md/raid1: Allocate spare to store replacement devices and their bios.

In RAID1, a replacement is much like a normal device, so we just
double the size of the relevant arrays and look at all possible
devices for reads and writes.

This means that the array looks like it is now double the size in some
way - we need to be careful about that.
In particular, we checking if the array is still degraded while
creating a recovery request we need to only consider the first 'half'
- i.e. the real (non-replacement) devices.

Signed-off-by: NeilBrown <neilb@suse.de>

2 files changed, 40 insertions, 31 deletions

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index ab8113cff7c9..e7768e37f36a 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -135,7 +135,7 @@ out_free_pages:
                         put_page(r1_bio->bios[j]->bi_io_vec[i].bv_page);
         j = -1;
 out_free_bio:
-        while ( ++j < pi->raid_disks )
+        while (++j < pi->raid_disks)
                 bio_put(r1_bio->bios[j]);
         r1bio_pool_free(r1_bio, data);
         return NULL;
@@ -164,7 +164,7 @@ static void put_all_bios(struct r1conf *conf, struct r1bio *r1_bio)
 {
         int i;
 
-        for (i = 0; i < conf->raid_disks; i++) {
+        for (i = 0; i < conf->raid_disks * 2; i++) {
                 struct bio **bio = r1_bio->bios + i;
                 if (!BIO_SPECIAL(*bio))
                         bio_put(*bio);
@@ -185,7 +185,7 @@ static void put_buf(struct r1bio *r1_bio)
         struct r1conf *conf = r1_bio->mddev->private;
         int i;
 
-        for (i=0; i<conf->raid_disks; i++) {
+        for (i = 0; i < conf->raid_disks * 2; i++) {
                 struct bio *bio = r1_bio->bios[i];
                 if (bio->bi_end_io)
                         rdev_dec_pending(conf->mirrors[i].rdev, r1_bio->mddev);
@@ -280,11 +280,11 @@ static int find_bio_disk(struct r1bio *r1_bio, struct bio *bio)
         struct r1conf *conf = r1_bio->mddev->private;
         int raid_disks = conf->raid_disks;
 
-        for (mirror = 0; mirror < raid_disks; mirror++)
+        for (mirror = 0; mirror < raid_disks * 2; mirror++)
                 if (r1_bio->bios[mirror] == bio)
                         break;
 
-        BUG_ON(mirror == raid_disks);
+        BUG_ON(mirror == raid_disks * 2);
         update_head_pos(mirror, r1_bio);
 
         return mirror;
@@ -506,7 +506,7 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect
                 start_disk = conf->last_used;
         }
 
-        for (i = 0 ; i < conf->raid_disks ; i++) {
+        for (i = 0 ; i < conf->raid_disks * 2 ; i++) {
                 sector_t dist;
                 sector_t first_bad;
                 int bad_sectors;
@@ -975,7 +975,7 @@ read_again:
          */
         plugged = mddev_check_plugged(mddev);
 
-        disks = conf->raid_disks;
+        disks = conf->raid_disks * 2;
  retry_write:
         blocked_rdev = NULL;
         rcu_read_lock();
@@ -989,7 +989,8 @@ read_again:
                 }
                 r1_bio->bios[i] = NULL;
                 if (!rdev || test_bit(Faulty, &rdev->flags)) {
-                        set_bit(R1BIO_Degraded, &r1_bio->state);
+                        if (i < conf->raid_disks)
+                                set_bit(R1BIO_Degraded, &r1_bio->state);
                         continue;
                 }
 
@@ -1493,7 +1494,7 @@ static int fix_sync_read_error(struct r1bio *r1_bio)
                                 }
                         }
                         d++;
-                        if (d == conf->raid_disks)
+                        if (d == conf->raid_disks * 2)
                                 d = 0;
                 } while (!success && d != r1_bio->read_disk);
 
@@ -1510,7 +1511,7 @@ static int fix_sync_read_error(struct r1bio *r1_bio)
                                mdname(mddev),
                                bdevname(bio->bi_bdev, b),
                                (unsigned long long)r1_bio->sector);
-                        for (d = 0; d < conf->raid_disks; d++) {
+                        for (d = 0; d < conf->raid_disks * 2; d++) {
                                 rdev = conf->mirrors[d].rdev;
                                 if (!rdev || test_bit(Faulty, &rdev->flags))
                                         continue;
@@ -1536,7 +1537,7 @@ static int fix_sync_read_error(struct r1bio *r1_bio)
                 /* write it back and re-read */
                 while (d != r1_bio->read_disk) {
                         if (d == 0)
-                                d = conf->raid_disks;
+                                d = conf->raid_disks * 2;
                         d--;
                         if (r1_bio->bios[d]->bi_end_io != end_sync_read)
                                 continue;
@@ -1551,7 +1552,7 @@ static int fix_sync_read_error(struct r1bio *r1_bio)
                 d = start;
                 while (d != r1_bio->read_disk) {
                         if (d == 0)
-                                d = conf->raid_disks;
+                                d = conf->raid_disks * 2;
                         d--;
                         if (r1_bio->bios[d]->bi_end_io != end_sync_read)
                                 continue;
@@ -1584,7 +1585,7 @@ static int process_checks(struct r1bio *r1_bio)
         int primary;
         int i;
 
-        for (primary = 0; primary < conf->raid_disks; primary++)
+        for (primary = 0; primary < conf->raid_disks * 2; primary++)
                 if (r1_bio->bios[primary]->bi_end_io == end_sync_read &&
                     test_bit(BIO_UPTODATE, &r1_bio->bios[primary]->bi_flags)) {
                         r1_bio->bios[primary]->bi_end_io = NULL;
@@ -1592,7 +1593,7 @@ static int process_checks(struct r1bio *r1_bio)
                         break;
                 }
         r1_bio->read_disk = primary;
-        for (i = 0; i < conf->raid_disks; i++) {
+        for (i = 0; i < conf->raid_disks * 2; i++) {
                 int j;
                 int vcnt = r1_bio->sectors >> (PAGE_SHIFT- 9);
                 struct bio *pbio = r1_bio->bios[primary];
@@ -1656,7 +1657,7 @@ static void sync_request_write(struct mddev *mddev, struct r1bio *r1_bio)
 {
         struct r1conf *conf = mddev->private;
         int i;
-        int disks = conf->raid_disks;
+        int disks = conf->raid_disks * 2;
         struct bio *bio, *wbio;
 
         bio = r1_bio->bios[r1_bio->read_disk];
@@ -1737,7 +1738,7 @@ static void fix_read_error(struct r1conf *conf, int read_disk,
                                 success = 1;
                         else {
                                 d++;
-                                if (d == conf->raid_disks)
+                                if (d == conf->raid_disks * 2)
                                         d = 0;
                         }
                 } while (!success && d != read_disk);
@@ -1753,7 +1754,7 @@ static void fix_read_error(struct r1conf *conf, int read_disk,
                 start = d;
                 while (d != read_disk) {
                         if (d==0)
-                                d = conf->raid_disks;
+                                d = conf->raid_disks * 2;
                         d--;
                         rdev = conf->mirrors[d].rdev;
                         if (rdev &&
@@ -1765,7 +1766,7 @@ static void fix_read_error(struct r1conf *conf, int read_disk,
                 while (d != read_disk) {