomic64_add(r1_bio->sectors, &mddev->resync_mismatches);
2194 		if (j < 0 || (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)
2195 			      && !status)) {
2196 			/* No need to write to this device. */
2197 			sbio->bi_end_io = NULL;
2198 			rdev_dec_pending(conf->mirrors[i].rdev, mddev);
2199 			continue;
2200 		}
2201 
2202 		bio_copy_data(sbio, pbio);
2203 	}
2204 }
2205 
2206 static void sync_request_write(struct mddev *mddev, struct r1bio *r1_bio)
2207 {
2208 	struct r1conf *conf = mddev->private;
2209 	int i;
2210 	int disks = conf->raid_disks * 2;
2211 	struct bio *wbio;
2212 
2213 	if (!test_bit(R1BIO_Uptodate, &r1_bio->state))
2214 		/* ouch - failed to read all of that. */
2215 		if (!fix_sync_read_error(r1_bio))
2216 			return;
2217 
2218 	if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
2219 		process_checks(r1_bio);
2220 
2221 	/*
2222 	 * schedule writes
2223 	 */
2224 	atomic_set(&r1_bio->remaining, 1);
2225 	for (i = 0; i < disks ; i++) {
2226 		wbio = r1_bio->bios[i];
2227 		if (wbio->bi_end_io == NULL ||
2228 		    (wbio->bi_end_io == end_sync_read &&
2229 		     (i == r1_bio->read_disk ||
2230 		      !test_bit(MD_RECOVERY_SYNC, &mddev->recovery))))
2231 			continue;
2232 		if (test_bit(Faulty, &conf->mirrors[i].rdev->flags)) {
2233 			abort_sync_write(mddev, r1_bio);
2234 			continue;
2235 		}
2236 
2237 		wbio->bi_opf = REQ_OP_WRITE;
2238 		if (test_bit(FailFast, &conf->mirrors[i].rdev->flags))
2239 			wbio->bi_opf |= MD_FAILFAST;
2240 
2241 		wbio->bi_end_io = end_sync_write;
2242 		atomic_inc(&r1_bio->remaining);
2243 		md_sync_acct(conf->mirrors[i].rdev->bdev, bio_sectors(wbio));
2244 
2245 		submit_bio_noacct(wbio);
2246 	}
2247 
2248 	put_sync_write_buf(r1_bio, 1);
2249 }
2250 
2251 /*
2252  * This is a kernel thread which:
2253  *
2254  *	1.	Retries failed read operations on working mirrors.
2255  *	2.	Updates the raid superblock when problems encounter.
2256  *	3.	Performs writes following reads for array synchronising.
2257  */
2258 
2259 static void fix_read_error(struct r1conf *conf, struct r1bio *r1_bio)
2260 {
2261 	sector_t sect = r1_bio->sector;
2262 	int sectors = r1_bio->sectors;
2263 	int read_disk = r1_bio->read_disk;
2264 	struct mddev *mddev = conf->mddev;
2265 	struct md_rdev *rdev = conf->mirrors[read_disk].rdev;
2266 
2267 	if (exceed_read_errors(mddev, rdev)) {
2268 		r1_bio->bios[r1_bio->read_disk] = IO_BLOCKED;
2269 		return;
2270 	}
2271 
2272 	while(sectors) {
2273 		int s = sectors;
2274 		int d = read_disk;
2275 		int success = 0;
2276 		int start;
2277 
2278 		if (s > (PAGE_SIZE>>9))
2279 			s = PAGE_SIZE >> 9;
2280 
2281 		do {
2282 			sector_t first_bad;
2283 			int bad_sectors;
2284 
2285 			rdev = conf->mirrors[d].rdev;
2286 			if (rdev &&
2287 			    (test_bit(In_sync, &rdev->flags) ||
2288 			     (!test_bit(Faulty, &rdev->flags) &&
2289 			      rdev->recovery_offset >= sect + s)) &&
2290 			    is_badblock(rdev, sect, s,
2291 					&first_bad, &bad_sectors) == 0) {
2292 				atomic_inc(&rdev->nr_pending);
2293 				if (sync_page_io(rdev, sect, s<<9,
2294 					 conf->tmppage, REQ_OP_READ, false))
2295 					success = 1;
2296 				rdev_dec_pending(rdev, mddev);
2297 				if (success)
2298 					break;
2299 			}
2300 
2301 			d++;
2302 			if (d == conf->raid_disks * 2)
2303 				d = 0;
2304 		} while (d != read_disk);
2305 
2306 		if (!success) {
2307 			/* Cannot read from anywhere - mark it bad */
2308 			struct md_rdev *rdev = conf->mirrors[read_disk].rdev;
2309 			if (!rdev_set_badblocks(rdev, sect, s, 0))
2310 				md_error(mddev, rdev);
2311 			break;
2312 		}
2313 		/* write it back and re-read */
2314 		start = d;
2315 		while (d != read_disk) {
2316 			if (d==0)
2317 				d = conf->raid_disks * 2;
2318 			d--;
2319 			rdev = conf->mirrors[d].rdev;
2320 			if (rdev &&
2321 			    !test_bit(Faulty, &rdev->flags)) {
2322 				atomic_inc(&rdev->nr_pending);
2323 				r1_sync_page_io(rdev, sect, s,
2324 						conf->tmppage, REQ_OP_WRITE);
2325 				rdev_dec_pending(rdev, mddev);
2326 			}
2327 		}
2328 		d = start;
2329 		while (d != read_disk) {
2330 			if (d==0)
2331 				d = conf->raid_disks * 2;
2332 			d--;
2333 			rdev = conf->mirrors[d].rdev;
2334 			if (rdev &&
2335 			    !test_bit(Faulty, &rdev->flags)) {
2336 				atomic_inc(&rdev->nr_pending);
2337 				if (r1_sync_page_io(rdev, sect, s,
2338 						conf->tmppage, REQ_OP_READ)) {
2339 					atomic_add(s, &rdev->corrected_errors);
2340 					pr_info("md/raid1:%s: read error corrected (%d sectors at %llu on %pg)\n",
2341 						mdname(mddev), s,
2342 						(unsigned long long)(sect +
2343 								     rdev->data_offset),
2344 						rdev->bdev);
2345 				}
2346 				rdev_dec_pending(rdev, mddev);
2347 			}
2348 		}
2349 		sectors -= s;
2350 		sect += s;
2351 	}
2352 }
2353 
2354 static int narrow_write_error(struct r1bio *r1_bio, int i)
2355 {
2356 	struct mddev *mddev = r1_bio->mddev;
2357 	struct r1conf *conf = mddev->private;
2358 	struct md_rdev *rdev = conf->mirrors[i].rdev;
2359 
2360 	/* bio has the data to be written to device 'i' where
2361 	 * we just recently had a write error.
