| blob | 75771b2077c00f28950169956f9ac4baf21cbe4d |
1 /*
2 * raid1.c : Multiple Devices driver for Linux
3 *
4 * Copyright (C) 1999, 2000, 2001 Ingo Molnar, Red Hat
5 *
6 * Copyright (C) 1996, 1997, 1998 Ingo Molnar, Miguel de Icaza, Gadi Oxman
7 *
8 * RAID-1 management functions.
9 *
10 * Better read-balancing code written by Mika Kuoppala <miku@iki.fi>, 2000
11 *
12 * Fixes to reconstruction by Jakob Østergaard" <jakob@ostenfeld.dk>
13 * Various fixes by Neil Brown <neilb@cse.unsw.edu.au>
14 *
15 * Changes by Peter T. Breuer <ptb@it.uc3m.es> 31/1/2003 to support
16 * bitmapped intelligence in resync:
17 *
18 * - bitmap marked during normal i/o
19 * - bitmap used to skip nondirty blocks during sync
20 *
21 * Additions to bitmap code, (C) 2003-2004 Paul Clements, SteelEye Technology:
22 * - persistent bitmap code
23 *
24 * This program is free software; you can redistribute it and/or modify
25 * it under the terms of the GNU General Public License as published by
26 * the Free Software Foundation; either version 2, or (at your option)
27 * any later version.
28 *
29 * You should have received a copy of the GNU General Public License
30 * (for example /usr/src/linux/COPYING); if not, write to the Free
31 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
32 */
34 #include <linux/slab.h>
35 #include <linux/delay.h>
36 #include <linux/blkdev.h>
37 #include <linux/module.h>
38 #include <linux/seq_file.h>
39 #include <linux/ratelimit.h>
44 /*
45 * Number of guaranteed r1bios in case of extreme VM load:
46 */
47 #define NR_RAID1_BIOS 256
49 /* when we get a read error on a read-only array, we redirect to another
50 * device without failing the first device, or trying to over-write to
51 * correct the read error. To keep track of bad blocks on a per-bio
52 * level, we store IO_BLOCKED in the appropriate 'bios' pointer
53 */
54 #define IO_BLOCKED ((struct bio *)1)
55 /* When we successfully write to a known bad-block, we need to remove the
56 * bad-block marking which must be done from process context. So we record
57 * the success by setting devs[n].bio to IO_MADE_GOOD
58 */
59 #define IO_MADE_GOOD ((struct bio *)2)
61 #define BIO_SPECIAL(bio) ((unsigned long)bio <= 2)
63 /* When there are this many requests queue to be written by
64 * the raid1 thread, we become 'congested' to provide back-pressure
65 * for writeback.
66 */
73 {
77 /* allocate a r1bio with room for raid_disks entries in the bios array */
79 }
82 {
84 }
86 #define RESYNC_BLOCK_SIZE (64*1024)
87 //#define RESYNC_BLOCK_SIZE PAGE_SIZE
88 #define RESYNC_SECTORS (RESYNC_BLOCK_SIZE >> 9)
89 #define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
90 #define RESYNC_WINDOW (2048*1024)
93 {
104 /*
105 * Allocate bios : 1 for reading, n-1 for writing
106 */
112 }
113 /*
114 * Allocate RESYNC_PAGES data pages and attach them to
115 * the first bio.
116 * If this is a user-requested check/repair, allocate
117 * RESYNC_PAGES for each bio.
118 */
121 else
129 }
130 /* If not user-requests, copy the page pointers to all bios */
136 }
142 out_free_pages:
148 }
150 out_free_bio:
155 }
158 {
169 }
174 }
177 {
185 }
186 }
189 {
194 }
197 {
205 }
210 }
213 {
225 }
227 /*
228 * raid_end_bio_io() is called when we have finished servicing a mirrored
229 * operation and are ready to return a success/failure code to the buffer
230 * cache layer.
231 */
233 {
251 /*
252 * Wake up any possible resync thread that waits for the device
253 * to go idle.
254 */
256 }
257 }
260 {
263 /* if nobody has done the final endio yet, do it now */
272 }
274 }
276 /*
277 * Update disk head position estimator based on IRQ completion info.
278 */
280 {
285 }
287 /*
288 * Find the disk number which triggered given bio
289 */
291 {
304 }
307 {
314 /*
315 * this branch is our 'one mirror IO has finished' event handler:
316 */
322 /* If all other devices have failed, we want to return
323 * the error upwards rather than fail the last device.