2362 	 * We repeatedly clone the bio and trim down to one block,
2363 	 * then try the write.  Where the write fails we record
2364 	 * a bad block.
2365 	 * It is conceivable that the bio doesn't exactly align with
2366 	 * blocks.  We must handle this somehow.
2367 	 *
2368 	 * We currently own a reference on the rdev.
2369 	 */
2370 
2371 	int block_sectors;
2372 	sector_t sector;
2373 	int sectors;
2374 	int sect_to_write = r1_bio->sectors;
2375 	int ok = 1;
2376 
2377 	if (rdev->badblocks.shift < 0)
2378 		return 0;
2379 
2380 	block_sectors = roundup(1 << rdev->badblocks.shift,
2381 				bdev_logical_block_size(rdev->bdev) >> 9);
2382 	sector = r1_bio->sector;
2383 	sectors = ((sector + block_sectors)
2384 		   & ~(sector_t)(block_sectors - 1))
2385 		- sector;
2386 
2387 	while (sect_to_write) {
2388 		struct bio *wbio;
2389 		if (sectors > sect_to_write)
2390 			sectors = sect_to_write;
2391 		/* Write at 'sector' for 'sectors'*/
2392 
2393 		if (test_bit(R1BIO_BehindIO, &r1_bio->state)) {
2394 			wbio = bio_alloc_clone(rdev->bdev,
2395 					       r1_bio->behind_master_bio,
2396 					       GFP_NOIO, &mddev->bio_set);
2397 		} else {
2398 			wbio = bio_alloc_clone(rdev->bdev, r1_bio->master_bio,
2399 					       GFP_NOIO, &mddev->bio_set);
2400 		}
2401 
2402 		wbio->bi_opf = REQ_OP_WRITE;
2403 		wbio->bi_iter.bi_sector = r1_bio->sector;
2404 		wbio->bi_iter.bi_size = r1_bio->sectors << 9;
2405 
2406 		bio_trim(wbio, sector - r1_bio->sector, sectors);
2407 		wbio->bi_iter.bi_sector += rdev->data_offset;
2408 
2409 		if (submit_bio_wait(wbio) < 0)
2410 			/* failure! */
2411 			ok = rdev_set_badblocks(rdev, sector,
2412 						sectors, 0)
2413 				&& ok;
2414 
2415 		bio_put(wbio);
2416 		sect_to_write -= sectors;
2417 		sector += sectors;
2418 		sectors = block_sectors;
2419 	}
2420 	return ok;
2421 }
2422 
2423 static void handle_sync_write_finished(struct r1conf *conf, struct r1bio *r1_bio)
2424 {
2425 	int m;
2426 	int s = r1_bio->sectors;
2427 	for (m = 0; m < conf->raid_disks * 2 ; m++) {
2428 		struct md_rdev *rdev = conf->mirrors[m].rdev;
2429 		struct bio *bio = r1_bio->bios[m];
2430 		if (bio->bi_end_io == NULL)
2431 			continue;
2432 		if (!bio->bi_status &&
2433 		    test_bit(R1BIO_MadeGood, &r1_bio->state)) {
2434 			rdev_clear_badblocks(rdev, r1_bio->sector, s, 0);
2435 		}
2436 		if (bio->bi_status &&
2437 		    test_bit(R1BIO_WriteError, &r1_bio->state)) {
2438 			if (!rdev_set_badblocks(rdev, r1_bio->sector, s, 0))
2439 				md_error(conf->mddev, rdev);
2440 		}
2441 	}
2442 	put_buf(r1_bio);
2443 	md_done_sync(conf->mddev, s, 1);
2444 }
2445 
2446 static void handle_write_finished(struct r1conf *conf, struct r1bio *r1_bio)
2447 {
2448 	int m, idx;
2449 	bool fail = false;
2450 
2451 	for (m = 0; m < conf->raid_disks * 2 ; m++)
2452 		if (r1_bio->bios[m] == IO_MADE_GOOD) {
2453 			struct md_rdev *rdev = conf->mirrors[m].rdev;
2454 			rdev_clear_badblocks(rdev,
2455 					     r1_bio->sector,
2456 					     r1_bio->sectors, 0);
2457 			rdev_dec_pending(rdev, conf->mddev);
2458 		} else if (r1_bio->bios[m] != NULL) {
2459 			/* This drive got a write error.  We need to
2460 			 * narrow down and record precise write
2461 			 * errors.
2462 			 */
2463 			fail = true;
2464 			if (!narrow_write_error(r1_bio, m)) {
2465 				md_error(conf->mddev,
2466 					 conf->mirrors[m].rdev);
2467 				/* an I/O failed, we can't clear the bitmap */
2468 				set_bit(R1BIO_Degraded, &r1_bio->state);
2469 			}
2470 			rdev_dec_pending(conf->mirrors[m].rdev,
2471 					 conf->mddev);
2472 		}
2473 	if (fail) {
2474 		spin_lock_irq(&conf->device_lock);
2475 		list_add(&r1_bio->retry_list, &conf->bio_end_io_list);
2476 		idx = sector_to_idx(r1_bio->sector);
2477 		atomic_inc(&conf->nr_queued[idx]);
2478 		spin_unlock_irq(&conf->device_lock);
2479 		/*
2480 		 * In case freeze_array() is waiting for condition
2481 		 * get_unqueued_pending() == extra to be true.
2482 		 */
2483 		wake_up(&conf->wait_barrier);
2484 		md_wakeup_thread(conf->mddev->thread);
2485 	} else {
2486 		if (test_bit(R1BIO_WriteError, &r1_bio->state))
2487 			close_write(r1_bio);
2488 		raid_end_bio_io(r1_bio);
2489 	}
2490 }
2491 
2492 static void handle_read_error(struct r1conf *conf, struct r1bio *r1_bio)
2493 {
2494 	struct mddev *mddev = conf->mddev;
2495 	struct bio *bio;
2496 	struct md_rdev *rdev;
2497 	sector_t sector;
2498 
2499 	clear_bit(R1BIO_ReadError, &r1_bio->state);
2500 	/* we got a read error. Maybe the drive is bad.  Maybe just
2501 	 * the block and we can fix it.