324 * Here we redefine "uptodate" to mean "Don't want to retry"
325 */
333 }
339 /*
340 * oops, read error:
341 */
344 KERN_ERR "md/raid1:%s: %s: "
348 b),
352 /* don't drop the reference on read_disk yet */
353 }
354 }
357 {
358 /* it really is the end of this request */
360 /* free extra copy of the data pages */
366 }
367 /* clear the bitmap if all writes complete successfully */
373 }
376 {
386 else
388 }
389 }
392 {
401 /*
402 * 'one mirror IO has finished' event handler:
403 */
414 /*
415 * Set R1BIO_Uptodate in our master bio, so that we
416 * will return a good error code for to the higher
417 * levels even if IO on some other mirrored buffer
418 * fails.
419 *
420 * The 'master' represents the composite IO operation
421 * to user-side. So if something waits for IO, then it
422 * will wait for the 'master' bio.
423 */
424 sector_t first_bad;
429 /*
430 * Do not set R1BIO_Uptodate if the current device is
431 * rebuilding or Faulty. This is because we cannot use
432 * such device for properly reading the data back (we could
433 * potentially use it, if the current write would have felt
434 * before rdev->recovery_offset, but for simplicity we don't
435 * check this here.
436 */
441 /* Maybe we can clear some bad blocks. */
447 }
448 }
454 /*
455 * In behind mode, we ACK the master bio once the I/O
456 * has safely reached all non-writemostly
457 * disks. Setting the Returned bit ensures that this
458 * gets done only once -- we don't ever want to return
459 * -EIO here, instead we'll wait
460 */
463 /* Maybe we can return now */
472 }
473 }
474 }
479 /*
480 * Let's see if all mirrored write operations have finished
481 * already.
482 */
487 }
490 /*
491 * This routine returns the disk from which the requested read should
492 * be done. There is a per-array 'next expected sequential IO' sector
493 * number - if this matches on the next IO then we use the last disk.
494 * There is also a per-disk 'last know head position' sector that is
495 * maintained from IRQ contexts, both the normal and the resync IO
496 * completion handlers update this position correctly. If there is no
497 * perfect sequential match then we pick the disk whose head is closest.
498 *
499 * If there are 2 mirrors in the same 2 devices, performance degrades
500 * because position is mirror, not device based.
501 *
502 * The rdev for the device selected will have nr_pending incremented.
503 */
505 {
512 sector_t best_dist;
519 /*
520 * Check if we can balance. We can balance on the whole
521 * device if no resync is going on, or below the resync window.
522 * We take the first readable disk when above the resync window.
523 */
524 retry:
538 else
542 sector_t dist;
543 sector_t first_bad;
558 /* Don't balance among write-mostly, just
559 * use the first as a last resort */
564 /* Cannot use this */
570 }
572 }
573 /* This is a reasonable device to use. It might
574 * even be best.
575 */
579 /* already have a better device */
582 /* cannot read here. If this is the 'primary'
583 * device, then we must not read beyond
584 * bad_sectors from another device..
585 */
597 }
600 }
612 }
613 /* Don't change to another disk for sequential reads */
620 /*
621 * If buffered sequential IO size exceeds optimal
622 * iosize, check if there is idle disk. If yes, choose
623 * the idle disk. read_balance could already choose an
624 * idle disk before noticing it's a sequential IO in
625 * this disk. This doesn't matter because this disk
626 * will idle, next time it will be utilized after the
627 * first disk has IO size exceeds optimal iosize. In
628 * this way, iosize of the first disk will be optimal
629 * iosize at least. iosize of the second disk might be
630 * small, but not a big deal since when the second disk
631 * starts IO, the first disk is likely still busy.
632 */
640 }
642 }
643 /* If device is idle, use it */
647 }
655 }
660 }
661 }
663 /*
664 * If all disks are rotational, choose the closest disk. If any disk is
665 * non-rotational, choose the disk with less pending request even the
666 * disk is rotational, which might/might not be optimal for raids with
667 * mixed ratation/non-rotational disks depending on workload.
668 */
672 else
674 }
682 /* cannot risk returning a device that failed
683 * before we inc'ed nr_pending
684 */
687 }
694 }
699 }
704 {
725 }
726 }
727 }
729 }
732 }
735 {
751 /* Note the '|| 1' - when read_balance prefers
752 * non-congested targets, it can be removed
753 */
756 else
758 }
759 }
762 }
766 {
771 }
774 {
775 /* Any writes that have been queued but are awaiting
776 * bitmap updates get flushed here.
777 */
785 /* flush any pending bitmap writes to
786 * disk before proceeding w/ I/O */
795 /* Just ignore it */
797 else
800 }
803 }
805 /* Barriers....
806 * Sometimes we need to suspend IO while we do something else,
807 * either some resync/recovery, or reconfigure the array.
808 * To do this we raise a 'barrier'.
809 * The 'barrier' is a counter that can be raised multiple times
810 * to count how many activities are happening which preclude
811 * normal IO.
812 * We can only raise the barrier if there is no pending IO.
813 * i.e. if nr_pending == 0.
814 * We choose only to raise the barrier if no-one is waiting for the
815 * barrier to go down. This means that as soon as an IO request
816 * is ready, no other operations which require a barrier will start
817 * until the IO request has had a chance.
818 *
819 * So: regular IO calls 'wait_barrier'. When that returns there
820 * is no backgroup IO happening, It must arrange to call
821 * allow_barrier when it has finished its IO.
822 * backgroup IO calls must call raise_barrier. Once that returns
823 * there is no normal IO happeing. It must arrange to call
824 * lower_barrier when the particular background IO completes.
825 */
826 #define RESYNC_DEPTH 32
829 {
832 /* Wait until no block IO is waiting */
836 /* block any new IO from starting */
839 /* Now wait for all pending IO to complete */
845 }
848 {
855 }
858 {
862 /* Wait for the barrier to drop.
863 * However if there are already pending
864 * requests (preventing the barrier from
865 * rising completely), and the
866 * pre-process bio queue isn't empty,
867 * then don't wait, as we need to empty
868 * that queue to get the nr_pending
869 * count down.
870 */
878 }
881 }
884 {
890 }
893 {
894 /* stop syncio and normal IO and wait for everything to
895 * go quite.
896 * We increment barrier and nr_waiting, and then
897 * wait until nr_pending match nr_queued+extra
898 * This is called in the context of one normal IO request
899 * that has failed. Thus any sync request that might be pending
900 * will be blocked by nr_pending, and we need to wait for
901 * pending IO requests to complete or be queued for re-try.
902 * Thus the number queued (nr_queued) plus this request (extra)
903 * must match the number of pending IOs (nr_pending) before
904 * we continue.
905 */
914 }
916 {
917 /* reverse the effect of the freeze */
923 }
926 /* duplicate the data pages for behind I/O
927 */
929 {
933 GFP_NOIO);
946 }
952 do_sync_io:
958 }
964 };
967 {
969 cb);
983 }
985 /* we aren't scheduling, so we can do the write-out directly. */
995 /* Just ignore it */
997 else
1000 }
1002 }
1005 {
1026 /*
1027 * Register the new request and wait if the reconstruction
1028 * thread has put up a bar for new requests.
1029 * Continue immediately if no resync is active currently.
1030 */
1037 /* As the suspend_* range is controlled by
1038 * userspace, we want an interruptible
1039 * wait.
1040 */
1050 }
1052 }
1058 /*
1059 * make_request() can abort the operation when READA is being
1060 * used and no empty request is available.
1061 *
1062 */
1071 /* We might need to issue multiple reads to different
1072 * devices if there are bad blocks around, so we keep
1073 * track of the number of reads in bio->bi_phys_segments.
1074 * If this is 0, there is only one r1_bio and no locking
1075 * will be needed when requests complete. If it is
1076 * non-zero, then it is the number of not-completed requests.
1077 */
1082 /*
1083 * read balancing logic:
1084 */
1087 read_again:
1091 /* couldn't find anywhere to read from */
1094 }
1098 bitmap) {
1099 /* Reading from a write-mostly device must
1100 * take care not to over-take any writes
1101 * that are 'behind'
1102 */
1105 }
1110 max_sectors);
1121 /* could not read all from this device, so we will
1122 * need another r1_bio.
1123 */
1131 else
1134 /* Cannot call generic_make_request directly
1135 * as that will be queued in __make_request
1136 * and subsequent mempool_alloc might block waiting
1137 * for it. So hand bio over to raid1d.
1138 */
1152 }
1154 /*
1155 * WRITE:
1156 */
1161 }
1162 /* first select target devices under rcu_lock and
1163 * inc refcount on their rdev. Record them by setting
1164 * bios[x] to bio
1165 * If there are known/acknowledged bad blocks on any device on
1166 * which we have seen a write error, we want to avoid writing those
1167 * blocks.