2502 	 * We freeze all other IO, and try reading the block from
2503 	 * other devices.  When we find one, we re-write
2504 	 * and check it that fixes the read error.
2505 	 * This is all done synchronously while the array is
2506 	 * frozen
2507 	 */
2508 
2509 	bio = r1_bio->bios[r1_bio->read_disk];
2510 	bio_put(bio);
2511 	r1_bio->bios[r1_bio->read_disk] = NULL;
2512 
2513 	rdev = conf->mirrors[r1_bio->read_disk].rdev;
2514 	if (mddev->ro == 0
2515 	    && !test_bit(FailFast, &rdev->flags)) {
2516 		freeze_array(conf, 1);
2517 		fix_read_error(conf, r1_bio);
2518 		unfreeze_array(conf);
2519 	} else if (mddev->ro == 0 && test_bit(FailFast, &rdev->flags)) {
2520 		md_error(mddev, rdev);
2521 	} else {
2522 		r1_bio->bios[r1_bio->read_disk] = IO_BLOCKED;
2523 	}
2524 
2525 	rdev_dec_pending(rdev, conf->mddev);
2526 	sector = r1_bio->sector;
2527 	bio = r1_bio->master_bio;
2528 
2529 	/* Reuse the old r1_bio so that the IO_BLOCKED settings are preserved */
2530 	r1_bio->state = 0;
2531 	raid1_read_request(mddev, bio, r1_bio->sectors, r1_bio);
2532 	allow_barrier(conf, sector);
2533 }
2534 
2535 static void raid1d(struct md_thread *thread)
2536 {
2537 	struct mddev *mddev = thread->mddev;
2538 	struct r1bio *r1_bio;
2539 	unsigned long flags;
2540 	struct r1conf *conf = mddev->private;
2541 	struct list_head *head = &conf->retry_list;
2542 	struct blk_plug plug;
2543 	int idx;
2544 
2545 	md_check_recovery(mddev);
2546 
2547 	if (!list_empty_careful(&conf->bio_end_io_list) &&
2548 	    !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) {
2549 		LIST_HEAD(tmp);
2550 		spin_lock_irqsave(&conf->device_lock, flags);
2551 		if (!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags))
2552 			list_splice_init(&conf->bio_end_io_list, &tmp);
2553 		spin_unlock_irqrestore(&conf->device_lock, flags);
2554 		while (!list_empty(&tmp)) {
2555 			r1_bio = list_first_entry(&tmp, struct r1bio,
2556 						  retry_list);
2557 			list_del(&r1_bio->retry_list);
2558 			idx = sector_to_idx(r1_bio->sector);
2559 			atomic_dec(&conf->nr_queued[idx]);
2560 			if (mddev->degraded)
2561 				set_bit(R1BIO_Degraded, &r1_bio->state);
2562 			if (test_bit(R1BIO_WriteError, &r1_bio->state))
2563 				close_write(r1_bio);
2564 			raid_end_bio_io(r1_bio);
2565 		}
2566 	}
2567 
2568 	blk_start_plug(&plug);
2569 	for (;;) {
2570 
2571 		flush_pending_writes(conf);
2572 
2573 		spin_lock_irqsave(&conf->device_lock, flags);
2574 		if (list_empty(head)) {
2575 			spin_unlock_irqrestore(&conf->device_lock, flags);
2576 			break;
2577 		}
2578 		r1_bio = list_entry(head->prev, struct r1bio, retry_list);
2579 		list_del(head->prev);
2580 		idx = sector_to_idx(r1_bio->sector);
2581 		atomic_dec(&conf->nr_queued[idx]);
2582 		spin_unlock_irqrestore(&conf->device_lock, flags);
2583 
2584 		mddev = r1_bio->mddev;
2585 		conf = mddev->private;
2586 		if (test_bit(R1BIO_IsSync, &r1_bio->state)) {
2587 			if (test_bit(R1BIO_MadeGood, &r1_bio->state) ||
2588 			    test_bit(R1BIO_WriteError, &r1_bio->state))
2589 				handle_sync_write_finished(conf, r1_bio);
2590 			else
2591 				sync_request_write(mddev, r1_bio);
2592 		} else if (test_bit(R1BIO_MadeGood, &r1_bio->state) ||
2593 			   test_bit(R1BIO_WriteError, &r1_bio->state))
2594 			handle_write_finished(conf, r1_bio);
2595 		else if (test_bit(R1BIO_ReadError, &r1_bio->state))
2596 			handle_read_error(conf, r1_bio);
2597 		else
2598 			WARN_ON_ONCE(1);
2599 
2600 		cond_resched();
2601 		if (mddev->sb_flags & ~(1<<MD_SB_CHANGE_PENDING))
2602 			md_check_recovery(mddev);
2603 	}
2604 	blk_finish_plug(&plug);
2605 }
2606 
2607 static int init_resync(struct r1conf *conf)
2608 {
2609 	int buffs;
2610 
2611 	buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
2612 	BUG_ON(mempool_initialized(&conf->r1buf_pool));
2613 
2614 	return mempool_init(&conf->r1buf_pool, buffs, r1buf_pool_alloc,
2615 			    r1buf_pool_free, conf->poolinfo);
2616 }
2617 
2618 static struct r1bio *raid1_alloc_init_r1buf(struct r1conf *conf)
2619 {
2620 	struct r1bio *r1bio = mempool_alloc(&conf->r1buf_pool, GFP_NOIO);
2621 	struct resync_pages *rps;
2622 	struct bio *bio;
2623 	int i;
2624 
2625 	for (i = conf->poolinfo->raid_disks; i--; ) {
2626 		bio = r1bio->bios[i];
2627 		rps = bio->bi_private;
2628 		bio_reset(bio, NULL, 0);
2629 		bio->bi_private = rps;
2630 	}
2631 	r1bio->master_bio = NULL;
2632 	return r1bio;
2633 }
2634 
2635 /*
2636  * perform a "sync" on one "block"
2637  *
2638  * We need to make sure that no normal I/O request - particularly write
2639  * requests - conflict with active sync requests.
2640  *
2641  * This is achieved by tracking pending requests and a 'barrier' concept
2642  * that can be installed to exclude normal IO requests.
2643  */
2644 
2645 static sector_t raid1_sync_request(struct mddev *mddev, sector_t sector_nr,
2646 				   int *skipped)
2647 {
2648 	struct r1conf *conf = mddev->private;
2649 	struct r1bio *r1_bio;
2650 	struct bio *bio;
2651 	sector_t max_sector, nr_sectors;
2652 	int disk = -1;
2653 	int i;
2654 	int wonly = -1;
2655 	int write_targets = 0, read_targets = 0;
2656 	sector_t sync_blocks;
2657 	int still_degraded = 0;
2658 	int good_sectors = RESYNC_SECTORS;
2659 	int min_bad = 0; /* number of sectors that are bad in all devices */
2660 	int idx = sector_to_idx(sector_nr);
2661 	int page_idx = 0;
2662 
2663 	if (!mempool_initialized(&conf->r1buf_pool))
2664 		if (init_resync(conf))
2665 			return 0;
2666 
2667 	max_sector = mddev->dev_sectors;
2668 	if (sector_nr >= max_sector) {
2669 		/* If we aborted, we need to abort the
2670 		 * sync on the 'current' bitmap chunk (there will
2671 		 * only be one in raid1 resync.
2672 		 * We can find the current addess in mddev->curr_resync
2673 		 */
2674 		if (mddev->curr_resync < max_sector) /* aborted */
2675 			md_bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
2676 					   &sync_blocks, 1);
2677 		else /* completed sync */
2678 			conf->fullsync = 0;
2679 
2680 		md_bitmap_close_sync(mddev->bitmap);
2681 		close_sync(conf);
2682 
2683 		if (mddev_is_clustered(mddev)) {
2684 			conf->cluster_sync_low = 0;
2685 			conf->cluster_sync_high = 0;
2686 		}
2687 		return 0;
2688 	}
2689 
2690 	if (mddev->bitmap == NULL &&
2691 	    mddev->recovery_cp == MaxSector &&
2692 	    !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
2693 	    conf->fullsync == 0) {
2694 		*skipped = 1;
2695 		return max_sector - sector_nr;
2696 	}
2697 	/* before building a request, check if we can skip these blocks..
2698 	 * This call the bitmap_start_sync doesn't actually record anything
2699 	 */
2700 	if (!md_bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
2701 	    !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
2702 		/* We can skip this block, and probably several more */
2703 		*skipped = 1;
2704 		return sync_blocks;
2705 	}
2706 
2707 	/*
2708 	 * If there is non-resync activity waiting for a turn, then let it
2709 	 * though before starting on this new sync request.
2710 	 */
2711 	if (atomic_read(&conf->nr_waiting[idx]))
2712 		schedule_timeout_uninterruptible(1);
2713 
2714 	/* we are incrementing sector_nr below. To be safe, we check against
2715 	 * sector_nr + two times RESYNC_SECTORS
2716 	 */
2717 
2718 	md_bitmap_cond_end_sync(mddev->bitmap, sector_nr,
2719 		mddev_is_clustered(mddev) && (sector_nr + 2 * RESYNC_SECTORS > conf->cluster_sync_high));
2720 
2721 
2722 	if (raise_barrier(conf, sector_nr))
2723 		return 0;
2724 
2725 	r1_bio = raid1_alloc_init_r1buf(conf);
2726 
2727 	/*
2728 	 * If we get a correctably read error during resync or recovery,
2729 	 * we might want to read from a different device.  So we
2730 	 * flag all drives that could conceivably be read from for READ,
2731 	 * and any others (which will be non-In_sync devices) for WRITE.
2732 	 * If a read fails, we try reading from something else for which READ
2733 	 * is OK.
2734 	 */
2735 
2736 	r1_bio->mddev = mddev;
2737 	r1_bio->sector = sector_nr;
2738 	r1_bio->state = 0;
2739 	set_bit(R1BIO_IsSync, &r1_bio->state);
2740 	/* make sure good_sectors won't go across barrier unit boundary */
2741 	good_sectors = align_to_barrier_unit_end(sector_nr, good_sectors);
2742 
2743 	for (i = 0; i < conf->raid_disks * 2; i++) {
2744 		struct md_rdev *rdev;
2745 		bio = r1_bio->bios[i];
2746 
2747 		rdev = conf->mirrors[i].rdev;
2748 		if (rdev == NULL ||
2749 		    test_bit(Faulty, &rdev->flags)) {
2750 			if (i < conf->raid_disks)
2751 				still_degraded = 1;
2752 		} else if (!test_bit(In_sync, &rdev->flags)) {
2753 			bio->bi_opf = REQ_OP_WRITE;
2754 			bio->bi_end_io = end_sync_write;
2755 			write_targets ++;
2756 		} else {
2757 			/* may need to read from here */
2758 			sector_t first_bad = MaxSector;
2759 			int bad_sectors;
2760 
2761 			if (is_badblock(rdev, sector_nr, good_sectors,
2762 					&first_bad, &bad_sectors)) {
2763 				if (first_bad > sector_nr)
2764 					good_sectors = first_bad - sector_nr;
2765 				else {
2766 					bad_sectors -= (sector_nr - first_bad);
2767 					if (min_bad == 0 ||
2768 					    min_bad > bad_sectors)
2769 						min_bad = bad_sectors;
2770 				}
2771 			}
2772 			if (sector_nr < first_bad) {
2773 				if (test_bit(WriteMostly, &rdev->flags)) {
2774 					if (wonly < 0)
2775 						wonly = i;
2776 				} else {
2777 					if (disk < 0)
2778 						disk = i;
2779 				}
2780 				bio->bi_opf = REQ_OP_READ;
2781 				bio->bi_end_io = end_sync_read;
2782 				read_targets++;
2783 			} else if (!test_bit(WriteErrorSeen, &rdev->flags) &&
2784 				test_bit(MD_RECOVERY_SYNC, &mddev->recovery) &&
2785 				!test_bit(MD_RECOVERY_CHECK, &mddev->recovery)) {
2786 				/*
2787 				 * The device is suitable for reading (InSync),
2788 				 * but has bad block(s) here. Let's try to correct them,
2789 				 * if we are doing resync or repair. Otherwise, leave
2790 				 * this device alone for this sync request.