1168 * This potentially requires several writes to write around
1169 * the bad blocks. Each set of writes gets it's own r1bio
1170 * with a set of bios attached.
1171 */
1174 retry_write:
1184 }
1191 }
1195 sector_t first_bad;
1200 max_sectors,
1203 /* mustn't write here until the bad block is
1204 * acknowledged*/
1208 }
1210 /* Cannot write here at all */
1213 /* mustn't write more than bad_sectors
1214 * to other devices yet
1215 */
1218 /* We don't set R1BIO_Degraded as that
1219 * only applies if the disk is
1220 * missing, so it might be re-added,
1221 * and we want to know to recover this
1222 * chunk.
1223 * In this case the device is here,
1224 * and the fact that this chunk is not
1225 * in-sync is recorded in the bad
1226 * block log
1227 */
1229 }
1234 }
1235 }
1237 }
1241 /* Wait for this device to become unblocked */
1252 }
1255 /* We are splitting this write into multiple parts, so
1256 * we need to prepare for allocating another r1_bio.
1257 */
1262 else
1265 }
1281 /* do behind I/O ?
1282 * Not if there are too many, or cannot
1283 * allocate memory, or a reader on WriteMostly
1284 * is waiting for behind writes to flush */
1296 }
1301 /*
1302 * We trimmed the bio, so _all is legit
1303 */
1308 }
1325 else
1334 }
1338 }
1339 /* Mustn't call r1_bio_write_done before this next test,
1340 * as it could result in the bio being freed.
1341 */
1344 /* We need another r1_bio. It has already been counted
1345 * in bio->bi_phys_segments
1346 */
1354 }
1358 /* In case raid1d snuck in to freeze_array */
1360 }
1363 {
1374 }
1377 }
1381 {
1385 /*
1386 * If it is not operational, then we have already marked it as dead
1387 * else if it is the last working disks, ignore the error, let the
1388 * next level up know.
1389 * else mark the drive as failed
1390 */
1393 /*
1394 * Don't fail the drive, act as though we were just a
1395 * normal single drive.
1396 * However don't try a recovery from this drive as
1397 * it is very likely to fail.
1398 */
1401 }
1409 /*
1410 * if recovery is running, make sure it aborts.
1411 */
1421 }
1424 {
1431 }
1444 }
1446 }
1449 {
1455 }
1458 {
1464 /*
1465 * Find all failed disks within the RAID1 configuration
1466 * and mark them readable.
1467 * Called under mddev lock, so rcu protection not needed.
1468 */
1476 /* replacement has just become active */
1479 count++;
1481 /* Replaced device not technically
1482 * faulty, but we need to be sure
1483 * it gets removed and never re-added
1484 */
1488 }
1489 }
1494 count++;
1496 }
1497 }
1504 }
1508 {
1526 }
1538 /* As all devices are equivalent, we don't need a full recovery
1539 * if this was recently any drive of the array
1540 */
1545 }
1548 /* Add this device as a replacement */
1556 }
1557 }
1559 /* Some requests might not have seen this new
1560 * merge_bvec_fn. We must wait for them to complete
1561 * before merging the device fully.
1562 * First we make sure any code which has tested
1563 * our function has submitted the request, then
1564 * we wait for all outstanding requests to complete.
1565 */
1570 }
1576 }
1579 {
1594 }
1595 /* Only remove non-faulty devices if recovery
1596 * is not possible.
1597 */
1603 }
1607 /* lost the race, try later */
1612 /* We just removed a device that is being replaced.
1613 * Move down the replacement. We drain all IO before
1614 * doing this to avoid confusion.
1615 */
1627 }
1628 abort:
1632 }
1636 {
1641 /*
1642 * we have read a block, now it needs to be re-written,
1643 * or re-read if the read failed.
1644 * We don't do much here, just schedule handling by raid1d
1645 */
1651 }
1654 {
1660 sector_t first_bad;
1669 /* make sure these bits doesn't get cleared. */
1691 )
1702 }
1703 }
1704 }
1708 {
1710 /* success */
1718 }
1719 /* need to record an error - either for the block or the device */
1723 }
1726 {
1727 /* Try some synchronous reads of other devices to get
1728 * good data, much like with normal read errors. Only
1729 * read into the pages we already have so we don't
1730 * need to re-issue the read request.
1731 * We don't need to freeze the array, because being in an
1732 * active sync request, there is no normal IO, and
1733 * no overlapping syncs.