2791 				 */
2792 				bio->bi_opf = REQ_OP_WRITE;
2793 				bio->bi_end_io = end_sync_write;
2794 				write_targets++;
2795 			}
2796 		}
2797 		if (rdev && bio->bi_end_io) {
2798 			atomic_inc(&rdev->nr_pending);
2799 			bio->bi_iter.bi_sector = sector_nr + rdev->data_offset;
2800 			bio_set_dev(bio, rdev->bdev);
2801 			if (test_bit(FailFast, &rdev->flags))
2802 				bio->bi_opf |= MD_FAILFAST;
2803 		}
2804 	}
2805 	if (disk < 0)
2806 		disk = wonly;
2807 	r1_bio->read_disk = disk;
2808 
2809 	if (read_targets == 0 && min_bad > 0) {
2810 		/* These sectors are bad on all InSync devices, so we
2811 		 * need to mark them bad on all write targets
2812 		 */
2813 		int ok = 1;
2814 		for (i = 0 ; i < conf->raid_disks * 2 ; i++)
2815 			if (r1_bio->bios[i]->bi_end_io == end_sync_write) {
2816 				struct md_rdev *rdev = conf->mirrors[i].rdev;
2817 				ok = rdev_set_badblocks(rdev, sector_nr,
2818 							min_bad, 0
2819 					) && ok;
2820 			}
2821 		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
2822 		*skipped = 1;
2823 		put_buf(r1_bio);
2824 
2825 		if (!ok) {
2826 			/* Cannot record the badblocks, so need to
2827 			 * abort the resync.
2828 			 * If there are multiple read targets, could just
2829 			 * fail the really bad ones ???
2830 			 */
2831 			conf->recovery_disabled = mddev->recovery_disabled;
2832 			set_bit(MD_RECOVERY_INTR, &mddev->recovery);
2833 			return 0;
2834 		} else
2835 			return min_bad;
2836 
2837 	}
2838 	if (min_bad > 0 && min_bad < good_sectors) {
2839 		/* only resync enough to reach the next bad->good
2840 		 * transition */
2841 		good_sectors = min_bad;
2842 	}
2843 
2844 	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) && read_targets > 0)
2845 		/* extra read targets are also write targets */
2846 		write_targets += read_targets-1;
2847 
2848 	if (write_targets == 0 || read_targets == 0) {
2849 		/* There is nowhere to write, so all non-sync
2850 		 * drives must be failed - so we are finished
2851 		 */
2852 		sector_t rv;
2853 		if (min_bad > 0)
2854 			max_sector = sector_nr + min_bad;
2855 		rv = max_sector - sector_nr;
2856 		*skipped = 1;
2857 		put_buf(r1_bio);
2858 		return rv;
2859 	}
2860 
2861 	if (max_sector > mddev->resync_max)
2862 		max_sector = mddev->resync_max; /* Don't do IO beyond here */
2863 	if (max_sector > sector_nr + good_sectors)
2864 		max_sector = sector_nr + good_sectors;
2865 	nr_sectors = 0;
2866 	sync_blocks = 0;
2867 	do {
2868 		struct page *page;
2869 		int len = PAGE_SIZE;
2870 		if (sector_nr + (len>>9) > max_sector)
2871 			len = (max_sector - sector_nr) << 9;
2872 		if (len == 0)
2873 			break;
2874 		if (sync_blocks == 0) {
2875 			if (!md_bitmap_start_sync(mddev->bitmap, sector_nr,
2876 						  &sync_blocks, still_degraded) &&
2877 			    !conf->fullsync &&
2878 			    !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
2879 				break;
2880 			if ((len >> 9) > sync_blocks)
2881 				len = sync_blocks<<9;
2882 		}
2883 
2884 		for (i = 0 ; i < conf->raid_disks * 2; i++) {
2885 			struct resync_pages *rp;
2886 
2887 			bio = r1_bio->bios[i];
2888 			rp = get_resync_pages(bio);
2889 			if (bio->bi_end_io) {
2890 				page = resync_fetch_page(rp, page_idx);
2891 
2892 				/*
2893 				 * won't fail because the vec table is big
2894 				 * enough to hold all these pages
2895 				 */
2896 				__bio_add_page(bio, page, len, 0);
2897 			}
2898 		}
2899 		nr_sectors += len>>9;
2900 		sector_nr += len>>9;
2901 		sync_blocks -= (len>>9);
2902 	} while (++page_idx < RESYNC_PAGES);
2903 
2904 	r1_bio->sectors = nr_sectors;
2905 
2906 	if (mddev_is_clustered(mddev) &&
2907 			conf->cluster_sync_high < sector_nr + nr_sectors) {
2908 		conf->cluster_sync_low = mddev->curr_resync_completed;
2909 		conf->cluster_sync_high = conf->cluster_sync_low + CLUSTER_RESYNC_WINDOW_SECTORS;
2910 		/* Send resync message */
2911 		md_cluster_ops->resync_info_update(mddev,
2912 				conf->cluster_sync_low,
2913 				conf->cluster_sync_high);
2914 	}
2915 
2916 	/* For a user-requested sync, we read all readable devices and do a
2917 	 * compare
2918 	 */
2919 	if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
2920 		atomic_set(&r1_bio->remaining, read_targets);
2921 		for (i = 0; i < conf->raid_disks * 2 && read_targets; i++) {
2922 			bio = r1_bio->bios[i];
2923 			if (bio->bi_end_io == end_sync_read) {
2924 				read_targets--;
2925 				md_sync_acct_bio(bio, nr_sectors);
2926 				if (read_targets == 1)
2927 					bio->bi_opf &= ~MD_FAILFAST;
2928 				submit_bio_noacct(bio);
2929 			}