1734 * We don't need to check is_badblock() again as we
1735 * made sure that anything with a bad block in range
1736 * will have bi_end_io clear.
1737 */
1756 /* No rcu protection needed here devices
1757 * can only be removed when no resync is
1758 * active, and resync is currently active
1759 */
1766 }
1767 }
1768 d++;
1776 /* Cannot read from anywhere, this block is lost.
1777 * Record a bad block on each device. If that doesn't
1778 * work just disable and interrupt the recovery.
1779 * Don't fail devices as that won't really help.
1780 */
1792 }
1800 }
1801 /* Try next page */
1804 idx++;
1806 }
1809 /* write it back and re-read */
1813 d--;
1822 }
1823 }
1828 d--;
1836 }
1839 idx ++;
1840 }
1844 }
1847 {
1848 /* We have read all readable devices. If we haven't
1849 * got the block, then there is no hope left.
1850 * If we have, then we want to do a comparison
1851 * and skip the write if everything is the same.
1852 * If any blocks failed to read, then we need to
1853 * attempt an over-write
1854 */
1861 /* Fix variable parts of all bios */
1870 /* fixup the bio for reuse, but preserve BIO_UPTODATE */
1890 else
1893 }
1894 }
1901 }
1911 /* Now we can 'fixup' the BIO_UPTODATE flag */
1923 }
1930 /* No need to write to this device. */
1934 }
1937 }
1939 }
1942 {
1951 /* ouch - failed to read all of that. */
1958 /*
1959 * schedule writes
1960 */
1976 }
1979 /* if we're here, all write(s) have completed, so clean up */
1987 }
1988 }
1989 }
1991 /*
1992 * This is a kernel thread which:
1993 *
1994 * 1. Retries failed read operations on working mirrors.
1995 * 2. Updates the raid superblock when problems encounter.
1996 * 3. Performs writes following reads for array synchronising.
1997 */
2001 {
2014 /* Note: no rcu protection needed here
2015 * as this is synchronous in the raid1d thread
2016 * which is the thread that might remove
2017 * a device. If raid1d ever becomes multi-threaded....
2018 */
2019 sector_t first_bad;
2033 d++;
2036 }
2040 /* Cannot read from anywhere - mark it bad */
2045 }
2046 /* write it back and re-read */
2051 d--;
2057 }
2063 d--;
2071 "md/raid1:%s: read error corrected "
2077 }
2078 }
2079 }
2082 }
2083 }
2086 {
2091 /* bio has the data to be written to device 'i' where
2092 * we just recently had a write error.
2093 * We repeatedly clone the bio and trim down to one block,
2094 * then try the write. Where the write fails we record
2095 * a bad block.
2096 * It is conceivable that the bio doesn't exactly align with
2097 * blocks. We must handle this somehow.
2098 *
2099 * We currently own a reference on the rdev.
2100 */
2103 sector_t sector;
2121 /* Write at 'sector' for 'sectors'*/
2128 vec++;
2129 vcnt--;
2130 }
2138 }
2148 /* failure! */
2157 }
2159 }
2162 {
2173 }
2178 }
2179 }
2182 }
2185 {
2195 /* This drive got a write error. We need to
2196 * narrow down and record precise write
2197 * errors.
2198 */
2202 /* an I/O failed, we can't clear the bitmap */
2204 }
2207 }
2211 }
2214 {
2223 /* we got a read error. Maybe the drive is bad. Maybe just
2224 * the block and we can fix it.
2225 * We freeze all other IO, and try reading the block from
2226 * other devices. When we find one, we re-write
2227 * and check it that fixes the read error.
2228 * This is all done synchronously while the array is
2229 * frozen
2230 */
2242 read_more:
2250 const unsigned long do_sync
2256 }
2263 "md/raid1:%s: redirecting sector %llu"
2274 /* Drat - have to split this up more */
2282 else
2300 }
2301 }
2304 {
2323 }
2335 else
2342 else
2343 /* just a partial read to be scheduled from separate
2344 * context
2345 */
2351 }
2353 }
2357 {
2368 }
2370 /*
2371 * perform a "sync" on one "block"
2372 *
2373 * We need to make sure that no normal I/O request - particularly write
2374 * requests - conflict with active sync requests.
2375 *
2376 * This is achieved by tracking pending requests and a 'barrier' concept
2377 * that can be installed to exclude normal IO requests.
2378 */
2380 static sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipped, int go_faster)
2381 {
2390 sector_t sync_blocks;
2401 /* If we aborted, we need to abort the
2402 * sync on the 'current' bitmap chunk (there will
2403 * only be one in raid1 resync.
2404 * We can find the current addess in mddev->curr_resync
2405 */
2415 }
2423 }
2424 /* before building a request, check if we can skip these blocks..
2425 * This call the bitmap_start_sync doesn't actually record anything
2426 */
2429 /* We can skip this block, and probably several more */
2432 }
2433 /*
2434 * If there is non-resync activity waiting for a turn,
2435 * and resync is going fast enough,
2436 * then let it though before starting on this new sync request.
2437 */
2448 /*
2449 * If we get a correctably read error during resync or recovery,
2450 * we might want to read from a different device. So we
2451 * flag all drives that could conceivably be read from for READ,
2452 * and any others (which will be non-In_sync devices) for WRITE.
2453 * If a read fails, we try reading from something else for which READ
2454 * is OK.
2455 */
2475 write_targets ++;
2477 /* may need to read from here */
2490 }
2491 }
2499 }
2502 read_targets++;
2506 /*
2507 * The device is suitable for reading (InSync),
2508 * but has bad block(s) here. Let's try to correct them,
2509 * if we are doing resync or repair. Otherwise, leave
2510 * this device alone for this sync request.
2511 */
2514 write_targets++;
2515 }
2516 }
2522 }
2523 }
2530 /* These sectors are bad on all InSync devices, so we
2531 * need to mark them bad on all write targets
2532 */
2540 }
2546 /* Cannot record the badblocks, so need to
2547 * abort the resync.
2548 * If there are multiple read targets, could just
2549 * fail the really bad ones ???
2550 */
2557 }
2559 /* only resync enough to reach the next bad->good
2560 * transition */
2562 }
2565 /* extra read targets are also write targets */
2569 /* There is nowhere to write, so all non-sync
2570 * drives must be failed - so we are finished
2571 */
2572 sector_t rv;
2579 }
2603 }
2610 /* stop here */
2613 i--;
2617 /* remove last page from this bio */
2621 }
2623 }
2624 }
2625 }
2630 bio_full:
2633 /* For a user-requested sync, we read all readable devices and do a
2634 * compare
2635 */
2641 read_targets--;
2644 }
2645 }
2652 }
2654 }
2657 {
2662 }
2665 {
2678 GFP_KERNEL);
2691 r1bio_pool_free,
2708 else
2720 }
2739 /* This slot has a replacement. */
2741 /* No original, just make the replacement
2742 * a recovering spare
2743 */
2748 /* Original is not in_sync - bad */
2750 }
2758 }
2759 }
2768 }
2772 abort:
2780 }
2782 }
2786 {
2797 }
2802 }
2803 /*
2804 * copy the already verified devices into our private RAID1
2805 * bookkeeping area. [whatever we allocate in run(),
2806 * should be freed in stop()]
2807 */
2810 else
2826 }
2847 /*
2848 * Ok, everything is just fine now
2849 */
2864 else
2867 }
2873 }
2876 {
2880 /* wait for behind writes to complete */
2884 /* need to kick something here to make sure I/O goes? */
2887 }
2901 }
2904 {
2905 /* no resync is happening, and there is enough space
2906 * on all devices, so we can resize.
2907 * We need to make sure resync covers any new space.
2908 * If the array is shrinking we should possibly wait until
2909 * any io in the removed space completes, but it hardly seems
2910 * worth it.
2911 */
2920 }
2928 }
2932 }
2935 {
2936 /* We need to:
2937 * 1/ resize the r1bio_pool
2938 * 2/ resize conf->mirrors
2939 *
2940 * We allocate a new r1bio_pool if we can.
2941 * Then raise a device barrier and wait until all IO stops.
2942 * Then resize conf->mirrors and swap in the new r1bio pool.
2943 *
2944 * At the same time, we "pack" the devices so that all the missing
2945 * devices have the higher raid_disk numbers.
2946 */
2955 /* Cannot change chunk_size, layout, or level */
2963 }
2975 cnt++;
2978 }
2991 }
2993 GFP_KERNEL);
2998 }
3002 /* ok, everything is stopped */
3016 }
3019 }
3038 }
3041 {
3054 }
3055 }
3058 {
3059 /* raid1 can take over:
3060 * raid5 with 2 devices, any layout or chunk size
3061 */
3071 }
3073 }
3076 {
3094 };
3097 {
3099 }
3102 {
3104 }