2930 		}
2931 	} else {
2932 		atomic_set(&r1_bio->remaining, 1);
2933 		bio = r1_bio->bios[r1_bio->read_disk];
2934 		md_sync_acct_bio(bio, nr_sectors);
2935 		if (read_targets == 1)
2936 			bio->bi_opf &= ~MD_FAILFAST;
2937 		submit_bio_noacct(bio);
2938 	}
2939 	return nr_sectors;
2940 }
2941 
2942 static sector_t raid1_size(struct mddev *mddev, sector_t sectors, int raid_disks)
2943 {
2944 	if (sectors)
2945 		return sectors;
2946 
2947 	return mddev->dev_sectors;
2948 }
2949 
2950 static struct r1conf *setup_conf(struct mddev *mddev)
2951 {
2952 	struct r1conf *conf;
2953 	int i;
2954 	struct raid1_info *disk;
2955 	struct md_rdev *rdev;
2956 	int err = -ENOMEM;
2957 
2958 	conf = kzalloc(sizeof(struct r1conf), GFP_KERNEL);
2959 	if (!conf)
2960 		goto abort;
2961 
2962 	conf->nr_pending = kcalloc(BARRIER_BUCKETS_NR,
2963 				   sizeof(atomic_t), GFP_KERNEL);
2964 	if (!conf->nr_pending)
2965 		goto abort;
2966 
2967 	conf->nr_waiting = kcalloc(BARRIER_BUCKETS_NR,
2968 				   sizeof(atomic_t), GFP_KERNEL);
2969 	if (!conf->nr_waiting)
2970 		goto abort;
2971 
2972 	conf->nr_queued = kcalloc(BARRIER_BUCKETS_NR,
2973 				  sizeof(atomic_t), GFP_KERNEL);
2974 	if (!conf->nr_queued)
2975 		goto abort;
2976 
2977 	conf->barrier = kcalloc(BARRIER_BUCKETS_NR,
2978 				sizeof(atomic_t), GFP_KERNEL);
2979 	if (!conf->barrier)
2980 		goto abort;
2981 
2982 	conf->mirrors = kzalloc(array3_size(sizeof(struct raid1_info),
2983 					    mddev->raid_disks, 2),
2984 				GFP_KERNEL);
2985 	if (!conf->mirrors)
2986 		goto abort;
2987 
2988 	conf->tmppage = alloc_page(GFP_KERNEL);
2989 	if (!conf->tmppage)
2990 		goto abort;
2991 
2992 	conf->poolinfo = kzalloc(sizeof(*conf->poolinfo), GFP_KERNEL);
2993 	if (!conf->poolinfo)
2994 		goto abort;
2995 	conf->poolinfo->raid_disks = mddev->raid_disks * 2;
2996 	err = mempool_init(&conf->r1bio_pool, NR_RAID_BIOS, r1bio_pool_alloc,
2997 			   rbio_pool_free, conf->poolinfo);
2998 	if (err)
2999 		goto abort;
3000 
3001 	err = bioset_init(&conf->bio_split, BIO_POOL_SIZE, 0, 0);
3002 	if (err)
3003 		goto abort;
3004 
3005 	conf->poolinfo->mddev = mddev;
3006 
3007 	err = -EINVAL;
3008 	spin_lock_init(&conf->device_lock);
3009 	rdev_for_each(rdev, mddev) {
3010 		int disk_idx = rdev->raid_disk;
3011 		if (disk_idx >= mddev->raid_disks
3012 		    || disk_idx < 0)
3013 			continue;
3014 		if (test_bit(Replacement, &rdev->flags))
3015 			disk = conf->mirrors + mddev->raid_disks + disk_idx;
3016 		else
3017 			disk = conf->mirrors + disk_idx;
3018 
3019 		if (disk->rdev)
3020 			goto abort;
3021 		disk->rdev = rdev;
3022 		disk->head_position = 0;
3023 		disk->seq_start = MaxSector;
3024 	}
3025 	conf->raid_disks = mddev->raid_disks;
3026 	conf->mddev = mddev;
3027 	INIT_LIST_HEAD(&conf->retry_list);
3028 	INIT_LIST_HEAD(&conf->bio_end_io_list);
3029 
3030 	spin_lock_init(&conf->resync_lock);
3031 	init_waitqueue_head(&conf->wait_barrier);
3032 
3033 	bio_list_init(&conf->pending_bio_list);
3034 	conf->recovery_disabled = mddev->recovery_disabled - 1;
3035 
3036 	err = -EIO;
3037 	for (i = 0; i < conf->raid_disks * 2; i++) {
3038 
3039 		disk = conf->mirrors + i;
3040 
3041 		if (i < conf->raid_disks &&
3042 		    disk[conf->raid_disks].rdev) {
3043 			/* This slot has a replacement. */
3044 			if (!disk->rdev) {
3045 				/* No original, just make the replacement
3046 				 * a recovering spare
3047 				 */
3048 				disk->rdev =
3049 					disk[conf->raid_disks].rdev;
3050 				disk[conf->raid_disks].rdev = NULL;
3051 			} else if (!test_bit(In_sync, &disk->rdev->flags))
3052 				/* Original is not in_sync - bad */
3053 				goto abort;
3054 		}
3055 
3056 		if (!disk->rdev ||
3057 		    !test_bit(In_sync, &disk->rdev->flags)) {
3058 			disk->head_position = 0;
3059 			if (disk->rdev &&
3060 			    (disk->rdev->saved_raid_disk < 0))
3061 				conf->fullsync = 1;
3062 		}
3063 	}
3064 
3065 	err = -ENOMEM;
3066 	rcu_assign_pointer(conf->thread,
3067 			   md_register_thread(raid1d, mddev, "raid1"));
3068 	if (!conf->thread)
3069 		goto abort;
3070 
3071 	return conf;
3072 
3073  abort:
3074 	if (conf) {
3075 		mempool_exit(&conf->r1bio_pool);
3076 		kfree(conf->mirrors);
3077 		safe_put_page(conf->tmppage);
3078 		kfree(conf->poolinfo);
3079 		kfree(conf->nr_pending);
3080 		kfree(conf->nr_waiting);
3081 		kfree(conf->nr_queued);
3082 		kfree(conf->barrier);
3083 		bioset_exit(&conf->bio_split);
3084 		kfree(conf);
3085 	}
3086 	return ERR_PTR(err);
3087 }
3088 
3089 static void raid1_free(struct mddev *mddev, void *priv);
3090 static int raid1_run(struct mddev *mddev)
3091 {
3092 	struct r1conf *conf;
3093 	int i;
3094 	struct md_rdev *rdev;
3095 	int ret;
3096 
3097 	if (mddev->level != 1) {
3098 		pr_warn("md/raid1:%s: raid level not set to mirroring (%d)\n",
3099 			mdname(mddev), mddev->level);
3100 		return -EIO;
3101 	}
3102 	if (mddev->reshape_position != MaxSector) {
3103 		pr_warn("md/raid1:%s: reshape_position set but not supported\n",
3104 			mdname(mddev));
3105 		return -EIO;
3106 	}
3107 
3108 	/*
3109 	 * copy the already verified devices into our private RAID1
3110 	 * bookkeeping area. [whatever we allocate in run(),
3111 	 * should be freed in raid1_free()]
3112 	 */
3113 	if (mddev->private == NULL)
3114 		conf = setup_conf(mddev);
3115 	else
3116 		conf = mddev->private;
3117 
3118 	if (IS_ERR(conf))
3119 		return PTR_ERR(conf);
3120 
3121 	if (mddev->queue)
3122 		blk_queue_max_write_zeroes_sectors(mddev->queue, 0);
3123 
3124 	rdev_for_each(rdev, mddev) {
3125 		if (!mddev->gendisk)
3126 			continue;
3127 		disk_stack_limits(mddev->gendisk, rdev->bdev,
3128 				  rdev->data_offset << 9);
3129 	}
3130 
3131 	mddev->degraded = 0;
3132 	for (i = 0; i < conf->raid_disks; i++)
3133 		if (conf->mirrors[i].rdev == NULL ||
3134 		    !test_bit(In_sync, &conf->mirrors[i].rdev->flags) ||
3135 		    test_bit(Faulty, &conf->mirrors[i].rdev->flags))
3136 			mddev->degraded++;
3137 	/*
3138 	 * RAID1 needs at least one disk in active
3139 	 */
3140 	if (conf->raid_disks - mddev->degraded < 1) {
3141 		md_unregister_thread(mddev, &conf->thread);
3142 		ret = -EINVAL;
3143 		goto abort;
3144 	}
3145 
3146 	if (conf->raid_disks - mddev->degraded == 1)
3147 		mddev->recovery_cp = MaxSector;
3148 
3149 	if (mddev->recovery_cp != MaxSector)
3150 		pr_info("md/raid1:%s: not clean -- starting background reconstruction\n",
3151 			mdname(mddev));
3152 	pr_info("md/raid1:%s: active with %d out of %d mirrors\n",
3153 		mdname(mddev), mddev->raid_disks - mddev->degraded,
3154 		mddev->raid_disks);
3155 
3156 	/*
3157 	 * Ok, everything is just fine now
3158 	 */
3159 	rcu_assign_pointer(mddev->thread, conf->thread);
3160 	rcu_assign_pointer(conf->thread, NULL);
3161 	mddev->private = conf;
3162 	set_bit(MD_FAILFAST_SUPPORTED, &mddev->flags);
3163 
3164 	md_set_array_sectors(mddev, raid1_size(mddev, 0, 0));
3165 
3166 	ret = md_integrity_register(mddev);
3167 	if (ret) {
3168 		md_unregister_thread(mddev, &mddev->thread);
3169 		goto abort;
3170 	}
3171 	return 0;
3172 
3173 abort:
3174 	raid1_free(mddev, conf);
3175 	return ret;
3176 }
3177 
3178 static void raid1_free(struct mddev *mddev, void *priv)
3179 {
3180 	struct r1conf *conf = priv;
3181 
3182 	mempool_exit(&conf->r1bio_pool);
3183 	kfree(conf->mirrors);
3184 	safe_put_page(conf->tmppage);
3185 	kfree(conf->poolinfo);
3186 	kfree(conf->nr_pending);
3187 	kfree(conf->nr_waiting);
3188 	kfree(conf->nr_queued);
3189 	kfree(conf->barrier);
3190 	bioset_exit(&conf->bio_split);
3191 	kfree(conf);
3192 }
3193 
3194 static int raid1_resize(struct mddev *mddev, sector_t sectors)
3195 {
3196 	/* no resync is happening, and there is enough space
3197 	 * on all devices, so we can resize.
3198 	 * We need to make sure resync covers any new space.
3199 	 * If the array is shrinking we should possibly wait until
3200 	 * any io in the removed space completes, but it hardly seems
3201 	 * worth it.
3202 	 */
3203 	sector_t newsize = raid1_size(mddev, sectors, 0);
3204 	if (mddev->external_size &&
3205 	    mddev->array_sectors > newsize)
3206 		return -EINVAL;
3207 	if (mddev->bitmap) {
3208 		int ret = md_bitmap_resize(mddev->bitmap, newsize, 0, 0);
3209 		if (ret)
3210 			return ret;
3211 	}
3212 	md_set_array_sectors(mddev, newsize);
3213 	if (sectors > mddev->dev_sectors &&
3214 	    mddev->recovery_cp > mddev->dev_sectors) {
3215 		mddev->recovery_cp = mddev->dev_sectors;
3216 		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
3217 	}
3218 	mddev->dev_sectors = sectors;
3219 	mddev->resync_max_sectors = sectors;
3220 	return 0;
3221 }
3222 
3223 static int raid1_reshape(struct mddev *mddev)
3224 {
3225 	/* We need to:
3226 	 * 1/ resize the r1bio_pool
3227 	 * 2/ resize conf->mirrors
3228 	 *
3229 	 * We allocate a new r1bio_pool if we can.
3230 	 * Then raise a device barrier and wait until all IO stops.
3231 	 * Then resize conf->mirrors and swap in the new r1bio pool.
3232 	 *
3233 	 * At the same time, we "pack" the devices so that all the missing
3234 	 * devices have the higher raid_disk numbers.
3235 	 */
3236 	mempool_t newpool, oldpool;
3237 	struct pool_info *newpoolinfo;
3238 	struct raid1_info *newmirrors;
3239 	struct r1conf *conf = mddev->private;
3240 	int cnt, raid_disks;
3241 	unsigned long flags;
3242 	int d, d2;
3243 	int ret;
3244 
3245 	memset(&newpool, 0, sizeof(newpool));
3246 	memset(&oldpool, 0, sizeof(oldpool));
3247 
3248 	/* Cannot change chunk_size, layout, or level */
3249 	if (mddev->chunk_sectors != mddev->new_chunk_sectors ||
3250 	    mddev->layout != mddev->new_layout ||
3251 	    mddev->level != mddev->new_level) {
3252 		mddev->new_chunk_sectors = mddev->chunk_sectors;
3253 		mddev->new_layout = mddev->layout;
3254 		mddev->new_level = mddev->level;
3255 		return -EINVAL;
3256 	}
3257 
3258 	if (!mddev_is_clustered(mddev))
3259 		md_allow_write(mddev);
3260 
3261 	raid_disks = mddev->raid_disks + mddev->delta_disks;
3262 
3263 	if (raid_disks < conf->raid_disks) {
3264 		cnt=0;
3265 		for (d= 0; d < conf->raid_disks; d++)
3266 			if (conf->mirrors[d].rdev)
3267 				cnt++;
3268 		if (cnt > raid_disks)
3269 			return -EBUSY;
3270 	}
3271 
3272 	newpoolinfo = kmalloc(sizeof(*newpoolinfo), GFP_KERNEL);
3273 	if (!newpoolinfo)
3274 		return -ENOMEM;
3275 	newpoolinfo->mddev = mddev;
3276 	newpoolinfo->raid_disks = raid_disks * 2;
3277 
3278 	ret = mempool_init(&newpool, NR_RAID_BIOS, r1bio_pool_alloc,
3279 			   rbio_pool_free, newpoolinfo);
3280 	if (ret) {
3281 		kfree(newpoolinfo);
3282 		return ret;
3283 	}
3284 	newmirrors = kzalloc(array3_size(sizeof(struct raid1_info),
3285 					 raid_disks, 2),
3286 			     GFP_KERNEL);
3287 	if (!newmirrors) {
3288 		kfree(newpoolinfo);
3289 		mempool_exit(&newpool);
3290 		return -ENOMEM;
3291 	}
3292 
3293 	freeze_array(conf, 0);
3294 
3295 	/* ok, everything is stopped */
3296 	oldpool = conf->r1bio_pool;
3297 	conf->r1bio_pool = newpool;
3298 
3299 	for (d = d2 = 0; d < conf->raid_disks; d++) {
3300 		struct md_rdev *rdev = conf->mirrors[d].rdev;
3301 		if (rdev && rdev->raid_disk != d2) {
3302 			sysfs_unlink_rdev(mddev, rdev);
3303 			rdev->raid_disk = d2;
3304 			sysfs_unlink_rdev(mddev, rdev);
3305 			if (sysfs_link_rdev(mddev, rdev))
3306 				pr_warn("md/raid1:%s: cannot register rd%d\n",
3307 					mdname(mddev), rdev->raid_disk);
3308 		}
3309 		if (rdev)
3310 			newmirrors[d2++].rdev = rdev;
3311 	}
3312 	kfree(conf->mirrors);
3313 	conf->mirrors = newmirrors;
3314 	kfree(conf->poolinfo);
3315 	conf->poolinfo = newpoolinfo;
3316 
3317 	spin_lock_irqsave(&conf->device_lock, flags);
3318 	mddev->degraded += (raid_disks - conf->raid_disks);
3319 	spin_unlock_irqrestore(&conf->device_lock, flags);
3320 	conf->raid_disks = mddev->raid_disks = raid_disks;
3321 	mddev->delta_disks = 0;
3322 
3323 	unfreeze_array(conf);
3324 
3325 	set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
3326 	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
3327 	md_wakeup_thread(mddev->thread);
3328 
3329 	mempool_exit(&oldpool);
3330 	return 0;
3331 }
3332 
3333 static void raid1_quiesce(struct mddev *mddev, int quiesce)
3334 {
3335 	struct r1conf *conf = mddev->private;
3336 
3337 	if (quiesce)
3338 		freeze_array(conf, 0);
3339 	else
3340 		unfreeze_array(conf);
3341 }
3342 
3343 static void *raid1_takeover(struct mddev *mddev)
3344 {
3345 	/* raid1 can take over:
3346 	 *  raid5 with 2 devices, any layout or chunk size
3347 	 */
3348 	if (mddev->level == 5 && mddev->raid_disks == 2) {
3349 		struct r1conf *conf;
3350 		mddev->new_level = 1;
3351 		mddev->new_layout = 0;
3352 		mddev->new_chunk_sectors = 0;
3353 		conf = setup_conf(mddev);
3354 		if (!IS_ERR(conf)) {
3355 			/* Array must appear to be quiesced */
3356 			conf->array_frozen = 1;
3357 			mddev_clear_unsupported_flags(mddev,
3358 				UNSUPPORTED_MDDEV_FLAGS);
3359 		}
3360 		return conf;
3361 	}
3362 	return ERR_PTR(-EINVAL);
3363 }
3364 
3365 static struct md_personality raid1_personality =
3366 {
3367 	.name		= "raid1",
3368 	.level		= 1,
3369 	.owner		= THIS_MODULE,
3370 	.make_request	= raid1_make_request,
3371 	.run		= raid1_run,
3372 	.free		= raid1_free,
3373 	.status		= raid1_status,
3374 	.error_handler	= raid1_error,
3375 	.hot_add_disk	= raid1_add_disk,
3376 	.hot_remove_disk= raid1_remove_disk,
3377 	.spare_active	= raid1_spare_active,
3378 	.sync_request	= raid1_sync_request,
3379 	.resize		= raid1_resize,
3380 	.size		= raid1_size,
3381 	.check_reshape	= raid1_reshape,
3382 	.quiesce	= raid1_quiesce,
3383 	.takeover	= raid1_takeover,
3384 };
3385 
3386 static int __init raid_init(void)
3387 {
3388 	return register_md_personality(&raid1_personality);
3389 }
3390 
3391 static void raid_exit(void)
3392 {
3393 	unregister_md_personality(&raid1_personality);
3394 }
3395 
3396 module_init(raid_init);
3397 module_exit(raid_exit);
3398 MODULE_LICENSE("GPL");
3399 MODULE_DESCRIPTION("RAID1 (mirroring) personality for MD");
3400 MODULE_ALIAS("md-personality-3"); /* RAID1 */
3401 MODULE_ALIAS("md-raid1");
3402 MODULE_ALIAS("md-level-1");
3403